CoGHiLL, Cfanial Netves of Amblystoina. 215 



and there is always a possibility of its entire innervation com- 

 ing from the fifth nerve indirectly through the sixth. Yet, as I 

 have already pointed out, the motor fifth root is widely sepa- 

 rated from the sixth nerve during their course through the 

 ganglion, and none of my preparations show any evidence of 

 fibers passing from one into the other. The trigeminal fibers 

 to the eye muscles cannot be explained as coming from the 

 motor root of this nerve. They must come from the root of 

 the ophthalmicus profundus, though I have observed but one 

 case that gives any evidence whatever for such an hypothesis. 

 In this case, in which motor fibers elsewhere showed a differen- 

 tial stain, medullated fibers could be traced continuously 

 through the ganglion from the root to the trunk of the ophthal- 

 micus profundus. Still, I have not distinguished motor axones 

 entering the ophthalmicus profundus portion of the root of the 

 fifth nerve. The exact relations, therefore, of the neurones 

 which innervate the m. levator bulbi in Amblystoma are 

 unknown. 



IV. The Trigeminal, Facial and Auditory Nerves. 



A. the roots and ganglia. 



/. — The Ganglia and Origin of the Roots. 



The roots of the fifth, seventh and eighth nerves leave the 

 medulla by four distinct areas of exit. Three of these areas 

 are at approximately the same transverse level, in which that of 

 the lateralis VII root is dorsal; that of the motor VII root, 

 ventral; that of the auditory and communis VII roots, between 

 the other two. The fourth area of exit belongs wholly to the 

 root of the fifth nerve, and is located some distance anteriorly 

 of the other three and from the extreme lateral margin of the 

 medulla. 



The Gasserian ganglion proper, the ganglion of the ante- 

 rior division of the lateralis VII root and the ganglion of the 

 ophthalmicus profundus V form a fused ganglionic complex 

 which is located intracranially near the anterior end of the ear 

 capsule. The geniculate ganglion lies latero-ventrally and a 



