THE ROOTS OF THE PERIPHERAL NERVES, ETC. 



157 



grow peripherally toward the nerves and centrally in the 

 direction of the spinal cord. 



The centripetal processes form what we call the posterior 

 root. It is, however, joined by fibres which do not originate in 

 the cells of the spinal ganglia. These are apparently the fibres 

 which we see passing to a peculiar group of cells which resemble 



r\mJ i'rf**'-'? *> --Jv- -"^"^Ts^^g-'- " ff- -^- ' V,- v*Hf 



FIG. 94. 



Cross-section of the vesicular column (t>). Pp. funiculus post. 

 (AfterHenle.) 



those of the spinal ganglia. This group, columna vesicularis, 

 or column of Clarke (Fig. 90), lies about at the junction of the 

 anterior and posterior horns. Besides these cells it contains a 

 small bundle of extremely fine nerve-fibres, which run in the 



/ 



long axis of the spinal cord. 



The vesicular column can only be distinctly traced from 

 about the end of the cervical to the beginning of the lumbar 



