jro. Journal of Comparative Neurology. 



The number of fibers selected at each level varied accord- 

 ing to the proportion of fibers present at that level. In meas- 

 uring the largest fibers in the branches, a number of fibers 

 equal to the number of fibers measured at a level just above 

 the branches was selected and their average area computed. 

 A isecond computation for the proportional number of fibers in 

 the branches was then undertaken. Both results are included 

 in the tables. 



B. Number of Nerve Fibers. 



I... Enumerations at the various levels of the sciatic and crural 

 nerves, and of the thigh and shank branches at their points 

 of separation from the main trunks. 



In ascertaining the number of nerve fibers at different 

 levels for this frog, the first count was made at a point in the 

 sciatic and crural nerves above their branches to the thigh, at 

 the points C and Sj , Figure 2. The next level selected was in 

 the sciatic nerve immediately, below its branches to the thigh, 

 atS„ .- As the crural nerve sends all its fibers to the thigh tis- 

 sues, the sum of the numbers at the first level gave the total 

 number of fibers which innervate the thigh, shank and foot. 

 That at the, second level indicated the number passing on to 

 the shank and foot, while the difference between the numbers 

 at the two levels gave the calculated number of fibers inner- 

 vating the thigh. 



Reference to Table V gives the desired counts. The crural 

 nerve for the left side supplies 1630 fibers, for the right side 

 1.627 fibers to the thigh. The sciatic nerve above its branches 

 to> the. thigh shows for the left side 5499 fibers, for the right 

 adc 5480 fibers. This gives a total count of 7129 fibers for 

 the left side, 7107 fibers for the right side. The number of 

 fibers at S^ , below the branches to the thigh is for the left side 

 3962 fibers, for the right side 3942 fibers. By process of sub- 

 traction the probable number of fibers innervating the thigh is 

 found to be for the left side 3167 fibers, for the right side 3165 

 fibers. 



