Chap. VIIJ THEORY OF NATURAL SELECTION. 277 



perish, if not fed by their owners. Before coming to 

 Mr. Mivart's objections, it may be well to explain once 

 again how natural selection will act in all ordinary cases. 

 Man has modified some of his animals, without neces- 

 sarily having attended to special points of structure, 

 by simply preserving and breeding from the fleetest in- 

 dividuals, as with the race-horse and greyhound, or as 

 with the game-cock, by breeding from the victorious 

 birds. So under nature with the nascent girafEe, the in- 

 dividuals which were the highest browsers, and were 

 able during dearths to reach even an inch or two above 

 the others, will often have been preserved; for they will 

 have roamed over the whole country in search of food. 

 That the individuals of the same species often differ 

 slightly in the relative lengths of all their parts may be 

 seen in many works of natural history, in which careful 

 measurements are given. These slight proportional dif- 

 ferences, due to the laws of growth and variation, are 

 not of the slightest use or importance to most species. 

 But it will have been otherwise with the nascent giraffe, 

 considering its probable habits of life; for those indi- 

 viduals which had some one part or several parts of 

 their bodies rather more elongated than usual, would 

 generally have survived. These will have intercrossed 

 and left offspring, either inheriting the same bodily pe- 

 culiarities, or with a tendency to vary again in the same 

 manner; whilst the individuals, less favoured in ihe 

 same respects, will have been the most liable to perish. 



We here see that there is no need to separate single 

 pairs, as man does, when he methodically improves a 

 breed: natural selection will preserve and thus separate 

 all the superior individuals, allowing them freely to in- 

 tercross, and will destroy all the inferior individuals. 



