contortions. Judging by their eagerness for certain kinds of food,
they must enjoy the pleasure of eating. Their sexual passion is
strong enough to overcome for a time their dread of light. They
perhaps have a trace of social feeling, for they are not disturbed
by crawling over each other's bodies, and they sometimes lie in
contact. According to Hoffmeister they pass the winter either
singly or rolled up with others into a ball at the bottom of their
burrows. {17} Although worms are so remarkably deficient in the
several sense-organs, this does not necessarily preclude
intelligence, as we know from such cases as those of Laura
Bridgman; and we have seen that when their attention is engaged,
they neglect impressions to which they would otherwise have
attended; and attention indicates the presence of a mind of some
kind. They are also much more easily excited at certain times than
at others. They perform a few actions instinctively, that is, all
the individuals, including the young, perform such actions in
nearly the same fashion. This is shown by the manner in which the
species of Perichaeta eject their castings, so as to construct
towers; also by the manner in which the burrows of the common
earth-worm are smoothly lined with fine earth and often with little
stones, and the mouths of their burrows with leaves. One of their
strongest instincts is the plugging up the mouths of their burrows
with various objects; and very young worms act in this manner. But
some degree of intelligence appears, as we shall see in the next
chapter, to be exhibited in this work,--a result which has
surprised me more than anything else in regard to worms.

Food and Digestion.--Worms are omnivorous. They swallow an
enormous quantity of earth, out of which they extract any
digestible matter which it may contain; but to this subject I must