preservation and of the continuation of the species which we observe
throughout creation, and by the heroic self-abandonment with which
the individual will sacrifice welfare, and even life, at the bidding
of instinct. We see this when we think of the caterpillar, and how
she repairs her cocoon until she yields to exhaustion; of the bird,
and how she will lay herself to death; of the disquiet and grief
displayed by all migratory animals if they are prevented from
migrating. A captive cuckoo will always die at the approach of
winter through despair at being unable to fly away; so will the
vineyard snail if it is hindered of its winter sleep. The weakest
mother will encounter an enemy far surpassing her in strength, and
suffer death cheerfully for her offspring's sake. Every year we see
fresh cases of people who have been unfortunate going mad or
committing suicide. Women who have survived the Caesarian operation
allow themselves so little to be deterred from further childbearing
through fear of this frightful and generally fatal operation, that
they will undergo it no less than three times. Can we suppose that
what so closely resembles demoniacal possession can have come about
through something engrafted on to the soul as a mechanism foreign to
its inner nature, {135} or through conscious deliberation which
adheres always to a bare egoism, and is utterly incapable of such
self-sacrifice for the sake of offspring as is displayed by the
procreative and maternal instincts?

We have now, finally, to consider how it arises that the instincts of
any animal species are so similar within the limits of that species--
a circumstance which has not a little contributed to the engrafted-
mechanism theory. But it is plain that like causes will be followed
by like effects; and this should afford sufficient explanation. The
bodily mechanism, for example, of all the individuals of a species is