142 STERILITY FROM Chap. XVIII. 



When conception takes place nnder confinement, the young 

 are often born dead, or die soon, or are ill-formed. This 

 frequently occurs in the Zoological Gardens, and, according to 

 Eengger, with native animals confined in Paraguay. The 

 mother's milk often fails. We may also attribute to the dis- 

 turbance of the sexual functions the frequent occurrence of 

 that monstrous instinct which leads the mother to devour her 

 own offspring, — a mysterious case of perversion, as it at first 

 appears. 



Sufficient evidence has now been advanced to prove that 

 animals when first confined are eminently liable to suffer in 

 their reproductive systems. We feel at first naturally inclined 

 to attribute the result to loss of health, or at least to loss of 

 vigour ; but this view can hardly be admitted when we 

 reflect how healthy, long-lived, and vigorous many animals 

 are under captivity, such as parrots, and hawks when used for 

 hawking, chetahs when used for hunting, and elephants. The 

 reproductive 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. The failure of animals to breed 

 under confinement has been sometimes attributed exclusively 

 to a failure in their sexual instincts : this may occasionally 

 como into play, but there is no obvious reason why this 

 instinct should be especially liable to be affected with per- 

 fectly tamed animals, except, indeed, indirectly through the 

 reproductive system itself being disturbed. Moreover, 

 numerous cases have been given of various animals which 

 couple freely under confinement, but never conceive; or, if 

 they conceive and produce young, these are fewer in number 

 than is natural to the species. In the vegetable kingdom 

 instinct of course can play no part ; and we shall presently see 

 that plants when removed from their natural conditions are 

 affected in nearly the same manner as animals. Change of 

 climate cannot be the cause of the loss of fertility, for, whilst 

 many animals imported into Europe from extremely different 

 climates breed freely, many others when confined in their 

 native land are completely sterile. Change of food cannot be 



