328 LAWS OF VARIATION. Chap. XXV. 



vertebra?, with strengthened ligaments; enlarged dorsal 

 vertebras to support the neck, with powerful fore-legs and 

 feet; all these parts being supplied with proper muscles, 

 blood-vessels, and nerves. How then could these admirably 

 co-ordinated modifications of structure have been acquired? 

 According to the doctrine which I maintain, the horns of the 

 male elk were slowly gained through sexual selection, — that 

 is, by the best-armed males conquering the worse-armed, and 

 leaving a greater number of descendants. But it is not at all 

 necessary that the several parts of the body should have 

 simultaneously varied. Each stag presents individual charac- 

 teristics, and in the same district those which had slightly 

 heavier horns, or stronger necks, or stronger bodies, or were 

 the most courageous, would secure the greater number of 

 does, and consequently have a greater number of offspring. 

 The offspring would inherit, in a greater or less degree, these 

 same qualities, would occasionally intercross with one another, 

 or with other individuals varying in some favourable manner ; 

 and of their offspring, those which were the best endowed in 

 any respect would continue multiplying ; and so onwards, 

 always progressing, sometimes in one direction, and some- 

 times in another, towards the excellently co-ordinated struc- 

 ture of the male elk. To make this clear, let us reflect on 

 the probable steps, as shown in the twentieth chapter, by 

 which our race and dray horses have arrived at their present 

 state of excellence ; if we could view the whole series of 

 intermediate forms between one of these animals and an early 

 unimproved progenitor, we should behold a vast number of 

 animals, not equally improved in each generation throughout 

 their entire structure, but sometimes a little more in one 

 point, and sometimes in another, yet on the whole gradually 

 approaching in character to our present race or dray horses, 

 which are so admirably fitted in the one case for fleetness and 

 in the other for draught. 



Although natural selection would thus 37 tend to give to 



37 Mr. Herbert Spencer (' Principles " faculties multiply, and as fast as 



of Biolooy,' 1864, vol. i. pp. 452, " the number of organs that co- 



468) takes a different view; and in one "operate in anv given .function 



place remarks : " We have seen reason " increases, indirect equilibration 



" to think that, as fast as essential " through natural selection becomes 



