38 ON THE ORIGIN OF SPECIES 



belong 1 to poor people, and are mostly in small lots t 

 they never can be improved.' On the other hand, 

 nurserymen, from raising large stocks of the same 

 plants, are generally far more successful than amateurs 

 in getting new and valuable varieties. The keeping of 

 a large number of individuals of a species in any 

 country requires that the species should be placed 

 under favourable conditions of life, so as to breed freely 

 in that country. When the individuals of any species 

 are scanty, all the individuals, whatever their quality 

 may be, will generally be allowed to breed, and this 

 will effectually prevent selection. But probably the 

 most important point of all is, that the animal or 

 plant should be so highly useful to man, or so much 

 valued by him, that the closest attention should be paid 

 to even the slightest deviation in the qualities or 

 structure of each individual. Unless such attention be 

 paid nothing can be effected. I have seen it gravely 

 remarked, that it was most fortunate that the straw- 

 berry began to vary just when gardeners began to 

 attend closely to this plant. No doubt the strawberry 

 had always varied since it was cultivated, but the slight 

 varieties had been neglected. As soon, however, as 

 gardeners picked out individual plants with slightly 

 larger, earlier, or better fruit, and raised seedlings 

 from them, and again picked out the best seedlings and 

 bred from them, then, there appeared (aided by some 

 crossing with distinct species) those many admirable 

 varieties of the strawberry which have been raised 

 during the last thirty or forty years. 



In the case of animals with separate sexes, facility in 

 preventing crosses is an important element of success 

 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 kept true, though 

 mingled in the same aviary ; and this circumstance 



