STAINS, ETC. 



the same properties and is used in the same way 

 as clove-oil. Naphtha clears paraffin or celloidin 

 sections, but is too volatile for a general clearing 

 agent. Oil of Origanum. Ninety-five per cent, 

 alcohol preparations are quickly cleared, also celloidin 

 sections. For the latter, Oleum origani cretici should 

 be used. Anilin colors are somewhat extracted by 

 this agent. Sandal-wood Oil. Ninety-five per 

 cent, alcohol preparations are cleared rapidly, celloidin 

 sections more slowly, by this agent. Anilin colors are 

 not affected by it. Toluol clears paraffin and cel- 

 loidin sections, and is sometimes used as a penetration- 

 fluid before the paraffin bath. Turpentine. This 

 agent has a low index of refraction, and, used for al- 

 cohol objects, causes contraction and alters the struc- 

 ture of cells. It is much used for paraffin sections, 

 as it possesses the property of dissolving the par- 

 affin and clearing the section at the same time. Xylol 

 is used for paraffin and celloidin sections. It causes 

 shrinkage if the sections are not thoroughly dehy- 

 ted. 



CORROSION-METHODS. 

 Boiling or prolonged soaking in strong solution of Caustic 

 Soda will remove the soft parts from skeletal struc- 

 tures. Caustic potash may be used in the same way. 

 Eau de Javelle [Potassium Hypochlorite). Rub up 

 20 gm. of chlorinated lime in loo c.c. of distilled 

 water ; dissolve 20 gm. of potassium carbonate in IOO 

 c.c. of distilled water; mix, and after one hour filter. 

 This solution is particularly recommended for prepar- 

 ing the skeleton of siliceous sponges and that of 

 similar structures. In the study of the iris, choroid, 

 and other pigmented organs, Altmann recommends 

 Javelle water. Fat, especially when previously treated 

 with osmic acid, resists the action of this fluid. The 

 tissue impregnated with fat is hardened in osmic acid, 

 and treated with Javelle water, which destroys every- 

 thing hut the fat, which remains as an osmium-stained 

 mold of the tissue-spaces. Eau de Labarraque. [So- 

 dium Hypochlorite) . Twenty grams of chlorinated lime 

 are rubbed up in 100 c.c. of distilled water and mixed 

 with 40 gm. of crystallized sodium carbonate dissolved 

 in the same quantity of water. Let the mixture stand 

 for an hour, and filter. This is used in the same way 

 as Javelle water. With the aid of heat, chitin is dis- 

 solved in either of the solutions in a short time (Loos). 

 Chitinous structures, macerated for 24 hours or more in 

 these solutions diluted with 4 to 6 volumes of water, 

 become soft and transparent, and permeable to stain- 

 ing fluids, aqueous or alcoholic. This method is es- 

 pecially applicable to Nematoda and their ova. Hyrtl's 

 Corrosion-method. Commercial mastic varnish is 

 gradually evaporated over a spirit-lamp, or by other 

 means, until it is of such a hardness that it cannot be 

 indented with the finger, and with difficulty with the 

 finger nail. The varnish should never be heated to 

 boiling. By means of a glass rod, allow a drop of 

 hot varnish to fall in cold water ; if this cannot be 

 flattened out between the fingers when cold, and only 

 with difficulty after warming in the palm of the hand 

 or on the tongue, it is sufficiently evaporated. To six 

 parts of hardened varnish add one part of white bees- 

 wax. To color the injection-mass, five colors are re- 

 commended : For red mass, cinnabar ; for blue, cobalt 

 or ultramarine ; for yellow, light or dark chrome- yel- 

 low ; lor green, emerald green; for white, carbonate 

 of lead. The latter holds more poorly than the others, 

 becoming somewhat brownish after heating. To 24 

 ounces of the mass, add from 16 to 20 drams of the 

 color : a little more than this for the blue and green. 

 The colors should be rubbed up evenly in a mortar, 



1369 CYTOLOGIC METHODS 



with enough of the fluid varnish to give a syrupy con- 

 sistency, and this mixture poured slowly into the 

 heated mass, while constantly stirring with a small 

 wooden spatula. The mass is warmed, preparatory 

 to injection, over an ordinary spirit-lamp, to a tempera- 

 ture just short of boiling, and should fie constantly 

 stirred. The method of injecting the varnish mass 

 differs in no way from that of ordinary injections. I'or 

 corroding away the fleshy parenchyma, concentrated 

 hydrochloric acid is used. The organ is placed in a 

 glass jar, of a depth at least two inches greater than 

 the diameter of trie organ. It is first rinsed with cold 

 water, and then the cold acid poured over it in suffi- 

 cient quantity to float it. The greater the amount of 

 acid, the quicker the corrosion. From two to ten 

 days will be required for corrosion, according to the 

 size and density of the organ. A fine spray or jet of 

 water is then played upon the organ, and the corroded 

 flesh carefully washed away. The preparation is then 

 laid for two or three hours in clean water and then 

 dried and mounted. Noll's Method : Place a piece 

 of sponge on a slide, and treat it with a few drops of 

 eau de Javelle ; the soft parts will dissolve in 20 to 30 

 minutes ; remove any precipitates by cautious treatment 

 with acetic acid, wash several times in alcohol, treat 

 with oil of cloves, and mount in balsam. In Wood's 

 Metal Corrosion Method, the organ to be injected 

 is placed in water of a temperature to keep the metal 

 used in a fluid condition, and the liquid metal is injected 

 by ordinary methods. The injected organ is then placed 

 in cold, running water until the flesh has macerated 

 away, when the cast is cleaned with a brush. 



COVER-GLASS PREPARATIONS. 



Such preparations are usually made in examining blood, 

 sputum, or other fluid or semi-fluid substance. In the 

 case of sputum a tiny mass is placed on a cover-glass, 

 another is pressed gently down upon this, and the two 

 glasses are separated by sliding one over the other, the 

 object being to secure a thin, even film on each glass. 

 The film may also be spread with the edge of a cover- 

 glass or with a platinum spatula. The preparations 

 are then left to dry in air, or they may be dried by 

 exposing them to a temperature of 120 for twenty 

 minutes, or by passing them quickly thrice through 

 the flame of a spirit-lamp or Bunsen burner. When 

 dry, they are ready to stain. To obtain a cover-glass 

 preparation of blood, cleanse the finger, prick the 

 pad, wipe off the first drop of blood that exudes, touch 

 the apex of the second drop with a cover-glass, spread 

 in the manner described, and dry in air. 



CYTOLOGIC METHODS. 

 Cell -structure may be studied in living cells, in fresh, 

 unhardened cells, and in hardened tissue in sections. 

 Accessory Nuclei. Fix the tissue in Flemming's solu- 

 tion for I hour, then place it for 24 hours in Flemming's 

 fluid diluted 3 or 4 times ; wash thoroughly, harden 

 in alcohols of increasing strength. Stain for 24 hours 

 with hematoxylin according to Apathy's modification 

 of Heidenhain's method; keep in the dark. Decol- 

 orize in a I per cent, alcoholic solution of potassium 

 bichromate prepared just before using (by mixing 70 

 c.c. of strong alcohol with 30 c.c. of a stock solution 

 of potassium bichromate 10 parts, distilled water 300 

 parts). The decolorizing mixture should be put in a 

 dark-colored glass bottle, and the tissue left in for from 

 12 to 24 hours, according as a light or dark stain is 

 desired. Pass into 70 per cent, alcohol — also in a dark 

 bottle, and after one or more days dehydrate in abso- 



