CnAi-. IV. NATURAL SELECTION. 87 



habits of one si)ecics would often give it an advantugc over 

 others ; and still further modifications of the same liind Avould 

 often still further increase the advantage, as long as the species 

 continued under the same conditions of life and profited by 

 similar means of sul)sistence and defence. No country can be 

 named, in which all the native inhabitants are now so perfectly 

 adapted to each other and to the physical conditions under 

 which they live, that none of them could be still better adapted 

 or improved ; for, in all countries, the natives have been so far 

 conquered by naturalized productions, tliat they have allowed 

 foreigners to take iirin ])ossession of the land. And, as for- 

 eigners have thus in every country beaten some of the natives, 

 Ave may safely conclude that the natives might have been mod- 

 ified with advantage, so as to have better resisted the in- 

 truders. 



As man can produce and certainly has produced a great 

 result by his methodical and unconscious means of selection, 

 what may not natural selection effect ? Man can act only on 

 external and visible characters : Nature, if I may be allowed 

 to j)ersonify the natural preservation or survival of the fittest, 

 cares nothing for appearances, except in so far as they are use- 

 ful to any being. She can act on every internal organ, on 

 every shade of constitutional difference, on the whole machinery 

 of life. Man selects only for his own good ; Nature only for 

 that of the being which she tends. Every selected character is 

 fully exercised by her, as is implied by the fact of their selection. 

 Man keeps the natives of many climates in the same country ; 

 he seldom exercises each selected character in some peculiac 

 and fitting manner ; he feeds a long and a short beaked pigeon 

 on the same food ; he does not exercise a long-backed or long- 

 legged quadrup(^(l in any peculiar manner ; he exposes sheep 

 with long and short wool to the same climate. lie does not 

 allow the most vigorous males to struggle for the females. He 

 does not rigidly destroy all inferior animals, but protects during 

 each varying season, as far as lies in his power, all his produc- 

 tions. He often begins his selection by some half-monstrous 

 form; or at least by some modification prominent enough to 

 catch the eye or to be plainly useful to him. Under Nature, 

 the slightest differences of structure or constitution may well 

 turn the nicely-balanceil scale in the struggle for life, and so be 

 preserved. How fleet uig are the wishes and eflbrts of man! 

 how short his time ! and consequently how poor will be his 

 results, comjiared with those accumulated l)y Nature during 



