Hardesty, spinal Ganglion Cells. 27 



counting. For the three nerves involved here, this table shows 

 that, though the variation is not very regular, the larger speci- 

 mens give the larger numbers. In some of the succeeding 

 tables where the numbers are summed up and arranged accord- 

 ing to the body weight, this fact is more evident. It is one of 

 the features for which Table III is especially constructed. 



In the last column of Table I the number of fibers in the 

 ventral roots are compared with the number in the dorsal roots. 

 The proportional relations are expressed in the form of ratios. 

 It is seen (i) that in every case the dorsal root fibers exceed 

 those in the ventral root ; (2) that in the Vth nerve this excess 

 is greater than in the Vlth while in the Vlth it is greater than 

 in the IXth, and (3) that the ratios do not vary with the varia- 

 tions in body weight. In five cases the dorsal root fibers of 

 the Vth nerve are more than twice the number in the ventral 

 root. In the Vlth there are but two such cases and in the 

 IXth there are none, but in the latter the relation is much more 

 uniform than in either of the other two. The average ratios, 

 computed for each of the nerves, show more readily the differ- 

 ences between the excesses of dorsal root fibers in the Vth and 

 Vlth nerves and the excesses in the IXth. Very similar ratios 

 may be obtained from the numbers pertaining to these three 

 nerves determined in the previous investigation ('99). Both 

 the IXth nerves recorded there show the dorsal roots as having 

 1.5 times as many fibers as the ventral roots, thus agreeing with 

 the average found here. There it was shown that of all the 

 spinal nerves of the frog, only the 1st, Illth and Xth possess 

 an excess of fibers in their ventral roots. That the excess of 

 dorsal root fibers is greater in the Vlth and especially in the 

 Vth than in the IXth nerve coincides with the fact that a greater 

 proportion of their fibers are contributed to the skin than is the 

 case in the IXth. They are much smaller than the IXth and 

 in many cases the number of fibers in their dorsal branches ex- 

 ceeds the number in the nerve trunk (see Table III), and so 

 great a proportion of fibers in the dorsal branches are sensory 

 that the peripheral border of the spinal ganglion may nearly 



