5. Of respiration: Breathe freely and deeply of pure air and spend a part of each day out of doors.
6. Of nervous poise: Suppress wasteful and useless forms of nervous activity, avoid nervous strain, and practice cheerfulness.
7. Of cleanliness: Keep the body and its immediate surroundings clean.
8. Of restraint: Abstain from the unnecessary use of[pg 393] drugs as well as from the practice of any form of activity known to be harmful to the body.
9. Of elimination: Observe all the conditions that favor the regular discharge of waste materials from the body.
Obedience to these laws is of vast importance in the proper management of the body. They should, indeed, be so thoroughly impressed upon the mind as to become fixed habits. There are, however, other conditions that relate to this problem, and it is to these that we now turn. These conditions have reference more specifically to
The Prevention of Disease.—While the average length of life is not far from thirty-five years, the length of time which the average individual is capable of living is, according to some of the lowest estimates, not less than seventy years. This difference is due to disease. People do not, as a rule, die on account of the wearing out of the body as seen in extreme old age, but on account of the various ills to which flesh is heir. It is true that many people meet death by accident and not a few are killed in wars, but these numbers are small in comparison with those that die of bodily disorders. The prevention of disease is the greatest of all human problems. Though the fighting of disease is left largely to the physician, much is to be gained through a more general knowledge of its causes and the methods of its prevention.
Causes of Disease.—Disease, which is some derangement of the vital functions, may be due to a variety of causes. Some of these causes, such as hereditary defects, are remote and beyond the control of the individual. Others are the result of negligence in the observance of well-recognized hygienic laws. Others still are of the nature of influences, such as climate, the house in which one[pg 394] lives, or one's method of gaining a livelihood, that produce changes in the body, imperceptible at the time, but, in the long run, laying the foundations of disease. And last, and most potent, are the minute living organisms, called microbes or germs, that find their way into the body. Although there are two general kinds of germs, known as bacteria (one-celled plants) and protozoa (one-celled animals), most of our germ diseases are caused by bacteria.
Effects of Germs.—While there are many kinds of germs that have no ill effect upon the body and others that are thought to aid it in its work, there are many well-known varieties that produce effects decidedly harmful. They gain an entrance through the lungs, food canal, or skin, and, living upon the fluids and tissues, multiply with great rapidity until they permeate the entire body. Not only do they destroy the protoplasm, but they form waste products, called toxins, which act as poisons. Diseases caused by germs are known as infectious, or contagious, diseases.[129] The list is a long one and includes smallpox, measles, diphtheria, scarlet fever, typhoid fever, tuberculosis, la grippe, malaria, yellow fever, and others of common occurrence. In addition to the diseases that are well pronounced, it is probable that germs are responsible also for certain bodily ailments of a milder character.[130]
[pg 395]Avoidance of Germ Diseases.—The problem of preventing diseases caused by germs is an exceedingly difficult one and no solution for all diseases has yet been found. One's chances of avoiding such diseases, however, may be greatly enhanced: