NEUROLOGICAL METHODS. 429 



5 per cent, of neutral acetate of copper, 5 per cent, of 

 acetic acid, and 2J per cent, of chrome alum, in water. 

 (Add the alum to the water, raise to boiling point, and add 

 the acetic acid and the acetate, powdered.) 



After the mordanting the tissues are washed with water, 

 dehydrated, imbedded in celloidin, and sectioned. The sec- 

 tions are treated for ten minutes with a one third per cent, 

 solution of permanganate of potash, and well washed in 

 water. They are then treated for two to four hours with a 

 solution of " Chromogen." " Chromogen " is a naphthalin 

 compound prepared by the Hoechst dye manufactory. The 

 solution of " Chromogen " to be used is prepared as follows : 

 5 per cent, of " Chromogen " and 5 per cent, of formic 

 acid are dissolved in water, and the solution carefully filtered. 

 To 90 c.c. of the filtrate are added 10 c.c. of 10 per cent, 

 solution of sodium sulphite. 



After this bath, the sections are put till next day into a 

 saturated (5 per cent.) solution of Chromogen. 



They are next carefully washed and submitted to the 

 stain. The stain is a modification of WEIQKKT'S fibrin stain. 

 Instead of saturated aqueous solution of methyl violet, you 

 take a warm-saturated solution in 70 per cent, or 80 per 

 cent, alcohol, decant it after cooling, and add to it 5 per 

 cent, of aqueous solution of oxalic acid ; and instead of 

 treating with pure anilin, you take a mixture of equal parts 

 of anilin and xylol. This is afterwards removed from the 

 sections by means of pure xylol, and they are mounted in 

 balsam. 



MALLORY (Journ. Exper. Med., 1897, p. 532) finds that 

 tissues can be mordanted for the stain by means of a chrome 

 salt. He fixes them for four days in 10 percent, solution of 

 formalin, then for four to eight in saturated solution of picric 

 acid (or for the same time in a mixture of the two), then 

 mordants for four to six days at 37 C. in 5 per cent, solu- 

 tion of bichromate of ammonia, makes sections (celloidin) and 

 stains them in WEIGERT'S fibrin stain. 



See also the modification of Weigert's stain by STORCH, Virchow's Arch., 

 clvii, 1899, p. 127 ; Zeit.f. wiss. Mik., xvi, 4, 1900, p. 475. 



776. Saurerubin for Neuroglia. KULTSCHITZKY (Anat. Anz., 

 viii, 1893, p. 357) stains paraffin sections, either for five to 



