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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