232 STUDY OP BRAINS OF SIX EMINENT SCIENTISTS AND SCHOLARS. 



other brains, but particularly of the right (or preponderatingly sensory) half as com- 

 pared with the left. 



In the mental life of man the power of speech plays so important a part that I 

 will brietl}^ refer here to its chief anatomic relations. The evolution of the faculty of 

 speech has been admirably epitomized by Cunningham in the following words : 

 "Some cerebral variation, probably trifling and insignificant at the start, and yet 

 pregnant with the most far-reaching possibilities, has in the stem-form of man con- 

 tributed to that condition which rendered speech possible. This variation, strength- 

 ened and fostered by natural selection, has in the end led to the great double result 

 of a large brain with wide and extensive association-areas and articulate speech ; 

 the two results being brought about by the mutual reaction of the one process upon 

 the other." 



Let us examine briefly the evidences of cerebral research which bear upon the 

 brain-centers directly concerned in the speech-faculty. In the first place, the center 

 for articulate speech, meaning thereby the center for the control of the tongue and 

 other muscles employed in articulation, has been localized in the subfrontal gyre and 

 adjacent portion of the precenti'al, in the left hemicerebrum in right-handed persons 

 and in the right half in left-handed persons. Nearly all observations upon this region 

 agree in ascribing a superior development with reference to size and diflferentiation in 

 the brains of intellectual persons. Further than this, Riidinger, Schwalbe, Kupflfer 

 and others have found the corresponding region in the skulls of eminent men gifted 

 with a superior command of language (Wiilfert, Huber, Kant) to bulge more on the left 

 than on the right side. 



A region which I believe, however, to be of not a little importance with reference 

 to the intellectual powers, particularly that of speech, is the insula. This is the pur- 

 est association center in the brain and its surface-configuration is somewhat of an index 

 of the degree of development of the general cerebral surfaces, particularly of those 

 parts which are more or less in juxtaposition with it and more or less intimately con- 

 nected with it functionally. Not only is the insular cortex the thickest in the cere- 

 bral mantle, but the abundance of the fusiform cells in the deepest layer has given 

 origin to the claustrum and the arcuate association fibers connected with these cells 

 are so numerous as to give origin to the paraclaustral lamina or capsula extrema. 

 This massive system of association neurones and tracts connecting the receptive sense- 

 areas (chiefly the auditory and visual) related to the understanding of the written and 

 spoken word with the emissary centers for articulate speech is most highly developed 

 in the brain of man and one is justified in assuming that in this region language is 

 organized into propositions and arranged for outward projection ; it may be termed a 



