W. L. Andriezeu, On a system of fibre-cells. 533 



Technique. 

 Thin slices are cut of the cortex, 3 — 4 mm. in diameter, and 

 immersed in a large quantity of 



K. Bichromate 2 pc 95 pts. 



OSO4 1 pc 5 pts. 



for 24 hrs. in the dark. 



To 100 cc. of the mixture add 1 drop of saturated solution of 

 Clu'omic acid, and 1 drop of pure Formic acid, just before using. 

 A good penetration of the reagent is thus secured. 



After fixation and hardening for 24 hrs., transfer into a fluid 

 composed of 



K. Bichromate 2V2 PC 90 pts. 



OSO4 1 pc 10 pts. 



in wliich the specimen (Human Brain) lies for 2 days. 



Finally place it in Golgi's Osmic Bichromate mixture of 



K. Bichromate 3 pc . . . . . . . 80 pts. 



OSO4 1 pc 20 pts. 



In this last mixture the specimen lies for a period varying from 

 a few hours to 4 days. 



The total fixation — and — hardening process varies with the 

 size, density and nature of the Brain used: Human Brains gave good 

 results in 4 — 5 days, thus a little overhardening (up to 6 days) did no 

 harm, provided the further directions were strictly followed. Under- 

 hardening was quite inadequate for the Human Brain. The specimens 

 Avere rinsed in distilled water for 1 or 2 seconds, and than plunged 

 into AgNOg of ^4 pc. as for Golgi's method. The silver solution was 

 changed in a few minutes (5 — 15 min.) and then the specimen placed 

 in a bottle of AgNOg (about 120 cc), being freely suspended in the 

 fluid by a glass hooh. The whole was placed in an incubator at 

 25 — 270 Cent, to allow of the penetration of the silver Nitrate, and 

 the even staining of the specimen, the time varying fi'om 3 to 6 days. 

 Fom- to five days gave good average results. The after treatment 

 was sectioning under spirit, dehydrating in 95 pc. alcohol (if the block 

 was infiltrated with celloidin before section cutting), and then placing 

 it in a mixture of equal parts of xylol and pyridine. 



