” 
390 Some Racial Peculiarities of the Negro Brain 
to special sense centers in the two hemispheres. Flechsig ” indicates that 
part of the centers for smell may lie in the gyri recti, which are larger 
in the Negro than in the Caucasian. The latter is evidently true from 
what we know about the sense of smell in the Negro, and the size of the 
olfactory apparatus in this race. If the fibers connecting the frontal 
lobes anterior to the motor area are contained in the genu, and a greater 
number of the fibers in the genu connect the olfactory lobes in the Negro 
than in the Caucasian, then the genu of the Negro should be larger. But it 
is really smaller. Consequently the fibers connecting the anterior associa- 
tion centers must be less in the Negro than is indicated by the size of the 
genu. Comparing the areas of the genu and splenium must give an ap- 
proximate comparison of the anterior and posterior association centers. 
They are compared in the two races in Chart VII, made up from Table 
VII. A more definite racial difference is seen in this chart than in 
Charts I and II where the association centers are contrasted from brain 
outlines. A glance at Chart VII convinces that the genu is relatively 
and absolutely larger in the Caucasian than in the Negro. This may also 
be expressed in a table of averages taken from Table VII. 
TABLE VIIa. 
THE RELATION OF THE AVERAGES OF THE AREAS OF THE GENU AND SPLENIUM, 
ETc., IN SQ. CM. 
Number Ratio Ratio 
f 
(0) Genu. Body. Isthmus. Splen- Genu to Body to 
Brains. ium Splenium. Isthmus. 
Caucasian male ..... By vastly ALD 94 1.72 158:100 160: 100 
INGgrommale- 252... -- 60 2.12 1.33 81 1.76 120 : 100 164 : 100 
Caucasian female .... 17 2.41 1.36 Se 61 ASO LOO AS oaO0 
Negro female ....... 25 1.98 Ua aries ale (ey = lala 2X0 AUS LOK) 
The genu is absolutely and relatively largest in the Caucasian male, 
absolutely and relatively smaller in the Caucasian female, absolutely and. 
relatively smaller still in the Negro male, and absolutely and relatively 
smallest in the Negro female. The relations of the splenium are the 
converse of this. The relation of the isthmus to the body is similar, but 
with less marked racial difference. Compare the relation of the ratios 
of the genu to the splenium in the males of the two races (158 : 120 = 
131), with the relation of the ratios of the body to the isthmus (160 : 
164 — 97), and a greater racial difference is evident in the former (131) 
than in the latter (97). This difference is also evident in the females of 
the two. races (150 :115==130. 155 :1603=97). ‘The relation of the 
ratios of the two-lineal halves of the corpus callosum (Table VI®) is 
122 : 102 —119 in the males of the two races, and 110 :100 = 110 in 
