viii PREFACE. 



and, among my senior contemporaries, men like 

 Lyell, regarded by many as revolutionaries of the 

 deepest dye, were strongly opposed to anything 

 which tended to break down the barrier between 

 man and the rest of the animal world. 



My own mind was by no means definitely made 

 up about this matter when, in the year 1857, a 

 paper was read before the Linnaean Society " On 

 the Characters, Principles of Division and Primary 

 Groups of the Class Mammalia," in which certain 

 anatomical features of the brain were said to be 

 " peculiar to the genus Homo," and were made 

 the chief ground for separating that genus from all 

 other mammals, and placing him in a division, 

 " Archencephala," apart from, and superior to, all 

 the rest. As these statements did not agree with 

 the opinions I had formed, I set to work to rein- 

 vestigate the subject; and soon satisfied myself 

 that the structures in question were not peculiar to 

 Man, but were shared by him with all the higher 

 and many of the lower apes. I embarked in no 

 public discussion of these matters; but my atten- 

 tion being thus drawn to them, I studied the whole 

 question of the structural relations of Man to the 

 next lower existing forms, with much care. And, 

 of course, I embodied my conclusions in my teach- 

 ing. 



Matters were at this point, when " The Origin 

 of Species " appeared. The weighty sentence 

 " Light will be thrown on the origin of man and 



