CHAPTER VI.

The Mineral and Geological Kingdoms.

The structure of rocks and the formation of crystals will be found to furnish an endless supply of instructive material for the microscope. In sciences of pure observation, as those of mineralogy and geology, the facts to be observed are of several different kinds, and where so many observers are at work all over the world, constant progress will necessarily be made, as well as continued correction required from change and improvement in the methods of observation. It would be impossible to give even a slight sketch of what has been done in the two departments of nature referred to during the past few years. Mineralogical and geological research have derived very great advantage from having been assigned to professional teaching. But, as Professor Bonney reminds us, the progress made in geological work in particular, has been directly due to the revelations of the microscope. It called forth an instrument of special construction for the purpose, the petrological microscope (Fig. 79), well equipped with Nicol’s prisms, and numerous other appliances demanded for the important investigations.

“Upon the history of the two main groups of rocks the microscope has thrown much light. For the igneous rocks it has simplified their classification and determined their mutual relations; while for the rudimentary group, it has shown the true nature of their constituents, and pointed out the sources from which they were derived. But it is in helping to elucidate the problem of the metamorphic rocks, of which much less was known, that the microscope has been of the most service. It has likewise greatly assisted in the attempt to determine the history and mutual relation of these rocks. One of the most important results within the last few years has been the demonstration that without exception these crystallin schists are very old, all probably older than the first rocks in which traces of life have been found. The conclusion arrived at, is that “the environment necessary for changing an ordinary sediment into a crystalline schist existed generally only in the earliest ages, and but very rarely and locally, if ever, since palæozoic time began.”

The crystalline schists then are the relics still preserved to us of the early days of the earth’s history, when the temperature near the surface was still high. Since that time the zone for marked mineralogical changes has been continually sinking, until at the present day it has reached a depth practically unattainable. “The subterranean laboratory still exists, but the way to it was virtually closed at a comparatively early period in the earth’s history.” Greater progress has been made since the microscope was pressed into the service of geology, and inspires the hope that we shall yet learn something more of the earliest ages, when the mystery of life began.

“It may be regarded as one of the most remarkable results of geological science, that an acquaintance with organic forms is at least as necessary for a geologist as a knowledge of minerals, and that a correct knowledge of organic remains (portions of fossil plants and animals) should prove a more certain and unerring guide in unravelling the structure of complicated districts of countries, than the most wide and general acquaintance with inorganic substances. The cause of this, however, is obvious, as the mineral substances produced at any one period of a vast succession of ages, do not appear to have had any essential difference from those formed under like circumstances at another. The animals and plants, however, living at one period of the earth’s history were widely different from those living at other periods. There has been a continuous succession of different races of living beings on the earth following each other in a certain regular and ascertainable order, and when that order has been determined, it is equally certain that we can at once assign to its proper period of production, and therefore to its proper place in the series of rocks, any portion of earthy matter we may meet with containing any one, or even any recognisable fragment of one, of these once living beings.”

The method of preparing sections of minerals and rocks for microscopic examination will be found at pp. 241, 307-309. The sections, it is almost needless to say, must be prepared thin enough to permit the use of transmitted light, as well as for that of polarised light: that is to say, they should range from about 1/100th to 1/1000th of an inch. Almost any lapidary will cut sections of any choice specimen.[88] The formation of crystals, and the method of preparing them for examination, has also been fully explained in the chapter on polarised light, pp. 219 et seq., and illustrated on Plate VIII. It is well known in micro-chemistry that “almost every substance, simple or compound, capable of existing in the solid state, assumes, under favourable conditions, a distinct geometrical figure, usually bounded by plane surfaces and having angles of constant value.

Much useful information may be gained upon micro-crystallography, as well as on almost everything having any relation to the _technique_ of the microscope, in the “Journal of the Royal Microscopical Society.” To the June number (1898) Mr. T. Charters White contributes an article on crystals, and reminds us that the presence of much or little moisture will modify and alter forms, as much and as often as varying degrees of temperature. At the same time he offers a few useful suggestions for the purpose of securing better results, for which purpose he employs hippuric acid, hydroquinine, and picric acid alone or in combination with hippuric acid, and an aqueous solution of bichromate of potassium, crystallised in a tolerably thick emulsion of gum arabic. This is the only aqueous solution; the other solvents have been methylated spirit, acetone, and absolute alcohol, taking these three solvents as types of the greatest volatility, because in making certain crystals it is necessary that the solvent should evaporate quickly, otherwise the crystals will assume their original forms. It is further desirable to make saturated, or even super-saturated solutions of the three chemicals named, as the colours produced under polarised light are of a deeper and richer character than they are if made from weaker solutions. Of the three chemicals named he prefers hippuric acid, for reasons stated, that it is the most manageable, and allows of more time being taken in modifying the formation of the crystals. It is also advisable to slightly warm the glass slide before the drop of fluid is applied. On the whole, picric acid appears to furnish a greater variety of crystals when used in combination with bichromate of potassium and a solution of gum arabic.

APPENDICES AND TABLES USEFUL TO THE MICROSCOPIST.

APPENDIX A.

ILLUMINATION ARRANGEMENTS OF THE MICROSCOPE.

A doubt has of late been expressed among practical microscopists as to the value of the illumination arrangements of the lamp and the microscope, so as to secure the more perfect definition of the flagellate organ of the monas and other minute forms of infusorial life. We have been told that better results will be obtained by turning the mirror aside, and so disposing the microscope and lamp in the horizontal position, that the central rays of light from the mirror-edge of the lamp-flame shall pass through the optical axis of the achromatic condenser, the focus of which must be accurately brought upon the field of view by means of the substage centring screws and rack-work, and in such a manner, that by employing a 1-inch objective, a sharply-defined image of the lamp-flame, edge-on, is projected on to the centre of the field in association with the specimen under examination. If the 1-inch objective be now replaced by a 1-12th or 1-16th inch immersion and once again focussed into place, and a slight re-adjustment of the centring made, it will be found that the field is brilliantly illuminated, and the most minute portions of infusorial life are well defined, and with a sharpness otherwise unattainable. At the same time the graduating or iris diaphragm must be brought into use.

Dr. Clifford Mercer, the President of the American Microscopical Society, who has quite recently reinvestigated the question of illumination, utterly condemns the narrow cone, as well as that of oblique light in all such investigations, and considers the 3-4ths axil cone as the most suitable method for microscopical illumination, and he bases his resolving limit accordingly. Some important experiments are brought forward by Dr. Mercer, which at the same time demonstrate the correctness of Lord Rayleigh’s limit of resolution (referred to in a previous chapter, p. 44), for circular apertures as contrasted with that calculated by the late Sir George Airy.

With regard to the Abbé Theory, Dr. Mercer says: “Resolution in the Abbé Theory may be said to increase by bounds. So long as the central image of the source of light alone is to be seen at the back of the objective, resolution is not present. The aperture may be increased without change in the contraction of the diffraction pattern, and in accompanying resolution, so long as the central image alone is to be seen at the back of the objective; but the moment the increase in aperture is sufficient to uncover or admit one flanking spectrum image, resolution is present. With greater increase in aperture, no improvement in the picture as to the contraction of the diffraction pattern is to be seen until another spectrum image is uncovered or admitted. Dr. Mercer gives his reasons for considering that the advantageous reduction in a cone of light between an object and the objective should not exceed, in the case of first-class objectives, one-fourth to one-third (never more than one-half) of the diameter of the cone. On the other hand, with full cone illumination, resolution increases continuously, and not by jumps or by periodic accessions. With regard to the use of oblique light, he says his Photos 2, 3, and 4[89] are a pictorial warning for a second time against the use of oblique illumination in ordinary work us a means of increasing, or of attempting to exhaust the resolving power of the microscope. At the same time it becomes evident that every substage should be provided with a means by which its condenser may be accurately centred, and that every student using the microscope should be familiar with a method of centring his substage condenser.

Dr. Mercer summarises the results of his experiments thus:--

1. “Diffraction rays on leaving an object may be considered in the same category with other rays changed in direction by an object.

2. “The diffraction phenomena seen in a projected image are essentially the effect of changes in light _above_ the objective, due to a function of aperture, and not to changes _below_ the objective, due to diffraction of light in the plane of the object.

3. “Diffraction in the plane of the object does, under some circumstances, furnish light to certain parts of an aperture from which primary rays are absent, and this enables aperture to more fully determine the character of the projected image, resulting in a more nearly truthful image, or, on the other hand, in false appearances. This is the gist of the Abbé phenomena of microscopic vision.

4. “But such phenomena are not peculiar to microscopic vision, notwithstanding Professor Abbé’s claim to the contrary.

5. “With any positive lens similar and more brilliant results may be got by utilising corresponding pencils of primary rays, instead of isolated pencils of diffracted rays.

6. “Still more trustworthy results may be got by using primary rays in place of the isolated pencils of primary rays.

7. “An advantage peculiar to using narrow cone illumination with an objective of wide aperture (the only illumination admissible in the Abbé theory), consists in giving, under suitable conditions, approximately the acme of resolving power simultaneously in each several diameters. Thus a circular aperture is approximately squared or made rectangular as to resolving power in several of its diameters simultaneously.

8. “Special attention is called to the fact that the Abbé theory deals with complex objects; for only such objects are subject to resolution. Single particles and uniform areas are outside its domain. These latter, however, are microscopic objects, and all objects are essentially different shaped aggregations of points. An isolated point-like particle, no matter what its minuteness, may be seen if it present sufficient contrast with the surrounding microscopic field. The size of the disc image is no less than a limit determined finally by aperture. That limit in size varying inversely with aperture, determines the limit of resolving power. This is the gist of the theory of microscopic vision which harmonises with our experimental study of aperture.”

APPENDIX B.

MICRO-PHOTOGRAPHY.

Owing in some measure to the more complete knowledge of the subject gained by the experience of years, and the extreme value of micro-photography in the delineation of bacteria, and perhaps in a measure to the advent of the perfected dry-plate process, photography is being rapidly pressed forward in conjunction with the microscope. In the course of the year [1898] no less than six, more or less, new forms of micro-photographic apparatus have appeared; two are simple, one for daylight, one for lamp, one for electric, and one for lime-light illumination. Passing over the simpler forms, for a notice of which I am unable to find room, there is one piece of new apparatus, that of Mr. E. B. Stringer, which is not only new, but is in every way adapted to the work of micro-photography. It is in fact a well-arranged camera, fitted with a powerful condensing arrangement, each portion of which is capable of being independently centred and controlled. Indeed, the specially interesting feature of the apparatus is the control of the gas and the beautiful and uniformally illuminating disc of zircon, about a quarter of an inch in diameter.

This efficient photo-micrographic apparatus (Fig. 446) is made by Messrs. W. Watson & Sons, under the instructions of Mr. E. B. Stringer. The illuminating condensing system is mounted on a square brass bar, the illuminant being oxygen-hydrogen light burning on zirconium. Immediately in front of this is a condenser, c, four and a half inches diameter, with an iris diaphragm, D, immediately in front of it. The holder, E, carries the light filtering media through which the beam passes and enters the condenser, F. It then goes through a tank of water contained in the cone, F to H, and emerges a practically parallel beam of great intensity through a plano-concave lens, h, of such a diameter as to exactly fill the back lens of the substage condenser. There is an iris diaphragm, T, for cutting off stray light.

The whole of the apparatus is fitted with centring screws and clamps, and after having been once adjusted it is ready for use at any moment without preparation. By means of this apparatus, instantaneous pictures can be taken of living rotifers, so brilliant is the illumination, while photographs of such fine objects as the flagella of bacteria cannot be secured with the same amount of certainty by any other microphotographic apparatus with which I have made myself acquainted.

APPENDIX C.

FORMULÆ AND METHODS:--CEMENTING, CLEARING, HARDENING AND MOUNTING.[90]

CLEARING AGENTS.

The object of employing a clearing agent is to replace the alcohol in the dehydrated section by a liquid which has a refractive index about the same as the balsam into which it is to be placed, and which will readily mix with it.

OIL OF BERGAMOT will clear quickly from 90 per cent. of alcohol. Clove oil clears more rapidly, but it dissolves out aniline colours to a considerable extent. Xylol is without action on aniline colours. This strength of alcohol is chosen because of its being that of the methylated spirit sold in London, and which is much used in washing and dehydrating on account of its cheapness.

OIL OF CEDAR WOOD, although an essential oil, resembles xylol, but evaporates slowly. It has very little solvent action on the aniline colours. It clears rapidly from absolute alcohol, but not well from 90 per cent. Sections can be left in it for several days. It is a convenient medium in which to examine tissues before mounting them permanently. It clears celloidin without dissolving it; and as a connecting fluid between the object and objective nothing better has been discovered.

Other clearing agents have been tried, but as they dissolve out the aniline colours, are no longer used.

CEMENTS.

GROVE’S MASTIC AND BISMUTH.--Dissolve gum mastic in chloroform, and thicken with nitrate of bismuth. The solution of mastic should be nearly saturated.

GROVE’S OXIDE OF ZINC, DAMMAR, AND DRYING OIL.--Rub up well-ground oxide of zinc, 2 ozs., with drying oil, to the consistence of thick paint. Then add an equal quantity of gum dammar, previously dissolved in benzoline, and of the thickness of syrup. Strain through close-meshed muslin. Keep in well-corked bottle, and, if necessary, thin with benzoline.

ISINGLASS CEMENT.--Heat the isinglass in a covered vessel on the water-bath with a little glacial acetic acid, until it is thoroughly softened and forms a stiff mass, then gradually add more acid until it produces a thick solution which is of uniform consistence, and just fluid while hot. Then run into wide-mouth bottles and close with good corks.

KITTON’S CEMENT of white lead and red lead in powder, and litharge powder in equal parts. Grind together with a little turpentine, until thoroughly incorporated, and mix with gold size. The mixture should be thin enough to use with a brush; in using, one coat should be allowed to dry before applying another. No more cement should be mixed with the gold size than is required for immediate use, as it sets quickly, and becomes unworkable.

KRÖNIG’S CEMENT.--Gradually add ordinary resin, 7 to 9 parts, to melted beeswax, 2 parts, then steam and cool.

SHELLAC CEMENT.--Dissolve shellac in an equal weight of methylated spirit, then pour off the clear portion and add a few drops of balsam and castor oil.

MARINE GLUE.--Dissolve indiarubber in mineral naphtha, and add twice the quantity of powdered shellac; or make chloroform the solvent, and use mastic instead of shellac. For casting battery trays, use a composition of 4 parts resin and 1 of gutta percha, with a little boiled oil.

SELIER (_Cleaning Glass Slides_).--New slides or cover-glasses must be placed for a few hours in a mixture of 1 part of potassium bichromate, 1 of sulphuric acid, and 25 of water. Subsequently wash with water and wipe dry with a linen rag, after draining off the excess of moisture. Covers that have been used should be previously immersed for a few days in a mixture of equal parts of alcohol and hydrochloric acid. Scrape old slides free of mounting medium before immersing them in the bichromate solution.

ELSCHING’S CELLOIDIN SOLUTION.--Allow the celloidin shavings to swell up for 24 hours in the necessary quantity of absolute alcohol, then add the proper amount of ether.

KOCH’S COPAL.--Stain small pieces of material in bulk, and dehydrate with alcohol, then immerse in a thin solution of copal in chloroform. Evaporate with a gentle heat until the solution is so far concentrated as to draw out into threads that are brittle on cooling. Then remove the objects and leave on a tile for a few days to dry. Sections may then be cut by means of a fine saw. If objects are imbedded unstained, remove copal from sections by soaking in chloroform, decalcify if necessary, and stain.

EULENSTEIN’S CEMENT.--Mix equal parts of Brunswick black and gold size with a very little Canada balsam.

DECALCIFYING AND BLEACHING.

In the case of bony structures, or tissues so impregnated with calcium salts, the material should be decalcified by an acid capable of dissolving out the mineral matter. Hydrochloric acid with alcohol is in more general use. The older the bone the stronger will be the acid required, nitric with alcohol and chromic acid. Picric acid is preferred for fœtal bone.

ANDEER, J. J., finds an aqueous solution of phloroglucin acts as a powerful decalcifying agent on the bones of animals, but is without action on the most delicate organic tissue. If treatment with hydrochloric acid be employed as well, the residual “ossein” will be without a trace of either calcium phosphate or carbonate.

EBNER’S FLUIDS.--(1) Mix 100 C.c. of cold saturated aqueous solution of sodium chloride, 100 C.c. of water, and 4 C.c. of hydrochloric acid. Preparations are placed in the fluid, and 1 to 2 C.c. of hydrochloric acid added daily until they are soft. (2) Mix 2·5 parts of hydrochloric acid (sp. gr. 1·16) with 500 of alcohol (90 per cent.), 100 of water, and 2·5 of sodium chloride.

FOL’S LIQUID.--Mix 70 volumes of 1 per cent. chromic acid, 3 of nitric acid, and 200 of water.

MAYER’S DESILIFICATION PROCESS.--Place the objects in alcohol contained in a glass vessel coated internally with paraffin, then add hydrofluoric acid drop by drop until desilification is complete, avoiding the fumes meanwhile.

MARSH’S CHLORINE METHOD.--Chlorine is generated in a small bottle by treating crystals of potassium chlorate with strong HCl., and the gas is led through a piece of glass tubing, bent twice at right angles, to the bottom of a bottle containing the sections immersed in water.

RANVIER’S FLUID.--Use 50 per cent. hydrochloric acid with the addition of sodium chloride to counteract its swelling action.

SQUIRE’S FLUID.--(1) Mix 95 parts of glycerine with 5 parts of hydrochloric acid; used for softening teeth. (2) Use a 4 per cent. aqueous solution of arsenic acid at a temperature of 30° to 40° C. After softening tissues in this solution, keep them in alcohol.

WALDEYER.--To a 0·1 per cent. solution of palladium chloride, add one-tenth its volume of hydrochloric acid.

HARDENING, FREEZING, AND EMBEDDING.

ALTMANN (_Fixing Solution_).--A mixture of equal parts of 5 per cent. potassium bichromate solution and 2 per cent. osmic acid.

ALCOHOL.--Strengths of alcoholic solutions, as given by Squire, will be found of practical value. Absolute alcohol (sp. gr. O·797) containing about 98 per cent. of ethylic alcohol is taken as the basis in most instances. Alcohol of 90 per cent. (sp. gr. 0·823) is prepared by mixing 14 volumes of absolute alcohol and 1 volume of distilled water; 84 per cent. alcohol (sp. gr. 0·838) is rectified spirit B.P.; 70 per cent. alcohol (sp. gr. 0·872) may be obtained by adding 1 volume of distilled water to 3 volumes of absolute alcohol, 6 volumes of rectified spirit, or 4 volumes of methylated spirit; 50 per cent. alcohol (sp. gr. 0·918) is prepared by adding 4 volumes of distilled water to 5 volumes of absolute alcohol, 3 volumes of water to 5 volumes of rectified spirit, or 3·5 volumes of water to 5 volumes of methylated spirit. Absolute alcohol, 75 C.c., mixed with acetic acid, 25 C.c., serves as an excellent fixing agent for nuclei. Immerse tissues in it for 6 to 12 hours, then transfer to 90 per cent. alcohol until hardened, afterwards preserving in 70 per cent. alcohol till wanted.

BETZ’S HARDENING FLUID.--A mixture of equal parts of sulphuric ether and alcohol. This is used for hardening the brain of insects prior to cutting sections.

COLE’S FREEZING PROCESS.--Dissolve picked gum acacia, 4 ozs., in distilled water, 6 ozs., and to each 5 parts of the resulting mucilage add 3 parts of syrup made by dissolving loaf sugar, 1 lb., in distilled water, 1 pint. To each ounce of the medium add 5 grains of pure carbolic acid, and soak the tissues in it prior to freezing. For tissues liable to come to pieces, mix 4 parts of syrup with 5 of mucilage.

FLEMMING’S FIXING SOLUTION.--Osmic acid (1 per cent. solution), 80 C.c.; chromic acid (10 per cent. solution), 15 C.c.; glacial acetic acid, 10 C.c.; distilled water, 95 C.c.

FOL’S FIXING--Osmic acid (1 per cent. solution), 4 C.c.; chromic acid (10 per cent. solution), 5 C.c.; glacial acetic acid, 10 C.c.; distilled water, 181 C.c.

FISCHER’S IMBEDDING MASS.--Dissolve 15 parts of transparent soap in 17·5 parts of 96 per cent. alcohol.

KLEIN’S HARDENING.--Mix 1 C.c. of 10 per cent. chromic acid solution with 60 C.c. of water, and add 30 C.c. of 90 per cent. alcohol.

MÜLLER’S FLUID FORMULA, see page 288.--This solution is sometimes mixed with one-third its volume of 90 per cent. alcohol, its hardening action being then much more rapid.

RABL’S HARDENING FLUID.--Chromic acid solution (10 per cent.), 7 C.c.; water, 200 C.c.; formic acid (sp. gr. 1·2), 5 drops.

ROLLETT’S FREEZING PROCESS.--Small portions of tissue placed on the stage of microtome, after immersion in the white of an egg, then frozen and cut with a very cold knife.

RYDER (_Double Embedding_).--After the celloidin bath, soak objects in chloroform, then remove into a mixture of chloroform and paraffin, heated to not more than 40° C., and finally into a bath of pure paraffin.

STRICKER (_Imbedding Mass_).--Prepare the objects in alcohol and imbed in a concentrated solution in gum arabic in a paper case, then throw the whole into alcohol and cut after 2 or 3 days.

WEBB (_Dextrin Freezing_).--A thick solution of dextrin (1:40) in aqueous solution of carbolic acid is used for imbedding, and subsequently frozen.

MOUNTING MEDIA.

Sections are usually mounted in balsam, dammar, glycerine, &c., but it is not a necessity that the cover-glass should be fixed or cemented down. Some cements (caoutchouc by preference) should be employed when glycerine or aqueous (Farrant’s) media are used.

ALLEGER’S GELATINE PROCESS.--Add a few drops of formalin to each gramme of 0·5 to 1 per cent. gelatine solution. After mounting the section in this, apply heat to the slide until the paraffin is softened, and allow the superfluous gelatine to drain from the edge of the slide.

APÁTHY’S MOUNTING MEDIUM.--Picked gum arabic, 50 Gm.; cane-sugar, 50 Gm.; distilled water, 50 Gm.; dissolve over a warm bath and add 0·05 Gm. of thymol. This medium sets very hard, and combined with a paper cell it may be used for ringing glycerine mounts.

COLE’S SLOW OR EXPOSURE METHOD OF MOUNTING.--Dissolve dried Canada balsam, 3 ozs., in benzole, 3 fl. ozs., and filter. Apply a clean cover-glass to a slide that has been moistened by breathing on it, and place a few drops of the balsam solution on the cover-glass. Then remove a section from turpentine, and put it into the balsam. Put aside for 12 hours to allow the benzole to evaporate, and having warmed a slide and added a drop of fresh balsam solution to that on the cover-glass, bring the fluid balsam in contact with the warmed slide. Press the cover down carefully to avoid the inclusion of air bubbles, and when the excess of balsam is squeezed out, put the slide aside to cool, after which it may be cleaned with a camel-hair brush or soft rag moistened with methylated spirit.

FARRANT’S SOLUTION.--Take of gum arabic 5 parts; water 5 parts; when the gum is fairly dissolved add 10 parts of a 5 per cent. solution of carbolic acid.

FLEMMING’S GLYCERINE PRESERVATIVE.--Mix equal parts of alcohol, glycerine, and water. Lee recommends the addition of 0·5 to 0·75 per cent. of acetic acid.

LEE’S TURPENTINE COLOPHONIUM MOUNTING MEDIUM.--This is highly recommended for general work, and is prepared by adding small pieces of colophonium to rectified oil of turpentine, heating in a stove, and when the solution is sufficiently thick filtering twice in the stove.

SEAMAN (_Glycerine Jelly_).--Dissolve isinglass in water so as to make a jelly that remains stiff at the ordinary temperature of the room, and add one-tenth part of glycerine, together with a little solution of borax, carbolic acid, or camphor water. Filter through muslin whilst warm and add a little alcohol.

SEILER (_Alcohol Balsam_).--Heat Canada balsam until it becomes brittle when cold, then dissolve in warm absolute alcohol and filter through absorbent cotton-wool. This is chiefly useful as a mounting medium for objects stained with carmine.

SQUIRE (_Farrant’s Medium_).--Dissolve in 200 C.c. of distilled water 1 Gm. of arsenious acid and 130 Gm. of gum arabic, then add 100 C.c. of glycerine. Filter through fine Swedish filter paper upon which has been deposited a thin layer of talc.

SQUIRE (_Glycerine and Gum_).--Dissolve 130 Gm. of gum arabic in 200 C.c. of chloroform water (1 in 200), then add 100 C.c. of glycerine and filter.

SQUIRE (_Glycerine Jelly_).--Soak 100 Gm. of French gelatine in chloroform water, drain when soft, and dissolve with heat in 750 Gm. of glycerine. Add 400 Gm. of chloroform water, with which has been incorporated about 50 Gm. of fresh egg albumen, mix thoroughly, and heat to boiling point for about 5 minutes. Make up the total weight to 1550 Gm. with chloroform water and filter in a warm chamber.

SQUIRE (_Canada Balsam_).--Dry the balsam over a water bath until brittle when cooled, then to each 200 Gm. add 100 C.c. of benzole or rather less xylol.

SQUIRE (_Dammar Solution_).--(1) Dissolve 100 Gm. of dammar in 100 C.c. of benzole. (2) Dissolve 100 Gm. of dammar in 200 C.c. of turpentine oil, and add 50 Gm. of mastic dissolved in 200 C.c. of chloroform.

SQUIRE (_Potassium Acetate Solution_).--Dissolve 250 Gm. of potassium acetate in 100 C.c. of water, by the aid of gentle heat, and filter. This is used as a mounting medium.

SQUIRE (_Treatment of Sections_).--Imbed tissues to be cut in paraffin melting between 45° and 50° C., according to the temperature of the room and the nature of the material. Afterwards preserve the sections, prior to staining and mounting, in 50 per cent. alcohol, or in a mixture of equal volumes of glycerine and thymol water (1 in 1500). Sections may be conveniently washed in alcohol, dehydrated, and cleared, in small wide-mouthed bottles.

TOPPING’S SOLUTION.--Mix 1 part of absolute alcohol with 5 parts of water, or 4 parts of water and 1 part of aluminium acetate. Add an equal volume of glycerine before use.

STAINS AND STAINING METHODS.

APÁTHY’S HÆMATOXYLIN STAIN.--After staining in 1 per cent. solution of hæmatoxylin in 70 or 80 per cent. alcohol, wash out in 1 per cent. solution of potassium bichromate in alcohol of the same strength. The bichromate solution should be freshly made by mixing 1 part of a 5 per cent. aqueous solution with about 4 parts of 80 to 90 per cent. alcohol.

ALFEROW (_Silver Staining_).--An acid solution of silver picrate, lactate, acetate, or citrate, is prepared by adding to 800 C.c. of the solution 10 to 15 drops of a concentrated solution of the acid of the salt taken.

BETHE’S STAIN FOR CHITIN.--Place series of mounted sections on slides in a freshly prepared 10 per cent. solution of aniline hydrochloride, containing 1 drop of hydrochloric acid for each 10 C.c., for 3 or 4 minutes, then rinse in water, and put the slide with sections downwards in a 10 per cent. solution of potassium bichromate. The process may be repeated if the stain is not sufficiently intense, but the sections must be well rinsed with water after each immersion.

BEALE’S AMMONIA CARMINE.--Carmine, 10 grs.; strong solution of ammonia, 30 mins.; distilled water, 2 ozs.; alcohol, 0·5 oz.; glycerine, 2 ozs. Dissolve the carmine in the ammonia by the aid of heat, boil for a few seconds, and let the solution cool. Then allow the excess of ammonia to evaporate, add the other ingredients, and filter. If any carmine should deposit on keeping add one or two drops of ammonia solution to redissolve it.

BENDA’S COPPER HÆMATOXYLIN.--Harden the material with chromic acid or Flemming’s solution and leave sections for 24 hours in a 5 per cent. solution of neutral copper acetate at a temperature of about 40° C., wash out well with distilled water, and stain to a dark grey or blackish tint in a saturated aqueous hæmatoxylin solution. Decolourise the sections in 0·2 per cent. hydrochloric acid until light yellow, put back into the copper solution until they turn bluish-grey, then wash, dehydrate, clear, and mount in balsam.

BISMARCK BROWN.--Vesuvine 0·5 Gm., rectified spirit 2, and distilled water 80 C.c.; or a concentrated alcoholic solution may be kept ready for dilution.

BOCHMER’S HÆMATOXYLIN.--Dissolve (_a_) crystallised hæmatoxylin, 1 Gm., in absolute alcohol, 10 C.c., and (_b_) alum ammonia, 10 Gm., in distilled water, 200 C.c. Mix the two solutions, and allow to ripen for some days before use. Filter after standing a week. Wash out with aqueous solution of alum (0·5 per cent.) or with acids.

CALBERLA’S INDULIN STAIN.--Dilute a concentrated aqueous solution with 6 volumes of water and stain sections for 5 to 20 minutes. Afterwards wash in water or alcohol, and examine in glycerine or clove oil.

CALBERLA’S MACERATING MIXTURE (for nerve and muscle of embryos).--Dissolve potassium chloride, 0·4 Gm., sodium chloride, 0·3 Gm., sodium phosphate, 0·2 Gm., and calcium chloride, 0·2 Gm., in water, 100 Gm., saturated with carbon dioxide just before using. Mix one volume of this solution with half a volume of Müller’s solution and one volume of water. The Müller’s solution may be replaced by a 2·5 per cent. solution of ammonium chromate. Tissues macerated in this mixture are isolated by teasing and shaking, and mount specimens in concentrated potassium acetate solution.

CANOY’S SALT SOLUTION.--Add a trace of osmic acid to a 0·75 per cent. solution of sodium chloride in water.

CHENZINSKY’S METHYLENE BLUE AND EOSINE.--Mix saturated aqueous solution of methylene blue, 40 parts, with 0·5 per cent. solution of eosine in 70 per cent. alcohol, 20 parts, and distilled water or glycerine, 40 parts.

COHNHEIM’S GOLD METHOD.--Place pieces of tissue in 0·5 per cent. gold chloride solution until quite yellow, then expose to light in water acidulated with acetic acid until the gold is thoroughly reduced. Mount specimens in acidulated glycerine.

CROOKSHANK’S METHOD OF STAINING FLAGELLA.--Cover-glass preparations are stained with a drop of concentrated alcoholic solution of gentian violet, then rinsed in water, allowed to dry, and mounted in balsam.

CZOKER’S ALUM COCHINEAL.--Dissolve alum 1 Gm. in distilled water, 100 C.c., add powdered cochineal, 1 Gm., and boil; evaporate down to half of its original bulk, filter, and add 1/2 C.c. of liquid carbolic acid.

DELAFIELD’S HÆMATOXYLIN.--Dissolve hæmatoxylin, 4 Gm., in absolute alcohol, 25 C.c., and add the solution to 400 C.c. of a saturated aqueous solution of ammonia alum. Expose the mixture to light and air for 3 or 4 days, then filter and add glycerine, 100 C.c., and methylic alcohol, 100 C.c. Again expose the solution to light until it becomes dark-coloured, then filter and preserve in a stoppered bottle.

EHRLICH’S ACID HÆMATOXYLIN.--Dissolve hæmatoxylin, 2 Gm., in absolute alcohol, 100 C.c., and add glycerine, 100 C.c., distilled water, 100 C.c., ammonia alum, 2 Gm., glacial acetic acid, 10 C.c. Expose to daylight for at least a month before use, removing the stopper at intervals.

EHRLICH’S HÆMATOXYLIN (AMMONIATED).--Dissolve ammonium carbonate, 0·4 Gm., and hæmatoxylin, 2 Gm., in proof spirit, 40 C.c., and expose to the air in a shallow dish for 24 hours. Then make up the volume to 40 C.c. with proof spirit (warming if necessary to re-dissolve any separate crystals), and add ammonia alum, 2 Gm., dissolved in distilled water, 80 C.c., together with glycerine, 100 C.c., rectified spirit, 80 C.c., and glacial acetic acid, 10 C.c.

EHRLICH-BIONDI MIXTURE (or Ehrlich-Biondi-Heidenheim mixture).--Dissolve (_a_) methyl green, 0·5 Gm., in distilled water, 100 C.c.; (_b_) acid fuchsine, 0·5 Gm., in distilled water, 40 C.c.; (_c_) orange, 2 Gm., in distilled water, 200 C.c. Mix the three solutions and filter before use. Stain sections for 12 hours, then wash, dehydrate, clear, and mount.

EHRLICH-WEIGERT-KOCH’S GENTIAN-VIOLET-ANILINE-WATER.--Aniline water, 100 C.c., concentrated alcoholic solution of gentian violet, 11 C.c.; absolute alcohol, 10 C.c.

EVERARD, DEMOOR, AND MASSART’S HÆMATOXYLIN-EOSINE.--Dissolve alum, 20 Gm., in water, 200 Gm., by the aid of heat, then filter, and after 24 hours add a solution of hæmatoxylin, 1 Gm., in alcohol, 10 Gm. Let the solution stand for 8 days, again filter, and mix with an equal volume of the following solution:--Eosine, 1 Gm., alcohol, 25 Gm., water, 75 Gm., glycerine, 50 Gm.

FLEMMING’S GENTIAN VIOLET METHOD.--Use a concentrated alcoholic solution of Gentian Violet diluted with about one half its bulk of water. Differentiate the stained objects in alcohol acidulated with about 0·5 per cent. of hydrochloric acid, followed by pure alcohol and clove oil.

FLEMMING’S ORANGE METHOD.--Stain for days or weeks in strong alcoholic safranine solution diluted with half its bulk of aniline water (saturated); then rinse in distilled water, differentiate in absolute alcohol containing 0·1 per cent. of hydrochloric acid, stain for 1 to 3 hours in strong aqueous gentian violet solution, again wash in distilled water, and finally treat with concentrated aqueous solution of Orange. After a few minutes transfer sections to absolute alcohol, then clear in clove or bergamot oil, and mount in dammar or balsam.

FOL’S FERRIC CHLORIDE FIXING AND STAINING PROCESS.--Preparations are treated with tincture of ferric chloride diluted with 5 to 10 times its bulk of 70 per cent. alcohol, and then transfer for 24 hours to alcohol containing a trace of gallic acid.

FREY’S FUCHSINE SOLUTION.--A solution of 0·01 Gm. of crystallised fuchsine, 20 to 25 drops absolute alcohol, and 15 C.c. of water.

FRIEDLAENDER’S STAINING METHODS.--Cover-glass preparations are treated for 3 minutes with a 1 per cent. solution of acetic acid, and allowed to dry after removal of excess of liquid by filter paper. Next place them in gentian violet aniline water (aniline water, 100 C.c., concentrated alcoholic solution of gentian violet, 11 C.c.; absolute alcohol, 10 C.c.) for half a minute, wash in water, mount and dry in balsam. Sections are kept for 24 hours in a warm place, in the following solution:--Concentrated alcoholic solution of gentian violet, 50 C.c.; distilled water, 100 C.c.; glacial acetic acid, 10 C.c. Then treat for 1 or 2 minutes with 0·1 per cent. acetic acid, dehydrate, clear, and mount in balsam.

GAFFKY’S STAINING METHODS.--Sections of material hardened in alcohol are left for 20 to 24 hours in a deep blue opaque solution, freshly made by adding saturated alcoholic solution of methylene blue to distilled water. Then wash in distilled water, dehydrate in absolute alcohol, clear in turpentine oil, and mount in balsam.

GIACOMI’S STAINING METHOD.--Stain cover-glass preparations for a few minutes in a hot solution of fuchsine, then place in water containing a few drops of ferric chloride solution, and afterwards decolourise in strong ferric chloride solution. If any precipitate be formed with the iron solution, complete the decolourisation in alcohol. Counterstain with vesuvine.

GIBBES’ DOUBLE STAINING METHOD.--Well mix magenta, 2 Gm., and methylene blue, 1 Gm., then add slowly aniline oil, 3 C.c., dissolve in rectified spirit, 15 C.c. Subsequently add 15 C.c. of distilled water and keep the stain in a stoppered bottle. Cover-glass preparations are placed for 4 minutes in the slightly heated stain and sections left for some hours in the stain at the ordinary temperature. Afterwards, wash in methylated spirit until no more colour comes away, then dehydrate, clear in cedar oil, and mount in balsam.

GIBBES’ MAGENTA STAIN.--Mix magenta, 2 Gm.; aniline oil, 3 Gm.; rectified spirit, 20 C.c.; and distilled water, 20 C.c.

GOLGI’S SUBLIMATED METHOD.--Small cubes of tissue are hardened for 15 to 30 days in Müller’s fluid, which should be frequently changed. Then transfer for 8 to 10 days to 0·25 to 1 per cent. aqueous mercuric chloride solution, which must be changed, as it becomes coloured. If desired, treat subsequently with weak sodium sulphide solution to darken the stain and make it sharper. After cutting sections from material thus prepared they must be well washed with water.

GRAM’S STAIN FOR BACTERIA.--This is prepared by shaking 15 drops of aniline oil with 15 Gm. of water, filtering the solution and adding to the filtrate 4 to 5 drops of saturated alcoholic solution of gentian violet. Or shake 3·3 C.c. of aniline with 100 C.c. of distilled water and, after filtering, add 11 C.c. of concentrated alcoholic solution of gentian violet and 10 C.c. of absolute alcohol. After preparations have been stained for 1 to 3 minutes in one of the above they are quickly rinsed in absolute alcohol and then placed in Gram’s solution of iodine in potassium iodine (iodine, 1 Gm.; potassium iodine, 2 Gm.; water, 300 C.c.), until they have acquired a brown colour. This takes about 1 to 3 minutes, and they are next washed in 90 per cent. alcohol until they become pale yellow, then dehydrated, cleared, and mounted in balsam. Counterstain with eosine or vesuvine if desired.

GRAM’S SOLUTION.--Iodine, 1 Gm.; potassium iodine, 2 Gm.; distilled water, 300 Gm.

GRENACHER’S ALUM CARMINE.--Dissolve 5 Gm. of ammonium alum in 100 C.c. of distilled water, add 1 Gm. of carmine, and boil for 20 minutes, filter when cool, and add distilled water to make up to 100 C.c.

GRENACHER’S ALCOHOLIC BORAX CARMINE.--Dissolve 4 Gm. of borax in 100 C.c. of distilled water, then add 3 Gm. of carmine, and heat gently. Finally, add 100 C.c. of 70 per cent. alcohol, filter the solution, if necessary, before use. Pieces of tissues are stained in this for 1 to 3 days, and then transferred to 70 per cent. alcohol, containing 0·5 to 1 per cent. of hydrochloric acid.

HEIDENHAIN’S HÆMATOXYLIN METHOD.--Dissolve (_a_) hæmatoxylin, 1 Gm., in distilled water, 300 C.c.; (_b_) potassium chromate, 1 Gm., in distilled water, 200 C.c. Small pieces of tissue hardened in alcohol or picric acid are placed in (_a_) for 12 to 24 hours, and then transferred for a similar length of time to (_b_). Wash thoroughly in water, dehydrate in alcohol, and imbed in paraffin.

HENLE’S STAIN (_for nervous tissue_).--Sections are left in palladium chloride solution (1:300 to 1:600) till they are of a straw colour, then rinsed in water and stained with strong ammonia carmine.

HENNEGUY’S ALUM CARMINE.--Excess of carmine is boiled in saturated solution of potash alum, and 10 per cent. of glacial acetic acid added on cooling. Allow to settle for some days, and then filter.

HENNEGUY’S PERMANGANATE METHOD.--Treat sections for 5 minutes with 1 per cent. potassium permanganate solution, then wash in water and stain with safranine, rubin, gentian violet, vesuvine, preference being given to a safranine solution prepared with aniline water.

HERMANN’S PLATINO-ACETO-OSMIC MIXTURE.--Mix 15 parts of 1 per cent. platinic chloride solution, 1 part of glacial acetic acid, and 2 or 4 parts of 2 per cent. osmic acid.

HERTWIG’S MACERATING FLUID.--Mix equal parts of 0·05 per cent. osmic acid, and 0·2 per cent. acetic acid. Medusæ are treated with this mixture for 2 or 3 minutes, then washed in 0·1 per cent. acetic acid until free from osmic acid. Leave them for 24 hours in the dilute acetic acid, then wash in water, stain with Beale’s carmine, and mount in glycerine. For Actiniæ use 0·04 per cent. osmic acid and make both solutions with sea water. Wash out with 0·2 per cent. acetic acid, and stain with picro-carmine.

HESSERT’S METHOD FOR STAINING FLAGELLA.--Fix the film by treating cover-glass preparations with a saturated alcoholic solution of mercuric chloride, wash, and stain for 30 or 40 minutes in a hot 10 per cent. aqueous solution of saturated alcoholic solution of fuchsine.

HOFFMANN’S BLUE STAIN.--Dissolve 1 Gm. of Hoffmann’s blue in 20 C.c. of rectified spirit and 80 C.c. of distilled water, then add 0·5 C.c. of glacial acetic acid. As a nuclear stain immerse sections for 10 minutes or more, rinse in water, wash in 90 per cent. alcohol, dehydrate, clear, and mount in balsam. To stain sieve areas, less time is required, 5 to 10 minutes, rinse in distilled water, and mount in glycerine; or dehydrate, clear, and mount in balsam.

HOYER’S SHELLAC INJECTION MASS.--Dissolve shellac in 80 per cent. alcohol to the consistency of a thin syrup, and strain through muslin of medium thickness. Colour with aniline colours in alcoholic solution, or by means of vermilion or other pigment suspended in alcohol.

HOYER’S SILVER NITRATE GELATINE MASS.--Mix a concentrated solution of gelatine with an equal volume of a 4 per cent. silver nitrate solution and warm, then add a very small quantity of aqueous pyrogallic acid solution to reduce the silver salt, and add chloral and glycerine as in the carmine gelatine mass.

HOYER’S SILVER STAIN.--Add ammonia to a solution of silver nitrate of known strength, until the precipitate formed just re-dissolves, then dilute the solution until it contains 0·75 to 0·50 per cent. of the salt.

KAISER’S BISMARCK BROWN STAIN. Sections are stained for 48 hours, at a temperature of 60 C., in a saturated solution of Bismarck brown in 60 per cent. alcohol, and washed out in 60 per cent. alcohol containing 2 per cent. of H.C.L., or 3 per cent. of acetic acid.

KAISER’S NERVE STAIN.--This is a modification of Weigert’s process. The material is hardened in Müller’s solution for 2 or 3 days, then cut into slices 2 to 4 Mm. thick, and treated with the solution for 5 or 6 days more. Subsequently immerse in Marchi’s solution for 8 days, then wash, pass through alcohol, and imbed in celloidin. Sections are mordanted for 5 minutes in the following mixture:--Solutions of ferric chloride, 1 part; distilled water, 1 part; rectified spirit, 8 parts. Next wash in Weigert’s hæmatoxylin, and warm in a fresh quantity of the same for a few minutes, wash with water, differentiate in Pal’s solution, and neutralise the oxalic acid by washing in water containing a little ammonia.

KAISER’S STAIN FOR THE SPINAL CORD.--Sections are stained for a few hours in solution of náphthylamine brown, 1 part, in water, 200 parts, and alcohol, 100 parts. Afterwards wash with alcohol and clear with origanum oil.

KALLIN’S NEUROLOGICAL METHOD.--Dissolve hydroquinone, 5 Gm., sodium sulphite, 40 Gm., and potassium carbonate, 75 Gm., in 25 Gm. of distilled water. At the time of using, dilute this solution with one-third to one-half its bulk of absolute alcohol; immerse sections of silvered material for several minutes until reduction is complete. Then place them in 70 per cent. alcohol for 10 to 15 minutes, and subsequently leave in aqueous solution of sodium hyposulphite (1:5) for 24 hours or more. Finally dehydrate and mount. Carmine may be used as an afterstain.

KLEINENBERG’S SOLUTION (_Improved Formula_).--Hæmatoxylin, 2-1/2 Gm.; crystallised calcium chloride, 20 Gm. in 10 C.c. of distilled water; alum, 3 Gm. in 16 C.c. of distilled water; rectified spirit, 240 C.c. Dissolve the calcium chloride and alum in their respective quantities of water by the aid of heat; mix the solutions and immediately dilute with rectified spirit; after an hour filter and add the hæmatoxylin. This makes a good working solution which keeps well. Of course it contains the alumina in solution, not as alum but aluminium chloride. If in special cases the colour is considered too strong, the dilution (when staining in bulk) must be made with some of the solution to which hæmatoxylin has not been added.

KOCH’S METHOD FOR STAINING FLAGELLA.--Immerse cover-glass preparations in a 1 per cent. aqueous solution of hæmatoxylin, then transfer to a 5 per cent. solution of chromic acid or to Müller’s fluid; dry and mount in balsam.

KOCH-EHRLICH, BACILLI.--Place sections, or cover-glass preparations, for at least 12 hours in gentian violet, or fuchsine aniline water (aniline water, 100 C.c.; concentrated alcoholic solution of gentian violet, or fuchsine, 11 C.c.; absolute alcohol, 10 C.c.), then immerse in a mixture of pure nitric acid (sp. gr. 1·42), 10 C.c., and distilled water, 30 C.c., for some seconds. Rinse in 60 per cent. alcohol for a few minutes, and then counterstain with vesuvine (vesuvine, 0·5 Gm.; rectified spirit, 20 C.c.; distilled water, 80 C.c.) after gentian violet; or methylene blue (methylene blue, 0·25 Gm.; rectified spirit, 20 C.c.; distilled water, 80 C.c.) after fuchsine. Finally rinse in water, dehydrate, clear, and mount in balsam. According to Squire, who points out that nitric acid is apt to injure delicate sections, Watson Cheyne recommends that sections should be transferred from fuchsine aniline water to distilled water, then rinsed in alcohol, and placed in the following contrast stain for 1 or 2 hours:--Saturated alcoholic solution of methylene blue, 20 C.c.; distilled water, 100 C.c.; formic acid (sp. gr. 1·2), 1 C.c.

KÜHNE’S CARBOLIC METHYLENE BLUE.--Rub up 1·5 Gm. of methylene blue with 10 C.c. of absolute alcohol, and add 100 C.c. of a 5 per cent. aqueous solution of carbolic acid.

KÜHNE’S METHYL VIOLET SOLUTION.--Dissolve 1 Gm. of methyl violet in 90 C.c. of distilled water and 100 C.c. of alcohol.

KÜHNE’S ANILINE OIL SOLUTIONS.--Rub up as much methylene blue, methyl green, or safranine as will go upon the point of a knife, with 10 C.c. of aniline, and allow to settle.

KÜHNE’S CARBOLIC FUCHSINE OR BLACK BROWN.--Dissolve 1 Gm. of fuchsine or black brown in 10 C.c. of absolute alcohol, and add 100 C.c. of a 5 per cent. aqueous solution of carbolic acid.

KÜHNE’S MODIFICATION OF GRAM’S METHOD.--Stain nuclei with carmine, then treat sections for 5 minutes in methyl violet solution, diluted one-sixth with a 1 per cent. aqueous solution of ammonium carbonate, or in a solution of Victoria blue, 0·25 Gm., in rectified spirit, 20 C.c., and distilled water, 80 C.c. Next rinse thoroughly in water and transfer to Grain’s solution for 2 to 3 minutes; again rinse in water and extract excess of stain with solution of yellow fluorescine, 1 Gm., in absolute alcohol, 50 C.c. Finally, pass through pure alcohol, aniline, terebene, and xylol, and mount in balsam.

LÖFFLER’S SOLUTION.--Concentrated alcoholic solution of methylene blue, 30 C.c.; solution of (caustic potash) potassium hydrate (1:10,000), 100 C.c. Mix and filter shortly before use. Sections are stained for a few minutes (tubercle sections for some hours), and excess of stain can be removed by immersion for a few seconds in 0·5 per cent. acetic acid. Dehydrate in absolute alcohol, clear in cedar oil, and mount in balsam. Löffler found that most bacteria stained better in this solution than in the weaker solutions used by Koch for turbercle bacillus.

LAVDOWSKY’S BILBERRY JUICE STAIN.--Well wash the fresh berries of _Vaccinium myrtillus_, then express the juice and mix with twice its bulk of distilled water, mixed with a little 90 per cent. alcohol. Heat for a short time and filter whilst warm. Dilute the stain with 2 or 3 volumes of distilled water before use.

LEE’S FORMALDEHYDE SOLUTIONS.--(1) Mix 1 part of 40 per cent. formaldehyde solution with two parts of 1 per cent. chromic acid solution, and add 4 per cent. of acetic acid. (2) Mix 1 part of 40 per cent. formaldehyde solution with 4 parts of 1 per cent. platinic chloride solution, and add 2 per cent. of acetic acid.

LEE’S OSMIC ACID AND PYROGALLOL STAIN.--Fix the tissues in Hermann’s mixture or Flemming’s mixture for half an hour, then place in a weak solution of pyrogallol, which may be prepared with alcohol in some cases. Safranine may be used as a second stain.

MARTINOTTI’S PICRO-NIGROSINE STAIN.--Pathological objects are stained for 2 or 3 hours or days, in a saturated solution of nigrosine in saturated alcoholic picric acid solution. Then wash out in a mixture of 1 part of formic acid with 2 parts of alcohol until the grey matter appears clearly differentiated from the white to the naked eye.

MAYER’S ALUMINIUM CHLORIDE CARMINE.--Dissolve 1 Gm. of carminic acid and 3 Gm. of aluminium chloride in 200 C.c. of water.

MAYER’S BERLIN BLUE INJECTION.--Add a solution of 10 C.c. of tincture of ferric chloride in 500 C.c. of water, to a solution of 20 Gm. of potassium ferrocyanide in 500 C.c. of water, allow to stand for 12 hours, decant, wash the deposit for 1 or 2 days with distilled water until the washings come through dark blue, then dissolve the blue in about a litre of water.

MAYER’S CARMALUM.--Dissolve 1 Gm. of carminic acid and 10 Gm. of alum in 200 C.c. of distilled water; decant, or filter, and add a few crystals of thymol, 0·1 per cent. of salicylic acid, or 0·5 per cent. of sodium salicylate. A weaker solution contains 3 to 5 times as much alum and 5 times as much water.

MERBEL’S CARMINE AND INDIGO FLUIDS (give a blue and red stain, and are very selective).--To prepare the red fluid, take--Carmine, 2 dr.; borax, 2 dr.; distilled water, 4 ozs. For the blue fluid, take--Indigo carmine, 2 dr.; borax, 2 dr.; distilled water, 4 ozs. Mix each in a mortar, and allow it to stand, then pour off the supernatant fluid. If the sections have been hardened in chromic acid, picric acid, or a bichromate, they must be washed in water till no tinge appears. Place them in alcohol for fifteen or twenty minutes, then in the two fluids mixed in equal proportions, after which wash them in a saturated aqueous solution of oxalic acid, where they should remain a rather shorter time than in the staining fluids. When sufficiently bleached, wash them in water, to get rid of the acid, then pass them through spirit and oil of cloves, and mount in balsam or dammar.

MITROPHANOW’S GOLD PROCESS FOR PRICKLE-CELLS AND INTERCELLULAR CANALS.--Wash the tail of an axolotl larva with distilled water, place for an hour in a watch-glassful of 0·25 per cent. solution of gold chloride, containing 1 drop of hydrochloric acid; wash, and reduce in a mixture of 1 part of formic acid with 6 parts of water.

MITROPHANOW’S MACERATION METHOD FOR EPITHELIUM.--Fix the embryo for 15 minutes in 3 per cent. nitric acid; then place for an hour in a mixture of alcohol, 1 volume, and water 2 volumes, and finally treat with stronger alcohol for 24 hours to separate the epidermis.

MÜLLER’S BERLIN BLUE FOR INJECTIONS.--Precipitate a concentrated solution of Berlin blue by means of 90 per cent. alcohol. The precipitate is very finely divided, whilst the fluid is perfectly neutral and much easier to prepare than that of Beale.

NEILSEN’S SOLUTION OF METHYL VIOLET.--Dissolve fuchsine, 1 part, in alcohol, 10 parts, and add a 5 per cent. watery solution of carbolic acid, 100 parts.

NEISSER’S DOUBLE-STAINING FOR SPORE-BEARING BACILLI.--Cover-glass preparations are immersed for 20 minutes in fuchsine aniline water (concentrated alcoholic solution of fuchsine, 11 C.c.; absolute alcohol, 10 C.c.; aniline water, 100 C.c.; then heat to 80° or 90° C.; next rinse in water, alcohol, or weak acid, according to the nature of the bacilli, counterstain with aqueous solution of methylene blue, rinse in water, dry and mount in balsam). The spores are stained red and the rest of the bacilli blue.

NISSL’S FUCHSINE STAIN FOR NERVE CELLS.--(1) Fresh material in pieces measuring 1 C.c. are hardened in a “chromic solution in 70 per cent. alcohol” for 2 days, then transferred to absolute alcohol for 5 days, and afterwards cut. Stain the sections singly in a saturated solution of fuchsine, warming in a deep watch-glass until vapours begin to be given off. Next plunge the section into absolute alcohol for 1 or 2 minutes, then place it on a slide, flood with clove oil, and when no more colour is given off, drain and mount in balsam.

OHLMACHER’S FORMALDEHYDE STAINING.--Formalin in a 2 to 4 per cent. solution is used as a mordant for tar colours. The tissues may be mordanted separately by treatment for 1 minute or longer, or the formalin may be added to the stain. Dissolve 1 Gm. of fuchsine in 10 C.c. of absolute alcohol, and add to 100 C.c. of 4 per cent. formalin solution. Or, add saturated alcoholic solution of gentian violet or methyl violet 5 B. to the formalin solution, in the proportion of 1:10. In the case of methylene blue, dissolve 1 G.m. in 100 C.c. of the formalin solution. Sections stain in half a minute, and are said to resist alcohol much more than if formalin were not used.

OPPITZ’S SILVER STAINING.--Reduction is very rapidly effected by placing the preparations for 2 or 3 minutes in a 0·25 to 0·5 per cent. solution of chloride of tin.

PAL’S HÆMATOXYLIN STAIN.--Dissolve 0·75 Gm. of hæmatoxylin in 90 C.c. of distilled water and 10 C.c. of absolute alcohol. Just before use add saturated solution of lithium carbonate in the proportion of 3 drops to each 10 C.c. of hæmatoxylin solution. (See Weigert.)

PAL’S HÆMATOXYLIN METHOD.--Proceed at first as in Weigert’s process for nerve fibre, omitting the copper bath, and stain in Pal’s hæmatoxylin solution (see above) for 5 or 6 hours. Then wash the sections in distilled water (containing a trace of lithium carbonate if the sections are not deep blue), next treat for 15 to 30 seconds with a 0·25 per cent. potassium permanganate solution, rinse in water, and decolourise in Pal’s bleaching solution. (If black spots appear replace in the permanganate solution, again bleach, and wash for 15 minutes in water.) The grey substance of the sections is decolourised in a few sections; the sections should then be well washed out, and may be double-stained with picro-carmine or acetic acid carmine (see Schneider), Magdala red, or eosine. The nuclei may be stained with alum carmine. Finally dehydrate, clear, and mount.

PAL-EXNER’S OSMIC ACID METHOD.--Spinal cord or brain in 0·25 inch cubes is immersed in 0·5 per cent. osmic acid solution for 2 days, the solution being changed each day; then wash in water, transfer to absolute alcohol, and imbed in celloidin or paraffin. Place sections as cut in glycerine, then wash in water, treat with potassium permanganate and Pal’s solution, as in Pal’s hæmatoxylin method, counter-stain with carmine, dehydrate, clear, and mount in balsam.

PLANT’S METHOD OF STAINING ACTINOMYCOSIS.--Sections are placed for 10 minutes in Gibbes’ magenta solution or carbolic fuchsine, at 45° C.; next they are rinsed in water and placed in saturated aqueous solution of picric acid, mixed with an equal volume of absolute alcohol, for 5 or 10 minutes; they are then washed once more, passed through 50 per cent. alcohol into absolute alcohol, cleared in cedar oil, and mounted in balsam.

RANVIER’S LEMON JUICE METHOD.--Soak pieces of fresh tissue in fresh lemon juice until transparent (5 to 10 minutes), then rapidly wash in distilled water, treat for 10 to 60 minutes with 1 per cent. gold chloride solution, again wash and expose to light in a bottle containing 50 C.c. of distilled water and 2 drops of acetic acid. Reduction is complete in 24 to 48 hours. If it is not desired to retain the superficial epithelium, reduction may be more completely effected in the dark, by treatment with formic acid (sp. gr. 1·2), diluted with 3 times its volume of water. The lemon juice in the above process may be replaced by an aqueous solution of citric acid (40 grains in each ounce).

RANVIER’S PICRO-CARMINE.--Carmine, 1 part; distilled water, 10 parts; solution of ammonia, 3 parts; mix and add of a cold saturated solution of picric acid 200 parts.

RENAUT’S HÆMATOXYLIC EOSINE.--Mix 30 C.c. of concentrated aqueous solution of eosine, 40 C.c. of saturated alcoholic solution of hæmatoxylin (which has been kept for some time and precipitated), and 130 C.c. of saturated solution of potash alum in glycerine (sp. gr. 1·26). Stand for 5 or 6 weeks in a partially covered vessel, protected from dust, until the alcohol is evaporated, and then filter. The filtrate can be diluted with glycerine if desired. Mount objects in this fluid diluted with 1 or 2 volumes of glycerine, or, stain separately for some days or weeks and mount in balsam, after washing in alcohol charged with a sufficient quantity of eosine.

RANVIER AND VIGNAL’S OSMIUM MIXTURE.--Fix tissues in a freshly-prepared mixture of equal volumes of 1 per cent. osmic acid and 90 per cent. alcohol, then wash out in 80 per cent. alcohol, next with water, and stain for 48 hours with picro-carmine or hæmatoxylin. This method has been applied to the histology of insects.

RENAUT’S GLYCERINE HÆMATOXYLIN.--To a saturated solution of potash alum in glycerine, add a saturated solution of homatoxylin in 90 per cent. alcohol drop by drop, so as to form a deeply coloured solution. Expose to daylight for a week, and then filter. This solution, like Renaut’s hæmatoxylic cosine, may be used for mounting unstained sections, which after some time absorb the colour from the liquid and become stained.

SAFRANINE.--Safranine, 0·5 Gm.; rectified spirit, 20 C.c.; distilled water, 80 C.c.

SCHÄFER’S ACID LOGWOOD SOLUTION is especially useful for certain structures, as tendon, cells, &c. It is thus prepared:--A 1 per cent. solution of acetic acid is coloured by the addition of 1·3 of its volume of logwood solution.

SCHÄFER’S ANILINE DYES, whether in aqueous or alcoholic solutions, give good results, and are prepared as follows:--Roseanilin or magenta (1 gr. to 1 oz. of alcohol), red; acetate of mauvein (4 gr., alcohol 1 oz., acid nitric 2 drops), blue; aniline black (2 gr., water 1 oz.), grey-black; Nicholson’s soluble blue (1-6 gr., alcohol 1 oz., and nitric 2 m.), blue. These stains should be used weak; and after sections are stained they should be passed through alcohol and oil of cloves as rapidly as possible; otherwise the colour will dissolve out before they can be mounted in balsam.

SCHULTZE (_Staining Bacilli_).--Stain sections and cover-glass preparations for some hours in aqueous methylene blue solution, differentiate in 0·5 per cent. acetic acid, dehydrate in alcohol, clear in cedar oil, and mount in balsam.

SCLAVO’S STAIN FOR FLAGELLA.--Leave the preparations for 1 minute in a solution of 1 Gm. of tannin in 100 C.c. of 50 per cent. alcohol; wash in distilled water; transfer for 1 minute to 50 per cent. phospho-molybdic acid; again wash, and stain for 3 to 5 minutes in a hot saturated solution of fuchsine in aniline water. Then wash in water, dry on filter paper, and mount in balsam.

SQUIRE’S PICRO-CARMINE.--(1) Dissolve 1 Gm. of carmine with a gentle heat in 3 C.c. of strong solution of ammonia, and 5 C.c. of distilled water, then add 200 C.c. of saturated aqueous solution of picric acid, heat to boiling, and filter. (2) Dissolve 10 Gm. of carmine in a solution of 1 Gm. of caustic soda in 1000 C.c. of distilled water; boil, filter and make up to 1000 C.c. with water. Mix the solution with an equal quantity of water, and add 1 per cent. aqueous solution of picric acid so long as the turbidity produced disappears on agitation.

SQUIRE’S BLUEING OF SECTIONS.--After staining with hæmatoxylin, treat for a few seconds with a solution of sodium bicarbonate (1:1000) in distilled water.

VALENTINE (_Fuchsine_).--Ether shaken with a solution containing fuchsine is coloured violet after adding ferrous iodide, but not before.

VICTORIA BLUE.--Victoria blue, 0·25 Gm.; rectified spirit, 20 C.c.; distilled water, 80 C.c.

WEDL’S ORSEILLE OR ORCHELLA STAIN.--Mix 5 C.c. of acetic acid, 20 C.c. of absolute alcohol, and 40 C.c. of distilled water; then add sufficient archil, from which excess of ammonia has been driven off, to form a dark reddish fluid.

WEIGERT’S HÆMATOXYLIN.--Dissolve 1 part of hæmatoxylin in 10 parts of absolute alcohol; then add 90 parts of distilled water and 1 part of aqueous solution (1:70) of lithium carbonate.

WEIGERT (_Gram’s Method_).--In this modification aniline is substituted for alcohol, in order to avoid prolonged washing with the latter, and the process is conducted on a slide. The section is placed on a slide, stained with a few drops of gentian violet aniline water, prepared as in Gram’s method, the excess of fluid removed, and a few drops of Gram’s solution applied. Subsequently remove the liquid by gently blotting it off, then wash the section by allowing aniline to flow’ backwards and forwards over it, and when colour ceases to come away, repeat the operation with xylol for about 1 minute, then mount in balsam.

WEIGERT (_Staining in Actinomycosis_).--Immerse sections for 1 hour in Wedl’s Orseille stain, then quickly rinse with alcohol and counterstain with gentian violet. If it be desired to stain the mycelium also, afterwards submit the sections to Weigert’s modification of Gram’s method. See page 335.

WEIGERT (_Staining Brain Tissue_).--Pieces of brain and spinal cord are hardened in bichromate solution, followed by alcohol, then imbedded in celloidin or gum. If imbedded in celloidin, the pieces are subsequently taken from the spirit in which they are immersed, and placed for one or two days in saturated aqueous solution of copper acetate, diluted with an equal bulk of water, the mixture being kept at about 40° C. Afterwards transfer the pieces to 80 per cent. alcohol until required for cutting. Or, the sections can be cut first, and then treated with copper acetate. To stain the sections, after being well washed in 90 per cent. alcohol, they are transferred to Weigert’s hæmatoxylin and left from a few hours to two days, according to the differentiation required. When opaque and of a deep blue-black colour, they should be well washed for two or three days in distilled water. Next decolourise for 0·5 to 2 hours in a solution of 2 Gm. of borax and 2·5 Gm. of potassium ferrocyanide in 200 C.c. of water. As soon as the grey and white substances are sharply defined, again wash the sections in water for half an hour, then dehydrate, clear, and mount in balsam.

WOODHEAD’S METHOD OF STAINING TUBERCLE BACILLI.--Take a small quantity of sputum rich in bacilli, and spread it out by pressure between two cover-glasses, so that a fairly thin film remains on each. Then carefully slip one over the other until they come apart. Thoroughly dry the covers, and pass them rapidly three times through the flame of a spirit lamp, care being taken not to scorch the film, then float them face downwards on the staining solution, which has been previously prepared and filtered into a watch-glass. The stain should consist of saturated alcoholic solution of basic fuchsine, 1 part; absolute alcohol or rectified spirit, 10 parts; carbolic acid solution (5 per cent.), 10 parts. Leave the preparations in the watch-glass for 12 to 24 hours, unless time is an object. In the latter case heat the fluid gently until vapour is given off, then drop the films on the surface, and leave them for 3 to 5 minutes only. Next transfer the covers to an aqueous solution of sulphuric acid (25 per cent.), and when decolourisation is complete, as evidenced by the pink colouration not returning when the specimens are plunged into a bowl of tap-water containing a single drop of ammonia solution, thoroughly rinse in the slightly alkaline water and counter-stain in an aqueous solution of methylene blue. Finally, wash in water, carefully dry and mount in Canada balsam. The bacilli should stand out as bright red rods on a blue background of cells.

ZIEHL-NEELSEN (_Staining Bacilli_).--Sections are removed from weak spirit into Neelsen’s carbolic fuchsine and left for 10 or 15 minutes; next decolourise in sulphuric acid (sp. gr. 1·84) or nitric acid (sp. gr. 1·42) diluted with 3 volumes of water, rinse in 60 per cent. alcohol, and wash in a large volume of water to remove the acid. Tubercle and leprosy bacilli are the only micro-organisms that can retain the stain after treatment with acid. If the presence of traces of nitrous acid in the nitric acid be suspected, Squire recommends the use of saturated aqueous solution of sulphanilic acid mixed with one-third its bulk of nitric acid. The sulphanilic acid destroys any free nitrous acid, which would otherwise exercise a bleaching action on the fuchsine-stained bacilli. The sections may be counterstained with a solution of 0·5 Gm. of methyl green (or 0·25 Gm. of methylene blue) in 20 C.c. of rectified spirit and 80 C.c. of distilled water. Finally dehydrate in absolute alcohol, clear in cedar oil, and mount in balsam.

APPENDIX D.

THE METRIC SYSTEM OF WEIGHTS AND MEASURES.

The initial unit of the Metric System is the Metre or unit of length, which represents one ten millionth part of the earth’s quadrant, or one forty-millionth part of the circumference of the earth around the poles. The multiples and sub-divisions of this and all the other units are obtained by the use of decimals, and for this reason the system is also known as the _decimal system_. The multiples are designated by the Greek prefixes, _deca_ = 10; _hecto_ = 100; _kilo_ = 1000; _myria_ = 10,000. For the sub-divisions Latin prefixes are employed, as follows: _deci_ = 1/10; _centi_ = 1/100; _milli_ = 1/1000. Thus for measures of length we have the following expressions, showing the abbreviations commonly employed, and the equivalents in the ordinary English standards of measurement--

1 Myriametre, Mm. = 10,000.0 M. = 6.2137 miles. 1 Kilometre, Km. = 1,000.0 M. = 0.6213 mile. 1 Hectometre, Hm. = 100.0 M. = 109.362 yards. 1 Decametre, Dm. = 10.0 M. = 32.8086 feet. 1 Metre, M. = 1.0 M. = 39.3704 inches. 1 Decimetre, dm. = 0.1 M. = 3.9370 " 1 Centimetre, cm. = 0.01 M. = 0.3937 " 1 Millimetre, mm. = 0.001 M. = 0.0393 "

From the unit of linear measure of metre is derived the unit of the measure of capacity or LITRE. This represents the cube of one-tenth part of a metre, or a cubic decimetre, and its multiples and sub-divisions with their corresponding equivalents in Imperial fluid measure are as follows:--

1 Myrialitre, Ml. = 10,000.0 L. = 2200.9667 imperial gallons.[91] 1 Kilolitre, Kl. = 1,000.0 " = 220.0966 " " 1 Hectolitre Hl. = 100.0 " = 22.0096 " " 1 Decalitre, Dl. = 10.0 " = 2.2009 " " 1 Litre, L. = 1.0 " = 35.2154 fluid ounces imperial. 1 Decilitre, dl. = 0.1 " = 3.5215 " " " 1 Centilitre, cl. = 0.01 " = 0.3521 " " " 1 Millilitre, ml. = 0.001 " = 0.0352 " " " or 1 Cubic Centimetre, ccm. = 0.001 L. = 0.0352 " " "

The unit of weight in the metric system is the GRAMME. This is also derived from the metre, and represents the weight of one cubic centimetre, of water, or the quantity of distilled water, at its maximum density, 4° C. (39·2° F.), which would fill the cube of one-hundredth part of a metre. The relative value of the gramme, together with its multiples and sub-divisions, as compared with the English standards of weight, may be seen from the following table:--

1 Myriagramme, Mg. = 10,000.0 Gm. = 22.0461 pounds. 1 Kilogramme, Kg. = 1,000.0 " = 2.2046 " 1 Hectogramme, Hg. = 100.0 " = 3.5273 ounces avoir. 1 Decagramme, Dg. = 10.0 " = 154.3235 grains. 1 Gramme, Gm. = 1.0 " = 15.4323 " 1 Decigramme, dg. = 0.1 " = 1.5432 " 1 Centigramme, cg. = 0.01 " = 0.1543 " 1 Milligramme, mg. = 0.001 " = 0.0154 "

The expression _micro-millimetre_ is used for microscopic measurements, and denotes the thousandth part of a millimetre. Of the measures of capacity, the terms most commonly employed are the litre and the cubic centimetre. Thus a decalitre may also be expressed as 10 litres, a centilitre as 10 cubic centimetres, etc. Of the metric weights the gramme and its fractional parts, with their respective prefixes, are much used in analytical work. The kilogramme is largely employed in commercial transactions, and is commonly abbreviated _kilo_.

As a comparison of the values of some of the more frequently employed expressions of the metric and English systems, the following may be found convenient for reference:--

1 mm. (millimetre) = 1/25 of an inch. 1 cm. (centimetre) = 2/5 of an inch. 1 inch = 25 millimetres or 2-1/2 centimetres. 1 mg. (milligramme) = 0.01543 grain (or approx. 1/64 grain). 1 gm. (gramme) = 15.4324 grains. 1 Kg. (“Kilo” or kilogramme) = 2 lbs. 3-1/4 ozs. av. 1 pound avoir. = 453,592 grammes. 1 ounce avoir. = 28,350 grammes. 1 grain = 0.06479 gramme or 64.79 milligrammes. 1 cc. (cubic centimetre) = 16.9 minims Imperial measure. 1 L. (litre) = 35.21 fluid ounces Imperial measure, or 33.815 fluid ounces Wine measure. 1 fluid ounce Imperial measure = 28.350 grammes. 1 pint Imperial measure = 567.0 grammes. 1 gallon Imperial measure = 4.536 litres, or 10 lbs. avoir. of pure water at 62° F. and under an atmospheric pressure of 30 inches of mercury.

It may be well to bear in mind that on the Continent liquids are always weighed, not measured.

APPENDIX E.

COMPARISON BETWEEN THE CENTIGRADE AND FAHRENHEIT THERMOMETERS.

F. C. 212 100 200 93.3 150 65.6 112 44.4 110 43.3 108 42.2 106 41.1 105 40.5 104 40 103 39.4 102 38.9 101 38.3 100 37.8 99 37.2 98 36.7 96 35.6 94 34.4 92 33.3 90 32.2 88 31.1 86 30 84 28.9 82 27.8 80 26.7 78 25.6 76 24.4 74 23.3 72 22.2 70 21.1 68 20 66 18.9 64 17.8 62 16.7 60 15.6 58 14.4 56 13.3 54 12.2 52 11.1 32 0 25 -3.9

INDEX.

Abbé on microscopical vision, 37

Abbé’s apertometer, 59

---- condenser, 176

---- stereoscopic eye-pieces, 64

---- test-plate, 164

Aberration, chromatic, 25

---- of the eye, chromatic, 33

---- spherical, 23

Abraxas grossulariata, 598

Absolute alcohol as a hardening reagent, 287

Acaras domesticus, 625

Accessories of the microscope, 197

Achromatic condenser, Beck’s, 180

---- ---- Gillett’s, 173

---- ---- method of using, 190

---- ---- Powell’s, 178

---- ---- Ross’s, 176

---- ---- Smith & Beck’s, 173

---- ---- Watson’s, 177

Achromatic objective, the, 152

Acineta, 495

Actiniæ, 527

Actinophrys-sol, 489

Adams’s book on the microscope, 8

Adipose tissue, 644

Ædogoniaceæ, 409

Aerobic spores, 399

Agar-agar, to prepare nutrient, 330

Air bubbles, 348

Alcyonella, 534

Algæ, 399

---- media for preserving, 343

---- red, 413

Alvarez’s discovery of bacillus, 392

Amici prism, the, 190

Amœba, 480

Amphibian changes, 669

Amphistoma, 570

Amyot finder, the, 205

Anacharis alsinastrum, 419

Anemones, sea, 526

Angle of vision, 72

Anguillula, 567

Animal structures, staining, 292

Annulosa, 562

Antennæ of insects, 584

Antenna of silkworm moth, 605

Anthrax bacillus, 369

Anthrozoa, 523

Apertometer, Abbé’s, 59

Aperture, definition of, 45

---- measurement of, 57

---- numerical, 57

---- table, 58

Aphides, 587

Aphrophora bifasciata, 618

Apis mellifica, 598

Aplysiidæ, 549

---- dipilans, 549

Apparatus for mounting, 352

Appendices, 673

Arachnidæ, 618

Aragonite, 232

Arcella, 483

Arenicola, 577

Argyroneta aquatica, 621

Artemiæ, 581

Arteries, 622

Artery-needle, 303

Arthropoda, 583

Arthrospores, 366

Ascidian, 669

Astroides calyculcaris, 529

Babè’s method of staining bacteria, 334

Bacillus, anthrax, 369

---- of plague, 372

---- ---- in rat’s blood, 372

---- splenic fever, 369

---- typhoid, 370

Bacteria, 317

---- aerobic, 399

---- classification of, 373

---- Cohn on multiplication of, 367

---- cultivation of, 327

---- ---- in tubes, 331

---- ---- on plates, 331

---- faculties of, 373

---- in butter, 393

---- in cheese, 393

---- in milk, 393

---- in sections of tissue, 337

---- invasion of potato-tubers by, 398

---- microscopical examination of, 333

---- phosphorescent, 373

---- reproduction of, 365

---- size of, 365

---- staining, 334

---- Winogradsky’s investigations of, 398

Bacterial action in tanning skins, 393

---- fermentations, 391

Bacteriological investigations, apparatus for, 318

---- ---- mounting media, 320

---- ---- reagents used, 320

---- microscope, the, 135

Bacteriology of the dairy, 393

Baker’s advanced student’s microscope, 123

---- collecting stick, 350

---- histological microscope, 125

---- micro-photographic apparatus, 217

---- microscope lamp, 191

---- microscopes, 120

---- Nelson condenser, 184

---- ---- model microscope, 120

---- objectives, 168

---- student’s condenser, 184

Baird, Dr., on daphnia, 581

Barnacle, 539

Bartley’s warm-stage, 281

Batrachospermæ, 409

Beck’s binocular dissecting microscope, 101

---- ---- National microscope, 99

---- complete microscope lamp, 202

---- compressor, 275

---- disc-holder, 198

---- large Continental model microscope, 98

---- microscopes, 95

---- objectives, 167

---- pathological microscope, 95

---- Star microscope, 101

Beggiatoa, 400

Benjamin Martin’s microscope, 5

Beroidæ, 519

Biaxial crystals, 228

Bilharzia hæmatobra, 573

Binocular microscope, advantage of, 69

---- ---- Carpenter on, 69

---- ---- Nachet’s, 62

---- ---- Pillischer’s, 128

---- ---- Riddell’s, 62

---- ---- Stephenson’s erecting, 71

---- ---- Wenham’s, 65

---- vision, 60

Bismarck-brown for staining protoplasm, 306

Bivalves, 538

Bleaching process, 315

Blood as a test, 263

---- circulation of, in frog’s foot, 665

---- ---- ---- tadpole, 665

---- corpuscles, 638

---- ---- double staining, 295

---- ---- size of, 640

---- crystals, 641

---- spectrum, 252

Bombay plague, 371

Bone, 658

---- of fish, 661

---- of reptilia, 660

---- structure of, 659

Borax, 231

Boring sponges, 513

Botterill’s live-trough, 276

Brachiopoda, 538

Branchipodidæ, 580

Brewster’s microscope, 11

Brittleworts, 427

Browning-Huggins micro-spectroscope, 245

Browning’s pocket lens, 76

Bryophyta, 444

Bryozoa, 531

Buchner’s experiments on yeast, 389

Bull’s-eye condensing-lens, 199

Butter, bacteria in, 393

Butterfly’s tongue, 605

---- wings, 610

Calc-spar, 231

Cambridge rocking microtome, 290

Camera lucida, the, 207

---- ---- the Abbé, 208

---- ---- the Wollaston, 207

---- Swift’s horizontal, 213

Canada balsam, 293

Carbonate of lead, 232

Carmine as a nuclear stain, 312

Cartilage, 655

Catheart’s freezing microtome, 291

Cedar oil, use of, 171

Cell, definition of, 358

Cell-making turn-table, Walmsley’s 340

Cells, epithelial, 636

---- for living objects, 276

---- for mounting, 340

---- live, 277

Cellulose, 357

---- staining, 314

Cements, 347

---- list of, 676

Centipedes, 578

Cercariæ, 571

Cereal parasites, 381

Chætophoraceæ, 409

Chara, fructification of, 417

---- mounting, 347

---- vulgaris, 415

Characeæ, 415

Cheese, bacteria in, 393

---- mite, 625

Chilinidæ, 551

Chitonidæ, 545

Chloride of gold as stain, 297

---- of palladium as stain, 298

Chromatic aberration, 25

---- ---- of the eye, 33

Chromic acid as hardening reagent, 288

Ciliata, 498

Circulation of the blood, 665

Cistula catenata, 558

Cladocera, 580

Clavatella prolifera, 521

Clearing agents, list of, 676

Clepsinidæ, 576

Clionæ, 513

Closterium, 424

---- lunula, 425

Cnidaria, 519

Cockchafer’s eye, 590

Coddington lens, the, 76

Codosiga, 497

Cœlenterata, 515

Cohn on multiplication of bacteria, 367

Cole’s direction for section cutting, 285

---- section-cutting microtome, 289

Collecting stick, Baker’s, 350

Collection of objects, 349

Compound microscope, 78

Compressor, Beck’s, 275

Compressorium, 274

---- Ross’s, 275

---- Rousselet’s, 275

Concave lenses, 23

---- surfaces, 17

Condenser, Abbé’s, 176

---- Baker’s Nelson, 184

---- ---- student’s, 184

---- Beck’s achromatic, 180

---- Gillett’s achromatic, 173

---- method of using, 190

---- Powell’s achromatic, 178

---- Ross’s achromatic, 176

---- Smith & Beck’s achromatic, 173

---- ---- substage, 193

Condenser, Swift’s, 183

---- Watson’s achromatic, 177

---- ---- parachromatic, 182

---- Webster-Collins, 186

---- Wenham’s immersion, 189

---- ---- parabolic, 186

Confervaceæ, 408

Conjugate foci, 17

---- real and virtual, 21

Continental microscopes, 130

Contrast stains, 313

Convex lens, 18

Copepoda, 580

Corals, 515, 525

---- true, 528

---- typical forms of, 533

Correction collar, Lister’s, 155

Coryne stauridia, 534

Cotton fibres, 474

Cover glass gauge, Zeiss’s, 165

Crinoids, 542

Critical angle, 14

Crookshank’s incubator, 324

---- method of staining bacteria, 335

Crustaceæ, 578

Crystals, formation and polarisation of, 239

Ctenophora, 518

Cuckoo-spit, 618

Culex pipiens, 596

Cultivation of bacteria, 327

---- of micro-organisms, 327

Cutleria dichotoma, 413

Cutting sections of hard woods, 316

Cuttle-fish, 556

Cyclops, 580

Cyclosis, phenomenon of, 359

Cyclostomata, 537

Cyclotus translucidus, 558

Cydippidæ, 518

Cymba olla, 557

Cymothordæ, 580

Dairy, bacteriology of, 393

Daphnia, enemies of, 581

---- ephippial eggs of, 580

Daphnia pulex, 580

De Bary’s investigations in parasitism, 395

Decalcifying and bleaching agents, list of, 677

Decalcifying solution as hardening reagent, 288

Demodex folliculorum, 627

Dental structure, 652

Dermestes lardarius, 627

Dermis, the human, 647

Desmidiaceæ, 420

---- reproduction of, 423

Diamond microscope, Pritchard’s, 9

Diaphragm, the, 194

---- the iris, 176

Diatomaceæ, 420, 427

---- fossilised, 437

---- Max Schultze’s researches, 430

---- where found, 428

Diatoms, mounting medium, 343

---- movements of, 431

Didymoprium grevelli, 420

Difflugia, 482

Digestive system of insects, 587

Dipping-tubes, 279

Disc-holder, Beck’s, 198

Dissecting-knives, 284

Dog-tick, 624

Double convex lens, 19

Draparnaldia glomerata, 409

Draw-tube, Swift’s, 116

---- Watson’s, 104

Drone fly, 594

Dytiscus marginalis, 607

Echinococcus, 565

Echinodermata, 539

Eggs of insects, 612

Elementary optics, 12

Embedding fluids, list of, 678

---- in paraffin wax, 285

Entomological specimens, mounting, 341

Entozoa, 562

Eosin stain, 315

Eozoon, 492

Epeira diadema, 619

Epidermis of plants, 455

Epithelial cells, 636

Epithelium, mounting, 295

Equisetaceæ, 449

Ergot of rye, 382

Eristalis tenax, 594

Erysiphe Tuckeri, 380

Eudorina, 406

Euglypta, 482

Eurotium repens, 383

Exposure table for photo-micrography, 213

Eye, chromatic aberration of the, 33

---- of cockchafer, 590

---- of fly, 588

---- of whirligig beetle, 608

---- the human, 30

Eye-piece, Abbé’s stereoscopic, 64

---- compensating, 147

---- ---- Zeiss’s, 147

---- Huyghenian, 139

---- Jackson’s micrometer, 143

---- Ramsden, 142

---- ---- micrometer, 145

---- Ross’s, 68

---- Wenham’s double, 63

---- Zeiss’s, 147

Eye-pieces, 139

---- achromatic, 149

---- magnifying powers of, 169

---- projections, 150

---- to clean, 259

Eyes of insects, 584

Favellidium, 415

Feet of insects, observation of, 604

Felices, 446

Fermentation experiments, 361

Fermentations, bacterial, 391

Ferns, 446

---- development of, 446

Fibro-cartilage, 657

Fibrous tissue, 642

---- ---- mounting, 296

Filaria sanguinis hominis, 568

Finder, the, 204

---- the Amyot, 205

---- the Maltwood, 204

---- the Okeden, 205

---- Pantacsek’s, 205

Fission formation, 365

Fixing solutions, list of, 678

Flabellum, 528

Flagella, staining of, 336

Flagellate infusoria, 495

Flatness of field, 262

Flax, fibres of, 474

Flea, 629

Florideæ, 413

Flowering plants, 451

Fluke, the, 569

Flustra, 532

Fly, eye of, 588

---- foot of, 602

Focal length of lenses, 22

Focus, method of finding, 271

Foot of fly, 602

Foraminifera, 483

Forceps, 283

---- for mounting, 294

---- stage, 198

Formation and polarisation of crystals, 239

Fossil plants, 475

Fossilised diatomaceæ, 438

Freezing agents, list of, 678

---- microtome, Cathcart’s, 291

---- ---- directions for using, 291

Frog-bit, 418

---- plate, 277

Froth-fly, 618

Fungi, industrial uses of, 391

Fungoid diseases, 374

Fungus on plants, 376

---- root, benefit to trees from, 396

---- sewage, 400

---- where found, 379

Gall-fly, 596

Gapeworm, 572

Gelatine, to prepare nutrient, 328

German yeast, 388

Gillett’s achromatic condenser, 173

Globigerina, 486

Glycerine agar-agar, 330

---- jelly, to make, 297

Gnat, 596

Gnathia, 579

Goniometer, Dr. Leeson’s, 150

Gorgoniidæ, 530

Gosse on noctiluca, 496

Gram’s method of staining bacteria, 335, 338

Grant’s researches on sponges, 507

Gregarinæ, 482, 563

Gromia, 484

Grove’s recommendations for mounting, 299

Gyrinus, eye of, 608

---- leg of, 608

Hæmatoxylin stain, 312

Hairs, structure of, 648

Haliotis splendens, 559

---- tuberculatus, 557

Hansen’s investigations of yeast, 387

Hard structures, mounting, 307

---- woods, cutting sections of, 316

Hardening agents, list of, 677

---- ---- absolute alcohol, 287

---- ---- chromic acid as, 288

---- ---- decalcifying solution as, 288

---- ---- methylated spirit as, 288

---- ---- Muller’s fluid as, 288

---- ---- potassium bichromate, 288

Hardening reagents, 287

---- tissue, 283

Hartea elegans, 535

Heliozoa, 489

Helix absoluta, 558

---- pomatia, 558

Hepaticæ, 442

Hexactinia, 526

Hirudina medicinalis, 576

Hirudinidæ, 575

His’s method of staining bacteria, 334

Holland’s simple microscope, 75

Holman’s life slide, 277

---- moist chamber, 277

---- syphon slide, 278

Holothurioidea, 543

Honey bee, 598

Horse-tails, 449

House fly, eye of, 588

---- proboscis of, 591

---- tongue of, 592

Human eye, the, 30

---- hair as a test, 269

Huyghenian eye-piece, 139

Hydra, 516

---- fasca, 516

---- stinging, 519

---- viridis, 516

Hydractinia echinata, 523

Hydroid polyps, colony of, 537

Hydrozoa, 515

Ianthinidæ, 550

Iceland spar, 221

Illumination arrangements of the microscope, 673

---- Mercer on, 673

Incubation, apparatus for, 322

---- test for, 263

Incubator, Crookshank’s, 324

Incubators, 324

Indigo plant, 392

Infusoria, 493

Infusorial life, 349

Injecting, directions for, 304

---- insects, 306

---- lower animals, 305

---- mollusca, 305

---- small animal bodies, 302

---- ---- ---- ---- syringe for, 302

---- with different colours, 304

Injections, to prepare, 303

---- ---- subjects for, 303

Injurious insects, 632

Insects, 578, 583

---- antennæ of, 584

---- digestive systems, 586

---- distinctive character of, 583

---- eggs of, 612

---- eyes of, 584

---- injecting, 306

---- injurious, 632

---- mouths of, 584

---- muscles of, 585

---- reproduction of, 587

---- respiratory system of, 607

---- thorax of, 585

---- wings of, 609

Interpretation, errors of, 263

Iris diaphragm, 176

Isthmia enervis, 436

Ixodidæ, 622

Ixodes ricinus, 624

Jackson’s micrometer eye-piece, 143

Jelly-fish, 519, 523

Jungermannia, 442

Koch’s method of staining flagella, 336

Lamp, Baker’s microscope, 191

---- Beck’s complete microscope, 202

---- shells, 539

---- the microscope, 201

---- Watson’s microscope, 203

Lard, embedding in, 285

Larvæ of sea-anemones, 529

Lathe for cutting sections of teeth, 308

Laticiferous tissues, 466

Leaf tissue, 466

Leeson’s goniometer, 150

Leeuwenhoek’s microscope, 4

Leitz’s dissecting microscope, 132

---- microscopes, 132

Lens, bull’s-eye condensing, 199

---- Steinheil’s aplanatic, 77

---- the Coddington, 76

Lenses, concave, 23

---- convex, 18

---- double convex, 19

---- focal length of, 22

---- forms of, 18

---- meniscus form of, 24

---- optical centre of, 20

---- plano-convex, 19

Lepas, 539

Lepisma saccharina, 612

---- scales of, as test, 264

Leptothrix buccalis, 400

Lichenaceæ, 439

Lichens, 439

---- erratic, 441

Lieberkühn’s microscope, 4

Lieberkühn, the, 198

Light, polarisation of, 219

Limax maximus, 558

---- rufus, 558

Limnæan, teeth of, 554

Limnæidæ, 551

Limnæus stagnalis, 551

Lingula pyramidata, 538

Lingulidæ, 538

List of salts, 240

Lister’s correction collar, 155

---- flasks, 322

---- microscope, 81

---- object glass, 154

Live-cages, 274

Live-cells, 277

Live-trough, Botterill’s, 276

Liverworts, 442

Lobosa, 482

Löffler’s method of staining flagella, 336

Logwood, staining by, 293

Lophopus crystallinus, 535

Lyda campestris, 598

Lymph corpuscles, 638

Maddox growing stage, the, 280

Magnifying powers of eye-pieces and objectives, 169

Maltwood finder, the, 204

Maple aphis, 617

Mapping spectra, 253

Marchantia polymorphia, 442

Martin’s microscope, 5

Marzoni’s objective, 152

Mayall’s illuminator, 184

---- mechanical stage, 124

Medusæ, 515, 521

---- a colony of budding, 537

Melicerta ringens, 505

Melolontha vulgans, eye of, 590

Meniscus form of lens, 24

Mercer on illumination, 673

Mesoglæa, 525

Mesoglia vermicularis, 410

Methylated spirit as hardening reagent, 288

Metric system of weights and measures, 687

Micrometer, Ramsden’s, 145, 206

---- the stage, 206

Micrometers, 205

Micro-organisms, 373

---- cultivation of, 327

Micro-photography, 210, 674

---- Baker’s apparatus for, 217

---- exposure table, 213

---- Pringle’s apparatus, 217

---- rules for, 214

---- Stringer-Watson’s apparatus for, 674

---- Swift’s apparatus for, 213

Microscope, accessories of the, 197

---- Baker’s advanced student’s, 123

---- ---- histological, 125

---- ---- Nelson model, 120

---- Beck’s binocular dissecting, 101

---- ---- ---- National, 99

---- ---- large Continental model, 98

---- ---- pathological, 95

---- ---- Star, 101

---- binocular, Pillischer’s, 128

---- ---- Wenham’s, 65

---- Carpenter on binocular, 69

---- compound, 78

---- early history of, 1

---- Holland’s simple, 75

---- Hooke’s water, 2

---- illumination arrangements of the, 673

---- invention of, 2

---- lamp, the, 201

---- ---- Baker’s, 191

---- ---- Beck’s, 202

---- ---- Watson’s, 203

---- Leitz’s dissecting, 132

---- Leeuwenhoek’s, 4

---- Lieberkühn’s, 4

---- Lister’s, 81

---- manipulation and mode of using the, 258

---- Martin’s, 5

---- Nachet’s, 133

---- ---- binocular, 62

---- Pillischer’s binocular, 128

---- ---- International, 126

---- Pillischer’s “Kosmos,” 128

---- Powell & Lealand’s, 85

---- ---- student’s, 88

---- Pritchard’s diamond, 9

---- Riddell’s binocular, 62

---- Ross’s “Eclipse,” 89

---- ---- New Industrial, 90

---- Ross-Jackson, 82

---- Ross-Jackson-Zentmayer, 83

---- Ross-Zentmayer, 91

---- Rousselet’s tank, 126

---- simple, 30, 72, 77

---- simple pocket, 73

---- Sir David Brewster’s, 11

---- Stephenson’s erecting binocular, 71

---- Swift’s advanced student’s, 118

---- ---- bacteriological, 116

---- ---- four-legged, 114

---- ---- histological student’s, 116

---- the bacteriological, 135

---- Watson’s bacteriological, 108

---- ---- Edinburgh student’s, 102

---- ---- histological, 107

---- ---- petrological, 111

---- ---- portable, 110

---- ---- Van Heurck’s, 108

---- Wenham’s binocular, 65

---- ---- radial, 90

---- Wollaston’s simple, 74

---- Zeiss’s, 130

Microscopes, Baker’s, 120

---- Beck’s, 95

---- Continental, 130

---- Leitz’s, 132

---- Pillischer’s, 126

---- Ross’s, 88

---- Swift’s, 113

---- Watson’s, 102

Microscopic forms of life, 353

---- vision, principles of, 45

---- ---- theory of, 37

Micro-spectroscope, the, 243

Micro-spectroscopic eye-piece, the Sorby-Browning, 247

---- method of using, 250

---- the Browning-Huggins, 245

Microtome, Cambridge rocking, 290

---- Cathcart’s freezing, 291

---- Cole’s section-cutting, 289

---- method of using, 289

Milk, bacteria in, 393

Millipedes, 578

Mineral and geological kingdoms, 670

Mirror, manipulation of, 260

---- the, 195

Mite, cheese, 625

Mites and ticks, 622

Moist stage, 280

Molecular rotation, 238

Mollusca, 545

---- injecting, 305

---- shell of, 558

Monads in rat’s blood, 372

Monoxenia, 523

Moss-animals, 531

Mosses, 443

Moulds, 380, 381

Mounting apparatus, 352

---- cells for, 340

---- chara, 347

---- entomological specimens, 341

---- epithelium, 295

---- fibrous tissue, 296

---- forceps, 294

---- hard structures, 307

---- media, list of, 678

---- nerve tissue, 296

---- non-striated muscle, 296

---- objects, materials required, 339

---- rock sections, 309

---- spring clip for, 296, 342

---- teeth sections, 308

---- vegetable tissues, 310

Mouse, hair of, 650

Mouth, leptothrix, 400

Mouths of insects, 584

Müller’s fluid, a hardening reagent, 288

Musca domestica, 588

Musci, 443

Muscidæ, 588

Muscles of insects, 585

Muscular fibre, 644

---- ---- mounting, 296

Mycetoma, 378

Mycetozoa, 482

Mycorhiza, 396

Nachet’s binocular microscope, 62

Nails, structure of, 648

Navicula, 427

Neckera antiphyretica, 445

Needles for teasing out sections, 286

Nematoid worms, 556

Nerve tissue, mounting, 296

Nicol prism, 220

Nitella, 418

Nitrate of silver as stain, 297, 298

Noctiluca, 496

Non-striated muscle, mounting, 296

Nose-pieces, 203

Nuclear stains, 311

---- ---- carmine, 312

---- ---- hæmatoxylin, 312

Nudibranchiata, 547

Nutrient agar-agar, to prepare, 330

---- gelatine, to prepare, 328

---- jelly, to inoculate with bacteria, 331

Object glass, Lister’s, 154

---- to clean, 260

Objective, achromatic, 152

---- changers, 203

---- Powell & Lealand’s oil immersion, 166

Objectives, Baker’s, 168

---- Beck’s, 167

---- English and German, 159

---- high power, 171

---- magnifying powers of, 169

---- Pillischer’s, 169

---- Ross’s, 166

---- Swift’s, 168

---- Watson’s, 167

Objects, collection of, 349

Oblique illumination, 186

Oidium albicans, 384

Okeden finder, the, 205

Onion, raphides of, 472

Opisthobranchiata, 548

Optical centre of lenses, 20

Optics, elementary, 12

Oscillariaceæ, 407

Osmic acid as stain, 298

Palates of gastrapods, 556

Palmellaceæ, 407

Palmoglæa macrococca, 401

Pandorina morum, 406

Parabolic reflector, 188

Paraffin wax, embedding in, 285

Parasites, cereal, 381

---- sponge, 512

---- vine, 380

Parasitic diseases of plants, 372

---- fungi of men and animals, 383

Parasitism, De Bary’s investigations in, 395

Patella radiata, 556

Pearls, structure of, 559

Pectinibranchs, 550

Pediastreæ, 422

Pedicellanæ, 543

Peltogaster curvatus, 539

Penetration in objective, 261

Pennatulidæ, 530

Pentacrinoids, 540

Pepperworts, 451

Peronospora viticola, 381

Petiole, 466

Phanerogamiæ, 451

Phanerogams, structure of, 453

Phloem of plants, 454

Pholadidæ, 545

Phomauvicola, 381

Photo-micrography, 210

---- apparatus for, 213

---- Baker’s apparatus for, 217

---- exposure table, 213

---- rules for, 214

---- Swift’s apparatus for, 213

Phylactolæmata, 533

Phylloxera vastatrix, 381

Physalia, 521

Physidæ, 551

Picro-carmine as stain, 299

Pigment cells, 446

Pillischer’s binocular microscope, 128

---- International microscope, 126

---- “Kosmos” microscope, 128

---- objectives, 169

Pinna ingens, 559

Pinnulariæ, 434

Pipette, 319

---- Pasteur’s bulb, 322

Plague, bacillus of, 370

---- the Bombay, 371

Planariæ, 575

Plano-convex lens, 19

Plants, epidermis of, 455

---- fibro-vascular system of, 460

---- flowering, 451

---- fossil, 475

---- ground tissue, system of, 458

---- hairs, 457, 473

---- parasitic diseases of, 374

---- raphides in, 472

---- reproductive organs of, 467

---- spores of parasitic fungus on, 376

---- structure of, 453

---- tissue systems of, 454

---- vascular system of, 464

Plasmodia, 482

Pleurobranchus aurantiacus, 548

---- plumula, 557

Pleurosigma angulatum, 429

---- as a test, 267

---- attenuatum, 429

Plumularia, 521

Pocket lens, Browning’s, 76

---- Coddington’s, 76

Podura-scale test, 268

---- villosa, 611

Polarisation apparatus, 223

---- of light, 219

---- prism, 220

---- ---- method of employing, 224

---- rotation of plane of, 231

Polarised crystal of quinidine, 235

Polarising apparatus, Watson’s, 224

Pollen grains, 467

---- ---- method of mounting, 467

Polycystina, 489

Polymorphina, 486

Polypomedusæ, 519

Polytrichum undulatum, 445

Polyzoa collecting, 350

Pond-snails, 551

Porifera, 506

Portable microscope, Watson’s, 110

Potassium bichromate as hardening reagent, 288

---- nitrate, crystal of, 232

Powell & Lealand’s microscope, 85

---- oil immersion objective, 166

---- student’s microscope, 88

---- formula for objective, 166

Preparing tissue, 283

Primordial cell, 357

Principal focus, 18

Pringle’s micro-photography apparatus, 217

Prism, 15

---- Nicol’s, 220

Pritchard’s diamond microscope, 9

Proboscis of house fly, 591

Proteolepas, 539

Protococcus invalis, 380

---- pluvialis, 401

Protoplasm, 356

---- staining living, 306

Protozoa, 478

Puccinia graminis, 375

Pyrocystis, 496

Quartz, 231

Quekett on Martin’s microscope, 6

Quinidine, crystals of, 235

Radiolaria, 490

Ramsden eye-piece, 142

---- micrometer eye-piece, 145

Raphides in plants, 472

Rayleigh’s theory of formation of optical images, 44

Reflection, 16

Reflector, Sorby’s, 199

Refraction, 13

---- through prism, 15

Reproductive organs of plants, 467

Resolving power, 262

Retiform tissue, 644

Rezner’s mechanical finger, 343

Rhizocarpeæ, 451

Rhizopoda, 482

Riddell’s binocular microscope, 62

Rochelle salt, 232

Rock limpet, 556

---- sections, mounting, 309

Ross’s achromatic condenser, 176

---- compressorium, 275

---- Eclipse microscope, 89

---- eye-pieces, 68

---- microscopes, 88

---- object glass, 154

---- objectives, 166

Ross-Hepworth arc lamp, 218

Ross-Jackson microscope, 82

Ross-Jackson-Zentmayer microscope, 83

Ross-Zentmayer microscope, 91

Rotatoria, mounting, 345

Rotifera, 502

Rousselet’s compressorium, 275

---- method of mounting rotatoria, 345

---- tank microscope, 126

Rye, ergot of, 382

Saccharomyces cerevisiæ, 384

---- ellipsoideus, 385

---- mycoderma, 384

Saccharomycetes, industrial uses of, 391

Salts, list of, 240

Saprolegnia ferox, 411

Sarcode, 357

Saw-fly, 598

Scalariidæ, 550

Scales of butterfly’s wings, 610

Scapander ligniarius, 557

Schäfer’s warm-stage, 282

Scyphomedusæ, 523

Sea-anemone, larvæ of, 529

Sea-anemones, 526

Sea-cucumber, 540, 543

Sea-hares, 549

Sea-mats, 532

Sea-urchin, 540

Sea-weeds, 409

Section cutting, 283

---- ---- Cole’s directions for, 285

Section-cutting microtome, Cole’s, 289

---- lifters, 319

---- scissors, 283

Sections of hard wood, cutting, 316

Selenite, 225

Sepia officinalis, 556

Sertularia, 521

Shadbolt’s turn-table, 295

Sheep-tick, 624

Shell, structure of, 558

---- formation in limnæa, 552

Sieve-tubes, 465

Silk filaments, 474

Silk-worm, 605

Silk-worms, disease of, 363

Silver-side reflector, 198

Simple microscopes, 30, 72, 77

Siphonophora, 521

Sirax gigas, 597

Skin, 646

Smith & Beck’s achromatic condenser, 173

Snow crystals, 237

Sorby-Browning micro-spectroscopic eye-piece, 247

Sorby’s reflector, 199

Spectroscope, cells for use with, 251

---- the, 244

Spectrum of chromule, 255

Sphæroplea annulina, 409

Sphærosira volvex, 406

Sphagnaceæ, 446

Spherical aberration, 23

Spiders, 619

Spirilla, 368

Spiro-bacteria, 368

Splenic fever bacillus, 369

Sponges, 506

---- boring, 513

---- Geodia Barretti, 510

---- Grant’s researches on, 507

---- hyalonema, 512

---- parasite on, 512

---- reproduction of, 510

Spongia coalita, 507

Spongiadæ, 506

Spore of parasitic fungus on plants, 576

Spores, 366

Spores, aerobic, 399

---- endogenous, 366

---- staining of, 336

Spring clip for mounting, 296, 342

Stage, Bartley’s warm, 281

---- forceps, 198

---- Maddox growing, 280

---- Mayall’s mechanical, 124

---- moist and warm, 280

---- Schäfer’s, 282

---- Stricker’s, 282

---- Watson’s semi-mechanical, 107

Stain, eosin, 315

Staining animal structures, 292

---- bacteria, 334, 338

---- by logwood, 293

---- cellulose, 314

---- double, 293

---- double and treble, 300

---- living protoplasm, 306

---- of flagella, 336

---- of spores, 336

---- tissue, 283

Stains and staining methods, list of, 679

Stains, chloride of gold, 297

---- chloride of palladium, 298

---- contrast, 313

---- double and treble, 300

---- nitrate of silver, 297, 298

---- osmic acid, 298

---- picro-carmine, 299

---- single, 298

Starch, 238

---- granules, 469

---- ---- of arrowroot, 470

---- ---- of potato, 470

---- ---- of wheat, 470

Star-fish, 540

Steinheil’s aplanatic lens, 77

Stentors, 501

Stephanoceros, 504

Stephanosphæra pluvialis, 403

Stephenson’s erecting binocular microscope, 71

Stereoscope, the, 60

Stereoscopic binocular vision, 60

Sterilised instruments, 321

Sterilisers, 324

---- Hearson’s, 325

---- steam, 325

---- ---- Dr. Koch’s, 325

Sting of bee, 596

---- of wasp, 596

Stock-bottle, 279

Stomata of iris, 456

---- water pores, 457

Stone-lilies, 542

Stonewort, 415

Stricker’s warm stage, 282

Stringer’s apparatus for micro-photography, 674

Stylonychia mytilus, 500

Stylopidæ, 628

Substage condenser, 193

Subterranean fungi, 397

Sun-animalcules, 489

Swift’s advanced student’s microscope, 118

---- bacteriological microscope, 116

---- draw-tube, 116

---- four-legged microscope, 114

---- histological student’s microscope, 116

---- horizontal camera, 213

---- illuminating apparatus, 183

---- microscopes, 113

-- objectives, 168

Tables, aperture, 58

Tænia, 564

Tanning skins, 393

Tardigrada, 631

Teasing out sections, needles for, 286

---- ---- ---- under condensed light, 287

Teeth, 652

---- lathe for cutting sections of, 308

---- method of cutting sections of, 308

---- mounting, 308

Tenent-hairs, 603

Terebella littoralis, 577

Terebratulata rubicuna, 559

Testacella maugei, 556

Test for illumination, 263

Test object, blood as a, 263

Test object, human hair as, 269

---- ---- lepisma as, 264

---- ---- pleurosigma, 267

---- ---- podura-scale, 268

Test-plate, Abbé’s, 164

Threadworm, 566

Thorax of insects, 585

Thuricola valvata, 500

Tick, dog, 624

---- sheep, 624

Ticks, 622

Tissue, adipose, 644

---- bacteria in sections of, 337

---- fibrous, 642

---- hardening, 283

---- preparing, 283

---- retiform, 644

---- staining, 283

---- systems of plants, 454

Tongue of butterfly, 605

---- of house fly, 592

---- of wasp, 595

Tooth substance, 654

Topaz, 231

Tourmaline, 225

Trematode worms, 569

Trichina spiralis, 567

Trichomes of plants, 457

Troughs, 274

Truffle, 397

Tuber cibarium, 397

Tubicola, 576

Tubipora, 530

Tubularia dumortierii, 537

Tunicata, 549

Turbo marmoratus, 557

Turn-table, Shadbolt’s, 295

Typhoid bacillus, 370

Ulvaceæ, the, 411

Ulva lactuca, 411

---- thermalis, 411

Urinary salts, 236

Vallisneria, 418

Varley’s live-box, 274

Varnishes, 339

Vascular system of plants, 464

Vaucheria, 410

Vegetable tissues, staining and mounting, 310

Veins, 662

Velutina lævigata, 557

Vertebrata, 633

Vine parasites, 380

Violet sea-snail, 550

Visual angle, 72

---- judgment, 37

Volvocineæ, 404

Vorticellidæ, 499

Walmsley’s turn-table, 340

Warm chamber, Pfeiffer’s, 323

---- stage, 280

---- ---- Bartley’s, 281

---- ---- Schäfer’s, 282

---- ---- Stricker’s, 282

Wasp, sting of, 596

---- tongue of, 595

Water thyme, 419

Watson’s achromatic condenser, 177

---- bacteriological Van Heurck’s microscope, 108

---- Edinburgh student’s microscope, 102

---- histological microscope, 107

---- mechanical draw-tube, 104

---- microscope lamp, 203

---- microscopes, 102

---- parachromatic condenser, 182

---- petrological microscope, 111

---- portable microscope, 110

---- semi-mechanical stage, 107

Webster-Collins condenser, 186

Weights and measures, metric system of, 687

Wenham’s binocular microscope, 65

---- double eye-piece, 189

---- immersion condenser, 189

---- parabolic condenser, 186

---- ---- reflector, 187

---- radial microscope, 90

Wheat rust, 374

---- starch, 470

Wheel animalcules, 502

Whirligig-beetle, eyes of, 608

---- ---- leg of, 608

Wings of butterfly, 610

---- of insects, 609

---- of moth, 610

Winogradsky’s investigations of bacteria, 398

Wollaston’s simple microscope, 74

Wood, formation of, 462

Wool, 474

Worms, 562

Wort-gelatine, 330

Xylem of plants, 462

Yeast cells, 384

---- German, 388

---- Hansen’s investigations of, 387

Zeiss’s compensating eye-piece, 147

---- cover-glass gauge, 165

---- microscope, 130

Zentmayer’s Holman syphon slide, 278

Zoophytes, 515

BRADBURY, AGNEW, & CO. LD., PRINTERS, LONDON AND TONBRIDGE.

Transcriber’s Note:

Page xxiii, “l. Corystes cossivelaunus” changed to read “l. Corystes cassivelaunus”.

Page xxv ERRATA incorporated into project.

Page xix, “Acmeœa virginea, part of palate--118.” changed to read “Acmæa virginea, part of palate--118.”

Page 21, “in Fig. 13, if S, S′ are a pair of conjugate foci,” changed to read “in Fig. 12, if S, S′ are a pair of conjugate foci,”. S and S′ are in Fig. 12.

Page 89 “Bacteriological and Histol gical” changed to read “Bacteriological and Histological”.

Page 598, “Apis nillifica” changed to read “Apis mellifica”, also entry in index.

Page 663, “the papillæ of the tongue is distended and seen erect” changed to read “the papillæ of the tongue are distended and seen erect”.

Obvious printer errors corrected silently.

Inconsistent spelling and hyphenation are as in the original.

FOOTNOTES:

[1] My earliest acquaintance with the Microscope occurred in the thirties, when I fortunately became possessed of a Culpeper-Scarlet instrument, figured in the title-page.

[2] At the time this was written, scarcely a book of the kind had been published at a price within the reach of the student.

[3] For fuller information, see the Cantor Lectures on the Microscope, by the late John Mayall, F.R.M.S., “Society of Arts Journal,” 1885.

[4] “A Practical Treatise on the Use of the Microscope.” London, 1855.

[5] For further information, I must refer my readers to Parkinson’s “Treatise on Optics;” Herschel’s “Familiar Lectures on Light;” “Cyclopædia Britannica;” Everett’s translation of Deschanel’s “Physics;” and Nägeli and Schwendener’s “Theory and Practice of the Microscope,” translated by Frank Crisp, LL.D.

[6] The cornea of the eye is not so entirely the simple transparent structure as it at first sight may appear to be. It is composed of several layers, the most important of which is the nerve layer, consisting of innumerable ganglionic stellate plexus of cells held together by a network, as seen in Fig. 21, a small section stained by chloride of gold, and magnified 300 diameters. Beneath the nucleated nerve cells is a second layer of stellate cells, varying a little in their form. These nerve and stellate cells serve the purpose of maintaining the cornea in health, and must play a significant part in the dioptric system.

[7] The standard condition of perfect vision is termed _emmetropia_.

[8] _Landolt_; “The Accommodation and Refraction of the Eye,” 1886.

[9] µ = ·001 of a millimetre. This measurement is now universally employed in microscopy.

[10] Diffraction effects may be observed without a microscope, indeed, the more striking are seen in connection with telescopic vision. A beautiful series of phenomena in illustration of the diffraction of light may be produced as follows: Draw on a large sheet of paper a series of geometrical figures, arranged at equal distances in a circle. A collodion photographic picture of these being taken, a series of small transparent apertures in the elsewhere opaque film will result. This film is then mounted, so that it may be in turn brought before the centre of a small hand telescope, previously adjusted to view an image of the sun. In this way we have an apparatus of the most compact form, and by means of which a series of fifty or more phenomena may be brought into view in a few minutes. These pictures being very small (occupying on an average area one-tenth of an inch in diameter), inaccuracies of surface and substance of the glass may be neglected. A film of Canada balsam with which the glass is cemented over the picture produces no disturbance. There is a manifest advantage in the figures being small, as the size of the image is in inverse proportion to the size of the aperture.

[11] Carpenter, “The Microscope,” p. 65, 1891.

[12] “Phil. Mag.,” viii., p. 167 (1896).

[13] Professor Stokes wrote me in the following flattering terms:--“What you have submitted to me on the subject of apertures is so sound, clear, and succinct, that I have nothing to add to it. The method adapted as you have explained respecting the immersion system, I consider to be perfectly satisfactory.” Subsequently, and at my request, Sir George Stokes contributed a valuable paper on the subject to the “Transactions of the Royal Microscopical Society,” 1876, on “The Theoretical Limit of Aperture.”

[14] “On the Estimation of Aperture in the Microscope,” “Journal of the Royal Microscopical Society,” series ii. vol. i.; “Notes on Aperture, Microscopic Vision, and the Value of Wide-angled Immersion Objectives,” 1881.

[15] _Numerical aperture_ is generally used in the sense in which it was introduced in 1873 by Professor Abbe, on the basis of his theoretical investigations. Numerical aperture represents the ratio between the radius of the effective aperture (_p_) of the system on the side where the image is formed--more accurately the radius of the emerging pencils measured in the upper focal plane of the objective--and the equivalent focal length (_f_) of the latter, _i.e._,

Numerical aperture = _p_/_f_.

This ratio is equal to the product of the sine of half the angle of aperture _u_ of the incident pencils and the refractive index _n_ of the medium, situated in front of the objective. With dry lenses _n_ has therefore the value 1; with immersion lenses it is equal to the refractive index of the particular immersion fluid:

Numerical aperture = _n_ Sin _u_.

The numerical aperture of a lens determines all its essential qualities; the brightness of the image increases with a given magnification and, other things being equal, as the square of the aperture; the resolving and defining powers are directly related to it, the focal depth of differentiation of depths varies inversely as the aperture, and so forth. (Abbe, “The Estimation of Aperture,” “Journal of the Royal Microscopical Society,” 1881, p. 389.)

[16] “Journal of the Royal Microscopical Society.”

[17] “Journal Roy. Micros. Soc.,” p. 19, 1878, and p. 20, 1880.

[18] “The Magnifying Power of Short Spaces” has been ably elucidated by John Gorham, Esq., M.R.C.S. “Journal of Microscopical Society,” October, 1854.

[19] The late Mr. Coddington, of Cambridge, who had a high opinion of the value of this lens, had one of these grooved spheres executed by Mr. Carey, who gave it the name of the Coddington Lens, supposing that it was invented by the person who employed him, whereas Mr. Coddington never laid claim to it, and the circumstance of his having one made was not known until nine years after it was described by Sir David Brewster in the “Edinburgh Journal.”

[20] “Journal of the Royal Microscopical Society, 1890,” p. 420.

[21] “Journal of the Royal Microscopical Society, 1880,” p. 1050.

[22] Apo-chromatic, from the Greek, signifying freedom from colour.

[23] Prof. Abbe “On Stephenson’s System of Homogeneous Immersion for Microscope Objectives,” “Journal of the Royal Microscopical Society,” II. (1879), p. 256, and on “The Essence of Homogeneous Immersion,” Ibid., I. (1881), p. 131.

[24] Reichert, in his catalogue, does not clearly indicate what the initial powers of his eye-pieces are.

[25] Messrs. Ross have two series of eye-pieces, both Huyghenian. One series is for use with the English 10-inch tube-body, and is distinguished by Roman letters, and the other by numerals, and made as is usual on the Continent, and for use with the shorter tube-body 6-1/2-inch. The initial powers given in the table are for the 10-inch tube, and for the shorter must be read as follows:--

1 2 3 4 } with 6-1/2-inch tube. 4 6 8 12 }

[26] This centring-glass consists of a tubular cap with a minute aperture, containing two plano-convex lenses, so adjusted that the image of the aperture in the object-glass and the images of the aperture of the lenses and the diaphragms contained in the tube which holds the illuminating combination, may be all in focus at the same time, so that by the same adjustment they may be brought sufficiently near to recognise their centricity.

[27] Summary of the value of parabolic illumination and immersion illuminators, by the late Mr. J. Mayall, will be found on p. 27, “Journal of the Royal Microscopical Society” (1879).

[28] Messrs. Baker and Swift have constructed lamps with removal and fixed achromatic bull’s-eye lenses in gymbal, and changeable tinted glass screens. Either of these will add to the usefulness of the lamp in bacteriological research work. Baker’s is constructed on the Herschel doublet formula, and should therefore be free from aberration. It is mounted on a heavy brass tripod foot, has vertical and horizontal movements by rack and pinion, brass reservoir, with screw opening for filling, metal chimney to take 3 × 1-1/2-inch glass slip, removable frame for carrying tinted glass screens, &c.

[29] “Journal of the Royal Microscopical Society,” p. 365, 1896.

[30] Dr. G. A. Piersoll, “American Annual of Photography,” 1890.

[31] “Journal of the Royal Microscopical Society,” 1892, p. 684.

[32] “Journal of the Royal Microscopical Society,” p. 578, 1897.

[33] Herapath’s test-fluid is a mixture of three drachms of pure acetic acid, one drachm of alcohol, and three drops of sulphuric acid.

[34] “Journal of the Royal Microscopic Society,” 1867.

[35] Born in 1787, at Straubing, a small town in Bavaria.

[36] Dr. Thudicum’s “Tenth Report of the Medical Officer of the Privy Council, 1867.” Mr. Sorby “On Some Improvements in the Spectrum Method of Detecting Blood.” “Journal of the Royal Microscopical Society,” 1871.

[37] “On the Reduction and Oxidation of the Colouring-matter of the Blood” (“Proc. of the Royal Soc.” vol. xiii. p. 355). The oxidising solution is made as follows:--To a solution of proto-sulphate of iron, enough tartaric acid is added to prevent precipitation by alkalies. A small quantity of this solution, made slightly alkaline by ammonia or carbonate of soda, is to be added to the weak solution of blood in water.

[38] “Journal of the Royal Microscopical Society,” 1869.

[39] Professor Sylvanus Thompson, “On the Measurement of Lenses,” “Journal of the Royal Microscopical Society,” 1892, p. 109.

[40] “Journal of the Royal Microscopical Society,” 2nd Series, Vol. iv., p. 542.

[41] Mr. J. F. Smith, “On the Structure of the Valve of Pleurosigma Pellucida,” “Quekett Club Trans.”

[42] “Quarterly Journal of Microscopical Science,” New Series, Vol. viii., 1878.

[43] It is quite possible also for the student to make his own microscope stand. Mr. Field in the “English Mechanic,” pp. 171 et seq., 1897, furnishes numerous working drawings for the construction of a high-class stand, together with patterns for the metal work.

[44] “Modern Microscopy,” by Martin J. Cole.

[45] With regard to the use of absolute alcohol, this re-agent requires to be used with caution; all minute details are lost, and it causes irregular shrinking of the finer tissues, while fibrous tissue is brought into undue prominence at the expense of the cellular elements. Consequently in certain biological laboratories the method of hardening in alcohol has been abandoned in favour of other re-agents.

[46] “Journal of Anatomy and Physiology,” XX. 1881, p. 349.

[47] “Journal of the Quekett Club,” July, 1893, and March, 1895.

[48] Mr. John Hood, 50, Dallfield Walk, Dundee, offers a weekly supply of infusorial life for a small annual subscription, or a single tube by post at the trifling cost of one shilling.

[49] Professor Marshall Ward, F.R.S., “Address to the Botanical Section of the British Association, 1897.”

[50] “British Medical Journal,” March 26, 1859; “Medical Times and Gazette” and “Popular Science Review,” 1862.

[51] “Parasitic Diseases,” “Journ. of the Royal Micros. Soc. of Lond.,” 1859-60.

[52] There are several other kinds of bacteria infesting milk, some of which are motile, others non-motile, producing acidity and colouring matter, as _B. prodigiosus_, red-milk; _B. synxanthus_, yellow milk; _B. lactis aerogens_, which are pathogenic; _B. lactis albus_, which coagulate milk; and another form, which is productive of slimy or ropy-milk.

[53] “Parasitic Diseases of the Skin,” 1859-73, p. 30. Bailliere, Tindal, and Cox.

[54] “Organic Germ Theory of Disease,” “Medical Times and Gazette,” p. 685, 1870.

[55] F. Cohn on the “Natural History of _Protococcus pluvialis_.”

[56] Pritchard’s “Infusoria,” p. 24, Plate I., 4th edition.

[57] In order to detect the presence of starch-grains in plants, the tissue must be kept in alcohol exposed to light, until the whole of the chlorophyll is dissolved out; it must then be treated for several hours in a strong solution of potash. After neutralisation with acetic acid, the tissue may be treated with iodine, which colours it blue, or with coralline solution, which colours it pink.

[58] Verhandl. d. Natur. Hist. Jahr. xx. p. 1. “Micros. Jour. Science,” vol. iii., p. 120.

[59] For instance, where the yellow Palmella is found the Chlorococcus will assume a yellow tinge in its soridial stage. Viewed by transmitted light the sori are seen as opaque balls, with an irregular outline.

[60] “Contributions to the Knowledge of the Development of the Gonidia of Lichens.” By J. Braxton Hicks, M.D., “Quarterly Journal of Microscopical Science,” vol. viii., 860, p. 239.

[61] Berkeley’s “Introduction to Cryptogamic Botany,” 1857.

[62] For more detailed information on the structure and classification of unicellular plants, and cryptogams, the reader is referred to Ralfs’ “British Desmidaceæ”; Smith’s “British Diatomaceæ”; Goebel’s “Outlines of Classification and Special Morphology”; Berkeley’s “Cryptogamic Botany”; De Bary’s “Comparative Anatomy of the Phaneragams and Ferns”; Professor Marshall Ward’s “Sach’s Physiology of Plants,” and numerous memoirs on Fungi; and Bower and Sidney Vine’s “Course of Practical Instruction in Botany,” a most instructive book on the histology of plants.

[63] “A Manual of the Infusoria,” by W. Saville Kent, F.L.S., &c., 1880.

[64] “Journal of the Linn. Society,” vol. viii., p. 202; vol. ix., p. 147, 1865 and 1866.

[65] Among the more important works on Foraminifera for consultation will be found D’Orbigny’s “Foraminiferes Fossiles du Bassin Tertiaire de Vienne” (Autriche); Schultze, “Ueber den Organismus der Polythalamien,” 1854; Carpenter and Williamson’s “Researches on the Foraminifera,” “Phil. Trans. 1856;” Parker and Rupert-Jones in the “Annals of Natural History.” Specimens of Foraminifera may be obtained by shaking dried sponges; but if required alive they must be dredged for, or picked off the fronds of living seaweeds, over the surface of which they are, by the aid of a lens, seen to move.

[66] W. Saville Kent, F.L.S., Op. Cit., p. 335.

[67] Difficulties formerly associated with the microscopic examination of flagellate forms of infusorial life have been overcome by improvements in the objectives, by the knowledge gained of the monad groups, and by the exhaustive researches of Drs. Drysdale and Dallinger, whose joint investigations were published in the Journal of the Royal Microscopical Society, 1873-75. By employing the highest and most perfectly constructed powers of the microscope, and devoting an enormous amount of time and attention to unravelling mysteries so long associated with the production of the lowly organised flagellate organisms, monads, and patiently watching hour by hour, the life-history of numerous species of these minute infusorial animalcules were obtained. Not only was it discovered that these organisms increased indefinitely by fission, but that under certain conditions two or more individuals were united into encystments, and whose contents broke up into a greater or less number of spore-like bodies, were speedily developed into the parent type. In the examination of these minute bodies, it has been found that talc-films, that is, talc split into extremely fine laminæ, offer the best kind of cover, in fact, supersede ordinary glass covers, and possess an advantage, that of bending readily, thus permitting the objective to be brought close down upon the object.

[68] R. Kirkpatrick, Warne, Op. Cit., pp. 532-3.

[69] Saville Kent, _op. cit._, p. 191.

[70] Fritz Müller first demonstrated a nervous system in the Polyzoa:--“The nervous system of each branch consisting of--1st, a considerable sized ganglion situated at its origin; 2nd, of a nervous trunk running the entire length of the branch, at the upper part of which it subdivides into branches, going to the ganglia of the internodes arising at this part; and 3rd, of a rich nervous plexus resting on the trunk, and connecting the ganglia just mentioned, as well as the basal ganglia of the individual polypides.” For further account, see paper in the “Micros. Journ.,” vol. i., New Series, p. 330.

[71] I have ventured to devote some considerable space to the development of the pond-snail, and for an obvious reason, that of making it perfectly clear to my readers that my microscopical investigations of Limnœa, made in 1853, were published in the “Journal of the Microscopical Society,” June, 1854, and republished in extenso in the several editions of this book, dating from the last mentioned period. Nevertheless, the fringe of cilia was, it appears, rediscovered in 1874, just twenty years after my paper was published. It is almost unnecessary to add that Carpenter gravely errs in his statement “that the existence of the fringe of cilia in the embryo snail had been overlooked until 1874.”

[72] Mr. George Rainey many years ago made us acquainted with the fact that certain of the appearances presented by the shell or other hard structures of animals, and which had hitherto been referred to as cell-development, are really governed by the physical laws which govern the aggregation of certain crystalline salts when exposed to the action of vegetable and animal substances in a state of solution. Mr. Rainey furnished a process for obtaining artificially a crystalline substance which shall so closely resemble shell structure that it can barely be distinguished from it. The chemical substances to be used in the preparation of the artificial shell, or calculi, are a soluble compound of lime and carbonate of potash or soda, dissolved in separate portions of water, and mixed with some viscid vegetable or animal substance, as gum or albumen, and mixing the several solutions together. The mechanical conditions required are that such a quantity of each of the viscid materials in each solution shall be of about the same density as that of the nascent carbonate of lime, and at perfect rest. This state of rest will require from two to three weeks or longer. Mr. Rainey shows the analogy or identity of his artificially formed crystals with those found in natural products both in animals and vegetables, chiefly confining himself to the structure and formation of shells and bone, pigmental and other cells, and the structure and development of the crystalline lenses, which he contends are all formed upon precisely the same physical principles as the artificial crystals.

[73] E. Ray Lankester, “On the Gregarinæ found in the common Earthworm.”--“Micros. Trans.” vol. iii. p. 83.

[74] For the fullest information of marine, land, and fresh-water species, consult Dr. Bastian’s “Monograph on the Anguillulidæ”; “Lin. Soc. Trans.” vol. xxv. p. 75; the “Anguillula Aceti,” by the author, in the “Popular Science Review,” January, 1863.

[75] “Cercaria parasitic on Limnœa,” “Jour. Royal Micros. Soc.” 1870.

[76] See my paper “The Natural History of a Nematode Worm,” “Journ. of Microscopy and Natural History,” October, 1888.

[77] “The Parasites of Man and the Diseases which proceed from them,” by Professor Rudolf Leuckart, 1886.

[78] R. J. Pocock, “On Worms” (Warne, Op. cit.), p. 465.

[79] An interesting account of the formation of the tubes of Serpula is given by Mr. Watson, “Jour. Micros. Soc.,” vol. 1890, p. 685.

[80] Dr. Baird, “Natural History of British Entomostraca,” printed for the Ray Society, 1850.

[81] See Mr. B. T. Lowne’s exhaustive treatise on “The Anatomy and Physiology of the Blow-fly,” a volume of 750 pages and 52 plates, 1891.

[82] Tuffen West, “Trans. Linn. Soc.,” vol. xxiii., p. 393.

[83] The term micropyle (a little gate) has heretofore only been used in its relation with the vegetable kingdom: it is used to denote the opening or foramen towards which the radicle is always pointed.

[84] Dr. Halifax adopts the method of killing the insect with chloroform; he then immerses it in a bath of hot wax, in which it is allowed to remain until the wax becomes cold and hard; with a sharp knife sections are easily made in the required direction without in the least disturbing any of the more fragile parts, or internal organs of the specimen.

[85] “Phil. Trans.,” 1859, p. 341.

[86] See my paper on “The Eggs of Insects,” in “The Intellectual Observer,” Oct. 1867, in which other varieties of eggs are given.

[87] W. U. Whitney, “Transactions of the Microscopical Society” for 1861 and 1867.

[88] Mr. F. G. Cuttell, 52, New Compton Street, Soho, cuts and prepares excellent sections.

[89] Published with his paper in detail, “Aperture as a Factor in Microscopic Vision,” “Journal of Royal Micros. Soc.,” June, 1808, pp. 334 _et seq._

[90] “Squire’s Methods and Formulæ;” “Modern Microscopy,” Cross and M. F. Cole; “The Microscopists’ Vade Mecum,” A. B. Lee; “Bacteriology.” Professor Dr. E. Crookshank, Messrs. Baird and Tattock, Cross Street, Hatton Garden, supply all Scientific Apparatus for Bacteriological Work.

[91] The imperial gallon contains 277.27384 cubic inches, and the imperial pint 20 fluid ounces, whereas the wine gallon has 231 cubic inches and the pint 16 fluid ounces. In wine measure 1 litre = 33.815 fluid ounces.

Transcriber’s Note:

Page xxiii, “l. Corystes cossivelaunus” changed to read “l. Corystes cassivelaunus”.

Page xxv ERRATA incorporated into project.

Page xix, “Acmeœa virginea, part of palate—118.” changed to read “Acmæa virginea, part of palate—118.”

Page 21, “in Fig. 13, if S, S′ are a pair of conjugate foci,” changed to read “in Fig. 12, if S, S′ are a pair of conjugate foci,”. S and S′ are in Fig. 12.

Page 89 “Bacteriological and Histol gical” changed to read “Bacteriological and Histological”.

Page 598, “Apis nillifica” changed to read “Apis mellifica”, also entry in index.

Page 663, “the papillæ of the tongue is distended and seen erect” changed to read “the papillæ of the tongue are distended and seen erect”.

Obvious printer errors corrected silently.

Inconsistent spelling and hyphenation are as in the original.