162 



NERVOUS SYSTEM OF VERTEBRATES. 



nucleus to end in the neighboring motor column, from which 

 arise the viscero-motor nerves. These fibers constitute what 

 may be called short viscero-motor connections. The remaining 

 cells are cells of moderate size whose neurites go directly latero- 

 ventrad and near the surface of the medulla either bifurcate into 



FIG. 83. Transverse section through the medulla oblongata of a mouse four 

 days old. From Cajal (Beitrage u. s. w.). A, hypoglossal nucleus; B, nucleus 

 commissuralis; C, olive; D, spinal V tract; E, motor roots of IX and X; F, 

 nucleus ambiguus; G, caudal portion of the nucleus of the descending root of the 

 nervus vestibularis; H, fasciculus solitarius; a, pyramids; /, general cutaneous 

 components in IX and X ( ?) ; h, collaterals of fasciculus solitarius ending in its 

 accompanying nucleus. 



cephalic and caudal branches or run forward or backward with- 

 out dividing. The descending fibers form a diffuse bundle which, 

 after giving part of its fibers to a nucleus adjacent to the nucleus 

 commissuralis (bony fishes), grows smaller caudally and is lost 



