314 JoiiKNAI. OF COMPAKATIXE NeUROLOGY. 



of copper in the chromium compound within the sheaths; 

 (3) staining with hematoxylin; (4) differentiation by means 

 of borax-ferricyanid of potassium. The precipitate wliich 

 tends to appear during the staining is prevented by the addi- 

 tion of the carbonate of lithium. 



The modified method, as here published for the first time, 

 is as follows: Fragments suitable for microscopic sections are 

 thoroughly hardened in bichromate of potassium, and, after 

 treatment with alcohol, are imbedded in celloidin. After 

 coagulation in 80 per cent, alcohol they were, according to 

 the old method, brought into a solution of neutral cupric 

 acetate in an equal volume of water and kept in the brood- 

 oven twenty- four hours. The modification consists in the 

 substitution of equal volumes of neutral cupric acetate and 

 tartrate of soda (C*H^0''KNa-|--4H'-0). Large fragments 

 may remain for forty-eight hours without injury, provided 

 the temperature is not permitted to rise too high. The frag- 

 ment then is passed into an aqueous solution of cupric ace- 

 tate and remains twenty-four hours longer in the warm 

 chamber. After rinsing, the specimens go into 80 per cent, 

 alcohol, where they become available for sectioning any time 

 after an hour or so. 



For staining, two stock solutions are required: (A) 7 c.cm. 

 saturated aqueous solution of carbonate of lithium -|- 93 c.cm. 

 distilled water; (I>) i gm. hicmotoxylin -\- 10 c.cm. alcohol. 

 These are to be combined just before using in the proportion 

 of 9 volumes of yl to i volume o^ B. Sections stain in three 

 or four hours, though the staining is not injured by leaving 

 them twenty-four hours in the fluid. This process is, unfor- 

 tunately, only available for free sections, which then require 

 no development, but, after rinsing, are brought into 90 per 

 cent, alcohol and are cleared in a mixture of 2 volumes of 

 analin oil -|- i volume of xylol, followed by pure xylol and 

 balsam. 



