A Handbook of Health

No clothing, of course,—not even fur,—has any warmth in itself; it simply has the power of retaining, or keeping in, the warmth of the body that it covers. The best and most effective way of retaining the body warmth is to surround the body with a layer of dead, or still, air, which is the best non-conductor of heat known. Hence, porous garments, like loosely-woven flannels, blankets, and other woolen cloths, are warm because they contain or hold large amounts of air in their spongy mesh.

The reason why furs are so warm is that their soft, furry under-hairs, or "pelt" as the furriers call it, entangle and hold an enormous amount of air. The fur of ordinary sealskin, for instance, is about half an inch deep; and ninety per cent of this half-inch is air. If you wet it, its fur "slicks down" to almost nothing, although the most drenching wetting will not wash all the air out of it, but still leaves a dry layer next to the skin. The fur of mink skin, coon skin, or wolf skin, is an inch thick; and nearly eighty per cent of this thickness is air.

The great advantage for clothing purposes of wool over fur is that the wool is porous through and through, while the fur is borne upon, and backed by, a layer of leather—the skin of the animal upon which it grew—which layer, after tanning and curing, becomes almost absolutely air-tight.

As a matter of fact, furs are worn mostly for display and are most unwholesome and undesirable garments. The only real excuse for their use, save for ornament in small pieces or narrow strips, is on long, cold rides in the winter, and among lumbermen, frontiersmen, and explorers. They hold in every particle of perspiration and poisonous gas thrown off by the skin, and if worn constantly, make it pale, weak, and flabby; and the moment we take them off, we take cold.

For outer garments and general wear, nothing yet has been discovered equal to wool, particularly at the cooler times of the year. But for under wear, in the hotter seasons and climates, wool has certain disadvantages. It is likely to be rough and tickling to most skins, which makes it uncomfortable, especially in warm weather. It is also difficult and troublesome to wash woolens without shrinking them; and, as soon as they do shrink, not only do they become uncomfortably tight, but the natural pores in them which make them so valuable close up, and they become almost air-tight. Finally, when loaded with perspiration, woolens easily become offensive, so that they must be frequently changed and washed; and as they are also high in price, it is easily seen that there are practical drawbacks to their use.

Cotton is much softer and pleasanter to the skin than wool, is cooler in hot weather, is much cheaper, and is very easily washed without losing either its shape or its porousness. It can be so woven as to be almost as porous as wool, and to retain that porousness even when saturated with perspiration. It does not soak up and retain the oils and odors of perspiration in the way that wool does; and on the whole, for under wear, and for general wear at the warm seasons of the year, it is not only more comfortable, but far more healthful, than wool. Persons of fair health and reasonably vigorous outdoor habits, whose skins are well bathed and ventilated, can wear properly woven cotton or linen undergarments the whole year round with perfect safety.

Linen and silk both make admirable and healthful under wear, if woven with a properly porous mesh. Linen has the advantage of remaining more porous than cotton, when moist with perspiration. But for healthy people they have no advantages over cotton that are not offset by their higher prices.

BATHS AND BATHING

Bathing as a Means of Cleanliness. It has been said that one of the reasons why man lost his hairy coat was that he might be able to wash himself better and keep cleaner. However this may be, he has to wash a great deal oftener than other animals, most of whom get along very well with currying, licking, and other forms of dry washes, and an occasional swim in a river or lake.

You can readily see how necessary for us washing is, when you remember the quarts of watery perspiration, which are poured out upon our skins every day, and the oily and other waste matters, some of them poisons, which the perspiration leaves upon our skins. Especially is some means of washing necessary when the free evaporation of perspiration and the free breathing of the skin has been interfered with by clothing which is water-tight or too thick.

Bathing as a Tonic. But bathing is of much greater value than simply as a means of cleansing. Splashing the body with water is the most valuable means that we have of toning up and hardening the skin, and protecting us against the effects of cold. The huge and wonderfully elaborate network of blood vessels that lies in and just under our skins all over our bodies is, from the point of view of circulation, second only in importance to our hearts, and from the point of view of taking cold, and of resisting the attack of disease, one of the most important structures in our entire body. If, by means of daily baths, you keep this mesh of blood vessels in your skin toned up, vigorous, and elastic, and full of red blood, it will do more to keep you in perfect health and vigor than almost any other one thing, except an abundance of food, and plenty of fresh air and exercise. A healthy skin is the best undergarment ever invented.

Right and Wrong Bathing. The best form of bath is either the tub or the shower bath; and the cooler the water, provided that you warm up to it quickly and pleasantly, the greater the tonic effect, the more exhilaration and pleasure you will get out of it, and the more it will harden your skin against cold. But it should never under any circumstances be any cooler than you can readily and pleasantly react, or warm up to, during the bath and afterward. The habit of plunging into a great tub of ice-cold water all winter long, except for people of vigorous constitutions and active habits, may often do quite as much harm as good. Have your bath water just cool enough to give you a slight, pleasant shock, as you plunge into it, or turn it on, so that you will enjoy the glow and sense of exhilaration that follows; and you will get all the good there is out of the cold bath, and none of the harm. By beginning with moderately cool water you will find that you come to enjoy it cooler and cooler. If a bath-room is not at hand, a large wash-bowl of cool, or cold, water into which you can dip your hands and splash well over the upper half of your body every morning, and once or twice a week all over your body, will keep your skin clean and vigorous. If you cannot warm up properly after a cool bath, there is something wrong about your habits of life; and you had better change them, and keep changing them, until you find you can enjoy it. For some delicate children, a quick plunge into, or splash with, very hot water in the morning will give somewhat the same tonic effect as stronger ones can get from cold water.

Warm baths are best taken at night, just before going to bed, though the danger of catching cold after them on account of their "opening up the pores of the skin," has been very greatly exaggerated. They have, however, a relaxing effect upon the skin, and take out an undue amount of the natural oil which nature provides for its oiling and softening, so that, except for special reasons, it is best not to take them oftener than once, or twice, a week.

Soaps and Scrubbing Brushes. As part of the perspiration deposited upon our skins is in the form of a delicate oil, and as this oil may become mixed with dirt, or dust, and form a mixture not readily soluble in water, it is at times advisable to add to the water something that will dissolve oil. The commonest thing used for this purpose is soap, which is a combination of an alkali—most commonly soda, though occasionally potash (lye) is used in the soft soaps—with a fat or an oil. The combination of the two, which we call soap, has been invented for two reasons; one, that it makes a convenient, solid form in which the alkali, needed to dissolve the body oil, can be used in such strength as not to burn or injure the skin; the other, that the fat in the soap will, to some extent, take the place of the natural oil, or fat, which it washes off.

Necessary as soap is, it should be used very moderately. You should never lather and scrub your skin as if it were a kitchen floor, for the reason that, with the dirt, the alkali also washes and dissolves out a considerable amount of the natural oil of the skin, and leaves it harsh and dry. On this account, it is best not to use soap upon the covered portions of the body, and in the full bath, oftener than once or twice a week; and upon the face, oftener than once or twice a day. But the hands may be washed with soap more frequently.

It is also best to avoid the too frequent use of hot water, even upon the hands and face, for the same reason; it takes out too much of the natural oil of the skin, along with the dirt. Unless the dirt be of some infectious, or offensive, character, it is often best to content yourself with washing off just the "big dirt," and wait for the bubbling up of the perspiration through your skin to bring the deeper dirt up to the surface, and wash that off later, in the course of two or three hours.

Soaps to be Avoided. Soaps that lather too quickly and easily should always be avoided, for this shows that they contain an excessive amount of soda or other alkali. It is also best to avoid, or at least be very wary of, any soaps which are dark-colored or heavily perfumed, as these disguises may indicate the presence of decaying, offensive fats, and even of grease extracted from garbage. This is what strong perfumes in soaps are chiefly used for. Beware of all such, and especially of tar soaps, for the black color and the strong odor of tar can cover up any amount of bad quality.

Medicated soaps (soaps containing medicines) are also best let alone. They are only fit to be used on the advice of a doctor. Most of them are out and out humbugs, and make up for their richness in drugs by their poorness in good, pure fat and alkali. Moreover, what may suit one particular diseased condition of the skin is quite as likely to be injurious as helpful to another. Any drug which has the power of curing disease is almost certain to be irritating to a healthy skin; and nothing can be put into a soap beyond pure, sweet fat, or oil, and good soda, which will make it any better, or more wholesome, for a healthy skin. If your skin be red, or itchy, or scaly, or out of condition in any way, go to a doctor and get the appropriate treatment for that particular disease, instead of smearing on the surface of your body some drug of which you know nothing, in the hope of its being the proper thing for the little patch of diseased skin.

Avoid Using Skin Brushes. Scrubbing brushes and skin brushes of all sorts should be used even more sparingly than soap or hot water, for the same reason. Nature did not coat us over with either boards or rubber, but with delicate, velvety, sensitive, living skin worth ten times as much as any sort of leather, bark, rubber, or cloth, for resisting cold, heat, and injuries. It is most important for the health of the skin that we keep that velvety coating unscratched and unbroken. The use of brushes and bristles of all sorts, therefore, should be chiefly restricted to the hair and the finger nails, as for every ounce of dirt that they take out of the skin, they do a pound of damage to it. They scrub off the delicate epidermis, as well as the natural oil in it, and leave it dry and irritated and ready to crack open. Then more dirt gets into the cracks just formed, and more scrubbing with bristles and hot water and soap is indulged in to get it out. This opens the cracks still further, and the next layer of dirt is worked in still deeper. Wash frequently with cold or cool water, occasionally with hot water, and sparingly with soap; and limit the use of brushes to the nails and the hair.

CARE OF THE NAILS

Importance of Clean Nails. On account of their constant use, your hands are brought in contact with dusty or dirty substances in your work and in your play; and it is very easy for some of this dirt, and such germs as it may contain, to lodge in the little chink under the free edge of the nail, between it and the rounded end of the finger. It is of great importance that this nail chink should be kept clean, not only because it looks both ugly and untidy to have the ends of your fingers "in mourning," with black bands across them, but also because the germs lodged under your nails may get onto your food the next time that you eat, and set up irritation and fermentation in your stomach. They may also cause other trouble; for instance, if your collar chafes the back of your neck, and to relieve the itching you rub it a little too hard with your finger, your nail may scratch the skin; and if it be blackened with infectious dirt, this may get into the little scratch and give rise to a boil, or a festering sore.

How to Clean the Nails. This cleaning of the nails, however, must be done carefully and gently; for, if too harsh methods are used, the delicate skin on the under surface of the nail will be torn, the nail will be roughened or split, the dirt will work in just that much deeper next time, and the germs in it may set up inflammations under the nail. For this reason it is best not to use a sharp-pointed knife in cleaning the nails, but a blunt-pointed nail cleaner, such as can be bought for a few cents at any drug store, or such as many pocket-knives are now provided with. It is also best to trim the nails with a file or with scissors, instead of a knife, as the latter may split or tear the nail, or cut down to the quick. Before any of these are used, the nails should be thoroughly softened in warm water, and scrubbed with a moderately stiff nailbrush, such as should be kept on every washstand.

It is also best not to push back the fold of skin at the base of the nails, with instruments of any sort; or indeed, with anything harder than the ball of the thumb or finger. This fold protects the delicate growing part, or root, of the nail; and if it is shoved back too vigorously, the root may become exposed, or even inflamed and infected, and cause one of those extremely irritating little sores known as a "hangnail."

DISEASES AND DISTURBANCES OF THE SKIN

Their Chief Causes. Skin troubles are of two main kinds according to their cause: internal, due to the irritation of waste-poisons, or toxins, in the blood; and external, from direct injury or irritation of the skin from without.

The latter are often due to the wearing of too tight or too heavy clothing, or the failure properly to wash, cleanse, and ventilate the skin. Some of the lesser disturbances come from the chafing of collars, wristlets, and belts, and are, of course, relieved by loosening the clothing or substituting soft, comfortable cotton for rasping flannels. Others come from the use of too strong soaps, or the too frequent use of hot water, or too vigorous scrubbing of the skin, and these can be relieved by the avoidance of their cause.

Sunburn and Freckles and how to Cure Them. Upon the hands and face, sunburn and freckles may occur from exposure to the weather. They are not caused necessarily by exposure to direct sunlight; as the bright light and the cold air out of doors, also, will produce this irritating effect upon the skin.

The best way to cure sunburn is to bathe in cool water, take a night's rest, then go out the next day, and the day after, and take another dose of exposure, keeping this up until your face is hardened to stand a reasonable amount of sun. If you are in proper condition, neither your face nor your hands will sunburn uncomfortably. If they do, except under extreme exposure, it is a sign that you have not been living out of doors enough.

The various face-washes and creams and dusting powders which are used for the relief of sunburn, while they may, if mild enough, make the face feel somewhat more comfortable for a little time, owe most of their virtues to the fact that they are generally used at bedtime and then get the credit for the cure which nature works while you are asleep. If you should buy them, and keep them on your dressing-table unopened, where you could see them before you went to bed, you would in nine cases out of ten be just as much better in the morning as if you had used them.

The only harm done by freckles is to your vanity. They and sunburn both, in fact, are protective actions on nature's part, filling the skin with coloring matter, or pigment, so as to protect it, and the tissues below, from the irritating effects of the strong rays of light.

A like deposit of pigment, in greater amounts, in the skins of races who live in or near the tropics, gives rise to the characteristic coloring of the black, brown, and yellow races. The pigment, or coloring matter, is of exactly the same kind in all, from the negro to the white. The brown race having a little less of it than the negro, the yellow race a little less yet, and the white least of all, though there is some of it in even the whitest of skins.

Real Skin Diseases. Most of the serious and lasting diseases of the skin are caused by the attack of germs. Perfect cleanliness and ventilation are the best protection against them all; but if you should be unfortunate enough to catch one of these diseases, your doctor will be able to give you the mild germicide or antiseptic that will kill the particular germ that may have lodged upon your skin.

The commonest form of inflammation of the skin is called eczema, and eight-tenths of all eczemas are due to some mild germ, and can be cured by the appropriate poison for it.

Other diseases, particularly of the scalp, such as ringworm and dandruff, are due to other forms of vegetable germs, and may be cured by their proper poisons; while others, such as the so-called "prairie itch" (scabies), and lice in the hair, are due to the presence of tiny animal parasites.

The Hookworm. Another disease which enters through the skin is the now famous hookworm, or blood-sucking parasite, which has been found to be so common in tropical regions and in our Southern States. This parasite has the curious habit of attaching itself by hooks surrounding its mouth (which gave it its name), to the lining of the human intestine, particularly its upper third. There it swings, and lives by sucking the blood of its victim. When the worm has once attached itself in the intestine, it may live for from five to fifteen years. All this time it is constantly laying eggs; and these eggs, which are so tiny that they have to be put under a microscope to be seen, pass out in the feces; and if they are not deposited in a proper water closet, or deep vault, but scattered about upon the surface of the soil, the eggs quickly hatch into tiny, little wriggling worms called larvæ, which are still scarcely large enough to be seen with the naked eye.

These larvæ live in the soil; and, when it is wet and muddy, they get up between the toes of boys and girls who are going barefoot, burrow their way in through the skin, and produce a severe itching inflammation of the skin of the feet, known as "ground-itch," "toe-itch" or "dew-itch." When they have worked their way through the skin, they bore on into a blood vessel, are carried to the heart, pumped by the heart into the lungs, and there again work their way out of the blood vessels into the bronchial, or air tubes, crawl up these through the windpipe and voice organ into the throat, are swallowed into the stomach, and from there pass on into the upper intestine to attach themselves for their blood-sucking life. If they are sufficiently numerous, their victim becomes thin, weak, and bloodless, with pale, puffy skin, and shortness of breath; he is easily tired on the least exertion, and ready to fall a victim to any disease, like tuberculosis, pneumonia, or typhoid, that may happen to attack him.

Their spread can be absolutely prevented either by the strict use of toilets or deep vaults, thus preventing the deposit of feces anywhere upon the surface of the ground; or by the constant wearing of shoes or sandals, thus preventing the larvæ from attacking the feet and working their way through the skin and body into the intestine.

Fortunately, the disease is as curable as it is common, and two doses of a proper germicide, with a day in bed, and a laxative, will promptly cure it except in the worst cases.

The Rashes of Measles, Scarlet Fever, etc. Many of the infectious fevers, such as measles, scarlet fever, chicken-pox, and smallpox, are attended by rashes, or eruptions, upon the surface of the skin, due to a special gathering or accumulation of the particular germs causing each disease, just under the skin. When the skin sheds, or flakes off, after the illness, the germs are shed in the scales and float, or are carried about, and thus spread the disease to others.

These rashes or eruptions are not dangerous in themselves, though often very uncomfortable, but help us to recognize the disease; they probably show us the sort of thing that is going on in the deeper parts of the body. If you imagine that your throat and bronchial tubes and lungs are peppered as full of the disease spots as your skin is, in measles and in scarlet fever, you will readily understand why your throat is so sore and why you have so much tickling and coughing.

The Health of the Scalp and Hair. The scalp, being covered by hair, does not perspire so freely as the rest of the skin of the body; but a considerable amount of oily waste matter is poured out on it, and the surface of its skin scales off in exactly the same way as does the rest of the body. If this accumulation of tiny scales and grease is not properly brushed out, it forms an excellent seed-bed for some of the milder kinds of germs that attack the skin; and a scurfy, itchy condition of the scalp is set up, known as dandruff.

The best way to keep the scalp clean of these accumulations of greasy scales is by vigorous and regular brushing with a moderately stiff, but flexible, bristle brush. Wire brushes should not be used, as the wires scratch and irritate the delicate scalp and do more harm than good. If you watch a groom brushing and currying the coat of a thoroughbred horse, you will get a fair idea of hew you ought to treat your own scalp at least twice a day, night and morning.

If this currying of the hair be thoroughly done, and the head washed with soap and hot water about once a week for short hair and twice a month for long hair, most of the dangers of dandruff and of other infections of the scalp will be avoided. One thing to be remembered is, don't brush too hard or too deep. There is an old saying and a good one, "You can't brush the scalp too little, or the hair too much."

Wetting the hair for the purpose of "slicking" it or combing it, is about as bad a thing as could be done; for the moisture sets up a sort of rancid fermentation in the natural oil of the scalp, giving the well-known sour smell to hair that is combed instead of brushed, and furnishing a splendid soil for germs and bugs of all sorts to breed in. There is no objection to boys' and men's wetting their hair in cold water as often as they wish, provided that they rub it thoroughly dry afterward and give it a brisk currying with the brush.

Hair oils and greases of all sorts are sanitary nuisances, and mere half-civilized and lazy substitutes for proper brushing and washing. There is no drug known to medicine which will cause hair to grow, or make it thicker or curlier. All "hair tonics" claiming to do this are frauds.

Corns, Calluses, and Warts. Our skin not only made our hair, teeth, and nails, but still retains in every part a trace of its nail-making powers, so that under pressure or irritation, it can thicken up into a heavy leather-like substance which we call callus. This is naturally and healthfully present in the soles of the feet and the palms of the hands. Savage, or barbarous, races who wear no shoes get the skin of their soles thickened into a regular human leather, almost half an inch thick, and as tough as rawhide. A somewhat similar condition develops in the palms of the hands of those who work hard with spades, axes, or other tools.

Any good process carried to excess becomes bad, and this is true of this power of callus formation in the skin; for parts of it which are under constant pressure, like the surface of the toes inside the shoe, and particularly of the outside toes, the little and the big toe, develop under that pressure patches of thickened, horny skin, which we call corns. These patches start to grow into cone-shaped projections or buttons; but being prevented from growing outward by the pressure of the shoe, they turn upon themselves and burrow into the skin itself, and we get the well-known ingrowing corn.

If there is anything in the human body which we ought to be thoroughly ashamed of, it is corns; for they are caused by our own vanity, and nothing else, in cramping our feet into shoes one or two sizes too small for them. There are a number of things that can be done to relieve the discomfort of the corn, but the only sure way is to remove its cause, namely, the tight shoe.

Under other kinds of irritation, the skin has the power of growing curious little button-like buds, or projections, which we call warts. These are commonest in childhood, and generally disappear at about twelve or fifteen years of age, when we no longer delight in dirt, and glory in mud pies.

They can be produced upon the hands of grown men and women by irritating fluids and substances, such as wet sugar in the case of bakers and confectioners, and various color-stains in dye works. They seldom last for more than a few months, and usually narrow at their base and drop off, when the particular irritation that caused them ceases. On this account it is seldom worth while to try to remove them by burning with acids or cutting them off; and it is best not to pick at, or irritate, or scratch them too much.

CHAPTER XVII

This sounds rather complicated; but is interesting, because it shows how much of a "mind of their own" the different organs and stuffs in our bodies have, or what, in scientific language, we call "power of selection." The skin glands pick out of the blood those waste substances which they are able to get rid of. The kidneys pick out another class of waste substances, which they are best able to deal with; while the liver which is the most important of all, attacks almost every kind of waste brought to it by the blood, and prepares it for disposal by the intestines, skin, and kidneys.

The Liver. The liver has a size to match its importance. It is the largest and heaviest gland, or organ, in the body, and weighs about three pounds, a little more than the brain. It buds off from the food tube just below the stomach, so that its waste tube, the bile duct—about the size of a goose quill—opens into the upper part of the intestine.

The main work of the liver is to receive the blood from all over the body and to act upon its waste substances, burning them up so that they can be taken up, and got rid of, by the glands of the skin and the kidneys. In the process it very frequently changes these waste substances from poisonous into harmless forms; and even when disease germs get into the body and infect it, the poisons, or toxins, which they pour into the blood are carried to the liver and there usually burned up, or turned into harmless substances.

The liver is, therefore, to be regarded as a great poison filter for the entire body. So long as it can deal with the poisons as fast as they are formed, either by the body itself, or in the food, or by disease germs, the body is safe and will remain healthy. But if the poisons come faster than the liver can deal with them, as, for instance, when we have eaten tainted meat or spoiled fruit, or have drunk alcohol, they begin to poison our nerves and muscles, and we become, as we say, "bilious." Our head aches, our tongue becomes coated, we have a bad taste in the mouth, we lose our appetite and feel stupid, dull, and feverish.

Such waste materials as the liver cannot burn down so that the kidneys and skin can handle them, it pours out through its duct into the intestine as the bile. The bile is a yellowish-brown fluid, which assists the pancreatic juice in the digestion of the food, and helps to dissolve the fats eaten, but is chiefly a waste product. It turns green when it has been acted upon by acids, or exposed to the air. So that the bile which you throw up when you are very sick at your stomach, is green because it has been acted upon by your gastric juice.

As you will remember, the blood which comes from the stomach and bowels is carried by the portal vein to the liver first and, through that, to the heart, instead of going directly to the heart, as all the other impure blood in the body does. This is owing, in part, to the fact that this blood, being full of substances freshly taken or made from the food, is very likely to contain poisons; indeed, as a matter of fact, blood taken from these veins on its way to the liver, and injected directly into the blood vessels of an animal, acts like a mild poison.

In part, however, this blood goes first to the liver, because the liver, besides being a great blood purifier, is a "blood-maker" in the sense that it changes raw food-stuffs in the blood from the intestines into forms which are more suitable for use by the brain, the muscles, and the other tissues of the body. Some of the sugars, for instance, the liver turns into a kind of animal starch (glycogen), which it stores away in its own cells. It also turns both sugars and proteins in the portal blood into fat, part of which it pours into the blood, and part of which it stores away also in its own cells. Thus the liver owes its great size partly to the large amount of blood-purifying, filtering, and poison-destroying work which it has to do, and partly to its acting as a storehouse of starch and fat, which the body can readily draw upon as it needs them.

As all poisons formed in, or entering, the body are brought to the liver for destruction, it is in an extremely exposed position, and very liable to break down under the attack of these poisons, whether of infectious diseases, or chloroform, or alcohol, or those formed by putrefaction in the stomach and intestines. This is why those who have lived long in the tropics and suffered from malaria, dysentery, and other infectious diseases, and those who drink too much alcohol, or have chronic indigestion, or dyspepsia, are likely to have swollen and inflamed livers.

The Gall Bladder. The liver has on its under side a little pear-shaped pouch called the gall bladder, in which the bile is stored before it is poured into the bowel. If this becomes inflamed by disease germs, or their poisons, in the blood, little hard masses will form inside it, usually about the size of a grain of corn, known as gall stones. So long as they stay in the gall bladder, they give little trouble, but if they start to pass out through the narrow bile duct into the intestine, they cause severe attacks of pain, known as "gall-stone colic," and, by blocking up the duct, may dam up the flow of the bile, force it back into the blood again, and stain all our tissues, including our skin and our eyes, yellow; and then we say we are jaundiced. Jaundice may also be caused by colds or other mild infections which attack the liver and bile ducts and clog the proper flow of the bile.

The Kidneys. The kidneys are another form of blood-filter, which deal chiefly with waste stuffs in the blood left from the proteins, or Meats, of our food—meat, fish, milk, cheese, bread, peas, beans, etc. These waste-stuffs, called urea and urates, are formed in the liver and brought in the blood to the kidneys. These lie on either side of the backbone, opposite the small of the back, their lower ends being level with the highest point of the hip-bones, nearly six inches higher than they are usually supposed to be. When you think you have a "pain across the kidneys," it is usually a pain in the muscles of the back much lower down, and has nothing to do with the kidneys at all.

A very large artery carries the blood from the aorta to each side of the kidney, and a large vein carries the purified blood back to the vena cava and heart. Two smaller tubes about the size of a crow quill, the waste pipes of the kidneys (the ureters), carry the water containing urea and other waste substances strained out by the kidneys and called urine, down into a large pouch, the bladder, to be stored there until it can be got rid of.

The kidneys then are big filter-glands. They, like the lungs, are made up of a mesh, or network, of thousands of tiny tubes of two kinds, one set of tubes being blood vessels, and the other set the tiny branches of the kidney tubes which finally run together to form the ureters. The urine filters through from the spongy mesh of blood tubes (capillaries) into the kidney tubes and is poured out through the ureters. It is very important that the urine should be discharged as fast as it fills the bladder, that is, about once every three hours during the day. Nothing should be allowed to interfere with this; and whenever nature tells you that the bladder is full, it should be emptied promptly, or the poisons which nature is trying to get rid of in the urine may get back into the blood and cause serious trouble.

Diseases of the Kidneys. Naturally, the kidneys, working all the time and pouring out, as they do every day, from three to four pints of the liquid waste called urine, are subject to numerous diseases and disturbances. One of the common causes of these is failure to keep the skin thoroughly clean and healthy, as perspiration is of somewhat the same character as the urine; and if it be checked, it throws an extra amount of work upon the kidneys.

Another most important thing to keep the kidneys working well is to drink plenty of water, at least six or eight glasses a day, as well as to eat plenty of fresh green vegetables and fresh fruits, which, as we have seen, are eighty per cent water. Remember, we are a walking aquarium, and all our cells must be kept flooded with and soaked in water in order to be healthy. If the blood becomes overloaded with poisons, so much work may be thrown upon the kidneys that they will become inflamed and diseased and cannot form the urine properly; and then poisons accumulate in the system and finally produce serious illness and even death.

It was at one time believed that eating too much of certain kinds of foods, particularly those that leave much nitrogenous waste in the body, such as meat and fish, could produce a diseased condition of the kidneys, known as Bright's Disease; but we have found that the larger part of such cases are due to the attack of the germs of infectious diseases, particularly scarlet and typhoid fevers, tuberculosis, and colds. The popular impression that colds from wet feet or long drives in winter may "settle in the kidneys" is wrong, except in so far as those colds are caused by infectious germs.

Another cause of disturbance and permanent damage to the kidneys is the habitual use of alcohol. Even though this may be taken in only moderate amounts, the constant soaking of the tissues with even small amounts of alcohol may be most harmful to the kidneys, as well as to the liver.

CHAPTER XVIII

The astonishing variety of movements which muscles can make is due to the fact that they have the power when stirred up, or stimulated, of changing their shape. As most of the muscle substance is arranged in bands, this change of shape on the part of the tiny cells that make up the band means that the band grows thicker and at the same time shorter,—just as a stretched rubber band does when it slackens,—so that it pulls nearer together the bones or other structures to which it is fastened at each end by fibrous cords called tendons, or sinews. This shortening of the muscle band is known as contraction.

When you wish, for instance, to lift your hand toward your face, you unconsciously send a message from your brain down the nerve cables in your spinal cord, out through the nerve-wires of your neck and shoulder, to the big biceps muscle on the front of your upper arm. This muscle then contracts, or shortens, and pulls up the forearm and hand, by bending the elbow joint. Just in proportion as the muscle becomes shorter, it becomes thicker in the middle; and this you can readily prove by grasping it lightly with your fingers when it contracts, and feeling it bulge.[22]

The food tube is surrounded with muscles, as you will remember, for moving the food along it, or churning it. These internal muscles, requiring only the presence of food to cause them to act, and not needing attention on the part of the brain or the will, are known as the involuntary ("without the will") muscles.

The great group of the voluntary, or bone-moving muscles, which move "with the will" and are under our direct control, may be divided roughly into two divisions—those that move the trunk, or body proper, and run, for the most part, lengthwise of it; and those that move the limbs.

On the body, they may be divided into two great sheets—one running up the front, and the other up the back. When those running up the front of the body contract, they naturally bend the back, and pull the head and shoulders forward and downward. Or, as when you spring up and catch the branch of a tree or a horizontal bar with your hands, these same muscles will pull the lower part of the body and legs upward, so that you can climb into the tree.

The largest and thickest bands of these front body muscles are found over the abdomen, or stomach, where you can feel them thicken and harden when you bend your body forward and pull with your arms, as in hauling on a rope. By their pressure upon the intestines, they give the bowels valuable support, assist in their movements, and help the circulation of the blood through them; so that it is of considerable importance to keep this entire group of muscles well toned up by exercises, such as swinging your arms back over your head, and then down between your legs; bending the head and shoulders backward and forward; swinging the legs up over the body, either when hanging from a bar or lying on your back. Proper exercising and toning up of these muscles will often cure constipation and dyspepsia, by their influence upon the bowels and stomach, and also keep one from taking on fat around the waist too rapidly.

On the back of the body, the muscle-sheet has grown into great, thick ropes of muscle on each side of the backbone, which you can feel hardening and softening in the small of the back, when you stoop down or lift weights. These are the muscles that hold the body erect, and keep the back straight when you stand, and are the largest and hardest working group of muscles in the body. Every minute that you sit, or stand, they are at work; and that is why they so often get tired out, and ache, and you say you have "a backache." They have to work harder to keep you erect or upright when you are standing perfectly still than when you walk or run, so that standing perfectly still is the hardest work you can do. Next to standing still, the hardest thing is to sit still, as you probably have found out. If it were not for these great muscles of the back and abdomen, we should double up like a jack-knife, either forward or backward, when we tried to stand up. It is not our skeleton that keeps us stiff or erect, but our muscles.

If you want to keep straight and erect, and thus have a good carriage, you must keep these great body muscles well trained and exercised by swinging movements, such as bending the back forward, standing with your feet apart and then swinging your head and shoulders down and between your legs; or, with your heels together, swinging your hands down till the fingers touch the ground; or by the different exercises that either bend your back, or hold it stiff and erect. Swinging from a bar, rowing, digging with a spade, chopping or sawing wood, dancing, rope-skipping, ball-playing, hop-scotch, and wrestling, all develop these muscles finely and are good for both boys and girls.

Other strands of these muscles branch out to fasten themselves to the shoulder blades and shoulders, where they help to draw the arm back as for a blow, pull the shoulders into position when you stand upright, or, when you have leaned forward and grasped something with the hand, help to pull up the arm and lift it from the ground. These muscles are quite important in holding the shoulders back and giving a good shape to the chest and good carriage of the upper part of the body and head. They are called into play in all exercises like striking, batting, tennis-playing, ball-throwing, swinging, shoveling, swimming, as well as in pulling, in lifting weights, in swinging an axe or handling a broom.