CHAPTER X 

 THE CEREBRUM 



A STUDY of comparative anatomy shows that, on the 

 whole, there is a gradation in the development of the 

 cerebrum which corresponds fairly well with the degree of 

 intelligence and the variety of reaction which different 

 animals exhibit. In the brain of man this division reaches 

 its most conspicuous rank. For at least a hundred years 

 the correlation of intelligence with the cerebral evolution 

 and especially with the extent of the cortex has been 

 universally accepted. It is said that only two animals 

 have cerebral hemispheres more massive than those of 

 man. These are the elephant and the whale; in both, 

 the great size of the body removes the brain from any 

 comparison with that of man. In fact, the brain of the 

 whale is relatively small. 



Starling says that in proportion as the cerebrum be- 

 comes prominent, the possibility of predicting what re- 

 sponse will follow the giving of a certain stimulus dimin- 

 ishes. The animal is less and less machine-like. This is 

 closely connected with the fact that two animals of the 

 same species can show individual traits to an extent which 

 is determined by the importance assumed by the cerebrum 

 in the reactions of that species. One rabbit does not differ 

 in very many respects from another; two cats are quite 

 unlike and may be said to have character or personality. 

 In Chapter III the point was made that the higher type 

 of nervous system is that in which individual as well as 

 racial acquisitions are stored. We may now add that 

 such storage is the particular though perhaps not the 

 exclusive work of the cerebrum. 



If two persons could exchange their spinal cords, 

 both being in good health, it does not appear that the 



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