BOOK I.

PARASITES OF MAN.

Whatever notions people may entertain respecting the dignity of the human race, there is no gainsaying the fact that we share with the lower animals the rather humiliating privilege and prerogative of entertaining a great variety of parasites. These are for the most part entozoal in habit. As the parasites are apt to cause suffering to the bearer, a superstitious age sought to interpret their presence as having some connection with human wrong-doing. We can now afford to smile at such erroneous ideas. The intimate relation subsisting between parasitic forms dwelling in man and animals, and their interdependence upon one another, alone suffices to preclude the idea that parasites have been arbitrarily placed within the human bearer. It would seem, indeed, that our existence is essential to the welfare and propagation of certain species of parasites. Possibly it is only by accepting the hypothesis of “Natural Selection” that we can escape the somewhat undignified conclusion that the entozoa were expressly created to dwell in us, and also that we were in part designed and destined to entertain them. View the matter as we may, the internal parasites of man and animals strictly conform to a few well-known types of structure, but these types branch out into infinitely varied specific forms. The vulgar mind sees nothing attractive in the morphology and organisation of a parasitic worm, and common-place conceptions of the beautiful cannot be expected to embrace within their narrow grasp the marvelous harmony and order that pervade the structure and economy of the individual members of this remarkable class of beings.

SECTION I.--TREMATODA (Flukes).

_Fasciola hepatica_, Linneus.--The first form I have to consider is the common liver fluke. The part this entozoon plays in the production of disease will be fully stated when treating of the parasites of the sheep and other ruminants. About twenty instances of its occurrence in the human body have been recorded. It has been found beneath the skin in the sole of the foot (Giesker), and also under the scalp (Harris), and behind the ear (Fox). Its more frequent seat is in the liver and gall-ducts (Pallas, Brera, Bidloo, Malpighi) and gall-bladder (Partridge). The alleged cases by Bauhin, Wepfer, and Chabert are spurious, as is probably also that given by Mehlis. Duval’s case appears to be genuine, but the occurrence of the worm in the portal vein was accidental. Dr Murchison has recorded a case, occurring at St Thomas’s Hospital, where a solitary specimen was found in the liver. Dr H. V. Carter also met with the worm in a young Hindoo.

In the second half of the present work I shall reproduce Blanchard’s admirable figure of the sexually mature worm (Fig. 61), accompanied by a categorical statement respecting the known facts of development. In this place, however, I may observe that the cases recorded by Giesker, Harris, and Fox had clearly pointed to the circumstance that the higher larvæ of this fluke must be armed cercariæ, otherwise they could not have bored their way through the human skin. As we shall see, Dr Willemoes-Suhm’s investigations have furnished evidence as to the truth of this supposition. For anatomical details I refer to my introductory treatise. In the adult state the liver fluke has been known from the earliest times. We have clear evidences that it was described by Gabucinus in the year 1547, and also subsequently by Cornelius Gemma, who, in a work published some thirty years later, refers to an epizootic disease prevalent in Holland during the year 1552, and which was very justly attributed to the parasite in question. After this date many writers described the liver fluke more or less accurately, and entire volumes were devoted to the consideration of the formidable disease which it occasions. The nomenclature of the parasite has been a subject of controversy. Amongst naturalists in general the common liver fluke is often described under the combined generic and specific name of _Distoma hepaticum_; but the title is both incorrect and inappropriate. The proper generic appellation of this parasite is _Fasciola_, as first proposed by the illustrious Linneus (1767) and subsequently adopted by F. Müller (1787), Brera (1811), Ramdohr (1814), and others. Unfortunately Retzius (1786) and Zeder (1800) changed the generic title without good cause, and the majority of writers, following their authority, refused to employ the original name, although a consideration of the distinctive types of structure severally displayed by the genera _Distoma_ and _Fasciola_ fairly demanded the retention of the Linnean title. In later times M. Blanchard (1847) strongly advocated the original nomenclature, and I have myself continually urged its adoption. On somewhat different grounds Professor Moquin-Tandon followed the same course.

In the sexually mature state the liver fluke commonly measures three fourths of an inch in length, occasionally reaching an entire inch or even sixteen lines; its greatest breadth also varying from half an inch to seven or eight lines transversely; body very flat, presenting distinct dorsal and ventral surfaces, frequently curled toward the latter during life; upper or anterior end suddenly constricted, produced and pointed in the centre, forming the so-called head and neck; posterior extremity less acuminated, sometimes rounded, or even slightly truncated; margins smooth, occasionally a little undulated, especially towards the upper part; oral sucker terminal, oval, rather smaller than the ventral acetabulum, which is placed immediately below the root of the neck; reproductive orifices in the middle line, a little below the oral sucker; intromittent organ usually protruded and spirally curved; a central, light-coloured space, covering two thirds of the body from above downwards, marks the region of the internal male reproductive organs, being bordered on either side and below by a continuous dark band, indicating the position of the so-called yolk-forming organs; a small, brown-coloured, rosette-like body situated directly below the ventral acetabulum, marks the limits of the uterine duct; a series of dark lines, branching downwards and outwards on either side, indicate the position of the digestive organs; general color of the body pale brownish yellow, with a slight rose tint. The surface of the body, though smooth to the naked eye, is clothed throughout with small epidermal spines which diminish in size towards the tail.

If any argument were necessary to show how desirable it is to furnish full descriptions of the commoner kinds of parasite, I could adduce numerous instances that have been brought under my notice where professional men and others have been entirely mistaken as to the essential nature of their parasitic finds. Thus, I have known an instance where a great authority on the diseases of dogs has persisted in asserting for the free proglottides of a tapeworm a nematode origin; and, in like manner, human tapeworm-segments have frequently been mistaken for independent fluke parasites. One of the most remarkable instances of this kind is that which I have elsewhere described as an error on the part of Dr Chabert. My reasons for so regarding his interpretation of the facts observed by him stand as follows:

In the ‘Boston Medical and Surgical Journal’ for the years 1852-53-54, Dr J. X. Chabert described several cases of Tænia, and he averred that the tapeworms were associated with numerous specimens of _Distoma hepaticum_. The passage of distomes by patients during life was even regarded by Dr Chabert as indicative of the presence of Tænia within the intestines. Surely, I remarked, Dr Chabert was mistaken. Are not these so-called distomes the well-known _proglottides_? Not willingly doubting Dr Chabert’s statements, but desirous, if possible, of verifying the accuracy of his conclusions, I wrote to him (March 22nd, 1864) requesting the loan of a specimen, but I was not fortunate enough to receive a reply. In the “Case of Tænia” in a boy four and a half years old, given in the 49th vol. of the journal, Dr Chabert writes as follows:--“In consequence of his passing the _Distoma hepaticum_, I concluded he must be afflicted with Tænia.” Further on it is added, that the administration of an astringent injection “caused the discharge of innumerable small worms (_Distoma hepaticum_).” I think this is quite decisive. The idea of “innumerable” flukes being expelled in this way is altogether out of the question.

The only genuine case in which any considerable number of Distomata, of this species, have been observed in the human subject is the one recently recorded by Dr Prunac. In this instance two flukes were vomited along with blood immediately after the administration of salines (sel de Seignette), and about thirty were passed per anum. On the following day, some tapeworm proglottides having been evacuated, both salts and male-fern extract were administered. This caused the expulsion of an entire tapeworm, and also about twenty more flukes. Notwithstanding this successful treatment the hæmatemesis returned in about a month, when, finally, three more flukes were vomited and the bleeding ceased. Had not the parasites been submitted for identification to a competent observer (Prof. Martins, of Montpellier), some doubt might have been entertained as to the genuineness of this remarkable case. In reference to Dr Prunac’s comments on the facts of fluke-parasitism in man, I will only remark that Dr Kerr’s Chinese cases, to which he refers, were probably due to _Distoma crassum_ and not to _D. hepaticum_. The Chinese flukes will be noticed below.

BIBLIOGRAPHY (No. 3).--Full references to details of the cases by Partridge, Fox, and Harris are given in Appendix B. to Lankester’s Edit. of _Küchenmeister’s_ Manual. See also the works of Davaine and _Leuckart_ (_l. c._ Bibl. No. 1).--_Carter, H. V._, “Note on _Distoma hepaticum_” (from a patient under the care of Mr Pandoorung), ‘Bombay Med. and Physical Soc. Trans.’ (Appendix), 1862.--_Chabert, J. X._ (quoted above). Murchison, C., ‘Clinical Lectures on Diseases of the Liver,’ (2nd Edit., Appendix), London, 1877.--_Prunac_, De la Douve ou Distome hépatique chez l’homme; in ‘Gazette des Hôpitaux’ for December, 1878 (p. 1147). For further references in this work, see Bibliog. No. 49.

_Distoma lanceolatum_, Mehlis.--At least three instances of the occurrence of this small fluke in the human body have been observed. The authority for these cases rests, severally, with Bucholz, who found them in the gall bladder in considerable numbers at Weimar; with Chabert, who expelled a large number from the intestines of a girl in France; and with Küchner, who obtained forty-seven specimens from a girl in Bohemia. Probably many similar instances have been overlooked, and Küchenmeister hints that Duval’s parasites (above mentioned) may have been this species. Although this worm will again be incidentally noticed in connection with bovine parasites (and its ciliated larvæ will also be referred to when discussing the characters of the embryo of Bilharzia), I here subjoin a diagnosis of the characters of the adult parasite. The lancet-shaped liver fluke is a small flat helminth, measuring rather more than the third of an inch in length, and about one line and a half in breadth, being also especially characterised by its lanceolate form; the widest part of the body corresponds with a transverse line drawn across the spot where the vitellaria terminate below, and from this point, on either side, the width of the animal becomes gradually narrowed towards the extremities; both ends are pointed, but the inferior or caudal one more obtusely than the anterior or oral end; the general surface is smooth throughout, and unarmed; the reproductive orifices are placed in the central line immediately in front of the ventral sucker, and below the point at which the intestine bifurcates; the oral sucker is nearly terminal, and 1/50″ in breadth, the ventral acetabulum being about the same diameter; the testes form two lobed organs placed one in front of the other in the middle line of the body and directly below the ventral sucker; the uterine canal is remarkably long, forming a series of tolerably regular folds, which occupy the central and hinder parts of the body, reaching almost to the caudal extremity. The vitelligene glands cover a limited space, on either side of the centre of the body near the margin. The _foramen caudale_ communicates with a contractile vesicle, which passes upwards in the form of a central trunk-vessel, early dividing into two main branches; these latter reach as far forwards as the œsophageal bulb, opposite which organ they suddenly curve upon themselves, retracing their course for a considerable distance backwards; the digestive canals are slightly widened towards their lower ends, which occupy a line nearly corresponding with the commencement of the lower fifth of the body; the ova are conspicuous within the uterine folds, which present a dark brownish color in front, passing to a pale yellow color below.

In reference to Kichner’s remarkable case I reproduce an abstract of it from Leuckart’s account (‘Die menschlichen Parasiten,’ Bd. i, s. 608), the original particulars of which were communicated to Leuckart by Dr Kichner himself:--

“Dr Kichner’s patient was a young girl, the daughter of the parish shepherd at Kaplitz, having been accustomed to look after the sheep ever since she was nine years old. The pasture where the animals fed was enclosed by woods, being traversed by two water dykes, and being, moreover, also supplied by ten little stagnant pools. These reservoirs harboured numerous amphibia and mollusks (such as _Lymnæus_ and _Paludina_), and the child often quenched her thirst from the half putrid water. Probably she also partook of the watercresses growing in the ditches. At length her abdomen became much distended, the limbs much emaciated, and her strength declined. Half a year before death she was confined to her bed, being all the while shamefully maltreated by her step-mother. Dr Kichner only saw her three days before her death, and ascertained that she had complained of pain (for several years) over the region of the liver. A _sectio cadaveris_ was ordered by the Government, when (in addition to the external evidences of the cruel violence to which the poor creature had been subjected) it was found that she had an enormously enlarged liver, weighing eleven pounds. The gall-bladder which was very much contracted and nearly empty, contained eight calculi and forty-seven specimens of the _Distoma lanceolatum_, all of which were sexually mature.”

As I have remarked in a former comment on this singular case, one can have no difficulty in arriving at the conclusion that these parasites were obtained from the girl’s swallowing trematode larvæ, either in their free or in their encysted condition. Leuckart says it was not possible to ascertain whether the parasites had any connection with the gall-stones, or whether the two maladies, so to speak, were independent of each other; yet this question might possibly have been solved if the calculi had been broken up in order to ascertain their structure. It is just possible that dead distomes may have formed their nuclei, and if so, the circumstance would, of course, point to the worms as the original source of the malady.

So far as I am aware, the actual transformations undergone by the larvæ of _Distoma lanceolatum_ have not been observed. The _Planorbis marginatus_ has been confidently referred to as the intermediate bearer of the cercariæ of the common fluke, and Leuckart supposes that the same mollusk harbours the larvæ of this species. The ciliated embryos carry a boring spine or tooth, and it is most probable that the higher larvæ are similarly armed.

BIBLIOGRAPHY (No. 4).--_Kichner_ (see _Leuckart_), quoted above.--_Cobbold_, ‘Entozoa’ (p. 187).--The case by Bucholz (reported as one of _Fasciola hepatica_) is given by _Jördens_ in his work (quoted by Diesing and Leuckart) ‘Entomologie und Helminthologie des menschlichen Körpers,’ (s. 64, tab. vii, fig. 14), 1802.--_Chabert’s_ French case is quoted by _Rudolphi_ in his ‘Entozoorum sive vermium,’ &c. (_loc. cit._, Bibl. No. 1), p. 326, 1808.

_Distoma crassum_, Busk.--This large species was originally discovered by Prof. Busk in the duodenum of a Lascar who died at the Seamen’s Hospital, 1843. It, however, remained undescribed until 1859, when, with the discoverer’s approval, I gave some account of it to the Linnean Society.

Of the fourteen original specimens found by Mr Busk, several have been lost. The one that he himself gave me I handed over to Prof. Leuckart, and it is figured in his work (‘Die mensch. Par.,’ s. 586). A second is preserved in the museum attached to the Middlesex Hospital, and a third is contained in the Museum of the Royal College of Surgeons. This last-named specimen is the best of the original set. It supplied me with the few details of structure figured in outline in my ‘Introductory Treatise’ (fig. 42, p. 123), published in 1864; and it also in part formed the basis of the description of the species communicated to the Linnean Society in June, 1859 (“Synopsis of the Distomidæ,” p. 5, ‘Proceedings,’ vol. v). The late Dr Lankester, it is true, was the first to give a distinctive title to this entozoon (_Distoma Buskii_); but as the discoverer objected to this nomenclature, and as Dr Lankester’s proposed terms were unaccompanied by any original description, I requested Mr Busk to suggest a new name for the worm, which he accordingly did. As I subsequently pointed out, Von Siebold had already employed the compound title _Distoma crassum_ to designate a small fluke infesting the house-martin (_Hirundo urbica_); but for reasons similar to those which contributed to set aside Dr Lankester’s nomenclature, the title adopted in my synopsis at length came to be recognised by Leuckart and by other well-known helminthologists. Before this recognition took place, Dr Weinland, of Frankfort, had so far accepted Lankester’s nomenclature as to call the species _Dicrocœlium Buskii_. In my judgment there are no sufficient grounds for retaining Dujardin’s genus. Further, I may observe that, in addition to the above-mentioned specimens, two others are preserved in the Museum at King’s College. Thus, only five out of the fourteen specimens are still in existence.

No well-authenticated second instance of the occurrence of this worm took place until the year 1873, when a missionary and his wife from China consulted Dr George Johnson respecting parasites from which they were suffering. After a brief interval, both of Dr Johnson’s patients were by an act of courtesy on the part of this eminent physician placed under my professional care. I need hardly add that Dr Johnson had from the very first recognised the trematode character of the parasites. From the patients themselves I ascertained that they had been resident in China for about four years. During that period they had together freely partaken of fresh vegetables in the form of salad, and also occasionally of oysters, but more particularly of fish, which, in common with the oysters, abound in the neighbourhood of Ningpo. From their statements it appeared to me that to one or other of these sources we must look for an explanation of the fact of their concurrent infection. Fluke larvæ, as we know, abound in mollusks and fish; but whether any of the forms hitherto found in oysters or in fish have any genetic relation to the flukes of man, is a question that cannot very well be settled in the absence of direct experimental proof. I should add that it was not until after their visit to the interior of the country, some 130 miles distant from Ningpo, that the symptoms (which Dr Johnson in the first instance, and myself subsequently, considered to have been due to the presence of the parasites) made their appearance. Whilst in the country the missionary and his wife freely partook of freshwater fish, and on one occasion they received a quantity of oysters that had been sent up from Ningpo. The husband assured me that the fish were always thoroughly well cooked.

If it be asked what were the symptoms produced, I can only furnish such few and hitherto unpublished particulars as the missionary himself supplied. I need hardly say that he was a highly cultured and intelligent gentleman, since only such persons are chosen for missionary work in China.

From inquiries made by me on the 29th of January, 1875, I learnt that they left Ningpo in November, 1872, and travelled thence 130 miles into the interior of the country. In the following September, or about ten months subsequently, the missionary was attacked with diarrhœa, which persisted until expulsion of some of the parasites had occurred. According to the patient’s statements this result, so far, was entirely due to his having been placed on a milk diet; this course of treatment having been recommended by Dr Henderson, of Shanghae. The patient himself always suspected the presence of intestinal worms of some sort or other, although a Japanese doctor laughed at the idea of such a thing. Some other doctor treated this missionary for parasites, administering both male-fern and santonine without effect.

It was not until several months had elapsed that his wife was attacked with diarrhœa. In both cases there was more or less flatus. The motions were white, and there were other indications implying that the liver was affected. Later on, symptoms of indigestion, with heartburn, set in and became very severe. Streaks of blood appeared in the fæces, but there was no dysentery. For the most part these symptoms were attributed to the effects of climate.

When, in the month of February, 1875, I saw the missionary a second time, professionally, I found that all the old symptoms had returned. He had a foul tongue, the surface of the body was cold, he felt chills, and the pulse, though regular, registered ninety-six to the minute. Indigestion, nausea, headache, and diarrhœa had reappeared. Notwithstanding these febrile symptoms, so satisfied was the patient himself that all his ailments were entirely due to the presence of parasites, that I felt inclined to take the same view of his case. Accordingly my attention was principally directed to an effort for their expulsion; and in this view I ordered an aloetic pill followed by a castor-oil emulsion. This having no effect, I subsequently prescribed aloes and assafœtida pills, followed by scammony mixture. The action of the latter drug did not occasion griping, but, although efficient, led only to negative results. I should mention that in the patient’s judgment none of the vermifuges administered to him at any time had exerted any influence in the expulsion of the flukes. He was still thoroughly impressed with the notion that the milk diet, ordered by Dr Henderson, was the sole cause of their expulsion.

As even a missionary could not live by milk alone I insisted upon a more substantial diet. The milk, indeed, had occasionally been supplemented by Liebig’s extract of meat and by light farinaceous food. When I last saw him neither he nor his wife had passed any more flukes, but they did not feel satisfied that no more guests remained. Somewhat improved in general health, the missionary resolved to go back to his duties in China. I expressed my fears, however, that his strength would prove unequal to the work.

From the size and almost leathery texture of the two flukes which were in the first instance submitted to my notice, I at once recognised the species; but as they were spirit-specimens, I requested that if any more examples were obtained they should be sent to me in the fresh state. Fortunately others were brought in a few days, when, from an examination conducted whilst they were still fresh, I was able to make out several details of structure which had hitherto escaped notice. Altogether I secured seven specimens, three of them being in a mutilated condition. In what way these mutilations (as shown by my dried specimens) occurred I have not been able to make out, either by personal observation or by questioning the bearers. Two of the parasites look as though portions had been carefully excised near the centre. The new facts I have gleaned were derived from the examination of two comparatively small specimens, one of which, dried, has, by Prof. Rolleston’s desire, been deposited in the anatomical department of the University Museum at Oxford. When I took occasion to bring some of the new specimens under Mr Busk’s attention, he at once recognised them as referable to the species he had long ago discovered.

The earliest literary notice of _Distoma crassum_ appeared in Dr Budd’s classical treatise ‘On Diseases of the Liver;’ and in it the author correctly stated, from data supplied by Mr Busk, that these human flukes were “much thicker and larger than those of the sheep,” being, it is added, from “an inch and a half to near three inches in length.” The longest of my recent specimens, however, scarcely exceeds two inches, whilst the smallest and most perfect (the one at Oxford) measures less than an inch from head to tail. The greatest width of my broadest specimen is little more than half an inch, or 9/16″. None of the twelve examples that I have examined approach the length of three inches; but Mr Busk assured me that, judging from his recollection, some of his specimens were even longer than that. I fear, nevertheless, that the estimate given in my Synopsis is somewhat exaggerated; at all events it is so for average specimens.

The new anatomical facts made out by me bear reference principally to the reproductive apparatus. What else I have observed is for the most part confirmatory of the statements made by Mr Busk. In particular, his brief account of the position and character of the digestive organs was not only confirmed by my earlier examinations, but is now re-verified. In the representation given in my ‘Introduction’ I showed in dotted outline two large organs which I supposed to be the testes. I distinctly observed radiating lines proceeding from the centre in each; but I could not discover the slightest trace of any limiting border to either organ. I now found in the same position two nearly circular flattened masses with clearly defined limits (_i_, _k_). No doubt could be entertained as to the testicular character of the lower organ (_k_). In the original drawing I further indicated the presence of a third and much smaller globular mass, which I termed the ovary; but what I supposed to represent this organ in the particular specimen from which the accompanying illustration was drawn turns out to be merely a hernial protrusion resulting from injury (_h_). The radiating, broad, and branching seminal ducts are beautifully distinct in one of my specimens, forming the most attractive feature of the parasite’s organisation (_k_). In consequence of injury to the specimen which is here drawn, the upper testis (_i_) displays no seminal tubes. I made out the female reproductive organs with more completeness. In the outline drawing given in my introductory treatise I had indicated the probable position of the uterine folds; reducing the organ to the simplest expression of what I concluded must obtain in the normal condition. My conjecture was perfectly correct. The uterus consists of irregularly folded tubes, which, though here and there apparently branching from a central tube, are in reality folded evenly upon themselves. The oviduct can be distinctly traced to its outlet in the reproductive papilla, which, as usual in true Distomes, is placed in the middle line, immediately above the ventral sucker. In my examination of Mr. Busk’s original specimens I could not find the slightest trace of vitelligene organs; but in my fresh examples I not only obtained proof that these organs were largely developed, but that their limitations could be fixed with accuracy (_g g_). They consisted of two large elongated masses, one on either side of the body, occupying about two thirds of the entire length of the parasite. Their yolk-vesicles were distinctly seen; but the main efferent canals were only here and there traceable. Clearly, the position and character of the yolk-forming glands of this large human fluke are quite unlike those of any of its congeners. This fluke is a remarkably fine species, and, when viewed in the fresh state with a powerful pocket-lens, presents a most striking appearance. I did not observe any cutaneous spines. I found the eggs to present an average long diameter of about 1/200″, by 1/330″ in breadth. They are therefore somewhat smaller than those of the common fluke. In the specimen preserved in the Hunterian Museum there was complete evidence of the presence of an excretory outlet at the caudal extremity; but I did not succeed in finding any trace of the water-vascular system higher up. I have no doubt, however, that it exists.

As regards the affinities of _Distoma crassum_, it is clear that this Trematode has little in common either with the liver-fluke of cattle and sheep (_Fasciola hepatica_), or the still larger species obtained by me from the giraffe (_Fasciola gigantea_). The simple character of the digestive tubes obviously connects it more closely with the lancet-shaped fluke (_Distoma lanceolatum_), the last-named parasite being, as already shown, an occasional resident in the human liver, where its presence, moreover, undoubtedly contributed towards the production of the fatal result.

In my remarks on the missionary’s diet it is hinted that the Ningpo oysters may have played the _rôle_ of intermediary bearers to the parasite in question; and as tending in some measure to strengthen this notion, it should be borne in mind that Mr. Busk’s original fluke-bearer came from the east. It is not improbable that the Lascar host may have partaken of the same particular species of fish or shell-fish that the missionary and his wife partook of. Be that as it may, the frequency of the occurrence of Trematodes and their larvæ in marine mollusks is well known. According to Woodward, several species of oyster are sold in the Indian and Chinese markets. Thus, it would require the skill of a malacologist to determine the particular species of _Ostrea_ to which the Ningpo oysters should be referred.

Mons. Giard is of opinion that the singular larvæ known as _Bucephali_ attain sexual maturity in sharks and dog-fishes; therefore it is extremely unlikely that the _Bucephali_ should have been in any way concerned in the infection of our missionary and his wife; nevertheless there remains the probability that these human bearers swallowed other kinds of Trematode larvæ when they consumed the Ningpo oysters. Moreover, if it should happen that none of the other larvæ occurring in oysters are capable of developing into flukes in the human territory, it yet remains highly probable that some one or other of the various encysted (and therefore sexually immature) Trematodes known to infest marine fishes will turn out to be the representative of our _Distoma crassum_. In this connection we must not forget that the flesh of the _Salmonidæ_ forms the probable source of human _Bothriocephali_; and there is some likelihood that salt-water fishes, if not actually the primary, may become (after the manner explained by M. Giard) the secondary intermediary bearers of fluke-larvæ. At all events, I am inclined to look to the Ningpo oysters, or to some other of the various species of marine shell-fish sold in eastern markets, as the direct source of _Distoma crassum_; for, in addition to the bucephaloid cercarians, we have abundant evidence of the existence of other and more highly developed fluke-larvæ in marine bivalve mollusks.

In this connection I will only further observe that we possess very little knowledge of the parasites which take up their abode in the viscera of savages. This ignorance results partly from the fact that these untutored races, as proved by the statements of Kaschin and others, actually, in the matter of severe symptoms, suffer much less from the presence of intestinal worms than their civilised fellow-men do. The subject is worthy of further attention, but no one, so far as I am aware, has cared to institute the necessary inquiries in a methodical way. I strongly suspect that several of the human parasites which we now consider to be rare would be found to be abundant if by means of post-mortem examinations and other methods of investigation we could be made acquainted with the facts of helminthism as they occur amongst the raw-flesh and fish-eating savage tribes. Of course any person, notwithstanding the utmost care and cleanliness, as in the cases before us, may contract a noxious parasite; nevertheless, speaking generally, it may be said that the measure of internal parasitism affecting any given class of people bears a strict relation to the degree of barbarism shown by such persons in their choice of food and drink, and in their manner of eating and drinking. This statement, if true, is not destitute of sanitary importance; moreover, it applies not alone to ourselves, but also to all the domesticated animals that serve our wants. Cleanliness is just as necessary for their welfare as for our own.

In the spring of 1878 my patients returned from China. They had experienced fresh attacks from the parasite; moreover, one of their children, a little girl, was also victimised by the same species of fluke. Thus, in one family I have encountered three cases of fluke-helminthiasis due to _Distoma crassum_! One of the worms passed by the little girl _per anum_ is now in my possession. It not only shows the upper testis perfectly, but also the many times transversely folded, simple, uterine rosette which is certainly not branched. There are also traces of an organ which I take to be the cirrhus-pouch; but I have never seen the penis protruded externally.

For the purposes of diagnosis I subjoin the following characters. The _Distoma crassum_ is a large, flat helminth varying from an inch and a half to two and a half inches in length, and having an average breadth of five eighths of an inch; it is especially also characterised by its uniform and considerable thickness, combined with the presence of a double alimentary canal which is not branched; the body is pointed in front, and obtusely rounded posteriorly; the integument being smooth and unarmed; the reproductive orifices placed immediately above the ventral sucker; the testes form two large rounded organs, situated below the uterine rosette, and disposed in the middle line, one in front of the other; the uterine folds occupy the front part of the body; near the lateral margins there are two large vitelligene glands, one on either side of the intestinal tube; the excretory organ probably consists of a central trunk with diverging branches, opening below.

BIBLIOGRAPHY (No. 5).--_Budd_, original notice in his ‘Diseases of the Liver,’ 2nd edition, quoted by Lankester in Appendix B to Küchenmeister’s ‘Manual of Parasites,’ p. 437, 1857.--_Cobbold, T. S._, “Synopsis of the _Distomidæ_,” in ‘Journ. of the Proceed. of the Linnean Soc.,’ vol. v, Zool. Div., 1860 (original description p. 5).--_Idem_, ‘Entozoa,’ p. 193, 1864.--_Idem_, “Remarks on the Human Fluke Fauna, with especial reference to recent additions from India and the East,” the ‘Veterinarian,’ April, 1876.--_Idem_, “On the supposed Rarity, Nomenclature, Structure, Affinities, and Source of the large Human Fluke (_D. crassum_),” ‘Linn. Soc. Journ.,’ vol. xii, Zool. Div., 1876, p. 285 _et seq._--_Idem_, “Observations on the large Human Fluke, with notes of two cases in which a missionary and his wife were the victims,” the ‘Veterinarian,’ Feb., 1876.--_Idem_, “The new Human Fluke,” in a letter published in the ‘Lancet,’ Sept., 1875.--_Leidy_, in ‘Proceed. Acad. Nat. Sciences of Philadelphia;’ see also Dr McConnell’s paper quoted below (Bibl. No. 6).--_Leuckart_, l. c., Bd. I, s. 560.--_Weinland_, l. c. (Bibl. No. 2), Appendix, p. 87.

_Distoma Sinense_, Cobbold.--The discovery of this species is due to Prof. J. F. P. McConnell, who “on the 9th of Sept., 1874, found a large number of flukes in the liver of a Chinese, obstructing the bile ducts.” The species measures 7/10″ in length, by 1/7″ in breadth, the eggs being 1/833″ by 1/1666″. Dr McConnell showed in his original memoir that the worm cannot well be confounded with _Fasciola hepatica_, with _Distoma lanceolatum_, or with _D. conjunctum_. In this conclusion he was supported by Dr T. R. Lewis, who examined the specimens with him. In a letter communicated to the ‘Lancet,’ quoted above, I proposed the nomenclature here given; but Prof. Leuckart, unaware of this step, afterwards suggested the terms _Distomum spatulatum_. Later on I received numerous specimens from Calcutta, the examination of which enabled me to confirm the accuracy of the original description. As regards the male organs in the subjoined figure, it will be seen, by comparing the lettering and references, that I have interpreted the facts of structure somewhat differently from Prof. McConnell.

In the month of December, 1874, a Chinese died in the Civil Hospital at Port Louis, Mauritius, whilst he was under the care of Dr William Macgregor, chief medical officer of the Colony of Fiji. The post mortem revealed the presence of a very great number of flukes in the bile-ducts. Dr Macgregor described these parasites with great care, and having favored me with a copy of his manuscript I at once recognised the worms to be identical with the species discovered by McConnell. I also received through Dr Henry Clark, of Glasgow, two Mauritius specimens, which when compared with the Calcutta examples proved to be specifically identical. Dr Macgregor’s paper, communicated to the Glasgow Medico-Chirurgical Society, gives full particulars of the helminthiasis associated with this parasite, whilst both his and Prof. McConnell’s account of the structure of the worm are remarkably complete in details, and well illustrated. It is not a little curious to notice that although these parasites were obtained in countries far removed from China, they were in both instances taken from Chinese; moreover, from the statements of Macgregor, it appears very probable that the parasites in question are a common source of liver disease. Without doubt oriental habits are eminently favorable to fluke infection, for we are now acquainted with four species of flukes whose geographical range is limited to eastern parts.

BIBLIOGRAPHY (No. 6).--_McConnell, J. F. P._, “Remarks on the Anatomy and Pathological relations of a new species of Liver-fluke,” ‘Lancet,’ Aug. 1875; repr. in the ‘Veterinarian,’ Oct., 1875; also in the ‘Lancet,’ March 16th, 1878, p. 406.--_Macgregor, W._, “A new form of Paralytic Disease, associated with the presence of a new species of Liver Parasite (_Distoma Sinense_),” ‘Glasgow Med. Journ.’ for Jan., 1877; also in the ‘Lancet’ for May 26th, 1877, p. 775.--_Cobbold, T. S._, in a note to the ‘Lancet,’ Sept., 1875, and in the Appendix to Macgregor’s paper, p. 15, 1877.--_Leuckart, R._, l. c., Bd. ii, s. 871, 1876.

_Distoma conjunctum_, Cobbold.--The little fluke which I first discovered in the gall-ducts of an American fox (_Canis fulvus_) was fourteen years afterwards obtained from pariah dogs in India by Dr. T. R. Lewis (1872); but it remained for Prof. McConnell to show that this entozoon also invades the human subject (1874). A second instance of its occurrence in man was recorded in 1876. We all figured the worm, and in respect of general details our descriptions for the most part agreed (fig. 56). The worms from the dog and fox gave an average of 1/4″ in length, but the majority of those found by McConnell in man were fully 3/8″ from head to tail.

Writing in the spring of 1876 Dr McConnell says:--“In the ‘Lancet’ for the 21st of August, 1875, I published the description of a new species of liver-fluke found in the bile-ducts of a Chinaman (_sic_) who died in this hospital. Dr Spencer Cobbold has very kindly interested himself in this discovery, and proposed the name of _Distoma Sinense_ for the new fluke. This discovery (in September, 1874) has stimulated me to pay still greater attention to the morbid conditions of the biliary canals in our post-mortem examinations; but, although more than 500 autopsies have been conducted since that date, I have not met with another instance of distomata in the liver until within the last fortnight. On the 9th of January, 1876, in examining the liver of a native patient who had died in the hospital, I again found a large number of flukes in the bile-ducts, and having carefully examined many specimens, I recognise the species as the _D. conjunctum_ of Cobbold. Dr Cobbold discovered this fluke in 1858; but, as far as I am aware, the human liver has never hitherto been found infested by these parasites, and this will give general interest and importance to the following case.”

“Jamalli Khan, a Mahommedan, aged twenty-four, admitted into the hospital on the 25th of December, 1875. He is a resident of Calcutta, and an ordinary labourer (coolie). He states that he had been suffering from ‘fever’ for the last two months, at first intermittent in character, but for the last seven days more or less continued. He is much emaciated and reduced in strength. Complains of pain on pressure over the liver and spleen; the latter can be felt much enlarged, reaching downwards to nearly the level of the umbilicus; the lower border of the liver, however, can only just be felt below the ribs. Temperature on evening of admission 101° F. Conjunctivæ are anæmic, but not jaundiced. Has also a little bronchitis. The fever continued with slight remissions for ten days (January 4th, 1876), the highest diurnal temperature (in the afternoon) varying from 103° to 104° F.; it then abated, but dysentery set in. He began to pass six or eight stools in the twenty-four hours, attended with much griping, and containing varying quantities of blood-tinged, gelatinous mucus. These became more frequent, in spite of treatment, during the next three days, and on the 8th of January he was manifestly sinking; passed his evacuations into the bedclothes, became cold and collapsed, and died in this state that same evening.

“A post-mortem examination was made on the following morning, thirteen hours after death. All the organs of the body were found more or less anæmic, but exhibited nothing remarkable with the following exceptions. The lungs towards their posterior margins and bases were dark, but still spongy and crepitant. The spleen was found greatly enlarged, heavy; capsule tense and stretched; substance soft, reddish brown, irregularly pigmented; weight 1 lb. 13 oz. The liver was of about normal size; its surfaces smooth, the capsule slightly hazy looking. Hepatic substance firm, but abnormally dark, and the bile-ducts particularly prominent and thickened. Numbers of small distomata escaped from the incisions made into the organ, and could be seen protruding from the dilated biliary canals. The gall-bladder was filled with thick greenish-yellow bile, measuring about an ounce and a half, but containing no parasites, and no ova even could be detected on microscopical examination of this bile and of scrapings from the lining membrane of the gall-bladder. The cystic duct was free from obstruction. The condition of the common choledic duct could not so well be ascertained, as the liver had been removed from the abdominal cavity before anything extraordinary had been detected in its condition, but, so far as it could be examined, it was found patent; the duodenal mucous membrane was well bile-stained, and there was evidence of biliary colouring matter in the fæcal contents of the bowels. On carefully dissecting out, and then laying open, the biliary ducts in a portion of the right lobe of the liver (the rest being preserved entire), numbers of distomata were found within them, lying singly, flattened, and generally with the anterior extremity, or “oral sucker,” directed towards the periphery of the organ, the posterior extremity towards its centre; or in twos, threes, or even little groups of fours, variously coiled upon themselves or upon each other. The lining membrane of the biliary canals was found abnormally vascular, its epithelial contents abundant (catarrh?), and, among these, ova could be detected under the microscope. Sections of the liver, hardened and then examined in glycerine, showed fatty infiltration of the lobular structure, but not to any advanced degree; the bile ducts considerably dilated, their walls thick and hypertrophied, but nothing else abnormal, or in any way remarkable. The weight of the liver was 3 lbs. In the transverse and descending colon numerous indolent-looking, shallow, pigmented ulcers were found, and in the rectum others evidently more recent and highly injected. The submucous tissues throughout were abnormally thickened. The intestinal contents consisted of only about three ounces of thin yellowish (bilious) fæcal fluid, with small bits of opaque mucus. This was carefully washed and examined, but no flukes were discovered. About a dozen distomata escaped from the liver on making the primary incisions, and quite twice this number was found subsequently within the biliary canals. Only a portion of the right lobe has, as I have said, been dissected, so that it may be confidently stated that probably not less than a hundred of these flukes must have infested this liver. All were found dead, but it must be remembered that the autopsy was performed thirteen hours after the death of the patient. It is remarkable that in this case, as in the one before described by me, no distomata were found in the gall-bladder. The presence of these parasites in the bile-ducts seems to have led to catarrhal inflammation of their lining membrane and abnormal thickening and dilatation of their walls, but there is no evidence of their having caused sufficient obstruction to produce cholæmia, as in the case just referred to, and no marked pathological change could be detected in the lobular structure of the liver.”

After referring to the anatomical descriptions of the worm, as recorded by myself (in ‘Entozoa’) and by Lewis (in the memoir quoted below), Professor McConnell further observes that the addition of a few more particulars seems necessary for the determination of the identity of the species. He then gives the following characters:

“Body lanceolate, anterior and posterior extremities pointed, the latter obtusely. Surface covered with minute spines or hairs. Average length 3/8″ (three eighths of an inch); average breadth 1/10″. ‘Ventral’ sucker slightly smaller than ‘oral.’ Reproductive papilla or genital orifice placed a little above and to one side of the former. Alimentary canal double and unbranched. Uterine folds and ovary placed in the median line, and above the male generative organs, the latter consisting of two very distinct globular bodies or testes. Ova of the usual type, _i. e._ oval in outline, having a double contour, and granular contents; average length, 1/750″; average breadth, 1/1333″. The only point of note is that the average length of these flukes is greater than that of the same species found by the authors above referred to. The _D. conjunctum_ in the American fox, and in the pariah dog, has an average length of 1/4″; only two or three specimens of this size were found in this liver, and these showed evidences of immaturity; a few were found 1/2″ in length; but the great majority exactly 3/8″. The anatomical characters are otherwise precisely identical.”

Professor McConnell concludes his communication by a remark in reference to the common source of infection shared by mankind and dogs in India. The occurrence, however, of this entozoon in an American red fox points to a very wide geographical distribution of the species. It is hardly likely that the fox, though dying in the London Zoological Society’s Menagerie, should have contracted the parasite in England. In the second half of this work I shall reproduce my original drawing (fig. 56) from the ‘Linnean Transactions;’ but I may refer to my Manual (quoted below) for a reproduction of McConnell’s figure. In my original specimens the integumentary spines had fallen, probably as a result of post-mortem decomposition.

BIBLIOGRAPHY (No. 7).--_Cobbold, T. S._, “Synopsis of the Distomidæ” (l. c.), 1859; and in “Further Observations on Entozoa, with experiments,” ‘Linn. Trans.,’ vol. xxiii (tab. 33, p. 349), 1860.--_Idem_, “List of Entozoa, including Pentastomes, from animals dying at the Zool. Soc. Menagerie between the years 1857-60,” ‘Proceed. Zool. Soc.,’ 1861.--_Idem_, ‘Entozoa,’ p. 20, pl. ii, 1864; and in “Manual of the Internal Parasites of our Domesticated Animals,” p. 81, 1873.--_Lewis, T. R._, and _Cunningham, D. D._, in a footnote to their ‘Microscopical and Physiological Researches,’ Appendix C., ‘Eighth Ann. Rep. of the San. Comm. with the Govt. of India,’ p. 168, Calcutta, 1872.--_McConnell, J. F. P._, “On the _Distoma conjunctum_,” in the ‘Lancet’ for 1875-76, quoted above; reprinted in the ‘Veterinarian,’ 1876; also (a second case) in the ‘Lancet’ for March 30th, 1878, p. 476.

_Distoma heterophyes_, Von Siebold.--This minute parasite, measuring only 3/4 of a line in length, was discovered by Dr Bilharz, of Cairo, in the intestines of a lad, post-mortem, in the year 1851. A second similar instance occurred, when several hundred examples were collected and afterwards distributed amongst the helminthologists of Europe. Through the kindness of Leuckart two of the worms eventually reached myself. From one of these the accompanying figure was drawn. For the purpose of supplying a full diagnosis I have elsewhere described this worm as presenting an oblong, pyriform outline, attenuated in front, and obtusely rounded behind; body compressed throughout, the surface being armed with numerous minute spines, which are particularly conspicuous (under the microscope) towards the head; oral and ventral suckers largely developed, the latter being near the centre of the body, and about twice the diameter of the former; pharyngeal bulb distinct and separate from the oral sucker, and continued into a long œsophagus, which divides immediately above the ventral acetabulum; intestinal tubes simple, gradually widening below and terminating near the posterior end of the body; reproductive orifices inconspicuous, but evidently placed below and a little to the right of the ventral sucker, at which point they are surrounded by a special accessory organ, resembling a supernumerary sucker; uterine folds numerous and communicating with small but conspicuously developed vitelligene glands; testes spherical and placed on the same level in the lower part of the body; ovary distinct; aquiferous system terminating inferiorly in a large oval contractile vesicle, the latter opening externally by a central _foramen caudale_.

Apart from its minuteness, moreover, this trematode is especially characterised by the possession of a very remarkable apparatus surrounding the reproductive orifices. It consists of an irregularly circular disk, measuring 1/125″ in diameter, and having a thick-lipped margin, which supports seventy fish-basket-like horny ribs comparable to the claw-formations seen in the genus _Octobothrium_. According to Bilharz these ribs give off five little branches from their sides, but Leuckart could not see them in his specimens. Leuckart estimated the length of these horny filaments to be 1/1250″, whilst their breadth was 1/3570″. On the whole we may regard this organ as a complicated form of “holdfast” designed to facilitate or give efficiency to the sexual act. I may here also state that this structure is by no means unique; for, if I mistake not, it exists in an equally developed degree in the young trematode which Dr Leared found infesting the heart of a turtle. Leared believed that he had found an ordinary distome; an opinion to which I could not give my assent, seeing that the organ described by him as a “folded, ventral sucker” presented a very different aspect to the oral sucker displayed by the same animal. Without doubt, however, the organ in his so-called _Distoma constrictum_ is analogous to the supplementary “holdfast” existing in _Distoma heterophyes_. The views which I originally advanced as to the source and condition of the parasite are probably correct.

As regards the structure of _Distoma heterophyes_, I have only to add that a special set of glandular organs is situated on either side of the elongated œsophagus, but the connection between these organs and the digestive apparatus has not been clearly made out. Leuckart compares them to the so-called salivary glands found in _Distoma lanceolatum_, and says, “The presence of such a glandular apparatus is also indicated by the more ventral position of the oral sucker, and the development of the cephalic margin.” The conspicuous contractile vesicle terminating the excretory system is developed to an unusually large extent, exhibiting in its interior multitudes of the well-known active molecular particles. Lastly, I have only to add that the eggs of _Distoma heterophyes_ measure 1/990″ in length by 1/666″ transversely.

BIBLIOGRAPHY (No. 8).--_Bilharz_, “Beitrag zur Helminth. humana,” ‘Zeitsch. für wissenschaftl. Zool.,’ s. 62, 1851.--_Cobbold_, ‘Entozoa,’ p. 195, 1864.--_Küchenmeister, F._, ‘Parasiten,’ 1855, s. 210, Eng. edit., p. 276, 1857.--_Leared_, “Description of _Distoma constrictum_,” ‘Quarterly Journal of Micros. Science,’ new series, vol. ii, 1862.--_Leuckart, R._, l. c., s. 613, 1863.--_Moquin-Tandon_, on the Genus _Fasciola_, l. c., 1861.--_Weinland_, on _Dicrocœlium_, l. c., p. 86, 1858.

_Distoma ophthalmobium_, Diesing.--There is every reason to believe that the small flukes found by Gescheid and Von Ammon in the human eye were sexually immature worms, but since it cannot be decided as to what adult species they are referable I prefer to notice them under the usual title. Possibly these eye-worms may be referred to _D. lanceolatum_, as suggested by Leuckart. However that may be, I deem it unnecessary to repeat the details recorded in the treatises quoted below. The largest examples measured only half a line or about one millimètre in length.

BIBLIOGRAPHY (No. 9).--_Cobbold_, ‘Entozoa,’ p. 191.--_Gescheid (D. oculi humani)_, in Von Ammon’s ‘Zeitsch. f. Ophth.,’ iii, and also in Ammon’s ‘Klin. Darstell. d. Krankheit d. Menschl. Auges.,’ vols. i and iii.--_Küchenmeister_, Eng. edit., p. 287.--_Leuckart_, l. c., s. 610.--_Nordmann (Monostoma lentis)_, “Mikr. Beitr.,” Heft. ii, ‘Vorwort,’ s. ix, 1832.

_Tetrastoma renale_, Chiaje; _Hexathyridium pinguicola_, Treutler; and _H. venarum_, Treutler.--Whether these forms are good species or not, the fact that they were genuine parasites cannot, I think, be disputed. The first-mentioned measured five lines in length, and was found by Lucarelli in the urine. The second, eight lines long, was found by Treutler in a small tumour connected with the ovary. The third, measuring three lines in length, was twice found in venous blood, and twice in the sputum of patients suffering from hæmoptysis.

BIBLIOGRAPHY (No. 10).--_Delle-Chiaje_, ‘Elmintografia Umana,’ 1833.--_Bremser_ (l. c., Bibl. No. 2), s. 265, 1819.--_Cobbold_, ‘Entozoa’ (p. 204, et seq.).--_Dujardin_ (l. c., Bibl. No. 2), s. 265, 1819.--_Treutler_, ‘Obs. Path. Anat. ad Helm. Corp. Humani,’ p. 19, 1793.--_Zeder_, ‘Anleitung zur Naturg. der Eingeweidewürmer,’ s. 230, 1803.

_Amphistoma hominis_, Lewis, and McConnell.--The original account of this species is based upon two finds. The first series of specimens was procured from Dr J. O’Brien, of Gowhatty, and the second set from the Pathological Museum of the Calcutta Medical College. Dr O’Brien and Dr Curran together procured their specimens, post-mortem, from an Assamese. There were hundreds of worms present in the vicinity of the ileo-colic valve. The museum specimens were procured from a patient who died at the Tirhoot gaol hospital in 1857. They were (say the authors) presented to the museum by Dr Simpson, and in the catalogue their history was briefly recorded as follows:

“The cæcum of a native prisoner who died from cholera in the Tirhoot gaol hospital, with a number of peculiar and, probably, hitherto unrecognised parasites, found alive in that part of the intestinal canal.” (_Presented by Dr Simpson through Professor E. Goodeve._)

In continuation of their narrative, Drs Lewis and McConnell go on to say that, “with reference to this preparation, the following very interesting particulars from the ‘Annual Jail Report of Tirhoot’ for 1857 have been very kindly placed at our disposal by the Surgeon-General, Indian Medical Department. The prisoner, Singhesur Doradh, aged 30, was attacked with cholera on the 13th, and died on the 14th of July, 1857. Had not been in hospital previously, and was employed in cleaning the jail.”

The post-mortem examination was made three hours after death:--“Colon externally livid, contracted; contains a little serous fluid with flakes of mucus. Mucous membrane healthy except venous injection. In the cæcum and ascending colon numerous parasites like tadpoles, alive, adhering to the mucous membrane by their mouths. The mucous membrane marked with numerous red spots like leech-bites from these parasites. The parasites found only in the cæcum and ascending colon, none in the small intestines.” This description is by Dr Simpson, who adds, “I have never seen such parasites, and apparently they are unknown to the natives. They are of a red colour, size of a tadpole, some young, others apparently full grown, alive, adhering to mucous membrane,--head round, with circular open mouth, which they had the power of dilating and contracting. Body short and tapering to a blunt point.”

Drs Lewis and McConnell’s description of the worm is too long to be quoted in full. The parasites measure 1/5″ to 1/3″ in length, by 1/8″ to 1/6″ in breadth. Science is much indebted to these eminent observers for having unearthed the museum specimens and for recording the facts they could gather. From a zoological point of view the most interesting fact connected with Lewis’s amphistome is the existence of a gastric pouch. This structure brings these human _Masuri_ into close relation with the equine parasite which I have named _Gastrodiscus Sonsinoii_, and which will be found illustrated in this work (fig. 62). In short, Lewis’s worm appears like a transition form; the absence of gastric supplementary suckerlets separating it from the new generic type.

BIBLIOGRAPHY (No. 11).--_Lewis, T. R., and McConnell, T. F. P.,_ “_Amph. hominis_; a new parasite affecting Man,” ‘Proceedings of the Asiatic Society of Bengal,’ Aug., 1876.

_Bilharzia hæmatobia_, Cobbold.--This remarkable parasite was discovered by Bilharz in 1851. It was subsequently found by myself in an ape (1857); other species of the same genus having since been detected by Sonsino in the ox and sheep (1876). The human examples were originally obtained from the portal system of blood-vessels. Afterwards they were obtained by Bilharz, Griesinger, and others, from the veins of the mesentery and bladder. It was shown that they were not only associated with, but actually gave rise to a formidable and very common disease in Egypt.

In 1864 Dr John Harley made the interesting announcement that he had discovered specimens of this singular genus in a patient from the Cape of Good Hope. He also showed that the entozoon was the cause of the _hæmaturia_ known to be endemic at the Cape. Harley believed his parasites to represent a new species (_Distoma capense_), but in this view I showed that he was mistaken. His admirable contribution, nevertheless, served not only to establish the wide range of this parasite on the African continent, but also to throw much light upon the subject of endemic helminthiasis. As this worm forms an almost altogether exceptional type of fluke-structure, it became necessary to supersede the original nomenclature proposed by Bilharz and Von Siebold (_Distoma hæmatobium_). Accordingly I proposed the term _Bilharzia_, whilst other helminthologists subsequently proposed various titles (_Gynæcophorus_, Diesing; _Schistosoma_, Weinland; _Thecosoma_, Moquin-Tandon). On various grounds, and chiefly on account of priority, most writers have at length definitely accepted the nomenclature which employed the discoverer’s name for generic recognition.

The _Bilharzia hæmatobia_ may be described as a trematode helminth in which the male and female reproductive organs occur in separate individuals; the male being a cylindrical vermiform worm, measuring only half an inch or rather more in length, whilst the female is filiform, longer, and much narrower than the male, being about four fifths of an inch from head to tail; in both, the oral and ventral suckers are placed near each other at the front of the body; in the male the suckers measuring 1/100″, in the female 1/314″ in diameter; in either, the reproductive orifice occurs immediately below the ventral acetabulum. The comparatively short, thick, and flattened body of the male is tuberculated and furnished with a _gynæcophoric_ canal, extending from a point a little below the ventral sucker to the extremity of the tail; this slit-like cavity being formed by the narrowing and bending inwards of the lateral borders of the animal, the right side being more or less completely overlapped by the left margin of the body; caudal extremity pointed; intestine in the form of two simple blind canals. Female with a cylindrical body measuring only 1/312″ of an inch in thickness in front of the oral sucker; lodged in the gynæcophoric canal of the male during the copulatory act; thickness of the body below the ventral acetabulum being about 1/357″, and at the lower part 1/96″; surface almost smooth throughout; intestinal canals reunited after a short separation to form a broad, central, spirally twisted tube extending down the middle of the body; vitelligene and germigene canals combining to form a simple oviducal canal, which is continued into a simple uterine tube, finally opening near the lower margin of the ventral sucker; eggs pointed at one end, or furnished with a projecting spine near the hinder pole.

The study of the structure and formation of the contents of the ova possesses great interest. When fully developed the eggs are oval, measuring from 1/180″ to 1/160″ in length, with an average transverse diameter of 1/325″. Some are a trifle larger, others smaller. Occasionally one encounters narrow specimens, and also aberrant forms presenting a pear-shaped outline. I have met with eggs not exceeding 1/250″ in their long diameter, and 1/500″ transversely, whose yolk-contents had already arrived at an advanced stage of segmentation.

The shell is transparent, of a brown colour, and free from any markings, lines, or sculpturing. One pole of the shell is invariably narrower than the other, and usually presents a more or less pointed extremity (fig. 8). This narrow end commonly displays a sharp, projecting, beak-like spine, which, at its base, constantly rests upon the centre of the pole of the shell, but occasionally it is eccentrically placed (fig. 8_a_). In some few examples the spine is removed to a little distance from the actual extremity of the shell; but even in these instances, so far as my observations go, its apex always projects beyond the level of the curved end of the pole. Now and then the spine is altogether absent (fig. 8_b_); and when present it is, as already hinted, very unequally developed. In size the spine ranges from a mere point, having an extreme length of only 1/8000″, up to the comparatively large magnitude of 1/2500″ lengthways.

According to the best evidence there is no good ground for asserting the existence of any specific differentiation between the parasites coming from the Cape and Egypt respectively.

Taking a more extended view of the significance of these singular chorional spines, I think we may here recognise the early efforts of Nature, so to speak, to form or evolve a special organ, which, in the eggs of certain other parasites, becomes capable of attaining a relatively prodigious degree of development. To me it seems that the little process in question is a kind of rudimentary holdfast; and, as such, it may be reckoned as the homologue of a variety of egg-appendages. Eleven years ago Mr Edwin Canton discovered some curious ova attached to the conjunctiva of a turtle’s eye. I had no hesitation in pronouncing them to be referable to some ectozoon or entozoon belonging to one or other of the allied genera _Polystoma_, _Tristoma_, _Octobothrium_, and _Dactylogyrus_. Now, whilst the Bilharzia ova display only a solitary and imperfectly developed holdfast, placed at one end of the shell, the singular eggs described by Mr Canton develop organs of anchorage at both extremities. Parasitic ova exhibiting analogous processes, spines, and filamentary appendages at both poles, have been observed in various species of parasite--as, for example, in _Monostoma verrucosum_ infesting the fox, in _Tænia cyathiformis_ infesting the swallow, in _Tænia variabilis_ of the gambet, in _Octobothrium lanceolatum_ attached to the gills of the common herring; and in _Polystoma appendiculata_, from the branchiæ of various marine fishes. Eggs of parasites which, like _Bilharzia_, are furnished with a single appendage, may likewise be seen in the ova of different species of _Dactylogyrus_ infesting the gills of the pike. In the more strongly pronounced developments it is easy to perceive how admirably these outgrowths are adapted to the necessities of the different species of parasite to which they are severally referable; and, even in the case of _Bilharzia_, the trifling amount of anchorage furnished by a projecting point is not absolutely thrown away. The resistance will also be greater where the spine is situated a little on one side of the pole of the egg, which seems to need steadying during the violent struggles of the embryo to escape from its temporary abode.

When any number of ova are removed from the urine and examined, it will be found that a large proportion of them contain embryos in an advanced stage of larval growth. The structural appearances presented by the embryos whilst still in the eggs are remarkably uniform; since, in all, the yolk appears to have resolved itself into a mass of rounded sarcode-globules, one or two of these particles being conspicuously larger than the rest (fig. 12). At this stage, except towards the cephalic division of the larva, no tendency to differentiation is perceptible; but some time after the embryo has escaped, one may notice elongated masses of sarcode formed by the coalescence of the globules. Whilst still in the egg, one end of the primitive embryonal mass becomes gradually narrowed, cilia at the same time appearing. This part becomes the future head, eventually acquiring the form of a cowl. Whatever form the body of the embryo may display after extrusion from the shell, the head retains its conical shape, the cone itself being narrowed or widened only when the larva is subjected to abnormal conditions (fig. 14). Whilst the head is undergoing development within the shell, one, two, or sometimes three, pyriform masses make their appearance within the cone; and after the embryo has escaped, these structures become more marked (fig. 10). The sarcode-globules refract light strongly; and, when the larva is not compressed in any way, they move freely within the somatic cavity. In well-developed embryos, whilst still in the egg, the cilia are observed to clothe every part of the larva except the oral papilla. This minute nipple-like projection measures about the 1/3000 of an inch transversely, forming a very simple kind of unarmed proboscis. When the head of the free embryo is viewed from above, the proboscis looks like a central ring surrounded by a series of regular folds, which radiate outwards like the spokes of a wheel. The ridges thus formed support numerous cilia, these latter projecting at the circumferential margin of the cephalic cone in such a way as to present the figure of a star. Dr Harley has admirably represented this character, which is shared by many other parasitic larvæ. Throughout the greater part of the time, whilst the embryo is still resident within the egg, the broad neck or base of the cephalic cone forms a fixed point of resistance by its firm attachment to the inner wall of the shell; and this structural union, so long as it remains intact, enables the embryo to move not only its head and body from side to side synchronously, but also each part independently. When the time for final escape is drawing near, the vigorous movements of the cone-shaped head seem chiefly concerned in loosening the membranous connection just referred to; and when, at length, the ciliated animalcule has succeeded in overcoming this first difficulty, it is ludicrous to witness its frantic efforts to find an opening in the shell. While thus partially liberated, it will rush to and fro from one pole of the egg to the other, performing a series of summersaults, and at the same time occasionally rolling itself over laterally. This activity becomes gradually more and more violent, until at length its excitement is worked up into a sort of frenzy. I have many times watched these performances, which, however, are only to be seen within those ova whose shells, for some reason or other, refuse to yield to the earlier and ordinary efforts of the prisoner. In all cases where these phenomena are witnessed the eye readily detects a number of small free globules between the embryo and the inner wall of the shell (fig. 13). These minute particles are likewise tossed about tumultuously during the rapid rotatory movements of the imprisoned larva. Except as regards their size, these globules do not differ in character from the sarcodic contents of the animalcule. They are probably superfluous detachments from the primitive yolk-mass, but it is possible that they may afford some aid in the final breaking up of the shell. Whilst the embryo remains fixed its tail is usually directed towards the narrower or spine-bearing pole of the egg, but in a few instances I have seen this position reversed. As regards the precise mode of emerging from the shell, and the time occupied by the larva in freeing itself, there are several points of interest. Speaking generally, the purer the medium into which the ova are transferred, the more rapid will be the movements of the larvæ. To give an example of observed facts in relation to the rapidity of development, I cite the following:--“On the 20th of August, 1870, I placed twelve eggs of _Bilharzia_ under the microscope. The medium in which they were immersed consisted of eight parts of ordinary drinking water to one of urine. At the expiration of seventeen minutes the first-born made its escape. In the course of another minute two more emerged. In twenty-six minutes the fourth, in twenty-eight the fifth, in thirty-two the sixth, in thirty-four the seventh, in thirty-seven the eighth, in thirty-eight the ninth, in forty the tenth, in forty-three the eleventh, and in forty-six minutes the twelfth, respectively made their appearance.”

Now, this rapid mode of birth and emergence from the shell is very much more striking in the case of eggs which are placed in perfectly pure water; for, whilst the eggs are still in the urine, there appears to be neither the power nor the inclination on the part of the embryo to escape; but, on isolating and placing them in suitable conditions, their behaviour is even more remarkable. In a space of less than two minutes I have repeatedly seen the hitherto motionless embryo alter its shape by contractions, become violently agitated, and burst out of its shell in the condition of a free-swimming animalcule. Moreover, it is worthy of remark that the eggs and larvæ of _Bilharzia_ soon perish in stale urine. “On the 16th of August, 1870, I placed about a thousand eggs in a quart of fountain-water, to which only a drachm or rather less of urine had been added. At the expiration of forty-eight hours not a single living embryo could be found. I subsequently ascertained that I could not keep the embryos alive for twenty-four hours in any water in which I had introduced the smallest trace of mucus, blood-corpuscles, urinary crystals, or decomposing matters of any kind. All sorts of reagents speedily killed the larvæ. Mere discoloration by carmine solution, or by the addition of a drop of the solution of permanganate of potash, instantly caused them to assume grotesque and unnatural shapes (figs. 13 and 14), death sooner or later following as a result of the disintegration and resolution of their delicate bodies into mere sarcode-masses. Still more rapidly poisonous effects were produced by the addition of a little sherry or alcohol. In solutions where the amount of spirit did not exceed one part of spirit, proof strength, to fifty parts of water the effect was the same.”

The development of the larva is equally well accomplished in distilled water, in well-water, and in brackish water. In pure sea-water the process goes on less satisfactorily. It was found, indeed, that the addition of slightly saline water to ciliated embryos, which were on the point of expiring in fresh water, had the effect of reviving them for a time. These facts have an important practical bearing.

I have thus shown that the escape of the embryo is by no means the slow process that Bilharz has described. Almost invariably the shell bursts by a longitudinal slit extending over fully two thirds of its long diameter, the first point of rupture being commonly situated midway between the spine and the centre of the shell. In normal births, so to speak, the head of the animalcule emerges first; but occasionally the animal escapes sideways, and I have even seen the embryo extricate itself tail foremost. Not unfrequently it has a difficulty in detaching itself from the shell, in which case the egg is whirled round and round by the half-freed prisoner (fig. 15). The lodgment of the spine, however, against any foreign substance affords the necessary leverage for ensuring escape.

The larva never displays its proper elongated, spindle-shaped, or cylindro-conical figure, until some short time after its escape from the shell; and, as a consequence of this, its powers of locomotion are less marked at first than they are subsequently. At the time of extrusion the larvæ are commonly more or less hour-glass shaped (fig. 11); this particular form being sometimes retained for many minutes or even for an hour. Usually the larvæ have a tendency to acquire their normal shape immediately after quitting the shell; the oval, pear-shaped, and variously contracted forms gradually merging into the characteristic cone-shaped animalcule (fig. 10). In their fully developed condition, they exhibit the most lively movements; and to witness several hundreds of them rushing about with unceasing activity is a curious sight. The phenomenon, moreover, loses none of its interest from the consideration that only a few hours, or it may have been minutes, previously, these now actively gyrating animalcules were lodged _in ovo_ within the blood-vessels of their human host. From persons who are infested, myriads of these eggs of _Bilharzia_ daily make their escape during the act of micturition; and, when this act is accomplished by the host out-of-doors, it is easy to perceive how readily the ova may be subjected to conditions favorable to the development of larvæ. The direct passage of the urine into any considerable receptacle of natural or fresh water would in a few minutes ensure the hatching of all the eggs; and in the absence of any such direct aid to development, the accidental occurrence of a shower of rain would, in all localities where the _Bilharzia_ disease is endemic, readily transfer the ova into ditches, ponds, rivers, lakes, and ultimately, perhaps, even into the sea itself.

The behaviour of the embryo under the action of reagents of various kinds is remarkable. Thus, when on the 5th of Sept., 1870, I placed some ova in brackish water, of the strength of two parts of fresh water to one of pure sea-water, their contents were readily developed, though the escaping embryos did not swim vigorously. When again I placed some other eggs in pure sea-water, their contained embryos became instantly transfixed, the vibratile cilia of the head being rigid and motionless. At first I naturally concluded that the embryos were killed outright; but, to my great surprise, the shock passed away in about half an hour, when they revived and were soon afterwards hatched. One of the larvæ thus set free carried off several of the loose intra-chorional globules which had, during the period of transfixion, become firmly adherent to the ends of the caudal cilia. Here I may remark upon a decided difference observable between the cilia of the head and body respectively. The former are at all times vibratile, active, and conspicuous, whilst the latter are more delicate, capable of comparatively little motion, and partaking more of the character of fine setæ. In length their general measurement varies from 1/2500″ to 1/2000″. The action of pure sea-water on the free animalcules, previously immersed in fresh or brackish water, was equally striking. All, without exception, immediately became paralysed and almost motionless; nevertheless, on again adding fresh water, several entirely recovered. It is worthy of notice that in these cases the cephalic cilia furnished the first indications of returning viability. I was particularly struck with the behaviour of one embryo, which, under the stimulus of the sudden shock, retracted its cone-shaped head almost entirely within the general cavity of the body (fig. 14, lower specimen). In their moribund condition, whatever shape the embryo retained, the sarcodic contents gradually faded away; the outline of the creature, however, becoming more marked (fig. 16). Usually the body of the animalcule became elongated whilst expiring in sea-water. Under other circumstances the embryo frequently bursts; the sarcodic contents escaping in the form of amœba-like bodies and the cilia retaining their powers of movement long after all traces of the sarcode have disappeared.

The larvæ of _Bilharzia_ closely resemble those of _Fasciola hepatica_, which latter may be appropriately noticed in this place. The ciliated embryo of the common liver fluke has the form of a long cone inverted; the anterior end or head being flatly convex. In the centre is a short proboscis-like papilla destitute of cilia (fig. 17). The general covering of cilia rests on a well-defined granular epidermis; this latter being succeeded by a dense peripheral layer of large nucleated cells, each of them measuring about 1/2500″ in diameter. The epidermis measures 1/6250″ in thickness. In the central mass of parenchyma no internal organs are recognisable, but Leuckart observed indications of a canal which he thought might open at the tail, though the opening itself was not actually visible.

As long as the ciliated covering remains intact the embryo, like other animalcules, displays great activity, whirling round and round on its own axis, and also describing gyrations and circles of different degrees of range in the water, the latter movements being accomplished by bending the body upon itself to a greater or lesser curvature. The embryos of _Bilharzia_ and other infusoria exhibit the same behaviour, and, as Leuckart observes, when these embryos knock against any obstruction, they pause after the blow, as if to consider the nature of the substance they have touched. As in the case of fluke embryos generally, the ciliated covering eventually falls off and the embryo reassumes a more or less oval figure, at the same time changing its swimming mode of progression for the less dignified method of creeping. In the free ciliated condition the embryo of the common liver-fluke measures, according to Leuckart, 1/190″ in length, the anterior broad end being 1/500″. The cilia have a longitudinal measurement of 1/1388″.

According to the observations of Dr Willemoes-Suhm, the cilia of the embryos of the _Distoma megastoma_ are limited to the anterior pole of the body. This is also the arrangement, as Leuckart first pointed out, in _Distoma lanceolatum_ (fig. 18). On the other hand, Pagenstecher has shown that the embryos of _Distoma cygnoides_ and _Amphistoma_ (_Diplodiscus_) _subclavatum_ are ciliated all over, an observation which, as regards the latter species, has been confirmed by Wagener and others. Dr Pagenstecher’s original statement to the effect that “intrachorional germs of trematodes offer no distinctive characters,” must, therefore, in the present state of our knowledge, be accepted as a general conclusion admitting of many exceptions. In the early stages of development the embryo of _Distoma lanceolatum_ occupies the centre of the egg, and according to Leuckart has its conical head invariably directed towards the upper pole of the shell, or, in other words, to that end of the egg which is furnished with a lid-like operculum. Leuckart describes the embryo itself as “finely granular and armed at the tip with a dagger-like spine, which, with the simultaneous displacement of the adjacent granular mass, can be pushed forward and drawn back again.” Besides this so-called cephalic granular mass, there are within the embryonic body two other granular masses widely separated from each other, but occupying the posterior half of the embryo. These Leuckart supposes to be the rudiments of a future brood, to be developed at the time when the free embryo shall have lost its ciliated swimming apparatus, shall have bored its way by means of the cephalic spine into the tissues of a mollusk, and shall have become metamorphosed into a sac-like larva (Nurse, Sporocyst, or Redia, as the case may be). Whatever be the full significance of these internal developments, we have at least satisfactory evidence that the complete and free embryo is a globe-shaped animalcule, having the anterior third or cephalic end of the body covered with cilia, and armed with a central boring spine. In consequence of this limitation of the ciliated covering, its swimming movements are less vivacious than those of the embryo of _Fasciola hepatica_; it will, therefore, probably take up its residence in a less active host than that chosen by the embryo of Fasciola, selecting one of those mollusks which either move slowly or are prone to keep at the bottom of the water. The mature eggs have a length of 1/625 to 1/555 of an inch, and a breadth of 1/833″. The long diameter of the free embryo varies from 1/990″ to 1/833″, the transverse diameter being 1/1562″. Whilst the embryos were still in the egg Leuckart could see no ciliary motion. With most observers, both the ciliary apparatus and the boring spine appear at this stage to have altogether escaped observation.

As regards the intimate structure of the ciliated embryo of _Bilharzia hæmatobia_, I have further to observe that, shortly after its extrusion from the shell, the hitherto loose, globular sarcode particles coalesce. This is apparently a preliminary step towards the subsequent differentiation process. Respecting the pedunculated blind sacs formed within the head, I think that we must regard the largest one as representing the stomach of the larva in its future cercarian stage. Under the 1/12″ objective I distinctly recognised, in the cavity of the central blind sac, numerous highly refracting granules, the diameter of which averaged not more than 1/12000″. The rudimentary stomach is often traceable whilst the larva is still within the egg. It measures about 1/500″ in length, including the peduncle, and 1/14000″ in breadth. The width of the narrow stalk does not exceed 1/9000″. The other two-stalked bodies appeared to have the character of _lemnisci_. They were occasionally well seen whilst the embryo was still within the egg. As regards the integument, it is easy to recognise two layers. In careful adjustments of the focus the inner wall of the transparent dermis presents a beaded appearance. These minute and regular markings do not undergo alteration during the contractions of the body of the larva.

A highly developed water-vascular system exists in these little animalcules. On many occasions I saw traces of this set of vessels, and in several instances I obtained a most satisfactory view of the entire series of branches. Anxious to receive confirmation of my discovery, I demonstrated the existence of these vessels to a skilled microscopist--the late Mr J. G. Pilcher, of H. M. Army. In the briefest terms it may be said that the water-vascular system of _Bilharzia_, in the larval condition, consists of two main stems, which pursue a tortuous passage from head to tail, and which, in the course of their windings, give off several anastomosing branches (fig. 19). As also obtains in the corresponding larvæ of _Diplodiscus subclavatus_, there is no excretory outlet visible at the tail.

Encouraged by the experiences and determinations of Pagenstecher, Filippi, Wagener, Leuckart, and others, I sought for the intermediate hosts amongst fresh-water mollusks and small crustacea. Failing of success in these, it occurred to me that the larvæ of _Bilharzia_ might normally reside in fluviatile or even in marine fishes. This latter idea seems also to have struck Dr Aitken. In an appendix to his ‘Report to the Army Medical Department for 1868,’ dated from Netley, Nov., 1869, he gives a figure of a nurse-form, which he terms a cercaria, from the tail of a haddock--suggesting for _Bilharzia_ some genetic relation. Dr Aitken also extends his views in reference to certain larval trematodes alleged to have been found in the so-called Delhi boils and Lahore sores. These parasitic forms have, however, been shown by Dr Joseph Fleming to be nothing more than altered hair-bulbs (‘Army Med. Reports,’ 1868-69).

In regard to the flukes from the haddock, I have satisfied myself that these immature trematodes from the nerves of the cod-tribe can have no genetic relation with _Bilharzia_; and I think it due to Dr Maddox to say that I accept his conclusion respecting them. In his paper (‘Micros. Trans.,’ vol. xv, 1867, p. 87) he offers strong proof that the so-called _Distoma neuronaii Monroii_ of the haddock (_Morrhua æglefinus_) is the juvenile condition of _Gasterostoma gracilescens_ of the angler (_Lophius piscatorius_).

I am sorry to have to state that all my experiments proved negative. I tried to induce the ciliated embryos to enter the bodies of a variety of animals, such as Gammari, Dipterous larvæ, Entomostraca, Lymnæi, Paludinæ, different species of Planorbis, and other mollusks; but neither in these, nor in Sticklebacks, Roach, Gudgeon, or Carp, did they seem inclined to take up their abode.

The very peculiar and formidable helminthiasis produced by this parasite has been thoroughly investigated by Griesinger and Bilharz, and it has been fully described in the standard works of Küchenmeister and Leuckart. My own case from Natal also supplied many interesting clinical facts which were published in my ‘Lectures on Helminthology,’ quoted below. The comparative prevalence of this disorder in Egypt is well established. Symptomatically, its principal feature consists in a general disturbance of the uropoietic functions. Diarrhœa and hæmaturia occur in advanced stages of the complaint, being also frequently associated with the so-called Egyptian chlorosis, colicky pains, anæmia, and great prostration of the vital powers. The true source of the disorder, however, is easily overlooked unless a careful microscopic examination be made of the urine and other evacuations. If blood be mixed with these, and there also be a large escape of mucus, a minute inspection of the excreta will scarcely fail to reveal the presence of the characteristic ova of _Bilharzia_. Besides the increase of mucus secretion, there may even be an escape of purulent matter, showing that the disorder has far advanced. The patient’s constitution eventually becomes undermined; pneumonia often sets in, and death finally ensues. On making post-mortem examinations the following pathological facts come to light. In cases where the disease has not advanced very far, minute patches of blood-extravasation present themselves at the mucous surface of the bladder, but in more strongly pronounced cases the patches are larger or even confluent. In some instances there are villous or fungus-like thickenings, ulceration and separation of portions of the mucous membrane, with varying degrees of coloration, according to the amount of the extravasation, which becomes converted into grey, rusty-brown, or black pigment deposits. A gritty or sandy deposit is often superimposed, consisting of ordinary lithic-acid grains mixed with eggs and egg-shells. Eggs are readily detected in the urine, these having escaped from the ruptured vesical vessels. The lining membranes of the ureters and renal cavities are also more or less affected; the kidneys being frequently enlarged and congested. It must, however, be borne in mind that in all these organs the true seat of the disorder is the blood, which forms the proper habitat of the _Bilharzia_; and this being the case, the worms as well as their escaped eggs may be found in any of the vessels supplying the diseased organs. In one instance, quoted by Leuckart, Griesinger found a number of empty eggs in the left ventricle of the heart, and from this circumstance it was supposed that they might be carried into various important organs, or even plug up the larger vessels. As before stated, however, the parasites are more particularly prevalent in the vessels of the bladder, mesentery, and portal system. The effects upon the intestinal mucous membrane are, in most respects, similar to those occurring in the urinary organs. Blood extravasations, with thickening, exudation, ulceration, and fungoid projections, appear in and upon the intestinal mucous and submucous tissues; these appearances, of course, being more or less strongly marked according to the degree of infection.

In regard to the treatment of the helminthiasis, I am precluded from entering into details here; nevertheless, I am glad to perceive that the principles which I long ago enunciated have received approval both at home and abroad. As stated in my ‘Lectures’ our object should be not to interfere with, but to promote nature’s curative efforts. If I read the pathological facts correctly, she seeks to bring about this result by erecting artificial barriers which serve to moderate the bleeding. In this way, under ordinary circumstances, the life of the bearer is sustained, or held in the balance until the parasites either perish or cease to be capable of causing active disease. Depend upon it, this is the principle which should guide physicians in their treatment of the Bilharzia disorder. If the adult parasite were merely attached to the lining membrane of the bladder, then powerful diuretics and medicated injections would probably prove serviceable; but since the entozoa reside in the blood we must be careful not to increase the patient’s troubles. In the case of intestinal worms the most powerful parasiticides may be prescribed without let or hindrance; but that drug must be a truly subtle worm-poison which, when taken into the system, shall kill the blood-flukes without exerting any injurious effects upon the parasite bearer.

When, in 1872, I published my lectures on helminthology, I remarked that it was not improbable that, ere long, many more cases of Bilharzia disease would be brought to light. What has been added in this respect is chiefly due to the researches of Sonsino, but a case of some interest has been recorded comparatively recently by Dr W. K. Hatch, stationed at Bombay. From the particulars furnished it seems evident that the victim, an English gentleman, contracted the disease by drinking water, either in Arabia or in Egypt, in which latter country, however, he had only sojourned fifteen days. From the patient’s statements it appears that, hæmaturia is frequent amongst the Arabs. Incidentally, Dr Hatch mentions that Dr Vandyke Carter had informed him that, so early as the year 1862, he (Dr Carter) had detected the embryos of Bilharzia in the urine of an African boy admitted to the Jamsetjee Jejeebhoy Hospital. The treatment employed by Dr Hatch was that recommended by Dr Harley in his well-known memoir. Having myself energetically opposed Dr Harley’s views on pathological grounds, I am not surprised to see it stated that Dr Harley’s method of treatment effected “no diminution in the number of the parasites.” As I said in my lectures (now out of print) it is evident that “nature” in view of moderating the hæmaturia--by the formation of plugs at the ulcerated points of the mucous surface--sets up the artificial barriers above referred to; therefore if you catheterise and employ medicated injections you do more harm than good. As to the administration of belladonna internally, in view of retarding development, or of destroying the parasite, no good can be expected from this source. I certainly obtained better results with buchu and bearberry (_Arctostaphylos_).

In the matter of sanitation it is quite evident, from the foregoing data, that the danger of infection cannot arise from the drinking of impure water, as ordinarily understood. The embryonal larvæ would be killed by an admixture of sewage. It is obvious that infection can only occur from swallowing free cercariæ or freshwater mollusks which contain the higher larval forms in their encysted or pupa condition. Slow running streams or stagnant pools with sedgy banks are eminently favorable to the existence and multiplication of intermediary bearers, and consequently their waters are dangerous if employed for drinking purposes.

BIBLIOGRAPHY (No. 12).--_Bilharz_, in Siebold and Köll., ‘Zeitsch. für wissensch. Zool.,’ iv, 1851.--_Idem_, ‘Wiener medic. Wochenschrift,’ 1856.--_Cobbold, T. S._, “On some new forms of Entozoa (_Bilharzia magna_),” ‘Linn. Trans.,’ vol. xxii, p. 364, 1859.--_Idem_, “Synopsis of the Distomidæ,” in ‘Proceed. Linn. Soc.,’ vol. v, Zool. Div., p. 31, 1860.--_Idem_, “Remarks on Dr J. Harley’s _Distoma capense_,” in ‘Lancet,’ also in the ‘Veterinarian,’ and in ‘Intell. Observer’ for Feb. and March, 1864.--_Idem_, “Entozoa,” l. c., p. 197, 1864.--_Idem_, “On Blood Worms,” Lecture xx in ‘Worms,’ l. c., p. 145 et seq., 1872; Tommasi’s edit., Vermi, p. 141, 1873.--_Idem_, “On the Embryos of _Bilharzia_,” ‘Brit. Assoc. Rep.,’ 1864.--_Idem_, “On the Development of _Bilharzia hæmatobia_, together with Remarks on the Ova of another Urinary Parasite occurring in a case of Hæmaturia from Natal,” ‘Brit. Med. Journ.,’ July, 1872; repr. in the ‘Veterinarian,’ 1872.--_Idem_, ‘New Entozootic Malady, &c.’ (brochure), London, 1865.--_Idem_, “Helminthes,” in Gunther’s ‘Record of Zool. Literature,’ p. 617, 1865.--_Idem_, “Entozoa in relation to Public Health and the Sewage Question,” Rep. of the Proceed. of the Metrop. Assoc. of Officers of Health, in ‘Med. Times and Gazette,’ Jan., 1871, repr. in the ‘Veterinarian,’ p. 359, 1871.--_Idem_, “Verification of recent Hæmatozoal Discoveries in Australia and Egypt,” ‘Brit. Med. Journ.,’ June, 1876.--_Idem_, “On Sewage and Parasites, especially in relation to the Dispersion and Vitality of the Germs of Entozoa,” rep. in ‘Med. Times and Gaz.’ for Feb., and the ‘Veterinarian’ for May, 1871.--_Davaine, C._, l. c., ‘Synops,’ and p. 312, 1860.--_Diesing, C. M._, ‘Revis. d. Myzelmith,’ Vienna, 1858.--_Griesinger_, “Klin. und Anat. Beobachtungen über die Krankheiten von Egypten,” in ‘Arch. für physiol. Heilkunde,’ 1856.--_Idem_, ‘Gesammelte Abhandlungen,’ Berlin, 1872.--_Idem_, ‘Arch. d. Heilk.,’ 1866.--_Harley, J._, ‘On the Hæmaturia of the Cape of Good Hope, produced by a Distoma,’ rep. in ‘Lancet,’ and ‘Med. Times and Gaz.,’ Feb., 1864; also in Ranking’s ‘Abstract,’ p. 173, 1864, and fully in ‘Medico-Chirurg. Trans.,’ 1865.--_Idem_, “On the Endemic Hæmaturia of the South Eastern Coast of Africa,” ‘Med.-Chir. Trans.,’ vol. liv, 1871.--_Idem_, in Hooper’s ‘Vade Mecum,’ 1869.--_Hatch, W. K._, “Case of _Bilharzia hæmatobia_,” in ‘British Medical Journal,’ Dec. 14, 1878, p. 875.--_Küchenmeister, F._, ‘Parasiten,’ 1855; Eng. edit., p. 277, 1857.--_Leuckart, R._, l. c., s. 617, 1863.--_Sonsino, P._, “Richerche intorno alla Bilharzia hæmatobia in relazione colla Ematuria Endemica dell’ Egitto e nota intorno un Nematoideo trovato nel Sangue Umano,” ‘Estr. dal Rend., del. R. Accad.,’ 1874.--_Idem_, ‘Della Bilharzia hæmatobia e delle alterazione Anatomo-patologiche che induce nell’ Organismo Umano, loro importanza come Fattori della Morbilità e Mortalità in Egitto, con cenno sopra una Larva d’Insetto Parassita dell’ Uomo. Estratto dall’ Imparziale,’ Firenze, 1876.--_Idem_, ‘Sugli ematozoi come contributo alla Fauna Entozooca Egiziana,’ Cairo, 1877.--_Idem_, “La Bilharzia hæmatobia, et son rôle Pathologique en Egypte,” ‘Arch. Gén. de Médicine,’ for June, p. 650, 1876.--_Idem_, “Intorno ad un nuovo Parassita del bue (_Bilharzia bovis_),” ‘Estr. dal Rend. del. R. Accad. di Napoli,’ 1876.--_Weinland, D. F._, l. c., p. 67, 1858.

SECTION II.--CESTODA (Tapeworms).

_Tænia mediocanellata_, Küchenmeister.--This cestode is frequently spoken of as the unarmed or beef tapeworm. In general appearance it is very similar to the armed form. It is, however, a larger and broader animal, being at the same time rather stouter. It varies usually from fifteen to twenty-three feet in length, but specimens have been described as attaining thirty feet. It is called the unarmed tapeworm in consequence of the absence of any coronet of hooks on the head; and consequently, also, from there being no prominent rostellum or proboscis. The place of the last-named structure, however, is supplied by a small rudimentary disk, which I have seen protruded on pressure (fig. 20). Usually this disk forms a more or less conspicuous cup-shaped circular depression, which has been compared to and described as a fifth sucker. That it is not, in any structural sense, comparable to the true suckers, I have had abundant opportunity of ascertaining; nevertheless, I do not doubt that it is to a slight extent capable of being used by the parasite as a supernumerary holdfast. The anchorage thus secured, however, is by no means equal to that obtained by the armed species. This explains the comparative difficulty we find in procuring a specimen of the armed tapeworm with the head attached.

The establishment of this species as distinct from _T. solium_ is due to Küchenmeister; but it is curious to observe how accurately this determination was foreshadowed by the shrewd naturalist and theologian, J. A. E. Goeze, who clearly indicated two forms of the common tapeworm, remarking (l. c., Bibl. No. 1, s. 278):--“Die erste ist die bekannte grosse, mit langen dicken und gemästeten Gliedern, die ich _Tænia cucurbitina, grandis, saginata_, nennen will.” The same author (s. 245) pointed out the resemblance subsisting between the tapeworm of the cat (_T. crassicollis_) and the vesicles (“Krystallblasen”) and their contained “erbsförmige Blasen” (_Cysticercus fasciolaris_) of the mouse. Thus the celebrated pastor of St Blasius, in Quedlinberg, almost contemporaneously with Pallas, early arrived at the conclusion that the hydatid-measle was a kind of tapeworm.

Respecting the organisation of this worm I may observe that the mature joints have a more complicated uterine organ than obtains in _Tænia solium_, presenting nearly double the number of lateral branches. They are more closely packed, running outwardly in an almost parallel manner. The first sexually mature proglottis occurs at about the 450th joint, but whereas, in the pork tapeworm, only some 200 subsequent segments share this perfect character in the beef tapeworm, according to Leuckart, as many as 360 or even 400 mature joint may be present. The joints are very liable to form monstrosities; these abnormalities sometimes affecting the reproductive organs, which become doubled or even trebled. In the Hunterian collection there is a proglottid showing twenty-two sexual orifices. Dr Cullingworth, of Manchester, has described a specimen in which the joints are curiously tripartite.

As already hinted the true source of this parasite has been proved by experiment; the first successful worm-feeding having been accomplished by Leuckart. Mosler’s, and subsequently my own feeding experiments, immediately followed. Other successful experiments with this species have been conducted by Zurn, Probstmayer, St Cyr, Perroncito, Masse and Pourquier, and Zenker. As will be again mentioned below Dr Oliver, R.A., whilst stationed at Jullundur, successfully reared the adult tapeworm in a Mohammedan groom and in a Hindoo boy. It will also be seen that Prof. Perroncito reared the worm in a student in fifty-four days. In my own experiments on animals I was assisted by Professor Simonds. The feeding materials were tapeworms expelled from my own patients. We obtained the following interesting results:

_Exp. 1._--A calf. First feeding, Dec. 21st, 1864. Marked symptoms. Slaughtered April 3rd, 1865. Result positive.

_Exp. 2._--A calf. First feeding, April 13th, 1865. Second, third, and fourth feedings in May and June. No symptoms. Died on Sept. 3rd, 1865, after thirty-six hours’ illness with “cattle plague.” Result stated to have been negative as far as the muscles were concerned. Viscera not examined.

_Exp. 3._--A Dutch heifer. First feeding, March 3rd, 1865. Three subsequent feedings. Symptoms only slight. Slaughtered April 4th, 1866. Result positive. Measles especially numerous in the diaphragm, but all had undergone calcareous degeneration.

_Exp. 4._--A calf. Fed May 27th, 1872, with ripe proglottides. Marked symptoms set in on June 7th, which began to abate on the 12th, and had nearly disappeared by the 20th of the same month. The record of the post-mortem result has been lost; but the animal was infected.

_Exp. 5._--A calf, which had been made the subject of a “glanders experiment.” First fed on Oct. 17th, 1872, and thrice in the following year, Jan. 1st and 11th, and March 8th. No symptoms having appeared the animal was kept for six or eight months after the last feeding. Seeming to be free from disease of any kind, it was sold as a sound heifer.

_Exp. 6._--A young heifer calf, of six months. Fed Oct. 18th, 1873, with the mature proglottides of a large beef tapeworm. No symptoms. Slaughtered several months afterwards. Result stated to have been negative. Unfortunately I was not present at the autopsy.

_Exp. 7._--A young heifer. First fed May 19th, 1874, with the joints of a tapeworm, and again on June 12th. No apparent ill effects resulted, but the animal died in October. At the post-mortem examination, made by Prof. Simonds, no parasites were observed. Subsequently I found calcareous specks in the liver which proved to be degenerated measles.

_Exp. 8._--A calf. Fed on or about March 24th, 1875, with sexually mature joints. The calf was put to and remained with a foster mother until it died from disease of the larynx on the 15th of the following July. The animal was ill-treated by its foster parent, and at the post-mortem I observed a large intercostal cicatrix, evidently the result of injury. In this case I devoted several hours to the exploration of the muscles and viscera. Not a trace of the _Cysticercus bovis_ could be found in the muscles or connective tissues, but the liver contained scores of perfectly developed measles, besides hundreds of others in various stages of calcareous degeneration. On comparing some of the latter with those I had obtained from the preceding experiment the pathological appearances were at once seen to be identical. It was easy to find and pick out the measles in their cysts from the naturally friable liver. I also detected four Cysticerci in the lungs, two of which had degenerated. Microscopic examination confirmed my interpretation of the naked-eye appearances.

Fragmentary as the above data are, they serve to show that we have hitherto been too hasty in concluding that beef and veal measles reside only in the voluntary and striated muscles of their hosts. The facts here recorded prove that the liver of a calf may be extensively invaded by cysticerci, and yet the animal will exhibit no sign of constitutional disturbance. The cestode tuberculosis may come and go without any diagnostic symptom, whilst a few months suffice for the natural death and decay of the parasite by calcareous degeneration. Thus it becomes extremely probable that many experiments hitherto regarded as negative in their results have really been positive; the pathological evidences having been either misinterpreted or altogether overlooked. Every pathologist is familiar with gritty particles in the various viscera of man and animals, but few are probably aware how constantly these are dead and degenerated Cysticerci. The gritty particle itself may be reduced to the merest point, no larger than the _receptaculum capitis_ of the Cysticercus itself, and in course of time it will disappear entirely. Practically it is satisfactory to have experimental evidence of the fact that cattle, as well as other animals, however extensively measled they may have been, can become thoroughly cleansed of the disorder by nature herself. It is only necessary that the diseased animals be separated from infectious influences.

Although the beef measle has never yet been found in man, I have for convenience sake introduced the facts of larval parasitism in this place. The sanitary bearings of this subject are far too important to be dismissed in a summary manner. I have shown that the prevalence or rarity of the beef tapeworm in man is strictly dependent upon the habits of the people; this same cause operating to produce healthy or diseased meat-food, according to the degree of civilisation. In this connection the oft-quoted statements of Kaschin respecting the prevalence of tapeworms among the Burätes, and the well-known frequency of this entozoon in Abyssinia, need only be alluded to.

When discussing the food question in my ‘Manual,’ I freely availed myself of facts privately communicated by Dr. Joseph Fleming, and I especially referred to the published labours of Lewis, Hewlett, Veale, and other observers stationed in India. Beef measles are extremely common in the cattle of the north-west provinces of India, so much so that severe restrictions have been imposed upon the consumption of ration beef. The presence of a few measles in the flesh of cattle has been deemed a sufficient excuse for condemning and burying entire carcases. The measle is easily distinguished from that of mutton and pork by the fact that its head is not furnished with hooks, whilst in the place of a rostellum there is a small, centrally placed, retractile disk, which assumes the appearance of a supplementary sucker as in the adult worm. The four true suckers are also comparatively large. The measle usually varies in size from the fourth to the half of an inch in length, but my cabinet contains a specimen nearly an inch long. This was contributed by Dr J. Fleming, who mentions having seen a measle which, when unrolled, measured nearly an inch and a half in length. Although thousands of these bladder worms must exist in the cattle of England, up to the present time not a single instance has been recorded of the occurrence of these cystic parasites in the United Kingdom, except in our experimental animals. Notwithstanding my inquiries, I have not yet found a butcher, flesher, meat-inspector, or veterinarian, who has encountered this parasite in any animal slaughtered for the market. Several butchers have denied their occurrence in meat sold by themselves. Even so late as June, 1874, the presence of measles in the flesh of cattle was denied before an assembly of French _savans_; yet for many years past I have constantly exhibited measly beef and veal in the lecture room of the Royal Veterinary College. (See the discussion of the Société de Thérapeutique, recorded in the ‘Bullétin Gén. de Thér.’ for June 30th, 1874, and also the ‘Jour. de Thér.,’ No. 14, for July, p. 556, where, however, special remarks on this head have been omitted; see also the ‘Lond. Med. Record’ for July 29th, 1874, p. 472, and the ‘Lancet’ for Dec., 1874, p. 794.) Quite in contrast with the statements referred to are those of recent Italian observers.

Some few years back Professor G. Pellizzari communicated to the Medico-Physical Academy, at Florence, the results of a series of experiments conducted by himself, with the assistance of Dr Tommasi, in regard to the temperature necessary for the destruction of cysticerci in measled meat. An account of these experiments is published in Tommasi’s edition of my ‘Manual.’ The researches were made in relation to certain sanitary measures effected by the Municipal Commission of Florence, the express object of these measures being to prevent the injurious distribution of measly meat, especially that of swine. Signor Bosi, the superintendent of the public slaughterhouses, granted every facility in his power. In a previously published memoir by Professor E. Perroncito it was stated that measly meat (_panicatura degli animali_) required a higher temperature than that of boiling point for the destruction of the bladder worms in question. In this opinion Signor Bosi shared. According to the original memoir of Perroncito we are told that “about twenty specimens of Cysticerci were collected by the author, and placed in boiling water. After twenty minutes’ boiling, not one of the parasites appeared to suffer. The head continued to be drawn into the body, and when the Cysticerci had their heads drawn out one by one they still appeared to possess all the elasticity of living bladder worms, displaying those movements of extension which are proper to parasites not yet dead. The hooks were observed regularly disposed on the proboscis, where they formed a double crown, the suckers remaining intact.” Perroncito remarked, however, that the Cysticerci showed a coloring tendency towards brown, and he added that “with the aid of two needles it became easy to lacerate the body of the Cysticercus, which appeared to be swollen, and possessed of diminished cohesion of its parts.” It was evident to all eyes, observed Professor Pellizzari, that these statements involved clear contradictions. Yet again, at page 28 of the memoir, Professor Perroncito wrote:--“During the past winter I introduced some little slices (_fettuccie_) of muscle-flesh (8 to 10 millimètres in thickness), infested with Cysticerci into a vessel (_cassolina_) containing fat at the temperature of 190 to 200° Cent. (374 to 400° Fahr.). At the expiration of ten or fifteen minutes the slices of meat were fried, and the Cysticerci lying at the surface had acquired a light brownish colour, as if they were roasted. By breaking up the slices one could still see the small reddish muscular bundles, whilst the Cysticerci in the middle remained entire and well preserved. Their heads displayed the hooks and suckers regularly distributed.” It is certainly singular, as Pellizzari observes, that these Cysticerci, having been thoroughly fried and roasted, should still remain alive and in their normal state; but the ultimate conclusion at which Perroncito arrived was still more startling, and one which, if it were true, would not fail to create a considerable stir among our officers of health. On reviewing the whole matter Perroncito says:--“It appears to me that the melted fat alone of hogs (_maiali grandinosi_) should be utilised, and I am pleased to reckon the illustrious Gerlach and all other distinguished practitioners to be of the same opinion. Permit me, therefore, being well satisfied also with the results of many other experiments, once more to advance the conclusion that, if it is not certain that the Cysticerci die at from 80 to 100° Centigrade (176 to 212° Fahr.), we are quite sure that they dry up and become completely mummified at 125, 130, and 150° Cent. (257, 268, and 302° Fahr.), temperatures which we could easily produce by means of a properly constructed apparatus.”

After remarking upon the serious nature of the conclusion which Perroncito sought to establish, Professor Pellizzari makes further use of quotations which bear upon the question as to whether the quality of the vessels in which the fat of diseased hogs is melted down may not largely affect the degree of high temperature sought to be obtained (in view of a perfect destruction of the Cysticerci). Perroncito repeatedly witnessed the operations of pork-butchers; and when portions of meat were introduced, with water, into the cauldrons, he always saw that the temperature “was maintained between 97° and 98° Centigrade.” However, this part of the question may be dismissed in a very few words, since Perroncito himself finally allows that “the different composition of the vessels cannot elevate the temperature of the fat by many degrees.”

With the praiseworthy intention of either verifying or refuting these conclusions, Pellizzari, with the approval of Bosi and with the assistance of Tommasi, instituted a fresh series of experiments at a private laboratory. The details of these experiments are exceedingly interesting; but as their record occupies several pages of Tommasi’s appendix already referred to, I must content myself with a general statement of the results obtained. Professor Pellizzari found that Cysticerci, so far from requiring a temperature of upwards of 100° Centigrade for their destruction, die at a temperature of 60° Centigrade (140° Fahr.). He had, it appears, previously taken the initiative in recommending certain measures to the Florentine municipality, in view of protecting the public health, and he had now the satisfaction of more than confirming the wisdom of these sanitary precautions. In excessively measled animals the fat is removed and boiled in suitable cauldrons, and has potash mixed with it to render it useful for industrial purposes. By the various measures adopted the entire animal is utilised, and with proper precaution there seems little chance for the measles to arrive at the tænioid or sexually mature condition.

In the next part of his communication Pellizzari touches upon the question of measles in beef, referring especially to the experimental labours of Leuckart and myself. Finding additional support from our views Pellizzari declared the propositions of Dr Perroncito as of no value whatever. “But how is it,” he adds, “that notwithstanding that so low a temperature suffices to kill these cysticerci, yet cases of Tænia are continually occurring?” The answer to this question will appear in the sequel; but meanwhile it will be as well to refer to the recent _brochure_ by Dr Giacomini. This author appears to have had no opportunity of perusing Pellizzari’s communication already cited, and consequently it is not surprising that he should, in common with others, have accepted the original conclusions of Perroncito. Dr Giacomini clearly perceives that, whatever precautions of a hygienic character are suitable for the prevention of disease arising out of the consumption of measly pork, the same, or at all events similar, measures ought to be adopted with the view of checking tapeworm affections arising from the ingestion of other kinds of meat, especially veal and beef. Like Pellizzari, he is satisfied as to the human origin of the small bladder worms found in cattle, and establishes this position not only from the oft-quoted experiments of Leuckart and Mosler, but also from those conducted by myself and Simonds in England, and by Professor F. Saint-Cyr in France. From a careful review and consideration of all the facts of the case, he recommended a more complete supervision over the flesh of oxen before it is employed commercially, and greater precaution when employing veal as food, by causing it to be subjected to a high temperature, in order that the parasites may be killed before it is ingested. It is evident that Giacomini thinks that a temperature exceeding that of boiling-point is necessary for the destruction of the beef and veal measles, since he immediately adds, “Though experiments have not been made with the object of ascertaining the amount of resistance of heat which the unarmed cysticercus can bear, yet, judging by those conducted by Professor Perroncito on the measle of the hog, we are in a position to say that a temperature of 135° Cent. (275° Fahr.) is necessary for the destruction of an isolated Cysticercus, whilst the heat should be raised from 150° to 200° Cent. (302° to 392° Fahr.) for ten or fifteen minutes, in order to ensure the complete destruction of the Cysticerci encapsuled in the interior of a piece of meat.” I have abridged this portion of Giacomini’s text, because his statements are pretty much the same as those already quoted from Perroncito (as cited by Tommasi). But, in the next place, Dr Giacomini is in error when he states that experiments had not been performed on the Cysticerci of the ox. So far from this being the case, similar experiments had long previously been conducted by Dr Lewis in India; and these researches had quite as much to do with the measles or Cysticerci of beef as they had with those of the hog, if not more. Naturally but few foreign investigators can have had access to the work in which Lewis’s experiments were originally recorded, and to which, therefore, I must call their attention. Thus, Dr Tommasi has fallen into the error of supposing that the investigations of Lewis were made in England. It is of very little moment where the experiments were carried on, but Tommasi’s statement (appendix, loc. cit., p. 161), wherein he says that Pellizzari’s experiments, in which he himself took part (_ai quali io stesso ho assistito_), are even more complete than those made in England by Dr Lewis, and in Germany by Dr Küchenmeister, cannot be allowed to pass unchallenged. If Tommasi had enjoyed the opportunity of consulting Lewis’s original memoir, he would not have underestimated our countryman’s labors. The memoir by Lewis is singularly complete, and well-nigh exhausts all the facts that can have any interest in relation to the question of public health. Towards the close of his essay he expressly states, as the result of investigation--“(1) That exposure to a temperature of 120° Fahr. for five minutes will not destroy life in Cysticerci, but that they may continue to manifest indications of life for at least two or three days after such exposure; (2) that exposure to a temperature of 125° Fahr. for five minutes does not kill them; but (3) after being subjected to a temperature of 130° Fahr. for five minutes, they may be considered to have perished. After exposure to this and higher temperatures, in no instance have I been able (he adds) to satisfy myself that the slightest movements took place in their substance when examined even under a high power. At least, it may be confidently asserted that, after exposure for five minutes to a temperature of 135° to 140° Fahr., life in these parasites may be considered as absolutely extinct” (p. 139). Thus the statements of Lewis and Pellizzari were in perfect accord; and seeing that their conclusions were alike the result of very careful and independent inquiry, it seemed as if the question at issue was finally solved. These investigations made it perfectly clear that Cysticerci of all kinds, whether found in veal, beef, or pork, could not retain their vitality when exposed to a temperature of 60° Centigrade, or, in other words, 140° Fahr.

The rather severe strictures made on Perroncito’s earlier experiments induced the Turin professor to go over the subject more carefully, when he obtained excellent results. He finally ascertained that Cysticerci perished at a temperature below 50° C. (122° Fahr.). In May, 1877, Dr Perroncito furnished me with an account of his researches. With the exception of a few verbal alterations, for which I am responsible, Perroncito wrote as follows:

“In order to resolve the highly important question of the tenacity of life of the Helminths and corresponding larval forms, I made since 1871 a very long series of experiments on the _Cysticercus cellulosæ_, which were published almost at the same time with others of the same kind, made by Dr Lewis in Calcutta. Towards the end of 1874 Mr Pellizzari, of Florence, disputed the results of the investigations which I had made known two years before, _i.e._ in 1872, and agreed with Dr Lewis, who had stated already that the _Cysticercus_ exposed to a temperature of 55° C. can be held for dead after five minutes, and also with Dr Cobbold, who thought the temperature of 60° C. quite enough to kill it. But the characters he (Mr Pellizzari) relied upon, needing the exactness and precision required to enlighten and persuade in the most important scientific questions, gave rise to a mistrust in the most scrupulous amongst the men devoted to biological pursuits and to several hygienic measures on the part of the sanitary inspectors with regard to infected pork. Therefore, my conclusions, argued from the experiments made in 1871-72, were still those followed by the most important Italian cities, and approved in principle by the superior Board of Health in 1873. I expressed doubt then about the _Cysticercus_ dying at a temperature lower than 100° C., and some person misconstrued these doubts, saying that I had contradicted myself in my work. However, as I could not assert they died at 80°--100° C., I only noticed the alteration of color and cohesion which happened in the _Cysticercus_ exposed to various degrees of temperature, to the end that I might contribute usefully to the solution of the difficult question, and concluded that ‘if we could not be sure of the _Cysticercus_ dying at 80°-100° C., it was certain at all events that they perished at 125° or 130° C.’ Not wishing to prejudice the question, I never said that they did not die at 80°--100° C., but simply stated that at this temperature we could not be certain of their death.

“Now, after a large number of experiments, I have been able to ascertain with exactness the lowest degree of temperature required to kill infallibly the _Cysticercus_ and other parasites of animals. The means I made use of for this kind of investigation were Mr Schulze’s heating table, the neutral tincture of carmine, the tincture of hæmatoxylon, and breeding experiments.

“My method is founded essentially--

“(_a_) On the fact that the _Cysticercus_ when it is fresh and is stretched and conveniently prepared in pure water, or in chloride of soda very much diluted, and afterwards brought gradually from the temperature of the ambient air to that of the body of higher animals and to degrees of heat still more elevated, until life is extinct, keeps moving to and fro with more or less energy throughout its body, using especially its suckers and proboscis.

“(_b_) On the greater imbibing power of the dead tissue generally, which is undoubtedly far more apparent in insects and plathelminths.

“(_c_) On the experiments made to ascertain the value of the two above-stated facts.

“If, after having prepared a _Cysticercus_, newly extracted from a pig in the way we have pointed out, we examine it with a microscope on M. Schulze’s heating table, we find that usually it begins to move after 30° or 35° C., and each moment with greater activity, especially after 38°, 40°, 42°, 44°, 45° C. The temperature being raised progressively, we see that the _Cysticercus cellulosæ_ puts a stop to its movements occasionally at 45-46° C., seldom at 47° C., more frequently at 48° C., sometimes at 49° C.; and, in fifty and more experiments, only one _Cysticercus_ was able to live on beyond 49° C., standing still at 50° C.

“As soon as it stands still the parasite is dead. In fact, if we lower again the temperature gradually to that of the ambient air, and if afterwards we raise it a second time, we pass through all the intermediate temperatures without the Cysticercus showing the least signs of life.

“But a more convincing proof of the death of the parasite is got from the greater imbibing power of the tissue when life is extinct, the same over the whole body of the plathelminths, and their larval forms. If we dip the _Cysticercus_ alive with its head stretched in the neutral tincture of carmine or hæmatoxylon we can leave it there even two, four, eight, ten, or twelve hours and more, without the head coloring or a real imbibition taking place; this begins only after the _Cysticercus_ is dead, so that if the _Cysticercus_ is brought first to a temperature hot enough to kill it (with M. Schulze’s tables to one of 48°, 49°, 50° C.) and dipped afterwards in the above-mentioned tinctures, it colors intensely in less than 45°, beginning from the head, and onwards to the extremity of the cyst of the tail. The head colors more intensely and rapidly than the neck, as it is covered with very numerous calcareous corpuscles, which are not met with so frequently in the remaining part of the body.

“_Cysticercus cellulosæ_ of the pig, and that of the _Tænia mediocanellata_ of the calf, brought gradually to a final temperature, the first of 50° C., and the second of 44°, 45°, and 47° C., and then swallowed alone, or with a piece of butter or crumb of bread, never produced the _Tænia_ in the valiant students who voluntarily undertook to make the experiment of swallowing them.

“My investigations were extended to other kinds and forms of Helminths, and the results were always the same, so that, abiding by the same principles, I was able to ascertain that--

“1st. The _Cysticercus cellulosæ_ of the pig dies sometimes at 45° C., more frequently at 47° C., ordinarily at 48° C., very seldom reaches alive 49° C., and is quite an exception when it resists for a few moments the temperature of 50° C., so that we can say that the _Cysticercus_ brought gradually up to this temperature most assuredly dies if it is kept there longer than one minute.

“2nd. A _Cysticercus cellulosæ_, extracted by Professor Raymond from the conjunctiva of a child’s eye, died between 45° and 46° C.

“3rd. The _Cysticercus_ of the _Tænia mediocanellata_ dies sometimes at 44° C., very often at 45° C., and does not resist a temperature superior to 46° C.

“4th. The _Cysticercus pisiformis_ of the rabbit, like the _cellulosæ_, dies sometimes at 45° and 46° C., but generally stands still and perishes at 47° and 48° C.

“5th. A _Cysticercus tenuicollis_ died at 49° C.

“6th. The _scolici_ of the _Cœnurus cerebralis_ of a sheep died at 42° C.

“7th. The _scolices_ of the cysts of _Echinococcus polymorphus_ die generally between 47° and 48° C., and in no case amongst those I have experimented on did it reach 50° C. alive.

“8th. The _Tænia cucumerina_ died, one at 43° C., and a second parasite at 45° C.

“9th. A few individuals of _Tænia serrata_ of the dog died at 50° C.

“10th. Two individuals of _Tænia perfoliata_ of the horse died, the first at 45° C., the second at 50° C.

“11th. The embryos of the _Filaria microstoma_ of the horse began to stand still at 46-47°, and all died at 48° C.

“12th. The embryos of the _Filaria megastoma_ of the horse’s stomach died at 47° C.

“13th. The _Trichina spiralis_, both free and in a cyst, in several experiments always died at 48° C.

“14th. The embryos of the _Strongylus filaria_ of the sheep stood still at 50° C.

“15th. Probstmayer’s viviparous oxyurids, the infusoria of the colon and cæcum of the solipeds, and the psorosperms of the liver of the rabbit did not stir at all.

“Each experiment lasted about ten minutes, and the temperature rose from 8-10° C. to 45-46° C. in six to eight minutes; and from 46° to 50° in one minute. These experiments have a great value, both scientific and practical, as they show, on one side, which is the lowest intensity of heat sufficient to kill always the _Cysticercus_, the _Trichina_, and other parasites, reducing thus by far the tenacity of life generally attributed to a large number of Helminths and corresponding larval forms. They assure us, moreover, of the harmlessness of the flesh infected by the above-mentioned parasites, when it is cooked in such a manner as to reach the temperature of 50° C. over all points of the pieces, even though it be kept at such a degree of heat not longer than five minutes.

“In a piece of leg of pork the _Cysticerci_ were found alive in all places not yet putrefied twenty-nine days after the animal had been slaughtered. On the other hand, in the dry muscles of a calf the _Cysticerci_ of the _Tænia mediocanellata_ were all found dead fourteen days after the slaughtering of the animal. I have ascertained that putrefaction of the flesh is fatal for the two larval forms of these different kinds of helminths.”

In a subsequent communication received from Professor Perroncito towards the close of the year 1877 he writes:

“At the last meeting, held on April 23rd, I made a statement to the Medical and Surgical Society of Turin, of the results of other experiments tried by heating at M. Schulze’s table and by the imbibitions with the neutral tincture of carmine, through which I came to the conclusion that the _Cysticerci_ of the _Tænia mediocanellata_ die sometimes at 44° C., now and then at 45° C., and always at 46° C. I therefore concluded that they could in no case survive at 47° C. and 48° C. when they were maintained at this temperature at least five minutes. But to the end of more fully corroborating the facts I had thus communicated, I, contemporaneously with these, made some breeding experiments with the same _Cysticerci_ on bold and courageous students who generously offered themselves for the benefit of science.

“Consequently I am now enabled to state that neither Mr Gemelli nor Dr Ragni contracted the _Tænia_, though each of them had eaten a _Cysticercus_ of the _Tænia mediocanellata_ previously, and respectively subjected to a temperature of 45° C. and 47° C. The larvæ were properly prepared and submitted to gradual heating on the above-mentioned table, and swallowed when they no longer gave signs of life. In like manner no generation of the _Tænia_ took place in the body of Mr Martini, who ate the _Cysticercus_ brought to a temperature of 44° C. It was maintained at this degree of heat during a period of about three minutes, and swallowed whilst a very slight movement was still visible in a portion of its neck.

“In another student, on the contrary, who ate a living _Cysticercus_ of the _Tænia mediocanellata_, the tapeworm reached its maturation in fifty-four days and eliminated the two first proglottides. It threw off two more on the fifty-eighth day, and thirty on the sixtieth. Sixty-seven days after swallowing the _Cysticercus_ this courageous young man, having, like his three companions, taken some kousso and castor oil, emitted the strobila. It was furnished with 866 rings, but destitute of the neck and head. Its measurement afforded a total length of 4·274 mètres.

“Adding now to the 866 proglottides the thirty-four already eliminated, 900 would be the number of the segments; and reckoning the length of each of the latter to be fourteen millimètres, we should have had the _strobila_ (deprived of the head and neck) reaching a length of 4·75 mètres. Further, calculating the head and neck to be eight millimètres long, a total length of 4·83 mètres would be the result.

“From all these facts we may conclude that the _Tænia_ has, in our instance, reached an approximative length of seventy-two millimètres a day, affording a daily production of 13·43 proglottides.”

In relation to requirements of state medicine I have thought Perroncito’s researches sufficiently valuable to be quoted at some length; but their chief interest culminates in the worm-feeding experiments. Excellent in all respects as was the conduct of the medical students who, with Professor Perroncito’s approval, swallowed living specimens of the _Cysticercus bovis_, the intentional ingestion of beef measles is by no means a novelty. Eight or ten years back Dr Oliver (after explaining to one of the selected victims the possible consequences of the experiment) induced a Mahommedan syce or groom and a Hindoo boy to swallow perfectly fresh and living beef measles. In this way Dr Oliver successfully reared the _Tænia mediocanellata_ in India, and he was thus enabled to fix the amount of time necessary for the full growth of the strobila. Many other persons have displayed an equal amount of zeal in the cause of helminthology, by partaking of the larvæ or germs of other parasites. Thus, at the risk of repetition, I may state that Möller many years ago swallowed the slender-necked hydatid (_Cysticercus tenuicollis_) in the hope of infesting himself with _Tænia marginata_. Several persons have defiantly swallowed trichinised flesh. Professor Leuckart and some of his pupils also courageously swallowed the eggs of _Oxyurides_, and they had the infinite satisfaction of noticing the young worms in their fæcal discharges some fifteen days afterwards. Dr Crisp ate part of the cooked flesh of an animal that had died of cattle plague, and I myself partook of moderately cooked meat which I knew to be swarming with psorosperms. These obscure organisms were by some persons considered to be either a cause or product of the rinderpest. They will be noticed in my account of the Protozoal parasites.

For the purpose of advancing science and the welfare of the people, there are scores of persons always to be found ready to make personal sacrifices of the kind undertaken by Drs Ragni, Martini, and Gemelli. Unfortunately for English science there are not wanting people in this country who are prepared to threaten with fines and imprisonment any _savant_ who may think it desirable to perform a similar set of feeding experiments on animals. Invaluable for good as our experimental investigations have already been, it would seem as if it were the deliberate aim of these sentimental obstructives to put a stop to the acquisition of all useful knowledge in the future.

In reference to the rate of growth of tapeworms, Professor Perroncito’s determinations are useful, inasmuch as they verify certain ascertained facts with precision and confirm the general conclusion that had been drawn by practical helminthologists from various sources of information. In regard to the number of proglottides proper to a sexually mature tapeworm, the circumstance that Perroncito’s calculation was made without the head and a portion of the neck of the worm being present shows that it cannot be relied on absolutely; nevertheless, as far as it goes, it tends to confirm what Leuckart had long previously stated. I have possessed myself of upwards of thirty perfect beef tapeworms expelled from my patients, and in some of the specimens it was noticed that the segmentation-rings in the region of the neck were far more crowded together than they were in others. I also possess a perfect _Tænia mediocanellata_, removed post mortem. Though the rate of growth may be the same from day to day, yet experience has shown that the number of proglottides actually cast off varies exceedingly. Küchenmeister’s estimate of the average number agrees in the main with what we have ourselves observed (five to twenty daily); and here again Perroncito’s investigations serve to verify the general correctness of our previous determinations.

To return to Pellizzari’s researches, one of the most important questions is that which relates to the prevalence of tapeworm. In this connection he first brings forward some very interesting and instructive data that had been previously communicated to the Medico-Physical Academy of Florence by Professor Marchi. On the occasion referred to Marchi had stated that, out of thirty-five Tæniæ which he had examined, only one belonged to the species known as _Tænia solium_; all the other thirty-four being of the unarmed type, or _Tænia mediocanellata_. Reflecting on this striking fact, and also on the circumstance that he had in vain begged his colleagues to send him specimens of _Tænia solium_, Marchi seems to have missed the very palpable explanation of this otherwise strange phenomenon. “How does it happen,” exclaimed Marchi, “that, notwithstanding the occurrence of 13,000 kilogrammes of the flesh of measled hogs in the public butcheries, I have seen but one specimen of _Tænia solium_, whilst thirty-four cannot have originated from the pig?” “The wherefore is obvious enough,” replies Pellizzari, “because our hygienic regulations demand that the flesh of the hogs be raised to a temperature of 60° Cent. (140° Fahr.);” and he then himself immediately proceeds to ask another question, namely, as to how it happens that the _Tænia solium_ is so frequently seen in other places. To his own question Pellizzari responds by remarking--(1) that there are not so many precautions (of a sanitary kind) taken in other places; and (2) that the people elsewhere consume more slightly salted or uncooked meat, as sausages and so forth (_come salame giovane, salciccia e via dicendo_). Pellizzari, having explained that Marchi’s thirty-four tapeworms must all have arisen from the consumption of the Cysticercus of the ox, then goes on to speak of the prevalence of tapeworm in Florence, even in little children. This last-named feature, he says, is due to the circumstance that raw meat is frequently employed as a restorative (_come cura ricostituente_). “Thirty years ago,” remarks Professor Pellizzari, “it was just as difficult to find a single _Tænia mediocanellata_ as it is now easy to find a great number of these worms; and all because it is nowadays customary to eat the flesh of the ox either insufficiently cooked or raw. This absolute inversion of the facts of the case affords proof of the correctness of the position sustained by me, to the effect that the cooking of meat up to the degree of temperature necessary for ebullition ensures the destruction of the Cysticerci.” Notwithstanding this statement of his own, Pellizzari thinks that the interference of inspectors may be pushed too far, and thus serve to bring about the very disasters which it should be their supreme object to prevent. Thus, he argues against the suggestions of those who would entirely prevent the sale of measly meat, and who would only permit, as obtains in the province of Modena, the melting down of the fat of hogs. Very strict measures of this sort would, as he says, constitute a radical means of entirely stamping out _Tænia_, but he also very judiciously reminds the sanitarian (_igienista_) that “such a step would be a serious thing for the tradesman, bringing injury not only to the municipal administration, but also proving an encouragement to smuggling. In this way the public health would sustain worse injury by the inducement held out to the owners of infected animals to slaughter them in secret butcheries, thus little by little withdrawing the meat from the superintendence of the public officials. By the adoption of fraudulent measures there would be a daily consumption of diseased meat; and thus also, while the public administration would suffer loss, the public health, on the other hand, would gain nothing.” In effect Pellizzari says, if we advise the employment of more severe and radical measures than those already in vogue in Florence, we should overburden the tradesman, almost compel him to defraud the exchequer by smuggling, and greatly injure the public health.

The facts and explanations advanced by Italian writers regarding the causes of the endemic prevalence of tapeworm, are in perfect harmony with those previously obtained from other sources. Respecting these causes there is much that is both new and interesting. The eighth annual report of the sanitary commissioner of the Government of India had already made us acquainted with the fact that during the year 1869, out of 13,818 head of cattle slaughtered in the stations of the Upper Punjab, 768 beasts were found to be infected with measle-cysts. This, as I have remarked (Tommasi’s edit., p. 54), “affords a rate of 5·55 per cent., being a considerable diminution of the proportion observed in 1868, when the percentage gave a total of 6·12. The reduction was, without doubt, due to the vigilance and enlightenment of the army meat inspectors. The prevalence, however, of tapeworm does not bear relation to the number of animals infested with Cysticerci so much as to the actual number of Cysticerci developed in infected animals. I have frequently pointed out the inadvisability of condemning and burying the carcases of measly oxen, whether there be few or many Cysticerci present, and I have stated, on trustworthy evidence, that even the presence of a few Cysticerci is deemed by some inspectors a sufficient reason for rejecting the entire animal. Such a waste should never be allowed. In regard to the numbers of ox-measles present in particular instances, I have elsewhere adduced some remarkable facts communicated to me by Dr Joseph Fleming, of the Indian Army Medical Staff. None of my experimental animals, though fed with scores of ripe proglottides, yielded such an abundance of Cysticerci as Dr Fleming encountered in Punjab cattle. In one pound weight of the psoas muscles Fleming counted no less than 300 Cysticerci.” From this it follows that the flesh of a largely infested animal is capable, under the circumstances of ration distribution and imperfect cooking, of originating numerous tapeworms.

Not many years back the leading medical journal of this country challenged me to produce evidence as to the injuriousness of beef and mutton from Cysticerci. The writer stated in his article that I had “failed to produce a single specimen of beef or mutton measles” which had not resulted from experiments conducted “at the Royal Veterinary College;” and he said, further, “that butchers, fleshers, and veterinarians were practically right in refusing to adopt the opinion of Dr Cobbold, that measled beef or mutton is produced to any great extent” independently. How palpably I endured a species of unjust reproach for being somewhat in advance of the knowledge current at the time may be gathered from the voluminous evidence which has since cropped up from various parts of the world. It was, indeed, mainly through experiments conducted at the Royal Veterinary College, and reported in the ‘Lancet,’ that professional men in India first became acquainted with the possibility of finding Cysticerci in beef.

The statements of Dr Joseph Fleming, who was one of the foremost in discovering cystic disease in cattle, have since received abundant confirmation. The Indian Government Reports given in the February issue of the ‘Madras Monthly Journal of Medical Science’ for 1873 are especially instructive. Referring to the prevalence of Cysticercus in the ration beef at Jullundur, in the Punjab, the Inspector General (India Medical Department) reports as follows:

“Cysticercus was first noticed here in the beef tendered at the Royal Artillery ration stand in May, 1868. For some two years previous to this date condemnations of cyst-infected meat had been frequent at Peshawur, Rawul Pindee, Meean Meer and several other stations in the upper part of the Punjab, and here I had often detected the parasite in meat exposed for sale in the bazaars, but no trace of it had been observed in the Commissariat beef, either by myself or any other medical officer who had preceded me.

“From May, 1868, to November, 1869, ‘cyst’ was more or less frequently found both at the Artillery and 92nd Highlanders’ ration stands; but since the latter date it has almost entirely disappeared.

“The following table shows the quantity of meat destroyed on this account during 1868 and 1869:

+--------+-----------+------------------+---------------+ | Years. | Months. | Number of cattle | Weight of meat| | | | infected. | destroyed. | +--------+-----------+------------------+---------------+ | { | May | 4 | 412 lbs. | | { | June | 1 | 77 " | | { | September | 1 | 130 " | | 1868 { | October | 10 | 1,763 " | | { | November | 14 | 2,010 " | | { | December | 12 | 1,785 " | +--------+-----------+------------------+---------------+ | { | January | 21 | 4,062 lbs. | | { | February | 16 | 2,341 " | | { | March | 14 | 2,209 " | | { | April | 5 | 856 " | | 1869 { | May | 2 | 220 " | | { | June | 1 | 122 " | | { | July | 1 | 194 " | | { | August | 3 | 464 " | | { | September | 2 | 218 " | | { | October | 4 | 615 " | | +-----------+------------------+---------------+ | | Total | 111 | 17,478 lbs. | +--------+-----------+------------------+---------------+

“The whole of this meat was otherwise well fed and of excellent quality. The waste of so much good food led me to make inquiries; 1st, as to the sources from which the cattle obtained the Tænia ova, and the best means for preventing their infection; and 2ndly, as to whether or not any evil results followed the consumption of this meat when properly cooked.

“From information obtained from the Commissariat Officer I found--1st. That the infected cattle had been purchased by native dealers from various parts of the district, not from any particular locality. 2ndly. That when brought in they were lean, and on an average required from two to three months’ feeding at the Commissariat cattle yards before they were fit for the shambles. 3rdly. That their food consisted of the grass they could pick up on the grazing grounds of cantonments, supplemented by such an allowance of grain and _bhoosâ_ as their condition required.

“They were supposed to be watered at a trough with water drawn from a well, but on closely inquiring as to this, it transpired that they very frequently were taken to a large dirty tank near the yard for their water. The question which occurred to me was, were the cattle infected before their purchase by the Commissariat, or was there anything in their feeding to account for it after purchase? I am inclined to the latter opinion for several reasons, thus:--In the large number of the diseased cattle, the Cysticerci were of remarkably small size; many of them having no capsules, except such as were formed by the surrounding structures, and not being more than 1/8 to 1/4 of an inch in diameter. Although the dry food given to the cattle was doubtless good, still much of the water they got during 1868 was probably filthy. The tank previously referred to was situated close to the huts of the camel drivers. These men are all Mussulmans from Cabul, Peshawur, or thereabouts, and many of them are infected with _Tænia mediocanellata_. Human filth was often to be seen on the banks of the tank, and microscopic examination of mud and stagnant water taken from the margin exhibited _Tænia_ ova.

“The conditions above shown must have been eminently favorable to keeping up a constant supply of ova, and the fact that Cysticercus entirely disappeared from amongst the cattle a few months after means had been taken to secure them a good supply of well water, seems to confirm the view that this tank must have been the source of a large amount of, if not all, the infection.

“It has been suggested that Cysticercus can be detected before the animal is killed by an examination of the tongue. In exceptionably severe instances this is probably correct, but then it would be equally observable in some other parts of the body. Major Biggs, Commissariat Officer here, tells me of an animal he saw at Rawul Pindee, in which immense clusters of cysts could be felt at the root of the tongue and under the skin in several parts. After examining a very large number of tongues of ‘cysted’ animals, my experience is that it is found in the soft muscles and cellular tissues at the root of the tongue, perhaps more frequently than anywhere else; but I have never seen a case in which there was a chance of detecting it before death.

“The most common situations in which it has occurred in the ration meat have been the gluteal, psoas, and lumbar regions. In many instances only from one to ten cysts have been found on cutting the carcase into small pieces, and I have no doubt that it often passed without detection.

“During 1868 and 1869 I from time to time obtained pieces of beef badly infected with _Cysticercus_, and made some experiments as to the results of its consumption under different conditions.

“After explaining to them the possible consequences of eating it a buttock of beef studded with _Cysticercus_ was given to three natives of low caste. They all declared that they were free from _Tænia_, or, to use their own term, “Kadhu dana.” The meat they cooked in their own way. These men were under my observation for some six months. Two of them had no symptom of _Tænia_, but the third, who was a low-class Mahommedan syce, and had probably eaten the meat in a very raw state, developed a _Tænia mediocanellata_ in about three months.

“My own sweeper ate this cyst-infected beef regularly two or three times a week for some months. He cooked it well generally as an ordinary stew, and has never shown a sign of having tapeworm.

“Into the food of a boy of low Hindoo caste, but who had never eaten beef, two scolices of Cysticercus were surreptitiously introduced, the result being that, between three or four months afterwards, he applied for some tapeworm medicine.”

[The two successful experiments here reported are evidently the same as those that I have referred to (p. 72) as having been performed by Dr Oliver, of the Royal Artillery, stationed at Jullundur. The report continues as follows:]

“_Tænia mediocanellata_ is very common amongst the Mussulman population of the Punjab, and from reliable sources I am informed that the lower classes amongst them are in the regular habit of eating half-cooked beef; indeed, prefer it so, and it is amongst these people that tapeworm is so prevalent.

“But it is not only thorough cooking that is required to guard soldiers in India from the ill effects of eating measly meat; there is want of cleanliness in the general arrangements of the kitchens and serving of meals, which must offer great facilities for the introduction into the food of Cysticercus.

“Barrack cooks, unless constantly looked after, are utterly careless as to the washing of chopping blocks, tables, dishes, &c. The dish or pot cover on which the meat is placed when raw is often used without washing for serving the piece up for dinner, and I have myself picked up a _Cysticercus_ from the table on which a cook was preparing food. The dangers too of the parasite being conveyed by the cook’s unwashed hands to the plates in which meals are served, and the common practice of using the same knife for cutting up meat, and afterwards, without washing it, for other culinary purposes, must not be overlooked. With good selection and careful feeding there seems to be every probability that Cysticercus would soon almost or completely disappear from our Commissariat cattle. If they were entirely stall-fed and watered from wells there could scarcely be a possibility of infection after their purchase.

“Perhaps with the trench system of conservancy, which will necessitate the growing up crops, a sufficient quantity of root and other green produce may be obtained from cantonment lands set apart for this purpose, to supply green fodder for the cattle.”

The important question as to whether the presence of cysts detected at the root of the tongue could be made available for the purposes of diagnosis was made the subject of special report through the agency of executive Commissariat officers, and they testified to its practical valuelessness in the following terms:

“_Jullundur._--No appearance of cyst has been found at the root of the tongues of any of the cattle. A medical officer was asked for assistance in making search for the cysts, but he also found none.

“_Rawul Pindee._--It is utterly impossible to discriminate before slaughter, from any outward symptoms, cattle that are cyst infected.

“Every endeavour has been made to discover by close and careful scrutiny before slaughter the cyst-infected cattle, but the result has been in no way satisfactory.

“_Sealkote._--All endeavours to discover any symptoms of the infection by examination of their tongues, while the animals were living, have been unsuccessful.

“_Mooltan._--The mouth and tongue of a large number of living cattle have been examined before slaughter, but in no single instance has the infection been so detected.

“Dr. Ross’s plan of examining the tongues of all animals at time of purchase is not feasible, as they are usually very wild and frightened, and often dangerous to approach.

“_Peshawur._--In probably 99 cases out of 100 it is utterly impossible to discover cyst infection in cattle previous to slaughter by examination of their tongues. In only one instance has it been so discovered, and that was from the animal’s having a number of small lumps over the body which were also apparent on the back part of the tongue. When the tongue is infected the ‘cyst’ lies so far at the very root of it that it cannot be seen in the live animal.”

From Mooltan a specially interesting report was made by Dr Alexander Neill, who says:--

“I have carefully examined the mouth and tongue of a large number of living cattle, and of those slaughtered for issue as rations, and in no single instance did I find such cysts. These cattle were healthy.

“In a case that died, and in which cysts existed, I could discover nothing abnormal in or under the tongue.

“If such ‘cysts’ exist, or if such enlargements of the sublingual glands are found, I argue that they are not a diagnostic sign of what is termed ‘cyst infection,’ or more correctly ‘_Cysticercus bovis_,’ for in the recent outbreak of cattle disease in England, one most prominent symptom of that disease was a bunch of grape-like swelling under the tongue, which in advanced cases suppurated, and to a casual observer would have been called cysts or ‘bags of matter.’

“If such swellings are found in a bullock that is sick, it is merely symptomatic of an inflamed condition of the whole mucous surface of the intestinal canal, and not of any localised disease, such as Cysticercus, the above-mentioned swellings being merely inflamed sublingual glands.

“In the pig the diagnostic sign of swellings of the glands or ‘cyst’ under the tongue is not found in ‘Cysticercus,’ and the disease called ‘measles’ is not ‘Cysticercus,’ but a mere superficial inflammation of the skin and a symptom of fever. ‘_Cysticercus cellulosus_,’ as its name shows, infects the cellular tissue only of the pig, and cannot be discovered in life by any abnormal condition of skin.

“In ‘measles’ these swellings are found, because intestinal mucous membrane sympathises with eruption on the skin and are then merely inflamed glands, not cysts.”

Dr Neill concludes his report by remarking that the larvæ of the beef tapeworm can “only arrive at maturity in the mucous membrane of horned cattle,” and not in the cellular tissue. This is an error on Dr Neill’s part; but in adducing these instructive extracts from the Government Reports my chief object has been to show the prevalence of Cysticercus in the North-West Provinces of the Indian Peninsula. I may say that a large proportion of my tapeworm-infected patients have been officers from the Punjab, and one of these victims told me that when he superintended the serving out of rations to the troops, “he (and those who acted with him) sent the meat away to be burnt, even when they only detected a single cyst in any given carcase.” It is needless to remark that such a waste of valuable food is altogether reprehensible.

Some people, including not a few of the profession, make light of the occurrence of tapeworm, and I have seen many patients who had been told by their usual medical advisers that the presence of the worms was of little consequence. To account for this wide-spread error there is some basis in the fact that by far the majority of infested persons suffer only the trifling inconvenience arising from the passage _per anum_ of the proglottides; moreover, the less civilised the tapeworm-bearers happen to be, the less are they likely to suffer. The recorded experience of Kaschin, before referred to, where 500 hospital patients, in the Baikal district, had tapeworm, although all of them were being treated for other disorders, affords another argument tending to the same conclusion. On the other hand, amongst Europeans only a small percentage of tapeworm-patients suffer severely. But without trenching upon the symptomatology and prognosis of tapeworm disease, I may remark that I have (in my Manual) summarised the whole facts of cysticercal prevalence within the compass of two brief propositions:--1. The prevalence or the rarity of Cysticerci in cattle in any given country must be determined primarily by the habits of the people; for since the beef measle can only result from the ingestion by the ox of the eggs of the _Tænia mediocanellata_, it is clear that the degree of infection of cattle will correspond with the facilities offered by egg-dispersion. 2. It may be affirmed that the frequency of this particular species of tapeworm amongst the people occupying any given area will bear a strict relation to the amount of underdone measly beef consumed by the inhabitants.

Another question, and one of great interest to sanitary science, is that which I have raised in reference to the period that nature requires for the destruction of the Cysticerci, or, in other words, for the performance of a natural cure by calcareous degeneration of the parasites. I have shown that all kinds of tapeworm larvæ (measles, bladder-worms, cœnuri, and so forth) have a natural life-epoch assigned to them, and in one of my experiments on a Dutch heifer or young cow I demonstrated that a period of ten months was more than sufficient to ensure the perfect destruction of the Cysticerci of cattle. Moreover, this law or process of natural cure is not limited to cestode parasites, but affects all other kinds of internal parasites in one or other of their juvenile stages of growth. In the flesh of my experimental animal I estimated that there were not less than 12,000 of these degenerated Cysticerci. This positive contribution to our knowledge of the limits assigned by nature to the epoch of larval activity is not merely one of abstract scientific interest, but it has important practical bearings, inasmuch as it points out in what way an entire herd of cattle (known to be measled by the post-mortem examination of one animal previously selected for the purpose, or for that matter, by the rather barbarous act of excising and examining a fragment of the muscle of a living one) may be freed of its parasitic guests; and it also shows how all risk of propagating tapeworm, apart from the question of subjecting the flesh to a certain temperature, may be effectually prevented. The stockowner has but to remove his animals for six or eight months to localities where no fresh infection can occur, when, at the expiration of the time mentioned, all those Cysticerci that existed in the beasts at the time of the transfer will have perished. The flesh of the animals may then be eaten with impunity, whether well cooked or raw. This is an important teaching deducible from experimental inquiry, and I am rather surprised that it has hitherto escaped the notice of persons who, though they affect to ignore the value of scientific researches, are particularly anxious to parade their practical knowledge, which, unhappily, too often proves a mere cloak for ignorance.

The memoir by Giacomini already quoted (p. 65) affords interesting details respecting a case in which there was a most unusual degree of infection of the human body by Cysticerci. Dr Giacomini instituted a searching comparison between the human measles procured by himself and those of the pig sent to him by Professor Perroncito. In the human Cysticerci he noticed a greater adherence of the capsule to the enclosed measle, and he also observed that while the human measle-heads either displayed thirty-two, or in some few cases thirty-four hooks, in two differently sized circles of fifteen or sixteen each, the pig-measles, on the other hand, carried only twenty-four hooks to the double circle of equal circumference; consequently the hooks appeared to be more crowded together in the human parasite. This fact, Giacomini remarks, does not of itself constitute an essential specific difference, since variations of the kind not unfrequently occur in Cysticerci occupying one and the same host. Even the beef-measle is not necessarily confined to one species of host, since Zenker has succeeded in rearing it in a goat.

Although the substance of the above-recorded conclusions was originally communicated by me, anonymously, to a professional periodical, I have considered this work a suitable medium for a fuller discussion of the subject. Its importance in relation to the public health and the supply of meat-food has not received the attention it deserves.

BIBLIOGRAPHY (No. 13).--_Balert, B._, ‘Die Bandwürmer,’ &c. (pamphlet), 1877.--_Bertolus, G._, ‘Diss. sur les metamorph. des cestoïdes,’ Montpellier, 1856.--_Cobbold, T. S._, “On the Production of the so-called ‘Acute Cestode Tuberculosis’ by the Administration of the Proglottides of _Tænia mediocanellata_” (with Mr Simonds), in ‘Proc. of the Royal Society’ for May 4th, 1865; repr. in the ‘Veterinarian’ for 1865, p. 513.--_Idem_, “Experimental Investigations with Cestoid Entozoa,” in ‘Linn. Soc. Journ.,’ vol. ix, p. 170; also for July, 1865, p. 141.--_Idem_, “On Beef, Pork, and Mutton, in relation to Tapeworms,” in ‘Brit. Assoc. Rep.’ for 1865, p. 102, and in ‘Appendix to Treatise on Tapeworms and Threadworms,’ 1st Edit., 1866, p. 73; also in ‘Med. Times and Gaz.’ for Sept. 23rd, 1865, p. 343.--_Idem_, “Remarks on Entozoa,” in ‘Brit. Assoc. Rep.’ for 1865, p. 102; also on “Cystic Entozoa from Veal and Mutton,” in the ‘Path. Soc. Trans.’ for 1866, vol. xvii, p. 462.--_Idem_, “Entozoa found in a Westphalian Ham;” report in ‘Athenæum’ for March 27th, 1869, p. 442; also in ‘Brit. Med. Journ.’ for March 20th, 1869.--_Idem_, “Note on Beef Measles from a Cow,” in ‘Path. Soc. Trans.,’ vol. xvii, p. 463, 1866; also in the ‘Lancet’ for Feb. and August, 1865, p. 249.--_Idem_, ‘Entozoa,’ &c., p. 235 _et seq._, 1864; and in ‘Supp.,’ sections iii, iv, v, 1869.--_Idem_, ‘Tapeworms,’ 3rd Edit. (with 100 cases), 1875, p. 11.--_Idem_, ‘Manual of the Internal Par. of Domesticated Animals,’ chap. iii to vi, 1874.--_Idem_, ‘Worms,’ Lectures i to xi, 1872.--_Idem_, “On the Parasites of our Food-producing Ruminants (Cantor Lectures),” in the ‘Journ. of the Soc. of Arts,’ 1871.--_Idem_, “On the Entozoa of Abyssinia” (Lecture), in ‘Lancet,’ 1867.--_Idem_, “Remarks on Eighty Cases of Tapeworm,” ‘Lancet,’ June, 1874.--_Idem_, “Revised List of Entozoa, with notes and references (the beef tapeworm, No. 15, and the beef measle, No. 25),” in the ‘Veterinarian,’ Dec., 1874, and Feb., 1875.--_Idem_, (anonymously), “Cysticerci, being a review of the writings of Pellizzari, Tommasi, Perroncito, Lewis, Giacomini, &c.,” contributed to the ‘Lond. Med. Record,’ 1874, p. 642 _et seq._; repr. in the ‘Veterinarian,’ Jan., 1875.--_Idem_, “Notice of a Discussion by Paul, Martineau, Créquy, Delioux de Savignac, Trasbot, and others, respecting the Source and Treatment of Tapeworm,” ‘Lond. Med. Rec.,’ July, 1874, p. 472.--_Idem_, “Review of the Writings of Oliver, Fleming, Hewlett, Lewis, and others, on the Cystic Disease of Animals,” ‘Lond. Med. Rec.,’ June, 1873, p. 339.--_Idem_, “Further Experimental Researches with the Eggs of the Beef Tapeworm,” the ‘Veterinarian,’ Aug., 1875.--_Idem_, “Remarks on Perroncito’s Researches,” the ‘Veterinarian,’ Dec., 1877.--_Dardel, A._, “Sulla frequenza della Tenia in Savoia,” ‘Giorn. d’Accad. di Med.,’ 1868.--_Davaine, C._, ‘Traité’ (1. c. Bibl. No. 1), 1860.--_Idem_, “Les Cestoides,” in ‘Dict. Encyclopédique des Sci. Med.,’ 1875.--_Fleming, J._, ‘Indian Med. Gaz.,’ 1869.--_Fock, H. C. A. L._, ‘De Lintworm en het middel om hem mit te drijven,’ Utrecht, 1878.--_Fritsch, G._, “Zur differentiellen Diagnose von _T. solium and T. mediocanellata_,” ‘Berliner Klinische Wochenschrift,’ 1874.--_Gamgee, J._, “Entozoa in Veal and Beef” (Letter on), ‘Lancet,’ 1865.--_Giacomini, C._, ‘Sul _Cyst. cell. hominis_ e sull _Tænia med_, contrib. alla studio dei Cestoidi Parrassiti dell’ Uomo,’ Torino, 1874.--_Heller, A._, “Darmschmarotzer,” in von Ziemssen’s ‘Handbuch der speciellen Pathol. und Therapie,’ s. 598 _et seq._, 1876.--_Hewlett_, ‘Health Officer’s Report,’ Bombay, 1870.--_Krabbe, H._, ‘Beretning om 100 Tilfælde af Bœndellorm hos Menesket iagttagne her i Landet (Aftryk af Ugeskrift for Læger),’ 1869.--_Küchenmeister, F._, ‘Ueber Cestoden im Allgemeinen und die des Menschen insbesondere, hauptsählich mit Berücksichtigung ihrer Entwickelungsgeschichte, geographischen Verbreitung, Prophylaxe und Abtreibung; specieller Theil. Zittau,’ 1853.--_Idem_, ‘Parasiten’ (1. c. Bibl. No. 1), 1855, Eng. Edit., London, 1857.--_Laboulbéne, A._, “Sur les Tænias,” ‘Mém. de la Soc. Méd. des Hôpit.,’ 1876.--_Idem_, ‘Anat. Pathologique,’ 1879, p. 962.--_Letheby_, “On Diseased Meat,” ‘Med. Times and Gaz.,’ 1867.--_Leuckart, R._, ‘Die Menschl. Par.,’ Bd. i, s. 285 and s. 747, 1864.--_Levi_, “Della freq. della tenia,” &c., ‘Giorn. Veneto di Scienz. Med.,’ 1874.--_Lewis, T. K._, “A Report on the Bladder Worms found in Beef and Pork” (‘App. B. to 8th Ann. Rep. of the Sanit. Commiss. with the Gov. of India’), Calcutta, 1872.--_Masse, E._ et _Pourquier, P._, “Le Tænia inerme et la lardrerie du Bœuf, Nouvelles Expériences,” &c., in ‘Montpellier Med. Journ. Mens. de Méd.,’ p. 220, 1876.--_Mosler_, ‘Helminthogische studien und Beobachtungen,’ Berlin, 1864. _Neill, A._, “Letter, forming the fifth of a series of important articles on Cyst-infected Cattle, and on the prevalence of Cysticercus in Beef,” reported by the Inspector General (I. M. D.), in the ‘Madras Monthly Journ. of Med. Sci.,’ Feb., 1873; repr. in the ‘Veterinarian,’ July, 1873.--_Nitsche, H._, “Untersuchungen ueber den Bau der Tænien,” ‘Sieb. und Köll. Zeitschrift,’ 1873.--_Oliver_, “Rejections of Ration Beef on account of Cystic Disease” (l. c. _supra_), ‘7th Rep. of the Commiss.,’ p. 82, Calcutta, 1871.--_Perroncito E._, “Della panicatura negli animali,” ‘Annali della R. Accad. d’Agricolt. di Torino,’ vol. xv, 1872.--_Idem_, “Sulla morte del _Cyst. cell._ delle carni del majale;” _ibid._, 1872.--_Idem_, “Ueber die Lebenszähigkeit des _Cyst. cell._ und anderer Eingeweidewürmer,” ‘Zeitsch. f. prakt. Veter.-Wissenschaften,’ Bern, 1876.--_Idem_, ‘Della Grandine o Panicatura nell’ Uomo e negli animali,’ Torino, 1877.--_Idem_, “Esperimenti sulla produzione del cisticerco nelli carni del bovini, coll’ amministrazione di anelli della _tænia med._ dell’ uomo,” ‘Lo Studente Vet.,’ Parma, 1876, p. 146.--_Idem_, “Sulla tenacita,” &c., _ibid._, 1877, p. 194.--_Idem_, “Esperimenti sulla prod. del Cyst. della _T. med._ nelle carni dei Vitelli,” ‘Estr. della Annali d. R. Accad. d’Agric. di Torino,’ vol. xx, 1877.--_Idem_, “On the Tenacity of Life of the Helminths, and their corresponding Larval Forms in Man and Animals,” the ‘Veterinarian,’ July, 1877, p. 457.--_Idem_ (with similar title, including notice of experiments), the ‘Veterinarian,’ Dec., 1877; partly from ‘Osservatore Gaz. d. Cliniche di Torino,’ and from ‘Archivvo per le Sci. Med.,’ vol. i, 1877.--_Idem_, “On the Tenacity of Life of the _Cysticercus_ in the flesh of Oxen, and on the rapid development of the corresponding _T. mediocanellata_ in the Human Body,” the ‘Veterinarian,’ Dec., 1877, p. 817.--_Probstmayr_, ‘Jahrb. der Münchener Thierarzneischule,’ 1869.--_Rochard_, “Note sur la fréquence du _Tænia mediocanellata_ en Syrie, et sur la présence du cysticerque qui lui donne naissance, dans la chaire musculaire des bœufs de ce pays,” in ‘Bulletin de l’Acad. de Méd.,’ 1877, tom. vi, p. 998.--_Thudichum, J. W. L._, “On the Parasitic Diseases of Quadrupeds used as Food,” ‘Privy Council Med. Officer’s Rep.’ 1865.--_Sommer, F._, “Ueber den Bau und die Entwickelung der Geschlechtsorgane, von _Tænia mediocanellata_ und _T. solium_,” in ‘Siebold and Köll. Zeitschrift,’ Bd. xxiv, s. 499, 1874.--_St Cyr_, “Deux Experiences,” &c., ‘Journ. de l’Anatomie, de Robin,’ p. 504; and in ‘Lond. Med. Rec.,’ by Higgs, vol. i, 582, 1873.--_Tommasi, T._, ‘Appendice (to Cobbold’s) Parasiti Interni degli Animali Domestice,’ p. 161, Firenze, 1874.--_Van Beneden, P. J._, “Iconographie des Helminthes ou des vers parasites de l’homme” (Vers Cestoïdes, pl. ii), Louvain, 1860.--_Welch, F. H._, “Observations on the Anatomy of _Tænia mediocanellata_,” ‘Quart. Journ. of Microsc. Science,’ vol. xv, 1875.--_Zenker_, in ‘S. B. Soc.,’ Erlang. iv, s. 71.--_Zurn_, ‘Zoopathologische und physiol. Untersuchungen,’ 1872.

_Tænia solium_, Linneus.--This cestode was formerly known as the common tapeworm, but in England it is of far less frequent occurrence than the beef tapeworm. In contradistinction it is best to speak of it as the pork tapeworm. Though only one specimen is usually present, the bearer may entertain several worms of this species at one and the same time. The parasite has been known to science from the earliest times, though possibly not earlier than the measles, or Cysticerci, from which it originates. Hippocrates, Pliny, and Aristotle describe the full-grown worm; and, in regard to the larvæ, some have gone so far as to express their belief that the prohibition of swine’s flesh as food amongst the Jews and other Oriental people, was dictated by sanitary considerations. Weinland has suggested that the Mosaic commandment not to eat pork may have originated in an old popular notion “of the fact that tapeworm sometimes comes from this food.” Weinland’s hypothesis is probably correct, for if one supposes Moses to have been supernaturally informed that pork would produce tapeworm disease, one naturally asks why veal and beef should not also have been prohibited, seeing that these meats also frequently harbour tapeworm larvæ.

A perfect pork tapeworm presents itself to the eye of the observer as a long, soft, white, jointed strobile, which, when alive, elongates and contracts itself with facility. Though commonly spoken of as a single creature, it is a compound of many individuals. These are variously called “cucurbitini,” “zooids,” “proglottides,” “segments,” “links,” or “joints.” When fully grown the segments are capable of detaching themselves and of enjoying a free and independent existence. Very annoying it is to the human bearer to be continually reminded of his unwelcome “guests” as they seek to quit his interior.

The head of _Tænia solium_ is seldom seen in anatomical museums, although the evacuation of pork tapeworms is not of rare occurrence. Placed under the microscope, the head displays a quantity of dark, almost black, pigment granules, which are abundant at the base of the rostellum and in the neighbourhood of the hook-fangs. They are equally present and abundant in the pork measle proper, and in measles derived from the human subject. The cephalic hooks of this cestode are comparatively large, those of the greater circle individually measuring 1/156″, whilst the smaller hooks have a length of about 1/220″.

The male reproductive organ consists of a number of small vesicles or sacs, in which filiform spermatozoa have been detected, these latter, when ripe, being conducted by a _vas deferens_ into a seminal pouch, from which a canal passes laterally into the penis; the latter organ, in its retracted condition, being lodged within a flask-shaped sheath or cirrhus-pouch. The female organs are somewhat more complicated. They consist of two masses of vitelligene glands occupying a limited space, a small ovarium, a centrally-placed and largely-developed branched uterus, canals of outlet leading from all these organs, and enlargements of the main passages to form internal seminal reservoirs; also, a vaginal canal, which is widened at its termination to form a receptaculum for the curved penis.

In addition to the above-named structures, the entire series of joints from the head downwards are traversed by a set of vascular canals, which are doubled in the region of the head. These form the so-called aquiferous system. There are two main channels, one passing down on either side of the worm, both being connected by transverse vessels, which occur singly at one end of every joint.

The eggs in their mature condition are globular, and contain a six-hooked embryo. They present an average diameter of 1/694 of an inch, the shell itself measuring about 1/4000″ in thickness. In 1856 I observed that many of the eggs, whilst still within the uterine branches, displayed an outer envelope, very delicate in structure and totally dissimilar from the egg-shell proper. This has since been more accurately described by Weinland, Van Beneden, and Leuckart. The outer membrane, according to the last-named authority, constitutes the primitive yolk-membrane, within which a part of the yolk-contents separates to form the true egg and embryo by a process of daughter-cell formation. The remaining part of the yolk forms a granular mass, being probably concerned in the formation of the true chitinous shell. The true shell displays a series of radiating and circular lines; the former, however, are more conspicuous than the latter, being due, according to Leuckart, to the presence of a series of fine rod-like chitinous elements, which are formed on the external surface of the original true shell-membrane. The enclosed embryo is furnished with six boring spines, arranged in three pairs, its granular body being invested by an extremely delicate skin-membrane, which is separated from the inner surface of the shell by a clear transparent fluid. The embryo measures 1/1250″ in diameter.

The scolex or higher larval stage of growth forms the well-known pork measle or _Cysticercus_ (_telæ_) _cellulosæ_ of authors. The smallest measles found by Leuckart measured 1/25″ in length. They were obtained from the brain, liver, and intermuscular substance of a pig fed with proglottides about thirty days previously. Only those specimens, however, occurring in the liver at this early period displayed an outer membrane proper to the worm itself, the others being simply invested with capsules formed out of the connective tissues of the host. Many measle-masses in the same host were much larger, presenting an average diameter of 1/6″. The smallest already displayed a smooth, transparent, homogeneous, outer, cuticular membrane, overlying a double, finely-granular corium, the latter being traversed by a branched system of aquiferous vessels. These vessels proceed from a central spot, which marks the position of the so-called head-cone, or _receptaculum capitis_. It is, in fact, the first well-marked indication of that flask-shaped capsule within which the head, neck, and body of the Cysticercus is formed, and which Goeze long ago very aptly compared to a lantern. As growth proceeds, a central granular mass forms the true foundation of the head, its upper or stalk-like extension becoming the future neck and body. Further changes result in the evolution of the internal water-vascular system, the calcareous corpuscles, the marginal transverse foldings of the body, the four suckers, the rostellum, and, in particular, the double coronet of hooks. All these metamorphoses were minutely followed and described by Leuckart, who found the development of the larva to be completed within the space of ten weeks.

As regards the injurious effects of this parasite upon man, it may be said to act prejudicially in three separate ways. I have remarked in my ‘Entozoa,’ that this parasite may cause disease and death both by its action in the larval and adult states. It may likewise injure us by rendering the flesh of swine unwholesome.

When one or more sexually-mature tapeworms have developed themselves within the human intestine, they are apt to give rise to a variety of unpleasant symptoms, more or less marked according to the habit or irritability of the patient. According to Davaine (p. 103 of his ‘Traité’) the principal features are “vertigo, noises in the ears, impairment of sight, itching of the nose and anus, salivation, dyspepsia and loss of appetite, colic, pains over the epigastrium and in different parts of the abdomen, palpitation, syncope, the sensation of weight in the abdomen, pains and lassitude in the limbs, and emaciation.” In ordinary cases there is always more or less anxiety and restlessness; but in severe cases the sympathetic symptoms are very strongly marked, showing themselves in hysterical fits, chorea, epilepsy, and epileptiform seizures, attended by more or less alarming convulsions.

Amongst some of the more interesting and remarkable cases recorded in our English journals, I may instance that of Mr Hutchings, where a complete cure followed the evacuation of the worm which had produced convulsions. Mr Tuffnell records a case where irritability of the bladder and stricture of the urethra were entirely dependent on tapeworm, as proved by the subsequent recovery. At a meeting of the Pathological Society, in 1853, Dr Winslow mentioned his experience of three or four cases of mania arising from tapeworm; whilst on the same occasion Drs Ryan and Davey each recorded a similar instance. A case has also been previously published by Mr W. Wood. At a meeting of the London Medical Society, held on the 10th of April, 1837, Dr Theophilus Thomson (during an interesting discussion on this subject) stated the facts of a case where the presence of tapeworm had given rise to a tumultuous action of the heart, this symptom entirely disappearing after evacuation of the worm. Our journals likewise (anonymously) record a considerable number of cases from foreign sources. Thus, in the ‘London Medical Gazette’ for 1840, there is the case of a lady, aged thirty-seven, who had convulsions attended with a complete loss of consciousness, the separate fits lasting an hour at a time. The passage of the worms effected a complete cure. In the same journal for 1838, there is also the case of a younger lady (aged twenty-seven) suffering from epilepsy, in whom a complete cure had been similarly brought about; here, however, in addition to a single specimen of the _Tænia solium_, there were two lumbrici present. This journal also gives Ettmüller’s case, where eighteen tapeworms were the cause of hysteria; and likewise the case published by Steinbeck, where the symptoms presented an altogether peculiar character. More precise references to some of the above cases will be found in the ‘Bibliography’ below; and I may also refer to my published lectures on Helminthology and especially to my separate work on Tapeworms, where particulars of one hundred cases are briefly recorded. These were all average cases occurring to me whilst in private practice. Davaine’s book also abounds with remarkable cases.

Whilst the adult worm is capable of producing serious and even fatal mischief to the bearer, the larvæ or measles much more frequently prove fatal. The Cysticerci may develop themselves in almost any situation in the human body, but they occur most commonly in the subcutaneous, areolar, and intermuscular connective tissue; next, most commonly in the brain and eye, and lastly, in the substance of the heart and other viscera of the trunk.

In my ‘Entozoa’ I have stated that probably not less than one hundred cases have been observed where death had resulted from Cysticerci in the brain. Griesinger alone collected between fifty and sixty such cases. Mental disturbance occasioned by the presence of measles in the brain may occur with or without epilepsy. When Griesinger states that “the epilepsy from Cysticercus is in all respects like cerebral epilepsy and the psychical disturbances have nothing characteristic about them,” he tacitly admits the impossibility of correct diagnosis during life.

Since the publication of Griesinger’s well-known memoir on Cysticerci of the brain, many similar cases have appeared, and amongst the more recent of these is one by Dr Frédet in which the victim was a young man twenty-two years of age. Though apparently in good health he fell dead in the street; the fatal result being due to the presence of a Cysticercus within the _pons Varolii_.

Many other cases of earlier date are especially noteworthy. Thus Mr Toynbee recorded a case where an hydatid (which I take to have been the _Cysticercus cellulosæ_) situated in the middle cerebral fossa beneath the _dura mater_, but in this instance death ensued from other causes. Mr Ottley gives the case of a woman aged forty, where an undoubted Cysticercus in the brain gave rise to distressing fits, convulsions, and death. Then, again, there was Dr Burton’s workhouse patient, only twenty years of age, who was found dead in bed, but who at the time of admission merely complained of pain in the head. After death, four hydatids (_Cysticerci_) were found in the _tuber ancillare_ at the summit of the spinal marrow. M. Bouvier’s similar case is also reported in our periodicals. Of instances where Cysticerci occupied the cavity of the eye, we have one or two cases by Mackenzie of Glasgow, one by Mr Rose of Swaffham, and others by Windsor, Logan, and Estlin. Amongst the more peculiar cases, I may mention that described by Dr Greenhalgh in the ‘Lancet’ (1848), where the Cysticercus was lodged within the substance of the lip. Five similar cases are likewise recorded by Heller of Stuttgard. Then there is Dupuytren’s case of a Cysticercus ensconced within the great peroneus muscle; and also Fournier’s, where several of these scolices were said to have been found in a boil. The so-called _Trachelocampylus_, discovered by Frédault in the human brain, was neither more nor less than a common _Cysticercus cellulosæ_.

It is worthy of remark, as Griesinger has also observed, that in cases where the Cysticerci have taken up their temporary residence in the brain, they are usually found, post mortem, in the grey cortical or peripheral substance of the cerebrum. The particulars of such a case are given in my ‘Entozoa’ where the victim suffered from epileptic fits due to the presence of numerous Cysticerci (fig. 24). The patient was under Mr Hulke’s care.

As regards infection by the adult worm it is not alone sufficient that we avoid underdone _meat_, as brought to the dinner-table, but we must be especially careful to have our sausages well cooked. Under ordinary circumstances, we are safe for the following reasons:--No respectable butcher will knowingly supply us with pork or with sausages which are measled. Even in the case of underdone meats, in whatever way prepared, it is usually only a small portion which is unaffected by cooking. As we have seen a temperature of 140° Fahr. is sufficient to kill the Cysticerci.

The successful rearing of pork measles by experimentation with the eggs of _T. solium_ has been accomplished by many helminthologists, amongst whom may be particularised Van Beneden, Leuckart, Küchenmeister, Haubner, Gerlach, and Baillet. The converse experiment of rearing the adult worm from the Cysticercus was first successfully undertaken by Küchenmeister on a condemned criminal; Leuckart, Humbert, and others having repeated this method with more or less success.

The dangers arising from infection by swallowing the larval worms or six-hooked embryos are not easily avoided. Our flesh, like pork, thus becomes measled, although certainly not to the spawn-like extent so often seen in the lower animals. A single measle is sufficient to prove fatal; and this humiliating contingency, moreover, is one which we can never be absolutely certain of avoiding. We become the “host” or bearer of the measle by swallowing the fully-developed eggs of the _Tænia solium_. This we may do directly by handling fresh tapeworms, whose eggs, being concealed under our nails or in our clothing, may subsequently be swallowed, and develop within us accordingly. Even a thorough washing of the hands will not ensure absolute security. In like manner, those who partake of choice salads, prepared from the stores of the market-gardener, run a certain amount of risk. The vegetables may have been manured with night-soil containing myriads of tapeworm eggs, or they may have been watered with fluid filth into which the eggs were accidentally cast. In such cases, one or more tapeworm ova will be transferred to the digestive organs, unless the vegetables have been very carefully cleansed. In the same way, one perceives how fallen fruits, all sorts of edible plants, as well as pond, canal, and even river water procured from the neighbourhood of human habitations, are liable to harbour embryos capable of gaining entrance to the human body. One individual suffering from tapeworm may infect a whole neighbourhood by rendering the swine measly, these animals, in their turn, spreading the disease far and wide. As already remarked, measles sometimes occur in great numbers in different parts of the body. Among the more remarkable cases of the multiple Cysticerci are those recorded by Delore (1864) and Giacomini (1874). In M. Delore’s case, about 2000 were obtained post mortem. Of these, 111 occurred in connection with the nervous centres, eighty-four being in the cerebrum, twenty-two in the membranes of the brain, four in the cerebellum, and one within the substance of the medulla oblongata. Dr Knox published a less notable instance in the ‘Lancet’ (1838); and in the year 1857, Dr Hodges, of Boston, U.S., published a case where the cysts, which in size he compared to rice grains and coffee beans, were felt subcutaneously. The coexistence of Tænia and Cysticerci in the same individual has also recently been observed in France (‘Lond. Med. Rec.,’ 1875). Besides these, several remarkable instances have lately been reported by Davy, Tartivel, and others.

To the literature already quoted in connection with the beef tapeworm the following may be added:

BIBLIOGRAPHY (No. 14).--_Aran_, in ‘Archives Gén. de Médecine,’ 1841.--_Baillet_, “Helminthes,” art. in ‘Bouley and Reynal’s Dict. Vétérin.,’ tom. viii, 1869.--_Bécoulet_ and _Giraud_, “On Cysticercus in the Brain,” ‘Bullet. de la Soc. Méd. de Gand,’ 1872; and in ‘Lond. Med. Rec.,’ Feb., 1873.--_Birkett, J._, Cases, ‘Guy’s Hosp. Rep.,’ 1860.--_Bouchut_, “Cyst. in the Brain,” ‘Gaz. des Hôp.,’ 1857, and ‘Journ. für Kinderkrankheit.,’ 1859.--_Bouvier_, ‘Bullet. de l’Acad.,’ 1840.--_Burton_, in ‘Med. Times and Gaz.’ (supposed hydatids), 1862.--_Cobbold_, “On Measly Meat and Measles in Man,” the ‘Veterinarian,’ 1876.--_Czermack_, “Cysticerci causing Insanity,” Corresp.--Blatt, 1838.--_Dalton, J. C._, “Cyst in the Scrotum,” ‘New York Journ. of Med.,’ 1857.--_Davaine_ (see his ‘Traité’ for many additional references; p. 676).--_Davy, R._, “Cysticerci in the Muscles,” ‘Rep. of Lond. Med. Soc.,’ ‘Lancet’ for Nov., 1876.--_Estling_, “Cases of Cysticercus,” ‘Lond. Med. Gaz.,’ 1838-39.--_Frédet_, “Cysticercus in the _pons Varolii_,” in the ‘Lancet’ for June 23rd, 1877 (p. 925), from ‘Giornale Veneto de Scienze.’--_Fournier_, ‘Journ. des Connois. Med. Chir.,’ 1840.--_Griesinger_, “On Cysticerci of the Brain,” from ‘Med. Jahrb.’ in ‘Med.-Chir. Review,’ 1863.--_Harley, J._, “Cyst. in the Brain,” ‘Lancet,’ 1867.--_Hodges, R. M._, “Specimens of _Cyst. cell._, felt as small tumours just beneath the skin, varying in size from that of a grain of rice to that of a coffee bean,” ‘Rep. of Boston Soc. for Med. Improvement,’ in ‘Brit. Med. and Surg. Journ.,’ 1857.--_Hogg, J._, “Obs. on Cysticercus,” in his ‘Manual of Ophth. Surgery,’ 3rd edit., 1863.--_Holler, A._, “_Cyst. cell_., im Gehirne einer Geisteskranken,” ‘Allgem. Wiener Med. Zeitung,’ 1878.--_Logan, R._, “Probable Cases of _Cyst. cell_.,” removed by Robertson, ‘Ed. Med. and Surg. Journ.,’ 1833.--_Mackenzie, W._, “Cyst in the Eye,” ‘Lancet,’ 1848, ‘Lond. Med. Gaz.,’ 1839.--_Mazotti, L._, “Caso di numerosi cisticerchi del cervello e delle meningi,” ‘Rivista Clin. di Bologna,’ 1876.--_Mégnin, P._, “La Ladrerie du porc et le _Tænia solium_,” ‘La France Médicale,’ 1876.--_Putz, H._, “Ueber die Lebenszähigkeit des _Cysticercus cellulosæ_,” &c., ‘Zeitsch. f. pr. Vet.-Wissenschaften,’ 1876.--_Rainey, G._, “On the Structure, &c., of _Cyst. cell._,” ‘Phil. Trans.,’ 1857.--_Rizzetti, G._, “Rendiconto Statistico dell’ufficio d’igiene di Torino per l’Anno 1873.”--_Rudall, J. T._, “Cyst. in the Brain,” ‘Australian Med. Journ.,’ 1859.--_Tartivel, De A._, “Cysticerques multiples dans le tissu cellulaire sous-cutané et dans certain viscères,” ‘Rec. de Méd. Vet.,’ 1876.--_Von Gräfe, A._, in ‘Arch. für Ophthal.,’ 1857.--_Wells, S._, Bourman’s Case, ‘Ophth. Hosp. Rep.,’ 1860.--_Windsor, J._, “Cyst. in the Eye,” ‘Brit. Med. Journ.,’ 1861.

_Tænia tenella_, Cobbold.--I have long been acquainted with the fact that there is a comparatively small human tapeworm which cannot be referred to either of the foregoing species. In the absence of experimental proof, I incline to the belief that the worm in question owes its existence to measly mutton. The sheep harbours an armed Cysticercus (_C. ovis_), which I regard as the scolex of _Tænia tenella_. The specific name (_tenella_) was originally applied by Pruner to a cestode six feet in length, which he found associated with a larger tapeworm. This latter he called _Tænia lata_. Whilst Diesing has pronounced Pruner’s _Tænia lata_ to have been a _T. mediocanellata_, I, on the other hand, consider Pruner’s _T. tenella_ to have been a _T. solium_. Mr J. C. Mayrhofer has suggested its identity with _Bothriocephalus tropicus_. When, some years back, I applied the term _T. tenella_ to a new tapeworm (of which I possess several strobiles) I was quite unaware than any similar nomenclature had been adopted by Pruner. From the few facts supplied by Pruner and Diesing, I cannot suppose that our cestodes are identical. Unfortunately my specimens are imperfect, wanting the so-called head. It is not possible to estimate the length of the worm accurately, but the perfect strobile must measure several feet.

On one slide I have mounted nine mature proglottides of a worm which I procured on the 15th Dec., 1875. The segments measure, on the average, exactly 1/10″ in length, and only 1/20″ in breadth. The uterine rosettes are all full of eggs, and their branches so crowded together that I am unable to ascertain their average number. The segments are perfectly uniform in character, their reproductive papillæ alternating irregularly at the margin.

In the autumn of 1872 I caused a lamb to be fed with the proglottides of a tapeworm which I referred to this species. The animal was slaughtered on the 22nd of January, 1873, when the result was stated to have been negative. As I had no opportunity of examining the carcase, I cannot feel quite sure that there actually were no Cysticerci present. On several occasions I have detected measles in the flesh of animals, when none were supposed to be present by those who either assisted me or were professional on-lookers. Assuming my _Tænia tenella_ to be derived from the sheep’s Cysticercus, I think it fitting to describe the mutton measle in this place. Even if _T. tenella_ be not actually the adult representative of the mutton measle (_Cyst. ovis_), it is quite certain that the scolex in question gives rise to an armed tapeworm, and it is almost equally certain that the adult armed cestode resides in man. In Pruner’s case, which is by no means unique, we have seen that two distinct species of cestode may coexist in the human bearer. It is quite possible that some one may yet have the good fortune to detect the beef tapeworm, the pork tapeworm, and the mutton tapeworm, all together in one and the same host.

On five separate occasions I have detected measles in “joints” of otherwise excellent and healthy mutton brought to my own table, and supplied by the family butcher. On several other occasions I have had these parasites brought under my notice; nevertheless, many persons are either unaware of, or actually deny, the existence of these ovine parasites. Thus, MM. Masse and Pourquier, in the ‘Montpellier Med. Journ.’ for Sept., 1876, make the following statement: “The sheep, not being subject to measles, it seems to us natural to employ the raw meat of that animal whenever it is required for nourishment in the treatment of diarrhœa, in weaning children, in phthisis, and for anæmics.” Clearly, if MM. Masse and Pourquier could have brought themselves to believe that English literature is worth consulting on such matters, they would not have made this statement. Incidentally they also observe, when speaking of beef measles:--“Un fait que nous avons remarqué et que nous tenons à signaler, c’est que nous avons trouvé des cysticerques nageant librement dans l’eau où nous avions plongé de la viande infestée de ladrerie.” Certainly this is a novel experience. That measles should not only get out of their cysts, but should have the power of “swimming freely” in the water is a phenomenon which requires explanation. There must have been some error of observation.

It was in the year 1865 that I discovered the mutton measle (_C. ovis_, mihi); but I am not prepared to say that the parasite had never been seen before, since it is alleged that a two-headed Cysticercus was obtained by Fromage from the liver of a sheep (as cited by Davaine). Be that as it may, my discovery was announced in a communication made at the Birmingham meeting of the British Association in the autumn of 1865, and subsequently at a meeting of the Pathological Society of London, on the 3rd of April, 1866 (‘Path. Trans.,’ vol. xviii, p. 463). After these dates further announcements and verifications appeared, amongst which I can only refer to my remarks “On Beef, Pork, and Mutton, in relation to Tapeworms,” forming an appendix to the first edition of my work on Tapeworms, 1866; to the “Remarks on Cysticerci from Mutton,” contained in the fourth chapter of the Supplement to my introductory treatise on Entozoa, where a figure of the parasite is given, 1869, p. 27; to Dr Maddox’s paper “On an Entozoon with Ova, found encysted in the Muscles of a Sheep,” recorded in ‘Nature,’ May 15th, 1873, p. 59; to the ‘Monthly Microscopical Journal,’ June, 1873, p. 245; to my further communications in the ‘Lond. Med. Record,’ Aug. 6th, 1873; to my ‘Manual,’ 1874, pp. 74 and 105, Ital. edit. ‘Nota Dell’ Autore,’ p. 133; and especially to the article headed “The Mutton Tapeworm,” contained in the 3rd edit. of my little volume on ‘Tapeworms,’ p. 12, et seq., 1875.

In regard to the measle itself, I spoke of it as smaller than the common pork measle. The head is 1/30″ in breadth, and is armed with a double crown of hooks, twenty-six in all, the larger hooks each measuring 1/160″ in length. The suckers are four in number, each having a breadth of 1/100″. The neck and head are abundantly supplied with calcareous corpuscles, being at the same time marked by transverse rugæ. The data on which I founded my brief description of the scolex were chiefly based on the examination of a specimen which had been procured by Prof. Heisch from the interior of a mutton chop. Subsequently much fuller details of the structure of the scolex were supplied by the illustrated memoir of Dr Maddox (above quoted). This excellent microscopist, however, announced the presence of immature ova within the Cysticerci themselves. As the notion of the existence of eggs in larval cestodes was altogether at variance with what we know of the phenomena of tapeworm life, I suggested that the author might have mistaken the egg-shaped calcareous corpuscles (which I found so abundant in my own specimens) for the ova. In the interests of truth I felt bound to characterise certain of the conclusions arrived at by Dr Maddox as simply incredible, but I regarded his memoir as forming “an important contribution to our knowledge of the structure of the mutton measle.” I had no idea that in pointing to errors of interpretation I should offend the excellent author. However, a long letter appeared in the ‘London Medical Record,’ in which Dr Maddox showed that he was much vexed that I should have “impugned” the “accuracy of his conclusions.” He defended his position with the support of no less an authority than Dr Macdonald, F.R.S., the distinguished Assistant Professor of Naval Hygiène at the Victoria Hospital, Netley. Dr Maddox says:--“We were quite alive to the anomalous position. Hence the exceptionability of the case rests on more than my own evidence.” In regard to this unfortunate dispute I will only add the expression of my conviction that Drs Maddox and Macdonald will eventually become satisfied that no cestode scolex is capable of displaying either mature or immature ova in its interior.

BIBLIOGRAPHY (No. 15). _Cobbold_ (l. c., _supra_), 1865-75.--_Idem_, “On Measly Meat, &c.,” the ‘Veterinarian,’ Dec., 1876.--_Idem_, “The Mutton Tapeworm (_T. tenella_),” No. 16 in my revised list of Entozoa, the ‘Veterinarian,’ Dec., 1874.--_Diesing, C. M._ (_Tænia tenella_, Pruner nec Pallas), in “Revis der Cephalocotyleen,” ‘Sitzungsb. der Math.-Mat. Class d. k. Akad. der Wissenschaften,’ Bd. xlix, s. 369, 1864.--_Maddox_ (l. c., _supra_), 1873.--_Mayrhofer, J. C._, ‘Die helminth. des Menschen,’ Erlangen, 1854.--_Pruner_, ‘Krankheiten des Orients,’ s. 245, 1847.

_Tænia lophosoma_, Cobbold.--This is a good species notwithstanding the doubts that have been expressed by Heller and others regarding it. I have called it the ridged tapeworm in consequence of the presence of an elevated line coursing the whole length of the body, which measures about eight feet. The reproductive papillæ are remarkably prominent and uniserially disposed throughout the entire chain of proglottides. It is quite an error to suppose that this species is a malformed cestode, or that it has any resemblance to Küchenmeister’s variety of tapeworm from the Cape of Good Hope. Neither does it in the slightest degree resemble the remarkably malformed _T. mediocanellata_ described by Mr Cullingworth. Of the distinctiveness of this parasite as a species, any one may satisfy himself by an inspection of the nearly complete strobile preserved in the Pathological Museum attached to the Middlesex Hospital Medical College. From the examination of several mature proglottides detached from this specimen, I find their average breadth to be one fifth of an inch, by three quarters of an inch in length. Their greatest thickness does not exceed the 1/13th of an inch. The eggs resemble those of other tapeworms, and offer a diameter of about 1/850″ from pole to pole.

BIBLIOGRAPHY (No. 16).--_Cobbold_, “Parasites of Man,” in the ‘Midland Naturalist,’ April, 1878, p. 98.--_Idem_, ‘Tapeworms,’ 1st edit., p. 52, 1866; 3rd edit., p. 27, 1875.--_Cullingworth_ (see Bibl. No. 18).--_Davaine_, ‘Les Cestoïdes,’ l. c., p. 573.--_Heller_, l. c., s. 594.

_Tænia nana_, Siebold.--As regards the dwarf tapeworm, unless Spooner’s case be genuine, there is but one solitary instance on record of its occurrence in the human body; moreover, we have no evidence of its having existed in any other host. It was discovered by Dr Bilharz, of Cairo, at the post-mortem examination of a boy who died from inflammation of the cerebral membranes. Prodigious numbers existed. The largest specimen measured only one inch in length. To the naked eye these worms resemble short threads, and consequently they might very readily be overlooked. The head is broad and furnished with a formidable rostellum armed with a crown of hooks. These hooks have large anterior root-processes, which, extending unusually forward, impart to the individual hooks a bifid character. By far the best account of this worm is furnished by Leuckart, to whom I am indebted for a specimen.

BIBLIOGRAPHY (No. 17).--_Cobbold_, ‘Entozoa,’ p. 244.--_Davaine_ (l. c., Bibl. No. 2), p. 574.--_Heller_, l. c., s. 606.--_Küchenmeister_, l. c., Eng. edit., p. 141.--_Leuckart_, l. c., Bd. i, s. 393.--_Von Siebold_ and _Bilharz_, in Von Sieb. and Köll. Zeitschr., Bd. iv.--_Spooner_, ‘Amer. Journ. Med. Sci.,’ 1873.--_Van Beneden_, ‘Iconographie,’ l. c., pl. iii, fig. 17.--_Weinland, ‘Diplacanthus nanus,’_ l. c., p. 85.

_Tænia Madagascariensis_, Davaine.--This appears to be a well-defined species although the head has not yet been seen. It probably forms the type of a distinct genus. Dr Grenet, stationed at Mayotte (Comores), twice encountered single specimens passed by two young children, eighteen and twenty-four months of age respectively. The proglottides have their genital pores uniserially arranged, and they show, in their interior, remarkable egg-capsules, from 120 to 150 in number in all, each containing from 300 to 400 eggs. These give a long diameter of 1/625″ for the outer envelope and 1/1250″ for the inner, or shell proper. The embryo measures only the 1/2500 of an inch.

A full account of this parasite, with figures, is given by Davaine (‘Les Cestoïdes,’ l. c., Bibl. No. 2, p. 577 _et seq._).

_Tænia marginata_, Batsch.--Although I possess no certain evidence of the occurrence of this parasite in its adult condition in the human bearer, yet there is a tapeworm in the Edinburgh Anatomical Museum referable to this species, which was said to have been obtained from the human body. This worm is very common in the dog.

The principal evidence demonstrating the occurrence of the larval representative of this species (_Cysticercus tenuicollis_) in man, rests upon the two cases recorded in Schleissner’s ‘Nosography’ of Iceland. One of the alleged instances, however, has been proved by Küchenmeister and Krabbe to be that of an echinococcus; so that, after all, there only remains the solitary case observed by Schleissner himself, in which the parasite can fairly be considered as the “slender-necked hydatid.”

To the above, however, may probably be added a specimen preserved in the Anatomical Collection at King’s College, London. It was found connected with an ovarian cyst.

_Tænia elliptica_, Batsch.--This parasite is readily recognised not merely by its delicate form and small size, but also by the circumstance of its supporting two sets of reproductive organs in each mature joint. Their outlets are situated at the centre of the margin of each segment, one on either side. Ordinarily infesting the cat, this worm is a mere variety of the common _Tænia cucumerina_ of the dog. At all events, from the evidence put forth by Eschricht, seconded by Leuckart, there is every reason for believing that one or other of these closely-allied varieties is liable to infest the human body. It was originally stated by Eschricht that he had received a _Tænia canina_ which had been passed by a negro slave at St Thomas, Antilles. This is a synonym of _T. elliptica_, which must therefore be very rare in the human body, possibly only occurring in the negro race.

In regard to the source of this parasite, it has been shown by Melnikow that the scolex of _Tænia cucumerina_ resides in the louse of the dog (_Trichodectes latus_), and thus it is exceedingly probable that the scolex of _Tænia elliptica_ resides in the louse of the cat (_Trich. subrostratus_). How man becomes infested is not so clear. Melnikow’s paper on the juvenile state of this cestode is contained in the ‘Archiv für Naturgeschichte’ for 1869, and is illustrated by a figure of the measle.

_Tænia flavopuncta_, Weinland.--Regarded as a new species, the discovery of this little tapeworm is due to the investigations of Weinland. In Dr Jackson’s ‘Catalogue of the Boston Medical Improvement Society’ an account of the contents of a phial is recorded as follows:--“Specimen of Bothriocephalus, three feet in length, and from half a line to one line and a quarter in width, from an infant. The joints are very regular, except at one extremity, where they approach the triangular form, are very delicate, and but slightly connected, as shown in a drawing by Dr Wyman.” It is further stated that the infant was nineteen months old, and that the worm was discharged without medicine, its presence having never been suspected. It was presented by Dr Ezra Palmer in the year 1842. On examining the fragments, Dr Weinland found, instead of a solitary specimen, at least six different tapeworms, all of them being referable to a hitherto undescribed species. There were no heads; nevertheless, it was ascertained that the worms varied from eight to twelve inches in length, the joints or segments being very broad, and at the same time narrowed from above downwards. The parasite was named “the spotted tapeworm,” in consequence of the presence of yellow spots near the middle of the joint. They represent the male organs of reproduction, the outlets of which, as in my _T. lophosoma_, occur all along one side of the body or strobile. In Weinland’s estimation this parasite forms the type of a new genus which he calls _Hymenolepis_. A full account of the worm is given in his well-known essay (l. c., Bibl. No. 2).

_Tænia abietina_ and other varieties. I can only notice very briefly certain cestodes which either present malformations or which may be regarded as mere _varieties_. First in this series is Weinland’s _T. abietina_. No one who has studied his ‘Beschreibung zweier neuer Tænioiden aus dem Menschen,’ Jena, 1861, can doubt that it is a mere variety of _T. mediocanellata_. The monstrosity described by him as referable to _T. solium_ must also be referred to the beef tapeworm. The variations in the character of cestode proglottides is practically infinite. A museum might be filled with them. Most common with _T. mediocanellata_, these varieties more or less prevail with other species. Thus I have seen them in Tæniæ and Bothriocephali alike. I have obtained segments of _T. mediocanellata_ having sexual outlets on both sides of the proglottis, so regularly disposed in a few segments as to suggest the notion of a new species. The coalescence of several segments into one compound segment is frequent, but the most remarkable specimen that I have seen is one contained in the museum of the Royal College of Surgeons. In the old Hunterian catalogue the specimen is described as “two joints of the _Tænia solium_, with a number of orifices in unequal series on either side.” As stated in the new catalogue of the series, prepared by myself, the “lower segment is furnished with twenty-two sexual orifices, one of which is situated in the central line” on the ventral surface (as in Bothriocephali). References to this and other specimens in the Hunterian Collection will be found below (see _Pittard_). In regard to Weinland’s conjectural _Tænia acanthotrias_, based on the circumstance of his having found a Cysticercus that presented three rows of hooks on its rostellum, I need only say that if such a _Tænia_ were found it would only turn out to be a malformed _T. solium_. The specimens, however, are none the less interesting. Very remarkable and altogether exceptional characters are presented by the strobile of the cestode described by Mr Cullingworth, of Manchester, and of which I possess specimens. Here, apparently, at least two tapeworms are joined together throughout the entire chain of proglottides without intermission. The three margins of each compound segment project at equi-distant angles. Could we have secured the head we should certainly have found six or eight suckers present, since the finest neck-segments showed that the malformation pervaded the entire colony of zooids, sexually mature and otherwise. Mr Cullingworth’s specimen is so remarkable that I subscribe full particulars of the case in his own words. He says:--“A respectable married woman, named Ann H--, forty years of age, residing in Salford, brought to my out-patient room at St Mary’s Hospital, Manchester, on September 3rd, 1873, a few segments of tapeworm as a sample of what she had been passing per anum for about two years. Although never in the habit of taking meat absolutely raw, she told me, on inquiry, that she was particularly fond of tasting it when only partially cooked. The segments were unlike anything I had seen before, and I took them home for examination, ordering the patient meanwhile a draught containing a drachm of the oil of male fern, and giving her strict injunctions to bring to me every fragment that passed away as a result.

“On September 17th she brought me portions of a tapeworm corresponding throughout to the segments I had already seen, and measuring altogether nine feet in length. Unfortunately, the head was not to be found. Along the middle line of every segment in the body a crest or ridge runs longitudinally, and in the centre of the margin of this crest the genital pore is situated. [In 304 segments examined, only four had the genital opening placed laterally. One segment had two openings, viz. one at the lateral margin and the other in the crest.] Underneath the segment there is a longitudinal groove, and the lateral portions are folded together by the apposition of their under surfaces. When hardened in spirit the section of a segment presents a three-branched appearance, the branches being of unequal length, but placed at equal angles. The uterus sends vessels into the crest as well as into the sides of the segment; and the contained ova are exactly like the ova of an ordinary _Tænia mediocanellata_. Wedged in between, or attached to, the segments here and there, is a stunted and ill-shaped joint, with irregular and unequal sides. A mature joint measures from five eighths of an inch to three quarters of an inch in length, and about half an inch in breadth, and the breadth or depth of the crest is usually one eighth of an inch.

“There are only two specimens that I can find on record at all similar to the one here described, and both of these differ from it in several important particulars. Küchenmeister mentions, as a variety of _Tænia mediocanellata_, a tapeworm sent to him from the Cape of Good Hope by Dr Rose. This worm possessed a longitudinal ridge, but he describes its mature segments as ‘extremely massive’--more than an inch in length and 3/5″ in breadth. The genital pores, too, were irregularly alternate, and not situated on the crest. On March 20th, 1866, Dr Cobbold exhibited to the Pathological Society of London a specimen of crested tapeworm which was discovered in the museum of Middlesex Hospital, and to which he proposed to give the name _Tænia lophosoma_ (λόφος, crest; σῶμα, body). The reproductive papillæ were all on one side of the chain of segments, a peculiarity which entirely distinguished it from the Cape of Good Hope variety of Küchenmeister. The head of the creature was wanting. It will thus be seen that my specimen does not correspond with either of these in the situation of the genital aperture. Here it is placed in the crest itself, and not unilaterally, as in Dr Cobbold’s specimen, or alternately, as in Küchenmeister’s. It further differs from the Cape variety in the more moderate dimensions of its proglottides. I have adopted, however, the name suggested by Dr Cobbold in the communication referred to, inasmuch as it sufficiently indicates the principal distinguishing feature of the specimen. I may mention that Dr Cobbold saw the specimen during his visit to Manchester, and that he regarded it as a most remarkable and unique abnormality.”

Further, in connection with abnormal cestodes, I may observe that Weinland’s case of a triple-crowned Cysticercus does not stand alone, since a similar specimen is, I believe, in the possession of the Rev. W. Dallinger. This was removed from the human brain. Curious as this subject is, I cannot dwell upon it. Not only are the mature tapeworms and their Cysticerci liable to present monstrosities, but even also their proscolices or six-hooked embryos. Thus, twelve hooks were observed by Salzmann in the embryo of _T. elliptica_, and Heller also figures two embryos of _T. mediocanellata_ (_T. saginata_, Gœze) with numerous hooklets. Dujardin saw seven in a _Bothriocephalus_ embryo. Occasionally there have been errors of interpretation made by observers. Thus, Diesing has given beautiful figures of _Dibothrium hians_ in such a way as to suggest different degrees of monstrosity affecting the tail end of the strobile; but this splitting has clearly resulted from injury. Thus also, when I removed five specimens of a new cestode (_Diphyllobothrium stemmacephalum_) from the intestines of a porpoise, one of them was cleft nearly half way up the strobile. This had been done by the scissors employed in slitting up the gut; but owing to perfect contraction of the incised edges, it was some time before I discovered that the apparent monstrosity had been artificially produced. Lastly, I may add that many of the older writers were well acquainted with larval and other anomalies. Thus Rudolphi described a two-headed Cysticercus from a Lemur, and also a double-headed _Tænia crassicollis_. This worm had a tripartite body; as had likewise a _Tænia crassicollis_ of which he did not possess the head (_corpore prismatico_). Other monstrosities were described and figured by Bremser and Creplin. Pallas mentions a two-headed Tricuspidaria (_Triænophori nodulosi bicipites_), and, as already stated at p. 97, a double-headed Cysticercus has been obtained from the liver of a sheep.

Before quitting the _Tæniæ_ proper, I may observe that several other species have been indicated, based on ovular and other insufficient characters. To these belong Ransom’s supposed tapeworm, and also Weinland’s _Tænia megaloön_.

BIBLIOGRAPHY (No. 18).--_Bonnet, C._, ‘Œuv. Compl.,’ tom vi, p. 191, 1791.--_Bremser_, Atlas, by Leblond, Pl. iv.--_Chaussat_, ‘Comptes Rendus,’ p. 20, 1850.--_Cobbold_, ‘Catalogue of the specimens of Entozoa in the Museum of the Royal College of Surgeons of England,’ Nos. 118-121, London, 1866.--_Idem_, ‘Worms,’ l. c., p. 78.--_Idem_, “On a Cysticercus from the Human Brain,” ‘Brit. Assoc. Rep.,’ 1870.--_Creplin_, ‘Tænia Monstrum, &c.,’ Berlin, 1839.--_Cullingworth, C. J._, “Notes on a remarkable specimen of Tapeworm (_Tænia lophosoma_, Cobbold),” ‘Med. Times and Gaz.,’ Dec., 1873.--_Davaine_, ‘Les Cestoïdes,’ l. c., p. 570.--_Diesing_, ‘Zwanzig Arten von Cephalocotyleen,’ figs. 1 and 2, taf. ii (aus dem xii, Bd. d. denkschr. d. Math.-nat. Cl. d. k. Akad.), Wien, 1856.--_Dujardin_, l. c., p. 619.--_Heller_, l. c., s. 600.--_Küchenmeister_, l. c., Eng. edit., p. 139.--_Leuckart_, l. c., s. 303 and 465.--_Levacher_, ‘Journ. l’Institut,’ p. 329, 1841.--_Pittard, S. R._, Remarks in his article “Symmetry,” Todd’s ‘Cyclop.,’ vol. iv, p. 848, 1849-52, in which he refers to a monstrous Bothriocephalus (_T. lata_) in the Hunterian Museum, old ‘Catalogue of Nat. Hist.,’ pl. iv, p. 50, No. 205; see also my ‘Catalogue,’ l. c., _supra_, No. 167.--_Ransom_, in Reynolds’ ‘System of Medicine.’--_Rudolphi_, ‘Synops.,’ p. 545 and 598-9, with fig. showing the heads of _Cystic. Simiæ_ (biceps), widely apart, 1819.--_Weinland_ (_T. megaloön_), in Zoolog. Garten, Frankf., 1861, s. 118.--_Idem_, ‘Essay,’ l. c., p. 11.

_Bothriocephalus latus_, Bremser.--This species, though seldom seen in England, is sometimes brought hither by persons who have been residing for a time in foreign countries. It is indigenous in Ireland, and, though by no means common there, has been called the Irish Tapeworm. As regards its distribution in Europe it is much more prevalent in some districts than in others. On this point Leuckart remarks that “foremost amongst these are the cantons of West Switzerland, with the adjacent French districts. In Geneva, according to Odier, almost a fourth part of all the inhabitants suffer from Bothriocephalus. It is also common in the north-western and northern provinces of Russia, in Sweden, and in Poland. In Holland and Belgium it is likewise found, but, on the whole, not so frequently as in the first-named countries. Our German fatherland also harbours them in some districts, especially in eastern Prussia and Pomerania, and there have appeared cases in other places, as in Rhenish Hesse, Hamburg, and even in Berlin; these being apparently spontaneous instances.”

Unlike the ordinary tapeworms, the segments of the broad tapeworm do not individually separate so as to become independent organisms, a circumstance which is highly favorable to the bearer. Its remarkable breadth, and the extremely numerous and closely-packed proglottides, impart a sufficiently distinctive character; but this parasite may be more fully characterised as the largest human cestode at present known, attaining a length of more than twenty-five feet, and sometimes measuring nearly an inch in breadth; the so-called head 1/25″ in width, bluntly pointed at the tip, much elongated or club-shaped, slightly flattened from behind forwards, and furnished with two laterally disposed slit-like fossæ or grooves, but destitute of any armature: anterior or sexually-immature segments of the body extremely narrow, enlarging in a very gradual manner from above downwards; joints of the lower half of the body gradually decreasing in width, but enlarging in depth; sexually-mature segments usually about 1/8 of an inch in depth, but those near the caudal extremity frequently 1/4″, and quadrate in form; body flattened, but not so uniformly as obtains in the ordinary tapeworms, being rather thicker near the central line; total number of joints estimated at nearly 4000, the first sexually-mature ones being somewhere about the six hundredth from the head; reproductive orifices at the central line, towards the upper part of the segment at the ventral aspect, the vaginal aperture being immediately below the male outlet, and both openings surrounded by papillæform eminences; uterus consisting of a single tube, often seen regularly folded upon itself, forming an opaque, conspicuous, centrally-situated rosette; eggs oval, measuring 1/350″ in length by 1/550″ in breadth, having three shell-coverings, and a lid-like operculum at one end, as occurs in the fluke-worms. Owing to the dark color of the egg shells, the uterine rosette is readily seen by the naked eye as a conspicuous deep brown spot at the centre of each successive segment.

The source and development of this parasite are points of considerable interest. The eggs are of comparatively large size, and after expulsion and immersion in water they give passage to beautifully ciliated embryos, which latter produce larvæ furnished with a boring apparatus. These larvæ resemble the six-hooked embryos of other tapeworms. In what animals the larvæ subsequently develop themselves is not ascertained with certainty, but it is probable that persons become infested by eating imperfectly cooked fresh-water fish. Leuckart has suggested that the intermediary bearers are species of the salmon and trout family. Dr Knoch, of Petersburg, thought that there was no need of the intermediate host. He believed that he had succeeded in rearing young broad tapeworms in the intestines of dogs. It was Leuckart who first explained the source of Knoch’s errors of interpretation. Although Knoch administered eggs of _Bothriocephalus latus_ to dogs, and afterwards found young tapeworms of the species in question in the intestines of the dogs, it did not logically follow that any genetic relation (as between the egg-contents and the adult worms) had been thereby established. The circumstance that ripe ova of the Bothriocephalus always contain six-hooked embryos, must alone imply that an intermediate host is necessary for the formation of Cysticerci or measles. If the broad tapeworm could be reared in a direct manner by the administration of Bothriocephalus eggs, there would be no need for the presence of boring hooklets in the proscolex. These are necessary for invading the flesh of some intermediate host.

Dr Fock, of Utrecht, has sent me particulars of an interesting case, and he suggests that infection comes from the little river bleak (_Leuciscus alburnus_). Writing from Utrecht in December, 1877, Dr Fock, after referring to a former case, goes on to say:--“Permettez moi, cher confrère, que je rappelle à votre souvenir que vous avez eu l’obligeance de communiquer au public une observation, de ma main, sur un cas très rare de ver rubanaire, d’un Bothriocephale, chez une petite fille juive. Malheureusement je n’ai pu en donner de plus amples détails, parce que cette enfant n’a plus, depuis ce temps-là, rendu la plus petite parcelle de ver. Il y a maintenant quinze mois, et voilà que de nouveau un cas pareil se présente. Une femme mariée, frisonne, et, cette fois-ci encore, juive, s’est adressée à moi pour la débarasser de son ver. Elle me disait avoir rendu, il y a quelque temps, des fragments, ou plutôt un fragment de la longueur d’un mêtre, d’un ver solitaire, pour lequel elle avait été traitée, sans succès, par son médecin ordinaire. A cause de cela elle s’adressa à moi, et je lui ai repondu qu’elle devrait revenir la première fois qu’elle rendrait de nouveau, spontanément, un nouveau fragment. Après un mois d’intervalle elle est revenue en me montrant un fragment de la longueur d’un demi-mêtre qu’elle venait de rendre spontanément, après avoir jeûni par précepte réligieuse, et deux jours après cela, traitée par l’écorce de grenadier, elle a rendu un Bothriocephale parfaitement conditionné en entier.

“Ce cas me semble assez intéressant pour être communiqué de nouveau, d’abord parce que jusqu’ici personne n’a pu dire par quel chemin a pu s’introduire un tel helminthe, et ensuite parce que ce chemin doit se présenter bien rarement dans nos contrées (ou en Angleterre) puisque dans le courant d’une trentaine d’années ayant rencontré des centaines de tænias, ce cas-ci est seulement le second dont je suis gratifié. Il me semble digne de réflexion que ce cas-ci se présente cette fois-ci de nouveau chez une juive. Est ce cas-ci fortuit, ou bien y-a-t’il un lien de causalité entre ce ver rare et le genre de nourriture ou de boisson de ces bonnes gens? La dame me recontait que, en Frise, il y a un poisson très recherché qui s’appelle en Hollandais blèck, en Anglais blay ou bleak, et dont ils sont très friands, dans lequel, ils rencontrent très souvent un très grand ver rubanaire. Une autre personne me disait avoir été à table chez un ami, qui ne sachant probablement ce qu’il mangeait, savoura avec beaucoup de délice cette friandise dégoutante.”

After describing the specimen, Dr Fock concludes his remarks with a suggestion as to the possibility of introducing tapeworm into the human body by potable water, into which Cysticerci have accidentally found their way. Dr Fock remarks:--“J’ajoute une réflexion par rapport à la provenance des autres tænias, qui jusqu’ici sont introduits par l’usage de la viande non assez cuite ou rôtie, ou saignante; mais, ne se pourrait-il pas que des débris de la chair d’un animal ladre fussent introduits fortuitement dans l’eau, par example, d’un fossé, et que celle-ci employée comme boisson contint des Cysticerques et par ainsi aussi une cause de Tænia? Ce n’est qu’une conjecture que je propose en terminant cet article.”

Although I cannot at all agree with Dr Fock in regarding water as a source of infection in the manner he indicates, yet the still more recently expressed opinions of MM. Bertolus and Duchamp, based on experimental researches, render it tolerably certain that Leuckart’s original surmise was correct, and that we must look to freshwater fishes for the larvæ of the broad tapeworm. In the section of this work devoted to the parasites of fishes I shall make particular allusion to the experiences of Dr Bertolus; but as confirming the view of Leuckart I may here observe, that Bertolus has almost proved that the so-called _Ligula nodosa_ infesting the common trout is merely a sexually incomplete example of _Bothriocephalus latus_. The bleak (_Leuciscus alburnus_) shares with other freshwater fishes the privilege of harbouring a species of _Ligula (L. digramma)_; but whether this form bears any genetic relation to our human _Bothriocephalus latus_ can only be determined by actual experiment. If, as Duchamp and others have either indicated or implied, _Ligula alburni_ is a synonym of the bleak’s cestode in question, then it is evident that the sexually mature form of the _Ligula_ of the bleak is the well-known _L. simplicissima_ of many water birds and of a few other avian species. Probably the bleak-eaters of Holland consume many kinds of freshwater fishes, including various species of the salmon and trout family.

The symptoms occasioned by _Bothriocephalus latus_ do not differ materially from those produced by other tapeworms. According to Odier, as quoted by Davaine, there is not unfrequently a tumid condition of the abdomen, with sickness, giddiness, and various hysterical phenomena occurring at night. Pain in the region of the heart, palpitations, and faintness are also mentioned.

As already hinted, this cestode is very liable to present abnormalities of structure, the proglottides frequently displaying double sexual orifices, with corresponding duplication of the reproductive organs internally. For details respecting the anatomy of _Bothriocephalus_ I must refer to the works of Küchenmeister and Leuckart; and more particularly to the memoir of Drs F. Sömmer and L. Landois, who have supplemented the previous researches of von Siebold, Leuckart, Böttcher, Stieda and others by beautiful investigations of their own. In the pages of ‘Nature,’ for 1872, I gave a _résumé_ of Sömmer’s memoir, which will be found quoted below.

_Bothriocephalus cordatus_, Leuckart.--This species is identical with a worm long ago described by Pallas and Linneus. At present it is only known to infest the residents of North Greenland, but it is probably distributed throughout the north generally. It attains the length of about one foot, and has a small heart-shaped head, whose apex is directed forwards. The neck is so obscure that it may be said to be altogether wanting, the segmentation of the body being well marked immediately below the head. Though so small a species, Leuckart, who first described it, counted between six and seven hundred joints. As in the broad tapeworm, the reproductive orifices are serially disposed along the centre of the ventral line, but a close inspection shows that the folds of the egg-bearing organ are comparatively more numerous. This worm does not appear to be a frequent resident in the human body, though it is by no means uncommon in the dog. Possibly it may yet be found in the inhabitants of some of our northern and western isles.

_Bothriocephalus cristatus_, Davaine.--This cestode measures between nine and ten feet in length, and is characterised by the presence of two remarkable prominences, together forming a sort of rostellum or crest which is covered by numerous minute papillæ. The full-grown segments are less than half an inch in breadth; the body of the parasite being narrower than that of the broad species. The original description of the parasite by Davaine is based on two specimens, one of which, quite perfect, was obtained from a child five years old, under Dr Féréol’s care at Paris. The other was passed spontaneously by an adult residing at Haute-Saône. I have here copied one of Davaine’s original figures of the head of the worm.

BIBLIOGRAPHY (No. 19).--_Bertolus_, “Mém. sur le development du _Dibothrium latum_” (in Appendix to Duchamp’s work, see Bibliog. No. 59).--_Blanchard_, “Recherches, &c.,” ‘Ann. des Sci. Nat.,’ ser. 3, Zool., Pl. 11, 12, 1848.--_Böttcher_, “Studien ueber den Bau des _Both. latus_,” ‘Virchow’s Archiv,’ s. 97 _et seq_, 1864.--_Bremser_, l. c., Bibl. No. 1, s. 88, 1824.--_Chiaje_, ‘Compendio, &c.,’ Tab. iii, figs. 1-5, 1833.--_Cobbold_, ‘Entoz.,’ p. 289, 1864.--_Idem_, “Remarks on the Broad Tapeworm” (with a letter from Dr Fock), the ‘Veterinarian,’ July, 1878.--_Creplin_, in Ersch and Gruber’s ‘Encyclop.,’ 1839, p. 296.--_Davaine_, ‘Traité,’ l. c., 1860; 2nd edit. (_passim_), 1877.--_Idem_, art. ‘Les Cestoïdes,’ l. c., Bibl. No. 2, p. 580-591, 1876.--_Dujardin_, l. c., Bibl. No. 1, p. 612, 1845.--_Eschricht, D. F._, ‘Anat-physiol. Untersuchungen ueber die Bothriocephalen,’ Breslau, 1840.--_Fock_ (see Cobbold).--_Heller_, ‘Darmschmarotzer,’ l. c., s. 606, 1876.--_Knoch_, ‘Petersburger Med. Zeitschrift,’ 1861.--_Idem_, ‘Die Naturgeschichte des breiten Bandwurms (_B. latus_, auct.),’ St Petersburg, 1862.--_Küchenmeister_, ‘Ueber cestoden,’ l. c., 1853.--_Leuckart_, ‘Die Blasen Bandwürmer,’ 1856.--_Idem_, ‘Die mensch. Par.,’ Bd. i, s. 414-448, und 757, 1863; and Bd. ii, s. 866, 1876.--_Owen_, Todd’s ‘Cyclop.,’ 1837.--_Sömmer_ und _Landois_, aus Sieb. und Köll. Zeitschr., ‘Beiträge zur Anatomie der Plattwürmer,’ Leipsig, 1872; see also the _résumé_ in ‘Nature’ for Aug., 1872, p. 278.--_Wawruch_, ‘Pract. Monograph. d. Bandwürm-Krankheit,’ 1844, s. 33.

_Echinococcus hominis_ (the common hydatid).--This larval entozoon has acquired various names according to the kind of bearer in which it happens to have been found; but all the true hydatids or acephalocysts, whether infesting man or animals, are referable to one and the same species of parasite. They have been termed _Echinococcus hominis_, _E. veterinorum_, _E. polymorphus_, _E. exogena_, _E. endogena_, _E. multilocularis_, according to circumstances. All of them represent a juvenile stage of the _Tænia echinococcus_ or hydatid-forming tapeworm which infests the dog and wolf. Experimental proof of this fact has been furnished by Von Siebold (1852), Haubner, Leuckart, Küchenmeister, Van Beneden, Naunyn, Nettleship, Krabbe, and others.

The first successful rearing of _Tæniæ_ with human hydatids was accomplished by Naunyn (1864), his results being subsequently verified by Krabbe and Finsen (1865). Zenker, Ercolani, and several others, including myself, also conducted feeding experiments with human hydatids which were attended with negative results. In the case of one of my experimental dogs the animal was liberated by an ill-disposed person before I had opportunity to destroy it. As the experiment was carefully conducted, the animal may have proved a source of fresh echinococcus-infection. Mr E. Nettleship’s eminently successful experiment was made with hydatids obtained from a sheep. The converse experiment, namely, that of rearing hydatids with the mature proglottides of _Tænia echinococcus_ administered to animals, has been performed most successfully by Leuckart, and by Krabbe and Finsen; by the former in the pig, by the latter in a lamb, with tapeworms that had also been reared by experiment. Zenker, later on, reared the _Tænia_ from hydatids obtained from an ox.

The sexually mature _Tænia echinococcus_ may, for the purposes of diagnosis, be characterised as a remarkably small cestode, seldom reaching the fourth of an inch in length and developing only four segments, including that of the head; cephalic extremity capped by a pointed rostellum, armed with a double crown of comparatively large-rooted hooks, from thirty to forty in number; the four suckers prominent, and succeeded by an elongation of the segment forming the so-called neck; final segment, when sexually mature, equalling in length the three anterior ones; reproductive papilla at the margin of the proglottis rather below the central line; proscolex or embryo giving rise to the formation of large proliferous vesicles, within which the scolices or echinococcus-heads are developed by gemmation.

When an animal is fed with the mature proglottides of _Tænia echinococcus_ the earliest changes that take place are the same as obtain in other cestodes. The segments are digested; the shells of the ova are dissolved; the six-hooked embryos escape. The embryos bore their way into the organs of circulation, and thence they transfer themselves to the different organs of the host; being especially liable to take up their abode in the lungs and liver. Having arrived at this, their resting stage, the embryos are next metamorphosed into hydatids. According to Leuckart’s investigations the juvenile hydatid is spherical at the earliest stages; being surrounded by a capsule of connective tissue formed from the organs of the host. After removal from its capsular covering, the vesicle consists of a thick laminated membrane, forming the so-called cuticular layer, and a central granular mass, which subsequently becomes enveloped by a delicate granular membrane. At the fourth week the echinococcus capsule measures about 1/25″ in diameter, its contained hydatid being little more than half this size. Its future growth is by no means rapid, seeing that at the eighth week the hydatid has attained only the 1/15″ in diameter. At this period the central granular mass develops a number of nucleated cells on the inner surface of the so-called cuticle. These cells, which at first are rounded or oval, become angular or elongated in various directions, and even distinctly stellate; and in this way a new membrane is formed, constituting the so-called inner membrane or granular layer. The intermediate stages between this condition and that of the fully-formed echinococcus hydatid have not been satisfactorily traced in detail; nevertheless, Krabbe and Finsen’s experiment on a lamb showed that within a period of little more than three months well-developed echinococcus-heads may be formed in the interior of the vesicles. It is thus clear that the production of scolices immediately follows the formation of the granular layer, and this is succeeded, though not invariably, by the formation of daughter- and grand-daughter-vesicles, which are sometimes termed “nurses.” These latter may be developed exogenously or endogenously.

The appearance of hydatids varies very much according to their mode of formation, to the kind of host in which they are present, and to the character of the organs in which they happen to take up their residence. The so-called exogenous type occurs sparingly in man, whilst the endogenous type is very abundant. The peculiar form known as the multilocular echinococcus is probably a mere variety of the exogenous type. The exogenous and endogenous hydatids may coexist in the same bearer. In the lower animals we commonly find the organs of the body occupied by numerous lobulated cysts, varying in size from a walnut to a goose’s egg, but sometimes rather larger. They are rarely solitary, being particularly liable to occupy both the liver and lungs in the same animal. The viscera are sometimes crowded with cysts. The hydatids do not usually protrude much beyond the surface of the infested organ, but lie imbedded within its parenchymatous substance.

The multilocular variety was first described by Virchow. In reference to it Leuckart writes as follows:

“Hitherto we know this growth only from the liver, in which it forms a firm, solid, and tolerably rounded mass of the size of the fist or even of a child’s head. At first sight it looks more like a pseudoplasm than a living animal parasite. If you cut through the tumour, you recognise in its interior numerous small caverns, mostly of irregular shape, and separated from one another by bundles of connective tissue, more or less thick, and including a tolerably transparent jelly-like substance. In the intervening stroma a blood-vessel or a collapsed bile-duct runs here and there; but there is nowhere any trace of true liver substance. The outer boundaries of the tumour are in most cases pretty well defined, so that the attempt to cut these growths out is not difficult. In particular spots, especially at the surface, one sometimes sees white, moniliform, jointed lines passing off from the tumour, and even thicker terminations which, perhaps, expand in the neighbouring liver-parenchyme into new (multilocular) groups of different size. In one case, recorded by Virchow, the growth extended, together with Glisson’s capsule, a long way towards the intestine.” To this description it may be added, that the growth on section presents an appearance not altogether unlike alveolar colloid, having, in point of fact, been confounded with that pathological product, with which, however, as stated by Virchow, it has nothing in common. This is proved not only by the occurrence of the pathological features above mentioned, but also, more particularly, by the well-ascertained presence of echinococcus-heads in most of the so-called alveoli. Several hypotheses have been broached with the view of explaining the mode in which these multilocular hydatid growths are formed. Virchow thought that the echinococcus vesicles were primarily formed in the lymphatic vessels, whilst Schröder van der Kolk supposed that they originally took up their abode in the biliary ducts. Although, thanks to the courtesy of Professor Arnold Heller in giving me a specimen, I have been enabled to confirm much that has been written in respect of the morbid appearances, I can add nothing towards the solution of the difficulty in question. Until lately it was supposed that the multilocular variety of hydatids only existed in man, but Professor Böllinger has encountered it in the liver of a calf.

Selecting any ordinary fresh example of the exogenous kind, and laying the tumour open with a scalpel, we notice in the first instance an escape of a clear transparent, amber-coloured fluid. This previously caused the distension of the sac. If the tumour is large, this escape will probably be followed by a falling in, as it were, of the gelatiniform hydatid membrane, in which case the inner wall of the external adventitious investment or true fibrous cyst will be laid bare. If the hydatid be next withdrawn from the cyst, it will be seen to display a peculiar tremulous motion, at the same time coiling upon itself wherever there is a free-cut margin. Further examination of portions of the hydatid will show that we have two distinct membranes; an outer, thick, laminated, homogeneous elastic layer (the _ectocyst_ of Huxley), and an internal, thin, soft, granulated, comparatively inelastic layer--the _endocyst_ of the same author. The terms are convenient. The ectocyst is structureless, consisting of a substance closely allied to chitine. For this and other reasons it has been called the cuticular layer, but the endocyst is the essential vital part of the animal, representing a huge compound caudal vesicle. In an hydatid from the zebra, Huxley found that the endocyst was “not more than 1/2000th of an inch in thickness, being composed of very delicate cells of 1/2000″ to 1/5000″ in diameter, without obvious nuclei; but often containing clear, strongly refracting corpuscles, generally a single one only in a cell.” Prof. Huxley adds: “These corpuscles appear to be solid, but by the action of dilute acetic acid the interior generally clears up very rapidly, and a hollow vesicle is left of the same size as the original corpuscle. No gas is developed during this process, and sometimes the corpuscles are not acted upon at all by the acid, appearing then to be of a fatty nature. A strong solution of caustic ammonia produces a concentrically laminated or fissured appearance in them. Under pressure and with commencing putrefaction a number of them sometimes flow together into an irregular or rounded mass.”

The precise mode of development of the echinococcus-heads or scolices has been a subject of lengthened discussion between Leuckart and Naunyn. According to Leuckart the earliest indication of the scolex consists of a slight papillary eminence on the inner surface of the granular endocyst. After a short period this prominence displays in its interior a vacuole-like cavity, the latter being occupied, however, with a clear limpid fluid. Its margins become more and more clearly defined, until the cavity is by and by seen to be lined with a distinct cuticular membrane. The papilla increasing in size, becomes at first elongated or oval, eventually scoleciform, or even, perhaps, a true echinococcus-head. Thus far the description bears out, in a measure, the theoretical notions entertained by the older authors; but the developmental process does not stop here. The scolex-development has now to sacrifice itself by developing in its interior a brood of scolices or echinococcus-heads. In other words, it becomes transformed into the so-called brood-capsules of Leuckart and other authors. These structures were previously well known to Professors Erasmus Wilson and George Busk. Mr Wilson spoke of the capsule as “_a delicately thin proper membrane_, by which the Echinococci are connected with the internal membrane of the acephalocyst” (‘Med.-Chir. Trans.,’ 1845, vol. xxviii, p. 21). Mr Busk described the echinococcus-heads as “attached to a common central mass by short pedicles, which appear to be composed of a substance more coarsely granular, by far, than that of which the laminæ of the cyst are formed. This granular matter is prolonged beyond the mass of Echinococci into a short pedicle common to the whole, and by which the granulation is attached to the interior of the hydatid cyst.” What Mr Busk here describes as a granulation can only be equivalent to the brood-capsule and its entire contents, but he elsewhere speaks of the capsule itself as a “delicate membranous envelope.” It should be borne in mind that Busk’s paper was communicated to the Microscopical Society so early as the 13th Nov., 1844; being published in the ‘Transactions’ for that year.

In the completely developed state the echinococcus-heads exhibit somewhat variable characters as to size and form, the latter differences being, for the most part, dependent upon their degree of contraction and vitality. In the perfect condition they vary from the 1/60″ to the 1/100″ in diameter, being usually about the 1/80″. They are solid, and when stretched out exhibit an hour-glass-like constriction at the centre of the body, which divides the scolex into an anterior part supporting the rostellum and suckers, and a posterior part which has been compared to the caudal vesicle of ordinary Cysticerci. The rostellum supports a double crown of hooks, but the disparity of the two series is scarcely sufficiently marked to render their distinction obvious. The hooks of the smaller row vary in size from 1/1040″ to 1/830″ of an inch, whilst those of the larger series are from 1/830 to 1/555″. In all instances the root-processes are incompletely developed, and consequently vary in thickness. They are, as Leuckart also has stated, apt to exhibit abnormalities.

In regard to the development of the echinococcus-heads it further remains for me to observe that a distinct water-vascular system is recognisable in the scolices. By the intervention of the pedicle of the scolex this system is connected with the brood-capsule, and also with the vessels of the maternal endocyst. In the scolex there exists a circular channel immediately below the rostellum, and this ring, on either side, gives off two vessels which pass downwards in a tortuous manner, internally, until they arrive at the pedicle where they unite to form two channels, which latter are continued into the vascular system of the maternal endocyst. In the retracted condition their position, of course, becomes very much altered, and they form loops on either side of the central line which marks the space leading down to the inverted head. Neither Prof. Huxley nor myself have seen these vessels, which Leuckart observed in the scolex itself, but Huxley discerned some apparently loose cilia in the granular parenchyma of the body; their longitudinal measurement being about the 1/3500 of an inch.

As regards the production of “nurses” by the phenomenon of proliferation, I can only remark that the endocyst is primarily concerned. The secondary and tertiary vesicles must be regarded as so many special bud-developments which, instead of becoming brood-capsules, become daughter-vesicles and grand-daughter vesicles, constantly developing in their interior secondary and tertiary brood-capsules and scolices, but sometimes, it would appear, developing neither the one nor the other. This is the view of Naunyn, which is somewhat opposed by Leuckart, who holds that the vesicles ordinarily arise from within the layers of the ectocyst. Speaking of these daughter-hydatids Leuckart remarks that “Naunyn denies that they take their origin between the lamellæ of the mother bladder--a fact, however, which, in agreement with Kuhl and Davaine, I have seen more than once and have followed out step by step.” For my own part I incline to the belief that the process as observed by Leuckart is exceptional, and that under ordinary circumstances it occurs as Naunyn has described it. Thus the long and short of the whole matter appears to be that the endocyst is capable of forming solitary scolices. Some of the scolices become differentiated to form brood-capsules, a portion of whose individual echinococcus-heads may, in their turn, become secondary brood-capsules, whilst others fail to become either scolices or brood-capsules. It accords with our knowledge of the general plan of development to believe that the daughter and grand-daughter hydatids are likewise peculiarly modified scolices. They are, in short, buds of the endocyst.

The distribution of hydatids throughout the organs of the bearer, and their prevalence in particular countries, has especially engaged my attention. I have personally examined upwards of a thousand preparations of entozoa in our public collections; and of these, 788 are preserved in the anatomical and pathological museums of the metropolis. By this inspection I have obtained a tolerably accurate knowledge of the pathology, localisation and effects produced by the presence of bladder-worms in at least 200 unpublished cases of hydatid disease. Most of our museums exhibit one or more specimens that are unique. After making certain necessary deductions, I find that I have 192 new cases to add to the 135 cases of hydatid disease that I had previously recorded, affording a total of 327 cases available for statistical purposes. If an analysis of these cases be made and compared with the statistics furnished by Davaine, and if the whole be reduced to the lowest number of practically available terms, we at length obtain a result which, although it may be only approximatively correct, is nevertheless of much practical value and significance. The statistics in question stand as follows:

+-----------------------------+----------+-----------+--------+ | Organs affected. | Davaine. | Cobbold. | Total. | +-----------------------------+----------+-----------+--------+ | Liver | 165 | 161 | 326 | | Abdomen, including spleen | 26 | 45 | 71 | | Lungs | 40 | 22 | 62 | | Kidney and bladder | 30 | 23 | 53 | | Brain | 20 | 22 | 42 | | Bones | 17 | 16 | 33 | | Heart and pulmonary vessels | 12 | 13 | 25 | | Miscellaneous | 63 | 25 | 88 | +-----------------------------+----------+-----------+--------+ | Total | 373 | 327 | 700 | +-----------------------------+----------+-----------+--------+

In the main Davaine’s table and my own show a remarkable correspondency, as is seen in the numbers referring to hydatids of the liver, heart, and bones respectively. Where our results do not correspond the explanation of the discrepancy is sufficiently simple. The abdominal cases here credited as such in Davaine’s table are placed by him under _pelvis_, whilst the abdominal cases in my own table not only include the pelvic hydatids, but also two _spleen_ cases, and nineteen others from the peritoneum and intestines.

As the facts here stand, the liver cases comprise nearly 46-1/2 per cent. In a large number of cases the entozoon has taken up its abode in organs of vital importance. If statisticians and officers of health would obtain an adequate conception of the fatal capabilities of parasites, they should consider these data. In 6 per cent. of all these cases the bladder worm has found its way into the brain, and of course proved fatal to the bearers; in about 3-1/2 per cent. more they took up their residence in the heart, also proving fatal; whilst of all the other cases put together I reckon that not less than 15 per cent. were concerned in bringing about the death of their hosts. I probably underrate the fatal capabilities of echinococcus disease when I express the conviction that hydatids prove fatal to 25 per cent. of all their human victims.

The recently published analysis of 983 cases by Dr Albert Neisser affords similar results. Of these, 451 were referable to the liver, or 45·765 per cent. The other cases, reduced as above, show in the main a similar correspondency.

It may be asked if these facts afford us any assistance in determining the amount of injury that we, as a people, sustain either directly or indirectly from hydatids. On carefully reviewing all the data before me, I may say that it is difficult to draw very precise conclusions; albeit it is not mere guess-work when I assert that in the United Kingdom several hundred human deaths occur annually from this cause. In some other countries the proportion is far greater; the oft-quoted case of Iceland, where the disorder is fatally endemic, still standing at the head of the afflicted territories.

Our Australian colonies are probably entitled to the next place of distinction in this respect. We have strong and recent evidence of the truth of this statement. Thus a writer in the ‘Australian Med. and Surg. Review’ says: “This disease is becoming unpleasantly frequent, and at present we have no reliable mode of treatment, either theoretical or empirical.” Another writer observes (‘Melbourne Argus,’ May 18th, 1874), “Hydatid disease is endemic in this colony; and, though not so constantly met with as in Iceland, we may probably claim the doubtful honor of holding the second place in the list of countries so affected.” In the ‘Argus’ for June 20th of the same year, another writer refers to the frequent notices of cases of hydatids published in the various local newspapers. A retired medical man, the late Mr J. P. Rowe, writing in the ‘Melbourne Leader’ (Sept. 7th, 1872), incidentally remarked on the “notable increase of hydatid disease in the human subject.” Again, still more satisfactory evidence is afforded by a reviewer in the ‘Leader’ of the 31st January, 1874. Commenting on my manual, he not only takes occasion to speak of the prevalence of hydatids generally, but also supplies that kind of accurate statistical evidence of which we so much stand in need. He gives the following table, showing the number of _deaths_ from hydatids in Victoria for eleven years. It is instructive in many ways.

+------------------------------+--------+----------+--------+ | Years. | Males. | Females. | Total. | +------------------------------+-------------------+--------+ | 1862 | 3 | 2 | 5 | | 1863 | 3 | 2 | 5 | | 1864 | 6 | 3 | 9 | | 1865 | 9 | 6 | 15 | | 1866 | 18 | 7 | 25 | | 1867 | 13 | 12 | 25 | | 1868 | 21 | 12 | 33 | | 1869 | 12 | 10 | 22 | | 1870 | 10 | 7 | 17 | | 1871 | 6 | 9 | 15 | | 1872 | 24 | 5 | 29 | +------------------------------+-------------------+--------+ | Total deaths in eleven years | 125 | 75 | 200 | +------------------------------+--------+----------+--------+

To employ the writer’s own words, “this mortality gives only a faint notion of the extreme prevalence of hydatids in Victoria, since numbers of cases are cured by tapping, and otherwise by medical treatment, or by spontaneous bursting of the cysts.” Hydatids are often found post mortem where their presence has never been suspected during life. “To meet with hydatids as a cause of deranged health is now a matter of daily expectation with every medical practitioner.” Lastly, Dr Dougan Bird, in his able brochure on ‘Hydatids of the Lung,’ fully confirms these statements, remarking that the rich and poor of the Australian metropolis suffer just as much from hydatids as do either the shepherds of the western plains, or the miners of Ballarat and Sandhurst.

Such are the facts from Australia. As regards home evidence, so far as I am aware, little or nothing has been done towards securing an accurate estimate of the mortality in England from echinococcus disease. The reports of the Registrar General give no sufficient sign. The explanation is not far to seek, since for the most part hydatids are either classed with diseases of the liver, or with those of the other organs in which they happen to have been present.

One of the most valuable contributions to our knowledge of the prevalence of hydatid disease affecting animals is that supplied by Dr Cleghorn, from a statistical table constructed by the executive commissariat officers stationed at Mooltan. The record in question shows that out of 2109 slaughtered animals, no fewer than 899 were affected with hydatid disease. This is equal to more than forty-two per cent. In the majority of cases, both the lungs and liver were affected, cysts were found 829 times in the liver and 726 times in the lungs. In a few instances they were present in the kidneys, and also occasionally in the spleen. The inference from all this is that in India, if not elsewhere, the echinococcus disease is much less common in man than it is in animals. The explanation is simple enough, since cattle have more ready access to, and less scruple in partaking of filthy water and food in or upon which the eggs of the _Tænia echinococcus_ abound.

Into purely professional questions connected with the treatment of the echinococcus malady I do not here enter; nevertheless, in connection with hygiene I may observe that the prevalence of hydatids in any country is strictly dependent upon the habits of the people. The close intimacy subsisting between the peasantry and their canine companions is the primary source of the endemic; and where dogs are not kept, it is well nigh impossible that the disease should be contracted. The fact that every Icelandic peasant possesses, on an average, six dogs, and that these dogs share the same dwelling (eating off the same plates and enjoying many other privileges of intimate relationship) sufficiently explains the frequency of hydatids in that country. According to Krabbe, the sexually mature _Tæniæ_ occur in 28 p. c. of Icelandic dogs, whereas in Copenhagen he found it twice only in 500 dogs examined. In his work (quoted below, p. 58, or Fr. Edit., p. 60) Krabbe comments on a sensational passage which, in my introductory treatise (p. 283), I had quoted from a popular memoir by Leuckart (‘Unsere Zeit,’ s. 654, 1862). The practitioners whom we had spoken of as “quacks” are mostly homœopaths; and it appears that even those who are not in any legal sense professional men “treat their patients much in the same way as ordinary medical men.” It simply comes to this, that, instead of _dog’s excrement_ forming with the aforesaid “quacks” a conspicuous or common remedy (as Leuckart’s description had led me to infer), this nasty drug is now rarely administered, and by the grossly ignorant only.

Up to the present time no person has seen the _Tænia echinococcus_ in any English dog which has not been previously made the subject of experiment, but considering the prevalence of hydatid disease amongst us, there can be no doubt that English dogs are quite as much if not more infested than continental ones. Probably, at least one per cent. of our dogs harbour the mature tapeworm. Certainly a great deal of good might accrue from the acquisition of more extended evidence respecting the prevalence of this and other forms of entozoa infesting man and animals in this country.

From Schleissner’s table it appears that hydatids are more frequent in women than in men. Apparently, it is not so in Australia. As regards Iceland the explanation must be sought for in the different habits of life. No doubt, water used as drink by women is constantly obtained from supplies in the immediate neighbourhood of dwellings, and in localities to which dogs have continual access. The comparative rarity of the echinococcus disease amongst sailors is not so much dependent upon the circumstance that seamen’s diet usually consists of salted provisions, as upon the fact that these men can seldom have opportunities of procuring water from localities where dogs abound. In regard to water drinking, there is ground for believing that the addition of a very little alcohol is sufficient to destroy the six-hooked embryos of _Tænia echinococcus_ whilst still _in ovo_; and there is no doubt that water raised to a temperature of 212° Fahr. will always ensure the destruction of the larvæ. Boiled water by itself is by no means palatable. The reason why the upper classes comparatively seldom suffer from hydatids may be attributed to the circumstance that those few who drink water take the very proper precaution to see that it is either “pump” or fresh spring water in which no living six-hooked embryos are likely to exist. So far as hydatids are concerned, wine and beer drinking is preferable to water-drinking; yet if water is carefully filtered no evil of the parasitic kind can possibly result from its imbibition. An ordinary charcoal filter will effectually prevent the passage of the ova, since their diameter is nearly 1/370 of an inch.

From what has been stated it follows that personal and general cleanliness are eminently serviceable as preventions against infection, but to ensure perfect success other precautions must be exercised, especially in relation to our contact with and management of dogs. Leuckart puts this very clearly when he says:--“In order to escape the dangers of infection, the dog must be watched, not only within the house, but whilst he is outside of it. He must not be allowed to visit either slaughter-houses or knackeries, and care must be taken that neither the offals nor hydatids found in such places are accessible to him. In this matter the sanitary inspector has many important duties to perform. The carelessness with which these offals have hitherto been disposed of, or even purposely given to the dog, must no longer be permitted if the welfare of the digestive organs of mankind is to be considered. What blessed results may follow from these precautions may be readily gathered from the consideration of the fact that, at the present time, almost the sixth part of all the inhabitants annually dying in Iceland fall victims to the echinococcus epidemic” (l. c., s. 654). Similar measures had previously been recommended in less explicit terms by Küchenmeister, who in effect remarked that the principal thing was to ensure the destruction of the echinococcus vesicles. He also recommended the expulsion and annihilation of the _Tænia echinococcus_. In order to carry out this idea, it was suggested by Dr Leared that every dog should be periodically physicked, and that all the excreta, tapeworms included, should be buried at a considerable depth in the soil. I advised, however, that in place of burying the excreta, _they should, in all cases, be burnt._ I had, indeed, long previously urged this measure (in a paper “on the _Sclerostoma_ causing the gape-disease of fowls,” published in 1861), with the view of lessening the prevalence of entozoa in general, whether of man or animals. The rule I suggested stood as follows:--_All entozoa which are not preserved for scientific investigation or experiment should be thoroughly destroyed by fire, when practicable, and under no circumstances whatever should they be thrown aside as harmless refuse._ As an additional security I recommended that boiling hot water be occasionally thrown over the floor of all kennels where dogs are kept. In this way not only would the escaped tapeworms be effectually destroyed, but also their eggs and egg-contents, including the six-hooked embryos. These measures were again advocated at the Cambridge Meeting of the British Association in 1862, and also more fully in a paper communicated to the Zoological Society, during the autumn of the same year (‘Proceedings,’ vol. xxx, pt. 3, pp. 288, 315).

As the scope and tendency of this work preclude the textual admission of clinical details, I must limit my remaining observations to the pathology of hydatid disease. At very great labor, pursued at distant intervals during a period of ten years, I sought to ascertain the probable extent and fatality of this form of parasitism in England, by going over such evidence as our pathological museums might supply. Although, from a statistical point of view, the investigation could hardly be expected to yield any very striking results; yet clinically viewed the study was most instructive. The evidence which I thus procured of numerous slow and painful deaths from echinococcus disease, further stimulated me to place a summary of the facts on record. Physicians, surgeons, scientific pathologists, and veterinary practitioners are alike interested in the study of hydatid disease; and I had not proceeded far in my careful investigation before it became evident to me that very great practical results would ensue if, in this kind of effort, the principle of division of labor had full play. At all events, within these museums lie concealed a mass of pathological data which, although well within reach, have not been utilised to the extent they ought to have been.

As a student of parasites for some thirty years, I must without offence be permitted to protest against the too frequent omission of parasites in statistical evidence as a cause of mortality. From facts within my own knowledge I can confidently assert that parasites in general, and hydatids in particular, play a far more important part in the production of disease and death than is commonly supposed. In saying thus much, however, I am not insensible to the fact that, in recent times, new methods of treatment combined with higher surgical skill, have greatly tended to lessen the fatality of this affection. In this connection I would especially refer to the recorded experiences of an able colonial surgeon, Dr MacGillivray, as made known in the pages of the ‘Australian Medical Journal.’ The able surgeon to the Bendigo Hospital, treated as in-patients, from 1862 to 1872, inclusive, no fewer than seventy-four cases of hydatid disease. He operated on fifty-eight of them. Two patients were tapped for temporary relief (as they were dying of other diseases); and of the remaining fifty-six only eleven died. No fewer than forty-five were discharged _cured_--a fact redounding largely, I should think, to the credit of Australian surgery.

In reference to museum evidence I have no hesitation in saying that the pathological collections in the metropolis abound in rare and remarkable illustrations of hydatid disease; most of the preparations being practically known only to such few members of the medical profession as have been at some time or other officially connected with the museums. Not without justice, curators often complain that their work and catalogues are turned to little account. As a former conservator of the Edinburgh University Anatomical Museum (1851-56), and subsequently as museum-curator at the Middlesex Hospital Medical College, I am in a position to sympathise with them. Valuable, however, as the catalogues are, it is often necessary to make a close inspection of the preparations in order to arrive at a correct interpretation of the facts presented.

Although the entozoal preparations in the museum attached to St Bartholomew’s Hospital are, comparatively speaking, few in number, there are some choice specimens of hydatid disease. There is a remarkable case in which hydatids invaded the right half of the bones of the pelvis; death resulting from suppurative inflammation of the cysts. This patient, a woman, had also another hydatid cyst which was connected with the ovary. Amongst the series contributed by Dr Farre, there is a case represented where a large cyst containing numerous hydatids “occupied the pelvis of an infant and produced retention of urine,” which ultimately proved fatal. There are also several fine examples of hydatids from the omentum (Dr Farre’s case), besides a good specimen of acephalocysts connected with the vesiculæ seminales. There are two other cases in which these larval entozoa were passed with the urine. At the time when I made my inspection, the entire series represented twenty-five separate cases, of which only one appears to have been published in detail (Mr Evans’s case, ‘Medico-Chirurgical Transactions,’ 1832). In addition to the above, I must not omit to particularise two instructive preparations illustrative of a case in which an hydatid was lodged in the right half of the cerebrum. This was from a girl in whom head symptoms showed themselves a year before death, and in whom there was partial hemiplegia of the left side. I may add that there is also in the series a doubtfully genuine example of hydatids of the breast.

The collection in connection with the Westminster Hospital contains several highly interesting specimens of entozoa (one of which I believe to be altogether unique), but it is by no means rich in the matter of hydatids. Out of a score of preparations of parasites of various kinds, only four (apparently representing the same number of cases) are hydatids, all of which appear to have been connected with the liver. Two are certainly so, one of the latter (Mr Holthouse’s case) showing calcareous degeneration.

The museum connected with St Mary’s Hospital Medical School, in addition to several liver cases, contains one interesting example of hydatids of the lung (Dr Chambers’s case), and also three valuable preparations illustrating Mr Coulson’s remarkable case of hydatids affecting the tibia. One of the preparations shows the bone itself, which was eventually removed at the joint, the operation having been performed by Mr Spencer Wells.

Here, perhaps, it will not be out of place to mention as a fact of special clinical interest that I have encountered records of no fewer than nine other similar cases where hydatids have taken up their abode in the tibia, generally selecting the head or upper part of the bone. Some of my notes have been mislaid, but, speaking from recollection, one of the choicest specimens which I have examined is that contained in the pathological museum of the Nottingham Hospital.

When I first went over the collection of the Middlesex Hospital Museum, I found it to contain fifty-four preparations of entozoa, of which some fourteen only were true hydatids, representing as many separate cases. There are now upwards of a score of preparations of hydatids, several of the cases having already had ample justice done to them by Dr Murchison in his well-known memoir (‘Edinb. Med. Journ.,’ Dec., 1865). Amongst the most interesting preparations I would especially call attention to two fine and genuine specimens from the kidney, another very large example of an hydatid situated between the bladder and rectum, a simple acephalocyst removed from the orbit (Mr Hulke’s case), and the hydatid removed from the axilla by the late Mr Charles Moore. There is a jar containing hundreds of hydatids that were taken from the thoracic cavity of a dissecting-room subject, who was reported to have died of phthisis; and there is another preparation of an hydatid of the heart, which also proved fatal, without there having been the slightest suspicion entertained as to the true nature of the disease. For this fine preparation the museum stands indebted to Dr Moxon, of Guy’s Hospital. Several of the liver cases are particularly instructive; but amongst the specimens presented by Mr Mitchell Henry is a small bottle full of minute hydatid vesicles, all of which were removed from the interior of the tibia. The history of this case has been lost; and, unfortunately, the bone from which the parasites were taken does not appear to have been preserved.

The museum connected with King’s College contains at least a dozen good specimens of liver hydatids, several of the cases being of special interest from a pathological point of view. There are two remarkably fine examples of hydatids contributed by Dr Hooper, the parasites in one case affecting the spleen, and in the other involving the ovary and uterus. The spleen contained numerous encysted hydatids, whilst the uterine organs exhibited “an immense collection” of the same growths. In this place, also, I may refer to an hydatid-like entozoon, taken from a cyst in the ovary of a female who had been under the care of Dr Johnson (1860). It is, apparently, a genuine example of the slender-necked hydatid (_Cysticercus tenuicollis_); and if so (as might be determined by dissection), is, so far as I aware, the only specimen of the kind in existence from the human bearer. There is a renal hydatid (presented by Dr Pass, of Warwick) which was obtained from a lunatic, its presence being “quite unsuspected during life.” Amongst the liver cases (the majority of which are from Dr Hooper’s collection), there is one enormous hydatid that was obtained from a young woman who had died during a fit of laughter. The tumour had pushed the diaphragm up to a level with the fourth rib; and it is stated that, on puncturing the cyst, the fluid contents were ejected “in a jet nearly two feet high.” There is one case represented where numerous hydatids were expectorated after hepatitis, whence it was concluded that they were originally connected with the liver. There is a large solitary hydatid that was removed from a young female who died of phthisis, and in whom the consequent swelling had formed in the neighbourhood of the navel. Especially instructive, also, from a clinical point of view, is a case of peritoneal hydatids where the tumours had been diagnosed to represent a case of extra-uterine fœtation. It appears that there were two cysts, one of them being connected with the uterus. Two of the enormous hydatids taken from these cysts are preserved in the collection of the Anatomy School of Oxford. Several of the preparations show to perfection the stages of natural cure produced by calcareous degeneration; and there is one liver showing three of these so-called ossified cysts. The disease in this case proved fatal.

Most of the entozoa displayed in the Charing Cross Hospital Museum have been contributed by Dr Wiltshire, the series being particularly strong in tapeworms. There are four characteristic examples of hydatids of the liver, representing as many separate cases. Two were from abscesses of this organ. In one of these, Mr Canton’s case, the hydatid was, I believe, expelled after operation; but in the other example (presented by Mr Rose, of Swaffham) the parasite was evacuated from an abscess, which burst of itself, externally.

In the museum at University College, I examined sixteen preparations of hydatid disease, representing almost as many distinct cases. One is a wax model. Eight of the specimens were from the liver, five from the abdomen (including those of the omentum and mesentery), two from the lungs, and one from the heart. The model displayed ordinary hydatids of the liver bursting into the lungs. The mesenteric example is particularly fine, whilst that from the omentum is undergoing calcareous degeneration. Probably the most interesting of all is the example showing an hydatid lodged in the septum of the heart. This was from a middle-aged female, who died suddenly whilst pursuing her ordinary domestic avocations.

The museum of the Royal College of Surgeons contains a fine collection of parasites, its chief strength in this respect being due to the special series of entozoa. Were visitors to judge by the contents of the catalogue of this series (which I prepared some years ago at the instance of the Council of the College), they might be led to suppose that the hydatids were only feebly represented. Out of nine preparations of hydatids in this section, only six have come from the human body. However, scattered throughout the collection, I found that there were no fewer than thirty-five preparations of hydatids belonging, apparently, to as many as thirty separate cases. Omitting, for the present, all mention of these derived from animals, I ascertained that, of the thirty human cases, thirteen were referable to the liver, four to the abdomen, three to the lungs (one of which was originally connected with the liver), and two to the brain. Five were of uncertain seat. With the abdominal cases we may also include one case of hydatids of the spleen, and another where these organisms were found in the region of the bladder. There is a characteristic breast case. One of the original Hunterian cases (in which “a prodigious number of hydatids were found in the sac of the liver and dispersed throughout the cavity of the abdomen”) appears, though it is not expressly so stated in the catalogue, to have been regarded as an ordinary example of abdominal dropsy. In one of the three lung cases two small hydatids were separately expectorated at an interval of about a month. This occurred in a female.

I may here incidentally remark that many cases are on record where abdominal hydatids have been overlooked, the patient being supposed to be suffering from ascites. One such instance took place a few years ago at the Middlesex Hospital. I well remember a similar case of supposed hydrothorax, where the post-mortem examination revealed the presence of immense numbers of these formations occupying the right side of the chest. This case occurred at the Norfolk and Norwich Hospital, at the time when I was a student there, some thirty-five years ago.

The pathological collection connected with St George’s Hospital displays several good hydatid preparations, the entire series representing at least twenty-two separate cases. Of these, fifteen are referable to the liver, that is, if we include Dr Dickinson’s case, already published, where hydatids were found within the hepatic duct. There are two renal cases; also one from the brain (Dr Dickinson’s case), and another where an hydatid was expectorated. Besides these, there are three other highly characteristic examples of echinococcus disease affecting the region of the neck, breast, and axilla respectively.

The museum of the London Hospital Medical School contains a large collection of parasites. Out of fifty-seven preparations of entozoa, I found twenty-two referable to hydatids; and, so far as I could gather, all of them belonged to different cases. Only one case seems to have been published in detail. This, though a very old preparation, is a fine example of an hydatid, nearly three inches in length, occupying one of the cerebral hemispheres (‘Edinb. Med. Journ.,’ vol. xv). There is a second brain case, where the vesicles were of small size, but very numerous. Of the other twenty cases, fourteen belong to the liver, two to the spleen, one to the lung, one to the uterus; one being a very large hydatid of doubtful seat, and another being referable to the lumbar region, where it formed a tumour containing “a large number of small hydatids.” Amongst the more remarkable specimens is that described in the MS. catalogue as “a true hydatid cyst developed in connection with the broad ligament.” This preparation, unique of its kind, shows no trace of the ovary, which, indeed, seems to have disappeared altogether. One of the liver cases should rather be classed as abdominal, since the large cyst is situated between the diaphragm and liver, pressing upon the latter organ below and also upon the lung above, but apparently not involving either of these viscera structurally. Another very striking case is that in which there is an external opening communicating with the cyst in the liver, and an internal opening through the diaphragm communicating with the lungs and bronchial tubes. The patient had actually coughed up liver hydatids by the mouth, and had passed others through the right wall of his abdomen. There is another liver case in which the hydatids, in place of escaping externally, had gained access to the inferior cava; and if I understand the MS. record rightly, in the same patient a second hydatid communicated with the portal vein, and a third with the hepatic vein. Lastly, I must add that there is yet another fine preparation of liver hydatids, occurring in a lad, nineteen years of age. He had, it seems, met with “a slight accident, and died with obscure head symptoms;” but the odd part of the case is that at the post-mortem examination there was positively nothing found that could explain the patient’s death. He was under the care of Mr Luke (1834).

Comparatively recently I inspected the collection at St Thomas’s Hospital, which I found to be particularly rich in entozoa of various kinds, especially tapeworms and hydatids. I encountered seventy-six preparations of internal parasites; and of these, forty-two were of the hydatid kind, representing at least thirty-three different cases. I say “at least,” because it is often impossible to decide in instances where no history of the specimens can be obtained. Thus, there are three similar preparations of hydatids passed by the urethra, and, from their appearance, I judge them to have come from one and the same patient; yet there is no statement in the catalogue to that effect.

Of the thirty-three cases of hydatids represented in this museum, I reckoned eighteen as referable to the liver, two to the brain, two to the bones, two to the urinary organs, and one to the lung, spleen, uterus, and soft parts of the thigh respectively. There are also three that may be classed as peritoneal. There is another choice example in which the disease cannot be referred to any particular organ. I allude to Dr Peacock’s case, already published (‘Pathological Transactions,’ vol. xv), where the lungs, liver, heart, spleen, and some other organs, were all occupied by hydatid formations. As an instance of extensive visceral infection by Echinococci in the human subject, I believe this case to be unique. The brain hydatids are particularly fine. In the specimen presented by Mr Boot, of Lincoln, the hydatid, two inches in diameter, is lodged in the anterior horn of the left ventricle. One of the peritoneal cases is remarkable for the amount of forward displacement of the pelvic viscera, caused by four or more hydatids, each of them nearly as large as a cricket-ball. Amongst the abdominal cases I have included a recent preparation, to which Mr Stewart has called my attention. The hydatid in question, of the size of a large lemon, existed near the fundus of the bladder, its walls being one third of an inch in thickness, and forming an unusually firm tumour. Of all the fine specimens of hydatids in the collection, however, none have struck me so much as those affecting the bones. There is a humerus, taken from a man thirty-four years of age, in which the shaft is occupied throughout by small hydatids that have destroyed almost all the cancellous structure; in some places, also, the absorption of the cortical layer has gone on to such an extent as to have left little more than the periosteum. Of course, the bone was at last fractured easily. It is a beautiful specimen; and the existence of Echinococcus-heads was proved by microscopic evidence. Scarcely less interesting are two preparations illustrative of Mr Traver’s case of a man, thirty-eight years of age, in whom numerous small hydatids occupied both the head of the tibia and the lower end of the femur. Each set of parasites freely communicated with the knee-joint, necessitating amputation of the limb.

The very large museum connected with Guy’s Hospital is rich in hydatids. When, some time ago, I spent several days in going over the collection, I examined seventy-six preparations, representing apparently seventy separate cases of this affection. Amongst the noteworthy specimens one lung hydatid was intimately associated with a thoracic aneurism, two others being connected with the pleura; and of seven abdominal cases, five were connected with the peritoneum, one with the mesocolon, and one with the aorta. This last-mentioned instance occurred in a woman of sixty years, who, until her death, was treated for dropsy. She complained of incessant pain, which was only relieved when she rested on her hands and knees. Of the three cases affecting the heart one has been published (Mr Henderson’s), where the patient, a girl of nineteen years, died suddenly whilst in the apparent enjoyment of perfect health. In one of the other two cases (Mr May’s, of Tottenham), the left lung was also involved. One case of hydatid disease affecting the spinal column appears to have been originally an ordinary liver case. In Mr Cock’s example of genuine mammary hydatids, the hooklets and echinococcus heads were detected; but I am not sure that a similar result of microscopic examination was obtained in the equally interesting example of hydatids of the thyroid gland (also removed by Mr Cock). There are five bladder cases, all apparently genuine (of which one has been published); and there are also five other cases referred in the catalogue to the kidneys, of which I regard two as doubtfully parasitic in character. Of three cases of hydatid growths occupying the soft parts of the thigh, two were under Mr Bryant’s care. The museum likewise contains an old preparation of hydatids of the tibia, but its history has been lost. There are also two brain cases, besides upwards of a score of more or less characteristic and instructive cases of hydatids affecting the liver.

Scattered amongst the museums connected with the larger provincial schools and recognised hospitals there must be a great many valuable preparations of hydatid disease; at all events, I judge so from the inspection I have incidentally made of a few of the collections.

Of eleven preparations of human hydatids which I observed in the Cambridge Anatomical Museum, apparently representing the same number of cases, seven were connected with the liver and one with the lungs. Those hydatids displayed in the “special series” of entozoa were of uncertain seat. From the recently published and valuable ‘Notes’ by Dr Bradbury, I have no doubt that considerable additions have been made to the Cambridge Collection since my last visit.

The museum at Oxford contains some choice specimens of hydatids, but I have only personally inspected a few of them. In the absence of original notes, however, I am indebted to the kindness of Mr W. Hatchett Jackson for supplying me with several interesting particulars. The anatomical department of the Oxford Collection shows from one particular case two hydatids that were found “under the dura mater.” In the pathological department we find one hydatid from the liver of a male subject, and also a preparation showing a number of small hydatids that were “coughed up from the lungs of a female.” There are also in this department (Dr. Acland’s) two examples of hydatids from the diaphragm, apparently belonging to two separate cases. One is described as a large “hydatid in the diaphragm covered by the pleura,” whilst the other is spoken of as “springing from the diaphragm and projecting into the sac of the pericardium.” There is likewise a preparation showing a number of small specimens of hydatids that were passed _per anum_ by a female. It is conjectured that they came from the liver.

The small pathological museum attached to the Brighton and Sussex Hospital is particularly rich in hydatids. Amongst others, it contains preparations illustrative of the remarkable case of hydatids in the region of the prostate, communicated by Mr Lowdell, in the ‘Lancet,’ in 1846.

The comparatively large museum adjoining the Norfolk and Norwich Hospital displays a choice series of hydatids, chiefly from the collection of the late Mr Crosse. That eminent surgeon prepared a special set of specimens to illustrate the process of natural cure by calcareous degeneration; and I may here, perhaps, be pardoned for mentioning that it was the study of these and other entozoa in Mr Crosse’s Collection, some thirty or more years ago, that first drew my attention to the phenomena of parasitic life. Illustrations of the helminths in question are still in my possession. In one case (which is instructive as indicating the possibility of death from the simplest form and commonest habitat of an hydatid) a lad, twelve years old, received a slight blow from a playmate. Something gave way, and death speedily followed. It was found by post-mortem examination that a solitary liver hydatid, rather larger than a cricket-ball, had been ruptured. Although the case is almost unique, it is nevertheless by no means pleasant to reflect upon the fact that under similar circumstances a slight blow might prove fatal to any one, no matter in what internal organ the bladder worm happened to be situated.

Before concluding my summary notice of the human hydatids contained in the metropolitan and certain other museums, there is an interesting literary contribution that I cannot pass unnoticed. In the November number of the ‘Indian Medical Gazette’ for 1870 an article occurs in which it is stated that the Calcutta Medical College Museum contains eighteen specimens of hydatid cysts of liver. This fact was, it seems, originally adduced to show, not the frequency, but rather the rarity, of the occurrence of hydatids in India. However, from a valuable communication by Dr James Cleghorn, which was published in the same periodical for the following March, it appears that hydatids of the liver are much more common in India than is generally supposed. This, he says, is owing to the circumstance that many of the so-called cases of tropical abscess are neither more nor less than examples of hydatid cysts that have suppurated. Besides Cleghorn’s evidence, we have the previous testimony of the Inspector General I. M. D., whose Report for 1868-69 I have already referred to in connection with _Cysticercus_ in beef. He says: “During some three months’ regular observation of the animals killed at the Commissariat slaughter-house here, at least 70 per cent. of the beef livers may be calculated as thus affected. Cobbold, writing of the _Tænia echinococcus_, says that ‘this little tapeworm infests only the dog and the wolf.’ Therefore, considering the immense number of pariah dogs fed on the refuse of animals infected with hydatids, it seems more than probable that the parasite must attain its strobila condition in their intestines, and through them be eventually disseminated over the pastures on which the cattle graze.”

I now turn to a neglected phase of the subject from which much practical instruction may be gathered. The consideration of the pathological phenomena of hydatid disease as it affects the lower animals is of high interest, and no prejudice should induce any medical man from accepting such useful data as may be gathered from this source. The facts of hydatid parasitism in animals, though often peculiar, are, for the most part, of an order similar to those presented in the human subject. If any medical practitioner thinks it beneath his dignity to study the pathology of the lower animals, the conduct of John Hunter in this respect is a standing protest against such narrowness.

The museum of the Royal College of Surgeons of England contains some of the finest specimens of hydatids from the lower animals that are to be seen anywhere, the very choicest of them having been selected by Hunter himself. That distinguished man sought information from every available source, and hydatids were for him of almost equal interest, whether found in the body of a human being or in the carcase of an ox or an ass. Now, at all events, neither pathologists nor sanitarians can well afford to neglect comparative pathology; and, for myself, I am free to say that the yearly exposition to the students of the Royal Veterinary College of the phenomena of parasitic life amongst animals has brought with it an ever-increasing knowledge of the most curious and often unlooked-for information. Some of the data thus supplied are quite remarkable. Let me also add that my studies of the entozoa of wild animals have put me in possession of particulars of high value in regard to the larger question of the origin of epidemics. Beasts, birds, reptiles and fishes, of every description, are liable to succumb to internal parasites, and there is practically no end to the variety of useful information to be obtained from this source. I have collected materials almost sufficient for a separate treatise on this department of the subject, but I fear I shall never have either the time or opportunity to give the facts due publicity. Here, for obvious reasons, I must for the most part restrict myself to the hydatids properly so called.

Referring, in the first instance, to the hydatids of animals that have the same mode of origin and exhibit the same general characteristics as those found in man, I notice that four of the metropolitan museums exhibit nine examples of liver Echinococci. The Hunterian Collection shows specimens of this kind from the pig, monkey, zebra, and lion. The museum at St Bartholomew’s Hospital contains two examples from the pig and one from a cow; whilst the animal liver-hydatids preserved in the King’s College and Guy’s Museums, respectively, are from the pig and sheep. That from the latter is partly calcified. Respecting animal hydatids affecting the lungs, the Cambridge Museum exhibits a simple acephalocyst from a monkey, and the Guy’s Hospital Museum shows a pulmonary hydatid from the kangaroo. In the museum at Oxford, Dr Acland’s (pathological) department shows a preparation of “one large echinococcus cyst from the abdomen of a baboon,” whilst Dr Rolleston’s department (anatomical) displays the echinococcus itself from the “cavity of the abdomen of the same animal.” The collection also contains a variety of other bladder worms from different animals. The Hunterian Museum, Lincoln’s Inn, exhibits four or five alleged examples of hydatids from the kidney of the sheep, besides another from the spleen. Some of these are of very doubtful character. A cystic kidney from the sheep, preserved in the London Hospital Museum, and originally supposed to have been due to hydatids, is (as hinted in the MS. catalogue) certainly not of parasitic origin. In regard to the occurrence of hydatids in the heart of animals the Hunterian series shows two good examples from cattle, whilst the collection at University College exhibits one taken from the wall of the left ventricle of a sow. This was presented by Dr Elliotson.

In the museum of the Royal Veterinary College there are a number of excellent preparations of true hydatids taken from various animals, especially from cattle, swine, and sheep; and there are also many kinds of bladder worms which, though often called “hydatid” by veterinarians, have a totally different origin from that of the true Echinococci. The so-called gid-hydatids (Cœnuri) and slender-necked hydatids (_Cysticercus tenuicollis_) are of this description. Specimens of the polycephalous brain hydatid, or Cœnurus, also exist in the museums connected with St Bartholomew’s, Guy’s, and St Thomas’s Hospital Medical Colleges, as well as in both the anatomical and pathological departments of the Oxford Museum. Specimens of large Cœnuri occurring in the soft parts of rabbits may be seen in the Guy’s Museum (presented by Mr Carpenter). Similar characteristic specimens exist in the Oxford Collection, labelled _C. cuniculi_, obtained from the “masseter and infraspinatus” muscles of a rabbit. My private collection also contains a recent addition of this remarkable hydatid, sent to me by Mr Alston from Ayrshire. It is the only one I have seen from Scotland. In the second half of this work these Cœnuri will again come under notice. Three examples of the slender-necked hydatid (from a monkey and two sheep respectively) may be seen in the Guy’s and University College Collections, and there are several in the museum of the Royal Veterinary College.

I cannot go out of my way to speak of other bladder worms, except so far as to call attention to the heart of a bear preserved in the museum at Guy’s, the walls of which are crowded with Cysticerci. That unique preparation ought to be carefully examined and described. The Hunterian Museum contains two magnificent specimens of hydatids affecting the bones of cattle. In the one case a solitary vesicle occupies the shaft of the humerus; whilst in the other several “acephalocysts” have taken up their residence within the cancellous structure of the ilium.

In the matter of human mortality from hydatids I have already supplied statistical evidence of the unenviable distinction which our Australian colonies exhibit, and in addition to the facts brought forward I may add that Dr Lewellin has mentioned to me a fatal case in which an hydatid occupied the whole length of the vertebral canal. The patient was under Dr Annand’s care. There could be no doubt as to the genuineness of the case, as the spinal cyst was tapped during life, when echinococcus hooklets were found.

Through Dr Lewellin I am also indebted to Dr H. B. Allen, pathologist at the Melbourne Hospital, for the particulars of a case of hydatids of the cerebrum, which are given as follows:

“J. Q--, aged 15, was admitted into the Melbourne Hospital on the 13th November, 1877, suffering from partial left hemiplegia. He rapidly became insensible and died next day. His mother furnished the following history.

“He had been woodcarting in the bush for a considerable time, and while thus engaged eight weeks before admission began to lose power in his left arm and leg; gradually the paralysis increased, and he was taken home, where he remained for six weeks. During this time he had every week an attack of severe headache, and once he lost all sight for over half an hour. Gradually the symptoms increased, and he was taken to the hospital, but even then was able to walk with assistance part of the way.

“At the autopsy, when the calvarium was removed, a large cyst about four inches in diameter was found on the mid-convexity of the right hemisphere of the cerebrum, slightly towards its anterior part. It formed a marked prominence on the anterior surface of the brain, and was bounded superficially by the pia mater and arachnoid, which were neither noticeably thickened nor adherent to the dura mater. On opening the cyst it was seen to extend inwards and abut on the wall of the lateral ventricle, and consisted of the ordinary gelatinous membrane, studded internally with little granular eminences, some pellucid, some opaque white. The contents were thin limpid fluid. The brain tissues around presented scarcely any induration. All other organs structurally healthy, congestion being the only morbid condition present.

“The specimen is preserved in the hospital museum, which contains two other preparations of hydatids in the brain, and also an hydatid cyst of large size growing from the interior of the frontal bone.”

In concluding this account of hydatids I may remark that, by the employment of sanitary measures, the disorder might, in course of time, be thoroughly stamped out. What these measures are I have already stated.

I need hardly say that the following bibliography by no means exhausts the records of echinococcus disease. In Dr Albert Neisser’s recent monograph nearly a thousand separate cases are quoted and classified. The monograph of Dr Hearn, which is not mentioned in Neisser’s work, also contains a valuable bibliography.

English literature. _Hydatids in general_ (BIBLIOGRAPHY No. 20 _a_). --_Ballard, E._ (review of Henoch), ‘Med.-Chir. Rev.,’ 1854.--_Bird, S. D._, ‘On Hydatids of the Lung; their diagnosis, prognosis, and treatment,’ 2nd edit., Melbourne, 1877.--_Busk_, “On the Nat. Hist. of the Echinococcus,” ‘Micr. Soc. Trans.,’ orig. series, vol. ii, 1849.--_Budd, G._, ‘Diseases of the Liver,’ Lond., 1845.--_Carmichael, R._ (lecture), ‘Dub. Med. Press,’ 1840, p. 91.--_Cobbold, T. S._, ‘Entozoa,’ chap. vii and viii, 1864.--_Idem_, “On Hydatid Disease” (lecture), ‘Lancet,’ June, 1875, p. 850.--_Idem_, “On Hydatid Diseases of Man and Animals” (museum specimens), in a series of articles contributed to ‘Brit. Med. Journ.,’ Oct., 1875, to Jan., 1876; fully reprinted in the ‘Veterinarian,’ Feb., 1876.--_Copland, J._ (Art. “Hydatids”) in his ‘Dictionary,’ 1848.--_Davies, T._, ‘Lond. Med. Gaz.,’ 1835.--_Gairdner, J._, and _Lee_, ‘Edinb. Med. and Surg. Journ.,’ 1844.--_Goodsir, H. S. D._ (same ref., Lee’s case), 1844.--_Goodsir, J._ (same ref.), 1844.--_Gross, S. D._, ‘Elements of Path. Anat.,’ chap. xv, Boston, U.S., 1839.--_Hawkins, C._, ‘Lancet,’ 1833.--_Hjaltelin_, ‘Edinb. Med. Journ.,’ 1867; see also Dobell’s ‘Report on the Progress of Practical and Scientific Medicine,’ London, 1870.--_Hodgkin, T._, in his ‘Lectures on the Serous and Mucous Membrane,’ 1838.--_Kerr, W._ (art. “Hydatids”) ‘Cyclop. of Pract. Med.,’ 1833.--_Leared, A._ (prevention), ‘Med. Times and Gaz.,’ 1863.--_MacGillivray, P. H._ (see below, miscell. cases).--_Murchison C._, in his ‘Clinical Lectures,’ Lond., 1868, p. 54; 2nd edit., 1877.--_Idem_, “Hydatid Tumours of the Liver; their danger, their diagnosis, and their treatment,” ‘Edinb. Med. Journ.,’ 1865.--_Nettleship, E._, “Notes on the Rearing of _Tænia echinococcus_ in the Dog from Hydatids, &c.,” ‘Proc. Royal Soc.,’ 1866, p. 224.--_Rose, C. B._, “On the Vesicular Entozoa, and particularly Hydatids,” ‘Lond. Med. Gaz.,’ 1833-4, p. 204.--_Stephens_, ‘Lancet,’ 1833; the ‘Veterinarian,’ 1831, p. 284.--_Thompson, T._ (remarks), ‘Lancet,’ 1851.--_Wilson, E._, “On the Structure, Classification, and Development of the _Echinococcus hominis_,” ‘Med.-Chir. Trans.,’ 1845.--_Yates, G._, “On Hydatid Disease,” ‘Assoc. Med. Journ.,’ vol. iii, 1855.

_Hydatids of the liver_ (BIBLIOGRAPHY No. 20 _b_).--_Abercrombie, T._, ‘Lond. Med. Journ.,’ vol. ii, p. 276, 1829.--_Alison, S. S._, ‘Lond. Med. Gaz.,’ 1844.--_Barclay_, ‘Brit. Med. Journ.,’ Nov., 1868, p. 494.--_Barker, T. A._ ‘Lancet,’ and ‘Path. Soc. Trans.’ 1855.--_Barlow_, ‘Lond. Med. Gaz.,’ 1857.--_Beith_, ‘Path. Soc. Trans.,’ 1852.--_Bradbury, J. B._ (six cases), ‘Brit. Med. Journ.,’ Oct., 1874, pp. 526-558.--_Idem_, ‘Brit. Med. Journ.,’ 1876, vol. ii, p. 646.--_Brinton_, ‘Lancet,’ 1854.--_Idem_, ‘Lancet,’ 1858.--_Bristowe, T. S._, ‘Path. Soc. Trans.,’ 1851.--_Idem_, ‘Path. Soc. Trans.,’ 1858.--_Broadbent, W. H._, “Hydatids of the Liver; Paracentesis followed by free Incision;” ‘British Med. Journ.,’ Nov. 30th, 1878.--_Brodie, B. C._ (supposed), ‘Lond. Med. Gaz.,’ 1828.--_Brook, C._, ‘Lancet.,’ Feb., 1868, p. 162.--_Buchanan_, ‘Surg. Med. Gaz.,’ 1861.--_Budd, W._, ‘Brit. Med. Journ.,’ 1859.--_Chambers, T. K._, ‘Lond. Med. Gaz.,’ 1846.--_Cox, T._, ‘Lancet,’ and ‘Med.-Chir. Trans.,’ 1838.--_Crosse, J. G._, ‘Lancet,’ 1837.--_Curling T. B._, ‘Med.-Chir. Trans.,’ 1840.--_Daly, O._ (supposed), ‘Brit. Med. Journ.,’ 1859.--_Davies H._, ‘Path. Soc. Trans.,’ 1848.--_Dickenson_, ‘Lond. Med. Gaz.,’ 1861; ‘Path. Soc. Trans.,’ 1862.--_Duncan, A._ (near the portal vein), ‘Edin. Med. and Surg. Journ.,’ 1808.--_Duncan, P. M._ (several cases), ‘Prov. Med. and Surg. Journ.,’ 1850-52.--_Elliotson, J._, ‘Lancet,’ 1832.--_Fearn, S. W._ (immense cyst), ‘Brit. Med. Journ.,’ Nov., 1868, p. 496.--_Fletcher, T. B. E._, ‘Prov. Med. and Surg. Journ.,’ 1846.--_Freer, W. G._, ‘Lancet,’ and ‘Prov. Med. and Surg. Journ.,’ 1845.--_Gaitskell, W._ (1000 discharged) ‘Lond. Med. Repository,’ 1815.--_Gulland_, ‘Edin. Med. Journ.,’ 1860.--_Harley, J._, ‘Lancet,’ May, 1866, p. 538, and ‘Med. Chir. Trans.,’ 1866.--_Idem_, in ‘St Thomas’s Hospital Reports,’ 1877, p. 291.--_Hastings, C._, ‘Brit. Med. Journ.,’ 1858.--_Heaton_, ‘Brit. Med. Journ.,’ Oct. 31st, 1874, p. 557.--_Heckford, N._, ‘Brit. Med. Journ.,’ Sept., 1868, p. 332.--_Hillier_, ‘Lancet,’ and ‘Path. Soc. Trans.,’ 1855.--_Hutchinson, J._, ‘Lancet,’ Oct., 1862.--_Inglis, A._, ‘Brit. Med. Journ.,’ 1859.--_Leared A._ (Hjaltelm’s case), ‘Path. Soc. Trans.,’ 1863.--_Logan_ (thousands present), ‘Path. Soc. Trans.,’ and ‘Med. Times and Gaz.,’ March, 1865, p. 243.--_Lyon, E._ (several cases), ‘Prov. Med. and Surg. Journ.,’ 1850.--_Murchison, C._ (rupture through pleura), ‘Path. Soc. Trans.,’ 1861.--_Idem_, ‘Lancet,’ July, p. 75, 1868.--_Page_, ‘Brit. Med. Journ.,’ and ‘Lancet,’ Nov., 1864.--_Pavy, F. W._ (expectorated), ‘Med. Gaz.,’ 1851.--_Idem_, ‘Med.-Chir. Trans.,’ and ‘Lancet,’ Sept., 1866, p. 234.--_Peacock_ (two cases, expectorated), ‘Lond. Med. Gaz.,’ and ‘Lancet,’ 1850.--_Pemberton, O. A._ (rupturing diaphragm), ‘Prov. Med. Journ.,’ 1848.--_Philipson_, ‘Brit. Med. Journ.,’ Oct. 31st, 1874, p. 557.--_Pollock, J._ (fatal), ‘Path. Soc. Trans.,’ 1854.--_Idem_ (opening into lung), ‘Lancet,’ Jan., 1865, p. 63.--_Rees, G. O._, ‘Guy’s Hosp. Rep.,’ 1848.--_Idem_ (lecture), ‘Lond. Med. Gaz.,’ 1849.--_Richards, C. C._, ‘Lancet,’ Jan., 1865, p. 261.--_Roberts_, ‘Lancet,’ 1833.--_Russell, J._, ‘Prov. Med. and Surg. Journ.,’ 1851.--_Sadler, M. T._ (Cæsarean section), ‘Med. Times and Gaz.,’ Aug., 1864, p. 141.--_Salter; H._, ‘Path. Soc. Trans.,’ 1860.--_Savory, W. S._ (letter), ‘Lancet,’ May, 1866, p. 410.--_Sherwin, H. C._ (fatal), ‘Edin. Med. and Surg. Journ.,’ 1823.--_Sibson, F._, ‘Lancet,’ July, 1868, p. 76.--_Sloane, J._ (puncture), ‘Brit. Med. Journ.,’ 1858.--_Thompson H._, ‘Path. Soc. Trans.,’ and ‘Lancet,’ 1858.--_Trimnell, G. C._, ‘Lond. Med. Repos.,’ 1821.--_Ward, S. H._, ‘Lancet,’ 1868, vol. ii, pp. 141, 305, and 474.--_Wearne, V._ (perforating diaphragm), ‘Brit. Med. Journ.,’ July, 1864, p. 31.--_Wilks_ (escaping by gall-ducts), ‘Path. Soc. Trans.,’ 1860.--_Young, J._, ‘Edin. Med. and Surg. Journ.,’ 1829.

_Hydatids of the liver and other organs together_ (BIBLIOGRAPHY No. 20 _c_).--_Beale, L._ (kidney), ‘Arch. of Med.,’ vol. i, p. 31, 1857; see also same case by _Bristowe_, ‘Path. Soc. Trans.,’ 1853.--_Billing_ (lungs), ‘Lond. M. and S. Journ.,’ 1831, p. 58.--_Griffith, J. W._ (abdomen), ‘Lond. Med. Gaz.,’ 1844.--_Heslop, T. P._ (kidney), ‘Month. Journ. of Med. Sci.,’ 1850.--_Richardson_ (kidney, Dr Mackinder’s case), ‘Lancet,’ 1855.

_Liver cases occurring in America_ (BIBLIOGRAPHY No. 20 _d_). --_Alexander, E._ (200 present), ‘Boston Med. and Surg. Journ.,’ 1838.--_Finnell_, ‘New York Med. Journ.,’ 1856, p. 216.--_Minot, T._ (expectorated), Bost. Soc. for Med. Improv., 1859, and ‘Brit. Med. and Surg. Journ.,’ 1860, p. 297.--_Webber, J. E._, ‘New York Med. Times,’ 1853, and ‘Bost. Med. and Surg. Journ.,’ 1853, p. 126.

_Hydatids of the lungs and pleura_ (BIBLIOGRAPHY No. 20 _e_). --Cholmeley, ‘Guy’s Hosp. Rep.,’ 1837.--_Dowling, F._, ‘Australian Med. Journ.,’ 1864.--_Duffin, A. B._, ‘Beale’s Archives,’ 1857, vol. i, p. 253.--_Hare,_ ‘Path. Soc. Trans.,’ 1857-8.--_Hill, J._, ‘Med. and Philos. Comm.,’ 1784, vol. ii, p. 303.--_Hutchinson, J._, ‘Path. Soc. Trans.,’ 1854.--_Kirkes, W. S._, ‘Med. Times and Gaz.,’ 1851.--_Leared, A._, ‘Path. Soc. Trans.,’ 1857.--_Peacock_, ‘Lancet,’ 1850.--_Ridge, J._, ‘Guy’s Hosp. Rep.,’ 1836, p. 507.--_Rigden, G._, ‘Prov. Med. and Surg. Journ.,’ 1852.--_Smith, F. G._, ‘North Amer. Med.-Chir. Rev.,’ 1858, p. 333.--_Todd, R. B._, ‘Med. Times and Gaz.,’ 1852.

_Hydatids of the Kidney_ (BIBLIOGRAPHY No. 20 _f_).--_Adams, A. L._, ‘Lancet,’ 1864, p. 375.--_Barker, T. H._, ‘Glasg. Med. Journ.,’ 1855-6, p. 439.--_Duncan_, ‘Liverpool Med. Journ.,’ 1834.--_Dunn, J._, ‘Lond. Med. Repos.,’ 1817.--_Fussell, E. F._, ‘Lancet,’ 1851.--_Lettsom_ (two cases), ‘Trans. Med. Soc. of Lond.,’ 1789, p. 33.--_Ward, W._, ‘Lancet,’ 1846.--_Wilson, J._ (lecture) ‘Lond. Med. Repos.,’ 1822.

_Hydatids of the spleen, omentum, and abdominal cavity_ (BIBLIOGRAPHY No. 20 _g_).--(Anonymous), ‘Edin. Med. and Surg. Journ.,’ 1819, p. 50.--_Bailey, F._, ‘Lond. Med. Repos.,’ 1826.--_Bright, R._ (remarks on cases) ‘Guy’s Hosp. Rep.,’ 1838.--_Bryant, T._ (simulating ovarian disease), ‘Guy’s Hosp. Rep.,’ 1868, p. 235.--_Budd, G._ (omentum), ‘Med. Times,’ 1838.--_Idem_ (rep. by Parsons), ‘Brit. Med. Journ.,’ 1859.--_Burman_, ‘Prov. Med. Journ.,’ 1847.--_Crowther, C._, ‘Edin. Med. and Surg. Journ.,’ 1826, p. 49.--_Greenhow, E. H._, ‘Lancet,’ 1862.--_Little, W. I._ (simulating ovarian disease), ‘Brit. Med. Journ.,’ 1857.--_Macleay, K._, ‘Edin. Med. and Surg. Journ.,’ 1806.--_Morley, J._ (partly pelvic), ‘Lancet,’ 1845.--_Newman, W._ (simulating ovarian disease), ‘Obstetr. Soc. Trans.,’ vol. iv, 1862.--_Obre_ (peritoneal), ‘Path. Soc. Trans.,’ 1854.--_Ogle, J._ (omentum), ‘Path. Soc. Trans.,’ 1860.--_Simpson, A. R._ (peritoneal), ‘Edin. Med. Journ.,’ 1861-62.--_Simpson, J. Y._, ‘Assoc. Med. Journ.,’ 1854, p. 137.--_Thompson, T._, ‘Lancet,’ 1843.--_Thompson, A. T._ (simulating ovarian disease), ‘Lancet,’ 1833.

_Hydatids within the pelvic cavity_ (BIBLIOGRAPHY No. 20 _h_). --_Birkett, J._ (voided), ‘Guy’s Hosp. Rep.,’ 1851, p. 300.--_Bryant, T._, ‘Lancet,’ 1865, pp. 566 and 589.--_Corrigan_ (ovarian), ‘Dub. Quart. Journ.,’ vol. i, 1846.--_Crampton_ (ovarian), ‘Dub. Quart. Journ.,’ vol. ii, 1846.--_Curling, T. B._ (bladder), ‘Med. Times and Gaz.,’ 1863.--_Farre, A._, ‘Lancet,’ 1862.--_Habershon_, ‘Path. Soc. Trans.,’ 1860.--_Hughes_, ‘Lond. Med. Gaz.,’ 1861.--_Hunter, T._, ‘Trans. of Soc. for Improv. of Med. and Chir. Knowledge,’ 1793, p. 34.--_Jennings_ (simulating pregnancy), ‘Dublin Quart. Journ.,’ 1855.--_Lowdell_, ‘Lancet,’ 1846.--_Maunder_, ‘Lancet,’ Sept., 1864, p. 351.--_Sadler, M. T._ (voided), ‘Med. Times and Gaz.’ 1865.--_Simon, J._ (voided), ‘Lancet,’ 1853.--_Wakley_, ‘Lancet,’ 1863.--_White_, ‘Med. Gaz.,’ 1842.

_Hydatids of the heart and blood-vessels_ (BIBLIOGRAPHY No. 20 _i_). --_Bigger_, ‘Dub. Path. Soc.’ Rep. in ‘Lancet,’ 1830.--_Budd, G._, ‘Path. Soc. Trans.,’ 1839.--_Coote, H._, ‘Lond. Med. Gaz.,’ 1854. --_Goodhart_, ‘Brit. Med. Journ.,’ Nov. 27, 1875.--_Price, D._, ‘Lond. Med. Repos.,’ 1822.--_Smith, R._, ‘Lancet,’ 1838.--_Trotter_, ‘Chem. and Med. Essays,’ 1736.--_Wilks_ (Henderson’s case), ‘Path. Soc. Trans.,’ 1860.

_Hydatids of the brain and cranial cavity_ (BIBLIOGRAPHY, No. 20 _k_). --(Anonymous) ‘Lancet,’ April, 1864, p. 444.--_Bailey, F._, ‘Lancet,’ 1825; ‘Lond. Med. Repos.,’ 1826.--_Barker, T. A._, ‘Path. Soc. Trans.,’ 1858.--_Bennett, J. R._, ‘Med. Times and Gaz.,’ Jan., 1862.--_Berncastle, J._, ‘Lancet,’ 1846.--_Bree, C. R._, ‘Lancet,’ 1837.--_Brittan, F._, ‘Brit. Med. Journ.,’ 1859.--_Burton_, ‘Med. Times and Gaz.,’ 1862.--_Dagleish, G._, ‘Lancet,’ 1832.--_Fletcher, T. B. E._, ‘Assoc. Med. Journ.,’ vol. iii, p. 161, 1855.--_Headington_, ‘Edin. Med. and Surg. Journ.,’ vol. xv, 1819, p. 504.--_Helsham_, ‘Med. Comment.,’ vol. xiii, 1788, p. 289.--_Macnamara, W. H._, ‘Brit. Med. Journ.,’ vol. ii, p. 616, 1876.--_Rigden, G._, ‘Prov. Med. and Surg. Journ.,’ 1852.--_Stewart, J._, ‘Lancet,’ 1848.--_Sturton_, ‘Lancet,’ 1840.--_Wilson, E._, ‘Lancet,’ 1848.

_Hydatids of the bones_ (BIBLIOGRAPHY No. 20 _l_).--_Cobbold, T. S._, “Notice of Specimens of Tibial Hydatids in Nottingham,” ‘Brit. Med. Journ.,’ 1865, and in the ‘Veterinarian,’ Feb., 1866.--_Idem_, “Notice of Specimens from the Tibia in the Mid. Hosp. Museum,” _ibid.--Cooper, A._, “Foster and Lucas’s case affecting the Tibia,” ‘Surg. Essays,’ Lond., 1818.--_Coulson, W._ (tibia), ‘Med.-Chir. Trans.,’ 1858; see also _Daubeny, H._, ‘Path. Soc. Trans.,’ 1858.--_Erichsen, J. E._, in his ‘Surgery,’ 4th edit., pp. 728, 823, and 948, Lond., 1864.--_Hunter, W._ (tibial, Mus. Spec. at Glasgow), quoted in ‘L’Expérience,’ 1838, p. 531.--_Keate, R._ (os frontis), ‘Med.-Chir. Trans.,’ 1819.--_Lambert, J._ (tibia), ‘Lancet,’ 1826.--_Thompson, H._ (Hearne’s tibial case), ‘Path. Soc. Trans.,’ 1859.--_Webster, F. W._ (tibia), ‘New Eng. Med. Journ. of Med. and Surg.,’ 1819.--_Wickham, W. J._ (tibia), ‘Lond. Med. and Phys. Journ.,’ 1827.

_Hydatids of the breast, muscles, and soft parts_ (BIBLIOGRAPHY No. 20 _m_).--_Adams, J._ (abdominal parietes), ‘Lancet,’ 1851.--(Anonymous), “Hyd. in the Eye of a Girl,” ‘Boston Med. and Surg. Journ.,’ 1849, p. 28.--_Baird, J._ (muscles), ‘Edin. Med. and Surg. Journ.,’ 1821.--_Birkett, J._ (mammary), ‘Lancet,’ March, 1867, p. 263.--_Brodie, B. C._ (near scapula), ‘Lancet,’ 1818.--_Bryant, T._ (thigh), ‘Path. Soc. Trans.,’ 1859.--_Idem_ (thigh), ‘Lancet,’ 1862.--_Idem_ (breast), ‘Path. Soc. Trans.,’ and ‘Lancet,’ Nov., 1865, p. 565.--_Cholmeley_ (from right side), ‘Lancet,’ 1826.--_Cooper, B. B._ (neck and breast, two cases), ‘Guy’s Hosp. Rep.’ 1851.--_Idem_, in Birkett’s work on the ‘Breast,’ p. 183; the ‘Institute,’ vol. i. p. 119, 1850.--_Dixon, J._ (neck), ‘Lancet,’ 1851.--_Henry, M._ (breast), ‘Lancet,’ Nov., 1861, p. 497.--_Hewndon, A._ (neck), by Tyson, in ‘Phil. Trans.,’ 1706-7, vol. xxv, p. 2344.--_Jones, S._ (subperitoneal), ‘Path. Soc. Trans.,’ 1854.--_Rankine, J._, “Supposed Hyd. in Synovial Sheaths,” ‘Edin. M. and S. Journ.,’ 1830.--_Sands_ (neck), ‘Amer. Med. Times,’ 1861, vol. ii, p. 376.--_White_ (breast and arm), ‘Lancet,’ 1839.

_Hydatids of uncertain seat, or miscellaneous cases and observations_ (BIBLIOGRAPHY No. 20 _n_).--_Barrett_, ‘Lond. Med. Gaz.,’ 1838.--_Durrant, C. M._ (Ipswich Hosp.), ‘Prov. Med. and Surg. Journ.,’ 1851.--_Fagge, H._, ‘Lancet,’ July, 1868, p. 76.--_Greenhow, J. M._ (intestinal), ‘Lancet,’ 1823.--_Howship, J._ (case, with speculative remarks), ‘Edin. M. and S. Journ.,’ 1835.--_MacGillivray, P. H._ (orbit, &c.), ‘Austral. Med. Journ.,’ Aug., 1865.--_Idem, ibid._, March, 1867.--_Idem_ (3rd series of cases), _ibid._, July, 1872.--_Idem_ (treatment with kamala), _ibid._, July, 1872.--_Markham, W. O._, “On the ‘son hydatique,’” ‘Assoc. Med. Journ.,’ 1856, p. 1072.--_Musgrave_ (letter to Sir H. Sloane), ‘Phil. Trans.,’ vol. xxiv, 1704-5.--_Phillips_, ‘Lancet,’ July, 1868, p. 77.--_Russell, J. J._, ‘Dub. Journ.,’ 1838.--_Salter, H._, ‘Path. Soc. Trans.,’ 1854.--_Ward, T. O._, ‘Lond. Med. Gaz.,’ 1837.

_Hydatids of animals (acephalocysts)_ (BIBLIOGRAPHY No. 20 _o_). --_Böllinger_ (see Bibl. No. 49).--_Cobbold_, ‘Manual,’ l. c. (Bibl. No. 2), 1874.--_Crisp, E._ (in a turkey and in hogs), ‘Path. Soc. Trans.,’ 1863.--_East, J._ (see Steel).--_Findeisen_, “Echin. in der Lunge,” ‘Repertorium für Thierheilkund.,’ 1875, s. 48.--_Gross, S. D._ (in swine), ‘Elements of Path. Anat.,’ 1845, p. 118.--_Hunter, J._, “A Cyst (hydatid) which was filled with water, formed in and filling up the Bone (humerus) of an Ox (from Hunterian MS.),” more fully described in the ‘Catalogue of the Mus. Lond. Coll. Surg.,’ “Path.,” vol. ii, prep. No. 864, p. 201, 1847.--_Idem_, “On Hydatids in Sheep” (supp. to Trans. of a Soc., l. c., _supra_), 1793.--_Hutchinson, J._, “Hydatid in the Eye of a Horse,” ‘Path. Soc. Trans.,’ and ‘Lancet,’ 1857.--_Huxley, T. H._, “On the Anatomy and Development of _Echinoc. veterinorum_ (from a Zebra),” ‘Proc. Zool. Soc.,’ 1852.--_Kirkman, J._, “Chronic Disease of the Bones of the Cranium of a Horse, associated with the existence of Hydatids within a Cyst at the inferior part of the Orbit,” the ‘Veterinarian,’ vol. xxxvi, p. 77, 1863.--_Lepper_, “Hydatids in the Kidney of a Lamb,” the ‘Veterinarian,’ 1863, p. 524.--_Martin, J._ (in the liver of a sow), ‘Vet. Assoc. Trans.,’ 1842-3, pp. 330 and 364.--_Moorcroft, W._ (in the brain of a cow), ‘Med. Facts and Observ.,’ vol. iii, 1792.--_Morgan, A._ (in the brain of a mare), the ‘Veterinarian,’ 1855, p. 396.--_Peech, S._ (in the muscles of a horse), the ‘Veterinarian,’ 1854, pp. 80 and 209.--_Siedamagrotzky_ (see Bibliog. No. 49).--_Simonds, J. B._, “Remarks on Mr. Scruby’s case of Hydatids in the Liver of a Sheep,” ‘Trans. of Vet. Assoc.,’ 1842-3, p. 331.--_Steel, J. H._ (in liver of a cow; Mr East’s case), the ‘Veterinarian,’ 1878, p. 441.--_Stoddart_ (in liver of a cow), the ‘Veterinarian,’ 1838, p. 637.--_Thudichum, J. L. W._ (in sheep), ‘Assoc. Med. Journ.,’ 1856, p. 195.--_Vincent, J. P._ (in horse, causing lameness), the ‘Veterinarian,’ 1848, p. 674.--_Walker, A._ (in the liver of a sow), ‘Vet. Record,’ 1846, p. 185.--_Woodger_ (in the brain of a horse), the ‘Veterinarian,’ 1863, p. 75.

_Foreign Literature. Human Hydatids_ (BIBLIOGRAPHY No. 20 _p_). --_Böcker_, ‘Zur statistik der Echinoc.,’ Berlin, 1868.--_Davaine, C._, ‘Traité’ (l. c., Bibl. No. 1), p. 350, 1860; 2nd edit. p. 369, 1877.--_Idem_, “Recherches sur les hydatides, les échinoc., &c.,” ‘Gaz. Méd. de Paris,’ 1855.--_Idem_, “Recherch. sur le frémissement hydatique,” ‘Gaz. Med.,’ 1862.--_Eschricht_, ‘Danske videnskab. selsk. forhandl.,’ 1853.--_Finsen_, ‘Ugeskrift for Läger,’ Bd. iii, 1867; see also ‘Brit. and For. Med.-Chir. Rev.,’ 1868, p. 324; also ‘Schmidt’s Jahrb. für Med.,’ 1867, s. 181.--_Guérault_, “Sur la maladie hydatique, &c.,” ‘Gaz. des Hôp.,’ 1857.--_Hearn, A. W._, ‘Kystes hydatiques du poumon et de la plèvre,’ Paris, 1875.--_Heller, A._, “Die Schmarotzer der Leber,” von Ziemssen’s ‘Handbuch d. Spec. Pathol. und Therapie,’ Bd. viii, s. 559.--_Krabbe, H._, “Maladie causée en Island par les Échinocoques,” in his ‘Recherches Helminthologiques,’ p. 41, Paris, 1866; ‘Helm. Undersøgelser,’ Copenhagen, 1865, p. 40.--_Idem_, “Die echinoc. der Islander,” ‘Archiv für Naturg.,’ 1865, and in ‘Den med. Skole i Reykjavik,’ 1868.--_Idem_ (see T. R. Jones, Bibl. No. 2).--_Leuckart, R._ (l. c., Bibl. No. 1), Bd. i, s. 335, 1863; Bd. ii, s. 859, 1876.--_Linder_, ‘Echinococcen der Leber,’ Leipsic, 1869.--_Naunyn_, ‘Archiv für Anat., Physiol.,’ &c., 1862-3.--_Neisser, A._, ‘Die echinococcen Krankheit.,’ Berlin, 1877.--_Rassmussen_, ‘Bidrag til Kundskab om Echinoc.,’ &c., 1865; see also ‘Brit. and For. Med.-Chir. Rev.,’ 1866, p. 285, and 1867, p. 424.--_Schmalfuss_, ‘Ueber Leberechinococcus,’ Breslau, 1868.--_Tommasi, T._, ‘Storia di un caso di Echinoc.,’ &c., in an appendix (Nota) to his edition of my ‘Lectures’ (Vermi, &c.), Milan, 1873, p. 153.

NOTE.--As Leuckart, Davaine, and especially Neisser offer exhaustive analyses of the French and German literature of human hydatids, I will only give the authors’ names attached to such additional foreign memoirs and cases as have been published in England. These are quoted in my ‘Introductory Treatise on the Entozoa.’ Full references will be found in the “Bibliography” of that work under the following heads:--_Andral_ (pulmonary veins), _Angeli_, _Auglagnier_ (bladder), _Baillarger_ (brain), _Boinet_ (liver), _Chaubasse_ (abdominal), _Cruveilhier_ (liver and spleen), _Dupuy_ (hydatids in animals), _Demarquay_ (liver), _Dupuytren_ (muscles and viscera, &c.), _Fouquier_ (lungs), _Gayet_ (liver), _Goyrand_ (liver), _Guérard_, _Guillot_, _Hedinger_ (brain), _Heintz_ (liver), _Held_ (thigh), _Heller_ (lip), _Klencke_ (blood, &c.), _Kuhn_, _Lafforgue_ (liver), _Legroux_, _Livois_, _Luschka_ (liver), _Martinet_ (brain, liver), _Maug_ (hand), _Meissner_, _Micheá_ (brain), _Moissenet_ (liver), _Montault_ (brain), _Morrisseau_, _Nicolai_ (liver), _Oerstelen_ (kidney), _Pohl_ (abdominal), _Quinquirez_ (bladder), _Récamier_ (abdominal), Richard (liver), Roget (lungs), Roux (pelvic), _Rüttel_ (brain), _Schleissner_, _Sichel_, _Sömmering_ (eye), _Skoda_, _Tomowitz_ (bladder), _Zeder_ (brain).

Additional references to the echinococcus disease as it occurs in animals will be found at the close of the section devoted to the parasites of Ruminants (Bibliography No. 49), and I shall recur to the subject of mortality from “worms” further on.

SECTION III.--NEMATODA (Round Worms).

_Trichina spiralis_, Owen.--The progressive triumphs of biological science are well epitomised in the history of the discovery, and in the record of the gradual manner in which we have obtained our present complete knowledge of the structure and development of this small entozoon.

Although the facts connected with the original discovery are clear and indisputable, much error still pervades foreign literature on this head. Without a doubt Mr Hilton was the first to suggest the parasitic nature of the capsules first spoken of as “gritty particles.” With Sir James Paget, however, rests the true discovery and determination of the nematoid character of the worm itself. With Professor Owen remains the honor of having first scientifically verified, described, and named the entozoon. Some have sought, without good reason, to alter Owen’s nomenclature; yet not only the generic title, but nearly all else that he wrote concerning the parasite, must be allowed to stand.

In relation to the capsules, it is true that prior claims of discovery have been put forward; but whilst Peacock’s preparation of the “little bodies” testifies to the fact of his having seen the capsules before other English observers, including Wormald, it was Hilton who first surmised their parasitic character. As for the claims of Klencke and Tiedemann, they are practically of no value, even if it be admitted that the former may have at an early period seen something resembling this nematode, and that the “stony concretions” encountered by the latter were degenerated capsules.

On no subject have I desired to write with more accuracy and precision than on this, and lest the above remarks should appear to be somewhat partial, I now purposely re-state the facts as they have presented themselves to me during a full and prolonged study of the entire literature of the subject. If it be asked with whom rests the discovery of _Trichina_, the reply must be framed with a due regard to precise issue at stake. The first recognition of the capsules as parasitic products is fairly claimed by Hilton; the worm by Paget; the zoological allocation and nomenclature by Owen; the adult worm by Virchow; the developmental phenomena by Leuckart; the rearing of the larvæ by Herbst; and to crown all, the clinical importance of the parasite by Zenker. Due regard being had to these relative claims, I think the following more extended statement will be found to be true and just in all its bearings.

In the year 1834 Sir James Paget, then a student, first actually determined the existence of the nematode entozoon, which was subsequently more completely described by Professor Owen. The discoverer was assisted by the celebrated botanist, Robert Brown, who lent his microscope for the purposes of examination. In the following year Professor Owen first scientifically described and named the flesh-worm (_Trichina spiralis_) in the published transactions of a learned society. He first fully interpreted the true zoological position of the parasite. Sir J. Paget’s colleague, Mr. Wormald, had “more than once” previously noticed the characteristic specks “in subjects dissected at St Bartholomew’s Hospital.” He transmitted the individual specimens which enabled Owen to draw up his valuable paper. It is clear, however, that Mr Hilton was the first to suggest the parasitic and animal nature of the specks observed in human muscle. As the “find” was made in 1832, he anticipated Wormald in his observation of the “gritty” particles in dissecting-room subjects, describing the bodies as “probably depending upon the formation of very small Cysticerci.” Nevertheless, according to Dr Hodgkin, “the first observation of these little bodies was made in 1828” by Mr H. Peacock. The latter made a dry preparation of the _sterno-hyoideus_ muscle to display the specks. That preparation is the oldest in existence, and may be seen in Guy’s Museum. It may further be remarked that Henle, Küchenmeister, Davaine, myself, and others, have pointed to a notice by Tiedemann as probably, or possibly, indicating a prior observation of the specks. Leuckart rejects the evidence. Dr Pagenstecher appears to be in doubt as to the nature of the bodies in question. As the passage in question possibly gave a rough and imperfect description of the now familiarly known calcified Trichina capsules, I give a translation of it (Froriep’s ‘Notizen,’ 1822, Bd. i, s. 64):--“At a post-mortem examination of a man who had been a great brandy-drinker, and who died from thoracic dropsy after several severe attacks of gout, Tiedemann found white stony concretions in most of the muscles, especially at the extremities. They lay in the cellular tissue between the fibre-bundles, frequently also attached to (or near) the walls of the arteries, being from two to four lines long, and roundish. The chemical examination conducted by Gmelin yielded seventy-three parts phosphate of lime, seven parts carbonate of lime and twenty parts animal matter, resembling albumen or fibrin.” In regard to this notice Dr Pagenstecher (‘Die Trichinen,’ s. 4) has remarked that Tiedemann’s “communication was also referred by Henle to such a parasitic development when he subsequently found Trichina; and in this sense it was afterwards received by Diesing, Küchenmeister, and Davaine. But it has been rejected by Leuckart on account of the size (from two to four lines) and seat of the concretions. True, it has never yet been observed that the capsuled Trichina (not measuring a tenth part of that diameter) subsequently constituted centres of gouty deposit exceeding their own bulk, nor is it likely that they should. Seeing, however, as we often do, that errors respecting size have crept into works on Trichina, we shall not need to lay much stress upon these statements; still less so since the notice is very superficial, and its character is essentially of a physiologico-chemical nature. But this, at least, seems to us decisive, that when Bischoff, at Heidelberg, wrote on a case which occurred in Heidelberg, not one single word was mentioned respecting a former case, if such should have happened, although Tiedemann and himself were on terms of close intimacy.” So much for Tiedemann. In regard to Klencke’s claims, the same observer writes:--“Klencke has asserted that he had already drawn Trichinæ in the year 1829, and that he had seen them again in 1831. This subsequent statement has no kind of confirmation. The unreliableness, mistakes, and self-deceptions in the helminthological writings of Klencke have been repeatedly exposed some twenty years ago.” Prior to this criticism by Pagenstecher, Professor von Siebold and several other well-known helminthologists had already commented on Klencke’s assertions in the same destructive manner.

In regard to the experimentation and the valuable instruction thus acquired, it appears that Herbst was the first to rear muscle-flesh-worms, or encapsuled Trichinæ, in animals (1850); whilst Virchow was probably the first to rear and recognise sexually-mature intestinal Trichinæ in a dog (‘Deutsche Klinik,’ 1859, s. 430); yet, without doing injustice to others, it must be added that it remained for Prof. Leuckart to offer a full, complete, and correct solution of the principal questions relating to the source and mode of genesis of the flesh-worm (1860). Leuckart likewise did good service by disproving the erroneous views that had been put forth by Küchenmeister. Lastly, all these brilliant results culminated in the clinical observations of Zenker, who opened out a new epoch in the history of trichinal discovery. Professor Zenker was the first to detect the young in the act of migration, and he likewise primarily demonstrated the fact that the larval parasites were capable of producing a violent disease in the human body.

Never in the history of biological science have more valuable issues followed the method of experiment upon animals. Not only has human life been thus saved, but animal life also. State-medicine and sanitation have received an immense impulse. The good that has already resulted is simply incalculable; nevertheless, in the eyes of a set of ignorant fanatics who infest this country, all experiments “involving cruelty to animals” ought to be prevented at any cost. The further progress of biological science in England has hereby sustained a severe check.

The _Trichina spiralis_ in its sexually-mature state is an extremely minute nematode helminth, the adult male measuring only the 1/18th of an inch, whilst the perfectly developed female reaches a length of about 1/8″. The body is rounded and filiform, usually slightly bent upon itself, and rather thicker behind than in front, especially in the males. The head is narrow, finely pointed, unarmed, with a simple, central, minute oral aperture. The posterior extremity of the male is furnished with a bilobed caudal appendage, its cloacal or anal aperture being situated between these divergent appendages. The penis consists of a single spicule, cleft above, so as to assume a V-shaped outline. The female is stouter than the male, bluntly rounded posteriorly, having the genital outlet placed far forward, at about the end of the first fifth of the long diameter of the body. The eggs measure 1/1270″ from pole to pole. The mode of reproduction is viviparous.

As commonly observed in the human body our young Trichinæ appear as spirally-coiled worms in the interior of small, globular, oval, or lemon-shaped cysts, which latter appear as minute specks scarcely visible to the naked eye. These specks resemble little particles of lime, being more or less calcareous according to the degree of degeneration which their walls have undergone. In shape and general aspect they are not altogether unlike the eggs of certain nematoid worms, but their size alone sufficiently distinguishes them. They measure on an average 1/78″ in length by 1/130″ in breadth. The organised capsules are not essential to the further development of the parasite, and are rather to be regarded as abnormal formations, or rather, perhaps, as products resulting from an effort of nature to protect and thus prolong the life of the occupant. They are frequently altogether wanting. The capsuled Trichinæ measure 1/23″ in length by about 1/630″ in breadth. When fully formed they not only exhibit a well-marked digestive apparatus, but also reproductive organs, which are often, indeed, sufficiently developed to determine the sex.

Notwithstanding the large number of experiments that have been more or less recently made by investigators, little or nothing has been discovered calculated to disturb the conclusions set forth by Leuckart, who writes as follows:--“(1) _Trichina spiralis_ is the juvenile state of a little round worm, previously unknown, to which the generic title of Trichina must remain attached. (2) The sexually mature Trichina inhabits the intestinal canal of numerous warm-blooded animals, especially mammalia (also of man), and constantly in great numbers. The duration of its life extends from four to five weeks. (3) At the second day after their introduction the intestinal Trichinæ attain their full sexual maturity. (4) The eggs of the female Trichinæ are developed within the uterus of the mother, into minute filaria-like embryos, which, from the sixth day, are born without their egg-shells. The number of young in each mother-worm is at least from ten to fifteen thousand. (5) The new-born young soon after commence their wandering. They penetrate the walls of the intestine and pass directly through the abdominal cavity into the muscles of their bearers, where, if the conditions are otherwise favorable, they are developed into the form hitherto known. (6) The directions in which they proceed are in the course of the intermuscular connective tissues. (7) Only the striped muscle (that of the heart excepted) contains Trichinæ. The majority of the wandering embryos remain in those sheathed muscular groups which are nearest to the cavity of the body, especially in those which are smaller and most supplied with connective tissue. Speaking generally, their number decreases with the distance from the abdomen, being, however, more numerous in the anterior half of the body. (8) The embryos penetrate into the interior of the separate muscular bundles, and here already, after fourteen days, acquire the size and organisation of the well-known _Trichina spiralis_. (9) Soon after the intrusion of the parasite the infested muscular fibre loses its original structure, the fibrillæ collapse into a finely granular substance, whilst the muscular corpuscles change into oval nucleated cells. (10) The infected muscular bundle retains its original sheathing up to the time of the complete development of the young Trichinæ, but afterwards its sarcolemma thickens, and begins to shrivel at the extremities. (11) The spot inhabited by the rolled-up parasites is converted into a spindle-shaped widening, and within this space, under the thickened sarcolemma, the formation of the well-known lemon-shaped or globular cysts commences by a peripheric hardening and calcification. This degeneration commences several months after the wandering. Immature muscle-Trichinæ are not capable of producing infection. (12) The migration and development of the embryos also take place after the transportation of impregnated Trichinæ into the intestines of a new host. (13) The further development of the muscle-Trichinæ into adult animals is altogether independent of the formation of the calcareous shell, and occurs as soon as the former have reached their completion. (14) Males and females are already recognisable in their larval state. (15) The immigration of the Trichina-brood in masses produces very grave or even fatal consequences, such as peritonitis (from the embryos perforating the intestinal walls), pain, and paralysis (resulting from the destruction of the infected muscular fibres). (16) The infection of man occurs especially through swine. (17) The muscle-Trichinæ are so capable of resistance that they are by no means in all cases destroyed by the ordinary methods of roasting, cooking, pickling and smoking. (18) As a rule, swine obtain Trichinæ from rats, to which latter we also as the natural bearers have to convey them. Microscopic examination of flesh is, therefore, urgently recommended as a public preventive against all danger from Trichinæ.”

As a summary the above conclusions are well nigh exhaustive; but whilst I purposely avoid entering into mere clinical details, there are points of hygienic interest to which I must allude. Thus, as regards the number of larval Trichinæ in any one “bearer” at a time, this, of course, must be extremely variable, but it may amount to many millions. In one of the cats on which Leuckart experimented, he estimated a single ounce of its muscle-flesh to harbour no less than 325,000 Trichinæ. I find that a relatively similar degree of infection in an ordinary human “bearer” would yield thirty millions. In the case of one of my own experimental animals, a pig, I reckoned that there were at least sixteen millions of Trichinæ. The larvæ were about ten months old and enclosed within perfectly formed capsules; nevertheless, the animal had never displayed any symptom of irritation. In a trichinised human subject, examined by Dr Thudichum, it was estimated that 40,000,000 parasites were present. My own estimate, calculated from specimens of muscle obtained from the same case, gave 100,000,000 as the approximate number of worms present. In the only outbreak of Trichinosis occurring in England, details of which will be given further on, I found that the flesh of the hog that had caused the local endemic contained upwards of 80,000 Trichinæ to the ounce. The consumption of a pound of such flesh would be capable of producing a collective progeny of something like 400,000,000 within the human “bearer.”

In the year 1865 I conducted a series of experiments upon upwards of a score of animals, including seven birds, the latter all yielding only negative results. So far as muscle-Trichinæ were concerned my experiences accorded with those of Professors H. A. Pagenstecher and C. J. Fuchs, at the Zoological Institute in Heidelberg. These experimenters found that the ingested muscle-Trichinæ acquired sexual maturity within the intestinal canal of their avian “hosts;” but they never found young Trichinæ in the muscles of the birds, nor did they perceive any evidences of an attempt on the part of the escaped embryos to effect a wandering or active migration on their own account. Clearly, if the bird’s intestinal canal were a proper territory for the residence of sexually mature Trichinæ, we should have found abundance of wandering non-encapsuled flesh-worms and also sexually-immature muscle-Trichinæ enclosed in well-formed capsules. Not a few persons still entertain the notion that Trichinæ are liable to infest all kinds of warm-blooded, and even also many kinds of cold-blooded animals, such as reptiles and fishes. Certain nematodes found in earth-worms have been described as Trichinæ; and consequently, pigs and hedgehogs were said to become trichinous through eating these annelids. The minute flesh-worms described by Bowman from the muscle of the eel are not true Trichinæ, any more than the somewhat similar parasites which Eberth found to infest the muscles of the frog. The same may also be said of Dr Salisbury’s urinary Trichinæ, which are the larvæ of _Filaria Bancrofti_.

Deducting the seven birds, and also six other animals where no examination after death was possible, I ascertained the result of my worm-feedings in sixteen instances. Nine of the experiments were entirely successful, the infected animals comprising four dogs, two cats, one pig, one guinea-pig, and a hedgehog.

Carnivorous mammals, especially those subsisting on a mixed diet, are the most liable to entertain Trichinæ, but it is quite possible to rear them in herbivora. Thus, Pagenstecher and Fuchs succeeded in rearing muscle-Trichinæ in a calf, and they found three female intestinal Trichinæ in a goat, but apparently no muscle-flesh-worms, although twenty-seven days had elapsed since the first feeding with trichinised rabbit’s flesh. In three sheep on which I experimented no trace of Trichinæ could be found. There is no practical need for any further experiments on herbivora, for it is quite clear that, in their natural state, herbivorous mammals can seldom have an opportunity of infesting themselves, whilst the reverse is the case with swine, carnivorous mammals, and ourselves. Because many quadrupeds become trichinous, it does not follow that all mammals are liable to be infested. In the case of most parasites we find the species limited to a larger or smaller number of hosts. On the other hand, in not a few cases, the range of the entozoon is limited to a single territory or host.

In conducting the experiments above mentioned I was assisted by Professors Simonds and Pritchard, of the Royal Veterinary College. As they were the only researches conducted on any considerable scale in England, I subjoin a few details of them. Dr Thudichum’s experiments were, I believe, confined to rabbits.

_Exps._ 1 and 2.--On the 15th of March, 1865, an ounce of flesh containing Trichinæ was administered by myself to a black bitch. The dog being destroyed five days subsequently, neither intestinal nor muscle-Trichinæ were discovered. It was thought that the dog had thrown up the bolus, which was strongly saturated with chloride-of-zinc solution. The bolus consisted of a portion of the _pectoralis major_ of a subject brought to the dissecting-room at the Middlesex Hospital. The cysts were highly calcified, but the majority contained living embryos, which were quite unaffected by the zinc solution injected into the body to prevent decomposition. At the same date a small white puppy was experimented on and examined with precisely the same results. In either case it was too early to expect muscle-flesh-worms to have become developed.

_Exp._ 3.--Half an ounce of the same trichinous human flesh was given (at the same date) to a black-and-tan puppy reared at the Royal Veterinary College, a second “feeding” being administered on the 21st of March, or six days after the first. In this case Mr Pritchard, who fed the animal, took the precaution to chop the muscle into small pieces, and to mix it with other food, in order that the flesh might be the more readily retained in the stomach. The puppy was not destroyed until the 15th of the following June, when, on examination, numerous encysted but non-calcified muscle-Trichinæ were found in all the voluntary muscles subjected to microscopic scrutiny.

_Exp._ 4.--An ounce of the same flesh was given to a dark-colored pig on the 15th of March, and again on the 20th, several other “feedings” being also administered during the month of April, 1865. It was destroyed on the 16th of May, but no Trichinæ were detected.

_Exp._ 5.--An ounce of the same human muscle-flesh administered to a small sheep (which was subsequently killed on the 29th of June) also produced negative results.

_Exps._ 6 and 7.--“Feedings” were at the same time administered to a rat and mouse. The mouse died on the 2nd April, when I examined its muscles without success. On the following day the rat unfortunately made its escape, but whether trichinised or not cannot be said.

_Exp._ 8.--An ounce of trichinous human flesh was given to a donkey, in the form of “balls,” on the 20th of March; and during the month of June four other separate “feedings” with trichinous dog’s flesh were also administered. The animal was removed from the College without the result being ascertained.

_Exp._ 9.--From the 15th to the 20th March, 1865, inclusive, three small Trichinæ “feedings” were likewise administered to a guinea-pig. This little animal was not destroyed until the 15th of the following June, when a positive result was obtained. The _pectoralis transversus_ and other muscles were found to harbour a considerable number of encysted Trichinæ.

_Exp._ 10.--On the 20th March, and again on the 21st (1865), “feedings” from the same human subject were administered to a hedgehog. On the 26th of April the animal seemed to be attacked with symptoms of Trichinosis. It refused food, kept its head extended, and the eyelids closed. On the 27th it appeared much worse, and on the morning of the 28th it was found dead. On the 29th I examined the flesh, and found abundance of living Trichinæ in the muscles. The capsules were very thin and transparent. A few days later Mr Simonds also examined the flesh, and confirmed this result.

_Exps._ 11 and 12.--Two chickens were fed, on the 21st of March, with the same material. One of the birds died on the 24th, when I examined the intestines and detected one or two very minute nematodes, which, at the time, I believed to be imperfectly developed Trichinæ, but subsequently saw reason to alter my opinion. The other bird died on the 3rd of April, and certainly contained no muscle-Trichinæ.

_Exp._ 13.--On the 22nd and 23rd of March “feedings,” amounting to an ounce of flesh in all, were given to a mole. This animal was returned to the care of Mr Charles Land, who had previously sent it to the Veterinary College. He subsequently reported that, after observing the mole to be “working” for two or three days, he lost all trace of it, and concluded that it had either escaped or was dead.

_Exp._ 14.--On the 1st and 2nd of May portions of the left fore extremity of the hedgehog (in which we had successfully reared Trichina from the Middlesex-Hospital subject) were offered by Mr Simonds to a cat. It ate the flesh very readily, consuming the entire limb. On the 15th of the following June the cat was killed, when living Trichinæ were found within all the muscles which we examined.

_Exp._ 15.--At the same dates a young terrier dog was similarly treated, but did not take the “feeding” so readily. In this case the left hind extremity of the hedgehog was employed, and what was not eaten voluntarily was forcibly introduced. On the 1st of June the dog was attacked with “distemper,” and died on the 8th of the same month. On examination we found several living Trichinæ in the _sterno-maxillaris_ and other muscles. Some of the parasites were encysted.

_Exp._ 16.--From the 9th to the 12th of June inclusive four separate worm-feedings with the flesh of the trichinised terrier-dog were administered to a crow. The bird was killed some months afterwards and sent to me for examination. Its muscles were entirely free from Trichinæ.

_Exp._ 17.--From the 9th to the 17th of June inclusive seven separate worm-feedings were administered to a pig. One of the “feedings” was with the trichinised guinea-pig’s flesh, the others from the dog. This animal was not destroyed until the 4th of April, 1866, when all the muscles which I examined were found extensively infested with Trichinæ. There were probably not less than 16,000,000 present, all being alive and enclosed within perfectly-formed capsules, none of which latter exhibited any traces of calcareous deposition.

_Exp._ 18.--Four separate feedings with trichinous dog’s flesh were likewise, at the same dates as the foregoing, administered to a rat. This experimental animal, however, like the one previously mentioned, contrived to make its escape. I fear it was well trichinised.

_Exp._ 19.--About the same date trichinous “feedings” were given to a black puppy (bred at the Veterinary College). The dog was killed on the 18th of August, 1866, having also been made the subject of an echinococcus-feeding, when I found abundance of encysted Trichinæ within the voluntary muscles.

_Exp._ 20.--Four separate worm-feedings with the flesh of the trichinised guinea-pig were given to a sheep on the 15th, 16th, 17th, and 19th days of June, 1865. The experimental animal was destroyed on the 29th of the same month, but the result was negative.

_Exps._ 21 and 22.--“Feedings” with the guinea-pig’s flesh--four in the one case and three in the other--were also administered by Mr Simonds (from the 15th to the 19th of June, inclusive) to a chicken and goose respectively. These birds were destroyed some months afterwards and sent to me for examination, but the most careful scrutiny failed to detect any Trichinæ within their muscles. The goose was cooked and eaten without the slightest hesitation. The chicken I found too tough for consumption.

_Exp._ 23.--On the 28th of March, 1866, I obtained a small quantity of muscle from a highly trichinised German subject, who died from the effects of an accident at the London Hospital the day previous. The case was fully reported by Dr Thudichum in a new journal, called ‘Scientific Opinion’ (No. 4, April 25th 1866, p. 55). During the same day (at 2.30 p.m.) I fed a dog with part of this human flesh. On the morning of the 31st I killed the dog, and examined the intestinal canal (at 11.30 a.m.), which revealed the presence of sexually-mature living Trichinæ. The males (of one of which I retain an accurate figure) displayed the characteristic bilobed caudal appendage, leaving no doubt as to their source and nature. I have mentioned the precise time of the experiment, in order to show that a period of sixty-nine hours proved amply sufficient for the development of the young muscle-flesh-worms of the human subject into the sexually-mature adult Trichinæ of the dog.

_Exp._ 24.--With another portion of this human flesh (taken from the muscles of the tongue) in which the Trichinæ were extraordinarily abundant, I fed a cat. In about ten days the animal showed the most marked symptoms of trichinosis. It refused to eat; the eye lost its lustre; the body became very thin, and I thought the animal would die. By very great care, keeping it warm before the fire, and subsequently inducing it to take a little milk, the creature improved, gained flesh, and eventually recovered. About three months afterwards I destroyed this cat, when on examining the _panniculus carnosus_, _latissimus dorsi_, and other superficial muscles, I found great quantities of well-developed, capsuled Trichinæ. Although the animal had swallowed scarcely a quarter of an ounce by weight of the infested flesh, yet thousands of parasites had been propagated and dispersed throughout its muscular system. In this way the helminthiasis nearly proved fatal to my cat. As has been already stated, Dr Thudichum, who I believe had an opportunity of examining the corpse of this trichinised German, estimated the number of parasites in his body at 40,000,000. I do not think this estimate likely to be exaggerated, for if all the flesh had been infested to the extent I found to obtain in respect of the muscles of the tongue, I believe 100,000,000 would have been nearer the mark. In places the point of a needle could scarcely be thrust between the capsules, so closely were they agglomerated.

_Exp._ 25.--From the 19th to the 25th of April, 1866, inclusive, daily administrations of trichinous pork, in the form of bolus, were made to a sheep by Mr Pritchard. The Trichinæ were obtained from one of our experimental animals at the Veterinary College, about two ounces of the flesh being given at each feeding. The flesh of this sheep (destroyed in the following November) failed to give any indication of the presence of parasites.

_Exps._ 26 and 27.--About the same time, and occasionally at intervals extending over a period of five weeks, Mr Pritchard also fed two young fowls with the same trichinous pork. Towards the close of October, 1866, both birds died, when Mr Pritchard carefully examined the flesh of them, but failed to find any trace of Trichinæ.

_Exps._ 28 and 29.--From April 2nd to the 9th of the same month, 1866, inclusive, feedings with trichinous pork were likewise given to two dogs. These animals were destroyed and examined by Mr Pritchard in November, 1866, but the result appears to have been negative.

It is perfectly certain that the infection of man by Trichina is invariably due to the ingestion of verminiferously diseased meat, and as remarked in my ‘Lectures,’ whenever the parasites are taken in large numbers unpleasant symptoms soon show themselves in the infested person. There is, first of all, restlessness, loss of appetite, and more or less prostration. This is succeeded by rheumatoid pains in the limbs, with the frequent accompaniment of considerable swelling. The pain is not situated in the joints, but in the intermediate soft parts. In severe cases the limbs are drawn up and half bent, as in instances of severe and continued cramp. Sometimes the suffering is excruciating and unbearable, patients having been known to request the surgeon to put an end to their lives. In the worst forms of the malady death rapidly ensues from diarrhœa and exhaustion. If the parasites have gained admission to the muscles all hope of destroying them is at an end; but if a person suspects himself to have eaten diseased or trichinised meat he should lose no time in seeking professional assistance, seeing that the administration of suitable anthelmintics might be the means of saving his life, whereas a few days’ delay would probably prove fatal. So long as the worms remain in the stomach or intestinal canal they can be got rid of, but when once the trichinal brood have invaded the flesh then they cannot be expelled. As remarked in my ‘Entozoa,’ it is easy to perceive that although, in the majority of instances, Trichiniasis does not cause death, yet the percentage of fatal cases is by no means insignificant.

The notion that particular breeds of swine are more liable to be infested than others is absurd, since infection must be due to the facilities offered for swallowing garbage, especially dead rats. According to Drs Belfield and Atwood 8 per cent. of slaughtered American swine contain Trichinæ. In infested hogs they found from 35 to 13,000 parasites in a cubic inch of muscle, and by repeated feedings they succeeded in rearing about 100,000 Trichinæ in the body of a rat.

In regard to the disease in man let us glance at the phenomena that presented themselves in Plauen, a town of Central Saxony. Drs Böhler and Königsdörffer, who first saw this disease and treated it, state, according to Leuckart, that “the affection began with a sense of prostration, attended with extreme painfulness of the limbs, and, after these symptoms had lasted several days, an enormous swelling of the face very suddenly supervened. The pain occasioned by this swelling and the fever troubled the patients night and day. In serious cases the patients could not voluntarily extend their limbs, nor at any time without pain. They lay mostly with their arms and legs half bent--heavily, as it were, and almost motionless, like a log. Afterwards, in the more serious cases, during the second and third week, an extremely painful and general swelling of the body took place; yet, although the fifth part of all the patients were numbered amongst the serious cases, only one died.”

Satisfactory as it may be to note the numerous recoveries which take place, this circumstance is very much marred by the fact that a large proportion of the patients suffer the most excruciating agony. In the main it will be observed that Böhler’s and Königsdörffer’s experience, as recorded by Leuckart, corresponds very closely with that given by other observers. The symptoms, moreover, are very similar to those produced in the original case published by Zenker. In this case, which occurred in the Dresden Hospital (1860), the patient was a servant girl, aged twenty, and the principal symptoms were loss of appetite, prostration, violent pains, contraction of the limbs, and finally œdema, which, in association, perhaps, with a certain amount of pneumonia, terminated her career within a period of thirty days. The post-mortem appearances showed that the larval Trichinæ were the cause of death. The intestinal canal contained numerous sexually-mature worms.

The effects produced by Trichinæ on animals are similar to those occasioned in man. The phenomena were summarised by Davaine (in the journals quoted below) in 1863 as follows:

“The first phase is characterised by intestinal disorder, produced by the development of the larvæ in large numbers, and their adhesion to the mucous membrane of the intestine. In this stage M. Davaine has seen rabbits die with intense diarrhœa; one of two cats which he fed with trichinised meat had diarrhœa for at least a fortnight, but survived. Of five or six rats fed on a similar diet, one only, which was pregnant, died of diarrhœa, after abortion, on the eighth day. According to M. Leuckart, the passage of the embryos of Trichinæ through the intestinal walls sometimes produces peritonitis. This intestinal phase often becomes blended with the next; it may be relieved by the expulsion of the worms by means of the diarrhœa, or may cease with the natural death of the worms.

“The second stage presents general symptoms--muscular pains, &c. These phenomena are dependent on the introduction of the Trichinæ into the muscles; they rapidly acquire their maximum intensity, and have not a long duration. The appearance and duration of this stage are in complete relation with the development and length of sojourn of the Trichinæ in the intestines; in fact, in this entozoon, oviposition is not slow and of long duration, as in many nematoid worms; the genital tube is rapidly formed, and the ova, in its whole length, are developed almost simultaneously, so that the embryos, arriving soon at maturity, are at once thrown out in large numbers into the intestine, and the mother Trichina dies exhausted. If it be remembered that the embryos do not escape before the eighth day, that a certain number of days are required for their arrival in the muscles, and that new ones are not produced after six or seven weeks, it will be understood that the first symptoms of this stage can scarcely appear until the end of a fortnight after ingestion of the diseased food, that they must continue four or five weeks, and that after this they may disappear. This course of events is observed in animals; and in man the symptoms of this stage have shown themselves and become aggravated from the third to the sixth week after infection. Most animals die during this stage; rabbits rarely survive; rats, on the contrary, generally resist it.

“If the animals do not die of the general symptoms or local disturbances proper to these two stages, the inflammatory symptoms cease, respiration becomes natural, and order is re-established. But, in some cases, the number of cysts formed in the muscles are sufficiently great to impede them in the proper exercise of their functions, and hence arises general debility, a kind of consumption which persists or becomes aggravated, and the animal dies of marasmus. M. Davaine has noticed this in rabbits, but especially in a rat.

“Recovery from these phases of trichinal infection may be apparently perfect. A rabbit which M. Davaine kept during five months became large and fat, although it had a large number of Trichinæ in its muscles; a rat which had had these entozoa in considerable numbers during six months was, to all appearance, in good health. Hence he concludes that the Trichinæ produce symptoms only when they are in the intestinal canal, and when they are entering the muscles. Having become lodged in their cysts among the muscular fibres, they may remain harmless for an indefinite time. In every case except one, down to 1859, Trichinæ have been found in the bodies of persons who have died of disease (generally chronic) or by accident; or in the dissecting-room, in bodies regarding which the previous history could not be obtained. In most cases the cysts contained a cretaceous or fatty deposit, showing that they had probably existed several years.

“The observations which have been made on the human subject, in regard to the symptoms caused by Trichinæ, show that they belong, as in animals, to the initial period of infection. They consist in intestinal and in muscular lesions; the latter coincide with the entrance of the parasite into the muscles, and are truly traumatic. In Zenker’s case the intestinal symptoms were swelling and pain; in a case described by Friedreich diarrhœa was present. In all cases the most remarkable symptoms were violent rheumatoid pains in the muscles, not in the joints, which were considerably aggravated by attempts to extend the half-bent limbs. The other symptoms have been variable, but have had a strong resemblance to those of typhoid fever. In several cases there has been abundant sweating; and in one there was a very remarkable miliary and furuncular eruption. The animal heat was diminished in Friedreich’s case; and in those observed in Voigtland by Freytag the temperature never exceeded 102° Fahr.

“The progress, duration, and severity of the disease in man are in relation to the number of Trichinæ taken into the digestive canal. Of sixteen patients observed at Plauen by Drs Böhler and Königsdörffer, eight, who were moderately affected, recovered in a month; four, more severely diseased, were ill two months; of four others, one died with ascites and colliquative diarrhœa at the end of two months, and three recovered slowly at the end of three or four months. Recovery does not imply the death of the Trichinæ, it follows their enclosure in cysts.

“The diagnosis of trichinal infection has several times been made in the living human subject by removing a portion of muscle. M. Davaine thinks it probable that, during the first six or eight weeks of the disease, the diagnosis may be confirmed by searching for adult Trichinæ in the alvine evacuations, produced naturally or by means of a purgative.

“The prophylactic treatment consists simply in the avoidance of uncooked meat. The medicinal treatment must vary with the stage of the disease. At first, attempts must be made to expel the parasites from the intestines by purgatives and anthelmintics. Which amongst the latter is the most energetic is not yet determined. Calomel is, perhaps, M. Davaine thinks, the best. After six or eight weeks all treatment directed towards the intestines is superfluous. It is scarcely probable that any substance will act on the larvæ disseminated through the muscles. Friedreich has recommended picronitrate of potash; but, in the case in which he used it, live Trichinæ were found in the muscular tissue after the patient was considered to be cured.”

In regard to the possibility of curing trichiniasis by the administration of drugs which should act as trichinacides upon the parasites in the condition of flesh-worms, the absurdity of the proposal only equals that which was made in reference to the destruction of hydatids by the administration of kamala. As has been shown in the record of my first experiment the flesh of a trichinised corpse may be thoroughly saturated with a strong solution of chloride of zinc, and yet the worms will remain quite unaffected.

In reference to the dangers arising from the consumption of diseased meat, Professor Gamgee has very cogently put two questions:--“Did Moses know more about pigs than we do?” “Was it a knowledge of the parasitic diseases of swine and man that led Moses to condemn pork as human food?” Mr Gamgee answered both questions negatively, thus:--“The wisdom of the Mosaic law can only be justly estimated with a knowledge of the accidents arising in warm countries from eating pork throughout long and hot periods of the year; and there is no doubt that the direct evil results, as manifested by human sickness, led to the exclusion of pork from the list of Israelitish viands. The masses of measly pork which may be seen hanging from the butchers’ stalls in Southern Europe prove that the long-legged swine which hunt the forests for acorns, and rove about to pick up all kinds of offal, are often unfit for human food, and that they were so to no less extent in the land of Israel is probable.” As supplementing Professor Gamgee’s argument, I may remark that, if Moses had been furnished with special knowledge beyond that of his contemporaries, he would not, in the matter of meat-parasitism, have confined his restrictions to pork. Had he possessed any knowledge of measly beef, he would not have spared the ox on the ground that although “it divideth the hoof, yet it cheweth the cud.” As regards home-reared animals, Professor Gamgee cogently remarked: “It is interesting to observe that parasitic maladies in the pig specially abound in that section of the United Kingdom where swine live most amongst human beings. The Yorkshire and Berkshire pigs, in their native counties enclosed in the farmyards of their breeders, are free from worms which are likely to live in the body of man. The Irish pig is the one most commonly injured by entozoa, and the reason for this is evident when we know how much the cottager relies on rearing a porker which is permitted the free range of house and road, where every description of filth is devoured, charged with the ova of parasites expelled by man or some of the lower animals.” He also adds: “The conditions under which we live in the British isles are certainly much less favorable to the propagation of worms; but we disregard, in our ignorance, the most common precautions to protect ourselves from loathsome diseases, and not only permit dogs to eat any kind of offal in and around slaughterhouses, but sanction the existence of piggeries where all kinds of garbage, charged with worms or their eggs, are daily devoured by swine. The majority of germs calculated to engender parasites are to be found in abundance in the contents of the alimentary canal of human beings and domestic quadrupeds. If pigs are permitted to eat these, as in Ireland or in many British piggeries, we must expect hams, bacon, and pork sausages to be charged with the embryonic forms of human entozoa. Whereas in Iceland the _dog_ is the victim of human negligence, and _en revanche_ the cause of human disease, in the British isles the _pig_ holds this unenviable position. We have good reason to believe, with Moses, that the pig is an unclean beast; but without discarding him from the scanty list of animals to be eaten, it is evident that we can purify the race of swine, and thus prevent human as well as porcine maladies.”

On the authority of Rupprecht, as quoted by Davaine, I append a list of the principal epidemics observed in Germany during the first six years immediately following the discovery of trichinosis:

1. Two slight epidemics in 1860 in the Island of Rügen; 10 to 20 patients (Dr Landois).

2. An epidemic at Stolberg, 1860 (Dr Fricinus). The number of trichinised persons was not stated with certainty.

3. Five epidemics during five summers, 1858 to 1862, at Magdebourg. The number of patients was 300, two only died (Dr Sendler).

4. An epidemic at Plauen in 1862, 20 patients (Böhler).

5. Gusten, 1861, 40 cases, all cured (Fränkel).

6. Epidemic in the Province of Armsted (Mansfeld), 1861, 8 patients.

7. Hettstädt, January and March, 1862, 8 to 10 patients.

8. Blankenburg, 1862, 278 cases, 2 deaths.

9. Calbe (Prussia), 1862, 38 cases (9 men, 25 women, 4 children), 8 deaths (Dr Simon and Dr Herbst).

10. Burg, in Magdebourg, 1863, 50 patients, 10 deaths (Dr Klusemann).

11. Quedlinburg, 1863, 9 patients, 1 death (Dr Behrens).

12. Plauen, 1863, 21 patients (Königsdörffer).

13. Falkenstein, 1863, 4 patients (Drs Bascher and Pinter).

14. Posen, August and September, 1863, 37 patients (Dr Samter).

15. Hamburg, 1863, 2 patients (Dr Tüngel).

16. Blankenburg, 1863, 32 patients, 2 deaths; new cases in 1864 (Dr Scholz).

17. Hettstädt (Prussian-Saxony), October, 1863, 158 patients, 27 deaths (Rupprecht).

18. Eisleben, December, 1863, and January, 1864, 18 cases, no deaths. This result was attributed to the employment of phosphoric acid (Rupprecht).

19. Hettstädt, February and March, 1864, 8 patients, no deaths. Two cats were also attacked, one of which died. Nearly 50,000 Trichina were counted in an infected leg of pork (Rupprecht).

20. Quedlinburg, 1864, 120 patients, 2 deaths; benzine was employed (Dr. Wolf).

21. Hettstädt, January, 1865, 15 patients (Rupprecht).

22. Berlin, 1864, 3 cases (Dr Cronfeld). Several butcher boys (Frischer).

23. Leipzig, 1864, 14 patients, 2 deaths; 4 were infested after having eaten raw beef hashed on a block which had previously received the flesh of a trichinised hog (Dr E. Wagner).

24. Potsdam, 1864, 5 slight cases (Dr Mollendorf).

25. Celle (Hanover), 1864, 8 patients (Dr Scheller and Dr Baring); Trichina proven in the pork by Gerlach. In 1855, 12 Trichina (?) patients were treated by Schuchart.

26. Hedersleben, 25th October, 1865, a pig was killed and sold; on the 28th the malady appeared amongst the workmen; 350 patients, 100 deaths. Of 100 children infected, none died. Trichina found in the autopsies (Dr F. Kratz).

Dr Davaine also adds the following outbreaks:

In Massachusetts, 1867, 6 patients from having eaten raw ham, 1 death (‘Medical Times,’ 20th April, 1867, p. 431).

Ravecchia (Bellinzona), 1868, 5 patients, 4 deaths (Dr Zangger in _Landbote_ of Winterthur).

Up to a comparatively recent date no case of trichinosis had been recognised in England during the life of the victim. As regards diagnosis, what was happening every day on the Continent was utterly unknown here. Whilst, however, not a single instance of Trichina-disease had been observed by British physicians in actual practice, as many as thirty or forty instances had occurred where the parasites in question had been found post mortem. I had myself examined the trichinised flesh taken from a dozen of these corpses, but in no instance had the faintest suspicion of trichinosis been entertained during life. The circumstances attending the only outbreak of trichiniasis that has been witnessed in England are very interesting. In the month of April, 1871, I received from Dr W. L. Dickinson, of Workington, Cumberland, specimens of pork which he requested me to examine; and in complying with his request I confirmed his opinion that the diseased meat was infested with Trichinæ. A few days afterwards I announced the discovery in the pages of the ‘British Medical Journal’ for April 22, p. 435. It happened, also, that at the time I was delivering a course of lectures before the Society of Arts; consequently, in my second discourse (which was devoted to the parasites of cattle) I gave full details of the facts that were obtained. Taking a small portion of the flesh which I judged to be affected to an average extent I addressed the audience as follows:

“If you calculate from one portion only, you might, if you had stumbled upon a part which was more infested with parasites than another, be led to over-estimate the degree of trichinisation. Taking proper precautions I have calculated that one scruple of this trichinous flesh would give us 4320 parasites, and two scruples would therefore yield 8640. Without speaking so precisely to numbers, I do not hesitate to aver my belief that there are at least 5000 of these parasites inside this small piece of ham. The number is probably close upon 8640. In one drachm that would give us 12,000, and in an ounce 103,000, according to the old apothecaries’ weight. If, however, we calculate according to the ordinary weight used by butchers, we should say that one ounce contains 437-1/2 grains of meat, and therefore the number of parasites in one ounce would be 85,000. Thus, in one ounce of meat from this particular pig you have 85,000 Trichinæ, calculated at the rate of 200 in the grain, for I have purposely cut off the odd numbers. You may say, if a person can survive 18, 20, 30, or 40 millions, he would not take much harm from eating a piece of flesh containing only 8640 parasites. Such a portion, however, would be quite sufficient to make any one of us extremely uncomfortable were we to eat it, for supposing its contained parasites to be alive, it might prove dangerous to life. Why? The explanation is this:--Half of those 85,000 parasites, at the very least, will, in forty-eight hours after ingestion, have become fully-developed females; and from each of these 42,000 there will proceed at least 1000 as a brood, so that the entire progeny (and it is they that do the mischief by their independent migrations through our tissues) will eventually yield about 42,000,000 entozoa. If we should be so voracious as to eat a pound of such trichinised flesh, then there would be 400,000,000 as the result of a single meal.

“Having detailed these facts and inferences, I now wish to bring to your notice some other particulars connected with the Cumberland outbreak.

“Dr Dickinson, of Workington, tells me that he was at first suspicious that his patients were suffering from fever, but was not quite able to make out what the disorder was. At length certain symptoms occurred, which suggested that it might possibly be the German flesh-worm epidemic making its appearance in this country for the first time, and, therefore, in view of verifying the facts of the case, he sent me portions of the flesh of the pig. He describes the symptoms, which in their character corresponded with those previously recorded as experienced by persons similarly attacked. Dr Dickinson remarks, towards the close of his communication, that the victims form a small family who have carefully reared their own swine. The British farmer is thus here introduced to us at his own table playing the part of ‘host’--at her own table, I should say, for, to be more precise, it is a widow, her daughter, and a man-servant who are suffering. Dr Dickinson informs me that for two or three weeks before he was called to see them they had been eating sausages and boiled pork from one of their own home-fed pigs, which pig, by the way, turns out to have been an old sow. He brought away some sections of the leaner portions of the flesh for microscopic examination. You will observe that there can be no mistake about the source of the food on this occasion. Hitherto, Trichina has not been observed in our British-fed swine in more than one or two, or possibly three instances. Therefore it would be very interesting to ascertain how it happened that this poor pig became trichinised. In my communication addressed to the ‘British Medical Journal,’ I wrote as follows:--“Dr Dickinson has at the present time under his care a family suffering from the so-called flesh-worm disease, resulting from the consumption of ham prepared from pigs reared by the family themselves. A portion of ham sent to me swarmed with recently encapsuled Trichinæ. Dr Dickinson being thus the first person who has diagnosed trichiniasis in the living subject in England, I hope he may be induced to give us further particulars.” The editor, in commenting upon this letter, added a practical point, which I wish especially to bring to your notice. He says:--‘The subject of parasitic diseases of domestic animals is one of widespread and increasing interest. It is immediately related to the irrigation of fields with sewage.’ The editor, of course, made this statement on independent grounds, and on his own responsibility. If he had said the subject bears an indirect relation to the sewage question, he would have said no more than is absolutely true, for, as I shall take occasion to explain, there is every reason to suppose that certain forms of parasitic disease may be propagated by means of sewage. In this connection some of you may be disposed to ask the question:--‘Are there any sources of comfort to be gathered from the facts?’ Or you may say, supposing that in future our British swine are not as free from Trichinæ as they have been hitherto, can we possibly avoid the contingency of playing the part of host to those creatures? Certainly, I reply, it is simply a question of properly cooking the food. If these farmers have not cooked their food at all, or scarcely at all, that will at once account for their being laid up. I should tell you that the lady and the daughter are recovering, and that they are convalescent, but the man-servant is very ill. If, during cooking, the flesh consumed by these persons had been raised to a persistent temperature of 170° Fahr., then, doubtless, the ingestion of trichinised pork would have done no harm. You observe that Dr Dickinson says in his letter that they partook of it roasted and boiled. Now, few of us are in the habit of eating underdone pork, although there are other meats that we devour very readily in an imperfectly cooked state. It must be remembered, also, that although the exterior may have been subjected to a temperature of 212 degrees, it by no means follows that the whole of the joint throughout must have been submitted to that temperature. Under rapid cooking, the centre of a large joint may remain much below even 140 degrees. If the man-servant ate only one ounce of the flesh with living Trichinæ in it, he will probably have at this present moment at least 42,000,000 of these guests in his muscles. You will ask, ‘Will he recover?’ ‘Yes; if he ate no more than that.’ If he has eaten 2 oz. thoroughly underdone, depend upon it he has 80,000,000, and if he has eaten 3 oz. he will have over 100,000,000 of Trichinæ in his muscles. Could he survive if he had eaten over 3 oz., and thus have 100,000,000 and upwards of these inhabitants? I think he could. We have evidence on this point from the case in which I estimated that there were upwards of 100,000,000 of Trichinæ present, and yet the man survived the attack.

“Incidentally I may remark that in the course of the last twenty years, although millions of parasites and their eggs have passed through my hands, I have almost entirely escaped infection. It is something to know what you are either handling or looking at, because there are many parasites besides Trichina which are dangerous. There are gregariniform entozoa residing in meat which we eat every day without any bad consequences. They are as harmless as cheese-mites. There is no need to be in the slightest degree nervous about flesh-food, provided it is properly cooked. I believe there will be no fatal issue in the case of any of the three individuals just alluded to, but the chief practical point before us arises out of the fact that we have here, for the first time in England, an epidemic of trichiniasis. By calling attention to the subject, it will, to say the least, suggest precautions by which future epidemics may be avoided.”

The above remarks form the substance of a lecture given on the 24th of April, 1871. A week later I delivered the third of the Cantor lectures for that year, when I took occasion to add the following particulars:

“It has been asked whether the so-called muscle-Trichinæ, after they have arrived at their destination within the flesh of man, are capable of producing any more unfavorable consequences? The answer is, Certainly not. In the case of man it would be necessary that his muscles should be eaten in order for the Trichinæ to become sexually-mature worms; and in those countries where cannibalism exists, the man-eater would himself become trichinised, and would certainly deserve his fate. I was very desirous to follow up the account of this outbreak by inquiries respecting the particular animal which had been the cause of the outbreak. I may therefore mention that my informant, Dr Dickinson, states that the family, including the man-servant, all fed together, and that they had for upwards of a fortnight eaten daily, and sometimes twice a day, sausages made from the flesh of the trichinised animal. And he adds: The meat cut from the ham and flitches, and what is called the spare-rib, was roasted before the fire or in the frying-pan. Occasionally it was cooked in the oven. Dr Dickinson ascertained from the mother that she liked her meat to be underdone, and thus, therefore, there is very little doubt that the meat was generally undercooked. The man, a strong labourer, had a good appetite, and would therefore get a large share. He is improving slowly. Dr Dickinson adds in a postscript, what is still more to the point, that the sausages would be most likely undercooked; they would be cooked in the frying-pan, and if only brown on the outside would be eaten. It is probable that the outbreak was due therefore to eating underdone meat from this pig, cooked in various ways, and not alone from the ham itself.”

If the facts connected with this outbreak be honestly faced, it must be rendered clear to any unprejudiced observer that Dr W. Lindow Dickinson was the first person to observe, recognise, and treat the Trichina disorder in this country. No other English, Scotch, or Irish physician has encountered any similar case. If I lay stress upon this fact it is because I have learned from Dr Dickinson that another person has asserted priority in this relation. Sir Dominic Corrigan is stated to have told a gentleman in the House of Commons, “that he had often met with trichiniasis in his practice in Dublin,” further averring that the disease “was quite common in many parts of Ireland.” If Sir D. Corrigan merely desired it to be understood that he had repeatedly encountered the Trichina at post-mortem examinations, then there is nothing surprising in his statement, but if, on the other hand, the disease itself has been frequently recognised in the living Irish human subject, one can only express astonishment that hitherto no single instance of the kind appears to have been recorded either in the public or professional journals.

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H._, On a supposed Species of Trichina (_T. cystica_) from the Human Bladder; in his paper on “Parasitic Forms,” in ‘Hay’s Amer. Journ. Med. Sci.,’ 1868, p. 376.--_Sanders, R._, ‘Edin. Month. Journ.,’ 1853.--_Sawer, A._, ‘Bost. Med. and Surg. Journ.,’ 1865, p. 16.--_Sutton, G._, Report on Trichinosis; Indiana, U.S., 1874.--_Thudichum, J. W. S._, ‘Brit. Med. Journ.,’ Jan., 1864, repr. in ‘Glasgow Med. Journ.,’ April, 1864, p. 116; also letter in ‘Edin. Med. Journ.,’ Feb., 1864.--_Idem_, “Rep. on the Parasitic Diseases of Quadrupeds used as Food,” pub. by the Med. Officer of the Privy Council, London, 1865.--_Idem_, “The Diseases of Meat as affecting the Health of the People,” ‘Journ. Soc. of Arts,’ April 20, 1866.--_Idem_, “German Sausages and the Trichina Disease,” ‘Scientific Opinion’ for April 25, 1866.--_Idem_, ‘Lancet’ for Jan. 6, 1866, p. 16.--_Turner, W._, “On the _Trichina spiralis_,” ‘Edin. Med. Journ.,’ Sept., 1860; in the ‘Year-Book,’ p. 109, for 1860; in ‘Med.-Chir. Rev.,’ 1862; and in ‘Bost. M. and S. Journ.,’ vol. lxiii, p. 294.--_Ude_, “Rep. on the Inspection of Pigs,” ‘Med. Times and Gaz.,’ Aug., 1868, p. 141.--_Valentin_, ‘Micr. Journ. and Struct. Rec.,’ 1842, p. 87.--_Virchow, R._, Extr. from his brochure on ‘_Trichina_’ (by myself), in ‘Gunther’s Record’ for 1864, p. 611.--_Idem_, “On the Cure of Trichinosis,” ‘Brit. Med. Journ.,’ April, 1866, p. 368.--_Idem_, from “Comptes Rendus,” in ‘Qrt. Journ. Micr. Sci.,’ 1861.--_Idem_, from his ‘Archiv,’ 1860, Bd. xviii, Heft. 4, p. 330; in ‘Brit. and For. Med.-Chir. Rev.,’ vol. xxvi, p. 515, 1860.--_Wedl_, Report, ‘Brit. Med. Journ.,’ Dec., 1866, p. 618.--_Wilks, S._, “Letter respecting the Discovery of Trichina,” ‘Lancet,’ March 10, 1866, p. 269; see also the ‘Times,’ Feb. 13, 1866.--_Windsor, J._, ‘Brit. Med. Journ.,’ March 4, 1866, p. 319.--_Wood, H._, case, ‘Lond. Med. Gaz.,’ 1835.

_Foreign Literature_:--_Ardenghi, E._, “Sulla _Trichina spiralis_,” ‘Lo Studente Veterinario,’ 1876, p. 115.--_Behrens_, “Ein Fall von Trichiniasis,” ‘Deutsche Klinik,’ No. 30, 1863 (quoted by Davaine).--_Bette, F._, _ibid._, 1876.--_Bischoff_, ‘Path. Anat. des menschl. Körp.,’ 1845.--_Idem_, ‘Med. Annalen,’ 1840.--_Böhler_, ‘Die Trichinenkrankheit in Planen,’ 1863.--_Boudin_, “Des épidémies de Trichina spiralis observées en Allemagne dans ces dernières années,” ‘Journ. de Méd. Vét. Milit.,’ August and September, 1864 (quoted by Davaine).--_Claus_, ‘Wurzb. nat. Zeitschr.,’ 1860.--_Idem_, ‘Ueber die Trichine’ (a discourse), 1877.--_Colberg_, ‘Deutsche Klinik,’ 1864.--_Davaine, C._, ‘Traité’ (l. c., Bibl. No. 1), 1860, p. 672, 2nd edit., p 732-768.--_Idem_, “Faits et Considerations sur la Trichine,” ‘Mémoires de la Société de Biologie’ for the year 1862, tom. iv, ser. 3, 1863; in ‘Gazette Médicale de Paris,’ 1863; in ‘British Medical Journal’ for April 25, 1863; and in my ‘Entozoa,’ p. 349.--_Idem_, “La Trichine” (popular exposition), in ‘Revue des Deux Mondes’ for May, 1865.--_Dujardin_ (l. c., Bibl. No. 1), p. 24.--_Fiedler_, ‘Virchow’s Archiv,’ 1864.--_Fleckles, F._, ‘Die Trichinen und die Trichinenkrankheit’ (popular exposition), Prag., 1866 (quoted by Davaine).--_Friedrich, N._, ‘Virchow’s Archiv,’ 1862.--_Fürstenberg_, “Wochenblatt d. Ann. der Landwirthsch., in d. Königl. Preuss. Staaten,” 1865.--_Gerlach, C._, ‘Die Trichinen,’ 1866.--_Idem_, ‘Hannöversche Zeitschrift,’ 1864.--_Hagen_, in ‘Pharmaceutische Centralhalle,’ 1862.--_Henle_, ‘Muller’s Archiv,’ 1835, s. 526.--_Herbst_, ‘Nachrichten v. d. Georg-Aug. Univ. zu Göttingen,’ 1852; ‘L’Institut,’ 1852, p. 135.--_Heschl, R. L._, ‘Ueber Trichinen, die Trichinenkrankheit und die Schützmassregeln dagegen,’ Gratz, 1866 (quoted by Davaine).--_Kestner_, “Etude sur le Trichina,” ‘Gaz. Méd. de Paris,’ 1864.--_Klusemann_, “Die Erkrankung durch den Genuss von Nahrungsmittel aus dem Thierreiche,” ‘Deutsche Klinik,’ 1864.--_Kobelt_, ‘Valentin’s Repertorium,’ 1841.--_Krabbe_, “Husdyrenes Indvoldsorme,” ‘Tiddsskrift for Vet.,’ 1872.--_Kratz_, ‘Die Trichinenepidemie zu Hedersleben,’ 1866.--_Küchenmeister_, ‘Parasiten,’ 1855.--_Leuckart_, ‘Untersuchungen ueber _Trichina spiralis_,’ 1866.--_Idem_, ‘Die mensch. Par.,’ Bd. ii, s. 409.--_Idem_, “Die neuesten Entdeckungen ueber menschliche Eingeweidewürmer und deren Bedeutung für die Gesundheitspflege,” ‘Unsere Zeit.,’ 1862.--_Lion_, ‘Zur Geschichte, Therapie, Prophylaxis, und Sanitätspolizei der Trichinen’ (quoted by Pagenstecher).--_Luschka_, “Zur Naturgeschichte der _Trichina spiralis_,” ‘Zeitschr. für wissenschaftl. Zool.,’ 1851.--_Meissner_, ‘Zeitschr. f. rat. Med.,’ 1855.--_Idem_, “Ueber Trichinenkrankheit,” ‘Schmidt’s Jahrbücher,’ 1863.--_Ordonez, E. L._, ‘Note sur la Distinction des Sexes et le Développement de la Trichina spiralis des Muscles,’ Paris, 1863; and ‘Compt. Rend. Soc. Biologie,’ p. 61, 1863 (quoted by Davaine).--_Pagenstecher_, ‘Verhandl. d. Naturhist.-Med. Vereins zu Heidelberg,’ 1864.--_Idem_ (und _Fuchs_), ‘Die Trichinen,’ 1865.--_Perroncito_, “La _Trichina spiralis_” in ‘Italia. Estr. degli Annali R. Accad. d’Agric. di Torino,’ vol. xx, 1877.--_Reyher, O._, ‘Die Trichinenkrankheit,’ Leipzig, 1862.--_Rodet, H._, ‘De la Trichine et de la Trichinose,’ Paris, 1865 (quoted by Davaine).--_Rupprecht, B._, ‘Die Trichinenkrankheit im Spiegel der Hettstedter Endemie betrachtet,’ Hettstedt, 1864.--_Seidel_, ‘Jenaische Zeitschr. f. Med. u. Nat.’ 1864.--_Siebert_, ‘Ueber die Trichinenkrankheit und ihre Vermeidung,’ Jena, 1863.--_Siebold_, art. “Parasiten,” ‘Wagner’s Handwörterbuch,’ 1844.--_Simon, G._, “Eine Trichinen-epidemic in Calbe,” ‘Preussische Medicinal Zeitung,’ 1862.--_Tommasi_, ‘La Trichina spiralis e la Malattia prodotta da esso,’ Torino, 1863.--_Tüngel_, ‘Archiv von Virchow,’ xxvii, 3, 421, 1863 (quoted by Davaine).--_Virchow_, ‘Deutsche Klinik,’ 1859; ‘Comptes Rendus de l’Acad. des Sci.,’ tom. xlix.--_Idem_, ‘Archiv f. Path. Anat. und Physiol.,’ Bd. xviii.--_Idem_, ‘Darstellung der Lehre von den Trichinen’ (fur Laien und Aerzte), 1864.--_Vogel_, ‘Die Trichinenkrankheit,’ 1864.--_Wagner_, “Eine Trichinenepidemie in Leipzig,” ‘Arch. der Heilkunde,’ 1864.--_Wunderlich, C. A._, “Sur la diagnose probable de l’affection trichinale,” ‘Gaz. Méd. de Paris,’ p. 311, 1863; from ‘Wagner’s Archiv der Heilkunde,’ ii, 3, p. 269, Leipzig, 1861 (quoted by Davaine).--_Zenker_, “Zur Lehre von der Trichinenkrankheit,” ‘Deutsches Archiv. für Klin. Med.,’ Bd. viii, s. 387.--_Idem_, ‘Virchow’s Archiv,’ 1855 and 1860.

_Trichocephalus dispar_, Rudolphi.--This well-known worm possesses a long filiform neck, occupying about two thirds of the entire length of the body. The surface of the skin though smooth to the naked eye is furnished on one side with a longitudinal band of minute wart-like papillæ. The tail of the male is curved, and emits at the extremity a short, tubular penis-sheath, armed with minute retroverted spines. The tail of the female is straight and bluntly pointed. The eggs measure 1/480″ to 1/447″ in their long diameter. The whipworm infests the cæcum, and also the upper part of the colon. Upwards of one thousand were found by Rudolphi in a woman.

The original name of _Trichuris_, given to this worm by Buttner, could not, of course, be allowed to stand when it became evident that the so-called tail was in reality the head and neck. The _Trichocephalus_ is not uncommon in England and Ireland. It is less frequent in Scotland. On the continent, however, it is so abundant that M. Davaine calculates that not less than one half of the inhabitants of Paris are infested by it. From what Dujardin has said it can be scarcely less abundant in Northern France, for M. Duval, the distinguished director of the Rennes School of Medicine, supplied that helminthologist with numerous specimens on various occasions. The worm abounds in Italy and Egypt; being scarcely less prevalent in the United States. The lamented Mr Noel, one of my old pupils at the Middlesex Hospital College, brought me specimens which he found post-mortem on three or four occasions. Dr Haldane, of Edinburgh, once or twice obtained large numbers (post-mortem). In Ireland, Bellingham found the worm in eighty-one out of ninety post-mortem examinations. Mr Cooper, of Greenwich, met with it, post-mortem, in eleven out of sixteen instances. When treating patients for tapeworm I have repeatedly expelled the whipworm.

The organisation of _Trichocephalus dispar_ has been investigated by Dujardin, Mayer, Von Siebold, Eberth, Bastian, and others. Prof. Erasmus Wilson and myself have carefully studied the anatomy of the closely-allied whipworm of ruminants (_T. affinis_) which is discussed in my ‘Entozoa.’

The statement of Küchenmeister that there are no external appendages in the female _Trichocephalus_ comparable to those known to exist in the allied _Trichosomata_, is incorrect. Leuckart’s, and especially Virchow’s, researches disproved Küchenmeister’s and Meissner’s notion that _Trichinæ_ were the young of _Trichocephalus_. The experiments of Davaine render it probable that the young get into the human body in a direct manner. He finds that the eggs undergo no development whilst yet lodged within the host’s intestines. The eggs are expelled per anum in the immature condition in which they first escape from the body of the parent worm. It further appears that, after their expulsion, a period of six months must elapse before embryonic formation commences. The fully-developed embryo measures 1/333″ in length, and resembles the parent to a certain extent.

Whipworms rarely put their bearers to inconvenience; nevertheless, both human and animal hosts occasionally suffer from their presence. Thus, Felix Pascal quotes a remarkable and fatal instance of cerebral symptoms from this cause in a girl of four years of age; and Mr Gibson has recorded an instance in which these worms produced paralysis and loss of speech. According to Professor Axe, sheep suffer severely from the allied species.

BIBLIOGRAPHY (No. 22).--_Bastian, H. C._, “On the Anatomy of the Nematoids,” ‘Phil. Trans.,’ 1866, p. 545.--_Bellingham, O. B._, “On the frequency of _Trichocephalus dispar_ in the Human Intestines,” ‘Rep. of Brit. Assoc., in Dubl. Journ.,’ 1838, and in ‘Med. Chir. Rev.,’ 1838; see also Bibliog. No. 33 (and the biography of Bellingham by Dr Mapother, in ‘Dubl. Jrn. Med. Sci.,’ 1877, p. 471).--_Busk, G._, “Anat. of _T. dispar_,” ‘Ann. Nat. Hist.,’ vol. vii, 1841.--_Chiaje_, sul _Tricocephalo disparo_, &c., 1836.--_Cobbold_, ‘Entozoa,’ pp. 69 and 329.--_Idem_, ‘Worms,’ pp. 31 and 67.--_Davaine_, l. c., p. 205.--_Idem_, ‘Compt. Rend.,’ 1858, p. 1217, and ‘Journ. de Physiol.,’ 1859, p. 296.--_Dubini_, ‘Entozoografia umana,’ p. 83.--_Dujardin_, l. c., p. 32.--_Eberth_, “Die Generationsorgane von _T. dispar_,” ‘Sieb. und Köll. Zeitschr.,’ 1860, s. 384.--_Gibson, D._, “On a Case of Paralysis, with loss of speech, from intestinal irritation (produced by _T. dispar_),” ‘Lancet,’ Aug. 9th, 1862, p. 139.--_Goeze_, ‘Naturg.,’ s. 112.--_Gurlt_, ‘Path. Anat.,’ p. 350.--_Küchenmeister_, l. c., s. 235; Eng. edit., p. 321.--_Leidy_, ‘Proc. Acad. Phil.,’ viii, p. 53.--_Leuckart_, l. c., s. 465.--_Mayer_, Sieb. und Köll. ‘Zeitsch. f. wiss. Zool.,’ Bd. ix, s. 367; Bd. x, s. 233, and s. 383, 1858-60.--_Mérat_, ‘Dict. Sc. Méd.,’ p. 560.--_Von Siebold_, ‘Wiegm. Arch.,’ 1845.--_Wilson, E._, ‘The Veterinary Record and Trans.,’ vol. ii, p. 47, 1846.

_Filaria Bancrofti_, Cobbold.--The history of the discovery of this entozoon is second only in interest to that of _Trichina spiralis_. Step by step the facts have been evolved by a slow process of observation, and from the data thus afforded a tolerably connected narrative of the probable life-cycle of this entozoon may now be offered. To place matters beyond all doubt much remains to be done; yet that which has been accomplished is, or ought to be, of surpassing interest alike to the physician, the scientific pathologist, the epidemiologist, and the philosophic naturalist. In the case of Trichina, Owen’s nomenclature was most properly allowed to stand; but for reasons stated below I have not hesitated to employ for this worm, in its adult state, a name differing from that originally given to the hæmatozoon which turns out to be its representative larval state. Although the male parasite is at present unknown, the following characters will in the meantime suffice for a diagnosis of the species:--Body capillary, smooth, uniform in thickness. Head with a simple circular mouth, destitute of papillæ. Neck narrow, about one third of the width of the body. Tail of female simple, bluntly pointed; reproductive outlet close to the head; anus immediately above the tip of the tail. Length of largest females, 3-1/2 in.; breadth, 1/90″; embryos, 1/200″ to 1/125″ in length, by 1/3000″ to 1/2250″ in breadth; eggs, averaging 1/1000″ by 1/1650″ from pole to pole.

The first discovery of this entozoon, in its embryo state, was made by Wucherer on the 4th of August, 1866. To use Dr Da Silva Lima’s words:--“At the moment when Wucherer was seeking for the _Bilharzia hæmatobia_, he found instead of it an unknown worm. Our illustrious collaborator,” adds Dr Lima, “has made his important discovery known under the modest title of ‘Preliminary Notice on a species of Worm at present not described;’ and still more modestly Wucherer formulated in the following manner his judicious and prudent conclusions:--It would be rash on my part to put forth a conjecture on the coexistence of these worms of the hæmatochyluria, and on the etiological signification which they might have. I shall therefore abstain until I have been able to make more ample investigations, and until I have been permitted to examine the corpse of a hæmaturic, which has not yet been possible.” (‘Gazeta Medica da Bahia,’ Dec., 1868, p. 99.)

In the year 1868 Dr J. H. Salisbury referred certain ova which he found in the urine to a new and distinct species of nematode. Although he had no acquaintance with the adult parasite, Dr Salisbury at once placed the “species” in the genus Trichina. Here is what he says:--“_Trichina cystica_ (Salisbury).--This is a small species which I have found in the human bladder. In all my examinations I have met with this little entozoon in three cases only. In two of these it was only occasionally met with in the urine. In the other it occurred in great numbers. Frequently from ten to fifteen ova were found in a single drop of urine.”

It is important to remark, that there was no hæmaturia in the last-named case, which Dr Salisbury describes as one of “cystinic rheumatism,” or “severe cystinæmia associated with rheumatism and paralysis.” The patient “had been insane for several years. Her urine was passed milky, with granular cystine, and was dense and scanty.” It is likewise added: “No examination was made of the muscles after death to determine whether this species burrowed in the tissue, like the (_Trichina_) _spiralis_.”

So much for the principal facts recorded by Dr Salisbury. His paper is accompanied by two woodcut figures of the ova (× 300 diam.), and one representation of the embryo (× 1000 diam.). If these figures give the size correctly, the ova measure only about 1/800″ in length, by 1/1560″ in breadth, whilst the embryo would be about 1/500″ from head to tail.

On the 17th of May, 1872, I communicated to the Metropolitan Counties Branch of the British Medical Association a paper on ‘_Bilharzia_,’ and in an Appendix to it I wrote as follows:--“A most interesting circumstance connected with this case of ‘_Bilharzia_’ from Natal lies in the fact that I obtained from the patient some other urinary parasites in the egg-condition (fig. 38). On five separate occasions I obtained one or more specimens of the eggs or embryos of a minute nematode. In one instance there were about fifty of these ova in the urine, their contained embryos being well developed and in a state of activity. Usually they were all in this advanced condition; but on the 25th of July, 1870, several were observed in much earlier stages of development. One of these was of a triangular form; its shape, granular contents, and clearly defined limiting membrane, indicating separation from the rachis within the ovarian tube. Another early form was perfectly spherical, with a well marked chorional envelope and double contour. These forms measured about 1/750″ in diameter. The fully grown eggs observed at the same time gave a longitudinal measurement of 1/500″ by 1/1000″ in breadth. On adding any stimulus, such as diluted sulphuric acid, the embryos moved themselves freely within the egg. After allowing the urine to stand for forty-eight hours, I found, on the 27th of July, that the shells of the ripe ova had dissolved, leaving the embryos dead, but still coiled within a fine transparent envelope. In this state they were easily separated and examined, when they gave a measurement of 1/300″ in length, by 1/3500″ in breadth. On two occasions, whilst engaged in rearing the larvæ of _Bilharzia_ in water, I noticed single specimens of these embryos lying dead; and one of the examples thus observed gave a length of 1/150″, by 1/3000″ in breadth.”

Knowing what errors of interpretation have often crept into helminthological literature I was more than usually cautious in pronouncing upon the source of these urinary parasites. Accordingly, I remarked that “future discoveries might enable us to identify the species of nematode to which these ova are referable.” I also added:--“Notwithstanding discrepancies as to size, I am inclined to think that Dr Salisbury and myself have been made acquainted with nematode eggs and embryos referable to one and the same species of parasite. I do not care to speculate as to the origin of these ova. Long ago I gave in my adhesion to the determinations of Schneider in respect of the so-called _Spiroptera hominis_, but I am by no means certain that his position may not be disturbed by fresh discoveries. It is not a little remarkable that the parents of my patient should have averred that she passed three small vermiform entozoa by the urethra, corresponding, to judge from their verbal statements, very closely with the ordinary appearances of _Filaria piscium_.”

Having written thus much seven years back, it is with natural pleasure that I find my anticipations already verified. Knowing that I was dealing with parasites in their earliest larval stages, it never occurred to me to give a specific name to them, and I could not possibly approve of Dr Salisbury’s nomenclature, for which there was no good ground.

In the original discovery Dr O. Wucherer procured the worms from the chylous urine of a female in the Misericordia Hospital at Bahia; and on the 9th of the following October, 1866, he obtained similar worms from another female suffering from hæmaturia. He also afterwards found them in a man whose urine was slightly chylous, but not hæmatic. In all cases these sexually-immature nematodes were alive. In September, 1872, Dr A. Corre furnished a careful description of similar worms found by Dr Crévaux in a hæmato-chylurous patient at Guadeloupe. Dr Crévaux frequently examined the blood of this patient but found no hæmatozoa. In like manner in Brazil, Dr J. Silva Lima sought in vain for worms in the blood of no less than five patients, all of whom suffered from hæmaturia, and whose urine contained numerous nematoid worms.

Towards the close of the year 1872 the biological world was startled by the announcement of the discovery of minute Filariæ in human blood. Dr T. R. Lewis had found microscopic worms in the blood, and also in the urine, of persons suffering from chyluria. The worms could be obtained from day to day by simply pricking any portion of the body with a finely pointed needle. To this hæmatozoon Lewis gave the trinomial term _Filaria sanguinis hominis_, which thus fitly distinguished it from the _Filaria papillosa hæmatica canis domestici_ described by Grube and Delafond. Dr Lewis found the average size of the parasite to be 1/75″ in length by 1/3500″ in breadth. He observed that while it exists in the blood the body is enclosed in a delicate transparent tunic or cyst. The worm was never absent from urine in chyluria. In a case in which there was a milky discharge from the eyes the worms were also detected. In one case Lewis calculated that 140,000 Filariæ were present in the blood--a number certainly not relatively large seeing that MM. Grube and Delafond estimated the verminiferous blood of their several dogs to contain numbers varying from 11,000 to 224,000. Lewis also found Filariæ in the kidneys and supra-renal capsules of a woman who died of chyluria. It did not appear probable that the worms underwent further development in the human body. On this point Lewis remarks:--“Not only may those hæmatozoa found in man live for a period of more than three years, but there is no evidence that they have any tendency to develop beyond a certain stage as long as they remain in the circulation.” Dr Lewis judged that the form of chyluria associated with this condition of the blood was local and intimately related with a tropical climate. The milky condition of the urine comes on suddenly, not only at first, but on succeeding occasions also. It is frequently accompanied by more or less distinctly marked symptoms of various other obscure diseases, including temporary swellings in the face or extremities. From certain appearances of intestinal ulceration Lewis thought that the parasites might gain access to the system by the alimentary canal, possibly from the tank-water or the fish inhabiting it. He considered the state of the urine to be due to the mechanical interruption offered to the flow of the nutritive fluids of the body. The accidental aggregation of the Hæmatozoa might give rise to obstruction of the currents within the various channels, or occasion rupture of their extremely delicate walls, and thus cause the contents of the lacteals, lymphatics, or capillaries, to escape into the most conveniently placed excretory channel.

Compressed into a small compass, I think the above is a fair statement of the leading facts and phenomena discovered by Lewis. The whole subject of hæmatozoology immediately received additional impulse, the consequences of which have not yet terminated. In this country Welch was stimulated to investigate the structure of _Filaria immitis_ in the dog, whilst others sought diligently for nematoid hæmatozoa abroad.

On the 20th of April, 1874, Dr Prospero Sonsino communicated to the Neapolitan Royal Academy his memoir entitled “Researches concerning _Bilharzia hæmatobia_ in relation to the endemic hæmaturia of Egypt, with a notice concerning a nematoid found in the human blood.” In this brochure he made known the fact of his having discovered microscopic Filariæ in a young Egyptian Jew, in the following words:--“On the 1st of February last, having well washed the finger of the boy, I placed one drop of blood under the microscope, when with astonishment I discovered a living organism of the form of a nematode, resembling _Anguillula_, in the midst of the hæmatic corpuscles. The worms glided amongst the globules, which were tossed about by their lively movements, showing various appearances according as they presented themselves either from the sides, the edges, or the front of the disk” (‘Ricerche,’ &c., pp. 11, 12). Dr Sonsino took every precaution to prevent error, subsequently verifying his “find” from the same patient. Dr Sonsino directs attention to two of his own characteristic figures of the worm, and subsequently states not only that he found examples of the Filariæ in the urine of this same youth, but also “in the urine of another patient.” The parasites from these two sources being figured side by side, it was clear, from their resemblance, that they referred to one and the same species of entozoon. Dr Sonsino having compared the facts supplied by these cases, was satisfied that the nematodes in question were specifically identical with those that I had previously obtained from my little African patient. However, Dr Sonsino was of opinion that his Filariæ were not precisely the same as those that had been described by Lewis.

On the 8th of April, 1876, I received from Dr William Roberts, of Manchester, some capillary tubes, charged with blood, obtained from a patient suffering from chyluria. The tubes had been transmitted by Dr Bancroft, of Brisbane, Queensland, Australia; and in fulfilment of the donor’s request, Dr Roberts afforded me an opportunity of examining their contents, he having himself verified Bancroft’s statement that they contained Filariæ. It was not until May 22nd that I found opportunity to confirm the observations of Drs Bancroft and Roberts. The contents of some of the tubes had by this time completely dried up; but in others, to which diluted glycerine had been added, the blood appeared tolerably fresh. In what might be reckoned as the sixth part of the contents of one of the tubes, spread on a glass slide, I detected about twenty Filariæ, three of which I sketched _in sitû_, in order to compare them with the figures of Lewis, and also with others that I had procured from my _Bilharzia_-patient in the year 1870. There could not, I thought, be any doubt as to the identity of all these sexually-immature nematoids. One novelty, however, presented itself in the presence of a solitary and empty egg envelope, measuring about 1/500 of an inch in its long diameter, and thus corresponding precisely with the ova that I obtained from the urine in my _Bilharzia_ case.

According to Bancroft, chyluria is somewhat common in Brisbane; and the case here brought forward was not the only one of the kind which had already furnished Filariæ in the blood. The patient was a little girl ten years of age.

Thus stood the facts in the spring of 1876. Having informed Dr Bancroft that a nematoid egg had been detected in the Australian blood transmitted to England, he was induced to make further investigations. These happily resulted in the discovery of the adult worm; the circumstances attending the “find” being recorded by Dr Bancroft in a letter written to myself and dated from Brisbane, Queensland, April 20th, 1877. He wrote as follows:--“I have labored very hard to find the parental form of the parasite, and am glad to tell you that I have now obtained five specimens of the worm, which are waiting to be forwarded by a trustworthy messenger.

“I have on record about twenty cases of this parasitic disease, and believe it will be the solution of chyluria, one form of hæmaturia, one form of spontaneous lymphatic abscess, a peculiar soft varix of the groin, a hydrocele containing chylous fluid, together with some forms of varicocele and orchitis. These I have verified. In the colony there are no cases that I can find of elephantine leg, scrotal elephantiasis, or lymph scrotum; but from the description of these diseases in the volume on skin and other diseases of India by Fox, Farquhar, and Carter, and from Wm. Roberts’ article on the latter in his volume on urinary diseases, I am of opinion that the parasitic nature of the same will be established.

“The worm is about the thickness of a human hair, and is from three to four inches long. By two loops from the centre of its body it emits the Filariæ described by Carter in immense numbers.

“My first specimen I got on December 21st, 1876, in a lymphatic abscess of the arm; this was dead. Four others I obtained alive from a hydrocele of the spermatic cord, having caught them in the eye of a peculiar trochar I use for tapping. These I kept alive for a day and separated them from each other with great difficulty. The worm when immersed in pure water stretches itself out and lies quite passive. In this condition it could be easily washed out of hydroceles through a large-sized trochar from patients known to suffer from Filariæ.”

In July, 1877, I announced Bancroft’s discovery in the ‘Lancet,’ naming the parasite _Filaria Bancrofti_, and in the following September I sent the editor an account of the results of my study of the adult worms received from Brisbane in the interval. These examinations supplied me with the diagnosis already given (p. 181).

On the 29th of September, 1877, Dr Lewis published a paper in the ‘Lancet,’ wherein, after alluding to my previous announcement respecting the discovery of _Filaria Bancrofti_, he describes under the name of _Filaria sanguinis hominis_ a mature worm, which was evidently the same parasite. Not unnaturally Dr Lewis put aside the nomenclature I had employed, on the ground that the name originally given by himself to the embryonal form ought to be retained, and that “a new name, if not necessary on anatomical grounds, would only lead to confusion.” Personally I have no objection to Lewis’s specific name, but if the question of priority is to determine the nomenclature, then I fear we ought to call the species _Filaria Salisburyii_. Obviously the retention of Dr Salisbury’s nomenclature (_Trichina cystica_) would be unsuitable and misleading.

When (prior to Lewis’s discovery of the hæmatozoa) I had myself encountered larval nematodes of the same character as those described by Salisbury, I, like Wucherer, was careful not to employ a special name for an immature form, which might or might not represent a worm hitherto known to science. The paper in which I described the adult worm from specimens supplied by Bancroft appeared in the ‘Lancet,’ Oct. 6th, 1877, the facts being stated as follows:--

On the 28th of August, 1877, I received a small collection of entozoa. The box contained the promised Filariæ, and also eight bottles filled with various intestinal worms taken from animals. The Filariæ were enclosed in four small tubes and preserved in glycerine. Three of the tubes (marked 1, 2, 3) contained sexually-mature worms, the fourth being labelled “Sediment from adult _Fil. sang._--young and ova.” I described their contents in succession. Thus, on the 6th of September, 1877, I examined the Filaria in tube No. 3. The specimen was injured and in four portions, these collectively measuring three inches in length. Although, to the naked eye, the worm had appeared to Dr Bancroft to be of the thickness of an ordinary human hair, yet I found it about 1/90″ at the thickest part. It was a female. At the same time I examined the specimen in tube No. 1. This was also a female. Towards the centre of the body a hernial protrusion of the uterine horns and intestine had taken place. In a lithograph sent by Dr Bancroft this specimen was figured and described as the “parent worm of the _Filaria sanguinis_, emitting young Filaria from two loops.” Later on I examined the contents of tube No. 2. In it I found one tolerably perfect female Filaria, and also a delicate shred forming part of one of the uterine horns of another worm. This filament measured one inch and a half in length, and was coiled round the complete worm. On transferring it to a watch-glass containing water, hundreds of embryos made their escape. Owing to the transparency of the tissues I had much difficulty in finding the reproductive outlet, and the effort to find it was all the greater because Bancroft’s figure had misled me. At length I found the vagina and its orifice close to the head (about 1/20″ from it), the anal orifice being placed within the 1/90″ from the extremity of the tail. The vaginal pouch, 1/100″ long, was crowded with embryos, and a constriction marked its junction with the uterus proper, which appeared to divide lower down at a distance of 1/10″ from the head. Towards the tail a fold of the tuba Fallopii was seen to extend to within 1/20″ of the extremity. All sections of the uterine system were crowded with germs, eggs, and embryos in their usual relative situations.

My examinations of the ova and embryos were chiefly made from the “sediment” sent in a special glass tube. The fully formed embryos were 1/125″ in length by 1/2500″ in breadth. They each showed a double skin, the outer envelope in the more advanced specimens leaving clear spaces at either end of the body, resulting from commencing ecdysis. I saw no trace of intestinal tube, but a central line of condensation marked an early differentiation of the somatic granular contents. The less advanced embryos were mostly enclosed in a chorional envelope, the smallest free embryos measuring only 1/200″ in length by 1/3000″ in breadth. These had no double contour. The ova, whose yolk-contents were still in various stages of cleavage, gave an average long diameter of 1/900 to 1/1000 of an inch.

Such are the facts I made out, and they enabled me to amend the characters of the species.

As regards nomenclature, I associated Dr Bancroft’s name with the sexually-mature worm as being in harmony with the binomial method and little calculated to mislead; moreover, it helped to fix both the source and date of the discovery (Brisbane, Dec. 21st, 1876). The use of this nomenclature detracts nothing from the high merits of Lewis, who first named the immature worm _Filaria sanguinis hominis_. As it now turns out, both Dr Salisbury and myself had previously been made acquainted with the young of _Filaria Bancrofti_; but it was reserved for Lewis to discover the hæmatozoal character of the embryos of this worm, and actually to take them from the blood. It was a singular circumstance, that when I was engaged in treating my little African patient for trematode hæmatozoa, it never once occurred to me that the numerous nematoid embryos mixed with the Bilharzia ova were hæmatozoal. As before remarked, it was alleged that my patient had passed worms two or three inches long by the urethra. I therefore concluded that these were the parents of the eggs and embryos, and that all of them were urinary. The inference was wrong, but it has instructively shown how near one may go towards a great discovery without really making it. As regards the larvæ, notwithstanding some slight differences in regard to size and so forth, I have little hesitation in saying that all the embryo forms severally described by Salisbury, by myself, by Lewis, Sonsino, Wucherer, Crévaux and Corre, Silva Lima, Bancroft, Manson, and others, are referable to one and the same species.

Into the clinical bearings of this subject it is impossible for me to enter at any length, but I may remark that these parasites appear to be associated with, if not actually the cause of, several distinct morbid conditions. To one of these Bancroft has given a separate name (_Helminthoma elastica_). This is a highly elastic form of growth to which I have already alluded under the title of “lymphatic abscess of the arm.” In the first valuable report on Hæmatozoa, by Dr Patrick Manson, of Amoy, China, this careful observer gives interesting particulars of no less than fifteen cases in which hæmatozoa were found. Two of these patients had _Elephantiasis scroti_, two had lymph-scrotum, two were lepers (one having scrotal disease), two had enlarged inguinal glands, one had anasarca; and of the remaining six, spoken of as having no concomitant disease, one had enlarged glands and abscesses, and another suffered from marked debility. It would thus appear that what is ordinarily termed “good health” is rarely associated with a hæmatozoal condition of the blood in the human subject. The cases given by Lewis and Manson, where absolutely no recognisable disease existed, must be regarded as exceptional. Disease, moreover, may exist without any palpable symptoms being exhibited by the “bearer,” and thus perhaps it was with the hæmatozoal dogs of Gruby and Delafond to which I shall again have occasion to allude. Even those animals that carried upwards of two hundred thousand microscopic Filariæ in their blood appeared to suffer no inconvenience whatever.

In the autumn of 1877 Dr Da Silva Lima published an article in the ‘Gazeta Medica da Bahia,’ in which he dwelt upon the labors and merits of Wucherer, and, judging from an omission in one of my memoirs, he supposed that I had insufficiently acknowledged Wucherer’s claims. A translation of this article appeared in the ‘Archives de Médicine Navale,’ with an important appendix by Dr le Roy de Méricourt. In this _addendum_ the French _savant_ showed that the omission on my part was unintentional, and had been corrected by me in a later memoir. Not only had I been amongst the earliest in England to enforce Wucherer’s claims in respect of the micro-Filariæ, but I had first announced his discoveries in connection with _Anchylostoma duodenale_. In my translation of Wucherer’s memoir (‘Ueber die Anchylostomum Krankheit’) I spoke of the melancholy satisfaction I had in knowing that the memoir in question was “among the last that appeared from the pen of that gifted and amiable physician.” Some notice of Dr Lima’s paper and its appendix by Dr A. le Roy de Méricourt appeared in the ‘Lancet’ for Jan. 5th, 1878, and I also published a full translation of it, with explanatory notes, in the ‘Veterinarian’ for Feb., 1878. Later on, in the ‘Lancet’ (March 23rd, 1878), Dr Da Silva Lima published an interesting letter correcting a misconception that had incidentally arisen in the mind of a commentator (on the Helminthological work of 1877), and at the same time he pointed to the original facts connected with the discovery of Wucherer’s Filaria. As my views are in perfect accord with those of Dr Da Silva Lima, I can only regret that errors of interpretation should have crept into the discussion. Dr Lima honorably recognises the nomenclature (_Filaria Bancrofti_) which I proposed for the adult worm, and only claims for Wucherer that which is fairly due.

On the 4th of January, 1878, I received from Dr Patrick Manson a manuscript in which he announced the discovery of the larvæ of _Filaria sanguinis hominis_ in the stomach of mosquitoes. Already, in April, 1877, Dr Bancroft had informed me of his expectation of finding that these insects sucked up the larvæ of the Filaria whilst engaged in their attacks on man. Dr Bancroft’s supposition was a very natural one, but it remained for Manson to make the actual discovery of the existence of human hæmatozoa, or parasites that had been such, within the stomach of _Culex mosquito_. I lost no time in making the principal facts public (‘Lancet,’ Jan. 12th, 1878). Dr Manson at the same time forwarded for publication a record of thirty-five additional cases of hæmatozoa occurring in Chinese subjects, together with additional particulars of one of the cases already published in the ‘Customs Gazette.’ These were afterwards published as separate contributions in the ‘Medical Times and Gazette.’ Dr Manson likewise forwarded materials for a paper entitled “Further Observations on _Filaria sanguinis hominis_.” In this communication he gave an analysis of the cases (sixty-two in all) in which he had observed the hæmatozoa, and he added valuable statistical evidence as to the prevalence of Filariæ in the Amoy district, dwelling especially on the influence of age, sex, and occupation in determining the presence of the parasite. He also described the morbid states with which these entozoa were commonly associated.

On the 7th of March, 1878, I formally communicated to the Linnean Society a detailed account of Manson’s investigations relating to the metamorphoses undergone by the Filariæ within the body of the mosquito. In this paper Manson pointed out that the female mosquito, after gorging itself with human blood, repairs to stagnant water for the purpose of digesting the blood, and also for the purpose of depositing its eggs. During this period, which lasts four or five days, the Filariæ undergo remarkable changes. Subsequently, in a more perfect state, they escape into the water, and in this advanced stage they are conveyed to the human body along with the water as drink. Dr Manson persuaded a Chinese, whose blood was previously ascertained to abound with Filariæ, to sleep in a “mosquito house.” In the morning the gorged insects were captured and examined under the microscope. A drop of blood from the mosquito was found to contain 120 Filariæ, but a drop taken from the man’s hand yielded only some thirty specimens. Further stages of development are accomplished within the human host, ending in the sexual maturity of the parasite. After fecundation successive swarms of embryos are discharged by the female worm, a part of whose progeny eventually gains access to the blood.

Before I proceed to summarise the whole body of facts I must in the next place state that Manson and myself contributed a joint communication to the Medical Society of London on the 25th of March, 1878. In this memoir I especially dealt with the question of priority in connection with the discovery of the adult worm. I then restated that the adult parasite was discovered by Dr Bancroft on December 21st, 1876. The discovery was verified by Dr Lewis on August 7th, 1877, by Dr Silva Araujo October 16th, 1877, and by Dr F. dos Santos November 12th, 1877. I gave these dates unhesitatingly, without, however, in any way prejudicing the question already raised in respect of the identity of the worms found in each case. My own mind was fully made up on that point, and affirmatively so. Dr dos Santos’ find was made in conjunction with Dr J. de Moura in a case of lymphatic abscess of the arm. Clinically viewed, the case published by Dr Araujo must be regarded as unique. Not only were adult and embryonic Filariæ found in the same patient, but, what was far more surprising and interesting, the patient displayed in his own person several of the disorders hitherto found apart; and he was more than once attacked by one or two of the diseases. He experienced a first attack of chyluria three years ago, then attacks of craw-craw commencing a year ago, the latter being attributed to bathing in a particular lagoon. He had a second attack of chyluria six months back, at which time lymph-scrotum appeared, and also scrotal elephantiasis. Dr Bourel-Roncière pronounced this case to be unique, and attributed nearly all the disorders to the presence of Wucherer’s embryonic Filariæ. In a very elaborate analysis of and commentary on Dr da Silva Lima’s second memoir, Dr Bourel-Roncière warmly claims for Wucherer the supreme honor in all these discoveries. A number of affections hitherto regarded as distinct, and all of which appear to be due to the action of Filariæ, are regarded by Dr Bourel-Roncière as mere phases of one and the same disorder. This affection he terms _Wucherer’s helminthiasis_. Dr Manson had indeed arrived independently at a similar conclusion, and I am confident that Wucherer, were he alive, would in this particular aspect of the question be the last to claim priority either to Lewis, to Bancroft, or to Manson.

In this place I may observe that Dr Pedro S. de Magalhães, of Rio de Janeiro, detected free microscopic nematodes in the potable waters of Rio (agua da Carioca), which from their similarity he supposes may have some genetic relation with _Filaria Bancrofti_. In this opinion I cannot share.

As regards the metamorphoses of the embryo, Manson states that for a little while after gaining access to the stomach of the mosquito the embryo undergoes no change (Fig. 40, _a_). In a very few hours changes commence, resulting in wider separation of the outer skin and an appearance of transverse markings on the body within (_b_). In the next stage oral movements occur; the striation becomes more marked, and the outer envelope is cast off (_c_). Then the striated lines disappear and a dotted appearance is substituted (_d_). From this condition the embryo passes to what Manson calls the chrysalis stage, in which nearly all movement is suspended and the large spots gradually disappear (_e_, _f_, _g_, _h_, _i_, _j_, _k_). The tail continues to be flexed and extended at intervals and the oral motions cease. By the close of the third day the embryo becomes much shorter and broader; but the finely pointed tail retains its original dimensions, projecting abruptly from the sausage-shaped body (_m_, _n_). Large cells next appear in the interior of the body, and by a little pressure one may detect indications of a mouth (_o_, _p_, _q_, _r_). At this period the embryo begins to elongate, and at the same time to diminish in width; but the growth takes place chiefly at the oral end of the body. The mouth becomes four-lipped, open, and funnel-shaped, and from it a delicate line can be distinctly traced passing to an opening near the caudal extremity, the tail itself gradually disappearing (_s_, _t_). Speaking of the most advanced stage Manson says:--“A vessel of some sort is seen in the centre running nearly the whole length of the body and opening close to one extremity. This end is slightly tapered down and is crowned with three or perhaps four papillæ, but whether this is the head or tail, and whether the vessel opening near it is the alimentary canal or the vagina, I cannot say.” Now it is quite evident, I think, from Manson’s figures that he has here faithfully represented the head and tail, the former (_u_) to the left, the latter (_v_) to the right. In his _manuscript_ (from which I am now quoting) there is no special reference to these two figures; but it is easy to see that these terminal sections of the body of the advanced embryo closely correspond with the head and tail of the adult worm (_Filaria Bancrofti_). The curved line passing to the left (_u_) evidently indicates the commencement of the partially-formed vagina.

How completely Manson took the initiative in this part of the work is evident even from Lewis’s own later observations. In a paper published in March, 1878, Dr Lewis, writing from Calcutta and speaking of the rôle of the mosquitoes, says:--“I had repeatedly examined, in a cursory fashion, these and other suctorial insects, but had not observed any parasites suggestive of these embryo-hæmatozoa, hence, when, on receipt of a communication from Dr Manson a couple of months ago, a renewed search was made, I was surprised to find that four out of eight mosquitoes, captured at random in one of the servants’ houses, harboured specimens of hæmatozoa to all appearances identical with those found in man in this country. After this, however, several days elapsed before any mosquitoes could be obtained which contained these embryo-nematoids, and the specimens obtained on the next occasion were devoid of the enveloping sheath, which appears to characterise the kind found in man out here, and apparently, according to Dr Manson, in China also.” Further on Lewis also remarks, “When the insect is caught shortly after feeding and the contents of its stomach examined microscopically, the hæmatozoa, if present, will be observed to manifest very active movements, which may possibly continue for several hours on the slide. If the insect be kept for twenty-four hours before examination it is probable that the movements of the parasites will be more sluggish, and their form probably altered owing to irregular contractions and dilatations of their substance--changes which may also occasionally be observed when embryo-hæmatozoa are preserved on a glass slide, and they may sometimes be kept alive thus, if in suitable media, for two or three days. When the insect is not examined till the third day, the contained parasites will probably manifest marked signs of disintegration--and possibly every indication of life will have disappeared from many of the specimens. After the third or fourth day I have not seen any active specimens of these entozoa in the stomach or in any part of the alimentary canal of the mosquito; those which remain have undergone more or less fatty degeneration, and are readily stained with eosin, which, as far as my experience goes, is not the case so long as they are alive and active. After the fourth or fifth day it is very rare that traces of any hæmatozoa-like objects can be detected at all, so that it must be inferred either that they have succumbed to the digestive action of the insect’s stomach or been disposed of along with the excreta.” An important _addendum_ by Lewis records a fortunate incident as follows:--“It was observed that nearly all the mosquitoes captured in one of the servants’ houses contained hæmatozoa, so that the supply of suitable insects in all the stages of their growth became amply sufficient for all requirements. The result of the examinations under these favorable conditions has shown that although the stomach digests a great number of the ingested hæmatozoa, as mentioned above, nevertheless others actually perforate the walls of the insect’s stomach, pass out, and then undergo developmental stages in its thoracic and abdominal tissues.”

I may here observe that Sonsino has instituted a comparison between the embryos of this Filaria and those of Anchylostoma, by which it appears that the former measure 0·218 to 0·330 mm. in length, and those of Anchylostoma 0·430 mm. The hæmatozoa are about forty times longer than broad, and the larval anchylostomes only fourteen times longer. The tail of _Filaria_ is conspicuously longer.

In the ‘Lancet’ for June 22nd, 1878, an announcement appeared from the pen of Mr D. H. Gabb, of Hastings, stating that a patient under his care formed the habitat of _Filaria sanguinis hominis_; and in the autumn of the same year a paper which I read to the Linnean Society in the spring was published. In that paper the following summary was offered:

1. _Filaria Bancrofti_ is the sexually-mature state of certain microscopic worms hitherto obtained either directly or indirectly from human blood.

2. The minute hæmatozoa in question--hitherto described as Wucherer’s Filariæ, _Filaria sanguinis hominis_, _Trichina cystica_, _Filariose dermathemaca_, and so forth--are frequently associated with the presence of certain more or less well-marked diseases of warm climates.

3. The diseases referred to include chyluria, intertropical endemic hæmaturia, varix, elephantiasis, lymph scrotum, and lymphoid affections generally, a growth called _helminthoma elastica_, a cutaneous disorder called craw-craw, and also leprosy.

4. It is extremely probable that a large proportion, or at least that certain varieties of these affections are due to morbid changes exclusively resulting from the presence of _Filaria Bancrofti_ or its progeny within the human body.

5. It is certain that the microscopic hæmatozoa may be readily transferred to the stomach of blood-sucking insects, and it has been further demonstrated that the digestive organs of the mosquito form a suitable territory for the further growth and metamorphosis of the larval Filariæ.

6. The character of the changes undergone by the microscopic Filariæ, and the ultimate form assumed by the larvæ whilst still within the body of the intermediate host (_Culex mosquito_), are amply sufficient to establish the genetic relationship as between the embryonal _Filaria sanguinis hominis_, the stomachal Filariæ of the mosquito, and the sexually-mature _Filaria Bancrofti_.

In the month of September, 1878, I received a letter from Dr da Silva Lima announcing the fact that Dr Araujo had verified the existence of the embryos of _Filaria Bancrofti_ in mosquitoes, at Bahia. These mosquitoes had, I understood, attacked a French priest in whose blood Dr Araujo also detected Filariæ. Thus, it fell to the lot of Araujo, through his untiring zeal, to verify in Brazil all the separate discoveries of Bancroft, Manson, and Lewis.

In the October issue of the ‘Pathological Society’s Transactions’ for 1878 Dr Bancroft records numerous cases of filarious disease, and he gives a succinct account of the circumstances connected with his original discovery.

In a clinical lecture published October 12th, 1878, Dr Tilbury Fox seeks to diminish the value of these discoveries, characterising helminthological investigators as merely “recent writers.” Dr Fox denies that Filariæ are a cause of true elephantiasis, but admits the occurrence of “elephantoid inflammation and inflammations due to Filariæ.” Dr Fox’s statement that “Filariæ have not been found in uncomplicated elephantiasis, that is, in disease without chylous exudation,” seems to me to be directly at variance with Manson’s recorded experiences. I hold that Manson has confirmed the truth of Lewis’s views, and that he has thoroughly proved that (to use his own words) “varicose groin glands, lymph scrotum, elephantiasis, and chyluria are pathologically the same disease.” In the first instance I was myself led to conclude that some of the forms of elephantiasis might be due to other causes than obstruction of the lymphatics caused by the presence of Filariæ; but the explanations of Lewis, of Bancroft, and of Manson more especially, have almost entirely removed this doubt. Those who seek to explain away the connection between genuine elephantiasis and Filariæ will do well to study Manson’s last important memoir. He shows that “elephantiasis and allied diseases are much more frequently associated with the parasite than are other morbid conditions.” This fact is brought out very clearly in his table of 670 cases, from which it appears that 58 per cent. of cases of Filaria are associated with elephantoid disease.

When this opposition to Manson’s views is likely to cease (on the part of those who do not happen to have been in any way instrumental to the discoveries in question) it is not easy to say. In a brief communication which appeared in the last number of the ‘Medical Times and Gazette’ for 1878, Dr Manson successfully combats the doubts that have been entertained respecting the rôle of the mosquito. Because Lewis found that canine hæmatozoa were digested, and thus perished in the stomach of mosquitoes, it had been argued that _human_ hæmatozoa must necessarily undergo similar processes, and consequently die. Those who oppose the views of helminthologists in respect of the intermediary host-function of insects on such grounds can have very little general, and still less special knowledge of the phenomena of parasitism. It is the old story. When any new discovery is made, it must always pass through the ordeals of denial and doubt before it can be generally accepted as true; and, as in the case of Jenner’s immortal discovery, there will always remain a certain number of peculiar people who show themselves hostile to every advance in science. Dr Manson may take comfort from this consideration, and rest assured that the value of his discovery is quite unaffected by the opposition referred to.

Since I communicated the results obtained by Manson, Lewis, myself, and others to the Linnean Society, an even more exhaustive summary of the facts has been published by Dr Bourel-Roncière, in the ‘Archives de Médecine Navale.’ The distinguished author does full justice to the writings of English helminthologists, and dwells, with emphasis, upon the finds and interpretations of Lewis, Manson, and Bancroft. Incidentally, also, he comments upon Sir Joseph Fayrer’s early recognition of the etiological identity of hæmato-chyluria and elephantiasis, on other than helminthic grounds. The frequent concurrence of the two affections had especially struck Sir J. Fayrer as pointing to a probable common origin. He had also surmised that the disorders might be due to parasites.

Dr Bourel-Roncière, alike with the caution, precision, and logical reasoning of a cultured _savant_, concludes his elaborate review in the following terms:--“There are the facts. Certainly, many points remain obscure, many problems await a solution, and the last word has not been said on the actual part which the parasite plays in the pathogenesis of the affections above enumerated--its mode of action, the importance of its rôle, the extent of its pathological domain, the habitat of its progenitors, their identity, and so forth. All these questions will only be elucidated by necroscopic researches, which at present remain absolutely wanting.”

“However, notwithstanding the doubts which hover over the future value of these curious discoveries, it is difficult not to recognise their importance in the study of certain tropical diseases--which up to the present time have been attributed to vague and undetermined causes--hæmato-chyluria and elephantoid affections principally. Apart from the interest which attaches to the natural history of the nematoids, they raise, in effect, etiological and prophylactic questions, the extreme importance of which we believe it would be needless to demonstrate. It is greatly to be desired that the researches should be taken up in other parts of the globe, where endemicity and perhaps greater facilities for necroscopic investigation would render them fruitful--Cochin-China, Tahiti, &c. Fresh observations are necessary to confirm the first and to fill up notable gaps. The way has been brilliantly opened by the English and Brazilian physicians. Let our colleagues in the French colonies put their shoulders to the wheel; they have before them a vast field of study to explore.”

Since the above remarks were written I have received several communications from Dr Bancroft, and also others from Drs da Silva Lima, Araujo, Assis Sousa, Paterson, Hall, of Bahia--the two last named being English physicians in practice there. I regret that I can do little more than refer to the writings of these authors in the Bibliography below; but I may observe that Drs Paterson and Hall have ascertained that the proportion of the population of Bahia affected by Filaria is 8-1/2 per cent. Out of 309 persons examined, 26 had hæmatozoa, which is, roughly, one in twelve, or more strictly, 8·666 per cent.

Amongst recent memoirs that by Sir J. Fayrer, read to the Epidemiological Society on the 5th of February, 1879, deserves especial attention. In regard to its significance, I have only space to remark that, much as we may regret the little interest shown by our hospital physicians and surgeons in this subject, it is particularly gratifying to see experienced Indian officers like Sir J. Fayrer, Mr Macnamara, and Dr John Murray, coming forward both to aid and render homage to their junior colleagues in Eastern parts, who are successfully labouring to advance the cause of helminthology and scientific medicine.

In concluding this subject I may observe, that one of the greatest hindrances to the due recognition of the remarkable part played by parasites in the production of human endemics and animal epizoötics arises from the circumstance that no inconsiderable number of minute worms may infest a host without obvious injury. This immunity proves nothing. If, for example, we take the case of _Trichina_ we find that several millions of entozoa may exist in the human, or, at all events, in the animal bearer, without producing any symptom of discomfort. In such cases it is not possible to determine the strict limits of health and disease; nevertheless, were we to double the amount of infection, the imaginary line of demarcation is at once bridged over and the parasites become acknowledged as directly responsible for grave symptoms which may even prove fatal to the bearer. Again, the relative strength and size of the infected host constitute factors that materially limit the power of the parasite for injury. Where the entozoa are of minute size, and where their injurious action is primarily due to the mechanical obstructions they set up, it is clear that the virulence of the helminthiases, or resulting diseased conditions, will mainly depend upon the number of intruders.

Another consideration of the highest value in relation to epidemiology generally, and more especially in regard to the practical question as to the best methods of stamping out parasitic plagues, is that which refers to the life-history of the entozoon itself. It must be obvious that in all cases where the intermediate host can be captured and destroyed, the life-cycle of the parasite can be broken and interrupted, and if thus broken, there is an end to the further propagation of the species. The knowledge that we have acquired by experimental research in this connection has already enabled us to set a limit upon the prevalence of certain well-known disorders, such as Trichinosis, Cestode-tuberculosis, and so forth. In the case of epizoötics, however, which are indirectly due to the action of intermediary hosts that cannot be readily captured or destroyed, then our power of arresting the disease is comparatively limited. In the present case it is probably not necessary either that a dead or living mosquito should be swallowed to insure infection; but it _is_ necessary that the parasitic larvæ should have dwelt within the mosquito in order to arrive at the highest stage of larval growth prior to their re-entrance within the human territory. Undoubtedly, the larvæ are swallowed with potable waters. Perfect filtration before use would certainly check, if in course of time it did not totally extinguish several of the many virulent diseases that now afflict the inhabitants of warm climates.

It is with reluctance that I terminate this article, but in the closing pages of this work (Book II, Section V) I hope to add a few more particulars in reference to Lewis’s latest researches.

BIBLIOGRAPHY (No. 23).--_Araujo, A. J. P. da Silva_, “Memoria sobre a Filariose,” &c., Bahia, 1875; see also ‘Arch. de Méd. Nav.,’ 1875 and 1878.--_Bancroft, J._, “Cases of Filarious Disease,” in ‘Pathological Soc. Trans.’ for 1878, vol. xxix, p. 407.--_Bourel-Roncière_, “_Résumé_ of and Commentary upon the writings of Silva Lima, Silva Araujo, and others,” in ‘Arch. de Méd. Nav.’ for March, 1878.--_Idem_, “Pathologie exotique. De l’hématozoaire nématoïde de l’homme et de son importance pathogénique, d’après les travaux Anglais et Bréziliens des dernières années;” _ibid._, for August and Sept., p. 113-134 and p. 192-214, 1878.--_Cobbold, T. S._, “Discovery of the Adult Representative of Microscopic Filariæ,” ‘Lancet,’ July, 1877, p. 70.--_Idem_, ‘On _Filaria Bancrofti_,’ _ibid._ Oct., 1877, p. 495.--_Idem_, “Verification of Hæmatozoal Discoveries in Australia and Egypt,” ‘Brit. Med. Journ.,’ June, 1876.--_Idem_, “Obs. on Hæmatozoa,” ‘Veterinarian,’ October, 1873.--_Idem_, “Remarks on the Ova of another Urinary Parasite (in the paper on ‘Bilharzia’) from Natal,” ‘Brit. Med. Journ.,’ July 27th, 1872, p. 89; see also Bibl. No. 12.--_Idem_, “Entozoa in Relation to the Public Health” (various papers), ‘Med. Times and Gaz.,’ Jan. and Feb., 1871.--_Idem_, ‘Worms’ (l. c., p. 151), 1872.--_Idem_, “Hæmatozoa; Fresh Discoveries by Lewis,” ‘Lancet’ for Feb. 6, 1875.--_Idem_ (brief notice), the ‘Veterinarian,’ p. 209, March, 1875.--_Idem_, “On the Discovery of the Intermediary Host of _Filaria sanguinis hominis_,” ‘Lancet,’ Jan. 12, 1878, p. 69.--_Idem_, “On the question of Priority of Discovery,” Rep. of Med. Soc. of Lond., in ‘Lancet,’ March 30, 1878, p. 465.--_Idem_, ‘Mosquitoes and Filariæ’ (explanatory note), in ‘Brit. Med. Journ.,’ March 16, 1878, p. 366.--_Idem_, “On the Life-history of _Filaria Bancrofti_, as explained by the discoveries of Wucherer, Lewis, Bancroft, Manson, Sonsino, myself, and others,” “Report of the Proceed. of the Linnean Soc.” for March 7, 1878, in ‘Pop. Science Rev.,’ April, 1878; and afterwards published _in extenso_ in ‘Journal Linn. Soc.,’ Oct. 31, 1878.--_Idem_, “On _Filaria Bancrofti_,” in Part iv of a series of papers on the Parasites of Man, in the ‘Midland Naturalist,’ August, 1878.--_Idem_, “On _Filaria sanguinis hominis_,” in a letter to the ‘Lancet,’ July 13, 1878, p. 64.--_Idem_, “Filariæ and Leprosy” (case from Bancroft); ‘Lancet,’ Feb. 1, 1879.--_Corré, A._, “Note sur l’helminthe rencontré dans les urines hémato-chyleuses,” ‘Rev. des Sci. Nat.,’ 1872.--_Cossé_, “Sur l’helminthe rencontré par Wucherer et Crevaux,” &c., ‘Rev. Montpellier,’ tom. i, p. 190.--_Couto, A._, “These de concourso,” Bahia, 1872.--_Crevaux, J._, “De l’hématurie chyleuse, &c.,” 1872; also in ‘L’Union Médicale,’ 1872 (abs. in ‘Brit. Med. Journ.,’ July, 1872, p. 100); also in ‘Arch. de Méd. Nav.,’ 1874; and in ‘Journ. de l’Anat. et de la Physiol.,’ 1875 (see also Silva Lima).--_Davaine, C._, ‘Traité,’ 2nd edit., p. 944; ‘Hæmatozoaires,’ supp., 1877.--_Fayrer, Sir J._, “Filaria sang. hom.,” ‘Lancet,’ March 16, 1878, p. 376.--_Idem_, “Elephantiasis Arabum,” ‘Med. Times and Gaz.,’ Dec. 1, 1877, p. 588; “On the Relation of _Filaria sanguinis hominis_ to the Endemic Diseases of India,” in the ‘Lancet,’ Feb. 8 and 15, and reprinted from the ‘Med. Times and Gazette’ (same date), 1879.--_Gabb, D. H._, letter in ‘Lancet,’ June 22, 1878.--_Leuckart_, l. c., s. 638, 1876.--_Lewis, T. K._, “On a Hæmatozoon in Human Blood,” ‘San. Comm. 8th Rep.,’ Calcutta, 1872; ‘Med. Press,’ 1873, p. 234; ‘Indian Ann. Med. Sci.,’ 1874; ‘Lond. Med. Rec.’ (abs. by myself in vol. i, p. 5), 1873.--_Idem_, “Pathological Significance of Nematode Hæmatozoa,” ‘Tenth Ann. Rep.,’ 1873, Calcutta (reprint), 1874; ‘Ind. Ann.,’ 1875.--_Idem_, “Remarks regarding the Hæmatozoa found in the Stomach of _Culex mosquito_,” ‘Proc. Asiatic Soc. of Bengal,’ March, 1878, p. 89.--_Idem_, “Flagellated Organisms in the Blood of Rats” (being portion of a paper on “The Microscopic Organisms found in the Blood of Man and Animals,” in ‘14th Annual Report of the San. Comm. with the Govt. of India’), in the ‘Quart. Journ. of Micr. Science,’ Jan., 1879.--_Idem_ (published since the present article was written), “The Nematoid Hæmatozoa of Man,” _ibid._, April, 1879.--_Lima, J. F. da Silva_ (with _Crevaux_), ‘Memoria sobre hematuria chylosa ou gordurosa des paizes quentes;’ extrahida da ‘Gazeta Medica da Bahia,’ 1876; repr. in ‘Arch. de Méd. Nav.,’ Dec., 1878 (see also Le Roy de Méricourt).--_Magalhães, Pedro S. de_, “Filarias em estado Embryonario, encontradas n’agua tida como potavel (agua da Carioca),” ‘O Progresso Medico,’ Dezembro, 1877, p. 57.--_Idem_, “Nota sobre os nematoides encontrados no sedimento deposito pela agua (potavel) da Carioca,” ‘O Prog. Med.,’ 1 de Setemb., 1878, p. 577.--_Idem_, “Caso de filariose de Wucherer;” _ibid._, 15 de Setemb., 1878, p. 589.--_Makina, M.D._, “Filaria in Chyluria,” letter in ‘Lancet,’ Feb. 22, 1879, p. 286.--_Manson, P._, “Rep. on Hæmatozoa,” ‘Customs Gazette,’ No. 33, Jan.-March, 1877; see also ‘Med. Times and Gaz.’ for Nov. 10, p. 513, Nov. 17, p. 538, and Nov. 24, p. 563; Dec. 1, p. 589, 1877; also Jan., 1878.--_Idem_, “Additional Cases;” _ibid._, March 2, 9, 23, 1878.--_Idem_, “On _Filaria sanguinis hominis_, and on the Mosquito considered as a Nurse,” ‘Proc. Linn. Soc.,’ March 7, 1878; see also report in ‘Nature,’ March 28, 1878, p. 439.--_Idem_, “On _Filaria sanguinis hominis_, clinically considered in reference to Elephantiasis, Chyluria, and allied Diseases,” ‘Rep. of Med. Soc. of Lond.,’ in ‘Lancet,’ March 30, 1878.--_Idem_, “Further Observations on _Filaria sanguinis hominis_,” “Med. Rep.” for April-Sept., 1877, in ‘Customs Gazette,’ Shanghae, 1878.--_Idem_, “The Development of the _Filaria sanguinis hominis_,” ‘Med. Times and Gaz.’ for Dec. 28, 1878, p. 731.--_Méricourt, A. Le Roy de_, in Appendix to an art. entitled “Nouvelle phase de la question relative à la nature parasitaire de la chylurie. Découverte du représentant adulte de la ‘Filaire de Wucherer,’” par le Dr da Silva Lima, from the ‘Gaz. Med. da Bahia,’ Sept., 1877; see also the ‘Lancet,’ Jan., 1878, p. 22 (editorial notice).--_Moura, J. de_, ‘These de Concourso,’ 1877.--_O’Neill_, “On Craw-craw,” ‘Lancet,’ Feb., 1875.--_Pareira, A. P._, “On Bilharzia and Chyluria,” ‘Gazeta Med. da Bahia,’ No. 9, 1877 (noticed in ‘Lancet,’ Feb. 2, 1878).--_Salisbury, J. H._, “On the Parasitic forms developed in Parent Epithelial Cells of the Urinary and Genital Organs,” ‘Hay’s American Journ.,’ vol. iv, 1868, p. 376.--_Santos, F. dos_, in ‘Gaz. Med. da Bahia,’ March, 1877.--_Sonsino, P._, ‘Richerche,’ &c., 1874; ‘Della Bilharzia,’ &c., 1876; ‘Sugla Ematozoi,’ &c., 1876 (see Bibl. No. 12).--_Idem_, “On the Diagnosis of Embryos of Filaria,” in his paper ‘Sull’ Anchylostoma duodenale;’ ‘Estr. dall Imparziale,’ 1878.--_Sousa, M. de A._, ‘Memoria sobre a Elephantiasis do escroto,’ Bahia, 1878.--_Wucherer, O._, “Noticia Preliminar,” &c., ‘Gaz. Med. da Bahia,’ Dec., 1868.--_Idem_, ‘Sobre Hematuria no Brazil,’ _ibid._, Sept., 1869; see also “Méricourt’s trans. (De l’hématurie intertropicale observée au Brézil),” ‘Arch. de Méd. Nav.,’ p. 141, 1870, and the fuller references quoted in my memoir; ‘Linn. Soc. Journ., Zool.,’ vol. xiv, p. 368.

_Filaria Loa_, Guyot.--Although further examinations of this worm will probably result in placing it in some other genus than _Filaria_, yet it is by no means clear that Diesing was right in placing it with the genus _Dracunculus_. I therefore abandon the nomenclature adopted in my previous treatise. According to the surgeon, Guyot, who made seven separate voyages to the coast of Angola, these worms cannot be confounded with the Dracunculus. They are quite white, and relatively much thicker than guinea-worms. Under the title of _Filaria oculi_ Moquin-Tandon has spoken of certain small nematodes as “not uncommon in the negroes of the Angola coast;” and he gives other localities where it occurs. The worms are identical with those described by Guyot as dwelling beneath the conjunctivæ of negroes at Congo and in the Gaboon region generally. The parasite is rather more than an inch and a quarter in length, being pointed at one end and blunt at the other. It is termed _Loa_ by the natives, who state that after a period of several years the worm voluntarily quits the organ. The disease is thus naturally cured. This parasite enjoys a tolerably wide geographical distribution, as it has been observed by Clot Bey in a negress who had come from the town of Monpox, situated on the banks of the River Magdalena; by Sigaud, who saw one in the eye of a negress in Brazil; by Blot, at Martinique, who saw two in a negress originally from Guinea; by Bajon, who met with one in a little negro girl who had come from Guadeloupe; by Mongin, who found one in a negress who had been living in the Island of San Domingo; and by Lestrille, who removed one from beneath the conjunctiva of a negro who came from Gaboon.

BIBLIOGRAPHY (No. 24). _Davaine_, l. c., p. 839.--_Guyon_, ‘Gaz. Méd. de Paris,’ p. 106, 1841, and in ‘Micr. Journ. and Struct. Record,’ p. 40, 1842, and in ‘Dublin Journ.,’ vol. xxv, p. 455, 1839.--_Idem_, ‘Compt. Rendus,’ tom. lix, p. 743, 1865.--_Guyot_, in ‘Mém. par Arrachait,’ p. 228, 1805.--_Küchenmeister_, l. c., s. 322.--_Lestrille_, in Gervais and Van Beneden’s ‘Zool. Med.,’ 1859, also quoted by Davaine, l. c., 2nd edit., p. 840.--_Leuckart_, l. c., s. 619.--_Moquin-Tandon, A._, ‘Zool. Med.,’ Hulme’s edit., p. 363, 1861.

_Filaria lentis_, Diesing.--This is a doubtful species. The worm was first discovered by Nordmann, in a case of lenticular cataract under the care of Von Gräfe, and it was afterwards found by Jüngken in a similar case, as recorded by Sichel. There is also the instance described by Gescheidt, in which Von Ammon operated, and from which brief descriptions of the worm have generally been taken. In this case there were three worms, two measuring about 1/6″ and the third 1/15″ in length. In Jüngken’s case (exhibited by Quadri, of Naples, at Brussels) the worm was more than 3/4″ long. In another case, reported by M. Fano, the worm was somewhat less than 1/4″ long. There is no certain evidence that any of these various worms had developed sexual organs in their interior. It is true that the reproductive organs were described in two of the worms observed by Gescheidt; but after a due consideration of all the facts I fear we must conclude that all the worms in question were sexually-immature and wandering nematodes, possibly referable to Gurlt’s _Filaria lacrymalis_, as Küchenmeister long ago suggested.

BIBLIOGRAPHY (No. 25).--_Cobbold_, ‘Entozoa,’ p. 332.--_Davaine_, l. c., p. 821 _et seq._--_Diesing_, ‘Syst. Helm.,’ p. 625.--_Fano_, ‘Traité des Malad. des Yeux,’ tom. ii, p. 498; and in ‘Rec. de Méd. Vét.,’ p. 140, 1869; quoted by Davaine, p. 831.--_Gescheidt_, Ammon’s ‘Zeitsch.,’ 1833, s. 435.--_Leuckart_, l. c., Bd. ii, s. 622.--_Nordmann_, l. c., Bibl. No. 2, s. 7, 1832.--_Sichel_, ‘Iconogr. Ophth.,’ p. 707, 1859.

_Filaria labialis_, Pane.--This is a filiform cylindrical worm measuring an inch and a quarter in length. The mouth is armed with four papillæ arranged in the form of a cross. The tail of the female is blunt, the vaginal outlet being placed at a very short distance from its extremity, and a little above or in front of the anus. This parasite was found by a medical student at Naples. It occupied the cavity of a pustule in the upper lip, giving rise to considerable irritation. Only the male worm is at present known.

BIBLIOGRAPHY (No. 26).--_Davaine_, l. c., edit. ii, Synopsis, p. 107.--_Leuckart_, l. c. (with a fig.), Bd. ii, s. 616.--_Pane_, “Nota di un elminte nematoide,” in ‘Annali dell’ Acad. degli aspiranti Naturalisti,’ Napoli, ser. 3, vol. iv, 1864.

_Filaria hominis oris_, Leidy.--In the fifth volume of the ‘Proceedings of the Philadelphia Academy of Natural Sciences’ (1850, p. 117) Dr Leidy furnishes the following description of this worm as gathered from the examination of a simple specimen preserved in alcohol, and labelled as having been “obtained from the mouth of a child.” Body white, opaque, thread-like; mouth round, simple; posterior extremity obtuse, furnished with a short, curved, epidermal hooklet, 1/500″ in length, by 1/2000″ in diameter at base. Dr Leidy offers some speculations as to its origin, but from whatever source the worm was obtained by the bearer, it seems to be an immature form. Its length is five inches and seven lines.

_Filaria_ (_Nematoideum_) _trachealis_, Bristowe and Rainey.--This is another very doubtful worm. It was originally described in the ‘Pathological Society’s Transactions’ for 1855. It evidently represents only a juvenile stage of growth of some species of round worm. Rainey discovered a considerable number of these worms in the trachea and larynx of a person who died from a disease affecting the lower extremities. Individually the parasites measured about the 1/50″ in length.

_Strongylus_ (_Filaria_) _bronchialis_, Rudolphi.--This is a small nematode. The male measures rather more than half an inch, whilst the female is upwards of an inch in length. The caudal appendage of the male is furnished with a bilobed, membranous, half-bell-shaped bursa. This surrounds the cloacal outlet, the latter concealing a double spiculum. The tail of the female is sharply pointed, the anal orifice being placed a little in front or above. The body is filiform, of a pale yellow color. It is about 1/50″ broad in the male, and 1/35″ in the female. The mode of reproduction is viviparous.

The original specimens were discovered by Treutler in Germany, during the winter of 1791, in the bronchial glands of an emaciated subject, whilst those sent to Diesing for description were discovered by Dr Fortsitz at Klausenberg, in Transylvania, in the lungs of a boy six years old. Diesing and Weinland suggested the identity of _Filaria bronchialis_ and _Strongylus longevaginatus_, whilst Küchenmeister went further, and pronounced them to be one and the same species.

BIBLIOGRAPHY (No. 27).--_Cobbold_, ‘Entoz.,’ p. 357.--_Davaine_, ‘Synops.,’ l. c., ‘Synopsis’ cix.--_Küchenmeister_, l. c., Eng. edit., p. 381.--_Leuckart_, l. c., s. 618.--_Treutler, F. A._, “De vermibus filiformibus (_Hamularia lymphatica_) in glandulis conglobatis bronchiorum repertis,” in ‘Obs. Pathol. Anat.,’ 1793.--_Wedl._, ‘Die im Menschen vorkommenden Helminthen’ (quoted by Leuckart), Wien, 1862, s. 22.

_Eustrongylus gigas_, Diesing.--This is by far the largest nematode known to science, the male sometimes measuring a foot in length and the female more than three feet, whilst the breadth of the body reaches half an inch at the thickest part. Though fortunately very rare in man, this worm is known to occur in a great variety of animals, especially in weasels. According to Weinland and Jackson, it is particularly abundant in the kidney of the North American mink (_Mustela vison_), destroying the substance of the organ, the walls of which become the seat of calcareous deposit. It has been found in the dog, wolf, puma, glutton, raccoon, coati, otter, seal, ox, and horse.

The body of the adult worm is cylindrical, more or less red in color, and somewhat thicker behind than in front. The head is broadly obtuse, the mouth being supplied with six small, wart-like papillæ, two of which correspond with the commencement of the two lateral lines of the body. These lines are also distinguishable from other six longitudinal lines traversing the body from end to end by the presence of very minute papillæ which are less closely arranged towards the centre (Leuckart). The tail of the male shows a simple, thick, cup-shaped bursa, which is destitute of rays, and partly conceals the simple spiculum. The tail of the female is blunt and pierced by the centrally placed anal opening. The vulva is situated near the head in the ventral line. The eggs are stout and oval, measuring 1/300″ in length by about 1/550″ in breadth.

As regards development the recent researches of Schneider have shown that certain kinds of fish play the part of intermediary bearer. Balbiani preserved the ova in water for more than a year without their hatching, and all his attempts to rear the larvæ in the intestines of the dog by direct experiment failed. Similar feeding experiments upon fishes and reptiles also failed. The embryo, when removed from the egg, measures 1/104″ in length. It is vermiform, having a pointed head and simple mouth. Balbiani describes the buccal cavity as containing a protractile stylet. Notwithstanding the negative results obtained by Balbiani’s experiments on fishes, Schneider (from anatomical data, which Leuckart confirms) has placed it almost beyond question that the worm hitherto known as _Filaria cystica_ is the sexually-immature _Eustrongylus gigas_. This worm is found encysted beneath the peritoneal membrane in _Galaxias scriba_ and _Synbranchus laticaudatus_. It is worthy of remark that the genus Galaxias comes nearer to the Salmonidæ than to the pike family, whilst the Synbranchi are tropical oceanic fishes. Probably the sexually-immature worm occurs in other fishes, especially the Salmonidæ.

Remarkably fine examples of the adult worm may be seen in the Hunterian Collection, Lincoln’s Inn, and in the Museum of the Royal Veterinary College. The human example is undoubtedly genuine. The dissections in the Hunterian Collection of specimens were made by me in 1865. Objection has been taken to my description of the œsophagus as “spiral.” In Sheldon’s specimen it is certainly twisted upon itself, precisely in the manner in which Davaine has also figured it (‘Traité,’ fig. 68); but I cannot here give further anatomical particulars. Drelincourt found two worms sexually united in the kidney. When once the parasites have gained access to this organ, rapid destruction of the glandular substance follows. Ultimately the kidney is reduced to the condition of a mere cyst or bag, which, besides the worms, contains a quantity of sanguineo-purulent matter. Frequently only one worm is present, but oftener two or three. In the kidney of a puma D’Azara’s friend, Noseda, found no less than six worms, whilst Klein obtained eight from the kidney of a wolf.

BIBLIOGRAPHY (No. 28).--_Azara, F. de_, ‘The Natural History of the Quadrupeds of Paraguay,’ trans. from the Spanish by W. P. Hunter; Valpy’s edit., p. 43, 1837; Black’s, 1838; French edit., p. 313, 1801.--_Albers_, ‘Beitr. z. Anat. &c.,’ Bd. i, s. 115.--_Aubinais_, ‘Revue Méd.,’ 1846, p. 284.--_Balbiani_, “Recherches,” &c., ‘Compt. Rend.,’ 1869, p. 1091; ‘Rec. de Méd Vét.,’ 1870, p. 5.--_Bickford_, “Spec. of _Str. gigas_ found in the Kidney of a Dog,” the ‘Veterinarian,’ 1859, p. 312.--_Blainville_, ‘Dict. des Sci. Nat.,’ tab. 29.--_Blanchard_, ‘Ann. des Sci. Nat.,’ 1849, p. 186.--_Idem_, in ‘Cuvier’s Règne Animal’ (Masson’s edit.), ‘Les Intestinaux,’ p. 57, pl. 27.--_Blasius_, ‘Obs., &c.’ (with fig. of Lumbricus in renibus hominis), 1674, p. 125.--_Bobe-Moreau_, in ‘Journ. de Méd.,’ tom. xlvii.--_Boerhaave_, ‘Aphorism.,’ 1728.--_Bremser_ (l. c., Bibl. 2), s. 223.--_Chabert_, ‘Traité des maladies verm. dans les Animaux,’ 1782.--_Chiaje_, ‘Comp. d. Elmintogr. umana,’ p. 106.--_Clamorgan, J. de_, ‘La Chasse de Loup,’ 1583 (quoted by Davaine, the worms being described as “serpents et bêtes fort venemeuses”).--_Cobbold_, ‘Entoz.,’ p. 358.--_Idem_, ‘Catalogue of Entozoa in the Museum of the Roy. Coll. of Surg.,’ “Descr. of preps. Nos. 19-25,” p. 3, 1866.--_Idem_, “Parasites of Man,” ‘Midland Naturalist,’ Dec., 1878.--_Collet-Meygret_, “Mém. sur un ver trouvé dans le rein d’un Chien,” in ‘Journ. de Physique,’ &c., 1802.--_Cuvier_, see _Blanchard_ (supra).--_Idem_, ‘Voyage en Sicile,’ and in ‘Ann. des Sci. Nat.,’ tom. xi.--_Davaine, C._, ‘Traité,’ l. c., deuxième edit., p. 271 _et seq._ (with full lit. refs. at p. 290).--_Diesing_, l. c., vol. ii, p. 325.--_Dujardin_, l. c., p. 113.--_Frank, F._, “Ein Spulwürm in der Urinblase eines Hundes,” ‘Hufeland’s Journ.,’ Bd. xviii, s. 112.--_Jackson_, ‘Catalogue of the Boston Museum,’ 1847, p. 317.--_Klein, T. K._, “Anatomical Description of Worms found in the Kidneys of Wolves,” ‘Phil. Trans.,’ 1729-30, p. 269.--_Küchenmeister_, l. c., Eng. edit., p. 376.--_Leblanc_ (rep. by Rayer and Bouley), in ‘Bull. de l’Acad. de Méd.,’ 1850, p. 640; in ‘Rec. de Méd. Vét.,’ 1862, p. 800; and quoted by Davaine.--_Leuckart_, l. c., Bd. ii, s. 353-401, 1876.--_Moublet_, “Mém. sur les vers sortis des reins et de l’urethre d’un enfant,” ‘Journ. de Méd-Chir. et Pharm.,’ 1758, pp. 244 and 337.--_Otto_ (Anat.), in ‘Mag. d. Gesellsch. naturf.,’ 1814.--_Owen_, art. “Entozoa,” in Todd’s ‘Cyclop.’--_Rayer_, ‘Traité des maladies des reins,’ 1841.--_Rayger_, ‘Sur un serpent qui sortit du corps d’un homme après sa mort’ (quoted by Davaine, l. c., p. 272), 1675.--_Schneider_, ‘Monographie der Nematoden,’ 1866, s. 50.--_Idem_ (mit Peters), quoted by Leuckart, l. c., s. 382.--_Stratton_, in ‘Edin. Med. and Surg. Journ.,’ p. 261, 1843.

_Dochmius duodenalis_, Leuckart.--Much time might be occupied and wasted over the nomenclature of this parasite. In my previous treatise, and for reasons there stated, I placed it under the genus _Sclerostoma_. On rather slender grounds Dubini formed the genus _Anchylostoma_ for its reception, but Von Siebold thought that, on account of the absence of symmetry in the arrangement of the so-called dental organs, Dubini’s genus might very well be allowed to remain. Bilharz, Diesing, Küchenmeister, Wucherer, and others have retained the genus as either _Anchylostoma_ or _Anchylostomum_. Schneider keeps it amongst the _Strongyli_; but after all that has been said and written there can, I think, be no doubt that if Dujardin’s genus _Dochmius_ is to be retained at all, Dubini’s worm must be placed in it. The comparisons instituted by Leuckart afford sufficient proof of the intimate alliance as between _Anchylostoma_ and _Dochmius_. Professor Molin thought to meet the difficulty by calling the worm _Dochmius anchylostomum_, but the specific term, _duodenale_, should certainly be retained.

This worm was discovered by Dubini at Milan, and though at first thought rare, it is now known to be tolerably common throughout Northern Italy. The worm has also been recently found by Dr Kundrata at Vienna, in an Austrian subject. According to Pruner, Bilharz, and Griesinger, it is abundant in Egypt. Griesinger believed that about one fourth of the people of that country suffered from anæmic chlorosis, solely in consequence of the presence of this worm in the small intestines. From Wucherer’s observations especially, we know that Dubini’s worm is not limited to the localities above mentioned, for it occurs in the western tropics, in Brazil, and even in the Comoro Islands.

The worm may be described as a small nematode, the males measuring 3/8″ or rather more, whilst the females extend to very nearly 1/2″ (12 mm.). The head is pointed and tapering, and bent forward, having the mouth directed towards the ventral aspect. The oral opening is armed with four asymmetrically disposed, unequally-sized, horny, conical, converging teeth. The neck is continuous with the cylindrical body, which is 1/80″ in thickness. The body terminates in a straight cone-shaped, or rather sharply-pointed tail in the female, the caudal extremity of the male ending in a partially inflexed, blunt point. In the male there is a cup-shaped, bilobed bursa, the membranes of which are supported by eleven chitinous rays, ten being simple, whilst the median, or odd one, is bifurcated at the summit. The mode of reproduction is viviparous. Adult males and females occur in the proportion of one of the former to three of the latter.

As above mentioned, it was Griesinger who first pointed out the clinical importance of this entozoon. He first explained the manner in which the worm produces anæmia, the persons attacked losing blood as if they were being bitten by innumerable small leeches. Like the rest of their kindred, these worms are veritable blood-suckers. In the first instance the views of Griesinger met with opposition, but they have since received abundant confirmation. Whilst Küchenmeister’s ‘Manual’ furnishes an excellent account of the disorder as known in Europe, we are chiefly indebted to Wucherer for what is known of the disorder in Brazil. The experiences recorded in the ‘Deutsches Archiv für Klinische Medicin’ for Sept. 27th, 1872 (s. 379-400), were amongst the last that appeared from the pen of that gifted and amiable physician. As little or no notice of his writings appears to have been taken by professional men in this country, I depart somewhat from the design of this work when I venture to abstract a few of the clinical particulars which he has supplied. Their importance in relation to sanitary science is obvious, inasmuch as these parasites are introduced into the human body by drinking impure water, or, at least, water which either contains the free larvæ of the worm, or the intermediary bearers that harbor the larvæ.

It should be borne in mind that Dubini’s original discovery was made at Milan in 1838, whilst Griesinger’s recognition of the worm as a cause of the Egyptian chlorosis resulted from a post-mortem examination made on the 17th of April, 1851.

In the journal above mentioned, Wucherer records his own discoveries as follows (‘Ueber die Anchylostomunkrankheit,’ &c.):--“Although Griesinger with well-founded confidence gave an account of his ‘find’ and its significance, yet it remained for a long time unnoticed and unutilised, till at length a case led me to corroborate it. During my many years’ residence in Brazil, especially during the first year, I had very frequent opportunities for witnessing the tropical chlorosis, but seldom to treat it, as it is one of those diseases for which Brazilians seek no medical assistance. Its treatment falls to the lot of the _curiosos_, _curadeiros_ (quacks), who employ the fresh pulp of a species of fig as a remedial agent with the best results. On the 13th of December, 1865, I was called to the Benedictine monastery in Bahia to see a slave of the _order_ suffering from _hypoæmia_. The patient was about thirty years of age, married, a strongly built mulatto. He was a field laborer on the Ingua plantation of the order, who exhibited in a conspicuous degree all the symptoms that occur in hypoæmia except the diarrhœa. He was well nourished, but strikingly pale, his whole face, but especially the eyelids, being œdematously swollen, as also were the feet, legs, and hands. The hands and feet were very cold. His appearance betrayed the most horrible anguish or low despondency. With difficulty only could he raise himself, being obliged to lie down again immediately on account of his weakness. Auscultation revealed a diminished respiratory murmur, and bronchial expiration in both lungs. The pulse was very rapid and small, the patient complaining of pain in the region of the heart. He had frequent palpitation when he moved, and he complained of pain in other parts of the body. His abdomen was much distended by gases, but not sensitive to pressure from without, except in the region of the stomach. The urine was clear, its specific gravity 1007 to 1023-1/2°. Under great difficulties he resided for several months after his marriage at Inhatâ. Earlier he had been on the estates of the order at Rio de S. Francisco. He there suffered for a long time from intermittent fever, but at Inhatâ he entirely recovered. At Inhatâ the slaves frequently suffered from hypoæmia, but in S. Francisco not at all. He appears not to have made any misuse of brandy. The slaves of the order were well cared for, and supplied with good and wholesome nourishing food. The patient had already, for a long period, treated himself with steel wine, yet was continually getting worse and worse. He had not taken the pulp of the fig. As I was unaware he had suddenly become so ill, they hastily despatched a message to the town. There was no good to be expected from the further employment of iron, and the patient was in such a condition that from the very first I despaired of his recovery. I immediately prescribed the pulp of the Gammeleira (_Ficus doliaria_), but it could not be easily obtained. Considering that the Gammeleira would have a drastic effect, I therefore prescribed two grammes of elaterium, to be divided into eight doses, of which he should take one every three hours.” Dissatisfied with this advice, however, Dr Wucherer goes on to say that on reaching home he carefully looked up the literature of the subject. “In a ‘Geologico-Medical Report’ by Professor Hirch, recorded in the ninety-sixth volume of ‘Schmidt’s Jahrbucher,’ I found how Griesinger had recognised the _Anchylostoma_ as the cause of the Egyptian chlorosis, which was clearly identical with our _hypoæmia_. He had employed this commended anthelmintic. I resolved the more to prescribe the pulp of the Gammeleira when I found it described as a worm-expelling remedy in Martin’s ‘Systema Materiæ Vegetabilis Braziliensis.’ The next morning, however, when I arrived at the monastery I learnt that my patient died about two hours after a slight evacuation. Only after much resistance would they permit the _sectio cadaveris_. I merely opened the abdomen, and was surprised to find everything as Griesinger had described. During the next season, through the courtesy of my colleagues attached to the General Infirmary at Bahia, especially of Drs Silva Lima, Faria, and Caldos, I was enabled to open more than twenty bodies of anæmically deceased individuals. All were selected as miserably poor in condition, but only five were bodies of persons in whom hypoæmia was diagnosed, and in these there were a great number of Anchylostomes in the small intestine. The intestines of the other bodies contained either none, one, or a few.” Dr Wucherer next states that he compared the characters presented by his entozoa with those given by Dubini, Diesing, and Von Siebold, and found a perfect agreement throughout. He sent several examples to Griesinger, who also established their identity, and communicated the results of his investigations accordingly (‘Archiv für Heilkunde,’ 1866, s. 387. See also Leuckart, ‘Die Mensch. Par.,’ Bd ii, s. 411). Dr Wucherer also forwarded a number of specimens to Dr Weber, who published a brief account of them with excellent figures (‘Path. Soc. Trans.,’ vol. xviii, 1867, p. 274). As mentioned in the text of his memoir (s. 394), Dr Wucherer also transmitted some strongyloids to myself. “The publication of my observations,” adds Dr Wucherer (‘Gazeta Medica da Bahia,’ 1866, p. 27 _et seq._), “had a result in that Dr J. R. de Moura, of Thersepolis, in the province of Rio de Janeiro, sought for Anchylostomes in the bodies of tropical anæmics (_Hypöæmikern_). He at once found these parasites, as stated in the same journal (for 1866, p. 132). As occurred to myself, he saw no enduring results from the application of the remedies which appeared to be called for, whilst he well knew that unprofessional persons (Nichtärzte) succeeded in obtaining marked results by the exhibition of the pulp of the Gammeleira (_Ficus doliaria_). The anthelmintic action of this remedy was also unknown to him.” Dr Wucherer then records how his discovery of these entozoa was announced by Dr Jobini to the Rio academy, and how Dr Moura’s observations were subsequently communicated, adding remarks upon the interesting discussion that followed. The general opinion was that the _Anchylostomata_ were _not_ the primary and necessary cause of this tropical anæmia, but rather a co-operating agent in its production. Against this view Dr Wucherer afterwards very properly protested (‘Gazeta,’ Jan. 15th, 1868). In the mean time, says our author, “Dr le Roy de Méricourt, prompted by my first communication, had invited the physicians of the French colony to seek for Anchylostomes. Drs Monestier and Grenet, at Mayotta (one of the Comoro Isles, which lies about 12° S. lat. to the north-east of Madagascar), ascertained the presence of entozoa in hypoæmics. Dr Grenet sent the duodenum and a portion of the jejunum of an hypoæmic corpse to Le Roy de Méricourt, who compared the Anchylostomes with Davaine’s description, and recognised them as examples of _A. duodenale_.”

“In the year 1868 Dr Rion Kérangel found Anchylostomes in the bodies of hypoæmics in Cayenne. Thus, the occurrence of Anchylostomes in hypoæmics has been authenticated by Pruner, Bilharz, and Griesinger, in Egypt; by myself, Dr Moura, Dr Tourinho, and other physicians, in Brazil; by Monestier and Grenet, in the Comoros; and by Rion Kérangel in Cayenne. It thus also appears, from the wide separation of these several localities, that the Anchylostomes, if duly sought for, will be found in many other countries.”

These details given by Wucherer are so precise and instructive that I could not have further abridged them without injustice to his record. The bearing of the foregoing facts in relation to the question as to how we may hope to arrest the fatal action of many of these nematodes is sufficiently obvious. That strongyles and their allies prove highly destructive to man and beast is as well established as any other recognised conclusion in medical science; nevertheless, there are those who still doubt the power of these nematodes in relation to the production of fatal epidemics. I shall deal with the sanitary bearings of the subject hereafter. In conclusion, I may mention that Dr da Silva Lima has forwarded specimens of _Anchylostomum_ to the Hunterian Museum, where they may be seen.

BIBLIOGRAPHY (No. 29).--_Bilharz_, ‘Zeitschr. f. wiss. Zool.,’ Bd. iv, s. 55.--_Cobbold_, ‘Entozoa,’ p. 361.--_Idem_ “Remarks on Recent Contributions to our Knowledge of the Parasitic Nematoids, especially in reference to the Wasting Diseases they produce in Man and Animals,” the ‘Veterinarian,’ Jan., 1876, p. 1.--_Davaine_, l. c., pp. 118 and 931.--_Diesing_ “Revis. der Nematoden,” ‘Sitzb. d. m.-naturw. cl. d. k. Akad.,’ 1860, s. 716.--_Dubini_, ‘Entozoografia,’ &c., 1849.--_Griesinger_ (quoted above), see also ‘Arch. f. Phys. Heilk.,’ 1854.--_Küchenmeister_, l. c., Eng. edit., p. 383.--_Leuckart_, l. c., ss. 410-455.--_Molin_, ‘Il sottordine degli Acroffali,’ p. 61 (quoted by Leuckart).--_Siebold_, ‘Zeitsch. f. wiss. Zool.,’ 1852, s. 55.--_Sonsino, P._, _L’Anchilostoma duodenale_ in ‘relazione coll’ Anemia progressiva perniciosa,’ Egitto, 1877.--_Idem_, ‘Sull.’ _Anch. duod._, 1878 (see also Bibliog. No. 27, both reprinted from ‘Imparziale.’)--_Weber, H._, l. c., 1867.--_Wucherer_ (quoted above), 1872.

_Dracunculus medinensis_, Cobbold.--This parasite is popularly known as the guinea-worm, or Medina-worm. Probably Lister was the first writer who distinctly spoke of it as the Dracunculus, 1690, the same title being applied to it by Kaempfer, 1694. Be that as it may, Gmelin, long afterwards, placed the parasite in the genus _Filaria_, at the same time adopting the specific title _medinensis_. This had been previously employed by Linneus, who, however, regarded the worm as belonging to the genus _Gordius_. It being clear from the distinctive characters of the entozoon that it was desirable to separate it from the Filariæ, and that no better generic name could be devised than _Dracunculus_, I thought it right to combine Lister’s and Gmelin’s nomenclature as above, 1864. Leuckart pursued a similar course, crediting Linneus with the titles.

The guinea-worm having been known from the earliest times, it is not surprising that its true nature long remained a mystery. Any one who has read Küchenmeister’s elaborate narrative of the historical significance of the Dracunculus will hardly have failed to arrive at the conclusion that Moses was probably the earliest writer on the endemic disorder which is occasioned by this parasite. There can be no doubt that the “fiery serpents” which afflicted the children of Israel during their stay in the neighbourhood of the Red Sea were neither more nor less than examples of our Dracunculus. It is further evident that Plutarch spoke of Dracunculi, when in the eighth book of his ‘Symposiacon,’ he quotes Agatharchidas as stating that the people taken ill on the Red Sea suffered from many strange and unheard-of attacks, amongst other worms, from “little snakes, which came out upon them, gnawed away their legs and arms, and when touched retracted, coiled themselves up in the muscles, and there gave rise to the most insupportable pains.” In order to render the passage more readable, it will be seen that I have slightly altered the original version (‘Parasites,’ s. 305).

The guinea-worm may be described as a nematode measuring from one to six feet in length, having a thickness of 1/10th of an inch. The body is uniformly cylindrical, terminating below in a more or less curved and mucronately pointed tail. The head is flatly convex or truncate, having a central, simple mouth, which is surrounded by four equi-distantly and cruciately disposed papillæ. The mode of reproduction is viviparous, the body enclosing a prodigious number of hatched embryos, which, by distension of the uterine ducts, almost entirely obliterate the somatic cavity. Notwithstanding the statements of Owen to the contrary, the male Dracunculus is at present altogether unknown.

The guinea-worm possesses a comparatively limited geographical range, for not only is it proper to the tropical regions, but within intertropical limits it is almost exclusively confined to certain districts in Asia and Africa. Thus, according to Künsenmuller, as quoted by Busk, it occurs endemically in Arabia Petræa, on the borders of the Persian Gulf and Caspian Sea, on the banks of the Ganges, in Upper Egypt, Abyssinia, and the coast of Guinea. “In America the guinea-worm is unknown, except in persons who have had communication with Africa or other parts where it is indigenous. The island of Curaçoa is the only locality in the New World which offers an apparent exception to this fact, and it would be highly desirable to ascertain the real state of the case in this instance.” The observations of Chisholm showed that the Dracunculus is really prevalent in several of the West Indian islands, especially in Grenada, and the still later investigations of Dr Da Silva Lima point to its former prevalence in Brazil. Now, the worm is rarely seen at Bahia. Mr Busk said:--“Though endemic only in the above-mentioned parts of the world, it would yet appear that all races of mankind are obnoxious to the attacks of the _Filaria_ when exposed to what may be called the contagion; that is, when placed in circumstances under which it might be supposed a contagious _seminium_ could be conveyed to them.” Mr Busk also added:--“I have known many instances tending to prove that, in order that a European should become infected with the guinea-worm on the coast of Africa, it is not necessary that he should have been on shore at all. It has been quite sufficient for him to have exposed the bare surface of some parts of his person to the water in the native canoes alongside, or, it may be, to the discharge from the sores of those laboring under the disease. This mode of its introduction accounts for the frequency with which the legs and feet are attacked by the parasite, in preference to other parts of the body, as it will always, I believe, be found that the men who have become so affected have been in the habit of going about with bare feet, as is common among sailors in warm latitudes. That the contagious material is conveyed in water is also further indicated by the well-known fact that in India, where it is the custom of the natives to carry water in skins on their backs, the worm makes its appearance on the back and shoulders and upper part of the body.” These views were published by Busk in 1846, and I am free to confess that--confirmed as they appeared to be by subsequent and independent testimony--they completely dominated my conceptions as to the mode of ingress of the young parasites within the human bearer. Thus, those of our Indian troops which were most exposed during the rainy season, subsequently exhibited evidence of having been invaded by the Dracunculus. As, moreover, the period of incubation of the entozoon commonly extends from twelve to fifteen months, it necessarily happened that the disease often showed itself in localities far distant from the spot where the troops originally contracted the disorder. The statement that the period of incubation of the worm is not less than a year, is probably incorrect, since Carter mentions that in a school of fifty boys bathing in a certain pond at Bombay--the sediment of which swarmed with microscopic tank-worms (_Urobales palustris_, Carter)--twenty-one were attacked with Dracunculus during the year, whilst the boys of other schools, bathing elsewhere, remained, with few exceptions, uninfected. This is a remarkable occurrence, and it points to the possibility of the young Dracunculi being confined to particular pools. That they should, whether occupying the bodies of intermediary bearers or not, be more abundant in some waters than others, is just what might be expected, since such a distribution is in harmony with a recognised law affecting the abundance or limitation of species in particular localities. Much, indeed, has been written respecting the nature of the soil and geological formations occurring in the Indian worm-districts, but the speculative views enunciated on this point are little worthy of credit. Those who desire information on this head should at all events consult the valuable writings of Smyttan, Greenhow, Bird, Forbes, Chisholm, and Aitken, who, apart from the question at issue, supply abundance of practical information.

Into the anatomy of the adult Dracunculus I do not enter, but I may remark in passing, that the structure of the worm has been exhaustively treated of by Busk and Bastian. A _résumé_ of their views is given in my introductory treatise. Carter and Leuckart have also added important details. As regards the structure and development of the young worms, I have to observe that the discovery of the viviparous mode of reproduction in Dracunculus is due to Jacobson. Nearly a quarter of a century ago I recognised the fact that the uterine organs of the adult worm almost completely filled up the perivisceral cavity, and that they were crowded with microscopic worms. Referring to this “find,” the late Sir George Ballingall, of Edinburgh, in his well-known work on ‘Military Surgery,’ recorded the circumstance in the following terms:--“The Assistant Conservator of the Anatomical Museum in our University has detected _in the oviduct_ of an adult specimen from my collection myriads of minute and perfectly-developed (embryonic) Dracunculi. They can be very well seen with an half-inch object-glass, but their structure is best exhibited if the magnifying power be increased to two hundred and fifty diameters linear.” As already stated in my introductory treatise, these observations were made during the winter of 1853-54. In July, 1854, M. Robin made a similar statement after examining a fresh _Dracunculus_ which had been extracted from the leg of a man by M. Malgaigne. Robin, not unsuitably, compared the worm to a double tube, one tubular sheath, as it were, enclosing the other. “The second tube,” he distinctly affirms, “_is the oviduct, or, rather, that part which represents the uterus_. The young still remaining in the uterus were nearly all coiled, sometimes with the tail sallying outwards, at others rolled like the rest of the body.” I have thought it only due to Robin and myself to show that from the first we were perfectly well acquainted with the fact of the “great development of the genital tube and of its close adherence to the parietes of the body.” To be sure, many discrepancies occurred in our writings, and in those of Busk and Carter. It was Bastian’s skill and good fortune to correct these errors. Thus, most of us agreed in recognising a slightly trilobed or tripapillated mouth; but Carter failed to demonstrate the existence of these tubercles, and spoke of the oral aperture as being simple and “punctiform.” The body throughout its three upper fourths appeared to me to be cylindrical, but Robin found that it was flattened. It is finely striated transversely, except at the part where it contracts to form the slender, pointed tail. According to Carter, Robin, and Davaine, the young attain a length of about 1/33 of an inch, but Bastian gives it as about 1/42″. In thickness, Carter gives the approximative diameter as 1/633″, Robin makes it 1/990″ to 1/1320″, whilst Bastian gives their breadth at 1/1428″, and Davaine at 1/2500″. I estimated their greatest length and breadth to be 1/30″ by 1/1000″. Robin and myself thought we recognised a distinct, rounded, anal orifice; and whilst Busk, on the one hand, saw nothing which in the slightest degree indicated the presence of an anal opening, Carter, on the other hand, described the structure which we called the anus as a gland, at the same time placing the alimentary outlet on one side and a little above it. According to Bastian, “the intestinal tube is about 1/87″ in length, and appears to consist of a simple canal of varying calibre, pursuing a nearly straight course, and terminating exactly at about the middle, in length, of the worm.” Like Robin, Bastian recognised œsophageal and stomachal divisions, and in a few examples he observed the cæcal or terminal portion of the intestine to be partially reflected upon itself. In regard to the circular opening which Robin and myself described as the anus, Bastian says there is a rounded body, “about 1/2200″ in diameter, with a dark or light spot in the centre, according to the varying focal distance, and which seems to represent a central aperture. Sometimes, above this, traces of two or three large cells may be recognised, whilst behind nothing definite can be made out, save that the cavity of the body is visible for about 1/400″. In other specimens of the young worm the central body and spot are wanting, but, in its stead, two lateral sacculi are met with, about 1/3300″ in diameter, that communicate with the exterior by a minute channel through the integuments, which can sometimes be distinctly recognised. At other times the channel is obscured by protrusion, which appears to have taken place through it, of a minute bilobed papilla, projecting 1/10,000″ from the side of the body. When the projections are seen, the sacculi are indistinct.”

As Bastian found the young in all stages of development from the germ condition 1/5000″ in diameter up to the perfect embryo, and as, moreover, he, like the rest of us, could detect no sexual orifice in the adult Dracunculus, he was led to express his belief that the young were produced agamogenetically. He went so far as to call the germs _pseudova_. It was with great reluctance that I dissented from the views of so gifted an observer as Bastian; nevertheless, later researches have shown that I was justified in not hastily concurring in the theory of a non-sexual mode of reproduction for Dracunculus.

Among the many advances of modern helminthology, the discovery of the true source of the guinea-worm is not the least important. To the late M. Fedschenko (the lamented and accomplished Russian traveller, who lost his life in a snowstorm on the Alps), science stands indebted for this memorable advance. Fedschenko showed that the embryos of Dracunculi, after quitting the human host, succeed in effecting an entry into the bodies of entomostracous crustaceans belonging to the genus Cyclops. Within these intermediary bearers, after twelve hours’ sojourn, the embryos undergo a change of skin, attended with subsequent growth. Here they remain to complete their larval development, which takes place within a period of five weeks, or, as Fedschenko himself told me, one month and six days. At length, as perfected larvæ, they are, together with their crustacean hosts, transmitted to the stomach of the ultimate or human bearer. It is probable that sexual maturity is next acquired within the human stomach, copulation following. After this, the females migrate to the situations in which they are found beneath the skin of the human bearer, whilst the males perish and pass out with the fæces. Thus much I gathered from M. Fedschenko himself when he visited this country, and I possess a sketch of the larvæ made by him at the time (October 23rd, 1873). One of the figures represents a larva which has undergone ecdysis, the long and narrow embryonic tail being supplanted by one which is blunt and forked at the tip. The somatic contents of the embryo have at the same time differentiated into a complete intestinal tube, and a constriction marks the junction of the œsophagus with the stomach. There is also internally an oval-shaped mass of cells near the centre of the body. These represent the commencement of the reproductive organs.

What I had gathered from Fedschenko in conversation thus epitomises that which has since been much more fully stated by Leuckart; and it is only fair to add that the Russian traveller was led up to his discovery by the previous investigations of Leuckart respecting the young of Cucullanus. The Leipsic helminthologist had, indeed, specially instructed Fedschenko as to the probable source of Dracunculus.

It is often thus that science makes its clear advances, since a master-mind is needed to set others on the right track. The embryos of Cucullanus and Dracunculus bear a close resemblance to each other, and the similarity of the types is continued on, though not in the same degree, in the next stage of larval growth, after ecdysis. The higher larvæ of both have their tails trifurcate at the tip, the head of the Dracunculus-larva being distinguished by the presence of a pair of papillæ. In the case of Cucullanus the embryos are, according to Leuckart, passively transferred to the stomach of Cyclops by the mouth; but in the case of Dracunculus, Fedschenko saw the embryo in the act of perforating the bodies of the little crustacea at the ventral surface, where the segments are bound together by a thin and easily penetrated connecting membrane. The larvæ then proceed to coil themselves within the limbs, as many as six or even a dozen of the parasites being occasionally found within the body of a single crustacean host. When they have reached full larval growth they measure about 1/25″ in length. Of course, after attaining this stage, it is a matter of conjecture as to the precise way in which their final destiny is accomplished. Fedschenko fed dogs and cats with the infected crustacea, but failed to rear Dracunculi in these animals. Clearly, these carnivora were unsuitable hosts. Could Fedschenko have experimented on man the result would probably have been very different. Arguing from what happens in the case of Cucullanus amongst fishes, and Trichina in man, there can be little doubt that all the further and final changes undergone by the larvæ are accomplished within the human host. These changes are usually, if not invariably, consequent upon a direct transference of the infested entomostraca along with water used as drink. Thus, it must at once be evident that the simple sanitary precaution of filtering water before use is amply sufficient to ensure the prevention of attacks of dracontiasis or the guinea-worm disease. The theosophical remedy of Moses against this invasion by fiery serpents, as the worms were called in his time, and the modern prophylactic measures dictated alike by science and common sense, thus stand in striking contrast the one to the other. In the nature of things it must ever remain that unreason and reason will select diametrically opposite methods of action, equally, no doubt, with the good intention of bringing about beneficial results.

From what has now been advanced, it will be seen that as regards the mode of infection the views categorically expressed in my previous work (‘Entozoa,’ p. 387) cannot be maintained. What, however, is there stated in respect of _treatment_ still holds good in the main, even as regards prophylaxis.

BIBLIOGRAPHY (No. 30).--_Adam_, ‘Trans. Med. and Surg. Soc.,’ Calcutta, 1824.--_Aitken, W._, ‘The Science and Practice of Medicine,’ 6th edit., vol. i, 1872.--(Anonymous), “Review of the writings and opinions of Duncan, Johnson, Bird, Mylne, Kennedy, Chisholm, H. Scott, A. J. Robertson, Smyttan, Macgregor, Thomas, Mosely, Morehead, Twining, and others, on the Dracunculus or Guinea-worm,” in ‘Corbyn’s India Journ. of Med. and Phys. Sci.,’ vol. ii, p. 118, 1836.--(Anon.), “The Guinea-worm very Prevalent at Bokhara,” ‘Boston Med. and Surg. Journ.,’ 1843, p. 387.--_Balfour, J._, ‘Ind. Ann. Med. Sci.,’ 1859, p. 175.--_Ballingall, G._ (l. c., supra), 1854.--_Bastian, H. C._, “On the Structure and Nature of the Dracunculus or Guinea-worm,” ‘Linn. Soc. Trans.,’ vol. xxiv, p. 101, 1863.--_Berncastle, J._, in the ‘Lancet,’ 1851.--_Bird, J._, ‘Calcutta Med. and Phys. Trans.,’ 1825, p. 151.--_Bremser_ (l. c., Bibl. No. 2), s. 194.--_Brett_, ‘Surgical Diseases of India,’ 1840; see also ‘Med.-Chir. Rev.,’ 1841.--_Bruce, N._, ‘Edin. Med. and Surg. Journ.,’ 1806, vol. ii, p. 145.--_Busk, G._, ‘Micr. Soc. Trans.’ (original series), 1846.--_Carter, H. J._, “Note on Dracunculus in the Island of Bombay,” ‘Bombay Med. and Phys. Soc. Trans.’ (new series), No. 2, p. 45, 1853-54; see also postscript, p. 252.--_Idem_, “Further Observ. on Dracunculus,” ‘Bomb. Med. and Phys. Soc. Trans.’ (new series), No. 4, p. 215, 1857-58.--_Idem_, “On Dracunculus and Microscopic Filaridæ,” ‘Ann. of Nat. Hist.,’ vol. iv (third series), 1859.--_Idem_, “Notes on Dracunculus,” &c., ‘Ann. of Nat. Hist.,’ vol. ix (third series), 1862.--_Chapotin_, ‘Bull. des Sci. Med.,’ 1810.--_Charvet_, ‘Ann. des Sci. Nat.,’ 1834.--_Chiaje_ (l. c., Bibl. No. 2), p. 99.--_Chisholm, C._, “On the _Malis Dracunculus_ or Guinea-worm (in Grenada),” ‘Edin. Med. and Surg. Journ.,’ vol. xi, 1815; see also the ‘Veterinarian,’ vol. ix, p. 508, 1836.--_Clark_, ‘Med.-Chir. Rev.,’ 1840.--_Clarkson, N. F._, “Alleged Case in the Horse,” the ‘Veterinary Record,’ 1845, p. 73.--_Clot-Bey_, ‘Aperçu sur le ver dragonneau observé en Egypte,’ 1830.--_Cobbold_, ‘Entozoa,’ p. 373.--_Cuvier_, ‘Règne animal,’ Orr’s Eng. edit., 1849, p. 644.--_Davaine_, ‘Traité,’ l. c., edit. ii, p. 783 (full lit. refs.), 1878.--_Dickson_, ‘Path. Soc. Trans.,’ 1851.--_Drummond_, ‘Med. Commentaries,’ 1793, p. 294.--_Dubois_, ‘Edin. Med. and Surg. Journ.,’ vol. ii, 1806.--_Duncan_, ‘Calcutta Med. and Phys. Soc. Trans.,’ 1835.--_Ewart, J._, “Questions relating to Dracunculus,” in a review of his memoir on the “Vital Statistics of the Meywar Bheel Corps,” in the ‘Madras Quart. Journ. of Med. Sci.,’ vol. i, 1860, p. 462.--_Fedschenko_, ‘Protocol of the Promoters (Freunde) of the Natural and Physical Sciences at Moscow’ (in the Russian language), 1869 and 1874 (quoted by Leuckart).--_Forbes, D._, “Observ. on Dracunculus” (extr. from the ‘Half-yearly Reports of the diseases prevailing at Dharwar in the 1st Grenadier Regiment, in the year 1836’), ‘Bombay Med. and Phys. Soc. Trans.,’ vol. i, 1838, p. 215.--_Gibson, A._, “Note on the Prevalence of Dracunculus,” in his remarks on the “Diseases of the Deckan,” in ‘Bomb. Med. and Phys. Soc. Trans.,’ vol. ii, 1839, p. 209.--_Gramberg_, ‘Geneeskundige tijdschrift voor nederl. Indie,’ 1861, p. 632 (quoted by Leuckart).--_Greenhow, H. M._, ‘Indian Ann. of Med. Sci.,’ vol. vii, 1861, p. 31.--_Grierson, D._, “Observ. on the Dracunculus, as it prevailed in the 22nd Regiment, N.I., from April till September, 1841,” ‘Bomb. Med. and Phys. Soc. Trans.,’ No. 4, 1841, p. 90.--_Grundler_, in ‘Commerc. Litt. Nov.,’ 1740, p. 239.--_Henderson, J._, “Note respecting Four Cases of Dracunculus in the 48th Regiment,” ‘Madras Quart. Journ.,’ vol. iii, 1841, p. 353.--_Horton, J. A. B._, ‘Army Med. Reports,’ 1868, p. 335.--_Kennedy, R. H._, ‘Calcutta Med. and Phys. Soc. Trans.,’ 1825, p. 165.--_Küchenmeister_ (l. c., Eng. edit.), p. 389.--_Leuckart_ (l. c., Bibl. No. 1), s. 644-725.-- _Lewis, T. R._, in ‘On a Hæmatozoon,’ &c. (l. c., Bibl. No. 23), p. 30 _et seq._--_Lima, Da S._, “Remarks on the _Filaria medinensis_, or Guinea-Worm; on the occurrence of this Parasite endemically in the Province of Bahia; on its entrance into the human body by drinking water,” in the ‘Veterinarian,’ Feb., March, _et seq._, 1879.--_Lister_, ‘Phil. Trans.,’ 1690, p. 417.--_M’Clelland, J._, ‘Calcutta Journ. of Nat. Hist.,’ vol. i, 1841, p. 366.--_M’Grigor, J._, “On the Guinea-worm” (in his “Account of the Diseases of the 88th Regiment in Bombay”), ‘Edin. Med. and Surg. Journ.,’ vol. i, 1805, p. 284.--_Morehead, C._, ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. vi, 1833, p. 418; also noticed in ‘Edin. Med. and Surg. Journ.,’ vol. xliv, 1835.--_Idem_, part ii, ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. viii, 1836-42.--_Murray, J._, “Guinea-worm a very Common Disease at Sattara” (in his Official Report on the Hospital, &c.), ‘Bombay Med. and Phys. Soc. Trans.,’ No. 9, art. vi, p. 198, 1847.--_Oke, W. S._, “Case of Guinea-worm,” ‘Prov. Med. and Surg. Journ.,’ vol. vi, 1843.--_Oldfield_, “Case of Dracunculus” (from Laird and Oldfield’s “Narrative of an Expedition into the Interior of Africa”), ‘Dublin Journ.,’ vol. xii, 1838.--_Paton_, “Cases of Guinea-worm,” ‘Edin. Med. and Surg. Journ.,’ vol. ii, 1806.--_Raddock_, “A Case of Guinea-worm,” ‘Indian Med. Gaz.,’ Oct., 1877, p. 265.--_Scott, W._, “Remarks on the Dracunculus,” in a letter to the Medical Board, Madras, ‘Edin. Med. and Surg. Journ.,’ vol. xvii, 1821.--_Leverance, C. E._, “History of a Case of Guinea-worm,” from ‘Amer. Med. Times,’ in the ‘Glasgow Med. Journ.,’ vol. ix, 1861-62, p. 377.--_Smyttan, G._, “On Dracunculus,” ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. i, 1825, p. 179.--_Stewart, L. W._, ‘Indian Ann. of Med. Sci.,’ vol. vi, 1858, p. 88.--_Twining, W._, “Cases of Dracunculus,” ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. vii, 1835.

_Oxyuris vermicularis_, Bremser.--Of all the parasites infesting the human body this is the one concerning which the medical practitioner is most frequently consulted, partly on account of its remarkable frequency in children, and more particularly on account of the difficulty often experienced in getting permanently rid of it. The _Oxyuris vermicularis_ is by no means confined to young persons, seeing that adults are infested even to old age. It is familiarly known as the threadworm or seatworm. The male measures about 1/6″, and the female from 1/3″ to 1/2″ in length. The female possesses a long capillary tail, which terminates in a three-pointed end. The extremity is said to act as a kind of holdfast. The tail of the male is obtusely pointed. In both sexes the body presents a more or less fusiform shape, the anterior end being narrowed to form a somewhat abruptly-truncated head, which is often rendered very conspicuous by a bulging of the transparent integument surrounding the mouth. This presents in profile the aspect of winged appendages (fig. 45). The oral opening is tripapillated, leading into a triangular œsophagus. The integument is transversely striated, and of a silvery-white appearance. The spicule is simple, single, and very minute. The eggs are oblong and unsymmetrical. They measure about 1/900″ from pole to pole, and 1/1400″ transversely.

Many years back (1863) I pointed out that the most advanced eggs whilst still within the body of the pregnant female contained tadpole-shaped embryos, and about the same time the fact was noticed by Claparède. In his beautiful and scholarly memoir, ‘De la formation et de la fécondation des œufs chez les vers Nématodes,’ he wrote concerning the ova as follows:--“The egg, which exhibits the form of a very narrow disk in the ovary, acquires the shape of an elongated ellipsoid in the oviduct, and at the surface differentiates itself into a very thick vitelline membrane. Then it forms a strong and resisting chorion, which imparts to the egg an outline similar to that of a bridge’s span. It has an oval figure flattened at one of its sides. This chorion is very fragile; it frequently gives way under slight pressure from the thin plate of glass which covers the object. It extends itself considerably under the action of acetic acid, acquiring a size three or four times greater than that of the egg. The constitution of this chorion is perfectly identical in the eggs both before and after impregnation. It is, nevertheless, easy at first sight to know whether or not we have to deal with a fecundated egg. In the impregnated females the uteri are filled with thousands of ova, each one of which encloses an embryo already well formed. The ventral surface of the embryo and the tail are, without exception, applied to the flattened side of the egg. The embryo is very broad in the body, and occupies all the interior space. An embryo such as Küchenmeister has represented under the form of a small filiform worm folded on itself, and only occupying a very small part of the cavity of the egg, is never to be seen. In the non-fecundated females, on the other hand, the uteri are filled with eggs, which, instead of the embryo, enclose a non-segmented yolk furnished with a large germinal vesicle. This vesicle is not visible so long as the eggs have the form of thin disks; it only shows itself when the eggs begin to acquire an elliptical form in the oviduct. It is, however, probable that this vesicle is the same which was originally visible in the ovary.” The chorion itself is homogeneous, but in an allied species (_Oxyuris spirotheca_) Gyoery and Claparède found that this egg-covering consists of spirally-coiled bands resembling the tracheal spiral fibre of an insect. Under suitable conditions the tadpole-shaped embryos rapidly assume a vermiform character. The investigations of Leuckart have shown that “one only needs to expose the eggs to the action of the sun’s rays in a moistened paper envelope when, at the expiration of five or six hours, the tadpole-shaped embryos will have already become slender elongated worms.” According to Heller, the simplest way to rear the vermiform stage of Oxyuris is to put a number of the eggs in a glass tube filled up with saliva. The tube should then be placed in the arm-pit, in which situation it can be carried about with little inconvenience. In a few hours the transformations will commence and go on continuously until the vermiform condition is attained. If, as remarked in my ‘Lectures,’ it be asked whether the embryos which have escaped into the bowel are capable of arriving at the vermiform stage, the answer is in the affirmative; for, as Leuckart says, “the elongated embryos are to be found not only in the fæces but also in the mucus of the rectum above and around the anus.” Vix has also asserted that free vermiform embryos are occasionally to be detected in the intestine of the human bearer along with the eggs; this hatching within the lower bowel, however, must, in my opinion, be regarded as exceptional. Heller is of the same opinion. According to Leuckart, the escape of the embryos from the eggs “ordinarily takes place under the action of the gastric juice, also primarily in that condition when they have by some means or other gained access to a new bearer.” Prof. Leuckart and three of his pupils courageously infected themselves by swallowing the eggs, and had the satisfaction of observing young Oxyurides in their stools fifteen days afterwards.

From the united labors of Professors Zenker and Heller it is now rendered certain that all the further changes necessary to bring the larvæ to sexual maturity are accomplished within the small intestines of the human bearer; and it is not necessary that a change of hosts should occur at any time during the life of the parasite. Infection ordinarily takes place by the accidental and direct conveyance of the eggs that are lodged in the neighbourhood of the victim’s anus to the mouth. Since the victim may accomplish this during sleep, it is not in all cases fair to charge infected persons with uncleanliness. On the other hand, it too often happens that due care in this respect has not been exercised, and from such persons you may remove the eggs of Oxyurides from the margins of the finger nails. One aristocratic person, who was infested by myriads of these entozoa, confessed to me that in his extreme distress, and consequent rage, he had freely bitten the live worms in halves between his teeth. He had thus exposed himself to a terrible revenge, since multitudes of the ova entering his mouth subsequently found their way into the stomach and intestines. By whatever mode the eggs are conveyed to the mouth their subsequent passage to the stomach ensures their being hatched. In the duodenum and other divisions of the small intestines, as Zenker and Heller have shown, the embryos undergo transformation, casting their skins, and growing with great rapidity. Probably not more than three weeks or a month is necessary to complete their growth. Heller obtained mature worms from an infant only five weeks old. Finally the worms are transferred to the cæcum, which constitutes, so to speak, their headquarters. It is an error to suppose that the lower bowel or rectum forms their especial habitat, nevertheless the most approved manuals, vade mecums, and general treatises have for a long time supported this erroneous view. The error had been pointed out by Stricker in 1861.

The symptoms produced by Oxyurides are occasionally very serious. In the mildest cases they have a tendency to undermine the health. As remarked in my ‘Entozoa,’ the unpleasant sensations chiefly develop themselves in the evening and at night, consisting for the most part of feelings of heat and irritation within and around the margin of the anus. The symptoms may become extremely distressing and almost intolerable, especially when the itching extends to the genito-urinary passages, in consequence of the escape and migration of the parasites about these parts. By-and-by various sympathetic phenomena, such as restlessness, general nervousness, itchings at the nose, involuntary twitchings, grinding of the teeth during sleep, chorea, convulsions, and even epileptiform seizures, may supervene. At the age of puberty special local disorders arise, the nature of which will be readily understood when merely spoken of as the morbid phenomena of sexual irritation. In the female the occurrence of pruritus and leucorrhœa is not uncommon, accompanied or not, as the case may be, with hysteria in various forms. There is usually general asthenia, with more or less emaciation. The anæmia is sometimes remarkable, but in place of anorexia, which is, however, an occasional symptom, one frequently finds a most voracious appetite, especially in young people. Sometimes there are obscure symptoms simulating those of local organic disease.

About the treatment of the disorder I have nothing to say here, further than to urge the benefits of the preventive measure of cleanliness. Like Zenker and Heller, I have obtained the eggs of oxyurides from beneath the finger-nails of young people. In one lad all the nails had been carefully bitten down to their roots, but from beneath a minute projecting portion that was left on the right fourth-finger I procured two eggs. Their demonstration under the microscope convinced both parent and child of the necessity of frequently employing local and general ablutions. Personal cleanliness is essential. In this connection an able biologist has ventured to hazard a statement to the effect that “probably any infected person who adopted the requisite precautions against reinfection from himself or others would get well in a few weeks without treatment by drugs.” Dr Ransom bases his belief on the known facts of the life-history of this entozoon, as recorded more especially by Leuckart. I regret that I cannot fully share Dr. Ransom’s views, and still less should I think it right by my silence to seem to endorse his statement to the effect “that every person who is shown to be infested with those very common entozoa, _Oxyuris vermicularis_ and _Trichocephalus dispar_, is thereby demonstrated to have swallowed minute portions of his own or another person’s fæces.” This is putting the case too strongly. No doubt the eggs of oxyurides swallowed by ourselves must have previously passed through some person’s rectum; as such, either separately or mayhap collectively, in the body of the maternal parasite. That does not, however, justify the statement, that we “have swallowed” part of our own or of some other person’s excrement. The eggs ought not to be regarded as constituent portions of the fæcal matter. Perhaps Dr Ransom will say that the surfaces of these eggs, being in contact with fæcal matter, must carry infinitesimal particles on their surfaces, and it is to such that he refers. As, however, a large proportion of the ova escape with their parents, whilst they are still lodged within the maternal worm, it cannot be held that these intra-uterine ova carry fæcal matter on their shells. Commonly the eggs are swallowed in the separate, free, and dry state. In water they perish quickly. The act of eating with unwashed hands is a fertile source of infection, more especially if the meal be taken either in bed or in the bedroom.

BIBLIOGRAPHY (No. 31).--_Alexander, J._, “On Vermination,” ‘Lancet,’ 1833.--_Anderson, W._, “On Santonine, with especial reference to its use in Roundworm and Threadworm,” ‘Brit. Med. Journ.,’ April, 1864, p. 443; also in Braithwaite’s ‘Retrospect of Medicine,’ vol. xlix (synopsis, p. 20), 1864.--_Barry, J. M._, “On the Origin of Intestinal Worms, particularly the _Ascaris vermicularis_,” ‘Trans. Assoc. of Fell. and Licent. of King’s and Queen’s Coll. of Phys. in Ireland,’ vol. ii, 1878, p. 383.--_Bremser_, l. c., s. 79.--_Buckingham_, “Ascarides causing Erotomania,” from ‘Bost. Journ., U.S.,’ in ‘Med. Gaz.,’ 1857.--_Claparède, E._, “On the Formation of the Egg and Fertilisation in the Nematoidea,” from the ‘Zeitsch. f. w. Zool.,’ translated by Dallas in ‘Ann. Nat. Hist.,’ vol. i (third series), 1858.--_Idem_ (memoir quoted in the text above), Genève, 1859.--_Cobbold, T. S._, ‘Worms,’ Lect. xii-xv, 1872.--_Idem_, ‘Entozoa,’ p. 362.--_Idem_, ‘Brit. Med. Journ.,’ Aug., 1873.--_Idem_, ‘Tapeworms and Threadworms,’ 2nd edit., 1872.--_Idem_, ‘Lancet,’ 1866.--_Idem_, “On the Development and Migrations of the Entozoa,” ‘Brit. Assoc. Rep.,’ 1864, p. 116.--_Date, W._, ‘Lancet’ for Feb., 1872, p. 185.--_Davaine_, ‘Traité,’ l. c., 2nd edit., p. 211, and ‘Synops.,’ p. 95.--_Dickinson_, “Case of Epilepsy in Children relieved by the expulsion of Worms,” ‘Med. Times and Gaz.,’ Jan., 1863.--_Dickson, R._, art. “Anthelmintics,” rep. from the ‘Penny Cyclopædia,’ in Knight’s ‘Eng. Cyclop. Arts and Sci. Div.,’ vol. i (column 365), London, 1859.--_Dreyfus_, “Irritation of the Bladder from Ascarides,” from ‘Journ. de Med.,’ in ‘Lond. Med. Gaz.,’ 1847.--_Elliotson, J._, “A Lecture on Worms,” ‘Lond. Med. Gaz.,’ 1833.--_Idem_, “On Worms in the Intestinal Canal,” ‘Lancet,’ 1831.--_Idem_, “On a Case of Threadworms,” ‘Lancet,’ 1831.--_Idem_, “On Intestinal Worms,” ‘Lancet,’ 1830.--_Heller, A._, “Darmschmarotzer,” in von Ziemssen’s ‘Handbuch,’ Bd. vii, s. 632 (see also Anglo-American edit.), 1876.--_Küchenmeister_, l. c., Eng. edit., p. 356.--_Ransom_, in Reynolds’ ‘Dictionary of Medicine.’--_Smith, A._ (and others), ‘Lancet,’ April 29th, 1865, p. 468.--_Stricker, W._, in ‘Virchow’s Archiv,’ xxi, 1861, s. 360.--_Tatham_, ‘Lancet,’ April, 1867, p. 457; see also p. 519.--_Vix, E._, ‘Ueber Entozoen,’ &c., Berlin, 1860; see also “On the occurrence of Entozoa in the Insane, particularly with respect to the _Oxyuris vermicularis_;” brief notice (‘Allg. Zeitsch. f. Psychiatrie’) in Winslow’s ‘Journ. of Psycholog. Med.,’ vol. i, 2nd series, 1861, p. 158.--_Zenker_, ‘Verhandl. d. phys. med. Soc.,’ H. ii, Erlangen, 1870, s. 20; and in ‘Tageblatt der deutschen Naturforscherversammlung zu Dresden,’ 1868, s. 140 (also quoted freely by Leuckart, Davaine, and Heller).

_Leptodera_ (_Anguillula_) _stercoralis_, Bavay.--In the summer of 1876 Dr Normand, of the French Marine, discovered this little entozoon in the fæcal discharges of soldiers who had been sent home invalided from Cochin-China. The patients in question were the victims of the so-called Cochin-China diarrhœa or dysentery. This disorder is endemic in character, and it had hitherto been regarded as consequent upon a variety of causes other than parasitic. Dr Normand’s discovery, as such, therefore takes equal rank with the analogous revelations made by Bilharz, Harley, Leuckart, Zenker, Weber, Lewis, and Bancroft, in respect of the particular helminthiases in man with which their names are severally associated (Bilharzia disease, Endemic hæmaturia, Cestode tuberculosis, Olulaniasis, Inter-tropical anæmia, Trichinosis, Lymphoid affections, Helminthoma, and so forth), and also, if I may be permitted to say so, with my own determinations in respect of a variety of endemics affecting animals (cestode and nematode epizoöty in the horse, the so-called grouse-disease, the pigeon-endemic due to lumbricoids, &c.).

The _Leptodera stercoralis_ is a minute, smooth-bodied, simple, rhabditiform nematode, measuring when full grown 1/25″ in length, with an average breadth of 1/625 of an inch. The embryos at the time of their extrusion measure only 1/250″ in length, but by the time at which a rudimentary vesicle representing the uterus begins to form, the females have already attained a length of about 1/83″. The males and females are of nearly equal size. The transition from the embryonal state to the higher larval conditions is accompanied by a change of skin, after which the digestive and reproductive organs are gradually but rapidly formed and completed. These changes have been minutely traced and recorded by Professor Bavay, who also compares the entozoon with the genera Rhabditis and Leptodera, in either of which genera the worm might be placed. I have accordingly adopted the nomenclature suggested by Bavay.

As happens in all the kindred helminthiases that are known to be dependent upon the presence of small worms, large numbers of Anguillules are necessary to produce injurious effects upon the bearer. Thus, the evacuations of the Cochin-China patients were found to contain such multitudes of the worms that their numbers could only be adequately estimated at so many hundreds of thousands passed in twenty-four hours. Of course they varied in quantity, not only in different patients, but in the same bearer, from day to day. They are to be found in every stage of growth and development, from that of the intra-ovular embryo and free embryonic state up to sexual maturity. They occupy all parts of the intestinal canal, from the stomach downwards, being also found in the pancreatic and biliary ducts, and likewise within the gall-bladder. According to Bavay, five days suffice under favorable circumstances for the complete maturation of the worm. This readily accounts for their occasional extreme abundance.

I am indebted to the courtesy of Dr le Roy de Méricourt for the original memoirs from which these brief abstracts are taken.

_Leptodera intestinalis_, Bavay.--This is a larger species, now and then found associated with the above, and, according to Bavay, “in infinitely less abundance.” This species was also discovered by Dr Normand, and has been carefully described by Bavay. Possibly the worm may afford us another curious instance of dimorphism. Be that as it may, it must be provisionally regarded as a distinct form. As its occurrence is by no means invariable, its rôle in relation to the Cochin-China diarrhœa must, as Davaine has likewise remarked, be regarded as of secondary importance. It is readily distinguished from _A. stercoralis_ both in the adult and larval conditions. The full grown worm, although comparatively narrow, is more than twice as long as its congener; moreover, the larvæ, in place of possessing finely-pointed tails, have blunt or truncated caudal extremities. Converting M. Bavay’s millimetric measurements into fractions of the English inch, the average length of the mature worms will be about 1/11″, whilst their breadth does not exceed 1/757″ in diameter.

BIBLIOGRAPHY (No. 32).--_Bavay_, “Sur _l’Anguillule stercorale_,” ‘Comptes Rendus,’ Oct., 1876, p. 694, also in ‘Ann. Nat. Hist.,’ vol. xviii, 4th series, p. 507, 1876, also noticed in the ‘Veterinarian,’ Jan., 1877, p. 19.--_Idem_, “Note sur _l’Anguille intestinale_,” ‘Archiv. de Méd. Nav.,’ July, 1877, p. 64, and in ‘Ann. Nat. Hist.,’ 1877, vol. xix, 4th series, p. 350.--_Cobbold, T. S._, “Parasites of Man,” in the ‘Midland Naturalist’ for January 1st, 1879.--_Davaine_, ‘Traité,’ l. c., 2nd edit., Supp., pp. 966-976, 1877.--_Laveran_, in ‘Gaz. Hebd. de Med.,’ Jan., 1877, p. 42.--_Layet_ and _Le Roy de Méricourt_, in ‘Dict. Encycl. des Sci. Med.,’ 1875.--_Libermann_, in ‘Gaz. des Hôp.,’ March, 1877, p. 237, and in ‘La France Méd.,’ 1877, p. 165 (quoted by Davaine).--_Méricourt_ (see Layet).--_Normand, A._, in ‘Comptes Rendus’ for July, 1876, p. 316, and Aug., 1876, p. 386.--_Idem_, in ‘Arch. de Méd. Navale,’ 1877, p. 35, and separately as ‘Mémoire sur la diarrhée dite de Cochinchine,’ Paris, 1877.--_Idem_, “Du rôle étiologique de l’Anguillule dans la diarrhée de Cochinchine,” in ‘Archives de Médecine Navale’ for September, 1878, pp. 214-224.

_Ascaris mystax_, Rudolphi.--This well-known helminth possesses aliform appendages, one on either side of the head. It is of a medium size, the male measuring 2-1/2″ and the female usually 3-1/2″ to 4″ in length. Both as regards the size of the alæ and the length of the body it varies in different hosts. Thus the variety infesting the dog has long been regarded as a distinct species (_A. marginata_), partly from the circumstance that the alæ are less conspicuous, and partly because the individuals are often longer and thicker. I possess one specimen from the dog measuring more than six inches in length. From like causes the _Ascaris leptoptera_ and other varieties infesting the carnivora have been regarded as distinct species, but the worm also varies in one and the same host.

As remarked in my elementary treatise, the late Dr Bellingham, of St Vincent’s Hospital, Dublin, published in the 13th vol. of the ‘Annals of Natural History,’ an extended catalogue of Irish entozoa, and in this list he recorded the existence of a new round worm in man. He says of it:--“From the distinctness of the lateral membranes of the head I have given it the name of _Ascaris alata_.” The catalogue was constantly referred to by Dujardin, Diesing, and other systematists; but some of the continental helminthologists do not appear to have had access to Dr Bellingham’s more extended account of this parasite as given in the first volume of the ‘Dublin Medical Press,’ No. 7, Feb. 20th, 1839. I am led to this inference from the doubt which some have cast upon the very existence of the worm, although others, with more candour, supposed that Bellingham had only mistaken the species. Thus, Küchenmeister (‘Parasiten,’ s. 464, and in Lancaster’s edit., vol. ii, p. 100) says:--“The _Ascaris alata_, found in the small intestines of a man, is probably only a young individual of one of the long-known nematoda, _if, indeed, it be a worm at all_!” (The italics are mine.) This statement was reproduced by Hulme in his English edition of Moquin-Tandon’s ‘Elements of Medical Zoology,’ p. 341; and the French author himself evidently shared the doubt expressed by other people. Dujardin (‘Helminthes,’ p. 156) admitted the species, as also did Diesing (‘Systema Helminthum,’ p. 175), but the latter unluckily added the following very significant suggestion:--“An _Ascaris lumbricoides_ capitis epidermide emphysematice inflata?”

Dr Leidy, of Philadelphia, admitted _A. alata_ among his _Entozoa hominis_ without comment (‘Smithsonian Contrib.’ for April, 1853), but Weinland, of Frankfort, in his list, prefixed a note of interrogation, observing also that it had been “once” found in Ireland (‘Essay on Tapeworms,’ p. 88). It is quite clear, therefore, that these authors did not believe that the _Ascaris mystax_ was a human parasite. Those who doubtfully accepted Bellingham’s _A. alata_ did so under the impression that whatever it was, it could not be regarded as the common Ascaris of the cat. In the new edition of Davaine’s ‘Traité,’ _A. alata_ is, to my surprise, still retained as a separate species, and there is no mention of the occurrence of _A. mystax_ in man. From what has recently been written by several continental helminthologists (Leuckart, Heller, and others), I rejoice to think that it is not necessary for me again to advance the really superabounding proofs that Bellingham’s _A. alata_ was nothing more than _A. mystax_. It has at length been admitted by almost all who are competent to form an opinion, that the memoir originally communicated to the ‘Lancet,’ in 1863, and subsequently introduced into the text of my introductory work, finally settled the question of identity. It was through the donation of Dr Edwin Lankester and Mr Scattergood that I was enabled at the time to announce the _third instance_ of the occurrence of this parasite in man, and since that date several other instances have been brought under public notice. Not less than seven cases have now been noticed in which this little lumbricoid of the cat and dog has been found in man. For one good human specimen I am indebted to Dr Morton. In the above list I include Heller’s specimen, and the one from Greenland sent by Steenstrup to Leuckart. According to Hering’s observations this worm grows with remarkable rapidity. Worms obtained from a puppy only six days old measured from 1/12″ to 1/6″ in length. In a twelve-day-old puppy they reached nearly an inch in length, and in a month the growth was up to four inches. Females only 1-1/2″ in length already contained eggs, and males only 3/4″ long had acquired their spicules. Three weeks therefore, would be amply sufficient for the completion of sexual maturity within the feline or canine host. We do not know, however, whether or not a temporary host is necessary for the larvæ prior to their introduction into the cat or dog. Hering thinks that a direct infection by the ova is sufficient; but he gives no proof of the truth of this hypothesis. “Leuckart (as quoted by Heller, l. c., s. 615) found numerous embryonal round worms in the stomach of a cat, 1/62″ in length, and in addition all the intermediate stages of growth up to the larger examples found in the small intestine. They remain in the stomach until they have attained a length of from 1/18″ to 1/12″ and then pass into the small intestine. When they have attained a length of nearly 1/8″ they cast their skins and change the tooth-like boring apparatus for the three characteristic semicircular lips. These observations on _Ascaris mystax_ (adds Heller) render it probable that _A. lumbricoides_ is also introduced into the human alimentary canal while still in the embryonal state or somewhat further advanced (und wohl auch grösse).” The subject will be found more fully discussed in my account of the large species further on. The cat’s worm possesses an historical interest, not only in connection with Bellingham’s original discovery, but also in respect of Nelson’s subsequent determinations as to the precise mode of impregnation in nematodes. The subject is too extended and too special to be dealt with here at any great length.

For several years after Nelson left the shores of England to spend a too short life in New Zealand, the points discussed in his ‘Edinburgh Thesis’ (and subsequently published in the ‘Philosophical Transactions’) formed the subject-matter of numerous memoirs contributed to the leading German scientific journals. Stated with brevity, it may be said that, according to Nelson, the essential act of impregnation occurs when the thimble-shaped spermatozoa of the male penetrate the unimpregnated or ovarian ovum. This, he maintained, could and did take place at any part of the surface of the unfertilised ovum, since the granular mass of which it was composed, though well defined, did not, at this period, possess a limiting--or true yolk--membrane. Professor Allen Thomson, in a series of papers (some contributed in the German language), supported Nelson’s views generally.

Amongst Nelson’s chief opponents was Meissner, who demonstrated that the unimpregnated ova really possessed a delicate limiting membrane, and that consequently the action of the spermatozoa was restricted to that portion of the ovarian ovum which became exposed by rupture or separation from the rachis. This opening he termed the micropyle. The union of the sexual elements is quickly followed by a condensation of the yolk-granules, and by the disappearance of the hitherto centrally placed germinal vesicle. The ovum next assumes a distinctly oval shape, the true yolk-membrane and the external chorional envelope now becoming more and more differentiated, until the latter acquires a regularly tuberculated surface. Co-ordinating with these changes the granular yolk is seen transforming itself into a single large embryonal cell; after a time this cell divides and subdivides by the ordinary process of yolk-segmentation, until it is finally resolved into the condition of a short, stout, vermiform embryo. The egg having assumed its definitive oval shape, the intrachorional embryo remains coiled within the shell, and does not make its escape until the egg has passed from the body of the parent worm.

Into the question of the mode of formation of the ovarian ova, and also into that of the development of the spermatozoa, I do not enter. However unwillingly, I must, in this matter, be contented to refer to Professor Allen Thomson’s classical article ovum (quoted below), to Leuckart’s elaborate analysis (l. c., Bd. ii, s. 76-92), and also, especially, to the exhaustive memoir of Claparède, whose brilliant labors, like those of Henry Nelson, were too early terminated by death. Shortly after graduation Nelson suffered a virtually enforced banishment from his native land.

BIBLIOGRAPHY (No. 33).--_Bellingham, O. B._, “On the Genus to which the Worms known as Ascarides belong,” ‘Dublin Journ.,’ vol. xiv, 1839.--_Idem_, “Catalogue of Irish Entozoa,” ‘Ann. of Nat. Hist.,’ vols. xiii and xiv, 1843-44; and in the first part of Charlesworth’s ‘Mag. of Nat. Hist.,’ vol. iv, 1840. See also the address by Dr E. D. Mapother on the “Lives and Writings of O’Ferrall and Bellingham,” in the ‘Dubl. Journ. of Med. Sci.,’ Nov., 1877, p. 471 _et seq._--_Bischoff_, ‘Widerlegung (u. s. w.),’ Giessen, 1853; quoted by Claparède, l. c. _infra_, p. 9.--_Idem_, ‘Bestätigung (u. s. w.),’ Giessen, 1864.--_Idem_, “Ueber Ei-und Samenbildung und Befruchtung bei _Ascaris mystax_,” Sieb. and Köll. ‘Zeitsch.,’ 1855, s. 377; also in S. and K. ‘Zeitsch.,’ 1856.--_Bremser_, ‘Icones helminth.,’ p. 23, tab. iv.--_Claparède, E._, “Ueber Eibildung und Befruchtung bei den Nematoden,” S. and K. ‘Zeitsch.,’ 1857, s. 106.--_Idem_, ‘De la formation et de la fécondation des œufs chez les vers Nématodes,’ Genève, 1859. See also ‘Ann. of Nat. Hist.,’ vol. i, 3rd series, 1858.--_Cobbold_, in ‘Proceed. of the Zoological Soc. of London,’ Nov., 1862.--_Idem_, ‘Brit. Assoc. Rep.,’ 1862.--_Idem_, “On the occurrence of _Ascaris mystax_ in the Human Body,” with figures, ‘Lancet,’ Jan., 1863; and in the ‘Dublin Med. Press,’ Feb., 1863.--_Idem_, ‘Entozoa,’ chap. xi, p. 316, 1864.--_Idem_, ‘Worms,’ pp. 72 and 112, 1872.--_Idem_, in “Obituary Notice of Dr Henry Nelson,” ‘Med. Times and Gaz.,’ 1865 (?).--_Davaine_, ‘Traité,’ l. c., 1877.--_Diesing, C. M._, ‘Syst. Helm.,’ vol. ii, p. 180, 1850.--_Dujardin_ (l. c., Bibl. No. 2), p. 162.--_Frœlich_, in ‘Naturf.,’ xxiv, s. 141 (_Asc. felis_).--_Funke, O._, ‘Lehrbuch (u. s. w.),’ 1857, s. 1299.--_Gmelin_, ‘Syst. Nat.,’ p. 3031.--_Golze_, ‘Naturg.,’ l. c., s. 79.--_Gurlt_, ‘Path. Anat.,’ s. 366.--_Heller, A._, “Darmschmarotzer,” in Von Ziemssen’s ‘Handbuch,’ Bd. vii, s. 361.--_Idem_, ‘Sitzungsb. d. Erlanger phys.-med. Soc.,’ 1872, s. 73.--_Hering_, “Ueber das Vorkommen und die Entwicklung der _Ascaris mystax_ bei jungen Hunden,” quoted by Leuckart from ‘Würtemb. Naturw. Jahreshefte,’ 1873, s. 305-337.--_Kölliker_, in ‘Müller’s Archiv,’ 1843, s. 68 _et seq._--_Leidy_, ‘Proc. Acad. Phil.,’ viii, p. 50.--_Leuckart_, l. c., Bd. ii, s. 258.--_Meissner, G._, “Beobachtungen über das Eindringen der Samenelemente in den Dotter,” S. and K. ‘Zeitsch.,’ 1854, s. 208.--_Morton, T._, “Another Example of the Occurrence of _A. mystax_, from a Child of fourteen months old,” in a letter to the ‘Lancet,’ March 11th, 1865, p. 278.--_Nelson, H._, “On the Reproduction of _Ascaris mystax_,” ‘Proc. of the Royal Soc.,’ in ‘Philosoph. Trans.,’ and in ‘Med.-Chir. Rev.,’ 1051-52; also in ‘Froriep’s Tagsbericht.,’ 1852, s. 205-207.--_Rudolphi_, ‘Synops.,’ p. 42, 1819.--_Schneider_, “Ueber Bewegung an dem Samenkörperchen der Nematoden,” in ‘Monatsb. d. Berliner Akad.,’ 1856, s. 192.--_Idem_, ‘Monographie der Nematoden,’ Erste Abth., s. 38, und Dritte Abth., s. 263 (“Entwicklungsgeschichte”), 1866.--_Siebold_, ‘Vergleichende Anatomie,’ 1848, s. 153, and in Burnett’s edit., p. 125 _et seq._, 1854.--_Thomson, A._, art. “Ovum,” in ‘Todd’s Cyclop. of Anat. and Phys.,’ supp., 1859.--_Idem_, “Ueber die Samenkörperchen, die Eier und die Befruchtung der _Ascaris mystax_,” S. and K. ‘Zeitsch.,’ 1856, s. 425.--_Idem_, “Report of Glasgow Meeting” (‘Brit. Assoc. Rep.’), 1855, p. 158.

_Ascaris maritima_, Leuckart.--This is a well-marked species. Judging from the characters presented by the solitary, sexually-immature female which supplied Leuckart with his only means of diagnosis, this worm may be briefly described as a filariform nematode about 3/4″ in length and about 1/25″ in breadth. Although there are no cephalic aliform membranes, the cuticle immediately below the lips forms small and distinct projections, one on either side of the head (‘Die Mensch. Par.,’ Bd. ii, s. 877).

This entozoon was discovered by Dr Pfaff at Jacobshavn, near Godhavn, West Greenland, in April, 1865. Two years later he sent the specimen to Krabbe, who afterwards transmitted it to Leuckart. In the original communication addressed to the Copenhagen helminthologist, Dr Pfaff states that he procured the worm from amongst matters vomited by a child, and he incidentally observes that he had hitherto encountered only _Bothriocephalus cordatus_ and _Oxyuris vermicularis_ amongst Greenlanders. As to the source of infection, Prof. Leuckart not unnaturally refers to the similar conditions of existence shared by the human and carnivorous inhabitants of that country. It is well known that bears, polar-bears, seals, and walruses are largely infested by nematodes (_Asc. transfuga_, _A. osculata_, _Ophiostoma dispar_, &c.), but these various species are quite distinct from Dr Pfaff’s little “spulwurm.”

_Ascaris lumbricoides_, Linneus.--This common parasite was for a long while regarded as identical with the great lumbricoid of the horse, but the question has been finally settled by Schneider, who has shown that the human worm, although identical with Dujardin’s _Ascaris suilla_ of the hog, is nevertheless quite distinct from the _Ascaris megalocephala_ of solipeds. The large lumbricoid occasionally found in the ox belongs to the human worm. Our large human helminth resembles the common earth-worm in general appearance only. The males usually measure from four to six inches in length, and the females from ten to fourteen inches. Some have been reported up to seventeen or eighteen inches in length. The body is smooth, fusiform, and elastic, and marked by numerous fine transverse rings. It is attenuated towards either extremity, the anterior end terminating in a prominently three-lobed mouth The tail is bluntly pointed. The female is much shorter than the male, having a diameter of nearly a quarter of an inch. The male is supplied with a double spiculum, its tail being always more or less curved towards the central surface. The female reproductive orifice is situated above the centre of the body. According to Schneider, the tail supports from 138 to 150 caudal papillæ, that is, from 69 to 75 on either side of the median line. Below the anus the papillæ are regularly arranged in pairs, seven in number, the two uppermost pairs being double.

Notwithstanding the advantage which the size of this entozoon affords us in the matter of observation and experiment, we are yet ignorant as to the precise mode in which the young gain access to the human body. From what has been said respecting the quick growth of _Ascaris mystax_ in the dog, and from what has been observed respecting the rapid growth of the so-called _A. suilla_ in the hog, we know that the worm requires but a short time to pass from the larval to the sexual state. The view of Hering, Mosler, Davaine, and others, who suppose that these worms are reared in a direct manner by swallowing the ova, is, as Leuckart observed, not yet proved. We are not in full possession of the facts of larval development. It is true that Professor Heller’s interesting “find” has shown that when these worms first gain access to the human body their size is quite insignificant. At the post mortem of an imbecile, Heller discovered eighteen young worms, varying in size from about 1/9″ to 1/2″ in length (2·75 to 13 mm.). The sexes were indistinguishable. As a set-off against this, Leuckart’s repeated attempts to rear _Ascaris lumbricoides_ and _A. mystax_ by means of direct feeding-experiments with the eggs all failed. Thus, we are yet left in doubt as to the destiny of the larvæ during the period which elapses between the time of their escape from the egg and the time of their entry into the human body. So important is the question as to the mode of origination, growth, and subsequent development of the larvæ, that it may be well to trace, however briefly, what steps have been taken to clear up the matter. Leuckart obtained his negative results by the administration of ripe ova to dogs, rabbits, swine, and mice. The eggs of _Ascaris lumbricoides_ have been kept alive by Dr Davaine for a period of more than five years. I have myself watched the development of their contents in fresh water through all the stages of yolk segmentation up to the stage of an imperfectly-organised, coiled, intra-chorional embryo, and have kept them in the latter condition for a period of three months. According to Davaine (‘Comptes Rendus,’ 1858, p. 1217), the fully-developed embryo is cylindrical, its length being, 1/100th of an inch. The mouth is not furnished with the three characteristic papillæ of the genus, and the tail terminates suddenly in a point. Davaine administered some of his five-year-old embryos to rats, and had the satisfaction of finding a few of these eggs in the rodent’s fæces, with their embryos still living, but striving to emerge. He also gave eggs to a cow, and introduced others into the stomachs of dogs in small linen-covered flasks. As a general result it may be said that the embryos escaped from their shells. Those eggs, however, in which the yolk-segmentation had not arrived at the early embryonal stage remained unaffected. According to Heller, the embryo of _A. lumbricoides_ casts its first skin while still within the egg, and “a subsequent ecdysis probably completes its definitive form” (l. c., s. 615). So far back as 1853 Verloren reared coiled intra-chorional embryos in the eggs of _Ascaris marginata_ within a period of fifteen days in distilled water. I also reared the embryos of this species in fresh water, and kept them alive for a period of nearly a year and a half, at the expiration of which time, and during the warm weather, some few of them succeeded in making their escape. According to Davaine, the eggs of many nematode species will readily retain their vitality though long exposed to dryness, but their yolk-contents will not go on developing during this period of exposure. As regards _A. mystax_, however, Heller remarks that whilst “the eggs have a great power of resisting external influences, their development is not arrested in spirits of wine, chromic acid, or oil of turpentine” (l. c., s. 631). In the case of _Ascaris tetraptera_ of the mouse, embryonic formation goes on in spite of the absence of external moisture. Davaine has noticed the same thing in the oxyurides of rodents. Dryness does not even destroy the eggs of _A. lumbricoides_ and _Trichocephalus dispar_. It would seem, in short, that the eggs of nematodes which normally take up their residence in cats, dogs, and in the carnivora which reside in arid regions, will develop embryos in the egg without external moisture. As before remarked, Davaine thinks it is not necessary that these nematode embryos should pass through any intermediary bearer, and he believes that they are often directly transferred to the stomach of their “hosts” whilst adhering in the form of an impalpable dust to the coats of their bearers, whence they are detached by the animal’s frequent habit of licking the fur. Davaine’s view has received some support from the observations and experiments of Unterberger with the eggs of _Ascaris maculosa_. This observer administered eggs of the worm to doves (whose fæces were free of eggs), and seventeen days after found ova in the fæces.

With the eggs of the _Ascaris megalocephala_ of the horse I performed numerous experiments. I reared the embryos in simple fresh water, and found them during warm weather escaping before the expiration of five months. I also succeeded in rearing these larvæ in pond mud, noticing, at the same time, that after their escape from the shell they grew more or less rapidly up to a certain point, after which they ceased growing. The addition of horses’ dung to soft wet mud in one case, and of cows’ dung in another, neither appeared to advance nor retard the process of embryonal formation, so long as the embryos were enclosed in their shells. On the other hand, when I reared embryos in simple horse-dung purposely kept moist, they attained a higher degree of organisation than did those in wet mud or water. Having watched hundreds of these larvæ under varying conditions, I came to the conclusion that, after escape from the egg, their activity, growth, and strength was most marked when they occupied media which happened to be impure. Davaine experimented on cows, and Leuckart also experimented on horses, with the eggs of this worm without success. Leuckart also failed to rear the larvæ in intermediary hosts. Some eggs passed through the water-palmer unaltered.

These results, so far as they go, seem to be borne out by facts of a professional order. Thus, an instance has been brought under my notice where a considerable number of peasants and their children, dwelling in a parish in Yorkshire, were infested with this worm. There was, in short, a local endemic helminthiasis. Through the parish runs a stream which supplies the cottagers with all the water they employ for domestic purposes (washing, drinking, and so forth). Some of the peasants living by the side of the stream keep pigs, and the sewage from this source has been allowed to pass into the stream itself. Now, if Schneider’s determination as to the identity of the lumbricoid of man and the pig is correct (which I do not doubt), the explanation of the cause of the endemic becomes a very simple matter. But it does not explain all that we desire to know about the young worms. Either the freed embryos before they enter the human bearer accomplish further changes of form and growth in the sewage or impure water; or, what is far less probable, they pass into the bodies of intermediary hosts (such as insect-larvæ, Gammari, Entomostraca, &c.) to undergo the necessary changes. Practically, no doubt, it comes to the same thing in the end. Even if we suppose that the _Ascaris suilla_ and _A. lumbricoides_ are not identical species, still it is evident that any person discharging the eggs of lumbricoids in the vicinity of open waters becomes, by that fact, a source and centre of infection. To ensure an endemic it is probably only further necessary that the human inhabitants should employ the contaminated water for domestic purposes. But time and an increase of temperature must be allowed for the bringing about of those known and unknown larval changes that alike form the necessary antecedents of infection. In this connection I will only add, that if the present position of the question be such as I have here represented it to be, we see that Mosler was not far wrong when he suggested that “contamination of the drinking water with the eggs out of privies is to be blamed” as a source of infection. According to Heller, from whom I quote, Mosler actually demonstrated the presence of the eggs in water thus exposed. In like manner it becomes obvious that Davaine’s practical remark (although it was based on the assumption of a direct infection by the eggs), that filtration will probably be sufficient to prevent infection, loses nothing of its hygienic value.

The foregoing observations naturally lead one to the question of frequency and distribution. Davaine holds that the comparative infrequency of this parasite in Paris is due to the free use of the filter. In London, though not uncommon, the worm rarely occurs in great numbers in one bearer. Those cases in our hospitals, where considerable numbers have been present, have usually come up from suburban or country places. Heller states that these worms were found in 9·1 per cent. of post mortems conducted at Dresden, in 12 per cent. at Erlangen, and in 17 per cent. at Kiel. He quotes Huss as stating that no one is free from this worm in Finland. The prevalence of large round worms in warm countries generally is well known. Throughout India and the East they are extremely abundant, and the same may be said of the West Indies, Brazil, and the adjacent territories. Professor Dyce and others have remarked on the extreme prevalence of lumbrici in the Mauritius, but they are comparatively rare along the sea border. In all situations where there is an abundant fresh-water supply these parasites are particularly common, as in the lowlands of Holland and the lake districts of Sweden. The abundance of water is certainly not alone sufficient to explain the frequency of the parasite, seeing that the most important factor is that which rests upon the uncivilised habits of the rural population. What, therefore, it may be asked, can be the cause of immunity enjoyed by Icelanders in this respect? The answer is not apparent; nevertheless Krabbe and Finsen have testified to the fact that Iceland is the only country that is entirely free from _Ascaris lumbricoides_.

As remarked in my previous work the number of worms present in any human bearer is usually small, varying commonly from one to six or eight. Cases in which scores or hundreds have existed are comparatively rare. Küchenmeister mentions the case of one child who passed 103 examples, and of another child that harbored from 300 to 400 worms. Dr Gilli, of Turin, gives a case where 510 were passed by a child, and Cruveilhier estimated that over 1000 existed in an idiot girl, whose intestines he found crammed with them. A remarkable case has also been communicated to me by Dr Mackeith, of Sandhurst, Kent, who, by means of santonine, expelled from a little girl, five and a half years of age, 300 lumbrici; and I am likewise indebted to Dr Cooper Rose for notes of a case in which about thirty lumbrici were expelled, chiefly in consequence of the employment of this drug. The most interesting fact, however, in this case was that the child was only fifteen months old. In this case the symptoms were severe.

The proper habitat of the lumbricus is the upper and middle part of the small intestine. From this situation it often wanders into the stomach, and frequently gains access to the outer world, not only by the natural passages of the mouth, nostrils, and anus, but also, occasionally, in a more direct way, by perforating the intestinal and abdominal walls. Many cases are on record where lumbrici have passed into the abdominal cavity. In other instances they have lodged themselves within the abdominal viscera and pulmonary organs. When they find their way into the parietes of the abdomen and adjacent parts, they usually give rise to the formation of abscesses requiring surgical interference.

As regards the symptoms produced by lumbrici, these vary according to the situation they happen to occupy. The symptoms are also modified by age and temperament. In the stomach and intestines they give rise to colic and shooting pains about the abdomen, followed generally by dyspepsia, nasal itching, nausea, vomiting, and even diarrhœa. Occasionally death supervenes suddenly. A singular case of this kind (the particulars of which I only gathered from a local newspaper) occurred in a boy, thirteen years of age, at the County Gaol at Hertford, in 1873. From Dr Evans’s statement, made at the coroner’s inquest, the sole cause of death appeared to be due to pressure on the windpipe by a worm lodged in the gullet. Sometimes there is cerebral disturbance, attended with general restlessness and convulsive twitchings during sleep. Thus, Dr Woodman has recorded a serious case of convulsions arising from lumbricoid worms, in which, however, a cure was effected by expulsion of the worms. An anonymous writer in the ‘Medical Gazette’ records a case of epilepsy from this cause, whilst another writer in the same journal (1839) mentions an instance where two lumbrici and one tapeworm were associated in the production of similar phenomena. But a much more striking case is also given (anonymously) in the ‘Gazette’ for 1874 (p. 415), where a single lumbricus caused the bearer to be a lunatic for eight years. The victim suffered from cataleptic fits, which lasted for two or three weeks at a time. M. Petrequin, in his ‘Traité Pratique,’ records two cases of amaurosis in young girls produced by lumbrici. A fatal case is recorded by Petrenz, where 200 worms produced enteritis, and another fatal case is given by Roger from perforation (1848). Cases of perforation are also given by Young, by Blair (1861), by Mondière (1839), by Buchner (1851), by Sheppard (1861), and by Luschka (1854), the worms in this last-mentioned case occupying the cavity of the pleura. Cases of severe irritation affecting the genito-urinary organs are given by Dreyfus, Buckingham, and others; and one or two instances are reported where these worms have been discharged from several parts of the body (Neilson, 1833). I may add that the third fasciculus of a work illustrating the collection of morbid anatomy in the Army Medical Museum at Chatham gives a case of lumbrici occupying the biliary ducts and gall-bladder. I find, moreover, two additional cases of perforation of the small intestine, one of which appeared in the ‘London Medical Gazette’ (1827) and the other in the ‘Lancet’ (1836).

During the Franco-German war Dr Reginald Pierson, as he afterwards informed me, removed a lumbricus from an abscess formed in the abdominal parietes of a soldier. But amongst the most curious cases (illustrating the wandering habits of these parasites) are those severally described by Barwell (1857), Williams, Prichard, and the Messrs Stockbridge. In Barwell’s case an Ascaris was expelled from a child who had swallowed the brass “eye” of a lady’s dress. Through the circular loop of this eye, used as a toy, the Ascaris had partly thrust its body, and becoming thus strangulated, it probably perished before it was evacuated. In Prichard’s case (1859) one or two lumbrici had similarly trapped themselves in the eyes of buttons swallowed by the patient, and one worm, not contented with a single strangulation, had succeeded in passing its body through two buttons. In 1842 Mr T. G. Stockbridge gave a similar case, in which he, not inaptly, spoke of these “hooks and eyes” as constituting a new remedy or “worm-trap” for lumbricus, and singularly enough, a namesake (W. Stockbridge), in the succeeding year, also recorded a like instance of the “mechanical expulsion of worms” by metallic buttons. Again, a third correspondent in the ‘Boston Journal,’ under the initials A. M., spoke of an open-topped thimble as constituting another new “worm-trap,” whilst he gave a case of lumbrici penetrating “metallic suspensor buttons.” There is also the case reported by Williams, who, at a meeting of the Boston Society for Medical Improvement, exhibited “a lumbricus with a dress-hook attached” (1857). Lastly, another lumbricus, trapped in the same way, may be seen in the Museum of the Royal College of Surgeons at Edinburgh.

Owing to the presence of a peculiar irritating vapour which is given out by these lumbricoids, particularly when fresh, several observers have experienced curious symptoms. Thus, Miram on two occasions, when examining _A. megalocephala_, was attacked with sneezing, excessive secretion of tears, with swelling of the puncta lacrymalia, and Huber also experienced a troublesome itching of the hands and neck after examining specimens of _A. lumbricoides_. In like manner I have myself had watery suffusion of the eyes (when collecting the perivisceral fluid for Marcet’s analyses: see Bibliog.), and Bastian has given a detailed account of the serious effects which the poison produced upon him. In Bastian’s case even spirit specimens produced irritation. The attacks of catarrh and asthma were so persistent and severe that they lasted for six weeks at a time. So sensitive was Bastian to the lumbricoid-miasm that he could not even put on a coat that he had worn during his investigations without experiencing fresh attacks of sneezing and other catarrhal symptoms. The attacks became periodical, occurring between five and six in the morning, being accompanied by dyspnœa and a distressing spasmodic cough. Bastian, in short, was quite a martyr in the cause of nematode anatomy.

BIBLIOGRAPHY (No. 34).--_Abousson, L._, “On the Presence of Worms (lumbrici) in the Air-passages,” from ‘Arch. Gén. de Méd.,’ in ‘Med.-Chir. Rev.,’ 1836.--(Anonymous), _A. M._, “Another New Worm-trap--an open-topped Thimble in the Nostril (also notice of metallic suspender buttons penetrated by Lumbrici),” ‘Bost. Med. and Surg. Journ.,’ vol. xxvii, p. 121, 1842-43; see also T. G. and W. Stockbridge.--(Anon.), “Lumbrici expelled by Bismuth,” ‘Bost. M. and S. Journ.’ (from ‘Gaz. des Hôp.,’ ‘Journ. des Connaiss. Méd.,’ and ‘Boletin del Inst.-Med.-Valenc.’), 1859.--(Anon.), “Case of one Tapeworm and two Lumbrici causing Epilepsy,” from ‘Bull. du Midi’ and ‘Gaz. Méd.,’ 1839.--(Anon.), “Case of Perforation of the Ileum by Ascarides,” from ‘Hufl. and Ossan’s Journ.,’ in the ‘Lancet,’ 1836.--(Anon.), “Case of Lumbrici in the Biliary the Ducts and Gall-bladder,” note and fig. in third fasc., illust. the Coll. of Morb. Anat. in the Army Med. Mus. at Chatham, 1838.--(Anon.), “A Lumbricus causing Catalepsy, with Fits lasting two or three weeks; Cure by Vomiting,” ‘Lond. Med. Gaz.,’ 1847, p. 415.--_Archer, E._, “On a Case of _A. lumbricoides_ producing alarming symptoms,” ‘Lancet,’ 1857.--_Barwell_, “Case of Ascaris expelled by the swallowing of a foreign body,” ‘Lancet,’ 1857.--_Bastian, H. C._, “On the Anatomy and Physiology of the Nematoids, Parasitic and Free,” ‘Phil. Trans.,’ 1866, p. 545; for the account of his poison-symptoms, see _footnote_, p. 583.--_Batterbury, R. L._, “Jaundice due to the presence of Lumbrici,” ‘British Med. Journ.,’ Nov., 1878, p. 721.--_Bigelow, H._, “Worm in an Abscess,” ‘Bost. Med. and Surg. Journ.,’ vol. xxxiii, p. 486, 1836.--_Blatchley, C. C._, “Two Cases of _A. lumbricoides_, attended with Abscesses, followed by large purulent discharges, and Worms therein,” ‘New York Med. and Phys. Journ.,’ vol. i, new series, p. 209, 1829.--_Bonfils, E._, “Lesions and Path. Phenomena caused by Lumbrici in the Biliary Ducts,” from ‘Arch. Gén.,’ in ‘Brit. and For. Med.-Chir. Rev.,’ 1858, and in ‘Amer. Journ. of Med. Sci.,’ vol. xxxvii, 1859.--_Bradford, J. T._, “Singular Case of Worms (Lumbrici),” ‘Bost. Med. and Surg. Journ.,’ vol. xxviii, 1843.--_Brigham, A._, “Worms in the Bladder simulating ‘Stone,’” ‘Amer. Journ. Med. Sci.,’ 1837; ‘Med.-Chir. Rev.,’ 1837; ‘Quart. Journ. Calcutta Med. and Phys. Soc.,’ vol. ii, p. 132, 1838.--_Buchner_, “On the Perforation of the Intestinal Canal by Worms (with ref. to two cases),” from ‘Med. Zeitung,’ 1850, in ‘Med.-Chir. Rev.,’ 1851.--_Calderwood_, “Treatment,” ‘Brit. Med. Journ.,’ Jan. 30, 1875.--_Chapman, N._, “Case of 68 Ascarides causing Pulmonary Disease,” in his ‘Dis. of the Thoracic and Abd. Viscera,’ p. 263, and in ‘Med.-Chir. Rev.,’ 1845.--_Chiaje, Delle-_, in ‘Rend. dell’ Accad. di Napoli,’ 1846 (“Anat.,” p. 403).--_Church, J._, “On _A. lumbricoides_,” ‘Mem. Med. Soc. Lond.,’ vol. ii, 1789.--_Claparède_ (l. c., Bibl. No. 33, for development).--_Clark, P._, “Discharge of a Lumbricus through the Male Urethra,” ‘New York Journ. Med.,’ 1844, rep. in ‘Lancet,’ 1844, and in ‘Edin. M. and S. Journ.,’ vol. lxiv, 1845.--_Cloquet_, ‘Anat. des vers Intest.,’ 1824.--_Cobbold_, “On Sewage and Parasites, especially in relation to the Dispersion and Vitality of the Germs of Entozoa,” ‘Med. Times and Gaz.,’ Feb. 25, 1871, p. 215.--_Idem_, ‘Entoz.,’ p. 302-315.--_Idem_, ‘Worms,’ lect. xvi, p. 3.--_Idem_, art. “Ascaridæ,” in ‘Maunder’s Treasury,’ 1862.--_Colvan, J._, “Case in which Eleven Round Worms of the species _A. lumbricoides_ were removed by Anthelmintics,” ‘Dubl. Med. Press,’ vol. xxvi, p. 211, 1851.--_Cutler, J. H._, “Death by Worms (a large Lumbricus being found in the Wind-pipe),” ‘Bost. Med. and Surg. Journ.,’ vol. lxvi, p. 392, 1862.--_Czermak_, in ‘Sitz. d. k. Akad. d. Wissensch.,’ 1852 (“Anat.,” s. 755).--_Davaine_, in his ‘Traité,’ l. c., 2nd edit., syn. xcvii, and p. 122-235 (with details of forty-five cases); see also his memoir “On the Development and Propagation of the _Trichoceph. dispar_ and _A. lumbricoides_,” from ‘Comptes Rendus,’ in ‘Ann. Nat. Hist.,’ vol. ii, 3rd series, 1858; also in the ‘Journ. of Pract. Med. and Surg.,’ Eng. edit., vol. i, 1858, and in the ‘Veterinarian,’ vol. xxxii, p. 700, 1859, from ‘Proc. of Acad. des Sci.,’ in ‘Bost. M. and S. Journ.,’ vol. lix, p. 157, 1858-59.--_Idem_, art. “Entozoaires,” in ‘Dict. de Méd. et Chir. prat.’--_David, J. B._, “Cases of Perforation of the Intestines by Worms,” from ‘Gaz. Méd. de Paris,’ in ‘Dubl. Med. Press,’ 1840, p. 223.--_Diesing_, ‘Syst. Helm.,’ ii, p. 166; and in ‘Revis der Nemat.,’ l. c., s. 660.--_Douglas, J._, “Worms (Lumbrici) evacuated at an Ulcer of the Groin,” ‘Med. Ess. and Obs.,’ vol. i, 2nd edit. (vol. i, 5th edit., p. 179), p. 222, 1737.--_Dowler, B._, “Case of Worms in the Urinary Bladder,” from ‘New Orl. M. and S. Journ.,’ in ‘New York Journ. Med.,’ new series, vol. xiv, 1855.--_Dubini_, ‘Entozoografia umana’ (“Anat.,” p. 148).--_Dupuytren_, “Lumbricus passed by the Urethra,” from “Clin. Lect.,” in ‘Lond. Med. and Surg. Journ.,’ 1846, p. 14.--_Dyce, R._, “On Lumbrici and the Causes of their Prevalence in the Mauritius,” ‘Lond. Med. Gaz.,’ 1834.--_Evans, T._, “Lumbricus causing Death,” rep. of coroner’s inquest in the ‘Herts Advertiser and St Alban’s Times’ for Feb. 8, 1873.--_Gervais_ (and _Van Beneden_), ‘Zool. Med.,’ ii, p. 118.--_Gilli_, “Account of a Case in which 510 Worms (Lumbrici) were voided by a Child,” from ‘Giorn. d. Scienze Med. di Torino,’ in ‘Med.-Chir. Rev.,’ 1843.--_Goopta, G. D. D._, “On Suicide and Lumbrici,” ‘Ind. Med. Gaz.,’ July, 1874, and ‘Lond. Med. Rec.,’ Aug., 1874, p. 502.--_Heller, A._, “Darmschmarotzer,” in Von Ziemssen’s ‘Handb.,’ s. 612-631.--_Holland, G. C._, “A peculiar Case of Nervous Disease or Derangement of the Nervous System (associated with _A. lumbricoides_),” ‘Edin. M. and S. Journ.,’ vol. lxiii, 1845.--_Howall_, “Abscess of the Groin, with discharge of Lumbrici,” ‘Lond. Med. Gaz.,’ 1845, and ‘Edin. M. and S. Journ.,’ 1846, p. 241.--_Johnson, W. G._, “Case of forty Lumbrici in a Boy who died with Traumatic Tetanus,” “Rep. of South Mid. Br. of Brit. Med. Assoc.,” in ‘Brit. Med. Journ.,’ 1858.--_Kell_, “Perforation of the Intestines by a Worm,” ‘Lond. Med. Gaz.,’ 1828.--_Kilgour, T._, “Case in which Worms in the Nose, productive of alarming Symptoms, were removed by the Use of Tobacco,” ‘Med. Comment.,’ vol. viii, 1783.--_Kirkland_, “Case of Lumbricus in an Abscess of the Liver,” rep. in his book, entitled ‘An Enquiry,’ vol. ii, p. 186 (quoted by Richter and Davaine), London, 1786.--_Küchenmeister_, ‘Manual,’ Eng. edit., p. 410-427.--_Leidy, J._, ‘Proc. Acad. Phil.,’ 1856, p. 50.--_Lente, F. D._, “Lumbricus in the Stomach causing Dyspnœa,” in his “Rep. of Cases occurring in the New York Hosp.,” in ‘New York Journ. of Med.,’ vol. v, new series, p. 167, 1850.--_Lettsom_, “Case of Lumbricus evacuated from an Abdominal Abscess,” ‘Trans. Med. Soc. Lond.,’ and ‘Lond. Med. Repos.,’ 1817.--_Leuckart_, l. c., s. 152-258.--_Lieberkühn_, in ‘Miller’s Arch.’ (“Anat. of _A. suilla_”), 1855, s. 331.--_Luschka_, “Case of Lumbrici within the Pleura,” from ‘Virch. Arch.,’ in ‘Med.-Chir. Rev.,’ 1854.--_Lowne, B. T._, “The Anatomy of the Round Worm,” ‘Trans. Roy. Micr. Soc.,’ 1871, p. 55.--_Maesson_, “On a Worm found in the Bubo of a Woman 36 years of age;” see ‘Entozoa and Parasites, being a ref. to numerous papers;’ from “Valentin’s Repertorium,” in ‘Month. Journ. of Med. Sci.,’ vol. ii, p. 559, 1842; also in ‘Micr. Journ. and Struct. Rec.,’ p. 85, 1842.--_Marcet, W._, “Chemical Exam. of the Fluid from the Peritoneal Cavity of _A. megalocephala_,” ‘Proc. Roy. Soc.,’ 1862, No. 72, p. 69.--_Martin, D. T._, “Large number of Worms (140 examples of _A. lumbricoides_) discharged from a Child five years old,” rep. from the “Stethoscope,” in ‘Bost. Med. and Surg. Journ.,’ vol. xliv, p. 301, 1851.--_Mattei, R._, “On a Case of two Lumbricoid Worms, which had penetrated during life into the liver, and were demonstrated by Prof. G. Pelizzari to his pupils in the Sch. of Path. Anat. of Florence,” from ‘Gaz. Med. Ital. Toscana,’ in ‘Dubl. Quart. Journ.,’ vol. xxiv, 1857.--_Michel_, “Case of Epilepsy in a Girl ten years of age, caused by Lumbrici,” from ‘Journ. des Connaiss. Méd.,’ in ‘Amer. Journ. of Med. Sci.,’ vol. vi, p. 451, 1843.--_M’Laggan, J._, “Gangrenous Sore from a large Worm in the Parietes of the Abdomen,” ‘Med. Comment.,’ vol. ii, 1774, p. 80.--_Molin_, in ‘Sitzungsb. d. k. Akad.,’ 1859, s. 23.--_Mondière_, “On Perforation by Worms (three cases),” from ‘L’Expérience,’ in ‘Med.-Chir. Rev.,’ 1839.--_Moore, E. D._, “Example of _A. lumbr._ ejected by the Mouth,” ‘Prov. Med. and Surg. Journ.,’ 1852.--_Morgan, J._, “Case of Perforation of the Stomach, probably by a (Lumbricus) Worm,” ‘Lancet,’ 1836.--_Morland, W. W._, “Ejection of numerous Lumbrici from the Mouth, impaction of the small intestine with Lumbrici, (of which 365 were removed post mortem),” ‘Bost. M. and S. Journ.,’ vol. lvi, 1857.--_Idem_., an “_A. lumbr._ of unusual size (over 17 inches long),” ‘Rep. of Bost. Soc. for Improv.,’ in ‘Bost. M. and S. Journ.,’ vol. lviii, p. 62, 1858.--_Neilson_, “Discharge of Worms from various parts of the Body,” ‘Med.-Chir. Rev.,’ and ‘Lond. Med. Gaz.,’ 1833.--_Omond, R._, “Case of Lumbricus attended with Hæmoptysis,” ‘Edin. Med. Journ.,’ 1856.--_Owen, R._, art. “Entozoa,” l. c.--_Padley, G._, “Jaundice and Lumbrici,” ‘British Med. Journ.,’ Dec. 14, 1878, p. 877.--_Petrenz_, “Case of fatal Enteritis produced by (200) Lumbrici,” from ‘Clarus and Radius’ Beitr. zur Pract. Heilk.,’ in ‘Dubl. Journ.,’ vol. xi, 1837; also in ‘Lond. Med. Gaz.,’ 1837.--_Playfair_, “Case of Lumbricus (69 specimens) cured by the Mudar,” ‘Calc. Med. and Phys. Soc. Trans.,’ vol. ii, p. 407, 1826.--_Pomeroy, C. G._, “Escape of Worms (17 Lumbrici) from the Navel of a Child,” ‘Bost. M. and S. Journ.,’ vol. xxi, 1840.--_Prichard, A._, “Case of Lumbricus,” ‘Rep. of East York and North Lincoln Br. of Brit. Med. Assoc.,’ in ‘Brit. Med. Journ.,’ 1859.--_Royer_, “Case of Intestinal Perforation by a Lumbricus,” report in ‘Lancet,’ 1856.--_Rumsey, N._, “Cases of Lumbricus and Tænia associated with Hæmoptysis,” ‘Med.-Chir. Trans.,’ 1818.--_Sandwith, H._, “Remarks on Worms in the Peritoneal Cavity, with a case,” ‘Brit. Med. Journ.,’ 1861.--_Schleifer_, “Case of a Deaf and Dumb Child restored after the discharge of Worms (87 Lumbrici and innumerable Oxyurides),” from ‘Œsterr. Med. Wochensch.,’ in ‘Amer. Journ. of Med. Sci.,’ vol. viii, p. 473, 1844.--_Schneider, A._, ‘Monog. der Nemat.,’ s. 36.--_Idem_, “On the Nervous System of Nematoda,” from the German by _Busk_, ‘Quart. Journ. Micr. Sci.,’ 1863.--_Schultze_, “Case of Stuttering occasioned by Worms,” from ‘Med. Zeit.,’ in ‘Med.-Chir. Rev.,’ 1837.--_Sheppard_, “Case of _A. lumbr._ extracted from an Abdominal Abscess,” ‘Brit. Med. Journ.,’ 1861.--_Smith, J. N._, “Thirty-nine Specimens of _Ascaris lumbricoides_ in a Child,” ‘Bost. M. and S. Journ.,’ 1856.--_Spalding, P._, “Case of Worms (100 Lumbrici),” _ibid._, 1839.--_Stockbridge, T. G._, “Worm-trap (hooks and eyes), a New Remedy,” _ibid._, vol. xxvii, p. 73, 1842-43; see also Anon., A. M.--_Stockbridge, W._, “Mechanical Expulsion of Worms (by metallic buttons),” _ibid._, vol. xxviii, p. 419, 1843.--_Van Beneden_, ‘Animal Parasites,’ l. c., p. 95; see also _Gervais_.--_Villemin_, “Case of Death from Worms (about 18 specimens of _A. lumbr._),” from ‘L’Union Méd.,’ in the ‘Lancet,’ and rep. in ‘Dubl. Med. Press,’ vol. xxxv, p. 327, 1856.--_Weinland_, in his ‘Essay,’ l. c., p. 88, and in ‘Troschel’s Arch.,’ 1859, s. 283.--_Welsh, T._, “Curious Facts respecting (symptoms produced by) Worms (_A. lumbricoides_),” art. ix in the ‘Med. Papers communicated to the Massachus. Med. Soc.,’ vol. i, p. 87, 1790.--_Wendelboe_, “Case of discharge of Worms (Ascarides?) through the Skin,” from ‘Rep. of Roy. Soc. Copenhagen,’ in ‘Lancet,’ 1836; see also _Neilson_.--_Williams, H. W._, “Exhibition of a Lumbricus with a dress-hook attached,” ‘Rep. of Bost. Soc. for Med. Improv.,’ in ‘Bost. M. and S. Journ.,’ vol. lvi, p. 163, 1857.--_Wilson, J._, “On the prevalence of Lumbrici in China,” in his ‘Med. Notes on China,’ London, 1846.--_Woodman, W. B._, “Case of Convulsions, &c., arising from Lumbricoid Worms,” ‘Med. Times and Gaz.,’ 1863.--_Young, W._, “Cases in which Lumbrici were evacuated by Ulceration through the Parietes of the Abdomen,” ‘Lond. Med. Gaz.,’ from ‘Glasgow Med. Journ.,’ 1828; rep. in ‘Lond. Med. and Surg. Journ.,’ vol. i, p. 564, 1828.

SECTION IV.--PART I.--ACANTHOCEPHALA (Thornheaded worms).

_Echinorhynchus gigas_, Goeze.--There is but one recorded instance of the occurrence of this entozoon in the human body. This is the oft-quoted case by Lambl, given in the ‘Prager Vierteljahrschrift’ for 1859. Lambl, indeed, described it as a separate species (_E. hominis_), but as the worm was a sexually-immature female, its identification with _E. gigas_, notwithstanding Schneider’s great authority, can hardly be regarded as absolutely certain. The worm was found in the small intestine of a boy of nine years, and measured only rather more than the fifth of an inch in length. As Leuckart hints, the worm may be _Echinorhynchus angustatus_, or possibly the _E. spirula_, a species found in various South American apes (_Cebus_ and _Jacchus_), and also in the Barbary ape (_Inuus_).

In 1872, Welch, unaware of Lambl’s case, announced the discovery of “the presence of an encysted Echinorhynchus in man.” The minute parasite found by him occurred in a soldier, thirty-four years of age, who died at Netley, but who had contracted the worm in India. “It was situated in the jejunum, immediately beneath the mucous coat, and formed an oval prominence in the interior of the gut.” Speaking with great confidence, this able microscopist further remarks:--“The character and arrangement of the hooklets unequivocally shadowed forth a species of Echinorhynchus for the first time discovered as a representative of the Acanthocephala in the human body.” Along with his elaborate description Welch gives several figures; but these, so far from producing conviction as to the accuracy of his inferences, have unfortunately led me to believe that the parasite in question would be more properly referred to the _Pentastomidæ_. But for Heller’s acquiescence I might have more fittingly noticed this worm elsewhere. Davaine falls into the same view, and moreover accepts Lewis’s “Echinorhynque du Chien,” which I have shown to be a nematode (_Cheiracanthus robustus_). It is thus that serious errors creep into the literature of parasitism.

In the adult state the female _Echinorhynchus gigas_ is a huge species, occasionally reaching two feet in length, with a breadth of one third of an inch. The male rarely exceeds three inches. This worm is common in swine, both wild and domesticated. According to Schneider the embryos take up their residence in the grubs or larvæ of the cockchafer (_Melolontha vulgaris_), a discovery which very readily explains the manner in which hogs become infested. Whether _E. gigas_ be a human parasite or not, it is certainly very injurious, not to say destructive, to swine. Although this parasite must be quite common in England I have experienced great difficulty in procuring specimens. In the second book of this work I shall give some interesting particulars furnished by the memoir of Prof. Verrill and privately by Mr George Wilkins. (See ‘Parasites of the Pachydermata’.)

BIBLIOGRAPHY (No. 35).--_Blanchard_, in ‘Cuvier’s Règne Animal,’ tab. 35 (good fig.), and in ‘Ann. d. Sci. Nat.,’ ser. xii.--_Bremser_, ‘Icones,’ tab. vi.--_Cobbold_, “Parasites of the Hog,” the ‘Veterinarian,’ 1875.--_Idem_, ‘Manual,’ l. c., p. 123.--_Davaine_, l. c., ‘Syn.,’ p. 83.--_Diesing_, l. c., ii, p. 2.--_Dujardin_, l. c., p. 503.--_Goeze_, l. c., s. 143 (good figs.).--_Gurlt_, l. c., s. 367.--_Heller_, ‘Darmschmarotzer,’ l. c., s. 663.--_Lambl_, l. c., _supra_, Feb., 1859.--_Leuckart_, l. c., Bd. ii, s. 729; also in ‘Bibl. Univ.’ for March, 1863, and in ‘Ann. Nat. Hist.,’ vol. xii, 1863.--_Owen_, l. c., in ‘Todd’s Cyclop.’ (figs. after Cloquet).--_Rudolphi_, ‘Synops.,’ pp. 63 and 310.--_Schneider_, in ‘Arch. f. Anat. und Phys.,’ 1868.--_Idem_, in ‘Sitzungsb. der Oberhess. Gesellsch. f. Nat.,’ &c., 1874 (quoted by Leuckart); see also ‘Ann. Nat. Hist.,’ 4th series, vol. vii, p. 441, 1871.--_Verrill_, ‘The external and internal Parasites,’ &c., l. c., p. 109.--_Welch_, “The presence of an Encysted Echinorhynchus in Man,” ‘Lancet,’ Nov. 16, p. 703, 1872.--_Westrumb_, ‘De Helm. Acanth.’ (good figs.), 1821.

SECTION IV.--PART II.--SUCTORIA (Leeches)

As explained in the Introduction we must regard the Leeches and many allied forms of Suctorial Annelids as creatures possessed of semi-parasitic habits. They are, perhaps, something more than what Van Beneden styles “free parasites”--an expression which almost looks like a contradiction of terms. I cannot here, however, stop to discuss questions which lie, as it were, on the border-land of parasitology. Three species of leech are more or less commonly employed in medicine. These are the grey leech (_Sanguisuga medicinalis_, Savigny), the green-leech (_S. officinalis_, Sav.), and the dragon-leech (_S. interrupta_, Moq.-Tandon). The two former abound in Central and Southern Europe, being also present in North Africa, the last named inhabiting Barbary and Algeria. So abundant are leeches in the country bordering the Mediterranean that during the invasion of Egypt by Napoleon the French soldiers suffered seriously from their attacks. When the men lay down to drink, the leeches (_Hæmopis sanguisorba_, Sav.) affixed themselves to their mouths and nostrils, producing serious distress. They also attacked horses, camels, and cattle. In like manner the Ceylon and Philippine Island leeches (_S. ceylonica_, Moq.-Tand., or _S. tagalla_, Meyen), of which there are several varieties, prove exceedingly troublesome to Europeans. These leeches, not being aquatic forms, occupy woods and damp places. Unless the limbs of travellers are well protected, the presence of the blood-suckers is soon discovered by the trickling of blood from the limbs and lower part of the body. The leeches even sometimes creep up to the neck and other adjacent parts. These “free parasites” also attack horses, causing much loss of blood. Terrestrial leeches abound more or less in all warm countries. Sir J. Hooker encountered them in the Himalayas, and they are common in China, Japan, Java (_S. Javonica_, Wahlberg), and other eastern parts. They likewise abound in Brazil and Chili. The American leeches for the most part belong to the genus Hæmenteria (_H. Mexicana_, _H. officinalis_, and _H. Ghiliani_, Filippi). The last named is common in Brazil, the other two being Mexican forms. Another species, which is blind, has been found in Brazil by F. Müller (_Cyclobdella lumbricoides_). Not only the above-named species, but also many other kinds of leeches are in the habit of attacking man and the domestic animals, but the subject is too extended and special to be fully dealt with in this work. Almost a legion of species are known as externally parasitic upon Fishes, Chelonian and Batrachian reptiles, Crustaceans, and Echinoderms.

BIBLIOGRAPHY (No. 36).--_Blainville_, ‘Dict. des Sci. Nat.,’ tom. xlvii, p. 257.--_Brandt_ (und _Ratzeburg_), ‘Medicin. Zoologie,’ Bd. ii.--_Brightwell_, ‘Ann. and Mag. Nat. Hist.,’ ix, 1842.--_Diesing_, ‘Syst.,’ vol. i, p. 465, and “Revis. der Myzelminth. (Abth. Bdellideen),” in ‘Sitzungsb. der math.-nat. Cl. d. k. Akad. der Wissensch.,’ Bd. xxxiii, s. 473.--_Ebrard_, ‘Compt. Rend.,’ 1856, p. 1012.--_Idem_, ‘Monogr. des sangues Méd.,’ 1857.--_Filippi, De_, ‘Mem. Accad., &c., Torino,’ and in ‘S. und K. Zeitsch.,’ 1829.--_Idem_, “Nuovo genere,” &c., in ‘Gaz. Med. Lombard,’ 1849.--_Grube_, ‘Fam. d. Annelid.,’ s. 109.--_Hofmeister_, in ‘Burmeister’s Zeitung für Zool.,’ 1848.--_Johnson_, ‘Treatise on the Medicinal Leech.’--_Leuckart_, l. c., Bd. ii, s. 634-739 (with many refs.)--_Leydig_ (“Anat.”), ‘S. und K. Zeitsch.,’ Bd. i.--_Moquin-Tandon_, ‘Monogr. de la fam. des Hirudinées,’ 1846.--_Idem_, in his ‘Medical Zoology’ (Hulme’s edit.), 1861, p. 137.--_Müller, F._, in ‘Archiv f. Naturg.,’ 1846.--_Pereira_, in his ‘Materia Med.,’ vol. ii, p. 2197, 1853.--_Savigny_, ‘Descript. de l’Egypte,’ 2nd edit.--_Idem_, ‘Syst. des Annélides,’ 1820.--_Schmarda_, ‘Neue wirbell. Thiere,’ Bd. i (quoted by Leuckart).--_Virey_ (and _Serullas_), in ‘Journ. Pharm.,’ 1829, p. 614.--_Wagener_, in ‘Troschel’s Archiv,’ 1858, Bd. i, s. 244 _et seq._--_Wahlberg_, in ‘Œfvers. Kongl. Vetensk. Akad. Forhand.,’ Stockholm, 1855.

SECTION IV.--PART III.--ARACHNIDA (Pentastomes, Mites, Ticks).

The Trachearian division of the Arachnida comprises a few internal parasites that attack man, and many ectozoa which are parasitic upon man and animals. The species can only be noticed very briefly.

_Pentastoma tænioides_, Rudolphi.--In the system of classification adopted by Diesing, this entozoon and its allies are placed in the division _Cephalocotyleen_ and therefore, in association with the Cestodes, with which, however, it has no structural affinity. It was long ago pointed out by Van Beneden, T. D. Schubart, Leuckart, and others, that the pentastomes were Acarine and Lernæan Arthropods; the genus being osculant between the Acaridæ and Lernæidæ. The whole subject is discussed in Leuckart’s profound memoir quoted below.

The adult _Pentastoma tænioides_ is characterised by the possession of a vermiform, lancet-shaped body, flattened at the ventral surface, attenuated posteriorly, and marked transversely by about ninety rings (fig. 50, 1 and 2). The cephalo-thoracic segments are continuous with the body, each supporting a pair of strong retractile chitinous claws; four in all. The head is truncated, furnished with an oval mouth, armed with a horny lip. The integument of the body is perforated with numerous respiratory openings or stigmata. These are wanting in the cephalic segment. In the larval state (══ _Pent. denticulatum_) the body is armed with numerous rows of small, sharply pointed spines. The adult female measures from three to four inches in length, but the male is only about an inch long. The genital aperture of the female is situated at the extremity of the tail, that of the male being placed at the front part of the abdomen in the middle line. The mode of reproduction is oviparous, accompanied by a subsequent and complete metamorphosis.

In the mature condition this parasite infests the nostrils, and frontal sinuses of the dog and wolf, and also, though more rarely, the nasal cavities of the horse and sheep. In the pupal and larval states it sometimes occurs in the abdominal and thoracic cavities of the human body, but it is more frequently found in herbivorous mammals, such as the sheep, deer, antelope, peccary, porcupine, guinea-pig, hare, and rat. According to Creplin, it infests the domestic cat. In these animals and in man the young worms occupy little cysts within or upon the peripheral parts of the liver and lungs. I have occasionally found them free in the cavities of the abdomen and pleura.

In the course of the development of this entozoon, Leuckart recognises four well-marked stages. The _first_ is that of the embryo with a boring apparatus. In the _second_ stage, the embryo has become transformed into a motionless pupa. The _third_ is the ordinary larval condition characterised by numerous rows of small spines in addition to two pairs of double claws. The _fourth_ is the sexually-developed stage, furnished with a simple hook-apparatus, and without integumentary denticles. “Our Pentastomes, therefore,” says Leuckart, “exhibit two kinds of larval forms, an earlier and later one, such as takes place in other animals; this also occurs even in insects (_Strepsiptera_ and _Meloidæ_), only that, in our case (_i. e._ in _Pentastoma_), both do not immediately follow one another, but are separated by a resting condition, which I have designated as the pupa stage. In choosing this name I do not mean to express a complete identity of this intermediate state with the pupal sleep of insects.”

So far as my own observations extend, the pupa, in its later stages, closely resembles the free larva; but, as Leuckart points out, the earlier stages are very different. The embryo, after encystation, repeatedly casts its skin, and during the intervals of these several successive moultings, the young animal makes rapid growth, accompanied by a series of structural changes. Passing through these it at length acquires the perfected larval state (_P. denticulatum_).

As regards the occurrence of this entozoon in the human body, the best account is that given by Frerichs. As quoted in my previous work from Murchison’s edition of Frerichs’ well-known clinical treatise, the German _savant_ remarks:--“The Pentastoma is a parasite which has only recently been discovered in the human subject, but it is, nevertheless, far more common in the human liver than the echinococcus. It is devoid of clinical importance, because it does not give rise to any functional derangements. Pruner (‘Krankheit des Orients,’ 1847, s. 245) was the first who pointed out the existence of the Pentastoma in the human liver. On two occasions he found an encysted parasite in the liver of negroes at Cairo, the nature of which, however, he did not accurately determine. Bilharz and Von Siebold (‘Zeitschr. für Wissench. Zoologie,’ Bd. iv, s. 63) recognised in it a new variety of Pentastoma, to which he gave the name of _P. constrictum_. In Germany the Pentastoma was found in the human liver by Zenker (‘Zeitschr. f. ration. Med.,’ 1854, Bd. v, s. 224); it occurs, however, not only in this gland, but also in the kidneys, and in the submucous tissue of the small intestine (Wagner). The parasite is by no means rare with us. Zenker, at Dresden, succeeded in finding it nine times out of 168 autopsies; Heschl, at Vienna, met with it five times out of twenty autopsies; Wagner, at Leipsig, once in ten. According to Virchow, it is more common in Berlin than in Central Germany. During six months at Breslau I met with it in five out of forty-seven dead bodies. The Pentastoma-endemic in Germany is not identical with that which occurs in Egypt; the former is the _P. denticulatum_ of Rudolphi.” This clear statement of Frerichs is valuable; but, as Murchison has also pointed out, there is some discrepancy between Frerichs and Küchenmeister’s record of Zenker’s experience. According to Küchenmeister, Zenker met with the Pentastoma thirty times in 200 autopsies.

Although from a purely clinical point of view, and speaking generally, this worm, as Frerichs says, can claim little attention, yet, as we shall see (when treating of the parasites of the dog), it occasionally proves fatal to the canine bearer. Not only so, it may even occasion severe inconvenience to the human bearer. Quite recently a remarkable instance of this kind occurred in Germany, some notice of which appeared in the ‘Medical Times and Gazette,’ Jan. 4th, 1879, as follows:

“Dr Landon of Elbing (‘Berl. Klin. Wochenschrift,’ No. 49, 1878) relates the case of a workman, aged forty-two, who soon after the Franco-German campaign of 1870 was laid up with pain in the hepatic region, jaundice, and gastric disturbance, which symptoms persisted more or less until 1874, when he came under Dr Landon’s care with an attack apparently of perihepatitis. It then appeared that since 1871 he had also suffered from severe attacks of epistaxis, which occurred often twice in the same day. The patient complained of a feeling of painful pressure in the left nasal cavity, but with the speculum nothing but a moderate degree of inflammatory swelling could be detected. Suddenly, at Easter, 1878, a parasite was dislodged from the left side of the nose by a violent sneeze, and from that moment the epistaxis has not occurred. Its cause proved to be the _Pentastoma tænioides_.”

As the full-grown parasite occupies the nasal chambers of the dog, it is clear that the act of sneezing will be liable to transport the eggs and their contained embryos to the face and other exposed parts of persons who fondle dogs. In this way the germs will readily gain access to the human mouth. Ordinarily, the germs are introduced into the human stomach with uncooked vegetable food and fruits, to which they adhere after expulsion from the animal’s nostrils. The slimy nasal mucus secures this attachment, especially when it has become dry by exposure to the air. On reaching the stomach the embryos escape the egg-coverings and bore their way directly to the liver and other viscera, in which organs they become encysted and undergo the pupal transformation. Eventually they acquire a length of 2 to 2-1/2 lines (_P. denticulatum_). After a while the capsules enclosing the larvæ undergo calcareous degeneration, the parasite perishing.

In the case of dogs it is easy to perceive that when the animals are engaged in devouring the flesh of herbivora, the liberated larvæ will often come in contact with their noses. In this way contraction of the body, aided by the integumentary denticles, will secure their entrance into the nasal cavities. For our own security, therefore, we should avoid contact with dogs which frequent butchers’ shops and knackeries, and be sure that our market-garden fruits and vegetables are carefully washed before they are brought to table.

_Pentastoma constrictum_, Von Siebold.--This parasite is at present only known to us in the immature condition; unless, indeed, as is by no means improbable, the adult worm has been described under some other name. It was first discovered by Pruner on two occasions in negroes, and he also subsequently found two specimens of the worm preserved in the Pathological Museum at Bologna, which had been removed from the human liver. Pruner also found it in the giraffe. Bilharz afterwards frequently detected it in the livers of negroes at Cairo. It differs from the larval form of _P. tænioides_ in not possessing integumentary spines; moreover, it is a much larger parasite. The cephalothorax is furnished with four foot-claws, and the elongated abdomen displays twenty-three rings placed at tolerably regular intervals. The anterior part of the animal is obtusely rounded off, the caudal end being conical. The worm usually attains a length of rather more than half an inch, whilst the breadth scarcely exceeds a line.

An extremely interesting account of this worm has been published by Prof. Aitken, accompanied with illustrations by Dr H. C. Gillespie, taken from specimens in the Pathological Museum at Netley. Two cases are recorded. In one of these the encysted worms were found in the liver and lungs, and in the other in the liver only. In Dr Crawford’s account of the post mortem in the last-mentioned case, Prof. Aitken quotes him as saying: “These worms varied in length from an inch to an inch and a half, and were found coiled up like a watch-spring, in small sacs scattered throughout the whole organ.” The patient was a private of the 1st West India Regiment, and died at Bathurst, Gambia, in 1854. In the other case, where the lungs and liver were infested, the patient was an African, about twenty-one years old, who had enlisted into the 5th West India Regiment at Up Park Camp, Jamaica. He had, a few months previously, come from the slave depôt at Rupert’s Valley, St Helena. According to the post-mortem report, furnished by Mr Kearney (staff surgeon), the lower lobe of the right lung contained one or two yellow specks. “When cut into, worms were seen regularly encysted in its substance.” The surface of the liver was dotted over “with about twenty or thirty yellow specks, similar to those seen in the lung.” The longest of these specimens was a trifle less than three quarters of an inch.

Whether _Pent. denticulatum_ be or be not devoid of clinical interest, it is quite clear from Aitken’s account that _P. constrictum_ is a formidable parasite and one that occasionally proves fatal to the bearer. As his remarks suggest, a parasite that can produce both pneumonia and peritonitis is not a creature that either the physician or the sanitarian can afford to ignore. Lastly, I must again express my belief that the so-called _Echinorhynchus_, described by Welch, if it be not the _Pentastoma denticulatum_, must either be referred to _P. constrictum_ (in an early larval condition), or to some other hitherto undescribed pentastomatoid larva.

BIBLIOGRAPHY (No. 37).--_Aitken, W._, “On the occurrence of _Pentastoma constrictum_ in the Human Body as a cause of painful Disease and Death,” repr. from the ‘Science and Practice of Medicine,’ 4th edit., 1865.--_Bellingham_, in ‘Ann. Nat. Hist.,’ vol. xiv, p. 162.--_Blanchard_, in ‘Ann. des Sci. Nat.,’ ser. 3, t. viii, and in ‘Règn. Anim.’ (with figs.).--_Cobbold_, ‘Entoz.,’ p. 393 _et seq._--_Idem_, in ‘Quart. Journ. Med. Sci.,’ 1859, p. 205.--_Idem_ (“_P. cephalophi_”), in ‘Linn. Trans.,’ xxii, p. 357, and xxiii, p. 350.--_Idem_, in ‘Zool. Soc. Proc.,’ 1861, p. 124.--_Diesing_, ‘Syst.,’ i, p. 609.--Idem, ‘Revis. der Cephalocot.,’ s. 327.--_Frerichs_ (l. c., in text), vol. ii, p. 276.--_Klob_ (und _Schroff_), in ‘Gesellsch. d. Aerzte,’ Wien, 1860.--_Küchenmeister_, l. c., i, s. 370, Eng. edit., tab. viii.--_Idem_ (with _Van Beneden_), in ‘Bullet. Acad. Belg.,’ xxii (with figs.), 1855.--_Landon_ (quoted in text).--_Leuckart_, in ‘Zeitsch. f. rat. Med.,’ 1857; see also “Obs. on the development and early condition of the _Pent. tænioides_,” in ‘Ann. Nat. Hist.,’ vol. iii, 3rd series, 1859; also my translation of his “Further Observations on the development of _P. tænioides_,” from ‘Henle and Pfeufer’s Zeitsch.,’ in the ‘Quart. Journ. of Micr. Sci.’ for 1859.--_Idem_, ‘Bau und Entwicklungsgeschichte der Pentastomen, nach Untersuchungen besonders von _P. tænioides_ und _P. denticulatum_,’ Leipzig, 1860.--_Moquin-Tandon_, ‘Med. Zool.’ (Hulme’s edit.), “The Linguatula,” p. 329.--_Pruner_ (“Nematoideum”) in ‘Krankh. d. Orient.,’ 1847.--_Schubart_, ‘S. und K. Zeitschr.,’ Bd. iv.--_Welch_, see Bibl. No. 36.--_Zenker_, in ‘H. und Pf. Zeitschr. f. rat. Med.,’ 1854, s. 212 (with figs.).

The ectoparasitic arachnidans comprise a great variety of mites and ticks (_Acaridæ_ and _Ixodidæ_) more or less proper to man, and also a number of creatures which, though hardly to be reckoned as human parasites, are apt to transfer themselves from animals to man. Little more than an enumeration of the forms is possible here. The Common Scab or Itch insect (_Sarcoptes scabiei_) forms the type of a great variety of arachnids, generally spoken of as different species according to the host they dwell upon. Mégnin, however, in his beautiful memoir, quoted below, regards most of the forms of this genus (found on the horse, hog, sheep, dog, wolf, and other animals) as mere varieties. In man the female Acarus burrows beneath the skin, forming galleries or curved channels, in which she deposits her eggs. The irritation produced is not alone due to these excavations, but to the presence also of a poison which the mite discharges when feeding. The _Sarcoptes crustosæ_ of Fürstenberg, producing the Norway itch, is a variety, if, indeed, it can be called as much. Under the frightful name of _Dermatophagoides Schérémétewsky_ two parasites found on an herpetic patient have been described as new to science by M. Bogdanoff, but Mégnin points out that these Acari are only female and young male representatives of his _Chorioptes setiferus_ (var. _bovis_) respectively. In Newfoundland, Dr Le Roy de Méricourt discovered a singular species upon an officer who had come from Havannah (_Tyroglyphus Méricourti_, Laboulbène). It possesses enormous palpi, as in the genus _Chyletus_ to which Robin refers it. Another ectozoon, placed by Mégnin and others amongst the lowest types of Arachnida, is the well-known _Demodex folliculorum_. It is a gregarious species, a dozen or more examples often being present in a single dilated hair follicle. Though disfiguring to the human face it produces little harm. M. Gruby made it out to be a very common parasite, infesting forty out of sixty persons; but Mégnin, in his brochure (l. c. infra, p. 119), shows this statement to be an exaggeration. It infests on the average not more than one in ten persons. According to Gruby, moreover, a single follicle in the dog may contain 200 of these mites, another statement which Mégnin deems unreliable. The _Demodex_ of the dog is only a variety (fig. 53). Many other human Arachnids have been found, some of which appear to be genuine species, whilst others are accidental, so to speak. Of the former kind, perhaps we may reckon the two species discovered by Hessling (_Cœlognathus morsitans_ and _Entarsus cancriformis_). Of the latter sort, those found by Busk, Simon, and Bory de St Vincent may be cited. The mite found in Simon’s case was the _Dermanyssus avium_, which infests cage-birds. Probably it was the same species which Bory found on a lady; but in Busk’s negro sailor the mite may have been _D. gallinæ_ of the common fowl. Differing from the mites, proper, and also from the true ticks, are some bug-like forms called Argades. The two best known are the Miana bug of Persia (_Argas persicus_) and the Chinche of Columbia (_A. chinche_). Like their congener infesting pigeons (_A. reflexus_) these parasites are terrible blood-suckers. The bite of the Persian bug is so venomous as to have occasioned death. Various species of tick have been known to attack man, but the species have not been well determined. Although a human form has been described (_Ixodes hominis_, Koch), yet it is more probable that the species usually attacking man are the same as those known to infest the domesticated animals. In this list we may, therefore, reckon _Ixodes nigra_, _Ix. bovis_, _Ix. ricinus_, and _Ix. reduvius_. Cases in which one or other of these ticks occasioned much pain and distress are recorded by Hussem, Raspail, and Dr Cosson. Besides these there is a formidable tick well known at Angola (_Ix. monbata_). Its habits are like those of the common bed-bug. Severe pain comes on two hours after the person is bitten. It likewise attacks animals. The _Ix. carapato_ is similarly troublesome in Brazil. Another very disgusting arachnid liable to attack man is the _Galeodes araneoides_. This large spider-like creature, two inches in length, commonly attacks camels and has an extremely venomous bite. One or more species of the dung-beetle mites (Gamasidæ) have also been known to fasten themselves on man. According to Latreille, they first get attached to the clothes of travellers, whence they pass to his body, and there shift about, producing great torment. Another disagreeable arachnid is the little harvest bug (_Leptus autumnalis_), which not only excites irritation during its crawling motion on the human skin, but even succeeds in burying itself near the hairs. The irritation thus produced is almost unbearable. This mite attacks various animals, especially dogs and cats. I myself once suffered severely from this species in consequence of fondling a young wild rabbit which, as I afterwards discovered, was much infested. When the parasites had reached my left arm-pit they occasioned extreme torture. I have known these autumnal spiders to produce small suppurating boils on the abdomen. I may add that Dr Tilbury Fox has brought under my notice an instance where the hexapod larva of another species (probably _Trombidium cinereum_) was found to have occasioned severe irritation in a child.

BIBLIOGRAPHY (No. 38).--_Alibert_, ‘Maladies de la Peau,’ Paris, 1833.--_Audouin, V._, art. “Arachnida,” in ‘Todd’s Cyclop.,’ vol. i, 1836.--_Beneden, Van_ (_et Gervais_), ‘Zool. Med.,’ 1859.--_Bourguignon_ (_et Delafond_), in ‘Rec. Vét.,’ 1856.--_Idem_, in ‘Mém. de l’Institut.,’ 1862.--_Cobbold_, “Case of _Leptus_ producing Boils,” in ‘Worms,’ p. 140, London, 1872.--_Gamgee_, ‘Our Domestic Animals in Health and Disease,’ Edin., 1861.--_Gerlach_, ‘Kraetze und Räude,’ 1857.--_Hebra_, in ‘Oester. Jahrb.,’ 1864.--_Hering_, ‘Die Kraetzmilben,’ Stuttgard, 1845.--_Krabbe_, “Husdyrenes paras. Mider.,” ‘Tidssk. f. Vet.,’ Rœk. 2, Bd. iii.--_Küchenmeister_, l. c., 1855, s. 412 (good figs.).--_Mégnin_, ‘Monographie de la tribu des Sarcoptides psoriques.’ (This work contains a full bibliography and numerous beautiful plates; see also Review in the ‘Veterinarian,’ Aug., 1877, p. 563).--_Idem_, “Mémoire sur un nouveau Symbiote (_Chorioptes_, Gerv.),” ‘Journ. de l’Anat. et de la Physiol.,’ 1872.--_Idem_, “Mém. sur un nouvel Acarien,” _ibid._, 1873.--_Idem_, “Mém. sur les Hypopes,” _ibid._, 1874.--_Idem_, “Mém. sur l’organisation et la distribution zoologique des Acariens de la famille des Gamasidés,” _ibid._, 1876.--_Idem_, “Mém. sur les métamorphoses des Acariens en général, et en particulier sur celles des Trombidions,” ‘Ann. des Sci. Nat.,’ 1876.--_Idem_, “Des conditions de la contagion de la gale des animaux à l’homme,” ‘Arch. générales de Méd.,’ 1876.--_Idem_, “Mém. sur le _Demodex folliculorum_ (Owen),” ‘Journ. de l’Anat. et de la Physiol.,’ 1877.--_Moquin-Tandon_, ‘Elém. de Zool. méd.’ (Hulme’s edit., p. 302-328), 1861.--_Williams_, in his ‘Veterinary Surgery’ (good figs., reproduced from Gamgee’s translation of ‘Gerlach,’ &c.), 1872.

SECTION IV.--PART IV.--CRUSTACEA (Gammaridæ).

Although multitudes of small Crustaceans are parasitic upon fishes, and some few of them adhere to oceanic mammals (Cetacea), I am sceptical as to the parasitism of Crustacea either in or upon man. Many of the Amphipodous Gammari lead a sort of free parasitic existence, and they are themselves very liable to harbor larval parasites. As regards human parasitism from this source the only records known to me are those quoted below.

BIBLIOGRAPHY (No. 39).--_Banon_, “Freshwater Shrimp, or _Gamarus pulex_ (said to have been passed per anum),” ‘Rep. of Path. Soc. of Dublin,’ in ‘Dub. Med. Press,’ April 6, p. 351, 1864.--_Bartels_, “_Gamarus pulex_ in the Human Subject, with a postscript by Troschel,” trans. by Dr E. P. Wright, from ‘Verhandl. des Naturhist. verein. der Preuss. Rheinl. und Westph.,’ in ‘Dubl. Med. Press,’ 2nd ser., vol. ix, p. 407, 1864.--_Wright, E. P._, ‘Remarks on Dr Banon’s Case’ (see Bartels).

SECTION IV.--PART V.--INSECTA (Coleoptera, Diptera, Hemiptera, Aphaniptera).

Whilst very many flies, bugs, lice, and fleas persecute animals, not a few of them also attack man. Several of the species are genuine parasites, others are semi-parasitic, and others, again, are altogether outside the border-land of parasitism in the ordinary sense of the term. In fact, it becomes difficult to say where the line of parasitism should be drawn. I cannot, however, ignore all notice of the insect tormentors, whether strictly parasitic or not.

At least fifty different species have been regarded as playing the rôle of parasitism in man. Amongst the Coleopterous parasites none is more authentic than _Blaps mortisaga_. At least half a dozen such cases have occurred. Mr Hope’s catalogue of insects producing parasitism in man gives three examples of _scolechiasis_ from this source. Sir J. R. Cormack published a fourth case, and I have recorded a fifth. In this instance I received the living larva from Dr Horne, of Barnsley, who procured it from an infant eleven weeks old. In my ‘Introductory Treatise’ I have alluded to the case of the girl Riordan, who not only passed per anum upwards of 1200 larvæ, but also several perfect insects. The case was first reported by Pickells, Thomson, and Bellingham. One of the other authentic cases, in which only a few larvæ were present, was recorded by Patterson, of Belfast, and the third case by Bateman. Mr Hope’s ‘Catalogue’ originally appeared in the ‘Transactions of the Entomological Society,’ being afterwards published in the pages of the ‘London Medical Gazette,’ 1837. Patterson’s case was also, I believe, first communicated to the Entomological Society.

As regards the mode in which the maggot gained access to the child in Horne’s case, it was not easy to decide; but in the case of the girl Riordan the mode of ingress was sufficiently explained. The _Blapsidæ_, as a family, are closely allied to the meal-worms, and, like most of the _Tenebrionidæ_, are black and foul-smelling beetles, frequenting dark and damp situations, from which they escape only at night. The family comprises numerous species, of which probably not more than three are found in this country. They are abundant in Africa, especially in Egypt, where (according to Fabricius, as quoted by Westwood, Figuer, and others) the women eat _Blaps sulcata_ cooked with butter in order to make themselves grow fat. The insects are also employed as specifics against ear-ache and the bite of the scorpion. The superstitious notion of a “charm” is generally at the bottom of these domestic remedies. In the girl Riordan’s case, as Westwood observes (when epitomising Pickell’s account), the parasites, as such, “probably originated in an absurd and superstitious practice, which she had for some time followed, of drinking daily for a certain time a quantity of water mixed with clay, taken from the graves of two Catholic priests, and eating large pieces of chalk. One of these beetles was immersed repeatedly in spirits of wine, but revived after remaining therein all night, and afterwards lived three years.” The intolerance of light shown by the perfect insect seems to be equally shared by the larva. Of this fact I had repeated evidence by observing the behaviour of the living specimen sent to me by Dr Horne. Thus, when, on February 5th, 1877, I placed the maggot on the surface of some moist mould, scarcely half a minute elapsed before it commenced to bore its way downwards, and in less than a minute all but the tip of the tail had disappeared. In like manner, when, on the 7th, I raised the lid of the box, and found the maggot on the surface of the soil, it almost instantly proceeded to bury itself. Hope’s list records no less than nine instances of parasitism in man from the larvæ of _Tenebrio molitor_, and he gives a score of other Coleopterous insects which he regarded as human “intestinal worms.” Undoubtedly a large number of insect larvæ do get introduced into, and actually live within the human intestines.

Numerous cases of this sort have come under my observation, but it often requires a profound knowledge of entomology to determine the species. Several examples of œstridean larvæ occur amongst them. For one example of _Œstrus hominis_ I am indebted to Mr Higginson, of Liverpool, who obligingly supplied me with notes of the case. Dr Kirk presented me with a small bot which he removed from Livingstone’s leg. I afterwards deposited the African bot, in his name, in the Hunterian collection. Bates speaks of an Œstrus in Brazil producing boils in human flesh. Westwood quotes similar instances. Of these, one was extracted from the thigh by Dr Brick. Mr Doubleday, the entomologist, extracted one from his own leg, and M. Goudot, another entomologist, was also victimised in the same way. Both of these _savans_ were travelling in America at the time. Two cases from South America were also recorded by Howship. In one the larva lodged in the back; in the other in the scrotum. Humboldt noticed that the Indians were much infested by Œstridæ. Three cases are severally recorded by Roulin, Guérin, and Audouin. Mr Stroop also mentions a case in which an Œstrus was removed from an ulcer on the shoulder of a boy in Texas. Another kind of bot known as the Macaco worm (_Cuterebra noxialis_) occasionally attacks man, but more frequently cattle and dogs. For one example, taken from the leg of a negro, at Belize, British Honduras, I am indebted to Dr Dobson (A. M. D., Netley). Hope’s list records five cases of bots of _Œstrus hominus_, one of _Œ. Guildingii_, one of _Œ. bovis_, and thirteen others (belonging to the same genus) as having been noticed in man. Since his time many additional cases have been recorded by J. M. Duncan and others. In like manner a legion of cases in which the maggots of various Muscidæ have been noticed, either in, upon, or from the human body. At a meeting of the American Academy in April, 1859, Dr Leidy showed some larvæ of the bluebottle fly vomited by a child; five larvæ of the flower-fly (Anthomyia) from a physician’s own person (which had produced choleraic symptoms); and nine examples of _Cuterebra noxialis_. I have myself encountered numerous insect larvæ in medical practice. Amongst others I have obtained the larvæ of _Anthomyia canalicularis_ in six or eight separate instances. One set of specimens, identified by Wunderlich, was sent to me by Dr Brandt, of Oporto. Drs Duffin, W. Fox, and Leared have supplied me with others. The larvæ described in Farre’s case, not being setose, must be referred to one or other of the Muscidæ proper. Mr Hope gave nearly forty cases of this kind, referable to eight different species of fly, and, as already implied, I have myself collected a great variety of the maggots of Muscidæ passed by the bowel, besides others obtained either from beneath the skin or from open ulcerations.

The flies hitherto noticed as supplying parasitic maggots in man are _Musca domestica_, _M. carnaria_, _M. larvarum_, _M. nigra_, and perhaps _M. Cibaria_, _M. stabulans_, and _M. Cæsar_. This last, a handsome fly, is the species which proves so troublesome to sheep. The habit which flies have of depositing their eggs in open wounds, when the victims are asleep, is a fertile source of this kind of parasitism. Some of the instances recorded by Kirby and Spence are revolting in the extreme. They quote the cases which came under Mr Sell’s notice in Jamaica. In one instance the flies were hatched in a neglected blister on the chest; in another from the gums and inside of the cheek; and in a third, from the nostrils of a negro, from whom 235 larvæ were expelled. The case of the Lincolnshire pauper, Page, who was literally eaten up by maggots, is almost incredible. An equally horrible instance, however, is recorded by Cloquet. It is said that the Jamaica cases were all due to the larvæ of the bluebottle fly (_M. vomitoria_). An instance of the same kind has been recorded by Mr Knox (A. M. D.). Sufficiently revolting as these cases are, the horrors attending them are eclipsed by the habits of the larvæ of _Lucilia hominivora_. The best accounts of its habits are those by M. Coquerel, M. Saint-Pair, and M. Vercammer. The insects lay their eggs in the mouth and nostrils, and when the larvæ escape they devour the tissues surrounding the buccal cavity, the pharynx, glottis, frontal and nasal sinuses, even reaching the sockets of the eye. Several Cayenne convicts have perished from the maggots of this fly, which is also prevalent in Mexico. These are not, however, the only instances of maggots gaining access to the nasal chambers. In a case recorded by Dr Astros, of Aix, 113 were discharged from the nose of a woman; and M. Legrand du Saulle records an instance where a number of larvæ occupied the frontal sinuses of a girl, nine years of age. The larvæ produced persistent headache and convulsions. In the case recorded by Wohlfart, 18 larvæ were discharged from the nose of an old man, and in the example given by Latham several larvæ were obtained from the frontal sinuses of a woman. Bracey Clark also gives an instance in which a bot was taken from a woman’s jaw. Not improbably the well-known Indian disease, termed peenash, or worm in the nose, is due to the presence of Œstridean larvæ. Cases by Rustomjee and Lahory are quoted below. Possibly Stockett’s is another of the same order. The case by Kilgour (Bibliog. No. 34) may be another. I may add that Moquin-Tandon gives an instance of the discharge of seventy-two bots, resembling those of the sheep, from a woman’s nose (‘Journ. de Vandermonde’). The rat-tail maggots or larvæ of _Helophilus_ are parasitic. Two or three instances have been recorded from the horse. I possess one from the human intestine. Kirby also quotes an instance in which _Heloph. pendulus_ was obtained from the stomach of a woman (‘Philos. Mag.,’ vol. ix, p. 366).

A vast number of non-parasitic insects are injurious to man and beast. Inasmuch as they subsist at the expense of their victims and also adhere to his person during their attacks for a shorter or longer time, they, like the leeches, may be spoken of as free parasites. The leg-sticker (_Stomoxys calcitrans_) penetrates through thick stockings, causing blood to flow freely. The clegg of the West Highlands (_Hæmatopota pluvialis_) also violently attacks man and beast, especially horses. The mosquito (_Culex anxifer_), the gnats (_C. pipiens_, _C. annulatus_, and _C. pulicaris_), and the midge (_Chironomus plumosus_) need only be mentioned. The creeping gnat (_Simulium reptans_) is also very annoying in Sweden. The rôle of the mosquito, as itself constituting a parasite-bearer, will be again referred to in the closing pages of this work (Book II, Section V). The bites of the tsetse (_Glossina morsitans_), though so destructive to the horse, ox, sheep, and dog, are not dangerous to man himself. According to Sir S. Baker, the seroot-fly, or zimb of Bruce, which is a species of _Pangonia_, is excessively annoying to travellers in Abyssinia. Amongst the hemipterous insects the common bug (_Acanthia lectularia_) is sufficiently blood-thirsty; but there is a far more sanguinary species of this kind in South America. This is the pampas benchucha (_Conorhinus nigrovarius_). Our distinguished countryman, Darwin, in his ‘Voyage,’ speaking of these wingless insects, says:--“Before sucking they are quite thin, but afterwards become round and bloated with blood. In less than ten minutes the insect is changed from being as flat as a wafer to a globular form.” This insect somewhat resembles our water-scorpion (_Nepa cinerea_), a non-parasitic species whose bite causes severe pain, as does also the wound inflicted by the water-boatman (_Notonecta glauca_). There are other species of bug, such as the _Acanthia rotundata_ of Réunion Island and _A. ciliata_ of Kasan, the bites of which are worse than that of the common species. The fly-bugs also, such as the _Reduvius personatus_, so common in France, and the _R. amænus_ of Borneo and Java, attack man, although their especial habit is to attack and destroy other insects, including bugs themselves. Other species or varieties of Reduvius (_R. cruentus_, and _R. serratus_) attack man. The last named is an Indian form, capable, it is said, of producing an electric shock.

Passing to the fleas, the most important and truly parasitic form is the chigoe or gigger (_Pulex penetrans_). This abounds in tropical America and the West Indies. The female insects only attack man, and this they do for the purpose of securing a lodgment for their offspring. They attack especially the soles of the feet, between the toes and near the nails. In bad cases the whole of the foot becomes affected. After the insect has penetrated the skin its body swells enormously and becomes a mere bag of eggs. This swelling causes active inflammation, which terminates in suppuration and the formation of open ulcers. The chigoe also attacks various animals. In addition to the common flea (_P. irritans_) other species infesting animals are said to attack man occasionally. As regards those degraded types of insects known as lice I can only afford space to remark that five species have been recognised as human. These are the head-louse (_Pediculus capitis_); the louse of the eyelids (_P. palpebrarum_); the clothes-louse (_P. vestimenti_); the distemper louse (_P. tabescentium_); and the pubic louse (_P. inguinalis_). The distress these creatures occasion is only fully known to physicians who deal with the obstinate cutaneous affections caused by their presence (_Phthiriasis_). Some of the lice found on negroes and Greenlanders are regarded as distinct varieties. Lice are abundant on animals, and some of the species are apt to transfer themselves from one host to another. Thus the _Ornithomyia avicularis_ of cage birds has been found on man, whilst one or more of the numerous species infesting the common fowl are, by transfer, apt to produce a severe phthiriasis in the horse. The lice of the fowl belong to the genera _Leipurus_, _Liotheum_, _Menopon_, _Philopterus_, _Goniodes_, and _Goniocotes_. The unsuitableness of man’s person as a habitation for bird-lice should, however, check the fear which many persons have of handling fresh-killed poultry and game birds. Poultry lousiness in man is probably impossible from this source.

BIBLIOGRAPHY (No. 40).--_Arture_, “Obs. sur le ver nommé Macaque,” in ‘Mém. Acad. des Sci.,’ Paris, 1753.--_Bates_, “Œstrus in Man,” ‘The Naturalist on the Amazons.’--_Beneden, Van_, ‘Animal Parasites and Messmates,’ 1876.--_Idem_ (with _Gervais_), ‘Traité de Zool. Méd.’--_Blood, M._, “Case of Larvæ (_Musca sarcophaga_) expelled alive in the Fæces,” ‘Beale’s Arch. of Med.,’ vol. iii, p. 134, 1862.--_Brinton_ (similar case), ‘Arch. of Med.,’ vol. iii, p. 133, 1862.--_Bouyer_ (quoted by Figuer), ‘Tour du Monde,’ p. 318, 1866.--_Clark, Bracey_, in ‘Linn. Trans.,’ vol. iii, 1797 (the jaw-case at p. 323), and vol. xv, 1827.--_Idem_, ‘Essay on Bots,’ 1815.--_Cloquet, J._, “Case of Blindness from Worms (larvæ of Musca) in the Eyes,” from ‘Arch. Gén. de Méd.,’ in ‘Lancet,’ 1828.--_Cobbold_, “On _Blaps mortisaga_ as a Human Parasite,” ‘Brit. Med. Journ.,’ 1877, p. 420.--_Idem_, “Entoz.” (‘Hope’s List.’), p. 416.--_Idem_, in ‘Worms’ (“Leptus,” &c.), p. 140, 1872.--_Coquerel_ (quoted by Figuer).--_Cormack, J. R._, “Exhibition of a Larva (_B. mortisaga_) passed by a Child,” ‘Month. Journ. Med. Sci.,’ vol. i, 1841.--_Crumpe, S._, “History of a Case in which Worms (larvæ of a beetle) were discharged from the Stomach,” from ‘Trans. of the Roy. Irish Acad.,’ vol. vi, in ‘Med. Facts and Observ.,’ vol. viii, p. 229, 1800.--_Denny_, ‘Monog. Anoplurorum Brittaniæ,’ 1842.--_Duncan, J. M._, “On the Occurrence of Bots in the Human Subject,” ‘Edin. Vet. Rev.,’ vol. i, p. 275, 1858-59.--_Idem_, “The Larva of _Œstrus bovis_ in the Human Subject,” ‘Rep. of Edin. Med.-Chir. Soc.,’ in ‘Month. Journ. of Med. Sci.,’ July, 1854.--_Farre, A._, “On the Larva of _Anthomyia canalicularis_,” ‘Micr. Journ. and Struct. Rec.,’ 1841, p. 129, and in ‘Trans. of Micr. Soc. of Lond.,’ orig. ser., p. 51, 1844.--_Figuer_, in ‘The Insect World’ (good figs.), Janson’s edit., 1869.--_Furlonge_, “Anat. of Pulex,” in the ‘Journ. of the Queckett Club,’ vol. iii.--_Geer, De_, ‘Mémoires pour servir à l’Histoire des Insectes,’ 1773.--_Gervais_ (see Van Beneden).--_Hill_, “Account of the Larva of a supposed _Œstrus hominis_, or Gad-fly, which deposits its Eggs in the bodies of the human species, with particulars of a Case,” ‘Edin. New. Phil. Journ.,’ vol. xxii, p. 284, 1830.--_Hilaire_ (see St Hilaire).--_Hope_, “Tables of Cases of (spurious) Intestinal Worms,” ‘Lond. Med. Gaz.,’ 1837-38.--_Hoppe_, “Case of Larvæ of Insects (_Musca stabulans_) passed by Stool,” from ‘Bibl. für Läger,’ in ‘Med.-Chir. Rev.,’ 1842.--_Hopper, R. S._, “Insects (Stratiomis) voided with Urine,” edit. note in ‘Micr. Journ. and Struct. Rev.,’ p. 160, 1841.--_Joly_, ‘Recherches sur les Œstrides en général,’ &c., Lyons, 1846.--_Keferstein_, ‘Sur l’Oistros,’ Isis, 1827.--_Kirby_ (and _Spence_), ‘Introd. to Entomology,’ 7th edit., 1856.--_Knox, M._, “Maggots, the larvæ of the Bluebottle Fly, in Syphilitic Ulceration of the Throat,” ‘Lancet,’ Oct. 6, 1877, p. 514.--_Lahory, B. T. C._, “On _Peenash_, or Worms in the Nose,” ‘Ind. Ann. of Med. Sci.,’ 1855, and ‘Edin. Med. Journ.,’ 1857.--_Leach_, “Œstridæ,” in ‘Wernerian Trans.,’ 1817.--_Leidy_, in ‘Proc. Phil. Acad. Nat. Sci.,’ 1859, p. 7.--_Maclean_, “On the Oistros,” ‘Linn. Trans.,’ vol. xiv, 1824, and in ‘Zool. Journ.,’ vol. i and iv.--_Metaxa_, “Vom Œstrus (u. s. w.),” in ‘Neuen Nord. Beitr.,’ Bd. i, and in ‘Mém. de Zool. Med.,’ Rome, 1835 (quoted by Westwood).--_Moquin-Tandon_, ‘Med. Zool.’ (l. c., Bibl. No. 38).--_Newport_, art. “Insecta,” ‘Todd’s Cyclop.,’ 1839.--_Rustomjee, B._, “Case of Worms in the Nose, or ‘Peenash,’” in ‘App. to Bomb. Med. and Phys. Soc. Trans.,’ No. vii, new ser., p. 21, 1861; see also Lahory, on ‘Peenash.’--_Saint-Hilaire_, “Sur l’Œstre chez l’homme,” in ‘Ann. Soc. Ent. de France,’ 1833.--_Say_, “Brick’s Case,” in ‘Trans. Acad. Nat. Sci. Phil.,’ vol. ii.--_Sells_, in ‘Trans. Entom. Soc. Lond.;’ see also Lemprière’s ‘Diseases of the Army in Jamaica,’ vol. ii.--_Stockett, T. H._, “An account of a Headache cured by the discharge of a Worm (?) from the Nose,” ‘Med. Com.,’ vol. xix, p. 157, 1794, and in ‘Trans. Coll. of Phys. Phil.,’ vol. i, part i, p. 181, 1793.--_Stroop, St J._, “Œstrus,” in ‘Amer. Naturalist,’ vol. vii, p. 437.--_Tanner_, “On Lice,” in his ‘Pract. of Med.,’ vol. ii, p. 429, 6th edit., 1869.--_Westwood_, in his ‘Classification of Insects,’ vol. ii, 1840.--_Wohlfart_ (quoted by Moquin-Tandon).--_Yule_, “Case of Larvæ of Insects in the Human Stomach,” ‘Edin. Phil. Journ.,’ and ‘Lond. Med. Repos.,’ 1825.

SECTION IV.--PART VI.--PROTOZOA (Psorospermiæ, Gregarinidæ, &c.).

The scope of this work does not demand that I should comprise within its limits any vegetable parasites; nevertheless, I must needs refer, however briefly, to certain confervoid and sarcodic organisms, which, for the most part, lie on the borderland of the animal and vegetable kingdoms. Professor Cohn regards the bacteria as allied to the Oscillitoriaceæ. He puts them in his order _Schizosporeæ_. It is of little moment, practically, where these protista forms are placed. Unquestionably many of them are parasitic, as they live in the tissues, fluids, and secretions of animal bodies, including man. Their presence in cattle is associated with an anthracoid disease (charbon), whilst in the human body they have been detected in connection with zymotic affections. They have been found by Cohn, Sanderson, Klebs, Chauveau, and others, either in the lymph of vaccine pustules, or in the miliary eruptions of typhus fever. Professor Beale, who was one of the first to observe these special organic particles in vaccine lymph, denies that they are true Bacteria; and, indeed, he warmly disputes the inferences that have generally been drawn from the fact of the presence of such particles in lymph, blood, and other nutrient fluids. The best known and defined forms are _Bacterium termo_ and _Bact. lineola_, which are concerned in the production of putrefaction, _Bacillus anthracis_, found in the blood of animals suffering from carbuncular disease, _Micrococcus septicus_, found in typhus and pyæmia, _M. vaccinæ_ of cow pox lymph, and _M. diphthericus_, in diphtheria. As regards their prevalence in certain forms of relapsing fever, Sanderson states that Dr H. V. Carter, of Bombay, examined the blood of 250 fever patients and found _spirilla_ in nearly every instance. From the independent observations of Pasteur, Sanderson, Lister, Tyndall, Bastian, Eberth, Roberts, Davaine, and many others, it seems clear that the Bacteria and their allies play an important part in association with certain morbid states. However, as regards the etiology of the maladies in which these organisms are found, it is perhaps too early to speak with absolute confidence. The subject cannot be dealt with here; moreover, it is outside the range of my personal investigations.

Passing to those protozoa which, although retaining some vegetable affinities, are more or less distinctively animal, I notice the obscure organisms termed psorosperms. In dealing with these I shall treat of the forms that infest both man and animals, confining my remarks to such as happen to have come under my own observation.

In the year 1865 the public were thoroughly roused to a sense of danger arising from the consumption of meat. The panic originated with the outbreaks of trichiniasis in Germany. During the excitement which subsequently prevailed at the time of the rinderpest, all sorts of erroneous notions took possession of the popular mind, and the errors were stimulated by writers ignorant of helminthology. In January, 1866, I published a few observations, the purport of which was to show that certain microscopic organisms found in animals dying from cattle plague were harmless “parasitic Protozoa,” possessing more or less striking vegetable affinities. About a week previously some interesting researches on these so-called cattle-plague bodies had been published by Dr Beale. Those who first saw these bodies thought they had stumbled upon organisms new to science. I showed that similar or analogous organisms were to be met with in a great variety of animals, and likewise in the human body. They had been called worm-nodules, worm-nests, egg-sacs, eggs of the common fluke, young “measles,” corpuscles produced by muscular degeneration, psorospermiæ, stages of growth of gregarinæ, amœboid bodies, and so forth. In so far as the higher animals were concerned, Dujardin was the first to describe them. He found these organisms in a mole. This animal, however, having been fed upon earth-worms known to harbour such parasites, there was no difficulty in accounting for the source of the psorosperms.

In 1853 Hessling discovered psorospermial sacs in the muscular substance of the heart, not only of the ox, but also of the sheep and roe. By him they were regarded as evidences of muscular degeneration. About ten years previously Miescher found similar bodies in the muscles of the mouse.

In 1857 Rainey described similar structures taken from the flesh of swine; and, in his memoir, he went so far as to maintain that these bodies were early stages of development of the common pork-measle. In the year 1858 Gubler wrote an important paper on this subject, in which he related a case where twenty cysts existed in the human liver. The cysts were of great size, mostly as large as a hen’s egg, one of them being some six inches in diameter. Naturally, the largest had been diagnosed as an ordinary hydatid. However, on evacuating their contents (post mortem), they were found to harbor enormous quantities of minute corpuscles strictly analogous to those usually obtained from psorospermial sacs. Gubler believed he had stumbled upon masses of eggs of _Distoma hepaticum_, but in this he erred. Shortly after Gubler’s discovery similar bodies from the human liver were described by Virchow; and in 1862, the subject was followed up by Dr Dressler, of Prague. Dressler found in the human liver a number of pea-shaped bodies, the milky contents (_breisubstanz_) of which displayed a multitude of the characteristic corpuscular elements referred to. These particles, already considered as equivalent to, if not identical with, the so-called pseudo-navicellæ of gregarinæ, were soon encountered by a variety of independent observers. Thus, Leuckart noticed these bodies in various animals; but with caution remarked:--“Concerning the nature of these formations I will not decide. To be candid, however, it appears to me to be in no way made out whether the psorospermiæ are to be considered as the result of a special animal development, whether they, like pseudo-navicellæ, are the nuclei of gregariniform productions, or whether they are the final products of pathological metamorphosis.” Leuckart found these organisms in the intestines of a trichinised dog, also in a sheep and pig fed with Trichinæ. He also found them in the muscles of another pig fed with psorosperms, and likewise in the liver of various rabbits. He remarks that in swine these parasites are more abundant than measles. They were present in five of eighteen pigs, and also in two out of four sheep, whose flesh was especially examined. The observations of Lindemann at Nischney-Novgorod are particularly interesting. This medical officer discovered psorospermial sacs attached to the hair of a girl who was being treated in hospital for chlorosis. The sacs in question bore close resemblance to the bodies which we found in abundance in diseased and healthy cattle. It would further appear, from Lindemann’s observations, that the affection is not very uncommon amongst the Russian peasants.

In connection with and attached to the same parasitically affected hairs Lindemann also noticed several movable gregarinæ; and partly from this circumstance he was led to believe in the existence of a genetic relation subsisting between the two kinds of bodies. He further expressed his conviction that the people contracted the disease by washing themselves with water in which gregarinæ abounded. Lindemann moreover refers to Lebert as having noticed similar parasites in a case of favus, and concludes that these organisms are of a vegetable nature. His opinion, though not shared by the majority of parasitologists, is nevertheless supported by the views of Robin, Leydig, and others. Of still higher interest are the observations of Lindemann respecting the occurrence of psorospermiæ in the capsule of the kidney of a hospital patient who died with Bright’s disease. The sacs in this case were remarkably small; nevertheless their corpuscular contents indicated their true nature. The pseudo-navicellæ measured only 1/5000″ in diameter. Amongst other contributions of interest I may refer to those of Dufour, J. Müller, Creplin, Kölliker, Keferstein, Stein, Drummond, Lieberkühn, and E. Ray Lankester. I doubt if the vegetable organisms described by Prof. W. T. Gairdner can be referred to this group of parasites. At all events, by whatever name these spurious entozoa are called, they were first discovered by Dufour in insects, by Müller in fishes, by Miescher in the mouse, by Dujardin in the mole, by Hessling in the larger quadrupeds, and by Gubler in man. The results of my own examinations may be briefly re-stated. In the flesh of cattle I found psorospermial sacs varying from 1/120″ to 1/12″ in length, and in that of sheep from 1/220″ to 1/80″. The bodies were enclosed in well-defined transparent envelopes, and their contents exhibited indications of segmentation. In some specimens the segments displayed themselves as a complete cell-formation, the contents of each cell being uniformly granular. Under the 1/4″ objective the contained granules were clearly visible, and on rupturing the sac their peculiar characters were at once manifest, each granule or corpuscle represented a pseudo-navicel, all displaying a tolerably uniform size, averaging 1/2000″ in diameter. Some of the corpuscles were round, others oval, several bluntly pointed at one end, many curved and fusiform, not a few being almost reniform. Highly refracting points or nucleoli were visible in their anterior.

Turning to the practical aspect of the subject, I remarked that these bodies had nothing to do with the cattle plague. No one who carefully examined the flesh of animals that had died of rinderpest had failed to discover them; yet, in one or two instances they appear to have escaped notice. When it is considered how long it takes us to examine a few grains weight of muscle carefully, it is obvious that the body of a large beast might contain many hundreds of these organisms without our being able to detect their presence, except by a prolonged investigation. In the few rinderpest beasts, portions of whose flesh I submitted to the microscope, I should say there were not more than 100 of these bodies in one ounce of meat; but in the heart of a healthy sheep (which I afterwards ate) I calculated there were about 1000 parasites to the ounce, and in the heart of a healthy bullock (which likewise served me for a meal) their numbers were rather in excess of those in the sheep. Altogether, at two meals, I could not have swallowed less than 18,000 of these psorosperms. Consumers of beef, mutton, and pork eat these bodies every day, but they take no harm because the parasites in question are not true helminths. Fine healthy beef has been returned to the butcher when it was as good as any other meat in the market. I have examined various kinds of meat, such as veal, pork, and mutton, but in none have I found so great an abundance of psorosperms as in beef, which was, notwithstanding, perfectly healthy and sound. I calculated that in one instance a single ounce of the flesh contained upwards of 2000 parasites. There is practically no limit to the extent of this kind of parasitism, and there is no organ of the body in which psorosperms may not be found. Moreover, the forms they display are exceedingly various. Psorosperms have been found by Siedamagrotzky in the muscles of the horse, and not very long ago, through the help of Professors Simonds and Axe, I had the opportunity to examine some peculiar worm-like structures which occupied the mitral valve of a horse. To the naked eye they looked like coiled nematodes, but I was soon convinced that they formed a peculiar type of psorosperm. A complete view of these bodies was a matter of great difficulty owing to the delicate nature of their limiting membrane and to the confusion of markings produced by the interlacing of the fibres of the chordæ tendinea. At length, by spreading a portion of the membrane of the valve over a large glass slide, and by allowing it to dry slowly, I found that the vermiform body presented neither beginning nor end. The appearances were curious and puzzling. The organism formed a flattened tube or sac, almost uniform in width and variously twisted upon itself. From the main tube there projected several hernia-like secondary loops or branches, most of them presenting less than half of the thickness of the former. These peculiarities, however, can hardly be understood without reference to the original illustrations. That these secondary coils were not of the nature of hernial protrusions was evident, not alone from the nature of their contents, but also from the fact that they showed distinct anastomoses. In fact, the parasite was a simple sac or bag with branches.

On puncturing the main tube with a fine needle a small quantity of tenacious creamy fluid made its escape. This, under Ross’s 1/4-inch lens, resolved itself into a few excessively delicate sarcode globules surrounded by fine granules. The granular matter displayed a tendency to collect itself in the form of oval masses without showing any trace of a limiting border. One of these masses, measuring 1/250″ in length, I examined under a Wasserlein-objective, when I further ascertained that the elementary particles or granules were uniformly oval in shape, rather highly refractive, their size scarcely exceeding 1/8000″ in diameter. The sarcode corpuscles, on the other hand, were of different sizes, ranging between 1/3000″ and 1/1600″ in diameter.

From the facts thus elicited, negative as they were in respect of helminthic structure, I could see no escape from the conclusion that we had to deal with a new form of psorospermial bag, whose granular contents consisted of excessively minute pseudo-navicellæ. In the centre of the largest hernia-like loop there was a clear oval disk, which at first brought to my mind the nucleus of _Monocystis_ infesting the earth-worm, but it was merely a vacuole.

The case recorded by Gubler reminds me of another remarkable instance of psorospermial cysts, in this case associated with true hydatids. In 1873 Dr Whittell sent me particulars of a case in which the contents of an hydatid of the liver (drawn off, during life) consisted of shreds of a true hydatid, a few echinococcus-hooklets, together with multitudes of spindle-shaped amœboid particles of excessive minuteness and delicacy. The bodies, floating in a transparent fluid, formed a thick milky or creamy fluid, resembling pus in appearance; but there was no trace of pyæmia. Judging from Dr Whittell’s figures, he must also have found a solitary microscopic nematoid hæmatozoon, the nature of which was not clear to him. I believe it to have been a specimen of _Filaria sanguinis hominis_. Be that as it may, the case is altogether unique and deserves further elucidation.

As regards the higher forms of protozoa it must suffice to allude to the _Cercomonas hominis_ of Davaine, found in the dejections of cholera patients, to the _Cerc. urinarius_ of Hassal and _C. saltans_ of Ehrenberg, to the _Trichomonas vaginalis_ of Donné, detected in the vaginal mucus, and to the _Balantidium coli_ of Claparède and Lachmann, originally found by Malmsten in the human colon. The _Balantidium_, or _Paramæcium coli_, has frequently been observed in the evacuations of fever patients, and it has also been found by Dr Treille in patients suffering from the Cochin-China diarrhœa. Monads have also been found in the stomach and intestines of the hog and various other animals. Infusorial parasites are particularly abundant in batrachians, the _Bursariæ_ of frogs and toads being familiar to every helminthologist.

BIBLIOGRAPHY (No. 41).--_Arloing_ (and _Tripier_), in ‘Gaz.-hebd.,’ 1873, p. 574 (quoted by Davaine).--_Balbiani_, ‘Compt. Rend. Soc. Biol.,’ 1867, p. 103 (quoted by Davaine and Bastian).--_Bastian_, “On the Nature of the so-called _Sarcina ventriculi_,” ‘Brit. Med. Journ.,’ Feb. 3, 1872.--_Idem_, “On Heterogenesis in its relation to certain Parasitic Diseases,” ‘Brit. Med. Journ.,’ Feb. 24 and April 20, 1872 (see part iv, p. 417, with figs. from Balbiani).--_Beale, L._, “Entozoon-like bodies in Muscles,” in the ‘Microscope in Medicine,’ 4th edit., p. 485, 1878.--_Idem_, “Bacterium Hypothesis of Contagium,” _ibid._, pp. 313-321.--_Burnett, W. T._, “On Psorospermia, Mermithes, &c.,” in a paper entitled ‘Reviews and Records in Anat. and Physiol.,’ in ‘Amer. Journ. of Sci. and Arts,’ vol. xviii, 2nd ser., p. 104, 1854.--_Carter, H. V._, “On Spirilla,” quoted by Sanderson in ‘Brit. Med. Journ.,’ Nov. 17, 1877, p. 700.--_Cobbold_, “Remarks on Spurious Entozoa found in Diseased and Healthy Cattle,” ‘Path. Soc. Trans.,’ vol. xvii, p. 452, 1866, and ‘Lancet,’ Jan. 27, 1866, p. 88; see also Prof. J. Gamgee’s work on the ‘Cattle Plague.’--_Idem_, “On Worm-like Organisms in the Mitral Valve of a Horse,” ‘Veterinarian,’ Sept., 1877.--_Idem_, “On Psorospermiæ in the Eye of the Cod (Morrhua),” ‘Linnean Society’s Proc.,’ May, 1862, and in ‘Intellectual Observer,’ 1862, p. 199.--_Cohn_, ‘Nova Acta,’ xxiv, s. 103 (quoted by Leuckart), Bd. i, s. 139.--_Creplin_, ‘Wiegmann’s Archiv,’ 1842, s. 61.--_Davaine_, l. c., 2nd edit., “Synops. xxi” (with bibliog. refs.), 1878.--_Donné_, ‘Cours de Microscopie,’ Paris, 1847, p. 157.--_Dressler_, quoted by Leuckart, Bd. i, s. 141.--_Drummond_, ‘Edin. Phys. Rep.,’ 1852,--_Dufour_, ‘Ann. des Sci. Nat.,’ 1837.--_Dujardin_, ‘Traité’ (l. c., see Bibl. No. 1).--_Eberth_, ‘Zur Kentniss Bacteritischer Mykosen,’ 1872.--_Eimer_, ‘Ueber Psorospermien,’ 1870.--_Gairdner_, ‘Edin. Phys. Soc. Rep.,’ 1853.--_Gluge_, “Cysts in Sticklebacks,” ‘Bullet. Acad. Roy. des Sci. de Bruxelles,’ 1838.--_Gubler_, ‘Mem. Soc. Biol.,’ 1859, p. 657, and in ‘Gaz. Méd.,’ 1858, p. 61.--_Harz, C. O._, “Eine neue Mikrococcusform im lebenden Thierkörper,” ‘Deutsche Zeitschrift für Thier-Medicin und vergleichende Pathologie,’ f. Novemb., 1878.--_Hessling_, ‘Sieb. u. Köll. Zeitsch.,’ 1853, p. 196.--_Henle_, ‘Müller’s Archiv,’ 1845.--_Hollis, W. A._, “What is a Bacterium?” repr. in the ‘Veterinarian,’ p. 205, 1875.--_Keferstein_, ‘Götling. gelehrte Anzeigen,’ 1862.--_Kloss_, ‘Ueber Parasiten (u. s. w.)’ (quoted by Davaine).--_Knoch_, ‘Journ. de Russ. Kriegs. dep.,’ Bd. xcv, 1866 (quoted by Leuckart and by Davaine).--_Kölliker_, in ‘Zeitsch.’ (by Sieb. and Köll.), 1848-49.--_Lambl_, ‘Prager Vierteljahrschrift,’ 1859.--_Lankester, E. R._, “Recent Researches on Bacteria (with copious references),” ‘Quart. Journ. Micr. Science,’ Oct., 1878.--_Lebert_, ‘Phys. Pathologique’ (quoted by Leuckart).--_Leidy_, “Gregarina,” ‘Amer. Phil. Trans.,’ 1851.--_Leisering_, “Bericht (u. s. w.),” in ‘Sachsen,’ 1865.--_Leuckart_, l. c., Bd. i, s. 135 and 740, and Bd. ii, s. 842 _et seq._--_Leydig_, ‘Müller’s Archiv,’ 1851, s. 221, in ‘Micr. Journ.,’ 1853, p. 206, and in ‘Arch. f. Anat. und Phys.,’ 1863, s. 191.--_Lieberkühn_, ‘Müller’s Arch.,’ 1854.--_Lindemann_, ‘Bullet. Soc. imp. des Naturalistes de Moscow,’ 1863, and in ‘Gaz. Méd. de Paris,’ 1870, p. 86.--_Lister, J._, “Natural History of Bacteria,” ‘Micr. Journ.,’ Oct, 1873.--_Malmsten_, “_Paramæcium coli_” (quoted by Davaine, l. c., 2nd edit., p. 67).--_Miescher_ (quoted by Leuckart and Siebold).--_Müller_, ‘Archiv,’ 1841, s. 477.--_Rainey_, ‘Phil. Trans.,’ 1857.--_Rayer_, “Singulière éruption sur un véron (Cyprinus),” ‘Arch. de Méd. Comparée,’ Paris, 1842 (quoted by Davaine).--_Rivolta_, “Psorospermi, &c.,” trans. in ‘Journ. des Vét. du Midi,’ 1869, pp. 445 and 521.--_Robin_, ‘Les Végét. Paras.,’ 2nd edit., p. 291.--_Sanderson_, in ‘Privy Council Reports,’ 1874.--_Siedamagrotzky_, in ‘Recueil de Méd. Vét.,’ 1872, p. 460.--_Stein_, in ‘Müller’s Arch.,’ 1848, and ‘Ann. Nat. Hist.,’ 1850.--_Idem_, “Abhandl. d. k. Böhmischen Gesellsch.,” x, s. 69, oder Lotos, 1859, s. 57 (quoted by Leuckart, Bd. i, s. 151).--_Steinberg_, ‘Walter’s Zeitschr. f. die moderne Medicin,’ 1862, and in Leuckart, Bd. ii, s. 844.--_Stieda_, ‘Arch. f. pathol. anat.,’ Bd. xxxv, and in Leuckart, Bd. ii, s. 846.--_Suriray_, “Sur quelques parasites du lombric,” ‘Ann. des. Sci. Nat.,’ 1836.--_Virchow_, “Zur Keutniss der Wurmknoten,” ‘Arch. f. Anat. u. Phys.,’ xviii, s. 523.--_Vogel_, ‘Path. Anat.,’ i, s. 404.--_Waldenburg_, “Psorospermien,” in ‘Arch. f. Path. Anat.,’ s. 435, 1867.--_Windbladh_, also _Wising_, ‘On _Balantidium coli_’ (quoted by Leuckart, Bd. ii, s. 846-847).--_Winkler_ (see _Leisering_).

APPENDIX.--On various occasions I have dwelt upon the necessity of acquiring accurate information respecting the degree of mortality due to parasites, and in the present volume (p. 124) I have referred to the defective evidences supplied by the returns of the Registrar-General in respect of the echinococcus disease. My object is not to cast blame upon those whose duty it is to publish the returns, but rather to call attention to the advantages that would follow if the Registrar-General were supplied with full and accurate information on this head.

Through the courtesy of Mr Noel A. Humphreys I have been furnished with the following official statement of the number of _Deaths from Worms_ in England and Wales, as recorded in the Annual Reports of the Registrar-General throughout a decade of years:

+--------------+----+----+----+----+----+----+----+----+----+----+ | |1868|1869|1870|1871|1872|1873|1874|1875|1876|1877| +--------------+----+----+----+----+----+----+----+----+----+----+ |Total | 172| 148| 151| 160| 154| 183| 188| 227| 204| 225| | including-- +----+----+----+----+----+----+----+----+----+----+ |Porrigo | 15 | 13 | 9 | 9 | 9 | 14 | 5 | 16 | 7 | 13 | |Scabies | 6 | 2 | 7 | 1 | 4 | 2 | -- | 5 | 2 | 3 | |Tapeworm | 8 | 3 | 6 | 3 | 5 | 3 | 5 | 5 | 2 | 6 | |Hydatids | 20 | 20 | 33 | 37 | 41 | 34 | 29 | 43 | 31 | 51 | +--------------+----+----+----+----+----+----+----+----+----+----+

Considering the prodigious advances in helminthology during the last half century, it is certainly remarkable that under the category of “worms,” as a cause of death, only two kinds of true helminths should be mentioned in the Registrar’s record. It will also strike the experienced hospital and dispensary physician as somewhat remarkable that of the two death-producing parasites above named one of them should be the “tapeworm.” Now death from _Tænia_ is certainly a very rare occurrence, although grave nervous symptoms are not unfrequently due to its presence in man. Thus, I am inclined to regard the 46 reported instances of death from this cause as a redundant estimate. On the other hand, I am surprised to see no specified instances of death from lumbricoid Ascarides, from Oxyurides, or even from Cysticerci, which now and then take up their residence in the human brain.

As regards hydatids I believe the returns to be excessively deficient. In place of an average of 34 deaths annually from this cause in the United Kingdom I am of opinion that at least 400 deaths are due to hydatids. This opinion and the data on which it was founded were communicated by me twelve years ago to the Linnean Society, and I have since become acquainted with facts which lead me to conclude that my original estimate was very much below the mark. The post-mortem registrar of one of our large hospitals has told me that of late years as many as _ten_ deaths might be reckoned as annually due to hydatids in their institution alone. At a smaller hospital I ascertained that the average was about _four_. Obviously, if these estimates are correct, the Registrar-General’s returns for the United Kingdom do not record a tithe of the annual mortality due to hydatids. Perhaps another half century will elapse before the truth of my deductions be confirmed by the _official_ returns. For me, it must suffice to have pointed to the desirability of securing more accurate records.

By a curious coincidence I had only just sent to press the sheet of this work recording the statistics of hydatid disease in Australia (p. 123), when a paper dealing with the same subject appeared in the ‘Lancet.’ I refer to the brief memoir of Dr David Thomas, of Adelaide, South Australia, which was published on the 1st of March, 1879. Dr Thomas writes as follows:

“It is well known that Australia presents an extraordinary prevalence of hydatid disease, but, as far as I know, no definite statistics have been published to illustrate the fact. Consequently, some months ago, with the kind assistance of the Hon. W. Morgan, the present Chief Secretary of South Australia, I endeavoured to procure reports from the Governments of Victoria, New South Wales, Queensland, New Zealand, Tasmania, and Western Australia, upon this question. Unfortunately, the mode of registration of the causes of death in most of these colonies was such as prevented the necessary replies being supplied. However, it appears that in Tasmania no deaths were returned from this disease in the ten years 1867-77. During the greater part of the same period no separate classification of hydatid disease had been adopted in New South Wales; but in 1875 four deaths were attributed to hydatids; in 1876, eleven were so returned. In Victoria, however, the record of deaths from this cause is far more complete, and I append a table based upon the returns from that colony.

“One case, in which hydatid of the kidney was present, accompanied by malignant disease of bladder, with stricture, was not returned as a case of hydatid causing death.

“During the decade 1867-77, 2·5 per 1000 deaths were due to hydatid disease. In 183 out of the 307 cases the liver was either solely or conjointly with other organs the seat of disease. Holding the second place in frequency come the lungs in 71 cases, _i.e._ 53 simple and 18 complicated.”

_Table of Deaths returned as being due to Hydatid Disease in the Province of Victoria during the ten years 1867-77._

Key to Column Headings:

A = Year. I = Omentum. B = Liver. J = Ovary. C = Lungs and pleura. K = Womb.(?) D = Brain and spinal cord. L = Abdominal cavity. E = Heart and pericardium. M = Situation not recorded. F = Kidney. N = More than one organ invaded. G = Spleen. O = Total annual deaths. H = Pancreas. P = Totals

+----+---+--+--+--+--+--+--+--+--+--+--+--+-------+----------+ | A | B | C| D| E| F| G| H| I| J| K| L| M| N | O | +----+---+--+--+--+--+--+--+--+--+--+--+--+-------+----------+ |1868| 17| 5| | 1| | | | | | | 2| 7| 1(_a_)| 33 | |1869| 6| 8| 1| | | | 1| | | | 2| 1| 3(_b_)| 22 | |1870| 10| 2| 1| | | | | | | | | 4| | 17 | |1871| 4| 6| 1| | | 1| | | | 1| | 1| 1(_c_)| 15 | |1872| 19| 3| 1| 1| | | | | | | 2| 2| 1(_d_)| 29 | |1873| 17| 3| 2| | | | | | | | | 2| 5(_e_)| 29 | |1874| 21|10| 1| | | | 1| | | | | 6| 2(_f_)| 41 | |1875| 29| 7| | 2| | 1| | | 1| | 3| 2| 2(_g_)| 47 | |1876| 23| 1| | | 2| | | | | | 1| 4| 5(_h_)| 36 | |1877| 20| 8| | 1| | 1| | 1| | | 3| 2| 2(_i_)| 38 | +----+---+--+--+--+--+--+--+--+--+--+--+--+-------+----------+ | P |166|53| 7| 5| 2| 3| 2| 1| 1|1?|13|31|22 | 307 | | | | | | | | | | | | | | | |in 10 yrs.| +----+---+--+--+--+--+--+--+--+--+--+--+--+-------+----------+ |(_a_) Lungs and kidneys. | |(_b_) In two instances liver and lungs; in the third case | | liver and brain. | |(_c_) Lungs and liver. | |(_d_) Lungs and abdominal cavity. | |(_e_) In three cases liver and lungs; in one kidney and | | abdomen; in another liver, lungs, omentum | |(_f_) Liver and lungs. | |(_g_) One liver and lungs; the second case lungs and heart. | |(_h_) Three cases liver and lungs; one liver and kidney. | |(_i_) Liver and lungs. | +------------------------------------------------------------+

Such are the returns as recorded by Dr Thomas. If a comparison be instituted between the data supplied by his decade-report and those supplied by the decade-report which I have previously adduced (p. 123), it will be seen that as regards the returns for the years 1868-72, inclusive, both reports are in perfect agreement. Of still more interest also is the circumstance that whilst, on the one hand, out of the total of 307 deaths given in Dr Thomas’s table, 116 occurred during the first semi-decade (_i.e._ from 1868 to 1872, inclusive), on the other hand, no less than 181 deaths occurred during the second semi-decade (_i.e._ from 1873 to 1877, inclusive). This increase of 45 deaths during the later semi-decade is very significant. It points either to the fact of more careful returns having been made, or to an actual increase in the fatality of the disorder. Possibly both the causes alluded to operated to affect the returns. Be that as it may, Dr Thomas’s record is highly instructive, and should stimulate the profession in England to supply our Registrar-General with more precise data wherewith to construct his annual reports.