igrate and to lay her eggs in other birds' nests.
An action, which we ourselves should require experience to enable us to
perform, when performed by an animal, more especially by a very young
one, without any experience, and when performed by many individuals in
the same way, without their knowing for what purpose it is performed,
is usually said to be instinctive. But I could show that none of these
characters of instinct are universal. A little dose, as Pierre Huber
expresses it, of judgment or reason, often comes into play, even in
animals very low in the scale of nature.

Frederick Cuvier and several of the older metaphysicians have compared
instinct with habit. This comparison gives, I think, a remarkably
accurate notion of the frame of mind under which an instinctive action
is performed, but not of its origin. How unconsciously many habitual
actions are performed, indeed not rarely in direct opposition to our
conscious will! yet they may be modified by the will or reason. Habits
easily become associated with other habits, and with certain periods
of time and states of the body. When once acquired, they often remain
constant throughout life. Several other points of resemblance between
instincts and habits could be pointed out. As in repeating a well-known
song, so in instincts, one action follows another by a sort of rhythm;
if a person be interrupted in a song, or in repeating anything by rote,
he is generally forced to go back to recover the habitual train of
thought: so P. Huber found it was with a caterpillar, which makes a very
complicated hammock; for if he took a caterpillar which had completed
its hammock up to, say, the sixth stage of construction, and put it into
a hammock completed up only to the third stage, the caterpillar simply
re-performed the fourth, fifth, and sixth stages of construction.
If, however, a caterpillar were taken out of a hammock made up, for
instance, to the third stage, and were put into one finished up to the
sixth stage, so that much of its work was already done for it, far from
feeling the benefit of this, it was much embarrassed, and, in order to
complete its hammock, seemed forced to start from the third stage, where
it had left off, and thus tried to complete the already finished work.
If we suppose any habitual action to become inherited--and I think
it can be shown that this does sometimes happen--then the resemblance
between what originally was a habit and an instinct becom