Hardesty, spinal Ganglion Cells. 39 



root fibers more nearly keep pace with the changes in the dis- 

 tal excess. It is shown in Table IV that the ventral root gains 

 fibers somewhat more rapidly than the dorsal root. The per- 

 centage variations in the ventral roots of the individual nerves 

 cannot be shown so well in a single column as the sum relations, 

 for, in 6 out of the 14 smaller nerves (the nerves which possess 

 relatively the largest distal excess), the distal excess exceeds 

 the number of fibers in the ventral root. 



6. The variations in the distal excess do not closely coin- 

 cide with the variations in the number of fibers in the trunks 

 and dorsal branches (col's. F, A and B and col's. G and C). 

 Yet when the percentage relations of the sums are considered 

 (col. N) there is again evident a fairly regular and progressive 

 increase. This indicates further that the fibers forming the 

 distal excess increase at a proportionately more rapid rate than 

 the sums of the trunks and dorsal branches in which the excess 

 is contained. The excessive increase is similar to that relating 

 to the two roots though less rapid and somewhat more irregular. 

 In Table IV it is better shown that as the animal grows it gains 

 fibers more rapidly in the trunks and dorsal branches than in 

 the nerve roots. It is indicated here that some of this more 

 rapid gain must take part in forming the distal excess. 



7. As pointed out in the previous papers, the value of the 

 distal excess is dependent upon or somehow correlated with 

 the relative amount of the dorsal branches. Those nerves which 

 have a proportionately large number of fibers in their dorsal 

 branches as compared with the number in the nerve trunk al- 

 ways have a high percentage of distal excess. Most of the 

 smaller nerves of the frog are of this type. Of the 14 smaller 

 (Vth and Vlth) nerves employed here, 6 have dorsal branches 

 containing even more fibers than the trunks themselves (com- 

 pare col's. A, B and H). All of them have higher percentages 

 of distal excess than the IXth nerve. While in the individual 

 nerves (col. B) as well as in the sums (col. L) it is seen that 

 dorsal branches increase with the body weight, the variations 

 do not appear so regular or to closely coincide with the varia- 

 tions in the amount of the distal excess (col's. F and G). A 



