152 EVOLUTION 



dividuals. Common species that range wide 

 and are much diffused are those which vary 

 most. The species of the larger genera in 

 each country vary more frequently than the 

 species of the smaller genera. The species 

 of large genera present strong analogies with 

 varieties, which suggests that they originated 

 as such. 



STRUGGLE FOR EXISTENCE. The term 

 44 struggle for existence " is used in a large 

 and metaphorical sense, including dependence 

 of one being upon another, and embracing 

 (which is more important) not only the life 

 of the individual, but success in leaving 

 progeny. From the high (geometric*!) rate 

 of increase of all organic beings (even the 

 slow breeders requiring only a few more years 

 to people a whole district) struggle inevitably 

 follows, either one individual with another of 

 the same species, or with the individuals of 

 a distinct species, or with the physical con- 

 ditions of life. It is the doctrine of Malthus 

 applied with manifold force to the entire 

 animal and vegetable kingdoms, for in this 

 case there can be no artificial increase of food 

 and no prudential restraints from marriage. 



The checks to increase are very obscure. 

 Eggs or young animals generally suffer most, 

 and plants, mostly as seedlings, both from 



