CIRCUMSTANCES FAVOURABLE TO SELECTION 55 



picked out the best secdlin.^-s and bred from them, then (with 

 some aid by crossing distinct species) those many admirable 

 varieties of the strawberry were raised which have appeared 

 during the last half-century. 



With animals, facility in preventing crosses is an important 

 element in the formation of new races, — at least, in a country 

 which is already stocked with other races. In this respect 

 enclosure of the land plays a part. Wandering savages or 

 the inhabitants of open plains rarely possess more than one 

 breed of the same species. Pigeons can be mated for life, and 

 this is a great convenience to the fancier, for thus many races 

 may be improved and kept true, though mingled in the same 

 aviary ; and this circumstance must have largely favoured the 

 formation of new breeds. Pigeons, I may add, can be propa- 

 gated in great numbers and at a very quick rate, and inferior 

 birds may be freely rejected, as when killed they serve for 

 food. On the other hand, cats, from their nocturnal rambling 

 habits, cannot be easily matched, and, although so much 

 valued by women and children, we rarely see a distinct breed 

 long kept up ; such breeds as we do sometimes see are 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 surprisingly 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 dis- 

 play of distinct breeds ; but the goose, under the conditions to 

 which it is exposed when domesticated, seems to have a sin- 

 gularly inflexible organisation, though it has varied to a 

 slight extent, as I have elsewhere 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 as- 



