Anatomical Characters of the Human Brain. 9 



the negro brains separated ahiiost completely from the white brains, 

 in Bean's Chart VII, and this line of separation I have inserted at 

 the proper place in my chart, Fig 1. 



I have tabulated as Bean did the area of the genu with that of 

 the splenium in 106 brains and do not find that the symbols for 

 the brains of the two races separate. Most of the negro brains in 

 my chart are intermixed with the white brains above the line which 

 separates them in Bean's chart. My measurements were all made 

 by tracing the outline of the corpus callosum with the very accurate 

 projecting apparatus made by Hermann of Zurich, while Bean's 

 were made with a less precise instrument borrowed from the Smith- 

 sonian Institution. The areas of both Bean's and my own were made 

 with a Conradi planimeter whose minimum registration is 10 sq. mm. 

 and its probable error was found to be 10 sq. mm. In order to 

 exclude my own personal equation, which is an item of considerable 

 importance in a study like this, all of the tracings as well as the 

 measurements of all of the areas were made without my knowing 

 the race or sex of any of the individuals from which the brains 

 were taken. The brains were identified from the laboratory records 

 just before the results were tabulated. 



Tabulation of the brain weight with the area of the cross section 

 of the corpus callosum confirms what Bean found, that is, the area 

 increases with the brain weight. The same is true when the area 

 of the corpus callosum minus that of the splenium is tabulated with 

 the weight of the frontal lobe. However, there are great individual 

 variations, but they seem to be of like extent in both the white and 

 the negro brains. The female records separate somewhat from the 

 male, but this is due no doubt to the lighter weight of the former. 



My figures do not confirm Bean's result that the genu is relatively 

 larger and the splenium relatively smaller in the white than in the 

 negro brain. The specimens I examined include 18 brains which 

 Bean studied, and I find that the measurements I made of the areas 

 of the genu and splenium in them do not agree altogether with his. 

 Ten of the specimens are white and eight negro brains. In making 

 the comparison a deviation of 10 sq. mm. is overlooked, for this 

 error is to be expected from the planimeter we employed. The genu 



