141 STERILITY FROM Chap. XVIII. 



their own pollen, but can easily be fertilised by that of a 

 distinct species. Finally, we must conclude, limited as the 

 conclusion is, that changed conditions of life have an especial 

 power of acting injuriously on the reproductive system. The 

 whole case is quite peculiar, for these organs, though not 

 diseased, are thus rendered incapable of performing their 

 proper functions, or perform them imperfectly. 



Sterility of Domesticated Animals from changed conditions. — "With 

 respect to domesticated animals, as their domestication mainly 

 depends on the accident of their breeding freely under captivity, 

 we ought not to expect that their reproductive system would be 

 affected by any moderate degree of change. Those orders of 

 quadrupeds and birds, of which the wild species breed most readily 

 in our menageries, have afforded us the greatest number of domes- 

 ticated productions. Savages in most parts of the world are fond 

 of taming animals; 68 and if any of these regularly produced young, 

 and were at the same time useful, they would be at once domesti- 

 cated. If, when their masters migrated into other countries, they 

 were in addition found capable of withstanding various climates, 

 they would be still more- valuable; and it appears that the animals 

 which breed readily in captivity can generally withstand different 

 climates. Some few domesticated animals, such as the reindeer and 

 camel, offer an exception to this rule. Many of our domesticated 

 animals can bear with undiminished fertility the most unnatural 

 conditions ; for instance, rabbits, guinea-pigs, and ferrets breed in 

 miserably confined hutches. Few European dogs of any kind 

 withstand the climate of India without degenerating, but as long 

 as they survive, they retain, as I hear from Dr. Falconer, their 

 fertility; so it is, according to Dr. Daniell, with English dogs 

 taken to Sierra Leone. The fowl, a native of the hot jungles of 

 India, becomes more fertile than its parent-stock in every quarter 

 of the world, until we advance as far north as Greenland and 

 Northern Siberia, where this bird will not breed. Both fowls and 

 pigeons, which I received during the autumn direct from Sierra 

 Leone, were at once ready to couple. 69 I have, also, seen pigeons 



68 Numerous instances could be nesians of the Samoan Islands tamed 



given. Thus Livingstone (' Travels,' pigeons ; and the New Zealanders, as 



p. '217) states that the King of the Mr. Mantell informs me, kept various 



Barotse, an inland tribe which never kinds of birds. 



had any communication with white a9 For analogous cases with the 



men. was extremely fond of taming fowl, see Reaumur, ' L'Art de faire 



animals, and every young antelope was Eclore,' &c, 1749, p. 243; and Col. 



brought to him. Mr. Galton informs Sykes, in 'Proc. Zoolog. Soc.,' 1832, 



me that the Damaras are likewise &e. With respect to the fowl not 



fond of keeping pets. The Indians of breeding in northern regions, sec 



South America follow the same habit. Latham's ' Hist, of Birds,' vol. viii., 



Capt. Wilkes states that the Poly- 1823, p. 169. 



