BIEL8CH0W8KY 489 



small specimens of adult subjects. This method has been described 

 by Bielschowsky in various ways, probably because of the difficulty 

 of giving fixed rides in a case in which the greatest freedom had 

 to be left to histologists to adapt the method to the quality of 

 their material and the purpose of their investigations. In what 

 follows two forms of the method are described : one without and 

 one with pyridine treatment of pieces. 



A. Method for Pieces zvithout Pyridine Treatment. Thin slices 

 or small pieces of formol material are washed for some hours, 

 first in running tap-water and afterwards in distilled water. 

 They are then placed in a 2 per cent, solution of silver nitrate 

 for from one to eight days in the dark. The use of an incubator 

 at 35° to 37° C. is optional. After a wash in several changes of 

 distilled water (to be prolonged for some minutes vip to some 

 hours according to the length of time during which pieces have 

 been kept in the silver bath, and if in an incubator or not) they 

 are transferred into an ammoniacal solution of silver nitrate 

 prepared as in the method for sections, but diluted up to 100 c.c. 

 They are kept therein for from an hour up to six, washed once 

 more in distilled water, passed for twelve to twenty-four hours 

 into the usual 20 per cent, solution of formalin. Wash, dehydrate 

 quickly, imbed, preferably in paraffin, tone sections as described 

 above, counterstain, if necessary, mount in balsam. 



B. Method for Pieces with Pyridine Treatment. Pieces of 

 formol material, up to 1 cm. thick for adult tissue, and up to 

 5 cm. long for embryos, are put for two, three or four days into pure 

 pyridine, washed for some hours in several changes of distilled 

 water and put for three to five days into 3 per cent, silver nitrate 

 at 36° C. Wash in distilled water and transfer into the diluted 

 ammoniacal silver bath as above, but leaving pieces therein for 

 twenty-four hours. Wash for about two hours in several changes 

 of distilled water, reduce in 20 per cent, formalin. The rest as 

 above. 



1021. Method for Membranous Labyrinth of Mammals. 1. Fix 

 entire temporal bone in 20 per cent, formalin with 5 per cent, 

 nitric acid, and decalcify completely in this. Return to 20 per 

 cent, formalin. 



2. Make frozen sections, wash and place in 4 per cent, silver 

 nitrate for twenty-four hours in the dark. 



3. W^ash rapidly and put sections for a few minutes until they 

 have a brownish tone in an ammoniacal silver nitrate solution 

 made as follows : To 5 c.c. of 20 per cent, silver nitrate add 

 5 drops of 40 per cent, caustic soda ; add anunonia to dissolve 

 the precipitate, and add 20 c.c. of distilled water. 



4. Wash sections in slightly acidulated water (1 drop of acetic 

 acid to 20 c.c. of distilled water). 



5. Reduce in 20 per cent, formalin. 



