CENTRAL ORGANS OF NERVOUS SYSTEM. 221 



terior. The latter here forms the wedge-shaped or Goll's 

 column. The inner nerve fibres, that is, those which are 

 adjacent to the gray cornua, are also usually finer than their 

 external associates. 



These longitudinally arranged fibrous masses are permeated 

 by the bundles of the transversely and obliquely departing 

 and entering roots of the spinal cord. 



The anterior or motory roots of the latter reach the anterior 

 cornu (Fig. 187, i), and radiate into the latter in every direc- 

 tion in a brush-like form. 



Let us now examine this gray substance of the anterior 

 cornu. 



Here (d) lie groups of large multipolar ganglion cells, after 

 the manner of our Fig. 176. The so-called axis-cylinder pro- 

 cess (a) is the commencement of the motory nerve fibre, its 

 axis cylinder. This is settled, according to my experience, 

 although it has recently been doubted (Golgi). It is certainly 

 not easy to observe, but it is and remains the best portion of 

 our present knowledge concerning the origin of nervous ele- 

 ments in this so infinitely complicated organ. 



If we turn further backwards towards the posterior cornu, 

 we meet with, for the most part, smaller, not rarely spindle- 

 shaped cells (/), with the same duplicity of systems of pro- 

 cesses. At the base of the posterior cornu, further inwards, 

 there is also a group of smaller rounded ganglion cells. 

 These are the Clarke's columns. 



The cellular elements of the posterior cornu have generally 

 been considered as sensory, and brought into relation with 

 the origin of the fibres of the posterior roots ; still this cannot 

 be demonstrated. 



We now encounter the question : What becomes of the 

 second system of processes (Fig. 176), the so-called proto- 

 plasma processes ? 



Their lateral finest filaments (b), like the terminal radiations 

 of the branch itself, were considered by Deiters, as we already 

 know, to be primitive nerve fibrillar. From them — and they 

 might arise from different cells — an axis cylinder was said to 



