f the _moral effects_
of this practice, he adds, "Smoking and chewing tobacco, by rendering
water and other simple liquors insipid to the taste, dispose very much
to the stronger stimulus of ardent spirits; hence the practice of
smoking cigars throughout our country has been followed by the use of
brandy and water as a common drink." A dentist of extensive and
successful practice in the Middle and Western States, after listening to
the reading of this article, said to me, he had a patient, a young lady,
two of whose front teeth had decayed through, laterally, in consequence
of smoking. On removing the caries, he found it impossible to fill her
teeth, because the openings continued through them. He thinks, as do
many others, that the heat of the smoke is a principal cause of the
injury.

Among the conditions upon which the healthy action of the voluntary
organs depends is a due degree of _appropriate exercise_. This is a
_general law_, and holds with reference to the _teeth_ as well as to any
other organ or set of organs. The proper mastication of healthful and
nutritious food constitutes the appropriate exercise of the teeth, and
is a condition upon which _their health_, and the healthy exercise of
the function of _digestion_, alike depend. If from any cause the teeth
of one jaw are removed, the corresponding teeth of the other jaw, being
thus deprived of that exercise which is essential to their health, are
pressed out of the jaw, appear to grow long, become loose in their
sockets, and sometimes fall out. Hence the propriety and advantage of
inserting _artificial teeth_ where the natural ones fail; an event which
rarely happens when they are properly taken care of. I need hardly add
that nuts, and other hard substances that break the enamel, are
injurious to the teeth, and should be avoided.

THE BONES.--The bones constitute the frame-work of the system. They
consist of two substances, being formed of both _animal_ and _earthy_
matter. To the former belongs every thing connected with their _life_
and _growth_, while the latter gives to them _solidity_ and _strength_.
The proportions of the animal and earthy elements of which the bones are
composed vary at different ages. In childhood and early youth, when but
_little strength_ is needed, and _great growth_ of bone is required, the
animal part preponderates. As growth advances the animal part
_decreases_, and the earthy part _increases_. In middle life, when
growth is