The Making of Species 



fitable to itself, under the complex and some- 

 times varying conditions of life, will have a 

 better chance of surviving, and thus be naturally 

 selected. From the strong principle of inherit- 

 ance, any selected variety will tend to propagate 

 its new and modified form." 



In other words, the struggle for existence 

 amongst all organic beings throughout the world, 

 which inevitably follows from the high geometri- 

 cal ratio of their increase, results in the survival 

 of the fittest, that is to say, of those best adapted 

 to cope with their enemies and to secure their 

 food. Since organisms are thus naturally selected 

 in nature, we may speak of a natural selection 

 which acts in much the same way as the human 

 breeder does. Darwin's theory, then, is that all 

 the variety of organisms which now exist have 

 been evolved from one or more forms by this 

 process of natural selection. 



The objections which have been urged against 

 the theory of natural selection fall into two 

 classes. 



I. Those which strike at its root, which either 

 deny that there is any natural selection, or 

 declare that it is not capable of producing a 

 new species. 



II. Those which are directed against the all- 

 sufficiency of natural selection to account for 

 organic evolution. 



Those of the first class need not detain us 



32 



