112 



NERVOUS SYSTEM OF VERTEBRATES. 



horn itself either at the same level or farther forward or backward. 

 Such cells are seen in Figs. 53, 56. The function of these cells 

 is to spread the incoming impulses more completely to all parts 

 of the nucleus. A part of the neurites of these cells pass across 

 the median plane dorsal to the canal, forming a part of the dorsal 

 commissure of the cord, and end in the dorsal horn of the opposite 

 side (Fig. 53). 



FIG. 54. Transverse section of the substance of Rolando in the cervical cord of 

 the new-born cat. From Cajal (Textura, etc.). A, cells of the vertex of the dorsal 

 horn; D, C, 'cells of the substance of Rolando; E, deep collaterals; F, endings of 

 same; a, neurites. 



The large cells have larger dendrites with long branches which 

 spread through the dorsal horn and the dorsal tracts (Figs. 

 54) 55> 57)- The neurites go ventrally beyond the dorsal horn, 

 either in the gray or the white matter; and, crossing the median 

 line ventral to the central canal, form what appears in transverse 



