82 



Journal of Comparative Neurology. 



Table shows at a glance that for the heavier frog, there is 

 a decided gain in the excess of the dorsal root fibers. That the 

 percentage of the excess in the IXth nerve fails to show an in- 

 crease is probably due to an unequal distribution of root fibers 

 in the Vlllth, Vllth and IXth nerves. The gain in the VII is 

 more than ample to balance the deficiency. 



To determine whether the relation exhibited by these four 

 nerves is true for the entire ten, we must again draw upon the 

 records of Birge. To determine the increase in the number of 

 fibers with increase in size of the animal, Birge counted the ten 

 nerves of several specimens chosen with reference to their 

 weight. Using his figures for the total numbers of dorsal root 

 fibers and of ventral root fibers found for one side of the speci- 

 men, and computing the percentage of the excesss of dorsal 

 root fibers in each case, we get 



TABLE VII. 

 From Birge — Rana esculenta. 



Weight of 

 frog 



23 grams 

 63 grams 



Total number of 

 dorsal root fibers 



3781 

 5335 



Total number of 

 ventral root fibers 



3 '524 

 4283 



Excess of dorsal 

 root fibers 



257 

 1052 



7-3 

 24.5 



Taking the total number of fibers in each root of the 

 Vlth, Vllth, Vlllth and IXth nerve of the same specimens 

 used in Table VII we get, 



TABLE VIII. 

 From Birge — Rana esculenta. 



Wt. of frog, 



23 grams. 

 63 grams. 



Total number 

 fibers in Dor- 

 sal Roots. 



1930 

 2840 



Total number 

 fibers in Ven- 

 tral Roots. 



1225 

 1612 



Excess of 



Dorsal Root 



fibers. 



705 

 1228 



Percentage. 



5v5 

 76.1 



Thus it is seen that there is an increase in the excess of 

 dorsal root fibers for the larger specimen when we consider 

 the Vlth, Vllth, Vlllth and IXth nerves as well as when we 

 consider the entire ten nerves. 



Then taking the sums of the dorsal root fibers and the 

 sums of the ventral root fibers found in the Vlth, Vllth, Vlllth 



