vr “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.” 
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 SE eae 
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 jommed 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. 
