1 88 'Journal of Comparative Neurology and Psychology. 



the body length, of the frogs concerned. It appears from this, 

 that the internodes on the roots of the IX nerve grow as do the 

 internodes in the nerve to the leg. Concerning the limits of the 

 stretch of nerve w^hich v^e have to examine, w^e may feel very sure 

 that in the case of the dorsal root they have been correctly deter- 

 mined. This stretch lies between the spinal ganglion and the 

 point of union of the root with the cord. In the case of the ventral 

 root however the corresponding stretch appears to be between 

 the cord as one limit and the junction of the ventral with the dorsal 

 root as the other, although further observations are necessary to 

 establish the latter limit beyond dispute. 



TABLE 12. 



Showing the length of the nerve roots of the IX nerve, and the average length of 

 the internodes on the fibers in them. The averages v^^ere obtained from random 

 sampHng and are based on the. measurement of_50jfibers in each case. 



In the relations between the diameter of the fibers and the length 

 of the internodes in the dorsal and ventral roots, there are cer- 

 tainly no striking differences, since in the ventral roots the inter- 

 nodal length is on the average 84 times the diameter, while in the 

 dorsal roots it is 87 times. If we compare the length of the inter- 

 nodes on fibers of a given diameter in the ventral and dorsal root 

 and also in the sciatic nerve at the level ^^i in Frog 8 — the only 

 specimen in which the comparison can be made — it appears that 



