428 THE METHOD OF ORFANIC EVOLUTION. 



Although Mr. Galtou begins by the consideration of races only, that 

 is, of Avell-uiarked forms below the value of species, yet later on he 

 api)lies liis tlieory to the evolution of species and of all higher groups. 

 Speaking of discontinuous or, as he terms it, transilient variation, he 

 says: "A ]ea]> has taken place into a new position of stabiltiy. I am 

 unable to conceive the i)ossibility of evolutionary progress except by 

 transiliences, for, if they were mere divergences, each subsequent gen- 

 eration would teiul to regress backward toward the typical center, and 

 tlie advance which has been made would be temporary and could not be 

 maintained" (1. c, p. 368.) Mr. (xalton has before implicitly admitted 

 that there is sucli a thing as natural selection, yet in this passage he 

 reasons as if it liad no existence, and that regression to mediocrity 

 would occur Just the same with it as without it. For the essence of 

 natural selection isthatit in'cserves and thus increases favorable varia- 

 tions by destroying the unfavorable; but this statement by no means 

 expresses the real power of selection, which may be better illustrated 

 by saying that it destroys abont 99 i^er cent of the bad and less bene- 

 ficial variations and iireserves about the 1 per cent of those which are 

 extremely favorable. With such an amount of selection how can there 

 be any possible " regression backward toward the typical center" when 

 any change in the environment demands an advance in some special 

 direction beyond it as the only means of preserving the race from 

 extinction f Well did Darwin say that unless the universal struggle 

 for existence "be thoroughly ingrained in the mind, the whole economy 

 of nature, with every fact on distribution, rarity, abundance, extinc- 

 tion, and variation will be <limly seen or quite misunderstood." Almost 

 all the misconceptions of popular writers against Darwiinsm arise from 

 the want of this constantly present recollection ; and as capable and 

 instructed writers, such as Mr. Galton and Mr. Bateson, as well as 

 capable, but nninstructed writers, such as Lord Salisbury, alike suffer 

 in this respect, it is needfnl to again state obvious facts which may 

 serve to drive home the overwhelming importance of this factor in 

 evolution. 



Let us suppose an animal which lives ten years and produces 10 young 

 (5 j)airs) each year, a moderate allowance even for many mammals and 

 birds. A little simple arithmetic will show that if none died for five 

 years there would be (>,4:80 pairs in place of the 1 pair, or (»,480,000,000 

 in place of 1,0(10,000, as the case might be. But it is evident that 

 such an average rate of increase for all animals could not go on for even 

 one or two years, as no country could suj)ply them with- food. We will 

 suppose, then, that only 1 pair, instead of 5, survive each year to breed 

 the next year; but if this goes on for the ten years of the life of the 

 first pair we shall still have 512 pairs instead of each pair, a number 

 which is ecpially impossible. Let us, then, suppose that only one-fiftieth 

 part of those born survive, that is, that only 1 individual lives to 

 breed out of 5 successive broods of 10 each; even then, at the end 



