eject their castings in cavities left in the ground, or in the old
burrows instead of piling them over the mouths of their burrows, and they
cannot collect objects on the surface by which the mouths might be
protected. So again on a recently disinterred pavement of a Roman villa
at Abinger (hereafter to be described) the worms pertinaciously opened
their burrows almost every night, when these had been closed by being
trampled on, although they were rarely able to find a few minute stones
wherewith to protect them.
_Intelligence shown by worms in their manner of plugging up their
burrows_. If a man had to plug up a small cylindrical hole, with such
objects as leaves, petioles or twigs, he would drag or push them in by
their pointed ends; but if these objects were very thin relatively to the
size of the hole, he would probably insert some by their thicker or
broader ends. The guide in his case would be intelligence. It seemed
therefore worth while to observe carefully how worms dragged leaves into
their burrows; whether by their tips or bases or middle parts. It seemed
more especially desirable to do this in the case of plants not natives to
our country; for although the habit of dragging leaves into their burrows
is undoubtedly instinctive with worms, yet instinct could not tell them
how to act in the case of leaves about which their progenitors knew
nothing. If, moreover, worms acted solely through instinct or an
unvarying inherited impulse, they would draw all kinds of leaves into
their burrows in the same manner. If they have no such definite
instinct, we might expect that chance would determine whether the tip,
base or middle was seized. If both these alternatives are excluded,
intelligence alone is left; unless the worm in each case first tries many
different methods, and follows that alone which proves possible or the
most easy; but to act in this manner and to try different methods makes a
near approach to intelligence.
In the first place 227 withered leaves of various kinds, mostly of
English plants, were pulled out of worm-burrows in several places. Of
these, 181 had been drawn into the burrows by or near their tips, so that
the foot-stalk projected nearly upright from the mouth of the burrow; 20
had been drawn in by their bases, and in this case the tips projected
from the burrows; and 26 had been seized near the middle, so that these
had been drawn in transversely and were much crumpled. Therefore 80 per
cent. (always using the nearest whole number) had been drawn in by the
tip, 9 per cent. by the base or foot-stalk, and 11 per cent. transversely
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