yiS youmal of Comparative JSfeurology and Psychology. 



1. Since the number of medullated nen^e fibers is practically the 

 same for all corresponding cutaneous and articular branches for the 

 two legs, but is much less for the muscular branches of the operated 

 leg than for the muscular branches of the intact leg, the ventral root 

 medullated nerve fibers are distributed chiefly if not entirely by way 

 of the muscular branches. 



2. Of the 2301 dorsal root or afferent medullated nerve fibers in 

 the primary branches of the operated thigh 774, or 34 per cent, were 

 found in muscular branches- and 1527, or 66 per cent, in cutaneous 

 branches. 



3. Of the 1397 dorsal root or afferent medullated nerve fibers in 

 the primary branches of the operated shank 303, or 22 per cent, were 

 found in muscular branches and 1094, or 78 per cent, in cutaneous 

 branches. 



4. Directing our attention to the dorsal root or afferent medullated 

 nerve fibers passing by way of the primary cutaneous branches, we 

 find the number to the thigh has a ratio to that for the shank of 7 : 5. 

 From a previous measurement of the skin areas of the thigh and the 

 shank we find the same ratio of 7 : 5. 



5. A ratio of approximately 8 : 3 was found for the thigh and 

 shank muscle weights by Donaldson and Schoemaker, 1900. The 

 dorsal root medullated nerve fibers in the primary muscular branches 

 of the thigh and shank of the operated leg have the same ratio 8 : 3. 



6. The dorsal root medullated nerve fibers are then distributed to 

 the thigh and the shank in proportion to the mass of tissue inner- 

 vated, that is, the cutaneous in proportion to the area of the skin of 

 the two segments, and the muscular in proportion to the weights of 

 the muscle masses of the two segments. 



7. Among the dorsal root medullated nerve fibers innervating 

 the segments of the leg in the frog, splitting of nerve fibers occurs in 

 both the thigh and the shank. The percentage of distal excess is 10 per 

 cent for the thigh and 28 per cent for the shank, differing but slightly 

 from the excess for the combined ventral and dorsal root fibers in 

 the legs of the control frog IIB. From this it would appear that 

 splitting occurs in both afferent and efferent medullated nerve fibers 

 in the leg of the frog, and in about equal proportions among each. 



