76 STRUIgLB foe existence. [Chap. IIL 



ditions of life, and ^i one organic being to another 

 being, been perfected;' We see these beautiful co-adap- 

 tations most plainly in the woodpecker and the mistle- 

 toe; and only a littlf/less plainly in the humblest para- 

 site which clings to 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 j)ea utiful ada p- 

 tations everywhere 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 

 converted into good and distinct species which in most 

 eases 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 from the struggle for life. \ Owing to 

 this struggle, variations, however sligh t and from 

 whatever cause proceeding, if they be in any degre e 

 profitab le to the individuals of a species, in their in- 

 finitely complex relations to other organic beings and 

 to their physical conditions of life, will tend to the 

 pres ervation of such individuals , and will generally be 

 inhe rited by the offsp ring. 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 Natural^Selection^n order to 

 mark its relation to man's power of selection.'. But the 



