on Taste. It would be remarkable
if tobacco should fail to injure the sense of taste. The effect produced
upon the tender papillae of the tongue by the nicotine-loaded juices and
the acrid smoke tends to impair the delicate sensibility of the entire
surface. The keen appreciation of fine flavors is destroyed. The once
clear and enjoyable tastes of simple objects become dull and vapid; thus
highly spiced and seasoned articles of food are in demand, and then
follows continued indigestion, with all its suffering.

Again, the burning, almost caustic effect of the stronger alcoholic
drinks, and the acrid pungency of tobacco smoke, are disastrous to the
finer perceptions of both taste and odors.

322. Smell. The sense of smell is lodged in the delicate
membrane which lines the nasal cavities. The floor, sides, and roof of
these cavities are formed by certain bones of the cranium and the face.
Man, in common with all air-breathing animals, has two nasal cavities.
They communicate with the outer air by two nostrils opening in front,
while two other passages open into the pharynx behind.

To increase the area of the air passages, the two light, spongy turbinated
bones, one on each side, form narrow, winding channels. The mucous
membrane, with the branches of the olfactory nerve, lines the dividing
wall and the inner surfaces of these winding passages. Below all these
bones the lower turbinated bones may be said to divide the olfactory
chamber above from the ordinary air passages.

[Illustration: Fig. 126.--Distribution of Nerves over the Interior of the
Nostrils. (Outer wall.)

A, branches of the nerves of smell--olfactory nerve, or ganglion;
B, nerves of common sensation to the nostril;
E, F, G, nerves to the, palate springing from a ganglion at C;
H, vidian nerve, from which branches
D, I, and J spring to be distributed to the nostrils.
]

The nerves which supply the nasal mucous membrane are derived from the
branches of the fifth and the first pair of cranial nerves,--the
olfactory. The latter, however, are the nerves of smell proper, and are
spread out in a kind of thick brush of minute nerve filaments. It is in
the mucous membrane of the uppermost part of the cavity of the nostril
that the nerve endings of smell proper reside. The other nerves which
supply the nostrils are those of common sensation (sec. 271).

323. The Sense of Smell. The sense of smell is excited by the contact
of odorous particles