ROOTS OF THE VAGUS GROUP. 93 



cells of the same character lying close to the median line 

 ventrally of the fasciculus longitudinalis dorsalis. It is 

 partly embedded in, but chiefly dorsally of the commissura 

 accessoria (614-61 1). Its fibres were not traced, 



a. — The motor vagus derives its fibres mainly from the 

 nucleus ambiguus of the same side. It receives some 

 fibres from the commissura accessoria which probably 

 come in part from the nucleus ambiguus of the opposite 

 side and in part from the fasciculus longitudinalis dorsalis. 



The peripheral course of the vagus fibres from the 

 nucleus ambiguus through the ganglionic complex can be 

 followed only with great difficulty on account of the inter- 

 lacing of the root-fibres. After emerging from the 

 oblongata the two motor roots unite in the cephalic face 

 of the great vagus root; they then descend to the ventral 

 surface of the vagus ganglion and here the common trunk 

 divides into two main branches, one directed cephalad, 

 the other caudad. This is clearly the general course 

 followed by most, if not all, of the fibres. Peripherall}^ 

 from the point of divarication of the motor fibres into 

 the several rami they again appear sharply separated 

 from the finer communis fibres and can thereafter be 

 separately traced to their termini. In the ganglionic 

 complex the motor fibres gather in bundles on the ventral 

 surface of the ganglia. These bundles contain both 

 coarse and deeply staining fibres and fine ones which stain 

 feebly and which resemble communis fibres. The former 

 are unquestionably derived from the nucleus ambiguus 

 and can be followed to the striated musculature of the 

 branchial apparatus, etc. ; the latter are probably motor 

 fibres derived from some other source and destined for 

 the unstriated musculature of the oesophagus and viscera. 



Kingsbury ('97, p. 5) describes in Amia fibres entering 



