NERVOUS SYSTEM — CYTOLOGTCAL METHODS. 395 



33 per cent., alcoholic solution of ethylaminr. Resultfs tlie 

 same as with ammoniacal alcohol. 



Formula 4a. — Pieces of tissue of not more than 4 mm. in 

 thickness are fixed for six to twelve hours in formal of 15 

 per cent. Wash for six or more hours in running water.* 

 Put for 24 hours into 50 c.c. of alcohol with five drops of 

 ammonia. Wipe with blotting paper, silver for 5 days (or 

 four if the stove is at 38° to 40° C). The rest as usual. 

 Sharp impregnation of the finer fibres of nerve centres, and 

 of the terminal buds of pericellular nests. Adult tissues 

 give better results than young ones. Energetic stain of the 

 arborisations of the mossy fibres of the cerebellum. 



Formula 4a A.-— Fix in " a mixture of formol and alcohol." 

 Wash out thoroughly with running water, and silver and 

 reduce as usual. Fixation more rapid and better, results 

 similar to those of 3a. 



Formula 5a. — Small pieces put first for 6 to 8 hours 

 into a mixture of equal parts of distilled water and j>yndin, 

 then for 18 to 24 hours mio fure fyridin . Wash for several 

 hours in running water, and put for a day into alcohol of 90 

 per cent. Wipe, and put for 4 to 5 days into the silver at 

 35 to 38° C, and reduce as usual. Not very good for adult 

 organs, but superior to all others for the earliest phases of 

 neurogenesis, and good for regenerative processes. 



Formula 6a. — Put for 24 hours into 50 c.c. of water with 

 5 grms. of hydrate of chloral, rinse and put into 50 c.c. of 

 alcohol of 96 per cent, with five drops of ammonia (time not 

 stated). Wipe with blotting paper and put for 4 to 5 days 

 at 35° to 38° C. into nitrate of silver of I'o per cent, and 

 reduce as usual. Results very constant, without shrinkage. 

 Stains perfectly the fine plexuses of cerebrum, bulb and 

 cord, the Purkinje baskets and mossy fibres ; also motor 

 plates. Nuclei sufficiently stained to enable cells to be easily 

 recognised. Good for regenerating nerves. 



Formula 6a A. — Fix for 24 hours in chloral of 10 per cent., 

 wash for 6, and put direct into the silver. Stove four days. 

 Results similar to those of la. Medullated fibres well 

 stained. 



* If formol (or pyridin or the like) be not thoroughly removed by 

 washing, the stain will be weakened, and of a light reddish tone. (But 

 I am not clear that this vigorous washing out is altogether advisable.'* 



