the least
sensation of taste. The same may be observed with respect to any
other sapid body, which, unless it is strongly acrid or irritating,
produces no effect on any other part than the tongue; but if it is
possessed of much acrimony, it then not only affects the palate, and
uvula, but even the oesophagus.

The tongue is a muscular substance, placed in the mouth, connected by
one end with the adjacent bones and cartilages, while the other end
remains free, and easily moveable. The tongue is furnished,
particularly on its upper surface, with innumerable nervous papillae,
which are much larger than those I described as belonging to the
skin. These papillae are of a conical figure, and extremely sensible,
forming, without doubt, the true organ of taste; other papillae are
found between them, which are partly conical, and partly cylindrical.

Over the papillae of the tongue is spread a single mucous, and
semipellucid covering, which adheres firmly to them, and serves the
purpose of a cuticle.

Under these papillae are spread the muscles which make up the fleshy
part of the tongue: these are extremely numerous, and by their means
the tongue possesses the power of performing a great variety of
motions with surprising velocity.

The arteries leading to the tongue are extremely numerous; and, when
injected with a red fluid, the whole substance appears of a beautiful
red.

The tongue is likewise furnished with a large supply of nerves, some
of which undoubtedly serve to supply its muscles with nervous energy,
while others terminate in the papillae, and form the proper organ of
taste: this office seems to be performed by the third branch of the
fifth pair of nerves. The papillae, before described, are formed or
composed of a number of small nerves, arteries, and veins, firmly
united together by cellular substance. These papillae are excited to
action by the application of any sapid body; in consequence of which
they receive a greater supply of blood, become enlarged, and vastly
more sensible.

The structure of the tongue differs in different animals, which
likewise possess corresponding differences with respect to taste. In
those quadrupeds, in which it is armed with sharp points, the sense
of taste is by no means acute. The same is the case with birds and
reptiles, whose tongues are very dry and rough.

In a former lecture I took notice of a liquor which is secreted by
the glands of the mouth and neighbouring parts