WALLACE'S ESSAY. 75 



longer than the parent species, while the scale on 

 which nature works is so vast that an average 

 tendency must in the end attain its full result. 



Comparing domestic with wild animals, the very 

 existence of the latter depends upon their senses and 

 physical powers. Not so with the former, which are 

 defended and fed by man. 



Any favourable variety of a domestic animal is 

 utterly useless to itself; while any increase of the 

 powers and faculties of wild animals is immediately 

 available, creating, as it were, a new and superior 

 animal. 



Again, with domestic animals all variations have 

 an equal chance, and those which would be extremely 

 injurious in a wild state are, under the artificial 

 conditions, no disadvantage. Our domestic breeds 

 could never have come into existence in a wild state, 

 and if turned wild " must return to something near 

 the type of the original wild stock, or become 

 altogether extinct"* 



Hence we cannot argue from domestic to wild 

 animals, the conditions of life in the two being 

 completely opposed. 



Lamarck's hypothesis of change produced by the 

 attempts of animals to increase the development of 



* Wallace has added the following note to the reprint in "Natural 

 Selection and Tropical Nature," London, 1891, p. 31: "That is, 

 they will vary, and the variations which tend to adapt them to the 

 wild state, and therefore approximate them to wild animals, will he 

 preserved. Those individuals which do not vary sufficiently will 

 perish," 



