Dunn, Innervatioji of the Thigh in the Fj'og. 231 



2. Relation of the number of fibers innervating the thigh to 

 the number which innervates the remainder of the leg. 



The first determination of the number of fibers innervating 

 the thigh was made in the following manner : To the number of 

 fibers in a section of the sciatic nerve, S^, just proximal to the 

 branches for the thigh was added the number ot fibers in a sec- 

 tion of the crural nerve. As all the fibers of the crural nerve 

 are concerned in the innervation of the thigh, this section was 

 made at a level just above that at which branching occurred. 

 From this number, which is the sum of all the fibers innervat- 

 ing the entire leg, was subtracted the number of fibers which in- 

 nervate the shank and foot. The latter number was ascertained 

 by a count of a section at S,^, a level of the sciatic nerve distal 

 to the thigh branches. The result of this computation, shown 

 in Table III, gives the calculated number of fibers to the thigh. 



In frog B the left sciatic and crural nerves together contain 



5385 nerve fibers. After the branches to the thigh are given off 



(Sj ) there are found 2974 fibers which pass on to supply the 



shank and foot. The right sciatic and crural nerves of the same 



frog contain 5273 fibers, 2868 of which pass on to the shank 



and foot. The process of subtraction would show that for the 



left side 241 1 fibers, for the right side 2405 fibers had gone to 



innervate the tissues of the thigh, or that in the innervation of 



the thigh fewer fibers were concerned than in innervating the 



remainder of the leg. The computations for frog C show a 



similar relation. 



TABLE IV. 



Showing the number of fibers in the crural and sciatic branches to the thigh 

 and the total number of thigh fibers. 



