Chap. III. STRUGGLE FOR EXISTENCE. 61 



f o the hairs of a quadruped or feathers of a bird ; in the 

 structure of the beetle which dives through the water ; 

 in the plumed seed which is wafted by the gentlest 

 breeze ; in short, we see beautiful adaptations every- 

 where and in every part of the organic world. 



Again, it may be asked, how is it that varieties, which 

 I have called incipient species, become ultimately con- 

 verted into good and distinct species, winch in most 

 cases obviously differ from each other far more than do 

 the varieties of the same species? How do those groups 

 of species, which constitute what are called distinct 

 genera, and which differ from each other more than do 

 the species of the same genus, arise ? All these results, 

 as we shall more fully see in the next chapter, follow 

 inevitably from the struggle for life. Owing to this 

 struggle for life, any variation, however slight and from 

 whatever cause proceeding, if it be in any degree pro- 

 fitable to an individual of any species, in its infinitely 

 complex relations to other organic beings and to ex- 

 ternal nature, will tend to the preservation of that indi- 

 vidual, and will generally be inherited by its offspring. 

 The offspring, also, will thus have a better chance of 

 surviving, for, of the many individuals of any species 

 which are periodically born, but a small number can 

 survive. I have called this principle, by which each 

 slight variation, if useful, is preserved, by the term of 

 Natural Selection, in order to mark its relation to man's 

 power of selection. We have seen that man by selec- 

 tion can certainly produce great results, and can adapt 

 organic beings to his own uses, through the accumula- 

 tion of slight but useful variations, given to him by the 

 hand of Nature. But Natural Selection, as we shall 

 hereafter see, is a power incessantly ready for action, 

 and is as immeasurably superior to man's feeble efforts, 

 as the works of Nature are to those of Art. 



