STRUCTURE OF THE GREY SUBSTANCE OF THE SPINAL CORD. 353 



in a few instances even undergo still further subdivision. 

 Resting on this observation, Deiters considers these ultimate 

 divisions of the protoplasmic processes to be indentical with 

 the axis-cylinders of the finest nerve fibres, and to consti- 

 tute a system of nerve tracts connected with the ganglion 

 cells. Had Deiters advanced one step further, he must have 

 discovered the fine plexus of nerve fibres of the grey substance ; 

 but as he did not apply the carminate of ammonia to his pre- 

 parations, and was unacquainted with the chloride of gold 

 method, this plexus escaped his observation. My own obser- 

 vations corroborate those of Deiters on this point, but I hold in 

 addition that the finest ramifications of the protoplasmic pro- 

 cesses ultimately participate in the formation of the fine plexus 

 of nerve fibres which I regard as an essential constituent of the 

 grey substance of the spinal cord. (See fig. 223.) The branches 

 already noticed by Deiters of the finest protoplasmic processes 

 surrounded by a double contour, are simply the commencement 

 of this nerve-fibre plexus. The cells of the grey substance pro- 

 vided with nerve and protoplasmic processes are therefore doubly 

 connected with the nerve-fibre elements of the spinal cord, on 

 the one hand by means of the nerve-process which becomes the 

 axis-fibre of the tubules of the anterior roots, and secondly 

 through the finest ramifications of the protoplasmic processes 

 which constitute a part of the fine plexus of nerve-fibres of tJie 

 grey substance. 



The third of the above-mentioned questions, having reference 

 to the invariable occurrence of the nerve-process in all the gan- 

 glionic cells of the grey substance of the spinal cord, is difficult 

 to answer, because in sections this process is only exception- 

 ably visible; and in preparations that have been teazed out 

 with needles the objection may always be raised that the 

 nerve-process has been torn away at the thinner portion by 

 which it is connected with the cell. That Deiters should 

 extend his important discovery to all the ganglion cells of the 

 spinal cord was natural, especially as he had demonstrated the 

 occurrence of the nerve-process both in the larger and smaller 

 cells. Deiters consequently did not even refer to the possi- 

 bility of the occurrence of cells destitute of the nerve-process. 

 I am of opinion, however, that a different answer may be given 



VOL. II. A A* 



