300 



STUDY OF BRAINS OF SIX EMINENT SCIENTISTS AND SCHOLARS. 



in this direction by my findings in the brains of Major J. W. Powell, concerning whose 

 mental traits I once knew nothing, but whose great parieto-occipito-temporal associa- 

 tion area (particularly in the right or preponderatingly sensory half) led me to venture 

 the presumption that this redundancy probably corresponded to a superior ability 

 to register and compare the impressions in the visual, auditory and tactile spheres 

 (which together form the concept sphere). That INIajor Powell's intimate friends and 

 co-workers corroborated, in general, these presumptions, was indeed gratifying, and I 

 trust that the similar venture in the case of Cope and Leidy meets with like approval. 

 Another interesting somatic expression is to be found in a comparative tabulation 

 of the " cerebro-cerebellar ratio." The cerebro-cerebellar ratio of weight is expressed 

 by the weight of the cerebrum as compared with that of the cerebellum, the latter 

 being taken as 1. By "cerebrum " in this connection is really meant a part of the 

 diencephalon as well, the division of the parts being made by the customary cut 

 passing cephalad of the pons and usually between the pre- and postgemina. In the 

 following list are tabulated the cerebro-cerebellar ratios in the brains of eleven eminent 



and ten ordinary men : 



Table, Cekebro-cerebellar Ratio. 



A glance at the list shows that while in oj-dinary men the ratios cluster around 

 1 : 7.5, among eminent men it is fully a unit higher; that is to say, the cerebrum, or 

 essential-thought apparatus, is relatively more massive, while the somatic organ of 

 motor coordination (cerebellum) remains relatively reduced. 



Certain special studies on the form and size of the callosum in various brains 

 prompt me to introduce some remarks concerning the prevailing ideas about the rela- 

 tive importance of white and gray, matter (or, using more appropriate terms, the alba 



