A REVIEW OF THE GOLGI METHOD. 159 



either immediately or later be tried, /.t?., during a period of from 

 3 or 4 to 25 or 30 days after the immersion. If one during this 

 whole period transfers, at intervals of 2 to 3 or 4 days, some pieces 

 into the osmium-bichromate solution, he thus possesses many 

 secondary series of pieces which are brought singly (one or two at 

 a time) into the nitrate solution. These, from the third or fourth 

 to the eighth or tenth day of their sojourn in the mixture, yield 

 with certainty, when brought into the silver, preparations with all 

 the consecutive gradations and combinations described in the 

 original method, and also possessing surprising fineness. 



'■''After-treatment. Preservation of the pieces in the silver 

 solution ; pure alcohol for 2 or 3 days, till one has time to under- 

 take the examination ; repeated washing out of the sections with 

 absolute alcohol ; creosote, turpentine, damar, mounting without 

 cover glass. 



" This is the method which I at present prefer for the demon- 

 stration of the finest details in the structure of the central nervous 

 system. The particular grounds for this preference are the follow- 

 ing : (i) Certainty of obtaining the reaction in many gradations, 

 if one makes use of a certain number of pieces. (2) The con- 

 siderable length of time during which one can obtain the reaction 

 — while one can also attain it in a few days. This renders an 

 accurate investigation much easier. (3) The pieces are much 

 more conveniently treated. (4) Finally, one obtains at the same 

 time with the gentle gradation of the results also a greater fineness 

 of the same, especially regarding the behaviour of the functional 

 processes of the ganglion cells. 



"3. — Method of the consecutive actions of the bichromate of 

 potassium a?id of bichloride of mercury. This can likewise yield 

 valuable results whose value is not diminished because they, in 

 many respects, conform to those obtained by the silver nitrate. 

 Indeed, the particular purposes it can fulfil, and its peculiar 

 advantages, are in and for themselves so important that it must be 

 given a place of its own alongside the silver nitrate method. The 

 clearness with which the various elements of the nervous system 

 emerge in this reaction is not less than that brought about by the 

 silver nitrate. The elements appear, when viewed under the 

 microscope by transmitted light, completely black after the action 



