114 Journal of Comparative Neurology, 



a fineness not only not exaggerated but inferior to the natural ob- 

 ject. I will here only bring forward the disadvantages of the 

 method, in order to give the means by which they are to be 

 avoided. The long time between the placing of the pieces in 

 bichromate and the appearance of the reaction (it not infre- 

 quently happens that in consequence of this the pieces are for- 

 gotten), the uncertainty about the extremely variable time re- 

 quired to reach the proper hardening, the different conditions 

 in which individual layers of the same piece are found, all these 

 are disadvantages whose removal would be desirable, 



"I have sought by expedients to change my method in 

 one way or another in order to secure greater certainty and ac- 

 curacy in the results. Among the means tried by me I pre- 

 sent the following which have yielded me a certain advantage, 



" (a) Injixtions of bichromate (solution to 2^^, ) ^ It must 

 be abundantly and constantly applied so that the whole paren- 

 chyma of the part to be investigated is fully and uniformly 

 penetrated by the hardening fluid. The fixation of the elements 

 by the reagent, where possible, before the slightest post mortem 

 change can take place is of the highest importance in securing 

 a very delicate reaction. The action of the injection consists 

 principally in giving a uniform hardening, furthermore in pre- 

 venting, very likely, a slight post mortem change in the in- 

 terior of the piece and finally in abbreviating the sojourn in 

 bichromate, 



*' If I may draw a conclusion from some especially suc- 

 cessful reactions accomplished in this way, I must declare that 

 the injection is in these various respects actually of consider- 

 able advantage. Some other experiments, not yet very ex- 

 tended, have convinced me that a favorable influence is exerted 

 in the same way by injecting, not a simple solution of bichro- 

 mate, but one with gelatine added (2^^^ bichromate, 1 00 cc. ; 

 dry gelatine, which is dissolved in the usual way, 5 to 6 grams). 

 This procedure appears to me especially fitted to give the 



' A stronger solution would probably be better, inasmuch as it undergoes 

 dilution in the tissue. — Writer. 



