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 becomes so close as
not to be distinguished. If Mozart, instead of playing the pianoforte
at three years old with wonderfully little practice, had played a tune
with no practice at all, he might truly be said to have done so
instinctively. But it would be the most serious error to suppose that
the greater number of instincts have been acquired by habit in one
generation, and then transmitted by inheritance to succeeding
generations. It can be clearly shown that the most wonderful instincts
with which we are acquainted, namely, those of the hive-bee and of many
ants, could not possibly have been thus acquired.
It will be universally admitted that instincts are as important as
corporeal structure for the welfare of each species, under its present
conditions of life. Under changed conditions of life, it is at least
possible that slight modifications of instinct might be profitable to a
species; and if it can be shown that instincts do vary ever so little,
then I can see no difficulty in natural selection preserving and
continually accumulating variations of instinct to any extent that may
be profitable. It is thus, as I believe, that all the most complex and
wonderful instincts have originated. As modifications of corporeal
structure arise from, and are increased by, use or habit, and are
diminished or lost by disuse, so I do not doubt it has been with
instincts. But I believe that the effects of habit are of quite
subordinate importance to the effects of the natural selection of what
may be called accidental variations of instincts; that is of variations
produced by the same unknown causes which produce slight deviations of
bodily structure.
No complex instinct can possibly be produced through
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