Anatomical Characters of the Human Brain. 7 



brain substance in women and in men, attempts have been made to 

 show that in the brains of negroes as well as in those of men of 

 genius similar distinctions can be found. In general the differences 

 in weight between each of these three classes of brains is fully 100 

 grams, and if it were shown that the proportion of their parts is 

 different in each class it would be a discovery of great importance. 

 The smaller frontal lobe in women and in negroes, and the larger in 

 men of genius would prove, it is believed, that this portion of the 

 brain is the chief seat of a good mind. It appears, however, that 

 no such unequal distribution of brain substance exists. 



A few years ago the startling announcement was made by Spitzka^^ 

 that the area of the cross section of the corpus callosum was larger 

 in eminent than in ordinary men, that of Leidy being 10.6 sq. cm. 

 Since the corpus callosum is associated mainly with the frontal lobe 

 the observation, if correct, would be of great significance. The ques- 

 tion was immediately tested^^ by comparing in over 150 white and 

 negro brains the area of the cross section of the corpus callosum 

 with the brain weight and it was found that these characters varied 

 with each other (see Bean, Chart V).^^ Since the average weight 

 of the brain of eminent men is about 100 grams heavier than the 

 average brain weight of ordinary men, and since the average negro's 

 brain is 100 grams lighter, the error of Spitzka is easily explained, 

 for in making his comparison he did not take brain weight into con- 

 sideration. According to Spitzka the brains of "notable men pos- 

 sessing large capacity for doing and thinking much more than their 

 fellows," "compared with ordinary men, individually and collectively, 

 have larger callosa. The callosum of Joseph Leidy exceeds in cross- 

 section that of any other in this series or recorded in literature. 

 Here again, then, we have an index in somatic terms of how we may 

 distinguish the brain of the genius or talented man from that of 



"Spitzka. Connecticut Magazine, 1905, and Proc. Amer. Assoc. Anat., 

 Amer. Jour. Anat, 1905. 



"Bean. Amer. Jour. Anat, Vol. 5, 190G. 



^"Spitzlva has not mentioned Bean's observation in his last monograph in 

 the Trans, of the American. Philosoph. Soc, XXI, 1907. Bean compares area 

 of the corpus callosum with the volume of the brain, which is statistically 

 objectionable, but the point made is strong enough to question seriously 

 Spitzka's statement. 



