is made to tremble; for Bishop Stanley states (as I hear from Mr.
Moorhouse) that a young peewit kept in confinement used to stand on one
leg and beat the turf with the other leg until the worms crawled out of
their burrows, when they were instantly devoured. Nevertheless, worms do
not invariably leave their burrows when the ground is made to tremble, as
I know by having beaten it with a spade, but perhaps it was beaten too
violently.
The whole body of a worm is sensitive to contact. A slight puff of air
from the mouth causes an instant retreat. The glass plates placed over
the pots did not fit closely, and blowing through the very narrow chinks
thus left, often sufficed to cause a rapid retreat. They sometimes
perceived the eddies in the air caused by quickly removing the glass
plates. When a worm first comes out of its burrow, it generally moves
the much extended anterior extremity of its body from side to side in all
directions, apparently as an organ of touch; and there is some reason to
believe, as we shall see in the next chapter, that they are thus enabled
to gain a general notion of the form of an object. Of all their senses
that of touch, including in this term the perception of a vibration,
seems much the most highly developed.
In worms the sense of smell apparently is confined to the perception of
certain odours, and is feeble. They were quite indifferent to my breath,
as long as I breathed on them very gently. This was tried, because it
appeared possible that they might thus be warned of the approach of an
enemy. They exhibited the same indifference to my breath whilst I chewed
some tobacco, and while a pellet of cotton-wool with a few drops of
millefleurs perfume or of acetic acid was kept in my mouth. Pellets of
cotton-wool soaked in tobacco juice, in millefleurs perfume, and in
paraffin, were held with pincers and were waved about within two or three
inches of several worms, but they took no notice. On one or two
occasions, however, when acetic acid had been placed on the pellets, the
worms appeared a little uneasy, and this was probably due to the
irritation of their skins. The perception of such unnatural odours would
be of no service to worms; and as such timid creatures would almost
certainly exhibit some signs of any new impression, we may conclude that
they did not perceive these odours.
The result was different when cabbage-leaves and pieces of onion were
employed, both of which are devoured with much relish by worms. Small
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