376 Some Racial Peculiarities of the Negro Brain 
left side to be more prominent at this point, but extreme Negro brains 
that approach the Caucasian brain in type have a larger gyrus frontalis 
inferior and extreme Caucasian brains that approach the Negro brain 
in type have a smaller gyrus frontalis inferior. Of course this difference 
may be due to the anterior association center or to the motor area, in- 
crease in the size of either causing the gyrus frontalis inferior to bulge. 
It is interesting to note in this connection relatively to the arbitrary 
line in Charts III and IV, that all the adult male mulattoes (3) are above 
the line on each side, while all the female mulattoes (4) are below, ex- 
cept on the left side. Only three (of 26) female Negroes are above the 
line on the left side, and five on the right side, and all of these are close 
to the line. Only four (of 35) male Caucasians are below the line on 
the right side, and three on the left side, and these are all near the line. 
This indicates a divergence in the males of the two races and a conver- 
gence in the females. Evidence of the same relation is obtained from 
Table II? in the index of the association centers, the Caucasian male be- 
ing 98-97; the Negro male, .90-89; the Caucasian female, 96-97; and 
the Negro female, 91-91, for the left and right sides, respectively. This 
fulfills the biological law that the females are more homogeneous, the 
males more heterogeneous, the latter being more apt to vary from the 
type, or to be extreme. 
A slight difference from that found in the association centers is found 
in the frontal and parietal lobes of the brain in relation to the means. 
A table is given for comparison, which is derived from Charts III and 
IV in the same way that Table II¢ is derived from Charts I and II. 
TABLE IIIb, 
MEANS OF THE FRONTAL AND PARIETAL LOBES. 
Left Side. Right Side. 
as aN fs wos ae 
aoe ee a2 3s 
Sembol Ss £2 Differenceofthe #3 £2 Difference of the 
pyzahos: ae 2S combined means. ad Do combined means. 
Sais af: £E ao 
moO os 2) Aas 
Caucasian. seas Od 69 72—T0=2 66.5 69.5 72.5 — 70 =2.5 
INGETOM ye tee cietavere 63.5 - 68:5 7o—7T0=5 63.5 68.5 (3 — (VS 
On comparing this table with Table II°, it is found that the differences 
are similar, but mot so great. The inferences are that the frontal lobes 
are smaller in the Negro than in the Caucasian, but practically the same 
size on the two sides in each race; that the parietal lobe is slightly larger 
in the Caucasian than in the Negro, but practically the same size on the 
