194 THE DESCENT OF MAN. 



ter, which for the want of a better term are often called spon- 

 taneous. Nor do I pretend that the effects of sexual selection cai; 

 be indicated with scientific precision; but it can be shown that 

 it would be an inexplicable fact if man had not been modified by 

 this agency, which appears to have acted powerfully on innumer- 

 able animals. It can further be shown that the differences be- 

 tween the races of man, as in color, hairiness, form of features, 

 &c., are of a kind which might have been expected to come under 

 the influence of sexual selection. But in order to treat this sub- 

 ject properly, I have found it necessary to pass the whole animal 

 kingdom in review. I have therefore devoted to it the Second 

 Part of this work. At the close I shall return to man, and, after 

 attempting to show how far he has been modified through sexual 

 selection, will give a brief summary of the chapters in this First 

 Part. 



NoTB ON" THK Resemblances and Dipfbkences in the Structure 

 ASD TPiE Development of the Beain in Man and Apbb. 

 By Professor Huxlet, P.E.S. 



The controversy respecting the nature and the extent of the 

 differences in the structure of the brain in man and the apes, 

 which arose some fifteen years ago, has not yet come to an end, 

 though the subject matter of the dispute is, at present, totally 

 different from what it was formerly. It was originally asserted 

 and re-asserted, with singular pertinacity, that the brain of all 

 apes, even the highest, differs from that of man, in the absence of 

 such conspicuous structures as the posterior lobes of the cerebral 

 hemispheres, with the posterior cornu of the lateral ventricle and 

 the hippocampus minor, contained in those lobes, which are so 

 obvious in man. 



But the truth that the three structures in question are as well 

 developed in apes' as in human brains, or even better; and that 

 it is characteristic of all the Primates (if we exclude the Lemurs) 

 to have these parts well developed, stands at present on as secure 

 a basis as any proposition in comparative anatomy. Moreover, it 

 is admitted by every one of the long series of anatomists who, of 

 late years, have paid special attention to the arrangement of the 

 complicated sulci and gyri which appear upon the surface of the 

 cerebral, hemispheres in man and the higher apes, that they are 

 disposed after the very same pattern in him, as in them. Every 

 principal gyrus and sulcus of a chimpanzee's brain is clearly rep- 

 resented in that of a man, so that the terminology which applies 

 to the one answers for the other. On this point there is no dif- 

 ference of opinion. Some years since. Professor Bischoff pub- 



