76 JouURNAL OF COMPARATIVE NEUROLOGY. 
6. The number of nerve fibers per sq. mm. of the cross- 
sections may vary considerably in the different fascicles of the 
same dorsal spinal root. 
In the following Figures (2-32) are given the projections of the 
dorsal roots of the spinal nerves of man. Their magnification is 34 
diameters. Within the outlines of each fascicle are found two num- 
bers; the first designating the number of the fascicle, and the second 
the number, in thousands, of the nerve fibers per sq. mm. of its 
cross-section. Thus in C.I there is but one fascicle and this has 13.6 
thousands or 13,600 nerve fibers per sq. mm. of its cross-section. In 
a few of the outlines of the fascicles is found the letter ‘‘c.” This is 
to signify that the fascicle was found to be cut obliquely, and that the 
number indicating the nerves per sq. mm. is that of some neighboring 
fascicle, and that the corrected area of this fascicle was obtained by 
dividing the number of fibers in the fascicle by this number of fibers 
per sq. mm. The outlines are always those of the uncorrected pro- 
jections. In the Tables (II-X XXII) accompanying the projections 
are found the data for each root. These tables have four columns of 
figures; in the first, is found the number given to each fascicle; in the 
second, the area in sq. mm. of the cross-section of each fascicle; in 
the third, the number of nerve fibers counted in the cross-section of 
each fascicle; and in the fourth, the number, in thousands, of nerve 
fibers per sq.mm. of the cross-section of each fascicle. In cases 
where a fascicle was found to have been cut obliquely, and its area 
has been corrected, the number indicating the corrected area is placed 
in the column itself (the second) and the number indicating the uncor- 
fected area after it in parenthesis. At the bottom of the table are found 
the totals. These totals have been brought together in Table I° . 
