HISTOLOGY OF SPINAL COED. 



179 



network through the whole gray substance. The fibres of 

 the anterior roots of the spinal nerves enter the gray mat- 

 ter and there become continuous with the unbranched pro- 

 cess of a nerve-cell; the ending of the posterior root-fibres 

 is not quite certain, but they appear to break up and join 

 the gray network directly, without the intervention of a 

 cell. In any case the fundamental fact remains that every 

 nerve-fibre joining the spinal cord is directly or indirectly 

 in continuity with the gray network and so with all the 



FIG. 75. A small bit of the section represented in Fig. 74 more magnified, a, 

 a bundle of fibres from an anterior root passing through the white substance 

 on its way to the gray. Towards the right of the figure the nerve-fibres of the 

 anterior column have been omitted so as to render more conspicuous the sup- 

 porting connective tissue, d and e. Elsewhere the nerve-fibres alone are repre- 

 sented; c, enveloping pia mater. 



other fibres of all the spinal nerves. From the sides of the 

 gray substance fibres continually pass out into the white 

 portion and become medullated; some of these enter the 

 gray network again at another level and so bring parts of 

 the cord into especially close union, while others pass on 

 into the brain. At the top of the neck, moreover, the 

 gray matter of the cord is continuous with that of the 

 .medulla oblongata and through it with the rest of the 

 brain, so that nervous disturbances can pass by anatomi- 

 cally continuous paths from one to the other. 



