Strong, Review of the Golgi Method. 105 



upon another series. A warm chamber, of which I shall speak 

 later, cannot bring about the accuracy sought for, 



" The surest means of remedying these inconveniences is 

 the persevering repetition of the process, i. e. one must have a 

 good number of pieces available, bring several from time to 

 time into the silver solution and then ascertain whether they are 

 in the desired condition. If a good reaction has taken place, 

 one continues the trials at regular intervals in order to obtain 

 all the stages of the reaction, which constitute an advantage of 

 this method. It is self-evident that the different trials must fol- 

 low 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 de- 

 sired hardening is first reached after a month, the trials can be 

 made at intervals of 8 to 10 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 into 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 

 bichromate into the solution of silver, this is no ground for con- 

 cluding that the method is subject to excessive uncertainty. All 

 difficulties are overcome and one can be absolutely sure of al- 

 ways 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 ^ %% silver solution; yet I will remark 

 that it is not necessary to adhere closely to this formula to ob- 

 tain the reaction. A slightly stronger or weaker solution does 

 not affect the result. I will also add that a slightly weaker so 



