202 



THE AMERICAN MONTHLY 



[November 



hard in seven or eight days. Much 

 better results are obtained when Mtil- 

 ler's fluid alone is used, and is kept 

 while the hardening is going on at a 

 temperature of 42^-45^0. By this 

 means in five or six days a whole 

 human medulla is hard enough to 

 cut. The fluid should be changed 

 daily. 



After becoming sufficiently hard, 

 the tissue may be embedded in cel- 

 loidine, or simpl}' cut in thick slices, 

 and these gummed on cork. After 

 being gummed on cork they are left 

 for a few hours (5 to 10) in absolute 

 alcohol. If the hardening has been 

 perfect, it is possible to cut with a 

 sharp knife on the sliding microtome 

 sections of -gL of millimetre without 

 any process of embedding. After the 

 sections have been cut they are placed 

 in water which contains i or 3 percent, 

 of alcohol. This small addition of al- 

 cohol is necessary to prevent the sec- 

 tions from breaking up. From the 

 water the sections are placed in a dish 

 filled with saturated aqueous solution 

 of acid fuchsin. This is altogether 

 different from the ordinary fuchsin 

 which is used in •staining tubercle 

 bacilli, and its staining substance is 

 an acid instead of a base, as in the 

 common fuchsin. The sections re- 

 main in the staining solution for ten 

 to twenty hours at ordinary temper- 

 atures, or for two hours at a temper- 

 ature of 40°-45°C. After being 

 slightly washed in water they are 

 placed in a solution of caustic ]30tash 

 in absolute alcohol, i-iooo. This is 

 best made by keeping on hand a 

 standard one per cent, solution, and 

 diluting this ten times before using. 

 The sections I'emain in this solution 

 until a differentiation of the tissue is 

 seen, the white matter remaining an 

 intense red and the grey gradually 

 becoming paler. The whole success 

 of the staining depends on the wash- 

 ing out, and the sections must be 

 carefully watched until the proper de- 

 gree of differentiation is seen. Then 

 the sections are placed in distilled 

 water and after remaining in this a 



few minutes put through alcohol and 

 mounted in balsam. 



Xylol will be found to answer bet- 

 ter to extract the alcohol than any 

 other agent. The nerve fibi"es, both 

 in the white and grey matter, will be 

 stained a brilliant red and the nei"ve 

 cells and nuclei a bluish red. If it 

 be desired to make the staining of the 

 nerve cells more prominent, the sec- 

 tions may be afterwards stained in 

 haematoxylin. This method was dis- 

 covered by Weigert ( Central-Blatt 

 F. D. Med. JVz'ssensc/i., 1882, p. 

 751), and he has lately (^Fortschritt 

 D. Med.., Mai, 1884) published an- 

 other method which is not only more 

 simple, but gives results which are in 

 the main better. It is proper to say 

 here that Prof. Weigert has done, per- 

 haps, as much as any man living to 

 give us methods of working which 

 have been of incalculable benefit, not 

 only in pure histology, but in path- 

 ology. 



After the tissues have been har- 

 dened in Mtiller's fluid in the manner 

 just described the sections are placed 

 in water, and from this into the fol- 

 lowing solution of haematoxylin : — 



Haematoxylin 0.75 



Absolute alcohol 10.00 



Boiling distilled water 100.00 



They should i^emain in this (fil- 

 tered) solution at a temperature of 

 45° C. for one hour ; they will then 

 be an intense, dark-blue color, and 

 uniformh' stained. No differentia- 

 tion of the grey matter from the white 

 can be obsei^ved. .From the hema- 

 toxylin solution they come into the 

 following : — - 



Borax 2.0 



Potassium ferric3^anide 5-'^ 



Water 100. o 



This has the same effect in bring- 

 ing about a differentiation that the 

 potash solution had on the fuchsin 

 preparations, the white matter re- 

 maining blue and the grey becoming 

 paler. The secret of successful stain- 

 ing in both methods lies in the decol- 

 orization. A little experience will. 



