REVIEW OF THE GOLCI METHOD. 85 



cells, it is limited among the ganglion cells, it is precisely among 

 isolated blackened cells that the stain of the individual functional 

 (axis-cylinder) processes is finest ; one can observe the smallest 

 details of their course and branching. I must again recall that 

 the reaction must be produced in a series of pieces which have 

 consecutively received suitable treatment in order to learn to know 

 all its phases. 



" After we have so circumstantially laid down the fundamental 

 rules of procedure, it would be superfluous to go into particulars 

 about the differences obtaining between the different provinces of 

 the central nervous system (the cortex cerebri^ the so-called ganglia 

 of the base, the cerebellum, the spinal cord). I only remark here 

 that, under similar conditions, pieces from the cortex reach in 

 bichromate the suitable state of hardening somewhat sooner than 

 those from the cerebellar laminae, that the latter reach it a little 

 later than pieces of the spinal cord, and that finally the so-called 

 ganglia of the stem reach the proper 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 happens 

 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 irregular precipi- 

 tate, and is at 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 con- 

 clude that the reaction has failed, for it often happens that such 

 preparations, in which only single, isolated cells are stained, are 

 among the most instructive for details of the individual elements. 



[to be continued.] 



We are glad to be able to state that Mr. Vine will continue 

 his very interesting series of papers on "The Predacious and 

 Parasitic Enemies of the Aphides " in an early part of the Journal. 



International Journal of Microscopy and Natural Science 

 Third Series. Vol. VII. 



