ntral
nerve-cord. Experiments lead me to believe that these are organs of
audition.

When I tap the earth of my vermicularium with a pencil, the unmutilated
worms will come to the surface; but, when the organs described above are
removed, the worms so mutilated will not respond to the tapping, but
will remain in their tunnel. The worms are not appreciably impaired by
such mutilation; on the contrary, they seem to thrive as well as those
to which the knife has not been applied.

In creatures which possess, in all probability, the senses of touch,
taste, smell, sight, and hearing, we would naturally expect to find some
evidences of conscious determination; and we do.

Certain leaves are the favorite food of earth-worms, while certain other
leaves are eaten by them, but not with avidity. When these two kinds of
leaves are given to worms, they will carefully select the favorite food
and will ignore the other, thus unmistakably evincing conscious choice.
Their avoidance of light is probably the result of conscious
determination, and not reflex, as some observers maintain.

Oysters taken from a bank never uncovered by the sea, open their shells,
lose the water within, and soon die; but oysters kept in a reservoir and
occasionally uncovered learn to keep their shells closed, and live much
longer when taken out of the water. This is an act of intelligence due
directly to experience without even the factor of heredity.[33] It is an
instance of almost immediate adaptation to surrounding circumstances.

[33] Dicquemase, _Journal de Physique_, Vol. XXVIII. p. 244; quoted
also by Darwin, MS.; by Bingley, _Animal Biography_, Vol. III. p. 454;
and by Romanes, _Animal Intelligence_, p. 25.

A gentleman fixed a land-snail, with the mouth of the shell upward, in a
chink of a rock. The animal protruded its foot to the utmost extent,
and, attaching it above, tried to pull the shell vertically in a
straight line. Then it stretched its body to the right side, pulled, and
failed to move the shell. It then stretched its foot to the left side,
pulled with all of its strength, and released the shell. There were
intervals of rest between these several attempts, during which the snail
remained quiescent.[34] Thus we see that it exerted force in three
directions, never twice in the same direction, which fact shows
conscious determination and no slight degree of intelligence.

[34] Consult Romanes, _Animal Intelligence_, p. 26.

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