244 JOURNAL OF COMPARATIVE NEUROLOGY. 
TABLE XX. 
Showing the number of fibers to be added to the original 25.3% in 
the case of Frog B II—Shank. 
Calculated numbers. Observed number 
Original 25.3% of 7107 or 46.8% of 3838 = Tos 
Fibers splitting in branches (Class a) = 155 
Splitting fibers with double representa- 
tion (Class b) = 165 
2116 2130 
Difference —= —1Z¢4 fibers or 0.6% 
The approximation between the estimated and observed 
numbers is not so close here, but is still fair, being within less 
than one per cent. 
The number of fibers to the foot has still to be considered. 
In the case of the foot, the observed numbers are taken from 
the enumeration at the levels P1+P2 and T1+T2. Figure 2. 
These levels would correspond to those just above the branches 
in the case of the thigh and shank. We have to assume, 
therefore, that in the number observed by Dr. DuNN at these 
levels as going to the foot, there are in addition to the single 
pathways represented by fibers that pass unsplit from their 
entrance into the leg, two other classes, those namely (a) that 
have split within the trunk, both divisions descending to the 
foot, and (b) all other split fibers, one division of which goes 
to either the thigh or shank, while the other goes to the foot. 
Of the class (b), there are in the entire leg at least three 
groups: bi, the fibers which split, one division passing to the 
thigh and the other to the foot; bs, fibers which have split, 
one division going to the thigh and the other to the shank; 
bs, splitting fibers which have one division going to the shank 
and one to the foot. 
These several groups are all marked, Figure 3, as in bi, by, 
bs. At the level where the nerves enter the foot, it is neces- 
sary to make allowance for groups bi and bs of class (b), as 
well as for representatives of class (a). 
According to formula, 2042 fibers pass into the foot. Dr. 
Dunn observed 2497. To make the estimated number com- 
parable with that observed, the allowance for the splitting fibers 
