John Harvey Kellogg
First Book in Physiology and Hygiene
CHAPTER XV
THE SKIN AND WHAT IT DOES
1. The Skin.—The skin is the covering of the body. It fits so exactly that it has the precise shape of the body, like a closely fitting garment. If you will take up a little fold of the skin you will see that it can be stretched like a piece of india-rubber. Like rubber, when it is released it quickly contracts and appears as before.
2. The Bark of Trees.—Did you ever peel the bark off of a young tree? If so, you have noticed that there were really two barks, an outer bark, as thin as paper, through which you could almost see, and an inner and much thicker bark, which lay next to the wood of the tree. You can peel the outer bark off without doing the tree much harm. Indeed, if you will notice some of the fruit or shade trees in the yard, at home, you will see that the outer bark of the tree peels itself off, a little at a time, and that new bark grows in its place. If you tear off the inner bark, however, it will injure the tree. It will make it bleed, or cause the sap to run. The sap is the blood of the tree. The bark is the skin of the tree. When the bare place heals over, an ugly scar will be left.
3. The Cuticle.—Our bodies, like trees, have two skins, or really one skin with an outer and an inner layer. When a person burns himself so as to make a blister, the outer skin, called the cuticle, is separated from the inner by a quantity of water or serum poured out from the blood. This causes the blister to rise above the surrounding skin. If you puncture the blister the water runs out. Now we may easily remove the cuticle and examine it. The cuticle, we shall find, looks very much like the skin which lines the inside of an egg-shell, and it is almost as thin.
4. The cuticle is very thin in most parts of the body, but in some places, as the palms of the hands and the soles of the feet, it is quite thick. This is because these parts of the skin come in contact with objects in such a way as to be liable to injury if not thus protected. The cuticle has no blood-vessels and very few nerves. With a fine needle and thread you can easily take a stitch in it without making it bleed or causing any pain.
5. The Pigment.—The under side of the cuticle is colored by little particles of pigment or coloring matter. The color of this pigment differs in different races. In the negro, the color of the pigment is black. In some races the pigment is brown. In white persons there is very little pigment, and in some persons, called albinos, there is none at all.
6. The Inner or True Skin.—The inner skin, like the inner bark of a tree, is much thicker than the outer skin. It is much more important, and for this reason is sometimes called the true skin. It contains nerves and blood-vessels.
SKIN OF PALM OF HAND MAGNIFIED.
7. The Sweat Glands.—If you look at the palm of the hand you will see many coarse lines, and by looking much closer you will see that the palm is completely covered with very fine ridges and furrows. Now, if you examine these ridges with a magnifying-glass, you will find arranged along each ridge a number of little dark spots. Each of these points is the mouth of a very small tube. This is called a sweat duct. These ducts run down through both the outer and inner layers of the skin. At the under side of the true skin the end of the tube is rolled up in a coil, as you can see by looking at the illustration on the following page. The coiled parts of the tubes are called sweat glands, because they separate from the blood the fluid which we call sweat or perspiration.
8. The Oil Glands.—There are other little glands in the skin which make fat or oil. The oil is poured out upon the skin to keep it soft and smooth.
THE STRUCTURE OF THE SKIN.
9. The Hair.—There are some curious little pockets in the skin. Out of each of these pockets grows a hair. On some parts of the body the hairs are coarse and long; on other parts they are fine and short.
10. Many of the ducts leading from the oil glands open into the pockets or pouches from which the hairs grow. The oil makes the hair soft and glossy. Nature has thus provided an excellent means for oiling the hair.
11. The hair is chiefly useful as a protection. It is also an ornament.
12. The Nails.—The nails of the fingers and the toes grow out of little pockets in the skin just as the hairs do. Both the hair and the nails are really parts of the outer skin, which is curiously changed and hardened. The nails lie upon the surface of the true skin and grow from the under side as well as from the little fold of skin at the root of the nail. They are made to give firmness and protection to the ends of the fingers and toes. The nails of the fingers are also useful in picking up small objects and in many other ways.
13. Uses of the Skin.—The skin is useful in several ways:
(1) It Removes Waste.—The sweat glands and ducts are constantly at work removing from the blood particles which have been worn out and can be of no further use. If we get very warm, or if we run or work very hard, the skin becomes wet with sweat. In a little while, if we stop to rest, the sweat is all gone. What becomes of it? You say it dries up, which means that it has passed off into the air. Sweating is going on all the time, but we do not sweat so much when we are quiet and are not too warm, and so the sweat dries up as fast as it is produced, and we do not see it. Nearly a quart of sweat escapes from the skin daily.
(2) Breathing through the Skin.—We breathe to a slight extent through the skin. There are some lower animals which breathe with their skins altogether. A frog can breathe with its skin so well that it can live for some time after its lungs have been removed. Breathing is an important part of the work of the skin, and we should be careful, by keeping it clean and healthy, to give it a good chance to breathe all that it can.
(3) The Skin Absorbs.—The skin absorbs many substances which come in contact with it, and hence should be kept clean. If the foul substances which are removed in the sweat are allowed to remain upon the skin, they may be taken back into the system and thus do much harm.
(4) The Skin has Feeling.—When anything touches the skin we know it by the feeling. We can tell a great many things about objects by feeling of them. If we happen to stick a pin into the skin we feel pain. We are also able to tell the difference between things which are hot and those which are cold. Thus the sense of feeling which the skin has is very useful to us.
(5) The Skin Protects the Body.—The skin is a natural clothing which protects us much better than any other kind of clothing could. It is so soft and pliable that it cannot hurt the most delicate part which it covers, yet it is very strong and tough.
SUMMARY
1. The skin is the covering of the body. It has two layers, the outer, called the cuticle, and the inner, called the true skin.
2. A substance called pigment is found between the two skins. This gives the skin its color.
3. The true skin has blood-vessels and nerves, but the cuticle has no blood-vessels and very few nerves.
4. In the true skin are glands which produce sweat, and others which make fat, or oil.
5. The nails are really a part of the skin. They are firm and hard, and protect the ends of the fingers and the toes.
6. The hair grows from the true skin. The hair is made soft and glossy by oil from the oil glands of the skin.
7. The skin is a very useful organ. It removes waste matters, it breathes, it absorbs, it has feeling, and it protects the body.
CHAPTER XVI
HOW TO TAKE CARE OF THE SKIN
1. Uses of the Pores of the Skin.—Many years ago, at a great celebration, a little boy was covered all over with varnish and gold leaf, so as to make him represent an angel. The little gilded boy looked very pretty for a short time, but soon he became very sick, and in a few hours he was dead. Can you guess what made him die? He died because the pores of his skin were stopped up, and the sweat glands could not carry off the poisonous matter from his body.
2. Cleanliness.—Did you ever know of a boy who had his skin varnished? Not exactly, perhaps; but there are many boys who do not have their skins washed as often as they ought to be, and the sweat and oil and dead scales form a sort of varnish which stops up the little ducts and prevents the air from getting to the skin, almost as much as a coat of varnish would do.
3. The Sweat Glands.—The sweat glands and ducts are like little sewers, made to carry away some of the impurities of the body. There are so many of them that, if they were all put together, they would make a tube two or three miles long. These little sewers drain off almost a quart of impurities in the form of sweat every day. So you see that it is very important for the skin to be kept clean and healthy.
4. Bathing.—A bird takes a bath every day. Dogs and many other animals like to go into the water to bathe. Some of you have seen a great elephant take a bath by showering the water over himself with his trunk. To keep the skin healthy we should bathe frequently.
5. When we take a bath for cleanliness it is necessary to use a little soap, so as to remove the oil which is mixed up with the dry sweat, dead scales, and dirt which may have become attached to the skin.
6. It is not well to take hot baths very often, as they have a tendency to make the skin too sensitive. Bathing in cool water hardens the skin, and renders one less likely to take cold.
7. The Clothing.—The skin should be protected by proper clothing, but it is not well to wear more than is necessary, as it makes the skin so sensitive that one is liable to take cold.
8. The Proper Temperature of Rooms.—It is also very unwise for a person to keep the rooms in which he lives too warm, and to stay too much in-doors, as it makes him very liable to take cold when he goes out-of-doors. One who is out of doors in all kinds of weather seldom takes cold.
9. Care of the Hair and the Nails.—The scalp should be kept clean by thorough and frequent washing and daily brushing. Hair oils are seldom needed. If the skin of the head is kept in a healthy condition, the hair requires no oil.
10. The habit of biting and picking the fingernails is a very unpleasant one, and keeps the nails in a broken and unhealthy condition. The nails should be carefully trimmed with a sharp knife or a pair of scissors.
11. Effects of Narcotics and Stimulants upon the Skin.—Alcohol, tobacco, opium, and all other narcotics and stimulants have a bad effect upon the skin. Alcohol often causes the skin to become red and blotched, and tobacco gives it a dingy and unhealthy appearance.
SUMMARY
1. If the pores of the skin are closed, a person will die.
2. We should bathe often enough to keep the skin clean.
3. We should not keep our rooms too warm, and should avoid wearing too much clothing.
4. Alcohol, tobacco, and other stimulants and narcotics injure the skin.
CHAPTER XVII
THE KIDNEYS AND THEIR WORK
1. The Kidneys.—The kidneys are among the most important organs of the body. They are in the cavity of the abdomen, near the back-bone, up under the lower border of the ribs. Perhaps you have seen the kidneys of a sheep or a hog. If you have, you know very nearly how the kidneys of our own bodies appear.
KIDNEY.
2. The Work of the Kidneys.—The work of the kidneys is to separate from the blood certain very poisonous substances, which would soon cause our death if they were not removed. It is very important to keep these useful organs in good health, because a person is certain to die very soon when the kidneys are in any way seriously injured.
3. How to Keep the Kidneys Healthy.—One way of keeping the kidneys in good health is to drink plenty of pure water, and to avoid eating too much meat and rich food. Pepper, mustard, and other hot sauces are very harmful to the kidneys.
4. Importance of Keeping the Skin Clean.—The work of the kidneys is very similar to that of the skin; and when the skin does not do its full duty, the kidneys have to do more than they should, and hence are likely to become diseased. For this reason, persons who allow their skins to become inactive by neglecting to bathe frequently are apt to have disease of the kidneys.
5. Effects of Alcohol and Tobacco upon the Kidneys.—A piece of beef placed in alcohol soon becomes dry and hard, and shrivels up as though it had been burned. The effect upon the kidneys of drinking strong liquor is almost the same. Beer and hard cider also do the kidneys harm, sometimes producing incurable disease of these important organs.
SUMMARY
1. The kidneys somewhat resemble the skin in their structure and in their work.
2. The kidneys remove from the blood some poisonous substances.
3. To keep the kidneys healthy we should drink plenty of water, avoid irritating foods and drinks, and keep the skin in health by proper bathing.
4. The drinking of strong liquors often causes incurable disease of the kidneys.
CHAPTER XVIII
OUR BONES AND THEIR USES
1. The Bones.—In an earlier chapter we learned something about the bones. This we must try to recall. You will remember that we called the bones the framework of the body, just as the timbers which are first put up in building a house are called its frame.
2. The Skeleton.—All the bones together make up the skeleton. (See page 95.) There are about two hundred bones in all. They are of many different shapes. They vary in size from the little bones of the ear, which are the smallest, to the upper bone of the leg, which is the largest in the body.
3. The skeleton is divided into four parts: the skull, the trunk, the arms, and the legs. We must learn something more about the bones of each part.
4. The Skull.—The skull is somewhat like a shell. It is made of a number of bones joined together in such a way as to leave a hollow place inside to hold the brain. The front part of the skull forms the framework of the face and the jaws. In each ear there are three curious little bones, which aid us in hearing.
5. The Trunk.—The bones of the trunk are, the ribs, the breast-bone, the pelvis, and the back-bone. The bones of the trunk form a framework to support and protect the various organs within its cavities.
6. The Ribs.—There are twelve ribs on each side. The ribs join the back-bone at the back. They are connected by cartilage to the breast-bone in front. They look somewhat like the hoops of a barrel. With the breast-bone and the back-bone they form a bony cage to contain and protect the heart and the lungs.
7. The Pelvis.—The pelvis is at the lower part of the trunk. It is formed by three bones, closely joined together. The large bones at either side are called the hip-bones. Each hip-bone contains a deep round cavity in which the upper end of the thigh-bone rests.
8. The Back-bone.—The back-bone, or spinal column, is made up of twenty-four small bones, joined together in such a way that the whole can be bent in various directions. The skull rests upon the upper end of the spinal column. The lower end of the back-bone forms a part of the pelvis.
SKELETON OF A MAN.
9. The Spinal Canal.—Each of the separate bones that make up the back-bone has an opening through it, and the bones are so arranged, one above another, that the openings make a sort of canal in the back-bone. By the connection of the spinal column to the head, this canal opens into the cavity of the skull. Through this canal there passes a peculiar substance called the spinal cord, of which we shall learn more at another time.
10. The Arms.—Each of the arms has five bones, besides the small bones of the hand. They are the collar-bone, which connects the shoulder to the breast-bone, the shoulder-blade, at the back of the shoulders, the upper arm-bone, between the shoulder and the elbow, and the two lower arm-bones, between the elbow and the wrist. There are eight little bones in the wrist, five in that part of the hand next to the wrist, and fourteen in the fingers and thumb.
11. The Legs.—The bones of the leg are the thigh or upper leg-bone, the knee-pan or knee-cap, which covers the front of the knee, the two bones of the lower leg, the heel-bone and six other bones in the ankle, five bones in that part of the foot next to the ankle, and fourteen bones in the toes.
12. Use of the Bones.—The skeleton is not only necessary as a framework for the body, but it is useful in other ways. Some of the bones, as the skull, protect delicate parts. The brain is so soft and delicate that it would be very unsafe without its solid bony covering. The spinal cord also needs the protection which it finds in the strong but flexible back-bone. The bones help to move our hands and arms, and assist us in walking.
13. The Joints.—The places where two or more bones are fastened together are called joints. Some joints we can move very freely, as those of the shoulder and the hip. Others have no motion at all, as those of the bones of the skull.
14. Cartilage.—The ends of bones which come together to form a joint are covered with a smooth, tough substance, which protects the bone from wear. This is called gristle or cartilage. You have, no doubt, seen the gristle on the end of a "soup-bone" or on one of the bones of a "joint of beef."
15. The joint contains a fluid to oil it, so that the ends of the bones move upon each other very easily. If the joints were dry, every movement of the body would be very difficult and painful.
16. The bones are held together at the joints by means of strong bands called ligaments.
17. How the Bones are Made.—The bones are not so solid as they seem to be. The outside of most bones is much harder and firmer than the inside. Long bones, like those of the arms and the legs, are hollow. The hollow space is filled with marrow, in which are the blood-vessels which nourish the bone.
18. An Experiment.—If you will weigh a piece of bone, then burn it in the fire for several hours, and then weigh it again, you will find that it has lost about one third of its weight. You will also notice that it has become brittle, and that it seems like chalk.
19. Why the Bones are Brittle.—The hard, brittle portion of a bone which is left after it has been burned contains a good deal of chalk and other earthy substances, sometimes called bone-earth. It is this which makes the bones so hard and firm that they do not bend by the weight of the body. When we are young, the bones have less of this bone-earth, and so they bend easily, and readily get out of shape. When we get old, they contain so much bone-earth that they become more brittle, and often break very easily.
20. A person's height depends upon the length of his bones. The use of alcohol and tobacco by a growing boy has a tendency to stunt the growth of his bones, so that they do not develop as they should.
SUMMARY
1. There are about two hundred bones in the body.
2. All together they are called the skeleton.
3. The skeleton is divided as follows:
a. The skull.
4. The bones are useful for support, protection, and motion.
5. The place where two bones join is called a joint.
6. The tough substance which covers the ends of many bones is called cartilage or gristle.
7. The joints are enabled to work easily by the aid of a fluid secreted for that purpose.
8. The ends of the bones are held together in a joint by means of ligaments.
9. Bones are about two thirds earthy matter and one third animal matter.
10. The use of alcohol and tobacco may prevent proper development of the bones.
CHAPTER XIX
HOW TO KEEP THE BONES HEALTHY
1. Composition of the Bones.—Our bones, like the rest of our bodies, are made of what we eat. If our food does not contain enough of the substances which are needed to make healthy bone, the bones will become unhealthy. They may be too soft and become bent or otherwise misshapen. This is one of the reasons why bread made from the whole grain is so much more healthful than that made from very fine white flour. In making fine white flour the miller takes out the very best part of the grain, just what is needed to make strong and healthy bones. Oatmeal is a very good food for making healthy bones.
2. Bones of Children.—Sometimes little children try to walk before the bones have become hard enough to support the weight of the body. This causes the legs to become crooked. In some countries young children work in factories and at various trades. This is wrong, because it dwarfs their growth, and makes them puny and sickly.
3. Improper Positions.—The bones are so soft and flexible when we are young that they are very easily bent out of shape if we allow ourselves to take improper positions in sitting, lying, or standing. This is the way in which flat and hollow chests, uneven shoulders, curved spines, and many other deformities are caused.
IMPROPER POSITION.
4. In sitting, standing, and walking, we should always take care to keep the shoulders well back and the chest well expanded, so that we may not grow misshapen and deformed. Many boys and girls have ugly curves in their backbones which have been caused by sitting at high desks with one elbow on the desk, thus raising the shoulder of that side so high that the spine becomes crooked. The illustrations on this and the following page show good and bad positions and also the effects of bad positions.
PROPER POSITION.
5. Seats and Desks.—The seats and desks of school-children should be of proper height. The seats should be low enough to allow the feet to rest easily upon the floor, but not too low. The desk should be of such a height that, in writing, one shoulder will not be raised above the other. If a young person bends the body forward, he will, after a time, become round-shouldered and his chest will become so flattened that the lungs cannot be well expanded.
DESK TOO HIGH.
6. Standing on one foot, sitting bent forward when reading or at work, sleeping with the head raised high upon a thick pillow or bolster, are ways in which young persons often grow out of shape.
SEAT TOO HIGH.
7. The Clothing.—Wearing the clothing tight about the waist often produces serious deformities of the bones of the trunk, and makes the chest so small that the lungs have not room to act properly. Tight or high-heeled shoes also often deform and injure the feet and make the gait stiff and awkward.
8. Broken Bones.—By rough play or by accident the bones may be broken in two just as you might break a stick. If the broken parts are placed right, Nature will cement them together and make the bone strong again; but sometimes the bones do not unite, and sometimes they grow together out of proper shape, so that permanent injury is done.
9. Sprains.—In a similar manner the ligaments which hold the bones together, in a joint, are sometimes torn or over-stretched. Such an accident is called a sprain. A sprain is a very painful accident, and a joint injured in this way needs to rest quite a long time so that the torn ligaments may grow together.
10. Bones out of Joint.—Sometimes the ligaments are torn so badly that the ends of the bones are displaced, and then we say they are put out of joint. This is a very bad accident indeed, but it often happens to boys while wrestling or playing at other rough games.
11. Children sometimes have a trick of pulling the fingers to cause the knuckles to "crack." This is a very foolish and harmful practice. It weakens the joints and causes them to grow large and unsightly.
12. When a man uses alcohol and tobacco, their effects upon the bones are not so apparent as are the effects upon the blood, the nerves, and other organs; but when the poisonous drugs are used by a growing boy, their damaging influence is very plainly seen. A boy who smokes cigars or cigarettes, or who uses strong alcoholic liquors, is likely to be so stunted that even his bones will not grow of a proper length and he will become dwarfed or deformed.
SUMMARY
1. To keep the bones healthy they must have plenty of healthful food.
2. The whole-grain preparations furnish the best food for the bones.
3. Walking at too early an age often makes the legs crooked.
4. Hard work at too early an age stunts the growth.
5. Bad positions and tight or poorly-fitting clothing are common causes of flat chests, round shoulders, and other deformities.
6. Tight or high-heeled shoes deform the feet and make the gait awkward.
7. The bones may be easily broken or put out of joint, or the ligaments may be torn by rough play.
8. Alcohol prevents healthy growth.