Dunn, Medullated Nerve Fibers. Ill 



to the number of ali'ereiit medullated fibers. The number of afferent 

 medullated nerve libers is slightly less than half the total number 

 of medullated nerve fibers in a muscular branch. 



If we attempt to correct for the lost fibers by comparison with, the 

 numbers of cutaneous and muscular nerve fibers found in the various 

 segments of frog IIB, not by an attempt to scale the entire number 

 of nerve fibers to those for frog IIB, our results are as follows : 



The average number for the cutaneous nerve fibers of the two 

 thighs of frog IIB is 1677 nerve fiberSj see Table VII. The average 

 number for the muscular nerve fibers for the two thighs is 1818 nerve 

 fibers. The average number for the cutaneous nerve fibers for the 

 two thighs of frog E is 1540 nerve fibers. The corrected number of 

 muscular nerve fibers for frog E is represented by the sign x. Our 

 proportion then will stand, the number of cutaneous nerve fibers of 

 frog IIB : the number of muscular nerve fibers of frog IIB : : the 

 number of cutaneous nerve fibers of frog E : the corrected number 

 of muscular nerve fibers of frog E. For the thigh the proportion 

 will stand 10)77 : 1818 :: 1.540 : (16G9) x. The number of muscular 

 nerve fibers counted in the thigh branches of the right leg of frog 

 E is 1597 nerve fibers. This number is less by 72 nerve fibers than 

 the number estimated by the proportion, 1669 nerve fibers. In pro- 

 portion to frog IIB the number of medullated nerve fibers to the 

 muscular branches of the right thigh of frog E should be increased 

 by 72 nerve fibers, making the total number of medullated nerve 

 fibers to the muscular branches of the right thigh of frog E 1669 

 nerve fibers. The afferent fibers segregated in the left thigh number 

 774, and the difference between 1669 and 774 gives us 895, the num- 

 ber of efferent medullated nerve fibers to the thigh of frog E. This 

 corrected number would decrease the fraction of medullated afferent 

 fibers in the total number of medullated nerve fibers to the thigh, but 

 the number would not be reduced to the one-third sometimes found 

 by Sherrington, 1894. 



Correcting in the same way the muscular nerve fibers to the shank 

 of frog E we have 1193 : 928 : : 1093 : (844) x. The number found by 

 actual count is 601, and the difference between 844 and 601 is 303, 

 giving us 541 as the corrected number of efferent nerve fibers for the 

 shank. 



