268 THE GENESIS OF SPECIES. [CHAP. 



characters long inherited, as the grandchildren of Ayles- 

 bury ducks, removed to a distant part of England, com- 

 pletely lost their early habit of incubation, and hatched 

 their eggs at the same time with the common ducks of the 

 same place." 1 



Mr. Darwin quotes Mr. Bartlett as saying : " It is re- 

 markable that lions breed more freely in travelling collec- 

 tions than in the zoological gardens ; probably the constant 

 excitement and irritation produced by moving from place 

 to place, or change of air, may have considerable influence 

 in the matter." 2 



Mr. Darwin also says : " There is reason to believe that 

 insects are affected by confinement like the higher animals," 

 and he gives examples. 3 



Again, he gives examples of change of plumage in the 

 linnet, bunting, oriole, and other birds, and of the temporary 

 modification of the horns of a male deer during a voyage. 4 



Finally, he adds that these changes cannot be attributed 

 to loss of health or vigour, " when we reflect how healthy, 

 long-lived, and vigorous many animals are under cap- 

 tivity, such as parrots, and hawks when used for hawking, 

 chetahs when used for hunting, and elephants. The re- 

 productive organs themselves are not diseased ; and the 

 diseases from which animals in menageries usually perish 

 are not those which in any way affect their fertility. No 

 domestic animal is more subject to disease than the sheep, 

 yet it. is remarkably prolific. .... It would appear that 

 any change in the habits of life, whatever these habits 

 may be, if great enough, tends to affect in an inexplicable 

 manner the powers of reproduction." 



1 "Animals and Plants under Domestication," vol. ii. p. 25. 



2 Ibid. p. 151, 3 Ibid. p. 157.. 4 Ibid. p. 158. 



