74 ORGANIC EVOLUTION 



development. Thus stated, the hypothesis is seen 

 to be reduced to an absurdity. The prime author 

 of the chain of events is not the initiative of the 

 cranial sutures, but the initiative of the brain itself. 

 In other words, the cranial sutures close later in 

 man, because the brain of man undergoes a longer 

 and greater development than does that of the ape. 

 [ do not here outline any of the highly speculative 

 ideas that are advanced in explanation of this more 

 prolonged development of the human brain. The 

 subject is fascinating, but our knowledge of it too 

 unsure for discussion here. We merely assert that 

 the hypothesis which alleges the all-controlling 

 brain to be at the mercy of the cranial sutures is 

 radically unsound, essentially absurd, and must be 

 incontinently rejected. 



The second difference in brain-proportion between 

 man and the anthropoid ape has regard to the 

 superficial grey matter which contains the nerve- 

 cells and is the essential part of the brain. In man 

 we find this layer of grey matter to be thicker ; we 

 find that the fissures, into which the grey matter 

 always dips, are deeper and inuch more subdivided. 

 Thus the brain of man contains a far larger number 

 of nerve-cells than the brain of the ape. 



The third difference in brain-proportion between 

 man and the ape has regard to the mutual pro- 

 portions of different parts of the brain. There is 

 some truth in the popular notion that a high fore- 

 head is connected with high intelligence. There is 

 probably still more truth in the notion — expressed 

 by Tennyson when he speaks of "the straitened 

 forehead of the fool" — that a broad forehead is 



