Yet the wasp does not feed upon caterpillars herself, nor has she ever
seen a wasp provide them for her future offspring. She has never seen a
worm such as will spring from her egg, nor can she know that her egg
will produce a worm; and besides, she herself will be dead long before
the unknown worm can be in existence. Therefore she works blindly;
without knowing that her work is to subserve any useful purpose, she
works to a purpose both definite and important; and her acts are
uniform with those of all solitary wasps that have lived before her or
that will live after her; so that we are compelled to refer these
untaught actions to some constant impulse connected with the special
organization of the wasp,--an innate tact, uniform throughout the
species, of which we, not possessing anything of the kind, can form
only a poor conception, but which we call instinct.

There have been some philosophers, however, who have exercised their
ingenuity in tracing so-called instinctive actions to the operation of
experience. The celebrated Doctor Erasmus Darwin gave, as an
illustration of this view, his opinion that the young of animals know
how to swallow from their experience of swallowing _in utero_. Without
going into any refutation of this position, we would only remark, in
passing, that the act of swallowing is not an instinctive action at
all, but a purely mechanical one. Would not Doctor Darwin have rejoiced
greatly, if he could have brought to the support of his theory the
observation of our own great naturalist, Agassiz, who, knowing the
savage snap of one of the large, full-grown Testudinata, is said to
have asserted, that, under the microscope, he has seen the juvenile
turtle snapping precociously _in embryo_?

But not only is instinct prior to all experience, it is even superior
to it, and often leads animals to disregard it,--the spontaneous