IRLF HYSIOLOQY T HYGIENE FOR CHILDREN PHYSIOLOGY as FOR CHILDREN BY EGBERT EADIE Principal of School 72, Borough of Queens, New York City, AND ANDREW EADIE, M.D. Professor of Physiology, Ontario Medical College for Women, Toronto, Canada. NEW YORK CHARLES SCRIBNER'S SONS 1909 COPYRIGHT, 1904, Br UNIVERSITY PUBLISHING CO. ENTEBED AT STATIONERS' HALL, LONDON, ENGLAND. COPYRIGHT, 1908, BY CHARLES SCRIBNER'S SONS EDUCATION DEPT. PREFACE IT is important that every boy and girl shall become familiar, while at school, with the primary laws of health. A knowledge of the structure of the body, its parts, and their uses, is the foundation for an intelligent understanding of these laws. Anatomy and physiology are, therefore, treated here chiefly as an aid to the teaching of hygiene. In order that children may readily understand the story of their bodies, it is told in clear, simple language, and with a minimum of technical terms. Great care has been taken in the treatment of each chapter and topic to observe the relative importance of the various organs. Those which have more important functions are de- scribed in greater detail than those whose functions are less important. The interdependence of organs has also been kept prominently in view, in order that the pupil may realize that he is learning about an active living body, and not about isolated parts. The value of this book as a teaching instrument is greatly enhanced by the best illustrations that could be obtained. The authors were given carte blanche by the publishers, and in- structed to spare no expense in securing pictures that would illustrate the text in the best possible manner. Color has been used to make the illustrations more attractive, and also to make 4 PKEFACE it easier to differentiate parts, but there has been no uniform attempt to imitate the natural color of the parts. The law requiring that twenty-five per cent, of the text mat- ter shall treat of " the nature and effects of alcoholic drinks and other narcotics " has been complied with. The injurious effect of alcohol upon different organs is stated plainly and con- cisely ; and, in addition to that, as much emphasis as possible has been placed upon the positive benefits in improved health and strength which arise from abstinence from the use of alco- holic drinks and tobacco. In order that this lesson may make a deep and lasting impression, it is presented in the concrete form of letters written by men whose opinions will at once be accepted as worthy of confidence. The authors take pleasure in acknowledging their obligations to the gentlemen who kindly furnished the letters contained herein, and also to Mr. M. Anagnos, Director of The Kinder- garten for the Blind, in Boston, Mass., for annual reports con- taining the story of Thomas Stringer. CONTENTS CHAPTER PAGE I. INTRODUCTION 7 II. BONES 17 III. MUSCLES 33 IV. THE FOUR KINDS OF FOOD 45 V. DIFFERENT ARTICLES OF FOOD 52 VI. How OUR FOOD is CHANGED INTO BLOOD . . 60 VII. How THE BLOOD BUILDS UP THE BODY . . . .78 VIII. DRINKS WHICH CONTAIN ALCOHOL 94 IX. BREATHING . 106 X. THE SKIN 115 XI. THE BRAIN, SPINAL CORD AND NERVES . . . . 130 XII. THE FIVE SPECIAL SENSES 141 APPENDIX 159 KEYS 193 GLOSSARY 197 INDEX . 201 CHAPTER I THE BODY A LITTLE boy whose name was Charles lived in a great city. In the hall of his father's house stood a tall clock, and little Charles used to stand before it and watch the heavy pendulum swing back and forth, and listen to the regular tick-tock, tick-tock, like a voice speak- ing to him. At times he would hear a sudden click, and then out would ring a bell, clear and sweet, telling that an- other hour had passed. What made the pendulum swing? What made the hands go round? What made the bell ring at exactly the right time every hour ? Little Charles could not tell. So day after day he would stand and watch the old clock and wonder about it. THE OLD HALL CLOCK. 8 PHTSfOLOGY FOR CHILDREN One morning when he came down stairs there was no sound in the hall. He looked up at the clock and saw that the pendulum was still. The clock had stopped. Later in the day a strange man came to fix it. Charles watched him as he took off the front. Inside were wheels and chains and weights. The man took the wheels out one by one, polished them, oiled them, and put them back, fitting each part nicely to the other. Then he wound up the weights, put the front on the clock again, started the pendulum to swing- ing, and once more Charles heard the INSIDE THE CLOCK, peasant tick-tock, tick-tock, to which he loved to listen. Now he knew what made the hands go round, the pendulum move, and the bell ring. It was the wheels and the chains and the weights inside. While Charles had often wondered about the clock, he had never thought very much about himself. And yet a boy is much more wonderful than a clock. It can move its hands only round and round ; he can move his hands in every direction. It can say only tick-tock; he can say whatever he wishes. It can THE BODY 9 stand only where it is placed; he can run and jump and play. What gives a boy the power to do all these things ? Would you like to know ? The body of a boy, like the body of a clock, has many strange things inside not wheels, chains and weights, but other things which are just as strange, and which all work together. The picture on page 1 1 shows part of a body with the front taken' off. Look at it and you will see some of these things. From this little book you can learn something about your body and the things inside it. Each chapter tells you the name of some part of the body, how it looks, and where it is ; that is ANATOMY. Next, it tells you the use of each part ; that is PHYSIOLOGY. And then it tells you how to take care of each part; that is HYGIENE. The body. We often call that part of a man which you see in the picture the body, but its real name is the trunk. The upper part of the trunk is the chest, the lower part is the abdomen. Joined to the trunk are the head, arms and legs. All these together make the body. Organs. The works of a clock are called a ma- chine. They are made to do special work, and are afterwards put into the body of the clock. The 10 PHYSIOLOGY FOB CHILDREN strange things that you see in the chest and abdomen also do special work,, but they are called organs. They grow in the body from the first, and are parts of it. Each part of the body that does special work is called an organ. The eye is an organ of sight. The ear is an organ of hearing. The hands and feet also are organs. Many organs are very delicate, and so we find them placed in hollow cases of bone, called cavities, to keep them from being injured. For this reason the brain, which is the organ of the mind, is shut up in the skull, and many important organs are shut up in the large cavities of the trunk. Look at the picture on page 1 1 and you will see the ribs and the breast bone, which protect the cavities. Behind the ribs are organs called lungs. In the centre of the neck you can see a tube called the windpipe, which extends upwards from the lungs. The air which you breathe passes through the windpipe into the lungs. Both the lungs and the windpipe have been colored purple in the picture. Turn to the picture on page 14. The ribs have been taken off, one lung has been taken out, and the other lung has been drawn back so that you can see the cavity of the chest. There you will see an organ A VIEW OF THE INSIDE OF THE TRUNK. (See Appendix for Key.) 12 PHYSIOLOGY FOE CHILDREN called the heart, colored red. Above the heart are red and blue tubes which go from it to other parts of the body. Just under the heart and lungs you can see the partition which separates the chest from the ab- domen. Below this partition is an organ called the liver. Below the liver is the stomach. In the picture the liver has been colored brown, and the stomach yel- low, with red lines over it. A tube goes from the mouth down to the stomach. It is just behind the windpipe, and so cannot be shown in the picture. It is through this tube that food passes from the mouth to the stomach. Below the stomach, neatly folded and curled up, is the intestine. Although the body has many organs, all work together and help one another. If one organ is in pain and cannot do its usual work, other organs share the injury and are unable to do their work well. Cells. If you cut open a ripe orange and pick it apart carefully, you will find that it is made up of a great number of little sacs which are full of juice. THE CELLS OF AN ORANGE : SACS FULL OF JUICE. LITTLE THE BODY 13 These are called cells. They are packed closely aiid are held together by small threads, or fibres. The fibres in the orange are found either as small threads, or woven together in thin sheets like tissue paper. All vegetables and animals are made up of cells. Every part of your body, every organ in it, all your muscles and bones, your skin and hair are built up of cells. Most cells are so small that you cannot see them unless they are made to look much larger than they really are by the use of a microscope. This is true, for example, of the cells of a grain of wheat, a potato or a blade of grass. It is also true of the cells of muscle, bone, skin, and hair. Cells are held together by little fibres. Many of these fibres are joined together into sheets, or tissues. Because these tissues connect cells and hold them together, they are called connective tissue. Growth and health of the body. We g;row rapidly in early life. As the years pass by we grow more and more slowly, but continue to grow until about our twenty-fifth year. Part of a child's food is used to make him grow, and so he requires more to eat in proportion to his size than a grown person does. Exercise and work that is not too hard promote growth and health. ANOTHER VIEW OF THE INSIDE OF THE TRUNK. (See Appendix for Key.) THE BODY 15 Plain wholesome food and pure drinking water are necessary to health. Pure air and sunshine are also necessary for health and growth. Notice the sickly plants that are kept too long in a north window, or in a cellar, where the sun cannot shine on them. Notice, too, how pale are the unfortunate children who are crippled and unable to run about outdoors. Whatever else you may be afraid of, never be afraid of sunshine and fresh air. The continued use of alcoholic liquors and tobacco often injures the body. The harm that they do to some parts of the body may be serious enough to re- quire the aid of a physician, who treats such injury with as much care as if it were due to accident or contagion. Besides the physician, the employer of labor knows that alcoholic liquor and tobacco injure the body; for he finds that they unfit a man for doing his best work. In fact; many people refuse to employ a young man who uses alcohol or cigarettes; and it is an advantage to a young man in any calling or profession if it is known that he abstains entirely from the drinking of alcoholic liquor. The following letter from Mr. John Claflin, President of one of the largest dry goods companies in the United 16 PHYSIOLOGY FOR CHILDREN States, illustrates the opinion held by prominent business men in regard to the drinking of alcohol: THE H. B. CLAFLIN COMPANY, NEW YORK, April 26, 1907. My Dear Sir : I do not knowingly employ a young man who uses alcohol. Its use, even occasionally, renders him unreliable and impairs his ability to do intelligent and constant work. In the struggle for success in life, the total abstainer has a great advan- tage over the moderate drinker. The immoderate drinker is out of the race. Very truly yours, (Signed) JOHN CLAFLIN, President. We have learned that : 1. The body consists of distinct parts. 2. Anatomy tells us what the different parts of the body are like 3. Physiology tells us the uses of the par.ts of the body. 4. Hygiene tells us how to take care of the body, s 5. An organ is any part of the body that has a special work to do. 6. Some of the most important organs, such as the brain and heart, are contained in cavities in the body. 7. The body is made up of cells held together by connective tissue. 8. The use of alcoholic liquors and tobacco often injures health. CHAPTER II THE FRAMEWORK OF A COTTAGE. BONES The framework of the body. In this picture you can see a cottage which carpenters are building. They have fastened to- gether strong pieces of timber, to make the framework. This framework will give shape to the cottage, and support its parts. The carpenters will nail boards and shingles upon the outside, and will lay floors and put in doors and windows. The frame- work will support all of these, and the fin- ished cottage will look like the one in the second picture. The human body has a framework of bones which gives to the body its general THE FINISHED COTTAGE. 18 PHYSIOLOGY FOR CHILDREN THE FRAMEWORK, OR SKELETON, OF THE BODY. BONES 19 shape. It supports the flesh which is laid over it, and also protects the tender parts of the body which are placed within it. If the skin and flesh were removed from a body, so that you could see this framework, which we call the skeleton, it would look like the picture on page 18. What bones are made of. Bone is a hard substance. You can find out by two little experiments something about the materials of which bone is made. Place a bone in a hot fire for three or four hours. It will keep its shape, no matter how long you burn it; but if you try to handle it after it is burned, it will crumble to pieces. The part of a bone that remains af- ter it has been burned is called min- eral matter. Get two ounces of muriatic acid at a drug store, and put the acid and a pint of water into a bottle. Then put the leg-bone of a chicken into the bottle, and leave it there four days. When you take the bone out, you will find it so soft that it can be tied into a knot. The A CHICKEN'S LEG-BONE TIED INTO A KNOT. 20 PHYSIOLOGY FOE CHILDREN part of a bone that remains after it has been in acid is called animal matter. The fire burned away the animal matter of one bone, and the acid dissolved out the mineral matter of the other bone. The animal matter in bone resembles gristle. It makes the bones tough. The mineral matter consists largely of lime. It makes the bones hard and strong. In early life the bones are elastic and will bend before they break. As people grow old their bones become less elastic and more brittle. It was long taught that this brittleness was caused by a loss of animal matter and an increase of mineral matter. Now, however, it is taught that bones become brittle with age because they lose both animal and mineral matter. On account of this loss the bones of old people are not strong and break easily. How bones look. If you examine a short or a flat bone which has been well dried, you will find that the outer part is hard and firm. When the bone is broken, the inner part is seen to be like a sponge, full of small holes. The holes in the spongy part are connected with one another, so as to form little canals. BONES 21 A long bone consists of a round shaft, with enlarged ends. The material of the ends is like that of a short bone. If you saw the shaft across, you will see a ring of hard bone with a hollow space running through it from end to end. This hollow space, when the bone is fresh, contains a yellow substance called marrow, which consists largely of fat and small blood tubes. A fresh bone is pinkish white, because it contains blood. An old dried bone is white, be- cause it has lost the blood that was in it. Joints. In order that the bones of the body may make a frame- work^ they must be fastened to- gether, just as pieces of timber must be fastened together to make the framework of a cottage. A place A LONG BONE - in the skeleton where bones are fastened together is called a joint. Every one has seen the hinges on a door. They are simply joints of metal, which allow the door to open and close. Many of our joints are PHYSIOLOGY FOR CHILDREN like hinges ; they allow bones to move upon one an- other easily. To understand the value of such joints you have only to try to play ball without bending your arms at the elbow, or to write without bending your fingers at the knuckles, or to walk without bending your knees. Some joints, like those of the elbow and shoulder, allow the bones to move freely. Others, like those of the spine, allow the bones to move only slightly; while the joints of the skull are fixed they do not allow the bones to move at all. The ends of the bones at joints which allow movement are covered with a tough, smooth substance called car- tilage, which is elastic like rubber. The bones are held together at the joints by short, tough, white, glistening bands of connective tissue, called ligaments. You can see the ligaments of the wrist and the hand in this picture. Ligaments are soft and bend easily, so as to allow great freedom of movement ; yet they are strong, and LIGAMENTS OF WRIST AND HAND. BONES 23 BONES OF THE WRIST AND HAND. which enough of this fluid is made to keep the ends of the bones slippery, so that they move smoothly upon one another. Chief bones of the body. It takes a great many bones to make the skeleton. There are about two hundred. This seems a large nuni- tough, and hold the bones securely in their right places. The hinges of a door some- times work with difficulty. A drop or two of oil will cause them to move freely. Many of our joints are sup- plied with a fluid which helps them to move easily, as oil helps the hinges. The inner surfaces of the ligaments have a smooth lining, in BONES OF ANKLE AND FOOT. 24 PHYSIOLOGY FOR CHILDREN ber, but all are needed. Each has its own place and its own use. Look at the pictures on page 23 and compare the bones of the wrist and hand with those of the ankle and foot. The wrist and hand contain twenty-seven bones. Can you find them all in the picture ? The ankle and foot contain twenty-six bones. Count them in the picture. There are eight small bones in the wrist and seven in the ankle and instep. How many do you see in the palm of the hand ? How many in the foot be- tween the instep and the toes? How many in the thumb ? in the great toe ? How many are there in each of the other toes ? How many in each of the fingers ? The bones of the wrist, hand, and fingers are arranged in rows, and held in place by strong liga- ments. These ligaments are so elastic that the hand and fingers can move rapidly and easily in different kinds of work and play. The bones of the foot, ankle, and instep also are held together by strong and elastic ligaments. You see that the hands and feet are made on much the same plan, yet they serve very different purposes. It is not easy to use the feet as we use the hands, to hold and handle things, because the toes are short, and the bones of the great toe lie side by side, or parallel BONES 25 with the bones of the other toes. The bones of the thumb are not parallel with those of the fingers, but are so arranged that the tip of the thumb can be made to touch the tips of the fingers. This is im- portant, for it gives us power to grasp and hold with the hands. Now turn back to the picture of the skeleton on page 1 8 and compare the bones of the arm with those of the leg. How many bones do you find from the shoulder to the elbow ? From the hip to the knee ? There is one small bone which forms the front of the knee and protects it. It is called the knee-cap. The elbow has no such bone. How many bones extend from the elbow to the wrist ? How many extend from the knee to the ankle ? Which is the largest bone in the skeleton ? The backbone, or spine, is made up of thirty- three bones, which are placed one upon another like spools on a string. In children each bone is separated from the one above it and from the one below it by a thin layer of cartilage. This cartilage allows the bones to move, so that the spine may bend and turn easily. The cartilage acts also as a cushion to prevent injury from a sudden jar. In grown people the nine lower bones of the spine are united so as to form only two bones. PHYSIOLOGY FOK CHILDREN Notice this picture of one of the bones of the spine. The small holes on either side are for blood tubes, while the large hole in the centre is for a delicate cord which passes down from the brain, and is called the spinal cord. The spine is sometimes called the spinal col- umn, because it ONE OF THE BONES OF THE SPINE. forms a strong column, or pillar, to support the upper part of the body. The skull is made up of a number of bones which are joined at their edges. The picture on page 27 shows where some of the bones are joined. The skull forms a box that holds the brain. In the front part of it are two THE SPINAL hollows, called sockets, for the eyes. COLUMN. ~ , , , Only the upper part 01 the nose is made of bone. The lower part is composed of cartilage. BONES 27 A VIEW OF THE SIDE OP THE SKULL. the spinal cord extends from the brain downwards into the spine. The ribs form a bony cage which protects the heart and lungs. All the ribs are fastened to the spine, and most of them to the breast-bone. They are moved gently upwards and downwards as we breathe. Look at the picture on the next page and tell how The lower jaw is fastened to the skul] by two joints, one on each side of the face. The jaw can move up and down, and also from side to side. The picture below gives a view of the base of the skull. It shows the hole through which A VIEW OF THE BASE OF THE SKULL. 28 PHYSIOLOGY FOE CHILDREN many ribs you see on each side. How many on each side are fastened directly to the breast-bone ? How many are not fastened to anything in front? How many are fastened in front to ribs above them ? The collar-bone can easily be felt at the upper part of your chest in front. It extends from the shoul- der to the breast-bone, and serves as a prop to the shoulder. The shoulder-blade, as you will see from the' picture of the skeleton, is a strong bone which is spread out like a fan over the upper ribs at the back. At the centre, from which the fan spreads, is a shallow cup-like cavity into which the upper end of the arm- bone fits, and makes the shoulder-joint. The shoulder- blade is connected with the collar-bone also. Hygiene. We often hear that "as the twig is bent the tree is inclined." This is certainly true of the bones. The soft bones of children may be bent THE RIBS AND BREAST-BONE. BONES into awkward shapes by wrong positions and unsuit- able clothing. If the bending continues, the bones will harden into these shapes and the body will be de- formed. ill X-RAY PHOTOGRAPH OF BONES OF FOOT WITHOUT SHOE. X-RAY PHOTOGRAPH OF BONES OF FOOT IN SHOE. The foot may be forced out of shape by tight, or badly fitting shoes. The picture on the left was taken without the shoe, and you see the natural shape of the foot. The picture on the right shows how the bones of the foot may be pressed out of shape by a tight shoe. 30 PHYSIOLOGY FOR CHILDREN The ribs may be pressed inward by tight clothing about the waist. In this way internal organs are sometimes pushed out of place, so that they cannot do their work as they should. FROM AN X-RAY PHOTOGRAPH OF A STRAIGHT SPINE. Every one should form the habit of sitting and standing upright. By constant stooping you may become round-shouldered. If you form the habit of holding your body in a one-sided or stooping posi- tion you may gradually grow out of shape, and you BONES 31 will find it very difficult, or even impossible, to straighten up again. For this reason desks in a school-room should al- ways be suited to the height of pupils. If the desk FROM AN X-RAY PHOTOGRAPH OF A CURVED SPINE. is too high, the right shoulder is raised above the left, and the body will be bent to one side. If the desk is too low, the habit of stooping will be formed, and the pupil will become round-shouldered. Here we have the picture of the spine of a girl when she was seven- 32 PHYSIOLOGY FOB CHILDREN teen years of age. Her spine became curved while she was attending school. The seat should be so arranged as to allow the feet to rest comfortably. If the feet have no sup- port their weight may cause the thigh bones to be bent out of shape. A sudden twist or wrench of a joint may over- stretch or tear the ligaments and produce an injury which is called a sprain. A sprained joint should always have rest. We have learned that : 1. A framework of bones gives shape to the body, and supports and pro- tects other parts of it. 2. Bone is a hard substance composed of animal matter and mineral matter. 3. The outer part of all bones is hard and firm, the inner part is either spongy or hollow. 4. A joint of the body is a place where two bones are fastened together. 5. The ends of the bones of a movable joint are covered with cartilage, and are held together by ligaments. 6. Movable joints are furnished with oil. 7. Bones may be forced out of shape and may remain so. CHAPTER III MUSCLES What muscles do for us. A bit of stone from the mountain side may travel down to the seashore and become one of the pebbles at the water's edge, but in its long journey it never moves itself. The rain washes it down into a stream, and the stream carries it to the shore. A seed that falls to the ground w r ould perhaps grow better in the soil of a neighboring field, but it cannot get there unless the wind carries it. It has life, but it has no power to move. Watch, however, the graceful movements of a bird as it flies from tree to tree. It can make these move- ments because it has muscles. The movements of all animals, from the tiny insect to the great elephant, are due to muscles. Even the slightest motion of the body, such as the winking of an eyelid, is produced by muscles. When a ball is lying on the floor it has no power to move itself, and when rolling it has no power to stop itself. But if a boy is running he can stop when he chooses, because he has muscles. Our muscles not 34 PHYSIOLOGY FOE CHILDREN THE MUSCLES OF THE SURFACE OF THE BODY. MUSCLES 35 only enable us to move ; they also enable us to keep from moving. It is by means of our muscles that we can hold an arm out straight from the shoulder, and sit or stand upright. When we become weak from ill- ness, we have to lie in bed because our muscles can- not hold us up. The muscles serve still another purpose. They cover the skeleton and give to the body its graceful curves and beautiful outline. Very few boys and girls have ever seen a whole muscle, but every one has seen a beefsteak, and that is a slice of muscle. We are eating muscle whenever we eat the lean flesh of a chicken, lamb, or other animal. How muscles act. On the left we have a picture of a muscle taken from the leg of a frog. If this were a real muscle instead of a picture, and we were to prick it with a pin, it would at once become shorter ; that is, it would contract. It would then look like the picture on the right. After con- tracting, a muscle will return to the shape that it had before ; that is, it will relax. It is by means of their power to contract and relax that the muscles are able to move the body. A FROG. LEG MUSCLE OP 3(5 PHYSIOLOGY FOE CHILDREN Bare your right arm, and hold it up before you, with the palm of the hand toward you. Close your hand and then open it again. Watch the arm while you do this, and you will see muscles lying along the front of it contract and pull your fingers down. Then muscles lying along the back of it contract and pull the fingers up again. Here are pictures of the bones of the arm, with one muscle in its natural posi- tion. The other muscles of the arm are not shown. The upper end of this muscle is fastened to a bone at the shoul- der, and the lower end is fastened to another bone below the el- bow. When this muscle contracts, it pulls on the bone to which its lower end is fastened, and the forearm and hand are moved upward. UNCONTR ACTED MUSCLE OF UPPER ARM. CONTRACTED MUSCLE OF UPPF.R ARM. MUSCLES 37 Why muscles contract. In our bodies there are many silvery threads, called nerves, which, like tele- graph wires, carry messages. Whenever you decide to move your arm, your hand, or any part of your body, a message is sent out by your brain. This mes- sage travels quickly along a nerve to the proper mus- cles, and on its arrival a contraction of those muscles takes place. Like faithful servants they obey your slightest command. Kinds of muscles. Some muscles, such as those of the arms and legs, contract only when we order them to do so. They are under the control of our will and for this reason they are called voluntary muscles. There are many other muscles which are not under the control of the will. We can neither make them contract nor prevent them from contracting, so they are called involuntary muscles. Your heart is made up of involuntary muscles. You have no control over its action ; it keeps on beating whether you are awake or asleep. Shapes of muscles. Muscles are of many differ- ent shapes and sizes. Some are thin, round and long; some are short and broad ; while others are spread out like a fan. The shape and size of each are suited to the work it has to do. 38 PHYSIOLOGY FOE CHILDREN THREE FIBRES OP VOLUNTARY MUSCLE. (Magnified.) What muscles are made of. Muscles are made of very fine threads, or fibres. Here is a picture of three fibres of voluntary muscle, very much magnified, and also a picture of a bundle of fibres. Each volun- tary muscle consists of bundles of these fibres. The bundles and fibres are held together by con- nective tissue. When lean meat is boiled the connective tissue is soft- ened and the muscle can be easily separated into fine threads, and yet the smallest thread con- sists of many fibres. The tendons. Some muscles are attached at both ends directly to bone. Other muscles end in white glistening cords which are fast- ened to bone. These cords are called tendons. The tendons are composed of hard connective tissue, which is tough and strong and will not stretch. If you look at the back of your hand while your A BUNDLE OF MUSCLE FIBRES. (Magnified.) MUSCLES 39 fingers are working rapidly, you will see, moving under the skin, the tendons which belong to the muscles on the back of the arm. Exercise. Our muscles require food. They get it from the blood, through little tubes. Each time a muscle contracts these little tubes become larger, and the muscle receives an increased amount of food. Exercise causes the muscles to contract again and again. While they are contracting they get more food from the blood, and therefore increase in size and strength. It is because of more exercise that the farmer's boy who works in the fields is generally stronger than the boy who lives in the city. The blacksmith can pound the red hot iron with great force because his muscles are large and strong, but his muscles have become large and strong because for years he has been pounding the iron. Muscles that are not used soon become small and weak, for they do not receive proper supplies of blood, and so are not well fed. This is shown in the case of a broken arm. After an arm has been in a sling for a few weeks its muscles become so weak, from lack of exercise, that it is hard for them to make even ordi- nary movements. All parts of the body should be exercised, so that 40 PHYSIOLOGY FOB CHILDREN one part may not remain weak while other parts be- come strong. Not all people are benefited by the same kind of exercise. Some tire sooner than others. Some need harder work than others. Therefore it is foolish to insist on taking any particular exercise merely because some one else finds it useful. Such exercises as those with light weights, which can be done easily EXPERIMENT TO SHOW EFFECT OF ALCOHOL ON THE MUSCLES. and quickly, will benefit a person more than exercises which require all his strength. Effect of alcohol on the muscles. Alcohol weakens the muscles. Careful experiments to show that muscles are affected by small quantities of alcohol were recently made both in Switzerland and Belgium. This picture shows how these experiments were made. The arm was fixed on a board by means of MUSCLES 41 two clamps, so as to keep it still. The first and third fingers were placed in tubes, which kept them from interfering with the second finger. A string, fastened to the second finger, was passed over a pulley and attached to a weight. o Every time the second finger was bent upwards the weight was lifted. The experiments consisted in bend- ing and straightening out the finger until its muscles became so tired that they could not lift the weight again. It was found that the muscles of the finger could do more work when no alcohol was taken than they could when even a small amount was taken. A man who develops his muscles by exercise until they become large and strong is called an athlete. The following letters show that when athletes are try- ing to become as strong as possible it is; usual for them to do without alcohol and tobacco. This proves that the use of either alcohol or tobacco is considered injurious to the muscles. THE CORNELL NAVY. ITHACA, K Y., November 7, 1899. Gentlemen : Answering your favor asking my opinion as to the use of alcoholic liquors and tobacco by men who are train- ing for rowing contests, I would say : PHYSIOLOGY FOR CHILDREN A CREW OF ATHLETES. First : As to alcoholic liquors, I do not believe in the use of any form of alcoholic liquor for men in training. I know that in England, and sometimes in this country, it is used by other trainers, but I have found, in my experience, that young men are much better off, and do better work without alcoholic stim- ulants than with them, and they are, therefore, absolutely prohibited in our training. The use of alcohol in any shape I think wholly unnecessary for any young man who has sufficient bodily health to be athletic, and in many cases, as I know, it is positively injurious if used. Second : As to tobacco, I believe young men do better work when not using tobacco than when using it, and it is prohibited in our training here at Cornell University. Respectfully yours, CHAS. E. COURTNEY. MUSCLES 43 NEW YORK, March, 12, 1900. Dear Sir: Eeplying to your favor of the 10th inst., I will say that I do not use alcoholic liquors in any form, neither do I use tobacco. I have never used them. I do not believe any athlete can meet with success who does use either alcohol or tobacco. Respectfully yours, FRANK L. KRAMER. (National amateur cycling champion of America, 1898, 1899.) NEW HAVEN, CONN., Jan. 11, 1900. Dear Sir: Yours of the 10th inst. at hand. It is abso- lutely necessary for a college or school athlete who is striving to win a place on any team to have endurance; especially is this true in rowing and football. This can be accomplished to the greatest degree only by abstaining from the use of tobacco and alcoholic drinks while in training for said team. Very truly yours, M. F. MCBRIDE, Capt. Yale Football Team of '99. 173 BROADWAY, NEW YORK, April 4, 1901. Dear Sir: There is nothing which goes to make a better athlete, nothing which gives a man greater power of endurance than total abstinence from the use of alcoholic drinks and tobacco. At the opening of college, all the candidates for the football team are called together and informed of the plans for the year. They are also told at what date rigid training will begin. Those men who are using liquor and tobacco have now a chance 44 PHYSIOLOGY FOR CHILDREN gradually to leave them off altogether, so that at the set date every one starts in on good, hard, conscientious work. At Princeton, there have been several opinions given in re- gard to the use of ale at the training table. In some years the men who wished to have it have been given one glass of ale with their dinner, and many believe in its use. Beer and other alcoholic liquors are never used. I think a team is better off without any of them. No one is expected to use tobacco. A man who is using tobacco and alcohol contrary to orders during the season is easily detected, and is dropped from the squad. Yours truly, WILLIAM H. EDWARDS, Capt. '99 Football Team, PRINCETON UNIVERSITY. We have learned that : 1. Muscles enable us to move. 2. Muscles give a pleasing shape to the body. 3. Muscles can contract and relax. 4. Muscles which are fastened to bones pull on them in contracting, and thus produce movement. 5. Muscles contract because messages from the brain come to them along nerves. 6. Some muscles are voluntary, others are involuntary. 7. Muscles are made up of fibres. 8. Some muscles end in tendons, which are fastened to bones. 9. Exercise makes muscles stronger. 10. Muscles can do better work without alcohol and tobacco than with them. CHAPTER IV THE FOUR KINDS OF FOOD Food builds up the body. Everything wears away as time passes. Your shoes wear out and have to be repaired with leather. Your warm winter stock- ings wear out and have to be darned with yarn. Boys' shirts and girls' dresses wear out and have to be mended with cloth. Our bodies, too, are wearing out from day to day and have to be repaired, not with leather, or yarn, or cloth, but with bread and milk, meat and vegeta- bles, and other things that we eat and drink. Some of your skin wears out every day. If you scrape the skin of your arm gently with a knife, you will collect on it a great many particles that are just ready to fall away. Even your muscles and your brain wear out, although you cannot see the worn-out particles. But as each particle wears out it is washed away and a new one is made in its place. The material out of which these new particles are made is obtained from food. Food is any substance that can be used to nourish the body without injuring it. Besides being used for repair, food produces the heat of the body ? 46 PHYSIOLOGY FOR CHILDREN the case of children some food is used up also in. growth. Kinds of food. We must eat different kinds of food if we wish to be strong and healthy, because no one kind can supply all the different materials that are needed to build up every part of the body and to furnish it with heat and power to work. This is the reason why we have several kinds of food on our tables for each meal. Sugar is a useful food, but if you ate sugar for breakfast, dinner, and supper, day after day, and ate nothing else, you would become very thin and weak, and, in the end, would starve io death. It is easy to make a long list of different articles of food that are commonly used. Some of these are beef and mutton, turkey and chicken; fish and oysters, potatoes and cabbage ; bread, butter, and eggs ; pie and cake ; fruits ; water, milk, tea, coffee, cocoa, and choco- late. This by no means ends the list, yet in spite of the many different articles that might be named, there are only four different kinds of food, and everything that you eat belongs to one or more of these four kinds. Proteid. One of the four kinds of food is called proteid. This is a strange name, yet you have seen THE FOUR KINDS OF FOOD 47 proteid many times. The white of an egg is one kind of proteid, and is called albumen. Before it is cooked it has a clear, glassy appearance, and is quite soft, like thin jelly. You can see through it very much as you can see through glass. Muscle that is, lean meat of all kinds is made up largely of proteid s. If you should look at a thin strip of muscle through a microscope, you would see the clear, glassy-looking proteid, somewhat like the white of an egg in appearance. Milk and cheese have much proteid in them. Many vegetables and grains also contain it. The chief use of proteids is to build up and repair the tissues of the body, but they can also be used to produce heat and power to work. Starch and sugar. Starch and sugar are another of the four kinds of food. We may not think that we are eating starch when we eat bread, cake, rice, or potatoes ; yet all of them contain much starch. It forms a large part of all grains, such as wheat, corn, oats, and rice. Food containing starch is sometimes called starchy food. Starch and sugar are considered the same kind of food because after starch has been eaten it changes into a form of sugar. 48 PHYSIOLOGY FOR CHILDREN Here is a picture showing how the starch in wheat looks through a microscope. Each of the little starch grains is enclosed in a thin but very tough envelope. -9 Q STARCH GRAINS IN WHEAT. (Magnified.) When starch is cooked, its grains swell up and burst their envelopes. Below is a picture of the starch grains of a potato as they appear when seen through a microscope. Starchy food is needed to produce heat and power to work. STARCH GRAINS IN POTATO. (Magnified.) THE FOUR KINDS OF FOOD 49 Fat. Fat is the third kind of food. As a rule, children do not like fat meat, but they like butter, and yet butter is only fat obtained from milk. Here is a picture of a drop of milk as it looks through a microscope. It shows the fat, Or butter, in ROUND PARTICLES OF FAT IN A DROP little round particles. OF MILK SEEN UNDER A M < CROSC0 ^. Fat also produces heat and power to work. Mineral food. The fourth kind of food is mineral food, and consists of water and salt. Common table salt is a very important food. You eat even more of this salt than you think, for nearly every article of food contains it. It is found in all the fluids and tis- sues of the body. You could not live without it. In his book, "In Darkest Africa," Stanley tells of regions where savages are accustomed to travel many hun- dreds of miles under great difficulties to obtain a sup- ply of salt. Many of the lower animals also have a natural craving for it. Besides the common salt that we have on our tables 50 PHYSIOLOGY FOE CHILDREN there are many other kinds, salts of lime, salts of potash, salts of sodium, salts of phosphorus, salts of iron, as well as others. Small portions of some of these salts are contained in almost every article of food that we eat or drink. One use of salts is to help in making bone. The hardness of bone is due to the lime salts it contains. Water, our natural drink, is also a mineral, and one that we cannot live without. We need it to dissolve our food, and also to dissolve and wash away the waste matter. More than half of our body consists of water. In addition to that which we drink, we get a great deal of water in beef, bread, potatoes, and other things we eat. It is a very important matter to get pure drinking water. If we get it from a well, the well should be kept thoroughly clean. The ground around the well should, if necessary, be raised so as to be higher than the ground farther away. The surface water will then run away from the well instead of draining into it. Every care should be taken to allow nothing near the well which can in any way make the water impure. Impure water may be very injurious, for it may carry germs of disease. Even water that is clear and spark- ling may be harmful THE FOTJK KINDS OF FOOD 51 THE GROUND AROUND THE WELL SHOULD BE HIGHER. Many towns and cities take their drinking water from streams or lakes by means of underground pipes. Every one who lives on the banks of such streams should be careful not to allow filth of any kind to get into the water that others are going to drink. We have learned that : 1. Food builds up the body and repairs it as it wears out. 2. Food is the fuel of the body and keeps it warm. 3. Food gives us power to work. 4. We must eat different kinds of food. 5. There are only four kinds of food. 6. Proteids build up and repair the tissues of the body. 7. Starch, sugar, and fat produce heat and power to work. 8. Mineral food is needed to make bone. 9. The body needs water. 10. Water often contains germs of disease. CHAPTER V DIFFERENT ARTICLES OF FOOD The perfect food. Milk is a perfect food for young children. It is both food and drink for them. Milk consists of water, proteid, fat, sugar, and salts. The fat, when separated by churning, is called butter. What is left of the milk is called buttermilk. It contains all of the milk except the fat, and is a useful food. The fat and the proteid together can be separated from the rest and made into cheese ; the water, sugar, and salts that are left behind are called whey. Milk must be pure to be healthful. Great care should be taken to keep it clean. The stables, cows, and those who do the milking should be strictly clean; and all vessels in which milk is put should first be thoroughly washed with boiling water. Milk should not be kept in a damp, mouldy cellar, but in a clean, dry, well-aired place. Animal food. Almost all animal food is more readily digested than vegetable food. Milk, "the per- fect food," is an animal food. Eggs, though hardly a perfect food having too little sugar are valuable articles of diet, for they consist of proteid, fat, and DIFFERENT AETICLES OF FOOD 53 some mineral matter. Usually they are easily digested if they are soft-boiled, poached, or made into cus- tards. Meat consists of water, proteid, fat, and some salts. Beef, lamb, chicken and turkey are the most digestible forms of meat. Fresh fish also is easily digested, and forms another valuable article of diet. Vegetable food. Such cereals as wheat, rice, bar- ley, oats and rye consist of starch, proteids, water, salts, and fat. The most important article of food made from cereals is bread. In this country bread is usually made from wheat. If the proteid part of the wheat is left in the flour it will have a brown color. Bread made from this flour is more nutritious but less easily digested than bread made from white flour. Potatoes consist largely of water and starch. They are usually eaten with cream, butter, or gravy and meat, and in this way a supply of starch, fat, and pro- teid is obtained. Green peas, string beans, spinach, and asparagus are examples of other vegetables that are easily digested. Such vegetables are useful chiefly for the salts they contain. Kipe, sound, fresh fruits are of some value as food, because of the sugar and salts in them. Fruit salts are especially good for growing children. 54 PHYSIOLOGY FOE CHILDEEN Food not easily digested. Some articles of food are more easily digested and more nutritious than others. People have to learn by experience what agrees with them, and, if they are wise, they will not eat food that disagrees with them. Pork of any kind, salt meats, salt fish, veal, liver, kidney, goose, and duck are hard to digest. Green corn, radishes, raw celery, onions, tomatoes, carrots, and cucumbers are not easily digested, and contain only a small amount of nourishment. Hot bread, buns, rolls, and cake are hard to digest. Pies, tarts, pastry, nuts, and salads are not easily digested. Unripe or partially decayed fruits should never be eaten. Dried, canned, and preserved fruits, and jellies are not so desirable as fresh ripe fruit. The cooking of food. Most of our food is cooked in some way, in order to make it pleasanter to the taste, or easier to digest. After having been cooked, meat is more tender, and more digestible. Only a small amount of uncooked starch can be digested, but after starchy food has been well cooked the starch grains swell and burst their envelopes, and can then be easily digested. Care is needed in the cooking and serving of food. Every dish or utensil in which it is cooked, DIFFEEENT ARTICLES OF FOOD 55 THE COOKING <5F FOOD. and every dish in which it is served or put away, should be thoroughly clean. Pood should be kept covered as much as possible, to protect it from insects. Every one should learn to cook. Such knowledge is always useful, and often necessary. Artificial drinks. Water is often flavored in different ways to make artificial drinks. All artificial drinks may be divided into two classes, those which contain alcohol, and those which do not. Among those which do not contain alcohol are tea, coffee, cocoa, and chocolate. These drinks are 56 PHYSIOLOGY FOR CHILDREN taken mainly because of their pleasant taste and the agreeable effects they produce. Cocoa and chocolate are more nourishing than either tea or coffee, and if prepared with plenty of milk may be given to children. Tea and coffee are not good drinks for children, and grown people are injured by taking them too strong, or in too large a quan- tity. Rules. A few simple rules in regard to eating should always be observed. 1. We should eat slowly and chew our food well. 2. Food should not be eaten after the feeling of hunger is satisfied. 3. Meals should be taken at regular hours. 4. Nothing should be eaten between meals. 5. The evening meal should be the simplest and plainest meal of the day. 6. No drink should be taken while there is food in the mouth. 7. Ice water should not be taken freely at meal time. Alcohol. In our choice of what we eat and drink we should select what will keep the body in as nearly perfect condition as possible, and avoid what will prevent us from doing our best work. The use of DIFFEEENT AETICLES OF FOOD 57 alcoholic liquor unfits a man for careful and exact work, and for holding positions in which he has charge of the life and property of others. Many companies and business firms will not employ a man who is known to drink, because they are afraid to trust their business to him. The following show that this state- ment is true: WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, PITTSBURG, PA. January 15, 1900. Gentlemen: Replying to yours of the 13th instant, we do not post or publish any rules concerning the use of alcoholic liquors by our employees, nor do we consider such rules at all necessary. We do not knowingly employ for any important position any person known to be a habitual user of alcoholic liquors. If we, unfortunately, find such a person in our employ, we dismiss him. Yours truly, B. H. WARREN, Second Vice- President. NEW YORK CENTRAL & HUDSON RIVER R. R. Co. " The use of intoxicating drink on the road or about the premises of the corporation is strictly forbidden. No one will be employed, or continued in employment, who is known to be in the habit of drinking intoxicating liquor/ 7 E. VAN ETTEN, General Superintendent. 58 PHYSIOLOGY FOE CHILDREN ILLINOIS CENTRAL EAILKOAD COMPANY. ' ' The Company hereby announces that in employment and promotions in its service a preference will be given to persons who are known to be total abstainers ; and under no circum- stances will it tolerate acts of drinking by men on duty, or wearing any part of the Company's uniform." A. W. SULLIVAN, General Superintendent. METROPOLITAN STREET KAILWAY COMPANY, NEW YORK. " Drinking any beer, wine, liquor or intoxicating drink, or entering any drinking place during the hours of duty, or the carrying of any intoxicating drink about the person, or the bringing of same on the premises of the Company will be cause for discharge. The frequenting of drinking places, or the indulgence to excess in intoxicating liquors when oil duty, will be cause for discharge/' OREN ROOT, JR., Assistant to the President. CANADIAN PACIFIC RAILWAY COMPANY.