THE ROOTS OF THE PERIPHERAL NERVES, ETC. 



155 



lateral group in front, and, behind the latter, a central group. 

 In the cervical cord there is also a group in the lateral horn. 



On making a longitudinal section we see that these cells 

 are somewhat more plentiful opposite the entrance of each root ; 

 that is to say, they are arranged in segments. We call such an 

 aggregation of cells, together with the root arising from it, a 



FIG. 92. 



From the anterior border of a section through the anterior horn of the gray matter. 

 Passage of the cell processes into nerve-roots. Uarrnine stain *$&. (After Henle.) 



segment of the spinal cord. In human beings the segmentation 

 of the cord is almost obliterated, but it is more pronounced in 

 the lower animals. 



Nothing is certainly known as to the course of those pro- 

 cesses of the ganglion-cells which do not terminate in axis- 

 cylinders: a few appear to extend directly to other ganglion- 

 cells ; the majority, however, are lost in a fine net-work of most 



