MIRACLES OF SCIENCE 



This process of the weeding out of the unfit, 

 through survival and dominance of the relatively fit, 

 Darwin spoke of as natural selection. The doctrine 

 presupposes that individuals of a species do vary 

 from one another, but Darwin made no attempt to 

 explain such varieties. He recognized of course that 

 all variations must be due to the operation of natural 

 laws; but he recognized also that we are at present 

 in ignorance as to the exact character of these laws. 

 So he confessedly begged the question by speaking 

 of the divergence between different mmbers of the 

 same species as constituting "spontaneous" variation. 



That such variations occur is matter of every-day 

 observation. In point of fact no two individuals of 

 any species are absolutely identical, so that varia- 

 tion may be said to be the undeviating rule rather 

 than the exception. As any given variation must, 

 obviously, be in some degree either favorable or un- 

 favorable to the individual, it would appear as if the 

 materials for the operation of natural selection are 

 ever present, and as if each species might be sup- 

 posed to be in a state of slow but constant fluctua- 

 tion. The accumulation of slight variations, passed 

 on from one generation to another, was supposed 

 to account, granted time enough, for the develop- 

 ment of the divergent forms of life that are observed 

 to people the world, from the single-celled pro- 

 tozoon to man. 



THE NEW THEORY OF MUTATION 



Let it be said once for all that this Darwinian idea 

 of the origin of species through natural selection, 



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