ought back by the veins to
receive the fresh chyle from the stomach, and to be purified by the
lungs.

The throbbing of the heart is caused by its alternate expansion and
contraction, as it receives and expels the blood. With one throb, the
blood is sent from the right ventricle into the lungs, and from the left
ventricle into the aorta.

Every time we inspire air, the process of purifying the blood is going
on; and every time we expire the air, we throw out the redundant carbon
and hydrogen, taken from a portion of the blood. If the waist is
compressed by tight clothing, a portion of the lungs be compressed, so
that the air-vessels cannot be filled. This prevents the perfect
purification and preparation of the blood, so that a part returns back
to the heart unfitted for its duties. This is a slow, but sure, method,
by which the constitution of many a young lady is so undermined that she
becomes an early victim to disease and to the decay of beauty and
strength. The want of _pure air_ is another cause, of the debility of
the female constitution. When air has been rendered impure, by the
breath of several persons, or by close confinement, it does not purify
the blood properly. Sleeping in close chambers, and sitting in crowded
and unventilated schoolrooms, are frequent causes of debility in the
constitution of young persons.

OF THE SKIN.

The skin is the covering of the body, and has very important functions
to perform. It is more abundantly supplied with nerves and blood-vessels
than any other part; and there is no spot of the skin where the point of
the finest needle would not pierce a nerve and blood-vessel. Indeed, it
may be considered as composed chiefly of an interlacing of minute nerves
and blood-vessels, so that it is supposed there is more nervous matter
in the skin, than in all the rest of the body united, and that the
greater portion of the blood flows through the skin.

The whole animal system is in a state of continual change and
renovation. Food is constantly taken into the stomach, only a portion of
which is fitted for the supply of the blood. All the rest has to be
thrown out of the system, by various organs designed for this purpose.
These organs are,--the lungs, which throw off a portion of useless
matter when the blood is purified; the kidneys, which secrete liquids
that pass into the bladder, and are thrown out from the body by that
organ; and the intestines, which carry off the useless and m