222 SELECTION. Chap. XXL 



or biennials, wliicli therefore are capable of rapid propagation, 

 and thus of improvement. Sea-kale, asparagus, common and 

 Jerusalem artichokes, potatoes, and onions, must be excepted, 

 as they are perennials : but onions are propagated like annuals, 

 and of the other plants just specified, none, with the exception 

 of the potato, have yielded in this country more than one or 

 two varieties. In the Mediterranean region, where artichokes 

 are often raised from seed, there are several kinds, as I hear 

 from Mr. Bentham. No doubt fruit-trees, which cannot be 

 propagated quickly by seed, have yielded a host of varieties, 

 though not permanent races ; but these, judging from pre- 

 historic remains, have been produced at a comparatively late 

 period. 



A species may be highly variable, but distinct races will 

 not be formed, if from any cause selection be not applied. It 

 would be difficult to select slight variations in fishes from 

 their place of habitation ; and though the carp is extremely 

 variable and is much attended to in Germany, only one well- 

 marked race has been formed, as I hear from Lord A. Russell, 

 namely the sjpiegel-carpe ; and this is carefully secluded from 

 the common scaly kind. On the other hand, a closely allied 

 species, the gold-fish, from being reared in small vessels, and 

 from having been carefully attended to by the Chinese, has 

 yielded many races. Neither the bee, which has been semi- 

 domesticated from an extremely remote period, nor the cochi- 

 neal insect, which was cultivated by the aboriginal Mexicans,*^ 

 has yielded races ; and it would be impossible to match the 

 queen-bee with any particular drone, and most difficult to 

 match cochineal insects. Silk-moths, on the other hand, have 

 been subjected to rigorous selection, and have produced a host 

 of races. Cats, which from their nocturnal habits cannot be 

 selected for breeding, do not, as formerly remarked, yield dis- 

 tinct races within the same country. Dogs are held in 

 abomination in the East, and their breeding is neglected ; 

 consequently, as Prof. Moritz "Wagner ^^ reuiarks, one kind 

 alone exists there. The ass in England varies much in 



** Isidore Geoffroy Saint-Hilaire, *^ ' Die Darwin'sche Theorie und das 



* Hist. Nat. Gen.,' torn. iii. p. 49. ' On Migrationsgesetz der Organismen,' 

 the Cochineal Insect,' p. 46. 1868, p. 19. 



