The Science of the Mind 5V". 



or six times as many nerve-cells as there are human beings in the 

 world, and the complexity of inter-relations is past all telling. 



The cerebellum, or lesser brain, lies at the back of the head, 

 and below it is the medulla, whose functions have been previously 

 explained. We need, not, therefore, further enlarge on the out- 

 line of our nervous system the cerebrum, cerebellum, brain- 

 stem, spinal cord, and nerves. "That marvellous structure, the 

 human brain, is the product of millions of years ; its history begins 

 with life itself." The brain is a republic of nerve centres; each 

 part has its own peculiar function and all in inter-action. 

 There are parts of the brain whose function is unknown parts 

 which we believe serve for memory, judgment, and imagination. 

 There is reason to suppose that one part is the seat of the processes 

 associated with remembrance of articulation; that another is 

 similarly associated with memory of the sound of words; yet 

 another part of the brain is associated with visual images of words 

 and letters. 



There is no lobe in the brain that is the seat of intelligence. 

 It is the whole cortex, we might almost say the whole nervous 

 system, or the whole body, that is concerned in intelligence, not 

 any single region of it. It is by the plasticity, the power of 

 adapting itself to new ways of learning, registering, and re- 

 peating new co-ordinations of actions, that the brain is marked 

 out from the rest of the body and even from the rest of the 

 nervous system. Great ability, great intelligence even, are not 

 dependent primarily on the brain. 



1 



Mind in Evolution 



When we look back over the vaguely discerned evolution of 

 Animal Behaviour, we find that it had its starting-point in the 

 tentative movements of simple creatures, as has been explained in 

 a previous chapter. We see such tentative movements in the very 

 lowliest creatures (see Vol. I., p. 76). 



