Chap. L] VARIATION UNDER DOMESTICATION. 17 



state. In many cases we do no know what the abo- 

 riginal stock was, and so conld not tell whether or not 

 nearly perfect reversion had ensued. It would be 

 necessary, in order to prevent the effects of inter- 

 crossing, that only a single variety should have been 

 turned loose in its new home. Nevertheless, as our 

 varieties certainly do occasionally revert in some of their 

 characters to ancestral forms, it seems to me not 

 improbable that if we could succeed in naturalising, or 

 were to cultivate, during many generations, the several 

 races, for instance, of the cabbage, in very poor soil (in 

 which case, however, some effect would have to be 

 attributed to the definite action of the poor soil), that 

 they would, to a large extent, or even wholly, revert 

 to the wild aboriginal stock. Whether or not the 

 experiment would succeed, is not of great importance 

 for our line of argument: ; for by the experiment itself 

 the conditions of life are changed. If it could be shown 

 that our domestic varieties manifested a strong tendency 

 to reversion, — that is, to lose their acquired characters, 

 whilst kept under the same conditions, and whilst kept 

 in a considerable body, so that free intercrossing might 

 check, by blending together, any slight deviations in 

 their structure, in such case, I grant that we could de- 

 duce nothing from domestic varieties in regard to 

 species. But there is not a shadow of evidence in 

 favour of this view : to assert that we could not breed 

 our cart and race-horses, long and short-horned 

 cattle, and poultry of various breeds, and esculent 

 vegetables, for an unlimited number of generations, 

 would be opposed to all experience. 



