VII " THE ORIGIN OF SPECIES " 233 



And, in view of the facts of geology, it follows 

 that all living animals and plants " are the lineal 

 descendants of those which lived long before the 

 Silurian epoch." 1 



It is an obvious consequence of this theory of 

 descent with modification, as it is sometimes called, 

 that all plants and animals, however different they 

 may now be, must, at one time or other, have been 

 connected by direct or indirect intermediate grada- 

 tions, and that the appearance of isolation presented 

 by various groups of organic beings must be unreal. 



No part of Mr. Darwin's work ran more directly 

 counter to the prepossessions of naturalists twenty 

 years ago than this. And such prepossessions were 

 very excusable, for there was undoubtedly a great 

 deal to be said, at that time, in favour of the fixity 

 of species and of the existence of great breaks, 

 which there was no obvious or probable means of 

 filling up, between various groups of organic beings. 



For various reasons, scientific and unscientific, 

 much had been made of the hiatus between man 

 and the rest of the higher mammalia, and it is no 

 wonder that issue was first joined on this part of 

 the controversy. I have no wish to revive past 

 and happily forgotten controversies ; but I must 

 state the simple fact that the distinctions in the 

 cerebral and other characters, which were so hotly 

 affirmed to separate man from all other animals in 

 1860, have all been demonstrated to be non- 

 1 Origin of Species, p. 458. 



