PART X (PACHYDERMATA)

Concerning the parasites and parasitic diseases of this miscellaneous assemblage of large mammals, I shall first speak of those of the proboscideans (Elephantidæ). Except by myself, they have been but little studied, and I am yet waiting for an opportunity to give further time to their consideration. When Diesing published his ‘Systema’ only two helminths were referred to the Indian elephant, namely, _Ascaris lonchoptera_ and an undescribed fluke supposed to be a distome. The whole subject requires revision, but I think the following species must, for the present at least, be allowed recognition:--_Fasciola Jacksoni_ (mihi), _Amphistoma Hawkesii_ (mihi), _Ascaris lonchoptera_ (Diesing), _Sclerostoma Spinuliferum_ (Baird), and _Dochmius Sangeri_ (mihi). Either the _Ascaris_ or the _Sclerostoma_ is probably identical with Rudolphi’s _Strongylus elephantis_.

At the Norwich Meeting of the British Association, in 1868, I exhibited two flukes received from J. S. Thacker, V.S., of the Madras Army. They were handed to me by the late Dr Baird, and were labelled “Distoma taken from liver of elephant and forwarded for classification.” I stated at the time that these entozoa were identical with certain flukes previously obtained from the duodenum and biliary ducts of an Indian elephant, and which, though carefully preserved in the Boston Museum, U.S., had never been properly described. They were only briefly noticed by Dr Jackson in his ‘Descriptive Catalogue’ of the Museum. In the summer of 1868 fifteen specimens of fluke, removed from Burmese elephants, had been forwarded to and received by Professor Huxley from Rangoon, accompanied by a statement to the effect that they were the cause of an extensive and fatal disease in Burmah. Through the kindness of Prof. Huxley I was allowed to make use of his specimens for the purpose of comparison and identification, and thus it became evident that our specimens were of the same species. It was also evident that the species could be none other than that represented by the Boston specimens. Further examination having made it clear that the organisation of these flukes departed from the ordinary distome type, I named the parasite _Fasciola Jacksoni_, at the same time offering the following description (‘Entozoa,’ Supp., 1869, p. 80):--“Body armed throughout with minute spines, orbicular, usually folded at either end towards the ventral aspect, thus presenting a concavo-convex form; oral sucker terminal, with reproductive papillæ about midway between it and the ventral acetabulum; intromittent organ 1/4″ in length; digestive apparatus with two main zigzag-shaped canals, giving off alternating branches at the angles thus formed, the ultimate cæcal ramifications occupying the whole extent of the body; length, when unrolled, from 1/2″ to 5/8″, breadth 1/3″ to 1/2″.” Now, if reference be made to the appendix of the late C. M. Diesing’s ‘Systema Helminthum,’ it will be found that Jackson’s statement had not escaped that helminthologist’s notice, though, not having seen any specimens, he was not unnaturally led to place the species amongst the distomes proper. In Diesing’s subsequently published ‘Revision der Myzelminthen,’ the species is formally characterised as the _Distomum elephantis_ of Jackson (‘Sitzungsberichte d. Math.-nat. Cl. d. k. Akad. d. Wissenchaften,’ Bd. xxxii, 1858). In my “Synopsis of the Distomidæ,” which appeared in the ‘Journal of the Linnean Society’ for 1861, I had also placed it amongst the distomes, not considering it to be a doubtful form (‘Proceed. Linn. Soc.,’ “Zoology,” vol. v, p. 9). These references exhausted the literature of the subject up to the time of the issue of my ‘Manual’ in 1873, where this fluke is again briefly noticed (p. 13). Several of Prof. Huxley’s specimens have been added to the entozoological department of the Hunterian Museum. It is clear that all these notices and descriptions point to the same parasite. The worm has since been more carefully described by Dr R. H. Fitz, from a series of dissections and preparations made by Dr H. P. Quincy, and deposited in the Warren Museum, Boston, U.S.

About the middle of June, 1875, I received a letter from General Hawkes, of the Madras Staff Corps, dated Secunderabad, May 12th, 1875, and in reference to the subject before us he writes as follows:--“My attention has been recently directed to a very unusual mortality of elephants at this station. Out of twenty-eight elephants under my charge, no less than twelve have died within the last sixteen months, whereas the average annual mortality has been hitherto only two per annum out of thirty-eight in our establishment. In every case of death there appeared to exist serious organic disease quite sufficient to account for such death, but as the mortality increased I had a post-mortem examination made in each case; and although here also organic disease sufficient to account for death was present in each case, yet in every one of these elephants we found the liver-fluke in greater or less abundance.” General Hawkes adds:--“Meanwhile I have sent you a small box containing three bottles, one containing the liver-fluke (_Fasciola Jacksoni_) referred to in your work on the parasites of domesticated animals. It seems possible that the other two species of parasites may not have been brought to your notice. Both of these, namely, the “masuri” and the “soorti,” are very common in elephants. They are both found in the intestines only. The “masuri,” when present in any quantity, cause considerable disturbance, and the animal instinctively resorts to the _eating of earth_, which it consumes in large quantities until the bowels are acted on and the worm expelled. The soorti is more common than masuri, and does not seem to inconvenience the animal very much. When expelled from the animal the soorti is a round white worm, like most of the threadworms; the masuri, on the other hand, is of a delicate flesh color.” Shortly after the receipt of this letter I obtained the entozoa in a good state of preservation. Accordingly I wrote to General Hawkes, stating that the flukes were clearly referable to _Fasciola Jacksoni_; that the parasites to which the natives of Hindostan apply the term “soorti” were evidently examples of _Ascaris lonchoptera_ (Diesing), previously called strongyles by Rudolphi; and that the worms which he called “masuri” were trematodes new to science. I named the species _Amphistoma Hawkesii_, in honor of the donor. The bottle contained as many as forty-nine specimens. I may here remark that I have made inquiries of the keepers of the elephants at the Zoological Gardens as to whether they have ever seen entozoa that were passed by the animals under their care. They replied in the negative, the keeper of the African elephants (Scott) having made frequent inspection of the fæces. I was the more anxious to secure information on this point since, during my frequent visits to the menagerie, I had observed that the African elephants were in the habit of swallowing large quantities of mud and dirt from small hollows in the ground near the great water-tanks in which they bathe. Prof. Garrod (who had dissected three elephants) also assures me that there has been no trace of an entozoon in any of the Indian elephants examined by him. In one dissected at Edinburgh the same negative result was obtained. From the facts at present in my possession, I conclude that the habit of earth-eating, displayed alike by Indian and African elephants (and, as stated in my account of the equine parasites, shared by horses), is not necessarily due to the presence of parasites. I apprehend rather, that it is resorted to by these animals under any circumstances of intestinal irritation, whether created by entozoa or other foreign agents. The notion of the elephant’s intelligent self-cure by eating earth is a very old fable. Captain Forsyth, as quoted by Mr Fleming, alludes to it in his ‘Highlands of Central India,’ and I find the same ideas recorded by Williamson and Howitt. Forsyth says:--“Elephants are very liable to intestinal worms. They generally cure themselves by swallowing from ten to twenty pounds of earth.” Captain Williamson says:--“They are much troubled with worms, for the cure of which the elephant eats earth. If the dung be inspected there will be seen an amazing number of moving objects, which much resemble pieces of chewed sugar-cane.” Some excellent practical remarks are added, testifying to the value of the native remedy called _Kallah-nimok_, or _bit-noben_, which is a saline purgative. In Lieut. Ouchterlony’s essay (quoted below) no allusion is made to the subject of worms.

General Hawkes afterwards supplied me with further information. In a letter from Secunderabad, dated July 30th, 1875, he says:--“As regards the liver-fluke (_F. Jacksoni_), it appears from your treatise to have been first observed in 1847. The only other published notice that I have been able to find of it is contained in a letter to a newspaper, dated ‘Rangoon, 16th July, 1867,’ and is signed ‘R. B.’ In this letter the unusual mortality of seven elephants in about fifteen days is attributed to the presence of this liver-fluke, the two other parasites (_Amphistoma_ and _Ascaris lonchoptera_) being also present in the intestines.” “Now (continues General Hawkes), in every case at which I was present _flukes were found in greater or less numbers_ in the gall-ducts of the liver, and the _Amphistoma_ was also as constantly present in the intestines, the soorti (_Ascaris lonchoptera_), contrary to the general experience of the elephant attendants, being less frequently met with, though from its color and slender shape it is not so easily detected among the huge mass of fæces as the larger _Amphistoma_.” Speaking of the amphistoma General Hawkes says:--“This internal parasite is well known to all who possess elephants. It is alluded to by Dr Gilchrist in his treatise on the ‘Diseases of Elephants,’ first published in 1841, but he merely mentioned it under its local name, _masuri_, and made no attempt either to describe it scientifically or to ascertain its place in the natural system. As far as my experience goes it is only found in the intestines. These parasites appear to be very generally present in the elephant. When their numbers are few the ‘host’ is probably not much inconvenienced, but when present in any great quantity they undoubtedly cause much irritation. When this is felt, the animal, as before remarked, instinctively resorts to a simple and effectual remedy. He eats a quantity of earth, which purges him thoroughly and expels the amphistoma. The mahawats are of opinion that whilst the elephant is eating earth to relieve himself of the pests the daily allowance of rice should be scrupulously withheld; and they say that if the rice, which is given uncooked, is eaten by the animal under these circumstances, excessive purgation is induced, which frequently results in death. How far this opinion is founded on fact I am unable to say, but the mahawat’s name for this disease means ‘fasting,’ and bears testimony to the generally received notion of the necessity of withholding the rice when the animal is eating earth.”

When describing the parasites of the horse (p. 358), I spoke of Collins’ amphistome from that animal, but in the letter addressed to me from Simla, 22nd March, 1875, Mr. Collins made no allusion to the earth-eating habit. He wrote:--“I forward you by this mail parasites found in the colon of a horse that died, a subject of fever peculiar to this country. There were _about a thousand_ of the parasites, and nearly the whole of them were situated close to the cæcum, and were loose in the gut. Not having seen parasites at all similar to these, I have forwarded them for identification. They were of a brick-red color when first obtained.” These explicit statements by Mr Collins are interesting from many points of view. One has only to place his specimens side by side with those from the elephant in order to satisfy one’s self that the two forms are distinct. For the reasons already stated I provisionally called the worm _Amphistoma Collinsii_. It is probable that other veterinary surgeons have encountered this entozoon in India; but, unless they can point to some published account of the fact, Mr Collins is entitled to be considered as its discoverer. Doubtless many other European residents in India, Ceylon, and Burmah, must, like Dr Gilchrist, be well acquainted with the _masuri_ as such, though unaware of their zoological position.

In a record of the post-mortem examination of one of the victims of the Secunderabad epizoöty, the veterinary surgeon said:--“No doubt disease of the lungs and subacute inflammation of the bowels were the immediate cause of death, but the large number of flukes in the liver and the intestinal parasites (_i. e._ the amphistomes) account in a great measure for some of the symptoms shown, and these symptoms accord in many respects with those shown in elephants that died in Burmah during the epizoöty (rot) in 1867, as recorded by R. B., notably, refusal of food, standing with mouth open, restlessness, and puffiness about the head and shoulders. The liver parasite is no doubt the same referred to by R. B., and is that termed by Dr Cobbold _Fasciola Jacksoni_.” In reference to a later case the same officer remarks:--“I carried out the post-mortem examination with special reference to inquiry as to the probability of the mortality amongst elephants at this station being of parasitic origin. This was suggested to me by the former case. The post-mortem appearances differed in every respect. There were flukes in the liver, but in no great quantity, and the structure of the liver was sound. Although not assisted by this case in attributing the mortality to parasitic origin, I am strengthened in my opinion that the death of the previous elephant was due to disease caused by the presence of the liver fluke.” This report, by Mr W. S. Adams, is to some extent in harmony with later information. An epizoötic outbreak amongst elephants has occurred in England, at Sanger’s Circus, and I had opportunity to examine one of the dead animals. In my own opinion, and in that of Mr F. Smith, the veterinary surgeon who attended the animals professionally, the disease was due to parasites. I obtained large quantities of _Amphistoma Hawkesii_ from the intestinal canal, and also other worms. The death of one of the elephants was made the subject of litigation, when, as might be expected, great diversity of opinion as to the cause of the fatal issue prevailed.

Mr Smith, an old pupil of mine, regarding the amphistomes and strongyles as the cause of death, wrote to the effect that “some of the worms were found between the coats of the intestine, and others on the free surface of the gut, whilst the excretory ducts of some of the glands were found blocked with them.” The animal examined by myself on the 24th of August, 1876, yielded numerous examples of _Amphistoma Hawkesii_, _Ascaris lonchoptera_, and _Dochmius Sangeri_, the last species being so named by me after the owner of the circus who lost the herd of elephants by the epizoöty. The male _Dochmii_ measured 5/8 and the females 3/4 of an inch in length. Here I must reluctantly quit the helminths of elephants, adding only an expression of surprise that Dr Max Schmidt should have had so little to say concerning them in his otherwise instructive memoir on ‘The Diseases of Pachyderms’ (quoted below).

I have but a few words to offer respecting the ectozoa. A species of mite has been described whose generic position appears doubtful. I allude to _Homopus elephantis_ of Fürstenberg, or _Symbiotes elephantis_ of Gerlach. According to Mégnin it is a _nymphe adventive_ or _hypope_ of a variety of _Tyroglyphus siro_. This acarus is abundant in old forage. Another ectozoon is _Hæmatomyzus elephantis_. It differs from the lice proper in many respects, but, according to Piaget, the reproductive organs resemble those of _Hæmatopinus_. In ‘Science Gossip’ for June, 1871, Mr H. C. Richter describes “a new form of parasite,” which is called _Idolocoris elephantis_. The insect, which was one line in length, was found upon an elephant in Ceylon. According to Walker it not only constituted the type of a new genus, but of an altogether new family of the Hemiptera Heteroptera, coming very near to the bed-bugs (_Acanthidæ_). It is a huge sucking louse. From the discussion which followed, it seems that the parasite had several times been seen before, and was none other than E. Piaget’s _Hæmatomyzus elephantis_. Excellent figures accompany Richter’s and Piaget’s descriptions. Notwithstanding Piaget’s explanation, I think the specific name, _longirostris_, would have been a more appropriate appellation.

BIBLIOGRAPHY (No. 51).--(Anonymous), “Diseased Elephants,” see ‘Lancet,’ Sept. 2, 1876; also “Report of the Case at Law (Jamrach _v._ Sanger),” given in the ‘Veterinarian,’ Dec., 1877, p. 886.--_Cobbold, T. S._, “Description of a species of Trematode from the Indian Elephant, with remarks on its Affinities,” ‘Quart. Micros. Journ.,’ Jan., 1869; see also ‘Entozoa,’ supp., 1869, p. 80.--_Idem_, “On the Destruction of Elephants by Parasites, with remarks on two new species of Entozoa and on the so-called Earth-eating habits of Elephants and Horses in India,” ‘Veterinarian,’ Oct., 1875.--_Idem_, “Further Remarks on Parasites from the Horse and Elephant, with a notice of new Amphistomes from the Ox,” _ibid._, Nov., 1875.--_Diesing_ (l. c., in text).--_Fitz, R. H._, “Anatomy of _Fasciola Jacksoni_,” ‘Rep. of Boston Soc. Med. Sci.,’ in the ‘New York Med. Journ.,’ Nov., 1876.--_Fleming, G._, “The Diseases of Elephants” (chiefly from Captain Forsyth’s work on the ‘Highlands of Central India’), ‘Veterinarian,’ March, 1873, p. 181.--_Mégnin_, “Mém. sur les Hypopes,” in Robin’s ‘Journ. de l’Anat. et de la Physiol.,’ 1874 (_H. elephantis_), p. 248.--_Ouchterlony, J. W._, “An Essay on the Management of the Elephant, and its Treatment in ordinary Diseases,” ‘Rep. of Vet. Med. Assoc.,’ Nov., 1872, and pub. in ‘Veterinarian,’ Jan., 1873, p. 65.--_Piaget, E._, “Description d’un parasite de l’éléphant,” ‘Tijschrift voor Entomologie,’ 1869, p. 249.--_Richter, H. C._, “A new form of Parasite (_Idolocoris elephantis_),” ‘Science Gossip,’ 1871, pp. 131, 185, 211, 278.--_Schmidt, Max_, “Die Krankheiten der Dickhäuter,” ‘Deutsche Zeitschrift f. Thiermed. und vergleichende Pathologie,’ f. Nov., 1878, s. 360.--_Williamson, T._, ‘Oriental Field Sports,’ London, 1807, vol. i, p. 138.

The parasites of the _Rhinoceridæ_ have been even less studied than those of elephants. In 1856 Prof. Peters described a tapeworm from Bruce’s rhinoceros (_R. Africanus_), which he named _Tænia gigantea_. In 1870 Dr Murie, under the provisional name of _T. magna_, published a description of the strobile of the same cestode from an Indian rhinoceros (_R. unicornis_). From a total misconception of the character of the proglottides, Murie was led to suppose that the segments of the strobile were very deep as well as broad; whereas the proglottids are remarkably narrow, thus partaking of the characters of the Tæniæ of the larger herbivora in general. In a subsequent paper Peters pointed out these errors. Murie had, in fact, rolled several segments into one. In 1877 Professor Garrod encountered the same cestode in _Rhinoceros sondaicus_, and, following Peters’ example, separated it from the Tæniæ proper (_Plagiotænia gigantea_). The idea of generically separating tapeworms possessing a more or less striking breadth of strobile is not one which commends itself to my view, seeing that many of the tapeworms of herbivora closely resemble the rhinoscerine cestodes in this respect. As Diesing hints, this tapeworm comes near to _T. perfoliata_, but Garrod’s and Peters’ figures both show that _Plagiotænia_ wants the neck-lobes. The presence of cephalic appendages may be regarded as generically distinctive, but it does not appear that Blanchard separated the perfoliate tapeworm of the horse from the Tæniæ proper on this ground. Therefore, in my account of the equine tapeworms, I have not adopted his genus _Anoplocephala_. I may remark, in passing, that if the distinctions, as between armed and unarmed, or between proboscis-bearing (_Rhynchotæniada_) and non-proboscis-bearing tapeworms (_Arhynchotæniada_), are to be maintained, they should be expressive of divisional or subordinate value. Dr Weinland’s arrangement, having reference to the thick- and thin-shelled ova (Sclero- and Malaco-leptidota), is, perhaps, preferable. The whole subject of classification requires revision, but it should be undertaken by some helminthologists practically acquainted with a large number of cestode types. As Garrod has well observed, _Plagiotænia_ enjoys a wide geographical distribution, infesting alike Indian and African hosts. Prof. Garrod, I observe, speaks of the _head_ of the mature tapeworm as the _scolex_--an extension of the meaning of a term not usually recognised. In this, however, he only follows Peters’ unfortunate example.

The wide distribution enjoyed by Peters’ Plagiotænia is probably equalled by that of the rhinocerine stomach-bot (_Gastrophilus rhinocerontis_, Owen). This parasite was originally described in 1840, and since that time it has been frequently encountered both in India and Africa. To Mr Spooner Hart, of Calcutta, I am indebted for a large number of specimens; their size exceeding that of any other bots that have come under my notice. Probably this parasite infests the stomach of rhinoceroses generally; at all events, it occurs in _R. unicornis_, _R. bicornis_, and _R. simus_. At present the imago is unknown. The longest larvæ in my possession measure 1-1/8″, but Brauer records specimens up to 35 mm. in length by 10 mm. in thickness. In African hosts M. Delegorgue found these parasites in prodigious numbers.

BIBLIOGRAPHY (No. 52).--_Brauer_, “Bot of the Rhinoceros,” ‘Monogr. der Œstr.,’ 1863, s. 92.--_Cobbold_, “Note on Parasites presented by Messrs Danford, Hart, and others,” ‘Veterinarian,’ 1875, p. 513.--_Coquerel_ and _Sallé_, in ‘Ann. Soc. Entom. de France,’ 1862 (quoted by Brauer).--_Delegorgue_, ‘Voyage dans l’Afrique’ (quoted by Brauer).--_Garrod_, “On the Tænia of the Rhinoceros of the Sunderbunds (_Plag. gig._, Peters),” ‘Proc. Zool. Soc.,’ Nov. 20, 1877, p. 788.--_Hope_, in ‘Trans. Entom. Soc.,’ 1840, p. 259.--_Joly, M. N._, “Recherches Zool. (&c.) sur les Œstrides (&c.),” in ‘Ann. des Sciences (&c.) de Lyon,’ 1846 (quoted by Brauer).--_Murie, J._, “On a probably new species of Tænia (_T. magna?_) from the Rhinoceros,” ‘Proc. Zool. Soc.,’ 1870, p. 608.--_Peters, W._, “Note on the Tænia from the Rhinoceros, lately described by Dr J. Murie,” ‘Proc. Zool. Soc.,’ 1871, p. 146.

Very little has been written respecting the parasites of the _Hippopotamidæ_ and _Tapiridæ_. I think it was Livingstone who first drew attention to the fact that the river-horse or sea-cow is much infested by tapeworms, but I have not seen any published description of the worm. Dr. Murie, during his sojourn in Egypt, found a solitary bot embedded in the soft parts surrounding the eye, and judging from his figure the species is new to science. Provisionally I speak of it as the _Hypoderma Muriei_. In the paper (quoted below) Murie appends a list of all the animals in which bots have been found. Though chiefly taken from Brauer, it is useful and tolerably complete. So far as I am aware no cestodes have been described as infesting tapirs; nevertheless, at least five other kinds of helminth have been found in _Tapirus Americanus_. Of these, two are flukes (_Amphistoma asperum_ and _A. pyriforme_), and three are nematodes (_Sclerostoma monostechum_, _Spiroptera mediospiralis_, and _Sp. chrysoptera_). The three species first named occupy the cæcum, whilst the others are found in the stomach. According to Molin’s description, both species occupy tuberous excrescences of the mucous membrane, thus reminding us of the similar habit enjoyed by _Sp. megastoma_ in the horse. The _Sp. chrysoptera_ is a comparatively large species, the males measuring an inch, and the females as much as an inch and a half in length. Both of the spiropteras were obtained from tapirs by the indefatigable Natterer, _Sp. mediospiralis_ being also procured by him from the aguti. If I have read Molin correctly, as many as thirty-four examples of _S. mediospiralis_ were taken from a single excrescence in the stomach of the tapir. Upwards of a hundred specimens were procured, collectively, from three similar stomach-excrescences in _Dasyprocta aguti_. These, and the other tapirine parasites above mentioned, were originally discovered in Brazil.

BIBLIOGRAPHY (No. 53).--_Diesing_, “Neue Gattungen von Binnenwürmen nebst einem Nachtrage zur Monographie der Amphistomen,” in ‘Annalen d. Wien. Museums,’ Feb., 1839, s. 236.--_Idem_, ‘Systema,’ Bd. ii, s. 306.--_Molin_, “Una monografia del genere Spiroptera,” in ‘Sitzungsb. der math.-naturw. Cl. d. k. Akad. d. Wissensch.,’ Bd. xxxviii, s. 1001, 1859.--_Murie_, “On a larval Œstrus found in the Hippopotamus,” ‘Proc. Zool. Soc.,’ 1870, p. 78.

The osculant position of the anisodactyle pachyderms (_Hyracidæ_), formerly classed as rodents, renders it desirable that their parasites should be briefly noticed in this place. Probably these animals, zoologically speaking, come nearest to the rhinoceroses, but Prof. Owen showed that, anatomically, they possessed marked affinities with the sloths. The klipdas or dasse (_Hyrax capensis_) is infested by a tapeworm, of which hitherto the proglottides only appear to have been seen (_Tænia hyracis_, Pallas). Under the name of _Cœnurus serialis_ a larval cestode has been described by Gervais, the same parasite being called _Arhynchotænia critica_ by Pagenstecher (“Zur Naturgeschichte der Cestoden,” in ‘Sieb. u. Köll. Zeitschrift’). A variety of nematodes have also been observed in the Cape hyrax. Of these, the so-called _Physaloptera spirula_ is classed as doubtful by Molin and Diesing. Hemprich and Ehrenberg furnished brief descriptions of four other nematodes. Two of these worms were placed in the genus Oxyuris (_O. pugio_ and _O. flavellum_), and the other two in the new genus Crossophorus, which they formed for their reception (_C. collaris_ and _C. tentaculatus_). The whole of these nematoids were obtained either from the cæcum or large intestine.

An able article in the ‘Natural History Review’ for July 1865, attributed to Professor Huxley, expressed very clearly the popular notion as to the great danger of the flesh of swine considered as a source of human parasites. No doubt the filthy pachyderms in question (_Suidæ_) are much infested by helminths, some of which gain access to man, but swine are neither attacked by a greater variety of entozoa than other domesticated animals, nor are they so frequently a source of human tapeworms as cattle. In the article above quoted the following passage occurs:--“Of all animals, feral or domestic, the common pig is beyond all doubt the most fertile source of human entozoa; at least, of important parasites, _Trichina spiralis_ and the tapeworm would, there is good reason to believe, cease to infest us, did not this favorite quadruped act the part of a communicating medium.” This paragraph was evidently written under the impression that “the tapeworm” most commonly found in man was derived from the hog. So far back as 1864 I showed that this was an entire mistake.

Flukes are rare in swine; nevertheless, _Fasciola hepatica_ and _Distoma lanceolatum_ are occasionally present in the domestic hog, and the peccaries (_Dicotyles_) are infested by an Amphistome (_A. giganteum_). This large species, 3/4″ in length, formed the basis of an admirable account of the anatomy of this genus of worms which the learned Vienna helminthologist, Diesing, wrote before he was deprived of his eyesight. The merits of that respected systematist’s investigations have, I think, been much underrated, in consequence, no doubt, of the artificial character of his system of classification. For all that, his writings remain invaluable. Turning to the cestodes of swine, there is not, so far as I am aware, any evidence of the occurrence of sexually-mature tapeworms either in the hog or its allies; but the frequency of larval cestodes, known as measles (_Cysticercus telæ cellulosæ_), was well known to the early Jewish writers. In the first part of this work I devoted as much space as I could spare to the consideration of Cysticerci in general, and the pork-measle in particular; but an exhaustive knowledge of the subject in relation to hygiene can only be acquired by consulting the principal original memoirs (quoted in the Bibliographies Nos. 13 and 14). In a Westphalian ham, part of which was sent to me for examination, I calculated that each pound of the flesh must have contained upwards of 600 Cysticerci. I was informed by the donor, Dr Prior, that in spite of the disgusting state of the meat much of it had been eaten by the well-to-do family who purchased the ham. Cysticerci occasionally occupy the brain of the pig in considerable numbers. Florman recorded a case of this kind where their presence gave rise to vertigo in all respects resembling the gid ordinarily produced by _Cœnurus_ in the sheep. As regards the larger cestode larvæ, _Cysticercus tenuicollis_ and _Echinococcus veterinorum_ are of frequent occurrence. One not unfrequently encounters the former in the mesentery, whilst the liver of the hog is sometimes so crowded with hydatids that scarcely any of the glandular substance of the organ remains visible. It is surprising how little the infested bearers appear to be inconvenienced in such cases. In the winter of 1859, and in the autumn of 1860, I found large cystic entozoa in an African Wart-hog and in a Red River hog. These animals had died at the London Zoological Society’s Menagerie; and as the worms appeared to me at the time to be quite distinct from the ordinary slender-necked hydatid, they were named, respectively, _Cysticercus phacochæri æthiopici_ and _C. potamochæri penicillati_. The solitary example from the wart-hog was found in a cyst near the colon; whilst of the five large bladder-worms obtained from the Red River hog, one infested the liver and the other four were lodged in the folds of the mesentery. The caudal vesicle of the worm from the wart-hog measured 3-1/2″ in diameter, the vesicle of the other bladder-worm being much longer. A reference to the original figures will show that these forms are distinct. Swine are largely infested by nematodes. The best-known form is _Ascaris lumbricoides_, which Dujardin regarded as distinct (_A. suilla_). The hitherto disputed identity of this worm with the human lumbricoid being no longer questionable, the importance of the entozoon in relation to lumbricoid endemics must at once be obvious; I have already, however, dwelt upon this subject when treating of the human parasites. In like manner, the subject of the flesh-worm disease, which is due to _Trichina spiralis_, cannot be discussed in this place, as I have fully entered upon it in connection with trichinosis in the human subject. What may be the nature of the small threadworms found by Leidy in the extensor muscles of the hog I cannot say, but Diesing inferred that they might represent a distinct species (_Trichina affinis_). As regards the allied genus _Trichocephalus_, the common species infesting swine (_T. crenatus_), appears to be rarely absent. It not only infests the common domestic and wild hog, but the peccaries and wart-hogs. These entozoa are probably harmless to their bearers. In reference to them Krabbe says:--“When the eggs are expelled with the excrement and pass into water, then the embryos, after several months’ furlough, and there undergoing further development, are transferred to the swine’s intestinal canal.” If I rightly understand the paragraph (‘Husdyrenes Indvoldsorme,’ p. 28), Krabbe states that the embryos are still within their egg-coverings when infection takes place. The maw-worm of the hog is known as _Spiroptera strongylina_. It was described and figured by Gurlt. The males measure 1/2″ and the females 3/4″ in length. Specimens of this worm were supposed to have been found by Natterer in _Dicotyles albirostris_; but it seems that the worms in question represent a distinct species, if not an altogether new genus. In the year 1864 Professor Simonds placed in my hands a very singular nematode, to which I gave the binomial term _Simondsia paradoxa_. Numerous examples of this worm were found by Prof. Simonds occupying cysts within the walls of the stomach of a hog which had died at the London Zoological Society’s Menagerie. In my introductory treatise I wrote of it as follows:--“The worm in question has been regarded by Mr Simonds as a species of _Strongylus_, but I am inclined to think that its affinities will place it nearer to the genus _Spiroptera_. At present I have only examined the female, which is characterised by the possession of a multitude of large tentacle-like appendages surrounding the neck. These processes, by their aspect, remind one of the so-called branchial projections on the back of _Eolis_, but in this worm I believe them to be special folds formed for the lodgment of unusually developed uterine organs. The female worm is about 3/4″ in length.”

In the interval that has elapsed I have been unable to supply further particulars, and unfortunately the original drawings of the worm have been lost. The habits of the parasite remind us of _Spiroptera megastoma_ infesting the walls of the stomach of the horse. Not improbably this singular entozoon may turn out to be identical with Molin’s _Spiroptera sexalata_, and if so, it may correspond with _Spiroptera strongylina_. However, Diesing afterwards recognising, as I had done, the desirability of separating this last-named worm from the Spiropteræ proper, formed for it his new genus _Physocephalus_. He then called the worm _Physocephalus sexalatus_. If, as is probable, my _Simondsia_ and Diesing’s _Physocephalus_ are identical, the species found by Simonds ought to be recognised by the generic title which Diesing proposed. His genus was established about four years before I described my _Simondsia_. Diesing was evidently led up to the recognition of the generic distinction of the worm by Molin’s examination and description of the worm. As, in my original account of the worm found by Simonds, I spoke of numerous appendages to the neck, it is evident that further investigation is necessary to clear up the question of identity. According to Molin and Diesing the male _Spiroptera sexalata_ measures rather beyond 1/4″ and the female beyond 1/2″ in length. Neither Diesing nor Molin speak of Natterer’s worms as being found encysted. In fact they were free. Molin simply remarks:--“Io ne esaminai in oltre 6 esemplari maschi e 77 femine raccolti in parte dal muco che revestiva le pareti dello stomaco, ed in parte dal pasto contenuto nello stesso organo di un _Dicotyles albirostris_ femina ai 24 Aprile, 1826.” After all that has been said it may be that my _Simondsia paradoxa_ and Diesing’s _Physocephalus sexalata_ are quite distinct, and that like the large- and small-mouthed maw-worms of the horse (_Spiroptera megastoma_ and _S. microstoma_) they play a corresponding rôle. Before very long I hope to set this question definitively at rest.

Passing to the strongyloid nematodes one of the most remarkable and important species is _Stephanurus dentatus_. In the ‘Annalen des Wiener Museums’ for 1839 (s. 232) this worm was first described by Diesing, who employed the generic title as expressive of the crown-like figure of the tail of the male worm. Diesing wrote as follows:--“At Barra do Rio Negro, on the 24th of March, 1834, Natterer discovered this peculiar genus of worms occurring singly or several together in capsules situated amongst the layers of fat in a Chinese race of _Sus scrofa domestica_. The males measure from ten to thirteen lines long, the females from fifteen to eighteen lines, the former being scarcely a line in breadth at the middle of the body, whilst the latter are almost a line and a half in thickness. The curved body thickens towards the tail, is transversely annulated, and viewed with a penetrating lens is seen to be furnished with integumentary pores. The oral aperture opens widely. It is almost circular, and is supplied with six teeth at the margin. Two of these standing opposed to one another are larger and stronger than the rest. The tail of the male, when spread out evenly, is surrounded by a coronet of five lancet-shaped flaps; the combined flaps being connected together from base to apex by means of a delicate transparent membrane. The single spiculum situated at the extreme end of the tail projects slightly forward and is surrounded by three skittle-shaped bodies. The tail of the female is curved upon itself, rounded off, and drawn out at the extreme end into a straight beak-shaped point; whilst to both sides of the stumpy caudal extremity of the body short vesicular prominences are attached. The female reproductive outlet occurs at the commencement of the second half of the body. Thus, judging by its external characters this genus is most closely allied to _Strongylus_.” In reproducing Diesing’s description I have here rendered the translation somewhat more freely than in my previous record of the discovery given in ‘Nature’ (1871). The original description is supplemented by a brief account of the internal anatomy of the worm.

So far as I am aware no subsequent notice of this entozoon appeared until the year 1858, when Dr J. C. White gave some account of a “find” made in the United States. This re-discovery was reported in the sixth volume of the ‘Proceedings of the Boston Natural History Society.’ Dr White says:--“The worms were found in the leaf-yard of an apparently healthy hog, in the adipose tissue near the kidney. They occupied a space of the same about the size of a man’s fist and had burrowed through the mass in every direction, forming canals three or four millimètres in diameter, which terminated in cysts. On cutting open these cavities, which did not communicate with each other, they were found filled with pus, and in each were two worms, male and female.” Dr White expresses his opinion that the worms gained access to the tissues “by boring through the circulatory system while in the embryonic condition.” I think that Dr White deserves great credit for his correct diagnosis of the species, and all the more so because he was evidently not acquainted with Diesing’s original memoir. He expressly speaks of the “scanty descriptions” hitherto given of the worm. As Dr White had accurately determined the species in the presence of an American Scientific Society, it is remarkable that neither Verrill nor Fletcher should have identified the worm.

On the 10th of January, 1871, I received a letter from Prof. W. B. Fletcher, of Indianapolis, Indiana, U.S.A., and in it he announced that he had “found a worm” infesting the hog. The parasite was so abundant in swine that he obtained it in “nine out of ten hogs” which he had examined. Dr Fletcher sent me specimens of the worm for description and identification, when I at once recognised them as examples of Diesing’s _Stephanurus dentatus_. As Dr Fletcher’s first communication to myself was undated I do not know precisely when he first encountered the worm, but it was in 1870. In that same year Prof. Verrill received specimens of the worm. He says that they were received from Dr J. C. White. Failing to identify the parasites as _Stephanuri_, Verrill (making no allusion to the ‘Proceedings of the Boston Society’) not unnaturally supposed he had to deal with an entozoon that was new to science. Accordingly he immediately described and figured the worm under the combined title of _Sclerostoma pinguicola_. If these data are correctly given, the re-discovery of the worm in America was due to Dr J. C. White; its identity with _Stephanurus_ being subsequently acknowledged by Diesing, and afterwards, quite independently, by myself. I gather this partly from Diesing’s ‘Kleine helminthologische Mittheilungen’ (s. 281), published as a supplement to his ‘Revision der Nematoden’ (1860-61). Until quite recently Diesing’s recognition of the identity of White’s parasites with Stephanuri was unknown in America. My conclusions arose from an examination of the actual specimens, whereas Diesing was entirely guided by White’s description. In this connection, moreover, a still more interesting re-discovery remained to be recorded. The original announcement which I made in the ‘British Medical Journal’ for January 14th, 1871, was followed by another in the same periodical for September, 1871. As stated in my second letter and repeated in my notice of Krabbe’s memoir on “Parasites” (‘London Medical Record,’ April 2, 1873), the President of the London Microscopical Society (through Mr Slack, who was at that time the secretary) forwarded to me a box of microscopic slides received by the Society from Australia. The slides displayed parasites of various kinds. Having been requested to identify the parasites I had the good fortune to recognise amongst them characteristic examples of _Stephanurus dentatus_. Thus was first made known the fact that this singular genus was not confined in its geographical distribution to the two American continents, but that it extended to Australia. The order of the principal “finds” and descriptions may therefore be thus restated. Natterer discovered the worm in Brazil in 1834. Diesing described it in 1839. Dr J. C. White re-discovered and identified the worm in 1858. It was subsequently found by Dr N. Cressy and by Dr Fletcher. These three observers all encountered the parasite in the United States (1858-70). Prof. Verrill re-described the worm as new to science in September, 1870. Diesing confirmed White’s diagnosis in 1860. I identified the worm from Fletcher’s “find” in 1871. Dr Morris supposed he had discovered a new entozoon in Australia in July, 1871. The Australian worms were identified by me as examples of _Stephanurus dentatus_ in October, 1871.

The importance of _Stephanurus_ in relation to porcine epizoöty and the supply of animal food cannot be ignored. As remarked in my communication to ‘Nature,’ it must be quite obvious that so large a parasite, when present in the hog in any considerable numbers, would give rise to serious disease, even if it were not productive of fatal results to the bearer. In one of his numerous communications to myself, Prof. W. B. Fletcher writes as follows:--“It is my opinion that this parasite is the cause, in some way, of the hog cholera, which has created such sad havoc within the past ten years over the pork-producing parts of America. One farmer told me, a few days ago, that within a month his loss alone from this cause was over one hundred head; and sometimes, in one neighbourhood, in a few days’ time, thousands have perished, although this season is not a cholera year, as our farmers say. I advised one farmer to burn or bury the dead animals, but he informed me that he believed that fewer hogs die of the disease after eating the dead animals than those kept from them. Unfortunately, in this State there is no law guarding the spread of disease, neither is there any reward of reputation or gain for pursuing any investigation that would bring pork and beef packers into disrepute. I myself could not get a pig’s kidney or beef’s liver in our city market, because I made investigations in some Texas cattle (being cut up in our market), which damaged their sale a few years ago.” In a third letter Dr Fletcher tells me that greater facilities for examining the carcases of hogs had since been accorded him through the liberality of a Liverpool firm of pork-packers, who had already killed 75,000 hogs during the summer season, _i.e._ up to the date of the first week in July. In hot weather the slaughtering is conducted in ice-houses. Prof. Fletcher’s views receive confirmation from the statements made by Dr Morris, who speaks of the pigs as dying from some mysterious disease, and thinks that the worms may be the cause of the porcine mortality. Writing to the President of the London Microscopical Society from Sydney (July 12th, 1871), Dr Morris says:--“It is just possible that some pigs may survive the irritation such a swarm of young worms must set up; others, again, may die from peritonitis, hence the sudden deaths amongst the pigs.” I think Dr Morris’ view is perfectly correct, but whether it be so or not, it is (as observed by me in ‘Nature’) interesting to notice the remarkable correspondency of the conclusions arrived at by Drs Fletcher and Morris independently. It will probably not be difficult to ascertain hereafter whether or not the maladies respectively termed “hog cholera” and “mysterious disease” are one and the same disorder, but whatever happens in this respect, it is now quite clear that this parasite, hitherto little regarded, and for many years past persistently overlooked, is extraordinarily prevalent in the United States, and, perhaps, equally so in Australia; it being further evident that its presence in the flesh of swine is capable of producing both disease and death. The statement of the worthy American farmer that the swallowing of infested flesh by pigs does not necessarily involve the pig-eating hog in a bad attack of the so-called “cholera disease” requires to be further tested, and it also remains to be proven whether or not the _Stephanurus_ be capable of passing through all its developmental changes from the egg to the adult form within the body of the bearer without having at some time or other gained access to the outer world. The comparatively large size of the ova, which I find to be about 1/105″, or more than four times the size of Trichina-eggs, is not without significance, but as yet we are entirely unacquainted with the larvæ of _Stephanurus_. If no intermediary bearers are necessary to its development, we ought not to have to wait long for a complete record of the life-history of _Stephanurus dentatus_. In conclusion, I will only further remark that since thousands of hogs are infested by this entozoon the subject is worth further investigation. I believe that Prof. Fletcher brought the matter under the notice of the United States National Swine Breeder’s Association, which met at Indianapolis in November, 1872, but with what success I have been unable to learn. The wealthy agricultural societies of Great Britain pay little or no regard to the subject of parasites, although thousands of valuable animals annually perish from the injurious action of entozoa.

Of the remaining nematodes infesting swine I must particularly mention _Sclerostoma_ (_Strongylus_) _dentatum_ and _Strongylus paradoxus_, the last named being generally regarded as identical with Dujardin’s _S. elongatus_. The first of these two parasites infests the small intestines, the male and female worms alike measuring about 1/2″ in length. The females are sometimes a trifle longer. The _Sclerostoma dentatum_ is an abundant parasite, infesting all varieties of swine and also peccaries; but it is apparently incapable of serious injury to the bearer. Schneider selected the male _S. dentatum_ for classificatory purposes. In this worm the arrangement of the rays of the hood is simple, forming a good central type. Dr D. V. Dean, in his excellent report of St Louis Board of Health (1874), speaks of _Strongylus dentatus_ as if it were the same entozoon as _Stephanurus_. The confusion of nomenclature would have been avoided if Diesing had called the renal worm _Stephanurus Nattereri_. I hope this title will yet be adopted to prevent future mistakes. The lung-worm (_S. paradoxus_) is by no means harmless, being a frequent cause of fatal husk in young pigs. It is a viviparous worm, the females acquiring a length of 1-1/2″, whilst the males rarely exceed 3/4″. Under the title _Gongylonema pulchrum_, Molin has noticed yet another filariform nematode infesting the wild hog; and, lastly, the lamented Russian traveller, Fedschenko, has published a full description of a new species of Gnathostoma (_G. hispidum_), which infests the coats of the stomach alike of the wild and domestic hog. One of the most interesting parasites of swine is the large acanthocephalous entozoon (_Echinorhynchus gigas_). It infests the small intestines both of the wild and domesticated hog, and it was also obtained by Natterer from the collared peccary of Tayazou. Common as the great Echinorhynchus is in the United States (and it is scarcely less so on the Continent) I believe that few, if any, of the museums in the United Kingdom of Great Britain contain this large entozoon. It is a curious fact that it does not exist in the Hunterian Collection, where, however, there is displayed a very fine set of acanthocephalous parasites from whales. When in the year 1865 I mounted, with my own hands, 200 preparations of entozoa for the Museum of the Royal College of Surgeons, I had not so much as seen a specimen of this worm. Much scientific interest attaches to this parasite from the fact that Schneider discovered that the embryos of _E. gigas_ take up their residence in the larvæ of the cockchafer (_Melolontha vulgaris_). He thinks it identical with the _Echinorhynchus hominis_ of Lambl. Leuckart disputes this identity, and compares Lambl’s worm with the _Echinorhynchus angustatus_ of our fresh-water fishes. The _E. spirula_ of certain Brazilian monkeys and of the Barbary ape bears a strong resemblance to the species from the hog. On the strength of Lambl’s case--and it is the only genuine instance of the kind on record--Prof. Leuckart devotes no less than 125 pages of his great work to the consideration of the structure and development of the thorn-headed intestinal worms. This worm demands especial attention. Speaking of the hog’s Echinorhynchus, Prof. Verrill, in his ‘Connecticut Report,’ says that “sometimes the intestine of a hog is found perforated by so many holes that it cannot be used in the manufacture of sausages.” From Mr George Wilkins I learn that the pig-slaughterers of our English metropolis are well acquainted with these perforations, which are sometimes so numerous that the gut looks as if it had been “riddled” with swan-shot. No wonder that diseased hogs, afflicted with these formidable parasites, go about, as Verrill expresses it, “continually squealing and grunting, especially in the morning.” That they are also “cross and morose, and given to biting and snarling at their companions,” is by no means astonishing. “In severe cases,” remarks Verrill, “hogs afflicted with this parasite are weak in the loins, and have the membranes in the corners of the eyes swollen, watery, and lighter colored than usual.” It is some comfort to know that Lambl’s human case is unique, and that so long as people abstain from eating cockchafer larvæ they are not likely to be infested by _Echinorhynchus gigas_. In the first book of this work I have given my reasons for not regarding Welch’s “encysted _Echinorhynchus_ in man” as a genuine example of this curious genus of entozoa.

The external parasites of swine are not so numerous as might be expected from the habits of their hosts. The most common ectozoon is the hog louse (_Hæmatopinus suis_). This disgusting little insect is about 1/8″ in length. Almost equally common is the hog mite. Though hitherto considered as a distinct species (_Sarcoptes suis_, Gurlt), it is regarded by Mégnin as a mere variety of _Sarcoptes scabiei_. As Gerlach and others have remarked, it is readily transmissible to man. The _Sarcoptes squammiferus_, of Fürstenburg, is only another name for this variety of _S. scabiei_. Speaking of this scab-insect Mégnin says:--“This parasite was first encountered by Spinola and Gurlt, and afterwards by Müller.” He then adds:--“A Ceylon wild boar died at the menagerie of the Museum of Paris of a chronic affection of the skin which had transformed its integument into a vast _lichen_.” Lastly, as regards the protozoal parasites I can only remark that the psorosperms (spoken of as Rainey’s corpuscles or as Miescher’s utricles) are often very abundant in the flesh of otherwise perfectly healthy swine. Having dwelt upon the character of such organisms in the first moiety of this work, I will only remark that the full significance of these singular bodies yet remains to be determined. Rainey’s notion that they represented early stages of cysticercal growth is altogether untenable. According to Behrens, as quoted by Davaine, psorosperms are especially abundant in the flesh of swine which have recovered from the disease called _mal rouge_. On the subject generally, the writings of Rivolta, Waldenburg, Eimer, and Siedamagrotsky are especially trustworthy. Full references to these and other authorities are given in the synopsis of the 2nd edition of Davaine’s well-known treatise.

BIBLIOGRAPHY (No. 54).--(Anonymous), “On Parasitic Maladies, especially Measles, of the Pig,” from ‘Scottish Farmer and Horticulturist,’ in ‘Edin. Vet. Rev.,’ p. 688, 1861.--_Ballard, E._, “On Diseased Meat, and what to observe in cases of suspected Poisoning by Meat or Sausages (infected with Entozoa, &c.),” ‘Med. Times and Gaz.,’ Jan., 1864.--_Bowditch, H. J._, “Raw Pork as an Aliment (without reference to the question of Entozoa.--T. S. C.),” ‘Boston Med. and Surg. Journ.,’ vol. lv, 1857; see also ‘Comments,’ vol. lvi, pp. 23 and 69, 1857.--_Cobbold_, “On the Discovery of Stephanurus in the United States and in Australia,” in ‘Nature,’ Oct. 21, 1871, p. 508, and in ‘Brit. Med. Journ.,’ Jan. and Sept., 1871; also in the ‘Monthly Micros. Journ.,’ Nov., 1871.--_Idem_, “Internal Parasites of the Hog,” in ‘Manual,’ chap. xii.--_Idem_, “On Cystic Entozoa from the Wart-Hog and Red River Hog,” ‘Proc. Zool. Soc.,’ 1861.--_Idem_, “On Simondsia,” ‘Entoz.,’ p. 79.--_Idem_, “Note on Worms in the Lungs of a Pig,” in the ‘Field’ for Jan. 9, 1864.--_Idem_ (in relation to Cysticerci or Measles, see Bibl. Nos. 13 and 14, and, for remarks on psorosperms, Bibl. No. 41).--_Cressy, N._, ‘On the Diseases of Domestic Animals in Connecticut (2nd and 3rd Ann. Reports),’ Hartford, U.S., 1873-74.--_Idem_, “The demands of Agriculture on Veterinary Science,” in ‘Rep. of the Mass. Board of Agric.,’ 1874.--_Idem_, ‘Find of Sclerostoma’ (quoted by Verrill).--_Crisp_, “Note on Hydatid Cysts in the Abdominal Cavity of various Hogs,” ‘Path. Soc. Trans.,’ 1863.--_Dardel_ (see Bibl. No. 14).--_Davaine_, “Ladrarie chez le porc,” in his ‘Traité,’ 2ème edit., p. 668 (see also the writings of Delpech, Guardia, and especially Reynal, quoted at p. 674).--_Dean, D. V._, “On Meats and Parasites,” in ‘Seventh Ann. Rep. of Board of Health of the City of St Louis,’ 1874, p. 58 _et seq._--_Diesing_, ‘On Stephanurus’ (quoted in text above).--_Dupuy_, “Hydatid in a Pig,” from ‘Journ. Théorique et Prat.,’ in the ‘Veterinarian,’ vol. iv, 1831, p. 285.--_Fedschenko_, ‘Description of new Species of Tetrastemma, Prorhynchus, and Gnathostoma’ (in the Russian language), Moscow, 1872.--_Fleming, A._, “Measly Pork as Food for Man,” ‘Edin. Vet. Rev.,’ vol. i, p. 485, 1858-59.--_Idem_, “On the Measle of the Pig, and on the Wholesomeness, as Food for Man, of Measly Pork,” ‘Dubl. Quart. Journ.,’ 1857.--_Fletcher_ (quoted in text above).--_Florman_ (quoted by Rudolphi, ‘Synops.,’ p. 620, 1819; and by Davaine, l. c., p. 723, 1878), in ‘Vetensk. Acad. Nya Handlingar,’ 1810, pp. 179-182.--_Gairdner, W. T._, “Case of Tapeworm occurring in connection with the Eating of Raw Pork,” ‘Edin. Month. Journ.,’ 1856, and in the ‘Veterinarian,’ vol. xxix, p. 228, 1856.--_Gamgee, J._, “On Diseased Meat,” ‘Pop. Science Rev.,’ Jan., 1861.--_Gordon_, “On Tapeworm from Unwholesome Food,” ‘Med. Gaz.,’ 1857.--_Gross, S. D._, “Note on the frequency of Acephalocysts in Swine at Cincinnati,” in his ‘Elements of Path. Anat.,’ p. 118, 1845.--_Gurlt, E. F._, ‘Lehrbuch der path. Anat. der Haus-Saügethiere,’ 1831, s. 46, 51, 142, 385.--_Heller_ (see Bibl. No. 13).--_Krabbe_, ‘Husdyrenes Indvoldsorme’ (l. c., in text; see also review in ‘Lond. Med. Rec.,’ April 2, 1872, p. 206).--_Leidy_, “Note on _Trichina spiralis_ from the Pig,” from ‘Rep. Acad. Philad.,’ in ‘Ann. Nat. Hist.,’ vol. xix, 1847.--_Leuckart_ (see Bibl. No. 13).--_Lewis_ (Bibl. No. 13).--_Martin, J._, “Case of Hydatids in the Liver of a Sow,” ‘Trans. Vet. Assoc.,’ pp. 330 and 364, 1842-43.--_Mégnin_ (Bibl. No. 14).--_Molin_, ‘Una Monog. del Gen. Spiroptera,’ Wien, 1860.--_Morris_, “Report on Australian Parasites,” ‘Month. Microsc. Journ.,’ Nov., 1871.--_Percy, S. R._, “On Diseased Meat in relation to Public Health (Prize Essay),” ‘New York Med. Journ.,’ 1866.--_Idem_, “On the Food of Cities (an Address),” ‘New York,’ 1864.--_Perroncito_ (Bibl. No. 13).--_Putz_ (Bibl. No. 14).--_Rainey_ (Bibl. No. 14).--_Rigetti_ (Bibl. No. 14).--_Sawer, A._, “Trichina,” in ‘Bost. Med. and Surg. Journ.,’ 1865, p. 16.--_Schmidt, Max_ (see Bibl. No. 51).--_Tartivel_ (Bibl. No. 14).--_Thudichum_ (Bibl. No. 13).--_Tommasi_ (Bibl. No. 13).--_Verrill_, “On Sclerostoma,” ‘Amer. Journ. Sci. and Arts,’ Sept., 1870.--_Idem_, “The External and Internal Parasites of Man and Domestic Animals,” from ‘Rep. of the Conn. Board of Agriculture,’ 1870, p. 109.--_Walker_ (see Bibl. No. 20, _o_).--_Wheeler, E. G._, “Worms in the Lungs of Swine,” ‘Bost. Med. and Surg. Journ.,’ 1841.--_White, J. C._, “On Stephanurus,” ‘Proc. Bost. Nat. Hist. Soc.,’ vol. vi, p. 428, 1858.