THE VISCERAL AFFERENT DIVISION. 



161 



small column of cells accompanying this bundle. In the mouse 

 (Figs. 82, 83), as in fishes and amphibia, the descending fibers 

 enter the nucleus commissuralis and help to form the commissure. 

 In all classes a part of the fibers continue caudad beyond the 

 commissura infima in the visceral column of the cord. 



In fishes, where these centers are best known, their structure 

 is relatively simple. The terminal branches of the afferent fibers 

 are short but very profusely subdivided and the dendrites of the 

 cells often have the same characteristics, so that sections of this 



FIG. 82. Transverse section through the medulla oblongata of the mouse at the 

 level of the nucleus commissuralis. From Cajal (Beitrage u. s. w.)- A, nucleus 

 commissuralis; B, nucleus of hypoglossus; C, decussation of lemniscus; D, fasci- 

 culus solitarius; b, c, endings of 'fibers of IX and X nerves. 



center prepared by the Golgi method show dense brushes of 

 intricately interwoven fibers which have as a whole a very furry 

 appearance (Fig. 84). Many of the cells are of type II whose 

 neurites terminate within the lobe. In fishes whose gustatory 

 apparatus is largely developed these intrinsic neurones are very 

 numerous. Other cells send their neurites out of the sensory 



ii 



