SECOND CERVICAL NERVE OF THE RAT 153 
viscero-motor medullated nerve fibers, so that the proportional 
greater pathway for impulses is furnished by the somatic motor 
system. An interpretation of this condition is difficult, since there 
seems to be nothing in the bodily functions of the muscles to 
require or explain richer somatic innervation in the females of a 
given age. In plotting the curve for the number of rats used in 
this investigation there seems to be no association between the 
300 
200 
150 
100 
50 - 
OV 
.~ Fig.6 4H is plotted to show the growth curve of the largest nerve fibers for the 
female rats of each group, and J for the male rats of each group (table 2). 
early checking of body growth in the female and the growth of 
the nerve fiber. The latter goes on as rapidly or more rapidly 
in the female after the checking in rapidity of body growth as it 
does in the male with a more prolonged growth. A comparison 
of fig. 6 with fig. 5 makes this clear. Fig. 5 gives the curve for 
body growth for the two males (G) and the two females (/) of 
each group. Fig. 6 gives the curves for the nerve fiber growth of 
the same rats, H for the females and J for the males. 
