(■ 



>v.. 



'%t 



r 



UI 



en 



^w 



;\ 



«* 



^c. 





^ ^ 



H 



^ 4 



e 



ClSf 



w. 



tv 



or 



^^A 



'nre- 

 1'Od 



COT+ft 



Ihow 



r- 



« ■ 



imi 



Wu 



J 



4 



to 



in? to 

 ffsfor 



form 



^. i; 





i< 



lit 





Ch. XXXV.] AND DAEWIN ON NATUEAL SELECTION. 



279 



must occur in nature under clianged conditions in the ani- 

 mate and inanimate world. Reference was made in the 

 same letter to the law of human population first enunciated 



Malthus, or the tendency in man 



made 



o-ment m the same r 

 conntries the liumaii 



We 



111 



^ F ^^ 



five years^ and would have multiplied faster if food could 

 have been supplied. In li 



manner 



is capable of increasing 



so rapidly^ that if it were un- 

 checked bj other species^ it would soon occupy the greater 

 part of the habitable globe ; but in the general struggle for 

 life fcAV only of those which are born into the world can 

 obtain subsistence and arrive at maturity. In any 



given 



survive 



others, and this is often determined by a slight peculiarity 

 capable in a severe competition of turning the scale in their 



ISTotwithstandinp- the resemblance 



s 



same 



two of them are exactly alike. The breeder chooses out 

 from among the varieties presented to him those best suited 

 to his purpose, and the divergence from the original stock 



) increased by breeding in each succes- 



is more 

 sive ^ei 



mor 



om 



most marked desf 



In this manner Mr. 



Darwin suggests that as the surrounding conditions in the ■ 

 organic and inorganic world slowly alter in the course of 



mor 



geological periods, new races which 



with the altered state of things must be formed in a state o^i 



nature, and must often supplant the parent type. 



Although this law of natural selection constituted one only 

 of the grounds on which Mr. Darwin relied for estahlishino 

 his views as to the 



formed so original 

 the fact of Mr. Wa 



origin 



of species by variation, yet it 

 and prominent a part of his theory that 



same principle and illustrated it by singularly analogous ex- 

 amples, is remarkable. It raises at the same time a strong 

 presumption in favour of the truth of the doctrine. Both 

 writers referred to the num.ber of the feathered tribe which 



