LECTURE XIV. 409 



consider the mode in wMcli man proceeds in the production of 

 any race. He finds some animal wliich appears to him to 

 possess some useful qualities ; lie couples this with another 

 animal of the opposite sex possessing nearly identical qua- 

 lities. The breed thus obtained is fed and nurtured in such 

 a manner as to improve^ if possible^ the desired charac- 

 ters. In the second generation he again selects animals 

 possessing the desired qualities in the highest degree ; he 

 pairs them with each other^ or with the parent stock, or, in 

 later generations, with the preceding generations, until he has 

 attained his object. Is the process different in nature ? It 

 is certainly, in so far as the same starting point is given 

 hundreds, perhaps thousands, of times without further develop- 

 ment, because the selection in breeding can be easily efiected 

 by the interference of man. But as qualities which prove 

 advantageous to the individual in the struggle for existence 

 also endow it with superior generative powers, this superiority 

 will produce the same result in nature, though at a slower 

 rate than when efiected by man by exclusive selection. Thus, 

 with regard only to the higher mammals, it is well known that 

 there is scarcely any species in which there does not exist a 

 kind of courting, leading frequently to fierce combats between 

 a number of males for a certain female, after which the con- 

 queror carries home his bride. Upon this fact rests probably 

 the continuance of the species in the highest development of 

 which it is capable. But since every individual better endowed 

 for the struggle for existence, will transmit his superior qual- 

 ities, it follows that his offspring will gradually attain an 

 ascendancy, and displace the less privileged individuals, until 

 finally it becomes the sole representative of the race. Thus 

 the same efi"ects which man, by his intelligence, produces in the 

 shortest time, namely, by the application of the most favourable, 

 and the exclusion of noxious influences, are equally produced by 

 nature, the length of time suppljang, to a certain extent, the 

 place of human intelligence. Just as in the chemical trans- 

 formations which take place in the bowels of the earth, length of 

 time is the mysterious factor, so is it the agent in the production 

 of organic forms, which, by apparently insignificant changes, is 



