62 Struggle for Life. 



tilized only by the humble-bee, and bumble-bees 

 flourish only where mice do not destroy their 

 combs and nests, and mice are destroyed by cats, 

 we can see that without cats there would be no 

 combs and nests, no bees, and therefore no fertili 

 zation of clover. 



Directly or indirectly, then, the animal and 

 vegetable kingdoms are, owing to the enormous 

 rate at which living beings tend to increase, the 

 scene of universal competition and struggle for 

 existence, in which the great majority must inev 

 itably perish. We have seen, however, -that all 

 living beings are subject to slight modifications; 

 and taking account of the infinite complexity of 

 the relations of all organic beings to one another, 

 and to their conditions of life, it would be strange 

 if some of these modifications were not more ben 

 eficial than others. In that case the individuals 

 that have happened to undergo this profitable va 

 riation would have an advantage over their rivals. 

 They would, accordingly, be victorious in the 

 struggle for life ; and transmitting their benefi 

 cial peculiarities to descendants, these would enjoy 

 a similar advantage. Such favored forms would 

 spread and conquer, while their rivals would 

 first decline and then become utterly extinct. 

 This is what Darwin means by natural selection, 



