222 



ALBERT KUNTZ 



The spinal nerves are composed of bundles of parallel fibers 

 accompanied by numerous cells which/as will be shown presently, 

 are obviously of medullary and ganglionic origin. These cells 

 are present both at the surface of the bundles and among the grow- 

 ing fibers in the interior of the nerve-trunk. They are easily 

 distinguished from the cells of the surrounding mesenchyme by 

 their larger size and the characteristic chromatin structure of 

 their nuclei. 



In embryos 9 mm. in length, the anlagen of the sympathetic 

 trunks may be traced from the cervical to the sacral region. The 



@ c § 



9 9 





9 f • K t , * * 

 • #£ § § i ^ 



4 % + . 



XT 



Fig. 2. Section showing the path of the communicating ramus in an embryo 

 10 mm. in length, X 200. 



cells have become more numerous and more closely aggregated. 

 Fibers are present in the communicating rami, but do not yet 

 extend into the anlagen of the sympathetic trunks (fig. 1, c.r.). 

 "Accompanying" cells are present all along the spinal nerves and 

 the communicating rami. At the tips of the growing rami, cells 

 appear to become detached and to wander into the anlagen of 

 the sympathetic trunks in advance of the growing fibers (fig. 1, 

 i.e. c.r.). 



In embryos 10 mm. in length, the fibers of the communicating 



