80 REVIEW OF THE GOLGI METHOD. 



of the reaction, which constitute an advantage of this method. It 

 is self-evident that the different trials must follow each other at 

 intervals differing according to the time of the year. In the warm 

 season, when the requisite hardening is reached much earlier, the 

 trials must follow each other more quickly ; in the cold season, on 

 the other hand, when the desired hardening is first reached after a 

 month, the trials can be made at intervals of eight to ten days, 

 beginning with the time when one, according to my direction, has 

 ground to assume that the tissue has begun to enter the desired 

 condition. 



" (b) Transference of the hardened pieces t?ito the solution of 

 silver nitrate. Although the various conditions of which I have 

 spoken make it impossible to state with complete accuracy for how 

 many weeks or days the pieces must be brought from the bichro- 

 mate into the solution of silver, this is no ground for concluding 

 that the method is subject to excessive uncertainty." All diffi- 

 culties are overcome, and one can be absolutely sure of always 

 obtaining excellent results by the simple procedure of steadily 

 extending the trials with every series of pieces. The difficulties 

 are thus very like those which one encounters in the employment 

 of all other impregnation and imbibition processes, not excepting 

 the simple carmine staining, in which, as is well known, one only 

 reaches quick and certain results after repeated trials when he has 

 learned to know the nature of the staining fluid and of the pieces 

 to be stained. 



" I usually employ a ^ per cent, silver solution ; yet I will 

 remark that it is not necessary to adhere closely to this formula to 

 obtain the reaction. A slightly stronger or weaker solution does 

 not affect the result. , I will also add that a slightly weaker solu- 

 tion (J per cent.) appears to be somewhat more suitable (giving 

 finer results though confined to fewer elements) so long as the 

 pieces have not yet reached the complete hardening, while a 

 slightly stronger solution (to i per cent.) appears better adapted 

 for pieces whose hardening has progressed a little too far. 



" The quantity of the silver solution to be used must vary with 

 the number and size of the pieces to be laid therein, but must be 

 relatively abundant. For two or three pieces of about i ccm., I 

 use about half a beaker (bicchiere) of the fluid. 



