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. The organs of
nutrition are also of necessity present in them all. They differ,
however, in character because of differences of the habitats in
which they get their subsistence.
In the Cephalopoda there are two teeth, enclosing what is called the
mouth; and inside this mouth is a flesh-like substance which
represents a tongue and serves for the discrimination of pleasant
and unpleasant food. The Crustacea have teeth corresponding to those
of the Cephalopoda, namely their anterior teeth, and also have the
fleshy representative of a tongue. This latter part is found,
moreover, in all Testacea, and serves, as in sanguineous animals,
for gustatory sensations. Similarly provided also are the Insects. For
some of these, such as the Bees and the Flies, have, as already
described, their proboscis protruding from the mouth; while those
others that have no such instrument in front have a part which acts as
a tongue inside the mouth. Such, for instance, is the case in the Ants
and the like. As for teeth, some insects have them, the Bees and the
Ants for instance, though in a somewhat modified form, while others
that live on fluid nutriment are without them. For in many insects the
teeth are not meant to deal with the food, but to serve as weapons.
In some Testacea, as was said in the first treatise, the organ which
is called the tongue is of considerable strength; and in the Cochli
(Sea-snails) there are also two teeth, just as in the Crustacea
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