264 JJarwiJt, and after Darwin. 



to survive, and so to perpetuate the improvement in 

 his or her progeny. 



Now I say that all these several component parts 

 of Darwinian doctrine are not matters of theory, but 

 matters of fact. The only element of theory in his 

 doctrine of evolution by natural selection has reference 

 to the degree in which these observable facts, when 

 thus brought together, are adequate to account for the 

 process of evolution. 



So much, then, as a statement of the theory of 

 natural selection. But from this statement — i. e. from 

 the theory of natural selection itself — there follow 

 certain matters of general principle which it is im- 

 portant to bear in mind. These, therefore, I shall 

 here proceed to mention. 



First of all, it is evident that the theory is applicable 

 as an explanation of organic changes in specific types 

 only in so far as these changes are of use, or so far 

 as such changes endow the species with better chances 

 of success in the general struggle for existence. This 

 is the only sense in which I shall always employ the 

 terms use, utility, service, benefit, and so forth — that 

 is to say, in the sense of life-preserving. 



Next, it must be clearly understood that the life 

 which it is the object so to speak, of natural selection 

 to preserve, is primarily the life of the species ; not 

 that of the individual. Natural selection preserves 

 the life of the individual only in so far as this is 

 conducive to that of the species. Wherever the life- 

 interests of the individual clash with those of the 

 species, that individual is sacrificed in favour of others 



