One General Law. 119 



we have the appearance with advancing age of a 

 primitive instinct in the same manner as we have seen 

 that the red plumage of the Gallus hankiva is some- 

 times re-acquired by crossed and purely bred fowls of 

 various kinds as they grow old." 



Here Mr. Darwin speaks of certain breeds of hens 

 recovering their instinct for brooding : if they re- 

 covered an instinct which they had lost, is it logical or 

 legitimate to speak of them as acting on an instinct by 

 persistent laying ? If the one was in the true sense an 

 instinct which was, as he says, recovered, then the 

 other practice was not due to instinct, but to some- 

 thing else. This is exactly on all fours with the 

 cuckoos which over and over again have in his sense 

 recovered the instinct of brooding by sitting on eggs, 

 and these departed from what he says elsewhere is 

 developed out of " occasional habits." There is no 

 escape from this. They cannot both be true and 

 primary instincts. 



Mr. Darwin is here dealing with modifications due 

 directly to man's intervention. Dr. Russel Wallace, 

 with his own characteristic clearness, has given 

 warning that nothing can be more unsafe than to 

 argue from such instances to wild-nature, yet surely 

 one general law may be assumed as here controlling 

 both. If certain birds under the direct manipulation 

 of man, and for his own purposes, lose a certain 

 "primitive instinct," and one of the strongest, may 

 we not assume in the case of a wild bird, that it has 

 lost its strong instinct of the same character from the 

 same or similar general causes, that certain changes, 

 certain influences arose upon it at a certain period, 

 broadly corresponding to those that we find can be 



