Whatever the conditions under which one lives, or whatever his abstract knowledge of foods and sanitation, the health of the individual resolves itself at last into a question of his personal habits; and some of these personal questions must be considered in a book of this character.

Exercise.

One of the commonly accepted facts of hygiene is that, for the best development and for the perfect health of the human body, a certain amount of exercise should be taken by each part of the body. This is true not only for the larger muscles, such as those of the arms and legs, but also for the muscles of those internal organs less frequently considered. Experiments have been made by tying up some part of the body, such as the forearm, with the result that, in the course of a few weeks, its functions have been so lessened that its usefulness is temporarily at an end. But the general effect of exercise on the body, aside from the beneficial results on the particular muscles engaged, is to promote the building up of new lung tissue. Oxygen is received from the lungs through the blood and is carried to the different parts of the body, where it serves the useful purpose of carrying off the waste products of the different organs. If the lung action is inadequate, if deep breathing in fresh air is not practiced, or if, through laziness, no exercise is taken, then the amount of oxygen supplied will be deficient and the body will be loaded up with the toxic products resulting from decomposition. The exact effect of exercise upon the lung action may be seen from the fact that under ordinary circumstances a man breathes about 480 cubic inches of air per minute. If he is walking at the rate of 4 miles an hour, he inhales air at 5 times this rate, and if he is walking at the rate of 6 miles an hour, inspiration increases to seven times this rate, or 3360 cubic inches of air passes through his lungs per minute instead of 480, as when at rest.

Of course, it is assumed that in the country a person has no lack of exercise, and that of all men the farmer is in least need of exercise. But, as a matter of fact, the exercise which he gets is irregular and confined to certain sets of muscles, rather than to the development of the whole body. Agility, for instance, quickness of action and immediate control of the muscles, is far less common in the country than is supposed, although there is probably no lack in the actual power of the muscles. It is common observation that among farmers an erect carriage is less frequently seen than an awkward, shuffling gait. The fact is, that exercise, to be beneficial, should affect not one set of muscles, but all the muscles of the body, because the continuous exercise of one set, while leading first to growth, results later in demolition and waste. When, however all the muscles of the body are exercised, there is no demolition or waste, but a healthy growth throughout. Regular exercise is beneficial, not merely to the muscles involved, but also to the other organs of the body. Exercise sharpens the appetite, makes digestion more perfect, and increases the absorptive power of the intestinal membranes; conversely, lack of exercise, which is found in the country in the winter, lessens both the digestive power and the appetite.

Clothing.

Little need be said on this subject, since the amount of clothing needed varies so greatly with the vitality of the individual. It has already been pointed out that in rural communities the death-rate from pneumonia, bronchitis, and similar respiratory troubles is much higher than in urban communities, and it is quite possible that deficient or unsuitable clothing is practically responsible for this.

The object of clothing is twofold: to protect the body against the weather, particularly against changes in the weather, and secondly, to protect the body against injury. Included in the former are the defenses against the elements of cold, wet, and heat; while the protection against injury is chiefly a matter of shoes. As has been pointed out, a large part of the food consumed by the body is utilized in the production of heat, whereby the body temperature is maintained at about 98 degrees Fahrenheit. A large part of this heat is continually being lost from and through the skin by radiation and evaporation, and evidently some regulating influence must be provided so that the amount of heat given off may be adjusted to variations of the external temperature. To be sure, the skin itself acts as a regulator, since a rise in temperature causes the blood vessels on the surface to distend so that a larger quantity of blood is distributed over the surface and thereby more freely evaporated. Fall of temperature, on the contrary, causes a contraction of the blood vessels and therefore a reduction in the evaporation. But this is not sufficient where external temperature undergoes wide variations, as in the northern and central parts of the United States, and a modification of the clothing is a necessary supplement. The main object of clothing, then, is not to keep out cold or heat, but to preserve and make uniform the evaporation from the body. It is an agent of the same sort as food in so far as the body temperature is concerned, and without doubt light clothing requires a greater amount of food; while, on the other hand, warm clothing will make possible a lighter diet.

The best non-conductor of heat is still air, and if one could always remain in quiet air, no clothing of any sort would be necessary, even in the most severe weather, because the air itself would serve as a garment and would prevent radiation from the body. Therefore, loose, porous garments containing air in their folds and pores are much warmer than a single, tightly woven garment, and the same material made up in three or four thicknesses will give the body far more warmth than an equal weight of texture made up in a single thickness. Similarly, a tight garment is much less warm than a loose one. A practical demonstration of this fact is found in the comparative lack of warmth in an old, much-washed, quilted, bed blanket which is very heavy but quite lacking in warmth compared with a light fluffy woolen blanket, newly purchased.

Much has been written on the advantages of woolen underwear, on the ground that since clothing is intended to retain the body heat and since wool acts as a more effective non-conductor of heat than either cotton or linen, therefore the woolen undergarment is of the greatest value. Another argument urged in favor of woolen undergarments is that they check the chill resulting from excessive perspiration, since the non-conducting power of wool prevents any rapid evaporation of perspiration responsible for the lower temperatures. For this reason, woolen undergarments are always recommended for those climbing mountains or in occupations where violent exercise is likely to be followed by rest or quiet in cold air. The objection to woolen undergarments at all times is that with sensitive skins irritation may take place, and the odd saying of Josh Billings becomes pertinent, namely, that "the only thing that a wool shirt is good for is to make a man scratch and forget his other troubles." Underwear woolen only in part may take the place of all-wool garments and have the further advantage of being less expensive. The amount of clothing worn in winter depends, or should depend, on the character of the occupation of the wearer.

Formerly, heavy woolen underclothes were almost universally worn throughout the winter without regard to the employment of the individual. When an out-of-door occupation was pursued a large part of the time or when the temperature indoors was hardly above freezing, then heavy clothing was essential; but now that much time is spent in a well-heated house or office, heavy clothing is as objectionable as overheated rooms, and the comfort and health of the body will be much better preserved by not increasing the weight of clothing except when exposed to the outer air. It must be remembered, however, that old persons, whose circulation is impaired and who are forced to lead sedentary lives, will always have difficulty in maintaining the body heat unless the outer temperature is high, and for such, woolen undergarments are very useful. The outer garments in winter, to be efficient, must have two qualities, namely, an impervious surface so that winds may not penetrate and a loose open weave in which air may be held so that warmth may be secured.

Rubber boots, although very common in the country, are not desirable as a foot covering, because they do not allow the perspiration to evaporate, but rather hold the foot in a moist condition very detrimental to it. Rubber-cloth overshoes or arctics are much better than rubber boots, and felt overshoes are equally satisfactory. Chilblains are fostered by the use of rubber boots, and cloth shoes are a great relief when the feet are thus affected.

Ventilation of bedroom.

Since the agitation for fresh air has become so extensive and the knowledge of the dangers of tuberculosis so widespread, much more attention has been given to the ventilation of bedrooms, and whereas formerly the night air was religiously excluded from a sleeping room, it is not at all uncommon now for a window to be kept wide open, even through the coldest nights of winter. From what has already been said on the subject of ventilation, it is plain that to breathe over and over one's expired air is not healthy, and while it is possible that a bedroom may be so large that the concentration of the organic matter in the air may not affect an individual sleeping in the room, yet in most cases it must be admitted that the bedroom is so small or the number of people in the bedroom so large that this possibility does not exist. It is, again, possible that the structure of the house may be so poor that it is not necessary to open a window to get plenty of fresh air; the writer remembers sleeping in rooms where, with the windows shut, paths of snow across the floor in the morning showed the intimate connection between the inside and the outside of the room.

But the tendency nowadays is to build better houses, to cover the walls with paper, to put on double windows, and even to paste up the cracks to make the room as air-tight as possible. To sleep in such a room without a window open may not be committing suicide, but it is a deliberate method of reducing the vitality, of insuring a headache or a numbed and stupid mental condition, and of loading up the system with poisons which ought to be eliminated by the oxygen which fresh air supplies. It would add many years to the lives of the people of this country if, from childhood up, the habit was formed of sleeping with the window open. Nor need one fear that a cold would result from such exposure. A cheesecloth screen in the window prevents any draft and yet allows perfect ventilation. The face is trained to all kinds of exposure without any danger of catching cold, and there is no reason why, if the bed clothing be sufficient, the night air should not be thoroughly enjoyed without danger. Of course, the bed clothing must be sufficient; two lightly woven blankets are always better than one heavy one. Wool is better than cotton; if a cotton quilt is used, it should be loose and not tied tightly.

Bathing.

An important function of the skin is to expel objectionable elements coming from the breaking down of the cells and from digestive processes; the skin is quite as important a factor in getting rid of this waste matter as those other processes more commonly considered in this connection. This action goes on most energetically when the secretion of perspiration is abundant and when the temperature of the surrounding air is so high that perspiration does not evaporate as rapidly as discharged. All these secretions contain more or less solid material which, unless removed, accumulates on the surface of the skin to clog up the glands and, in some cases, to putrefy and decay. It is this decay of organic matter on the surface of the skin which causes the odors plainly noticeable in a crowd, particularly in the winter time. This accumulation can be prevented only by frequent bathing and by wearing clean clothes, and there is no surer indication of a proper self-respect than the habit of cleanliness, both as to one's person and one's clothes. There is also the very practical feature that cleanliness is an effective method of discouraging infection and disease, partly by the removal of scurf and partly by the greater healthfulness of the skin thereby induced.

Baths have always served as therapeutic agents, and evidences of their use may be found in Roman paintings and in Egyptian sculpture to-day. But from our standpoint it is their hygienic importance that is insisted upon. Ordinarily, the temperature of the bath should be between 90 and 100 degrees, and enough soap should be used to counteract the oily nature of the deposits on the skin.

Unfortunately, facilities for bathing, except in summer, have not been generally supplied to detached houses in the country. Plumbing in most houses has been lacking, but in these days bath-rooms are being installed with surprising rapidity, and the conveniences resulting are enjoyed as soon as they are understood. Only a few days ago, the writer was told of a small village of perhaps two or three hundred persons where this last summer one house, the first in the village, was provided with a bath-room, to the great interest of all the villagers. The convenience and comfort involved were immediately appreciated, and the plumber, who came in from a neighboring city twenty miles away, secured contracts for and installed twelve bath-rooms in twelve houses before he was allowed to leave the village. This same interest is everywhere noticeable, and the lack of bathing throughout the winter, formerly, alas, so common, is now giving way to a greater cleanliness, thereby improving the health and character of the inhabitants.

A great deal has been written about the value of a cold bath, particularly in the morning, and many people, from a sense of duty, suffer what is almost torture taking a shower bath or a cold plunge bath on rising. When a cold bath (which should not last more than a few seconds) is followed by a good reaction, that is, when after drying, a distinct glow is felt, there is no objection to its use, and undoubtedly it has a tonic effect for those whose vitality is able to endure the shock. But cold baths for their tonic effect are desirable only when the individual is assured of their lasting benefits. Nor must one judge of the effects by the immediate results, inasmuch as the splendid feeling which follows may be succeeded by a period of depression lasting the rest of the day; in which case, the total effect of the cold bath is bad rather than good. Baths for cleanliness are everywhere desirable, and their frequency should depend upon the individual, his constitution, habits, and work; upon the season and temperature; and on the conveniences for bathing in the house. Baths for tonic effect are not necessary, and if not a pleasure, may very properly be omitted.

One other point to be noted is that no practice is of more value in reducing the ravages of contagious diseases than a frequent and conscientious washing of one's hands. For germs are most certainly transmitted from one person to another, and it is accomplished more frequently by the hands than by any other part of the body.

The invitation, therefore, to a guest to wash his hands before dinner is really an invitation for him to disinfect himself or to get rid of the germs which he is carrying, in order that the host and his family may not be infected during the meal. The guest owes it to his host always to accept the invitation, whether he thinks he needs it or not. Doctors recognize the necessity, and it is surprising to observe how many times during the day a doctor washes his hands, even though he may not come in contact with any particularly infectious disease. An ordinary man, on the other hand, washes his hands only when he thinks they are dirty, although his daily occupation may expose the skin of his hands to infection many times worse than that which the doctor experiences.

Mouth breathing.

Children have sometimes wondered why they were made with both mouths and noses, since they could breathe equally with either, and many years have gone by before they realized that breathing through the mouth was not intended, but that the exclusive province of the nose was to furnish air to the lungs. The reason for nose breathing rather than mouth breathing is twofold. In the first place, no provision for removing or filtering out germs from the air is made in the mouth, whereas in the nose the crooked passages, the moist surfaces, and the hairlike growths all tend to strain out any germs normally in the inspired air.

Further, breathing through the mouth has a tendency to induce inflammation in the tonsils and in the air passage connecting with the ear. This inflammation develops into those growths known as adenoids, which, when enlarged sufficiently, close the nostril entirely and prevent its normal use. A recent examination made by the New York Board of Health of 150 school children, all in some way abnormal, showed that 137 had either adenoids or enlarged tonsils. Example after example could be given of school boys and girls whose mental and moral development has been markedly retarded because of mouth breathing. One need only look at a child or adult who constantly keeps his or her mouth open to be impressed by the listless, vacant, inert appearance of the face thus disfigured. Figure 74 shows a photograph of a schoolgirl just before an operation and the characteristic expression due to adenoids is plainly marked. Earache is largely due to adenoids or to inflammation that rapidly leads to adenoids, and Mr. William H. Allen, Secretary of the Bureau of the New York Municipal Research, reports that in 415 villages of New York State, 12 per cent of the children living there were found to be mouth breathers. Whenever a child is unable to breathe through his nose, is slow in talking, and then speaks with a stuffy accent, calls "nose" "dose," has a narrow upper jaw, and is either deaf or has inflamed eyes, it is practically certain that enlarged tonsils and a well-developed growth of adenoids are present and should be removed. Not merely do these growths interfere with the mental and physical development of the child, but they also make him more susceptible to contagious diseases, particularly those of the lungs and bronchial tubes.

The removal of adenoids is a simple operation, lasting not over a minute, and the result of the operation is in some cases almost miraculous. The medical inspectors of the New York City schools consider the removal of adenoids as a most important part of their work, and groups of children are regularly taken from the schools by the principal to the clinic at the hospital, where one after another tonsils are cut off or adenoids are removed, all fright and commotion being avoided by the gift of five cents as a reward.

Eyes.

Another evidence of advancing knowledge in matters pertaining to sanitary hygiene is shown in the greater attention given to the eyes, particularly of children. Such incidental troubles as headache, sleeplessness, or biliousness are frequently due to weak or strained eyes, and in the case of school children a great deal of the alleged insubordination, backwardness, and truancy of the children is caused by their being unable to see written instructions or explanations.

It is not likely that this increased difficulty with the eyes is a new thing, but rather that both physicians and laymen are more careful as well as more expert in diagnosing the trouble. The New York State Board of Health in the fall of 1907 sent out cards for testing the eyes of school children to 446 incorporated towns. The results of using these cards in 415 schools were returned and showed clearly that nearly half the children of school age in the state had optical defects. A similar test in Massachusetts recently discovered 22 per cent of the school children with defective vision, and this knowledge in itself is an advance inasmuch as it suggests to each individual or to all parents that deficient vision is common and that good eyesight is not a thing to be assumed.

In the country it is more difficult, perhaps, to realize these deficiencies, because the constant outdoor life acts as an offset to the strain during the time when close work is required, and perhaps the distance from a competent oculist serves to postpone the time of consultation, but no greater folly can be indulged in than to suffer inflamed eyes, persistent headache, and imperfect vision, if it is possible in any way to secure the services of an oculist.

Never is it worth while to buy from a jeweler, a grocer, or a hardware store a pair of spectacles, much less to buy them from an itinerant peddler, since an oculist, with his particular apparatus, can measure the seeing ability of each eye and fit each eye with the necessary lens to restore normal vision. It is better to have no glasses than to have glasses that are wrong.

Teeth.

A curious result of the recent studies among school children with defective eyes and ears has been the discovery that bad teeth were quite as important in their relation to general health as either bad eyes or ears. One eye specialist went so far as to say that the teeth of school children should be attended to first, because thus many of the eye troubles would disappear.

As has already been pointed out, the first, step in digestion is taken in the mouth, and careful chewing is not less important than the other parts of the digestive process. If one's teeth are not adapted to chewing, if they are bunched, crowded, loose, or isolated, the appearance of the teeth is the least objectionable feature. The real importance comes from the fact that with such teeth perfect mastication is impossible. The teeth themselves harbor germs which actually infect the food and favor its putrefaction. With decayed teeth, infectious diseases find a ready entrance to the lungs, nostrils, stomach, glands, ears, nose, and membranes. At every act of swallowing, germs are carried into the stomach. Mouth breathers cannot get one breath of uncontaminated air, and dental clinics, organized and conducted in the interests of the health of school children, have been altogether too little inaugurated. The use of a toothbrush should be encouraged in children as soon as they are four years old, and its habitual use twice a day is most desirable for every one.

Only regular examination by the dentist can keep the teeth in good condition, and periodic visits at least once a year to a dentist's office, not to the kind advertised by Indians where they are willing to extract teeth without pain, free, but where a regularly qualified dentist practices, should be the habit. Armenian children, who prize and covet beautiful teeth, are taught to clean their teeth always after eating, if only an apple or a piece of bread between meals, and while probably our American customs would hardly make this possible, there is no question but that a persistent and frequent use of the toothbrush will help much in reducing dentist bills.

Sleep.

From many standpoints sleep is the most wonderful attribute of the human body. Our familiarity, from our earliest years, with sleep, closes our eyes to its strange, its awful power. We know that every human being, once in twenty-four hours, will normally close his eyes and for a certain length of time be as oblivious to things present as if already in the sleep of death. It is a common belief that sleep is nature's provision for restoring tired muscles and jaded nerves, and for building up new tissue in cell and corpuscle. Excessive exertion produces a numbness and exhaustion so that the body becomes "dead tired," and sleep brings back life and elasticity. And yet some parts of the body, some muscles and some organs, do not stop work during sleep, and apparently feel no bad results for their continuous lifelong exertion. Thus, the lungs, whose muscular action is estimated at the rate of one thirtieth of a horse power, have no rest day or night, seemingly without weariness. Similarly, the heart is continually forcing blood under a pressure of about three pounds through the arteries without cessation from birth to death.

Why do the muscles of the arm and leg tire and need sleep as a restorer, while those of the heart and lungs are independent of sleep? Dr. W. H. Thomson, in his book on "Brain and Personality," finds an answer to this question in the fact that the latter do their work independently of the human consciousness, while the former are stimulated and directed by the will. He points out that fatigue comes in proportion to the intensity of the mental effort expended. A baby, to whom everything is strange, whose consciousness is absolutely zero at birth, however well developed his body, sleeps five sixths of the time because of the mental efforts needed in his simplest bodily acts. Brain work, the most absorbing task of consciousness, is always the most compelling in the matter of sleep. Not the muscles themselves but the attention, the skill, the mental effort required to direct those muscles, Dr. Thomson says, constitute the reason for sleep, a reason which, to those who labor only with their hands, must seem unutterably sad. He says that while muscle work is the commonest and the simplest, so it is also the most poorly paid and the most degrading, and that while brain work is ennobling and the highest type of labor, it is so difficult of attainment and produced only by such grievous toil that most of us shirk it, even while reproaching ourselves at our lack of capacity and purpose. The pathetic burden of unfulfilled possibilities, he says, is the curse of labor, and only in sleep does man have temporary oblivion through which, for a time, he forgets his work and, as it were, uses sleep as an anÆsthetic for the pain of labor, to rise therefrom each morning ready to carry his burdens for another day.

Lack of sleep, to those whose brains are active, speedily brings nervous disaster, and the consciousness, from being the active superintendent of the body, becomes inert, and the body drifts like a boat without a pilot. Lack of sleep to those whose work is muscular means a numbness in the nerve cells which guide those muscles, so that they disobey the will or act unreasonably and without direction. But too much sleep, like over-indulgence in any anÆsthetic, is only shirking that duty and avoiding that effort to which the higher life calls us, and the sluggard who sleeps more than the tired nerves need is allowing himself to sink deeper and deeper into a slough of despond. He forgets his toil in sleep, but it is only by active, conscious effort when awake that his work may be lifted to the higher plane where the brain is active, where work ceases to be mechanical and a burden, and where that greatest reward of personal satisfaction can be obtained.