CoGHiLL, Cranial Noues of Amblystovia. 233 



Upon leaving the medulla the root of the ninth nerve (AY) 

 comes in contact with the ventral side of the lateralis root of the 

 vagus and holds this relation with it until the two nerves ap- 

 proach the ganglion. The root of the ninth then passes more 

 laterad then the other, and enters the anterior portion of the' 

 ganglionic complex. Its ganglion extends ventrad and laterad 

 and forms the anterior end of the complex. It supplies the 

 communis component of the truncus glossopharyngeus. The 

 entire motor component also enters this trunk. 



In the older larval stages and in the adult the two roots 

 just described leave the cranium by a distinct foramen of their 

 own. In these stages, also, the ganglion of the glossopharynge- 

 us extends a considerable distance out on the trunk and seems 

 to have a tendency to become constricted off from the rest of 

 the complex. 



7. — TJie Second Root of the Vag2is. 



The second root of the vagus leaves the extreme lateral 

 border of the medulla at a transverse level which is consider- 

 ably posterior of the exit of the ninth nerve. It is composed 

 of motor and communis fibers. It turns caudad and meets the 

 third root of the same nerve just before entering the ganglionic 

 complex. As the two roots enter the complex the second root 

 passes dorsally of the third, while its ganglion lies ventrally of 

 the lateralis ganglion and posteriorly of the ganglion of the 

 glossopharyngeus. 



The motor fibers, at the proper stage of myelination, may 

 be traced through the complex from the second root of the 

 vagus into the first and second branchial trunks of the vagus. 

 The communis component of these trunks is also deriv^ed from 

 this root. It is impossible, however, to say whether neurones 

 of this root enter the truncus visceralis. The ganglion of the 

 root seems to extend caudad and send fibers into the truncus 

 visceralis, but it is possible that this caudal extension of the 

 ganglion belongs to the communis component of the third root 

 of the vagus. 



