Ii8 Darwin and Ronianes dealt with. 



XIV. 



If slight change of external conditions could have 

 such effects as Mr. Darwin has described in chap, xii, 

 Domestication, in the case of the Aylesbury Ducks, 

 which in a different part of England lost their habit 

 of early laying, to lay exactly at the same time as the 

 common ducks do there, does this not suggest that 

 more weight should be laid on possible changes in 

 external conditions in wild birds and other wild crea- 

 tures, and certain possibiHties of birds of different 

 families, if not of different species, under similar 

 conditions, coming to act similarly even under very 

 unexpected lines ? 



Mr. Darwin's own argument, at p. 43, vol. ii, of 

 Domestication, surely in full force applies here. He 

 says : 



" There are some breeds of fowls which are called 

 * Everlasting layers,' because they have lost the 

 instinct of incubation ; and so rare is it for them to 

 incubate that I have seen notices published in works 

 on poultry, when hens of such breeds have taken to 

 sit. Yet the aboriginal species was, of course, a good 

 incubator ; for with birds in a state of nature hardly 

 any instinct is so strong as this ... I raised several 

 chickens from a PoHsh hen by a Spanish cock — 

 breeds which do not incubate — and none of the young 

 hens at first recovered their instinct, and this 

 appeared to afford a well-marked exception to the 

 foregoing rule ; but one of these hens, the only one 

 which was preserved, in the third year sat well on her 

 eggs and reared a brood of chickens. So that here 



