48 CIRCUMSTANCES FAVOURABLE. [Chap. L 



almost always imported from some other country. 

 Although I do not doubt that some domestic animals 

 vary less than others, yet the rarity or absence of 

 distinct breeds of the cat, the donkey, peacock, goose, 

 &c., may be attributed in main part to selection not 

 having been brought into play: in cats, from the 

 difficulty in pairing them; in donkeys, from only a few 

 being kept by poor people, and little attention paid to 

 their breeding; for recently in certain parts of Spain 

 and of the United States this animal has been sur- 

 prisingly modified and improved by careful selection: 

 in peacocks, from not being very easily reared and a 

 large stock not kept: in geese, from being valuable 

 only for two purposes, food and feathers, and more 

 especially from no pleasure having been felt in the 

 display of distinct breeds; but the goose, under the 

 conditions to which it is exposed when domesticated, 

 seems to have a singularly inflexible organisation, 

 though it has varied to a slight extent, as I have else- 

 where described. 



Some authors have maintained that the amount of 

 variation in our domestic productions is soon reached, 

 and can never afterwards be exceeded. It would be 

 somewhat rash to assert that the limit has been attained 

 in any one case; for almost all our animals and plants 

 have been greatly improved in many ways within a 

 recent period; and this implies variation. It would be 

 equally rash to assert that characters now increased to 

 their utmost limit, could not, after remaining fixed for 

 many centuries, again vary under new conditions of 

 life. Ko doubt, as Mr. Wallace, has remarked with 

 much truth, a limit will be at last reached. For in- 

 stance, there must be a limit to the fleetness of any 



