The Making of Species 
can at most effect, not the origin of species, but 
the survival of certain species which have arisen 
as the result of some other force. Its position 
is changed ; it is no longer a cause of the origin 
of new organisms, but a sieve determining 
which of certain ready-made forms shall survive. 
Evidently, then, we shall not be able to fully 
understand the evolutionary process until we 
have discovered how it is that variations are 
caused. In other words, we must go considerably 
farther than Darwin attempted to do. 
Before proceeding to inquire into the true 
nature of variations, it behoves us to set forth 
briefly the ideas of Darwin on the subject. We 
shall then be in a position to see how much 
progress has been made since the days of that 
great biologist. 
It is not at all easy to discover exactly what 
were Darwin’s views on the subject of variation. 
A perusal of his works reveals contradictions, 
and gives one the impression that he himself 
scarcely knew his own mind upon the subject. 
This should not be a matter for surprise. 
We must remember that Darwin had to do 
pioneer work, that he had to deal with alto- 
gether new conceptions. Such being the case, 
his ideas were of necessity somewhat hazy ; they 
underwent considerable modification as fresh 
facts came to his knowledge. 
Towards the end of his life Darwin recognised 
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