Dunn, Nerve Fibers of the Frog. 



313 



shank. The fourth level cuts, at a point opposite the ankle, 

 the four subdivisions of the tibial and peroneal nerves which 

 supply the tissues of the foot. This level lies only slightly 

 below the point at which the last branches to the shank are 

 given off. 



The total number of fibers at the third level is for the left 

 side 4146 fibers, for the right side 4152 fibers. The total num- 

 ber of fibers at the fourth level is, as has been shown in Table 

 VIII, for the left side 2486, for the right side 2497. 



The total number at the third level less the total number 

 at the fourth level gives the calculated number of fibers to the 

 shank, which is 1660 for the left side, 1655 for the right side. 



TABLE IX. 



Showing the calculated number of nerve fibers innervating the 

 shank. 



Frog II B. 



2. Significance of the excess of the observed over the calculated 



number of fibers to both thigh and shank. 



A comparison of Tables V and VI, relating to the fibers 

 innervating the thigh, with Tables VII and IX, relating to the 

 fibers for the shank, reveals a surprising discrepancy between the 

 observed and the calculated number of fibers in each instance. 



Table X, exhibiting the differences for the thigh, shows 

 for the left side an excess of 314 fibers or 9% of the number 

 of fibers concerned in innervating the thigh, for the right side 

 343 fibers or nearly 10% of the observed number of fibers 

 innervating the thigh. 



