DonaLpson, Law of Lunervation. 255 
From these data it appears probable that in all these frogs 
and in every segment of the leg, some afferent fibers are dis- 
tributed, with the muscular nerves. Moreover, the proportion 
thus distributed is shown to be very variable in the case of 
the thigh. 
On comparing the proportion of these afferent fibers going 
to the muscles in the case of the shank, we find that the num- 
ber is relatively larger than to the thigh. The comparison in 
the case of the shank B II, should be made, not with the data 
for the thighs of all the frogs, but with the data for the thighs 
of frog B II. Thus, in round numbers, there are in this 
instance, 4% of these afferent fibers to the thigh and 45% to 
the shank. 
The better supply of the muscles with afferent fibers as we 
pass to the more distal segments of the limb, is what we 
should expect a priori, though in this case the difference 
appears very large. 
Conclusions. 
The present study is concerned with the number of med- 
ullated nerve fibers going to the different segmengs of the 
frog’s leg. 
1. The nerve fibers entering the leg being considered as 
so many separate lines of connection with the several segments 
are found to. be distributed in accordance with the law that the 
efferent fibers are present in proportion to the weight of the 
muscle, and the afferent in proportion to the area of skin. 
2. When this statement is reduced to numerical terms, it 
is expressed by the following formula: 
Of the fibers entering the leg of the frog, 
46.07%, go to the skin and muscles of the Thigh. 
25.3% go to the skin and muscles of the Shank. 
28.79, go to the skin and muscles of the Foot. 
3. Since some of the fibers split after entering the leg, 
the numbers found in the nerve branches to the segments are 
larger than the number of single pathways assigned to the seg- 
ment by the formula. Calculation shows that to determine the 
number which will probably be observed in each case, the 
