Donatpson, Law of Innervation. 245 
must be introduced. The principle involved in making the 
allowance is that the division of any splitting fiber which has 
already been counted asa fiber entering the leg is to be con- 
sidered as additional, and hence added to my estimate of the 
number to the foot. 
For example, the splitting fibers included in the original 
46% of those entering the leg and sending one division to the 
thigh (bi) are pictured as sending the other division to 
the foot. 
This group (b,) contributes 106 fibers to the foot. As 
the fibers representing these divisions have already been ac- 
counted for, they would not appear in my estimate, and hence 
must be added to it. In like manner, the long divisions of the 
splitting fibers which go to the shank come from fibers already 
counted and are therefore additional; thus these also should be 
added to my estimate. The latter group (b,) represents 
46.8% of the splitting fibers which pass to the shank and these 
amount to 145. To the original estimate of 2042, therefore, 
106+145=254 is to be added, making a total of 2293 fibers. 
This number is still 204 fibers less than the observed 2497. 
The difference may justly be credited to the splitting fibers of 
class (a), namely those, both divisions of which have a like 
distribution. That many such splitting fibers occur is shown 
by Dr. Dunn’s observations (1902, p. 314). 
The arrangement of the fibers as here imagined is exhib- 
ited in Figure 3, which is purely a schema. Here the largest 
column represents the fibers going to the thigh, the next 
largest those to the foot and the smallest those to the shank. 
The size of the columns is proportional.to the number of fibers. 
they contain. 
