A Treatise on Domestic Economy; For the Use of Young Ladies at Home and at School

it out again, through the _aorta_, to all parts of the body. It then makes another circuit through every part, ministering to the wants of all, and is afterwards again brought 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,