rmed me that he
had often observed analogous facts. The horns of a male deer (_Cervus
Canadensis_) during the voyage from America were badly developed; but
subsequently in Paris perfect horns were produced.

When conception takes place under confinement, the young are often born
dead, or die soon, or are ill-formed. This frequently occurs in the
Zoological Gardens, and, according to Rengger, with native animals confined
in Paraguay. The mother's milk often fails. We may also attribute to the
disturbance 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 {159}
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 too 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 come into play, but there is no obvious reason why
this instinct should be especially liable to be affected with perfectly
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. Ch