Strong, Rcvictv of the Golgi Method. 1 1 1 



and that finally the so-called ganglia of the stem reach the prop- 

 er hardening still somewhat later than the parts named. 



" A last remark. When the above-described peculiarities 

 of the process are considered, it is intelligible how it often hap- 

 pens that the reaction appears only in one part of the piece. 

 For example, it is absent in the superficial layers, where there 

 is, as a matter of fact, more often than otherwise only an irregu- 

 lar precipitate, and is present in the interior or vice versa. One 

 must remember this and when, very likely, the first sections 

 made near the surface show nothing of interest one must not 

 thereupon conclude that the reaction has failed, for it often hap- 

 pens that such preparations, in which only single, isolated cells 

 are stained, are among the most instructive for details of the in- 

 dividual elements. 



" Treatment atid Preservation of Preparations. Whether 

 the black stain has turned out so that the piece is worth keep- 

 ing for further investigation can be ascertained by means of trial 

 sections examined in glycerine or in the reaction fluid itself. 

 Then one must provide for the preservation of the piece and the 

 microscopical sections. Although it is certain that a longer so- 

 journ in the silver solution does no harm whatever and that such 

 a sojourn may serve as a means of preservation, yet is expedi- 

 dient, in order to have the pieces ready for further treatment, to 

 transfer them to pure commercial alcohol. This not only serves 

 to harden the tissue farther but also to free it from the silver 

 nitrate which, as I shall mention below, is very injurious to the 

 preservation of the microscopical sections. To accomplish the 

 latter the alchol should be changed two or three times till it re- 

 mains transparent for a number of days after the piece is brought 

 into it. In this way the pieces can be kept a long time. I 

 have kept them for about nine years in this way and can obtain 

 from them, when I wish, preparations as clear as those obtained 

 from them shortly after their preparation. 



"The further treatment of the microscopical sections cor- 

 responds essentially with the usual procedure in obtaining 

 anhydrous preparations except for some peculiarities necessary to 



