A Handbook of Health

If they could be combined with the natural, window system of ventilation, they would be less objectionable; but the first demand of nearly all of them is that the windows must be kept shut for fear of breaking the circuit of their circulation. Any system of ventilation, or anything else, that insists on all windows being kept shut is radically wrong. It is only fair to say, however, that most of these systems of ventilation attempt the impossible, as well as the undesirable thing of keeping people shut up too long. No room can be, or ought to be, ventilated so that its occupants can stay in it all day long without discomfort. In ventilating, we ought to ventilate the people in the room, as well as the room itself. This can only be done successfully by turning the people out of doors, at least every two or three hours if grown-ups, and every hour or so if children. That is what school recesses are for, and they might well be longer and more frequent.

The first and chief thing necessary for the good ventilation of houses and schools is plenty of windows, which are also needed to give proper light for working purposes, and to let in the only ever-victorious enemy of germs and disease—sunlight.

Secondly, and not less important, the windows should fit properly, and be perfectly hung and balanced, so that the sash will come down at a finger's touch, stay exactly where it is put, and go up again like a feather, instead of having to be pried loose, wrested open, held in place with a stick, and shoved up, or down again, only with a struggle.

There should be, if possible, windows on two sides of every room, or, if not, a large transom opening into a hall which has plenty of windows in it. With this equipment and a good supply of heat, any room can be properly ventilated and kept so. But it will not ventilate itself. Ventilation, like the colors of the great painter Turner, must be "mixed with brains"; and those brains must be in the room itself, not down in the basement. In the schoolroom, each teacher and pupil should regard the ventilation of the room as the most important single factor in the success of their work. The teacher has a sensitive thermometer and guide in, first, her own feelings and, second, the looks and attention of her pupils. There should be vacant seats or chairs in every room so that those too near the window in winter can move out of the strong current of cold air.

Windows should reach well up toward the ceiling and be opened at the top, because the foul air given off from the lungs at the temperature of the body is warmer than the air of the room and consequently rises toward the ceiling. It is just as important in ventilation to let the foul air out as to let the fresh air in. In fact, one is impossible without the other. Air, though you can neither see it, nor grasp it, nor weigh it, is just as solid as granite when it comes to filling or emptying a room. Not a foot, not an inch of it can be forced into a room anywhere, until a corresponding foot or inch is let out of it somewhere. Therefore, never open a window at the bottom until you have opened it at the top. If you do, the cold fresh air will pour in onto the floor, while the hot foul air will rise and bank up against the ceiling in a layer that gets thicker and thicker, and comes further and further down, until you may be actually sitting with your head and shoulders in a layer of warm foul air, and your body and feet in a pool of cool pure air. Then you will wonder why your head is so hot, and your feet so cold!

Currents and Circulation of Air. In fact, this tendency of hot air to rise, and of cold air to sink, or rush in and take its place, which is the mainspring of nature's outdoor system of ventilation, is one of our greatest difficulties when we wall in a tiny section of the universe and call it a room. The difficulty is, of course, greatest in winter time, when the only pure air there is—that out of doors—is usually cold. This is one of the few points at which our instincts seem to fail us. For when it comes to a choice between being warm or well ventilated, we are sadly prone to choose the former every time. Still we would much rather be warm and well ventilated than hot and stuffy, and this is what we should aim for.

The main problem is the cost of the necessary fuel, as it naturally takes more to heat a current of air which is kept moving through the room, no matter how slowly, than it does a room full of air which is boxed in, as it were, and kept from moving on after it has been warmed. The extra fuel, however, means the difference between comfort and stuffiness, between health and disease. Fortunately, the very same cold which makes a room harder to heat makes it easier to ventilate. When air is warmed, it expands and makes a "low pressure," which sucks the surrounding cooler air into it, as in the making of winds; so that the warmer the air inside the room, or the colder the air outside of it, which is practically the same thing, the more eagerly and swiftly will the outdoor air rush into it. So keen is this draft, so high this pressure, that some loosely-built houses and rooms, with only a few people in them, will in very cold weather be almost sufficiently ventilated through the natural cracks and leaks without opening a window or a door at all. And what is of great practical importance, an opening of an inch or two at the top of a window will admit as much fresh air on a cold day as an opening of a foot and a half in spring or summer, so swiftly does cold air pour in.

Bearing this in mind, and also that it is always best to ventilate through as many openings as possible, both to keep drafts of cold air from becoming too intense, and to give as many openings for the escape of the foul air as possible, there will be little difficulty in keeping any room which has proper window arrangements well ventilated in winter. An opening of an inch at the top of each of three windows is better than a three-inch opening at the top of one. But you must use your brains about it, watching the direction of the wind, and frequently changing the position of the window sashes to match the changes of heat in the room, or of cold outside.

No arrangement of windows, however perfect, is likely to remain satisfactory for more than an hour at a time, except in warm weather. This watchfulness and attention takes time, but it is time well spent. "Eternal vigilance" is the price of good ventilation, as well as of liberty; and you will get far more work done in the course of a morning by interrupting it occasionally to go and raise or lower a window, than you will by sitting still and slaving in a stuffy, ill-smelling room.

Plenty of Heat Needed. Any method of heating—open fireplace, stove, hot air, furnace, hot water, or steam—which will keep a room with the windows open comfortably warm in cold weather is satisfactory and healthful. The worst fault, from a sanitary point of view, that a heating system can have is that it does not give enough warmth, so that you are compelled to keep the windows shut. Too little heat is often as dangerous as too much; for you will insist on keeping warm, no matter what it may cost you in the future, and a cold room usually means hermetically sealed windows. Remember that coal is cheaper than colds, to say nothing of consumption and pneumonia.

Ventilating the Bedroom. The same principles that apply to ventilating a living-room or day-room apply to ventilating a bedroom. Here you can almost disregard drafts, except in the very coldest weather, and, by putting on plenty of covering, sleep three hundred days out of the year with your windows wide open and your room within ten degrees of the temperature outdoors. You need not be afraid of catching cold. On the contrary, by sleeping in a room like this you will escape three out of four colds that you usually catch. Sleeping with the windows wide open is the method we now use to cure consumption, and it is equally good to prevent it.

No bedroom window ought to be closed at the top, except when necessary to keep rain or snow from driving in. Close the windows for a short time before going to bed, and again before rising in the morning, to warm up the room to undress and dress in; or have a small inside dressing-room, with your bed out on a screened balcony or porch. But sleep at least three hundred nights of the year with the free air of heaven blowing across your face. You will soon feel that you cannot sleep without it. In winter, have a light-weight warm comforter and enough warm, but light, blankets on your bed, and leave the heat on in the room, if necessary—but open the windows.

COLDS, CONSUMPTION, AND PNEUMONIA

Disease Germs. In all foul air there are scores of different kinds of germs—many of them comparatively harmless, like the yeasts, the moulds, the germs that sour milk, and the bacteria that cause dead plants and animals to decay. But among them there are a dozen or more kinds which have gained the power of living in, and attacking, the human body. In so doing, they usually produce disease, and hence are known as disease germs.

These germs—most of which are known, according to their shape, as bacilli ("rod-shaped" organisms), or as cocci (round, or "berry-shaped" organisms)—are so tiny that a thousand of them would have to be rolled together in a ball to make a speck visible to the naked eye. But they have some little weight, after all, and seldom float around in the air, so to speak, of their own accord, but only where currents of air are kept stirred up and moving, without much opportunity to escape, and especially where there is a good deal of dust floating, to the tiny particles of which they seem to cling and be borne about like thistle-down. This is one reason why dusty air has always been regarded as so unwholesome, and why a very high death rate from consumption, and other diseases of the lungs, is found among those who work at trades and occupations in which a great deal of dust is constantly driven into the air, such as knife-grinders, stone-masons, and printers, and workers in cotton and woolen mills, shoddy mills, carpet factories, etc.

In cleaning a room and its furniture, it is always best to use a carpet sweeper, a vacuum cleaner, or a damp cloth, as much as possible, the broom as little as may be, and the feather duster never. The two latter stir up disease germs resting peacefully on the floor or furniture, and set them floating in the air, where you can suck them into your lungs.

There are three great groups of disease germs which may be found floating in the air wherever people are crowded together without proper ventilation—for most of these disease germs cannot live long outside of the body, and hence come more or less directly from somebody else's lungs, throat, or nose. The most numerous, but fortunately the mildest group, of these are the germs of various sorts which give rise to colds, coughs, and sore throats. Then there are two other exceedingly deadly germs, which kill more people than any other disease known to humanity—the bacillus of consumption, and the coccus of pneumonia.

Our best protection against all these is, first, to have our rooms well ventilated, well lighted, and well sunned; for most of these germs die quickly when exposed to direct sunlight, and even to bright, clear daylight. The next most important thing is to avoid, so far as we can, coming in contact with people who have any of these diseases, whether mild or severe; and the third is to build up our vigor and resisting power by good food, bathing, and exercise in the open air, so that these germs cannot get a foothold in our throats and lungs.

Colds. Two-thirds of all colds are infectious, and due, not to cold pure air, but to foul, stuffy air, with the crop of germs that such air is almost certain to contain. They should be called "fouls," not "colds." They spread from one person to another; they run through families, schools, and shops. They are accompanied by fever, with headache, backache, and often chills; they "run their course" until the body has manufactured enough antitoxins to stop them, and then they get well of their own accord. This is why so many different remedies have a great reputation for curing colds.

If you "catch cold," stay in your own room or in the open air for a few days, if possible, and keep away from everybody else. You only waste your time trying to work in that condition, and will get better much more quickly by keeping quiet, and will at the same time avoid infecting anybody else. Get your doctor to tell you what mild antiseptic to use in your nose and throat; and then keep it in stock against future attacks. Often it is advisable to rest quietly in bed a few days, so as not to overtax the body in its weakened condition.

Keep away from foul, stuffy air as much as possible, especially in crowded rooms; bathe or splash in cool water every morning; sleep with your windows open; and take plenty of exercise in the open air; and you will catch few colds and have little difficulty in throwing off those that you do catch. Colds are comparatively trifling things in themselves; but, like all infections however mild, they may set up serious inflammations in some one of the deeper organs—lungs, kidneys, heart, or nervous system, and frequently make an opening for the entrance of the germs of tuberculosis or pneumonia. Don't neglect them; and if you find that you take cold easily, find out what is wrong with yourself, and reform your unhealthful habits.

HOW TO CONQUER CONSUMPTION

Different Forms of Tuberculosis. The terrible disease tuberculosis is the most serious and deadly enemy which the human body has to face. It kills every year, in the United States, over a hundred and fifty thousand men, women, and children—more lives than were lost in battle in the four years of our Civil War. It is caused by a tiny germ—the tubercle bacillus—so called because it forms little mustard-seed-like lumps, or masses, in the lungs, called tubercles, or "little tubers." For some reason it attacks most frequently and does its greatest damage in the lungs, where it is called consumption; but it may penetrate and attack any tissue or part of the body. Tuberculosis of the glands, or "kernels," of the neck and skin, is called scrofula; tuberculosis of the hip is hip-joint disease; and tuberculosis of the knee, white swelling. "Spinal disease" and "hunch-back" are, nine times out of ten, tuberculosis of the backbone. Tuberculosis of the bowels often causes fatal wasting away, with diarrhea, in babies and young children; and tuberculosis of the brain (called tubercular meningitis) causes fatal convulsions in infancy.

Tuberculosis of the Lungs—How to Keep it from Spreading. Tuberculosis of the lungs is the most dangerous of all forms, both because the lungs appear to have less power of resistance against the tubercle bacillus, and also because from the lung, the bacilli can readily be coughed up and blown into the air again, or spit onto the floor, to be breathed into the lungs of other people, and thus give them the disease. Two-thirds of all who die of tuberculosis die of the pulmonary, or lung, form of the disease, popularly called consumption.

The first thing then to be done to put a stop to this frightful waste of human life every year is to stop the circulation of the bacillus from one person to another. This can be done partially and gradually by seeing that every consumptive holds a handkerchief, or cloth, before his mouth whenever he coughs; that he uses a paper napkin, pasteboard box, flask, or other receptacle whenever he spits; and that these things in which the sputum is caught are promptly burned, boiled, or otherwise sterilized by heat. The only sure and certain way, however, of stopping its spread is by placing the consumptive where he is in no danger of infecting any one else. And as it fortunately so happens that such a place—that is to say, a properly regulated sanatorium, or camp—is the place which will give him his best chance of recovery, at least five times as good as if he were left in his own home, this is the plan which is almost certain to be adopted in the future. Its only real drawback is the expense.

But when you remember that consumption destroys a hundred and fifty thousand lives every year in this country alone, and that it is estimated that every human life is worth at least three thousand dollars to the community, you will see at once that consumption costs us in deaths alone, four hundred and fifty million dollars a year! And when you further remember that each person who dies has usually been sick from two to three years, and that two-thirds of such persons are workers, or heads of families, and that tens of thousands of other persons who do not die of it, have been disabled for months and damaged or crippled for life by it, you can readily see what an enormous sum we could well afford to pay in order to stamp it out entirely.

One of the most important safeguards against the disease is the law that prevents spitting in public places. Not only the germs of consumption, but those of pneumonia, colds, catarrhs, diphtheria, and other diseases, can be spread by spitting. The habit is not only dangerous, but disgusting, unnecessary, and vulgar, so that most cities and many states have now passed laws prohibiting spitting in public places, under penalty of fine and imprisonment.

The next best safeguard is plenty of fresh air and sunlight in every room of the house. These things are doubly helpful, both because they increase the vigor and resisting power of those who occupy the rooms and might catch the disease, and because direct sunlight, and even bright daylight, will rapidly kill the bacilli when it can get directly at them.

How great is the actual risk of infection in crowded, ill-ventilated houses is well shown by the reports of the tuberculosis dispensaries of New York and other large cities. Whenever a patient comes in with tuberculosis, they send a visiting nurse to his home, to show him how best to ventilate his rooms, and to bring in all the other members of the family to the dispensary for examination. No less than from one-fourth to one-half of the children in these families are found to be already infected with tuberculosis. The places where we look for our new cases of tuberculosis now are in the same rooms or houses with old ones. A careful consumptive is no source of danger; but alas, not more than one in three are of that character.

It has been estimated that any city or county could provide proper camps, or sanatoria, to accommodate all its consumptives and cure two-thirds of them in the process, support their families meanwhile, and stop the spread of the disease, at an expense not to exceed five dollars each per annum for five years, rapidly diminishing after that. If this were done, within thirty years consumption would probably become as rare as smallpox is now. Some day, when the community is ready to spend the money, this will be done, but in the mean time, we must attack the disease by slower and less certain methods.

Why the Fear and Danger of Consumption have been Lessened. Terrible and deadly as consumption is, we no longer go about in dread of it, as people did twenty-five years ago, before we knew what caused it; for we know now that it is preventable and that two-thirds of the cases can be cured after they develop. The word consumption is no longer equivalent to a sentence of death. The deaths from tuberculosis each year have diminished almost one-half in the last forty years, in nearly every civilized country in the world; and this decrease is still going on.

The methods which have brought about this splendid progress, and which will continue it, if we have the intelligence and the determination to stick to them, are:—First, the great improvements in food supply, housing, ventilation, drainage, and conditions of life in general, due to the progress of modern civilization and science, combined with a marked increase in wages in the great working two-thirds of the community. Second, the discovery that consumption is caused by a bacillus, and by that alone, and is spread by the scattering of that bacillus into the air, or upon food, drink, or clothing, to be breathed in or eaten by other victims. Third, increase of medical skill and improved methods of recognizing the disease at a very early stage. A case of consumption discovered early means a case cured, eight times out of ten.

Its Cure and Prevention. Fortunately, the same methods which will cure the disease will also prevent it. The best preventatives are food, fresh air, and sunshine. Eat plenty of nourishing food three times a day, especially of milk, eggs, and meat. Sit or work in a gentle current of air, keep away from those who have the disease, sleep with your windows open, take plenty of exercise in the open air, and you need have little fear of consumption.

In the camps, or sanatoria, for the cure of consumption, these methods are simply carried a little further, to make up for previous neglect. The patients sit or lie out of doors all day long, usually in reclining chairs, in summer under the trees, and in winter on porches, with just enough roof to protect them from rain or snow. They sleep in tents, or in shacks, which are closed in only on three sides, leaving the front open to the south. They dress and undress in a warm room, or the curtains of the tent are dropped, or the shutters of the shack closed night and morning until the room is warmed up. In cold climates they dress day and night almost as if they were going on an arctic relief expedition, and spend twenty-four hours out of the twenty-four in the open air.

They eat three square meals a day, consisting of everything that is appetizing, nutritious, and wholesome, with plenty of butter, or other fats; and in addition, drink from one to three pints of new milk and swallow from six to twelve raw eggs a day. You would think they would burst on such a diet, but they don't; they simply gain from two to four pounds a week, lose their fever and their cough, get rid of their night sweats, and usually in from two to five weeks are able to be up and about the camp, taking light exercise. When they have reached their full, normal, or healthy weight for their height and age, their amount of food is reduced, but still kept at what would be considered full diet for a healthy man at hard work. If sick people can be made well by this open air treatment, those of us that are well ought not be afraid to have a window open all night.

Two-thirds of the treatment that would cure you of consumption will prevent your ever having it. While tuberculosis chiefly attacks the lungs, it is really a disease of the entire body, or system, and cannot attack you if you will keep yourself strong, vigorous, and clean in every sense of the word.

How to Recognize the Disease in its Early Stages. To recognize the disease early is, of course, work for the doctor; but he must be helped by the intelligence of the patient, or the patient's family, or he may not see the case until it is so far advanced as to have lost its best chance of cure. We can now recognize consumption before the lungs are seriously diseased. Among the most useful methods with children is the rubbing or scratching of a few drops of the toxin of the tubercle bacillus, tailed tuberculin, into the skin. If the children are healthy, this will leave no mark, or reddening, at all; but if they have tuberculosis, in two-thirds of the cases it will make a little reddening and swelling like a very mild vaccination. But in order to get any good from this, cases must be brought to a doctor, early, without waiting for a bad cough, or for night sweats.

Signs of Consumption. The signs that ought to make us suspicious of a possible beginning of tuberculosis are first, loss of weight without apparent cause; fever, or flushing of the cheeks, with or without headache, every afternoon or evening; and a tendency to become easily tired and exhausted without unusual exertion. Whenever these three signs are present, without some clear cause, such as a cold, or unusual overwork or strain, especially if they be accompanied by a rapid pulse and a tendency to get out of breath readily in running upstairs, they should make us suspect tuberculosis; and if they keep up, it is advisable to go at once and have the lungs thoroughly examined. Nine cases out of ten, seen at this stage, are curable—many of them in a few months.

Even if we should not have the disease, if we have these symptoms we need to have our health improved; and a course of life in the open air, good feeding, and rest, which would cure us if we had tuberculosis, will build us up and prevent us from developing it.

PNEUMONIA

Its Cause and Prevention. The other great disease of the lungs is pneumonia, formerly known as inflammation of the lungs. This is rapid and sudden, instead of slow and chronic like tuberculosis, but kills almost as many people; and unfortunately, unlike tuberculosis, is not decreasing. In fact in some of our large cities, it is rapidly increasing. Although we know it is due to a germ, we don't yet know exactly how that germ is conveyed from one victim to another. One thing, however, of great practical importance we do know, and that is that pneumonia is a disease of overcrowding and foul air, like tuberculosis; that it occurs most frequently at that time of the year—late winter and early spring—when people have been longest crowded together in houses and tenements; and that it falls most severely upon those who are weakened by overcrowding, under-feeding, or the excessive use of alcohol. How strikingly this is true may be seen from the fact that, while the death-rate of the disease among the rich and those in comfortable circumstances, who are well-fed and live in good houses, is only about five per cent,—that is, one in twenty,—among the poor, especially in the crowded districts of our large cities, the death-rate rises to twenty per cent, or one in five; while among the tramp and roustabout classes, who have used alcohol freely, and among chronic alcoholics, it reaches forty per cent. The same steps should be taken to prevent its spread as in tuberculosis—destroying the sputum, keeping the patient by himself, and thoroughly ventilating and airing all rooms. As the disease runs a very rapid course, usually lasting only from one to three weeks, this is a comparatively easy thing to do.

Though pneumonia is commonly believed to be due to exposure to cold or wet, like colds, it has very little to do with these. You will not catch pneumonia after breaking through the ice or getting lost in the snow, unless you already have the germs of the disease in your mouth and throat, and your constitution has already been run down by bad air, under-feeding, overwork, or dissipation. Arctic explorers, for instance, never catch pneumonia in the Frozen North.

CHAPTER XV

The eyes in the beginning were simply little colored patches of the skin, sunk into the head for the purpose of specializing on the light-rays. The smelling areas of the nose also were pieces of the skin, as were also the ears. Not only so, but—although it is a little hard for you to understand how this could have happened—the whole brain and nervous system is made up of folds of the skin tucked in from the surface of the back; so that we can say that the skin, with the organs that belong to it and have grown from it—the eyes, nose, ears, brain, and nerves—forms the most wonderful part of the body. Everything that we know of the world outside of us is told us by the skin and the look-out organs that have grown out of it. The skin is not only the surface part and coating of the body, far superior to any six different kinds of clothing which have yet been invented, but it is related to, and assists in, the work of nearly half the organs in the body. Not only all that we learn by touch and pressure, but everything that we know of heat and cold, of moisture and dryness, and most of pain, comes to us through our skin, through the little bulbs on the ends of the nerve twigs in it. It also helps the lungs to breathe, the kidneys to purify the blood, and the heart to control the flow of blood through the body.

A healthy skin is of very great importance; and part of this health we can secure directly, by washing and bathing, scrubbing and kneading and rubbing, because the skin lies right on the surface, where we can readily get at it. But, on the other hand, no amount of attention from the outside alone will keep it healthy. All the organs inside the body must be kept healthy if the skin is to be kept in good condition. Although the external washing and cleaning are very important, the greater part of the work of developing a healthy skin and a good complexion must be done from the inside.

The Two Layers which Make Up the Skin. Like our "internal skin," the mucous membrane, which lines our stomach and bowels, the skin is made up of two layers—a deeper, or basement, sheet, woven out of tough strands of fibrous stuff (derma); and a surface layer (epidermis) composed of cells lying side by side like the bricks in a pavement, or the tiles on a floor, and hence called "pavement" (epithelial) cells. These pavement cells are fastened on the basement membrane much as the kernels of corn grow on a cob; only, instead of there being but one layer, as on a cob of corn, there are a dozen or fifteen of them, one above the other, each one dovetailing into the row below it, as the corn kernels do into the surface of the cob. As they grow up toward the surface from the bottom, they become flatter and flatter, and drier, until the outer surface layer becomes thin, fine, dry, slightly greasy scales, like fish-scales, of about the thickness of the very finest and driest bran.

We are continually Shedding our Skin. One way in which the skin keeps itself so wonderfully clean and fresh is by continually shedding from its surface showers of these fine, dry, scaly cells, which drop, or are rubbed off, as they dry. This is the reason why no mark, not even a stain or dye, upon the skin, will stay there long; for no matter how deeply it may have soaked into the layers of the pavement-cells, every cell touched by it will ultimately grow up to the surface, dry up, and fall off, carrying the stain with it.

If you want to make a mark on the skin that will be permanent, you have to prick the colors into it so deeply that they will go through the basement layer and reach cells which will not grow toward the surface. This "pricking-in" operation is known as tattooing; and it is as foolish as it is painful, for blood-poisoning and other diseases may be carried into the system in the process.

Perhaps you will wonder why, if you are shedding these scales from all over your surface every day, you don't see them. This is simply because they are so exceedingly small, thin, and delicate, that you cannot see them unless you get a large number of them together; and when you are changing your clothing, bathing, etc., they are rubbed off and float away. If a part of the body has been shut in—as when a broken arm, for instance, is in a cast, which cannot be changed for several weeks—when finally you take off the bandage, you will find inside it spoonfuls—I had almost said handfuls—of fine scales, which have been shed from the skin and held in by the wrappings.

THE GLANDS IN THE SKIN

Sweat Glands. Like all the pavement (epithelial) surfaces of the body, inside and out, the skin has the power of making glands by dipping down little pouches or pockets into the layers below. In the skin, these little gland-pockets are of two kinds, the sweat glands and the hair glands.

The sweat glands are tiny tubes which go twisting down through the different pavement layers, through the basement layer, and right into the coat of fat, which lies just under the skin. The tube of the sweat gland soaks, or picks, out of the blood some of the waste-stuff—just as the kidney tube does in the kidney,—together with a good deal of water and a small amount of delicate oil, and pours them out on the surface of the body in the form of the "sweat," or perspiration.

As you will remember, when the muscles work hard and pour more waste into the blood, then the heart pumps larger amounts of blood out into the skin; and this causes it to redden. The sweat glands work harder to purify this extra blood, and they pour out the waste and oil and water on the surface. As soon as this water gets upon our hot skin, it begins to evaporate and cool us off, as well as to carry off some of the waste in the form of gas. The trace of oil in the perspiration helps to lubricate the skin and keep it soft; but when too much of it is poured out we have that greasy feeling, which we have all felt after perspiring freely.

From all this cooling and breathing and blood-purifying work going on upon the surface of our skin, you can easily see why it is so important that all our clothing should be loose and porous and that next the skin easily washed; else it will very soon become clogged up and greasy, and shut off the breathing and blood-purifying work of the skin and make it dirty and unhealthy. This continual mist of water, rising and bubbling up through our skin like springs out of a hillside, is another of nature's wonderful ways of cleansing the skin and of preventing any kind of dirt from permanently sticking to or lodging in it. Remember, you do not need to dig below the surface when you wash.

Hair Glands. The other kind of skin glands, the hair glands, are also pouches growing out from the deepest part of the stem of the hair, known as the root, or hair bulb.

From the root of the hairs, two or three little bundles of muscle run up toward the surface of the skin. When these contract, they pull the root of the hair up toward the surface, causing the hair to stand erect, or "bristle," as we say. This is what makes the hair on a dog's or a cat's back stand up when he is angry; but the commonest use of the movement is, when animals are cold, to make their coats stand out so as to hold more air and retain the body-heat better. We have lost most of our hairy coating, but whenever we get chilly, whether from cold or from fright, these little muscles of our hair bulbs contract and pull the hair glands of our skin up toward the surface, so that it looks all "pimply" or "goose-skinned."

Each hair pouch has sprouted out from its sides a pair of tiny pouches, which form oil glands to lubricate the hair and keep it sleek and flexible. It is hard to beat nature at her own game, and her method of oiling the hair is far superior to any hair oil that can be put on from the outside. Keep your hair well brushed and washed, and nature will oil it for you much better than any hair oil or scalp reviver ever invented.[19]

THE NAILS

How the Nails are Made. Another "trade," which our wonderful skin has literally "at its fingers' ends," is that of making nails. Indeed, every kind of scale, armor, fur, feather, and leather coating possessed by bird, beast, or fish was made by, and out of, the skin. Nail-making, however, is one of its simplest feats, as it is carried out merely by turning a little patch, or area, of itself into a horn-like substance. This, the skin of insects, of fishes, of crocodiles, etc., does all over the surface of their bodies; but in animals and birds only a number of little patches at the tips of the toes harden up in this way, to form the claws or nails; and in birds, the beak; and in some animals, the horns. So it is quite correct to call the substance of our nails "horn-like."

In some animals and birds, these little horny patches at the ends of the toes grow out into long, curved hooks, or broad, digging chisels and scoops; but on our own fingers, they simply make a little mould over the finger-tip. If, however, they are protected from being broken off, they will grow four or five inches long; in fact, they are carefully trained to do this by some of the upper classes in China, merely for the purpose of showing that they have never been obliged to degrade themselves, as they foolishly regard it, by working with their hands.

You can easily prove that the nails do grow constantly from the root or base, out toward the tip, by watching, some time when you have pounded one of your nails, how the black or discolored patch in it will grow steadily outward toward the tip, where it will be broken off and shed.

You cannot see the softest and youngest row, or layer, of the nail cells at the base, because a fold of skin, the nail fold, has been doubled, or folded, over them to protect them while they are young and soft. It is not best to push this fold of skin back too much, as, by so doing, you may uncover the young nail cells while they are soft and tender, and expose them to injury. The reason why there is a little whitish crescent at the base of the nail is that the cells of the nail do not grow hard and horn-like and transparent until they have grown out a quarter of an inch or so from under the fold, but at first look whitish, or opaque, like the rest of the skin.

Health Shown by the Color of the Nails. Your nails and your lips are not really any redder, or pinker, than the rest of your skin; but the cells forming them are clear and transparent and allow the red blood to show through. This is why we often look at the nails and lips to see what the color of the blood is like, and how well or badly it is circulating. If the blood is anemic, or thin, then both lips and nails are pale and dull. If the blood is healthy and the circulation good, then the nails are pink, and the lips clear red. If, on the other hand, the circulation is bad, as in some forms of lung disease and heart disease, so that the blood is loaded with carbonic acid until it is blue and dark, then the lips may become purplish or dark blue, and the finger nails nearly the same color.

THE BLOOD-MESH OF THE SKIN

The Blood Vessels under the Skin. Not merely the nails and the lips, but the whole surface of the skin is underlaid with a thick mat, or network, of blood vessels. These vessels are all quite small, so that a cut has to go down completely through the skin, and generally well down into the muscles, before it will reach any blood vessel which will bleed at a dangerous rate. But there are so many of them, and they cover such a wide surface throughout the body, that they are actually capable of holding, at one time, nearly one-tenth of all the blood in the body.

This "water-jacket" coat of tiny blood vessels all over our body has some very important uses: It allows the heart to pump large amounts of blood out to the surface to be purified by the sweat glands, and to breathe out a little of its carbon dioxid and other gas-poisons.

The Skin as a Heat Regulator. Heat, as well as waste, is given off by the blood when it is poured out to the surface; so another most important use of the skin is as a heat regulator. As we have already seen, every movement which we make with our muscles, whether of arms and limbs, heart, or food tube, causes heat to be given off. We very well know, when we work hard at anything, we are likely to "get warmed up." Although a certain amount of this heat is necessary to our bodily health, too much of it is very dangerous.

Just as it is best for the temperature, or heat, of a room to be at about a certain level, somewhere from 60° to 70° F., so it is best for the interior of our bodies to be kept at about a certain heat. This, as we can show by putting a little glass thermometer under the tongue, or in the armpit, and holding it there for a few minutes, is a little over 98° F. (98.4° to be exact); and this we call "body heat," or "blood heat," or "normal temperature." Our body cells are, in one way, a very delicate and sensitive sort of hot-house plants, though tough enough in other respects. Whenever our body heat goes down more than five or six degrees, or up more than two or three degrees, then trouble at once begins. If our temperature goes down, as from cold or starvation, we begin to be drowsy and weak, and finally die. If, on the other hand, our temperature climbs up two, three, or four degrees, then we begin to be dizzy and suffer from headache and say we have "a fever."

A fever, or rise of temperature, that can be noted with a thermometer, is usually due to disease germs of some sort in the body; and most of the discomfort that we suffer is really due more to the poisons (toxins) of the germs than to the mere increase of heat, though this alone will finally work serious damage. However, as we well know from repeated experience, we need only to run or work hard in the sun for a comparatively short time to make ourselves quite hot enough to be very uncomfortable; and if we had no way to relieve ourselves by getting rid of some of this heat, we should either have to stop work at once, or become seriously ill. This relief, however, is just what nature has provided for in this thick coat of blood vessels in our skin; it enables us to throw great quantities of blood out to the surface where it can get rid of, or, as the scientists say, "radiate," its heat. This cooling process is hastened by the evaporation of the perspiration poured out at the same time, as we have seen.

One of the chief things in training for athletics is teaching our skin and heart together to get rid of the heat made by our muscles, as fast, or nearly as fast, as we make it, thus enabling us to keep on running, or working, without discomfort. As soon as we stop running, or working, the heart begins to slow down, the blood vessels in the skin contract and diminish in size, the flush fades, and we begin to cool off. We are not making either as much heat or as much waste as we were, and hence do not need to get rid of so much through our skins.

When we feel cold, just the opposite kinds of change occur in the skin. The blood vessels in the skin contract so as to keep as much of our warm blood as possible in the deeper parts of our body, and prevent its losing heat. As blood showing through the pavement-layer of the skin is what gives us our color, or complexion, our skin becomes pale and pasty-looking; and if all the blood is driven in from the surface, our lips and finger nails will become blue with cold. Here again, by changes in the skin, nature is simply trying to protect herself from the loss of too much heat.

If we exercise briskly, or eat a good warm meal, and thus make more heat inside of our body, then there is no longer any need to save its surface loss in this way; and the blood vessels in our skin fill up, the heart pumps harder, and the warm, rich color comes back to our faces and lips and finger nails.

So perfectly and wonderfully does this skin mesh of ours work, by increasing or preventing the loss of heat, that it is almost impossible to put a healthy man under conditions that will raise or lower his temperature more than about a degree, that is to say, about one per cent above, or below, its healthful level. Men studying this power of the skin have shut themselves into chambers, or little rooms, built like ovens, with a fire in the wall or under the floor, and found that if they had plenty of water to drink and perspired freely, they could stand a temperature of over 150° F. without great discomfort and without raising the temperature of their own bodies more than about one degree. If, however, the air in the chamber was moistened with the vapor of water, or steam, so that the perspiration could no longer evaporate freely from the surface of their bodies, then they could not stand a temperature much above 108° or 110° without discomfort.

Other men, who were trained athletes, have been put to work in a closed chamber, at very vigorous muscular exercise, so as to make them perspire freely. But while a thermometer placed in that chamber showed that the men were giving off enormous amounts of heat to the air around them, another thermometer placed under their tongues showed that they were raising the temperature of their own bodies only about half a degree. One man, however, happened to try this test one morning when he was not feeling very well, and didn't perspire properly, and the thermometer under his tongue went up nearly four degrees.

THE NERVES IN THE SKIN

How We Tell Things from Touch, and Feel Heat and Cold and Pain. Last of all, the skin is the principal organ of the sense of touch, and also of the "temperature sense"—the sense of heat and cold—and of the sense that feels pain. All these feelings are attended to by little bulbs lying in the deeper part of the skin and forming the tips of tiny nerve twigs,[20] which run inward to join larger nerve branches and finally reach the spinal cord. There are millions of these little bulbs scattered all over the surface of the skin, but they are very much thicker and more numerous in some parts than in others; and that is why, as you have often noticed, certain parts of the skin are more sensitive than others. They are thickest, for instance, on the tips of our fingers and on our lips, and fewest over the back of the neck and shoulders, and across the lower part of the hips.[21]

For a long time, it was supposed that all these little nerve-bulbs in the skin did the same kind of work, because they looked, under the microscope, exactly alike; but it was found that they divide the work up among them, so that some of them give their entire attention to heat, and others to cold, others to touch, and others again to pain. So carefully has the work been mapped out among them that they report to different centres in the brain and spinal cord, so that we now understand why, in diseases which happen to attack one or other of these centres, we may lose our sense of heat and cold, as in that terrible disease, leprosy; or our sense of touch, as in paralysis; or we may even, in some very rare cases, lose our sense of pain, and yet have all our other senses perfect.

CHAPTER XVI

The principles upon which garments should be built are two: First, they should fit closely enough to the body and limbs to protect them from either injury or cold, even while free activity of every sort is allowed—you could not wrestle in a blanket or run very far in a sack. Second, they should be thick enough to protect us from cold, and yet at the same time porous enough not to interfere with the natural breathing and ventilating of the skin. A garment should be as loose as possible without interfering with our movements, and as free and as light as can be worn with reasonable warmth and protection. The less clothing you can wear and be comfortable, the better.

We should particularly avoid binding or cramping the chest and the hips and waist. If clothing is too tight about the chest, it interferes both with free movement of the arms and, what is even more important, with the breathing movements of the chest. If too tight about the waist and hips, it badly cripples the lower limbs and interferes with the proper movements of the diaphragm in breathing, and with the passage of the food and the blood through the bowels.

Your instincts are perfectly right that make you dislike to be squeezed or pinched or cramped in any way, or at any point, by your clothing; and if you will only follow these instincts all through your lives, you will be far healthier and happier.

The Texture of Clothing. Just as for ages we have experimented with different kinds of food, so we have with different kinds of material for clothing. We have used the skins of animals; mats woven out of leaves and grasses; the feathers of birds; the skins of fishes; cloths made of wool and of cotton; and even the cocoon spun by certain caterpillars, which we call silk. But of all these materials, practically only two have stood the test of the ages and proved themselves the most suitable and best all-round clothing materials—wool and cotton.

Woolen cloth, woven from the fleece of sheep or goats or camels or llamas or alpacas, has three great advantages, which make it the outside clothing of the human species. First, it is sufficiently tough and lasting to withstand rips and tugs and ordinary wear and tear; second, it is warm—that is, it retains well the body heat; and third, it is porous, so that it will allow gases and perspiration from the surface of the body to pass through it in one direction, and air for the skin to breathe, in the other.