mind. Our
inductive reasoning in this matter is very uncertain, for we can only
judge the mental power of animals by their acts. The brain, and
consequently the mind, of the higher mammals being less highly
organized than that of man, their sexual psychology is also more
primitive, and differs from ours in proportion to the cerebral
development of the species. Comparative anatomy confirms this fact in
the whole series of organisms which possess a central nervous system.
The psychology of the higher apes is thus nearer our own than that of
the dog; the psychology of the dog resembles ours more than that of
the rabbit, etc.

On the other hand, the highly developed cerebral organization of man,
although it has complicated the mental irradiations of his sexual
appetite, has not always ennobled them; on the contrary, it has often
directed them into pernicious paths. We have seen in Chapter VI
numerous and striking proofs of the degeneration, brutality and
cruelty of the manifestations of the human sexual appetite, and we
shall study them further in Chapter VIII. Comparative biology shows us
that the sexual appetite is transformed into love in very different
ways. In order to avoid the immensity of detail of comparative biology
I shall only give a few examples.

While the female spider often kills and eats the male, monkeys, and
parrots give proof of such a great mutual attachment that when one of
the conjoints dies the other sinks into complete despair, ceases to
eat, and perishes in its turn.

In this domain we find singular adaptations to special conditions of
existence. Among the bees and ants, a third class of individuals, or
neuters, formed by differentiation of females, do not copulate, and
lay at the most a few eggs which are not fecundated and which
occasionally develop by parthenogenesis.

Among the termites, another species of social ants, a similar state of
things exists, but the neuters, or workers, are derived from the male
sex as well as the female and their sexual organs are quite
rudimentary. The third sex, or worker, not only has a cerebral
development superior to the sexual individuals, but also inherits the
social sympathetic irradiations of the sexual appetite, which results
in his devotion to a brood which is not his own. Among the social
insects the males are little more than flying sexual organs, which
after copulation are incapable of leading an independent existence and
die of hunger and exhaus