XXX.] 



SPINAL CORD. 



335 



large multipolar nerve-cells, arranged in groups which does not 

 reach the surface of the cord, and a posterior cornu with a few 

 small nerve-cells which conies to the surface, and is prolonged into 

 the posterior root. At the hinder part of the posterior cornu, an oval, 

 deeply stained part, the substantia gelatinosa. A neck connecting 

 the two cornua. There is also a 

 group of nerve-cells placed laterally 

 in the grey matter, the vesicular 

 column of Clarice (fig. 318). In 

 the anterior horn, note especially 

 the entrance of the fibres of the 

 anterior nerve-root and the large 

 multipolar nerve-cells (fig. 315). 



(/.) Connecting the two halves 

 of the cord, the anterior and 

 posterior commissures, running 

 between the grey matter of 

 opposite sides, and in the middle 

 between them the central canal, 

 which is surrounded externally 

 by a deeper stained layer of 

 neuroglia. 



(g.) In front of the anterior 

 grey commissure is the anterior 

 white commissure, with large medullated fibres crossing each other 

 at an angle. 



(h.) (H) The pia mater surrounding the white matter. The cut 

 ends of the medullated nerve-fibres of various sizes. In the centre 

 of each circular area the stained 

 axis-cylinder, surrounded by a 

 concentric clear area the white 

 substance of Schwann (fig. 316). 

 In a preparation hardened in 

 chromic acid not infrequently a 

 number of concentric lines are 

 seen in the myelin. Between 

 the fibres here and there the 

 neuroglia, composed of glia cells. 

 On the surface of the cord there 

 is a thin layer, in which the fibrils 

 of the neuroglia can readily be seen. 



tions, as fine septa, of the deeper part of the pia into the 

 siibstance of the cord. The larger septa carry blood-vessels. 

 The nerve-fibres of the antero-lateral columns are generally 

 larger, i.e., broader, than those of the posterior column, while those 



FIG. 315. Entrance of Anterior Root into 

 the Anterior Cornu of Lumbar Region, 

 i. Part of anterior white column ; 2. 

 Anterior grey matter with four multi- 

 polar cells ; a, a'. Two rootlets, x 30. 



FIG. 316. T.S. White Matter of Cord. 

 a. Peripheral layer ; b. Septum ; c. 

 Branched glia-cell ; the remainder 

 nerve-fibres, small and large, x 150. 



Note also the prolonga- 



