40 Journal of Comparative Neurology and Psychology. 



comparison of their numbers alone shows that the dorsal 

 branches contain many fibers which have nothing to do with 

 forming the distal excess for in every case here the dorsal 

 branches themselves contain at least a few more fibers than 

 comprise the distal excess. However, in the nerves formerly 

 dealt with it was found possible in some of the larger nerves, 

 for the distal excess to exceed the amount of the dorsal branches 

 thus making it necessary, in those cases at least, that some of 

 the distal excess be contained in the trunk. The percentage 

 relations of the amount of the distal excess to the amount of 

 the dorsal branches are shown in column M. In this it is seen 

 again that the distal excess increases at a more rapid rate than 

 the number of fibers in the dorsal branches, though the pro- 

 gression is not so constant as in some of the other cases. If 

 the fibers of the dorsal branches alone are concerned to any 

 great extent in forming the distal excess, the relation of their 

 number to the number composing both the trunk and dorsal 

 branches should be somewhat similar to the same relation main- 

 tained by the amount of the distal excess. In column O such 

 relations of the dorsal branches are expressed in percentages 

 and when they are compared with the same values for the dis- 

 tal excess (col. N) the variations of the two are not very simi- 

 lar. Rather, a more fixed proportion is manifest, the dorsal 

 branches comprising approximately 19% of the fibers on the dis- 

 tal side of the ganglion up to 47 grams at which specimen the 

 proportion suddenly changes to 24%. 



8. Certain of the excess of cells in the spinal ganglion 

 above the number of fibers in the dorsal root may take part in 

 contributing to the distal excess. In column P are given the 

 numbers of cells in the spinal ganglia in excess of the fibers in 

 the respective dorsal roots and in the last column of the table 

 the relations of the fibers of the distal excess to these extra 

 cells are expressed in the form of ratios. Though it appears 

 that the cells themselves increase with the increase in weight, 

 the increase of the fibers in the distal excess is such that while 

 in the youngest specimens there are twelve times as many cells 

 as fibers, in the 47 gram frog there are only six times as many. 



