210 MISCELLANEOUS OBJECTIONS TO TEE 



or hoofed animals inhabiting the same country; and this 

 must be a great advantage to it during dearths. The Niata 

 cattle in South America show us how small a difference in 

 structure may make, during such periods, a great differ- 

 ence in preserving an animal's life. These cattle can browse 

 as well as others on grass, but from the projection of the 

 lower jaw they cannot, during the often recurrent droughts, 

 browse on the twigs of trees, reeds, etc., to which food the 

 common cattle and horses are then driven; so that at 

 these times the Niatas perish, if not fed by their 

 owners. Before coming to Mr. Mivart's objections, 

 it may be well to exjilain once again how natural 

 selection will act in all ordinary cases. Man has 

 modified some of his animals, without necessarily having 

 attended to special points of structure, by simply pre- 

 serving and breeding from the fleetest individuals, as with 

 the race-horse and greyhound, or as with the game-cock, 

 by breeding from the victorious birds. So undennature with 

 the nascent giraffe, the individuals which were the highest 

 browsers and were able during dearths to reach even an 

 inch or two above the others, will often have been pre- 

 served; 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 

 differences, 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, con- 

 sidering its probable habits of life; for those individuals 

 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 peculiarities, or with a 

 tendency to vary again in the same manner ; while the 

 individuals less favored in the 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: natu- 

 ral selection will preserve and thus separate all the superior 

 individuals, allowing them freely to intercross, and will 

 destroy all the inferior individuals. By this process long- 



