The Making of Species 
which afforded a plausible explanation of what 
they believed to have occurred. 
Hence the rapturous welcome accorded to the 
theory of natural selection by the more pro- 
gressive biologists. 
Another point in Darwin’s favour was the 
delightful simplicity of his hypothesis. Nothing 
could be more enticingly probable. It is based 
on the unassailable facts of variation, heredity, 
and the tendency of animals to multiply in 
numbers. Everybody knows that the breeder 
can fix varieties by careful breeding. Darwin 
had simply to show that there is in nature some- 
thing to take the part played among domesticated 
animals by the human breeder. This he was 
able to do. As the numbers of species remain 
stationary, it is evident that only a small portion 
of the animals that are born can reach maturity. 
A child can see that the individuals most likely 
to survive are those best adapted to the circum- 
stances of their life. Even as the breeder weeds 
out of his stock the creatures not suited to his 
purpose, so in nature do the unfit perish in the 
everlasting struggle for existence. 
In nature there is a selection corresponding to 
that of the breeder. 
It is useless to deny the existence of this selec- 
tion in nature, this natural selection. The only 
disputable point is whether such selection can 
do all that Darwin demanded of it. 
4 
