124 THE WRITING OF THE 'ORIGIN OF SPECIES.' [1858. 



enough for selection to act on. Some of its inhabitants will 

 be exterminated, and the remainder will be exposed to the 

 mutual action of a different set of inhabitants, which I believe 

 to be more important to the life of each being than mere 

 climate. Considering the infinitely various ways beings have 

 to obtain food by struggling with other beings, to escape 

 danger at various times of life, to have their eggs or seeds 

 disseminated, &c. &c., I cannot doubt that during millions of 

 generations individuals of a species will be born with some 

 slight variation profitable to some part of its economy ; such 

 will have a better chance of surviving, propagating this varia- 

 tion, which again will be slowly increased by the accumulative 

 action of natural selection ; and the variety thus formed will 

 either coexist with, or more commonly will exterminate its 

 parent form. An organic being like the woodpecker, or 

 the mistletoe, may thus come to be adapted to a score of 

 contingencies ; natural selection, accumulating those slight 

 variations in all parts of its structure which are in any way 

 useful to it, during any part of its life. 



V. Multiform difficulties will occur to every one on this 

 theory. Most can, I think, be satisfactorily answered. 



" Natura non facjt saltum " answer some of the most obvi 

 ous. The slowness of the change, and only a very few unde 

 going change at any one time answers others. The extreme 

 imperfections of our geological records answer others. 



VI. One other principle, which may be called the principle 

 of divergence, plays, I believe, an important part in the origin 

 of species. The same spot will support more life if occupied 

 by very diverse forms : we see this in the many generic forms 

 in a square yard of turf (I have counted twenty species 

 belonging to eighteen genera), or in the plants and insects, 

 on any little uniform islet, belonging to almost as many 

 genera and families as to species. We can understand this 

 with the higher animals, whose habits we best understand. 

 We know that it has been experimentally shown that a plot 



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