MOTOR NUCLEI IN PHYLOGENY 



69 



ences as obtain are essentially those of degree and not of plan. 

 The same may be said with regard to the motor IX root, where 

 my observations on Damonia confirm those of Kappers on other 

 reptiles in tracing the origin of this nerve to a nucleus common 

 to it and the motor VII root.*' 



Fig. 5 Damonia subtrijuga. Transverse section through the medulla near 

 the exit level of the motor facial root. Abbreviations: Fib. arc. dors., dorsal 

 arcuate fibers of the octavomotor system; N. VI., abducens nerve; R. VII m., 

 emerging motor facial root; R. VII m. asc, ascending motor facial root fibers 

 cut both transversely, dorsal to the posterior longitudinal bundle, and obliquely, 

 lateral to this structure; Tr. VIII., acustic tract and entering fibers. Other 

 abbreviations as before. 



" Willard (1. c.) makes mention of his inability to make out the central rela- 

 tions of the motor VII and IX roots in Anolis, since his technique was designed 

 primarily to stain peripheral structures. In view of the observations recorded 

 above, it is to be expected that the central relations of these roots in Anolis will 

 be found to conform to the general reptilian pattern. 



