The laws of health

Preface

It has been my aim in this little book to place before the reader certain rules and suggestions for regulating his mode of living, so that by carrying them out he may maintain his body and his mind in a healthy condition. The book is intended primarily for the older pupils in Elementary Schools, but will, I venture to think, be of use to pupils in Secondary Schools and possibly to adults.

At the commencement of each chapter there is a very brief outline of the structure and working of the particular organs concerned. Details of structure of the various parts of the body have been omitted, and only so much has been included as is necessary to enable the reader to understand the general principles of the action of the different organs and how to keep them in good working order.

Certain subjects have been treated at some length ; for example, the use and abuse of alcohol, the care of the teeth, the value of free ventilation and of exercise, the feeding of infants, the care of the eyes in childhood, tight clothes, smoking, diet, and the necessity for personal cleanliness ; others, such as the details of cooking, are only lightly touched upon.

I am particularly indebted to Miss E. Abadi, B.A., Head-mistress of the Bell Lane School, London, for the

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PREFACE assistance she has given me in the preparation of this volume. Miss Abadi’s experience in the teaching of children enabled her to give me many valuable suggestions throughout the work.

My thanks are also due to Dr. A. C. Stevenson, of University College, London, for drawing four of the figures (4, 8, 9, 11) ; the others have been borrowed from ‘ Physiology for Beginners,’ by Dr. Leonard Hill, to whom and to Mr. Edward Arnold my thanks are due.

DAVID NABARRO.

Hampstead, N.W.

Note. — Teachers desiring an outline course for younger pupils who are not concerned with the physiological basis of the subject are recommended to use only the following parts of the book :

The whole of the first chapter.

The Summaries alone might be used for younger pupils, giving in a succinct and definite form all that is necessary for practical guidance.

Contents

CHAPTER

I. INTRODUCTORY

II. THE BONES OF THE BODY -

Chapter I Introductory

1. The human body is a machine like a steam-engine. Both consist of many parts and joints which require attention and care. Like a steam-engine, the human body can do work, but only when the necessary fuel is supplied to it. The fuel in the case of a steam-engine is coal ; in the case of the human body it is food. Just as an engine will do most work when supplied with the best quality of coal, so the body will work best when fed upon the proper kinds of food. Then we find that in a steam-engine there are certain waste products which are got rid of, such as smoke from the funnel, ashes and clinkers from the furnace, and stale oil from the various joints. So the human body gets rid of waste materials from the lungs, from the skin, from the kidneys, and from the bowel.

2. The comparison may be carried still further. An engine requires a good draught — that is to say, a good current of air — to burn up the fuel completely. Just in the same way, a large supply of pure air is necessary for human beings to keep their lungs and their bodies generally in good working order.

3. What happens to the coal a stoker puts into the fire of his steam-engine ? With the help of the air it is burnt up and much heat is produced. This causes the water to boil in the boiler of the engine and changes it into steam. The steam is made to do work by turning round the wheels of the engine and so making it travel. The fuel, therefore, which is supplied to an engine in the form of coal produces heat. The heat changes water into steam, which does work. In exactly the same way we take in food as fuel, which produces heat and also gives us strength to work. If we had no food given us we should very soon have no strength left to do work ; we should form little heat, and, in fact, should soon die from starvation.

4. Although the human body is like a steam-engine in many ways, yet there are also several important points of difference. In the first place, the human body is very much more complicated in its structure and more delicate in its working than any engine or machine made by man. As we shall see later, it is made up of millions upon millions of cells which are grouped together in different ways to form the tissues and organs of the body. These tissues and organs have their special duties to perform for the good of the body as a whole.

5. Secondly, an engine is made almost entirely of steel, whereas in the human body we find many different substances or tissues, such as bone, muscle or flesh, cartilage or gristle, binding or connective tissue, nerve tissue, and so on. In that respect the body may be compared with a house in which we find different materials, such as wood, plaster, cement, bricks, metal, and glass.

6. Thirdly, you may have a small steam-engine or a large one, but the small one does not grow into a large one. Once the engine is made, it remains the same size as long as it lasts. On the other hand, a new-born baby is a complete human being, but does not remain the same size all through life. During the first twenty years of its existence it grows, so that, when it becomes a man or a woman, it is several times longer and much heavier than when it was born.

7. Fourthly, we have seen that an engine requires fuel, and fuel only, to enable it to do its work properly. On the other hand, the human body must be fed on something else besides fuel-forming food, so that it may go on working satisfactorily. It requires a substance called nitrogen , which is present in certain foods — especially meat, peas, and beans— to make up for the waste of the tissues which is always going on. Such foods are also required in great quantity by children who are growing, because they help to build up bone, flesh, and many of the important tissues of the body.

8. Lastly— -and here we come to the most important difference between man and an engine — man not only works, but has the power of thinking and of acting accordingly. In order to think properly it is necessary for the body, and especially the brain, to be in a sound and healthy condition.

9. What, then, is meant by being healthy ? In perfect health there is no pain in any part of the body, such as headache, toothache, stomach-ache, or any

1—2 other ache ; nor are there any other unusual feelings anywhere, such as dryness or bad taste in the mouth, sickness, or ‘ pins and needles ’ in the hands or feet. There are no swellings or unusual appearances, but every part of the body looks sound and well formed. The appetite is good, we enjoy our food, and all the functions of the body are properly carried on. The skin acts well, and is of a good, healthy colour; the kidneys and the bowels, and all other parts of the body, do their work satisfactorily. We feel well, active, and ready to work both with the body and with the brain. Lastly, in perfect health we sleep well and soundly, and get up every morning refreshed and ready to do the day’s work.

10. I think you will say that it is not often one meets anybody who enjoys all the blessings I have just mentioned, and that, therefore, very few people enjoy perfect health. That is quite true, and most people consider that they are healthy although they may have slight aches and pains, or unpleasant feelings sometimes. Well, then, although it may be very difficult for us to be and remain perfectly healthy, yet we should always try to be as healthy as we can, for there is no greater blessing than good health. We only find this out when we have lost it and are ill. Then we know how pleasant it is to be well and healthy — to be able to join in the work and the play of our fellow-creatures.

11. You cannot be expected to know, without being told, how to keep healthy, and it is the purpose of this little book to tell you how to live so as to keep your body and your mind in a state of good health. Here I shall give you a few general hints only.

12. In the first place, try to lead a regular life ; eat regularly and not too quickly ; work regularly, but do not overwork ; take proper recreation, especially exercise in the open air, whenever possible, and give the brain rest by taking a proper amount of sleep. Secondly, let your food be plain, nourishing, and wholesome. Take sufficient of it, but not too much. Avoid harmful things, and, above all, avoid taking too much alcohol in the form of beer, wine, or spirits. Thirdly, breathe as much pure air as you can, and see to the proper ventilation of your rooms and houses. At the same time avoid draughts, chills, and getting wet. Fourthly, dress properly, according to the state of the weather and the season of the year. Fifthly, take proper care of your bodies, paying particular attention to personal cleanliness. Also see that your house is always kept in a sweet and clean condition. Avoid injuries to your bodies, for often a slight injury may lead to serious and lasting illness, and possibly deformity. Lastly, avoid too much of anything, for that is always harmful : too much eating, especially meat ; too much drinking, especially beer, spirits, and tea ; too much exercise and too much work ; too much smoking ; and, I would add, do not worry more than is necessary, for nothing makes a person old before his time quicker than worry.

13. An engine - driver, to keep his steam-engine working properly and at its best, must know something about the construction of his engine and how it works. Unless he does so, should any slight accident happen, he will be unable to set matters right. In the same way, before you can understand how to keep the body in a state of good health, you must be told something about the wonderful construction and working of its different parts. I do not intend to tell you many details, because you can read them for yourselves in any book on physiology. I intend to tell you only just so much as is necessary for you to understand the various rules I recommend you to follow. If you carry out these rules carefully I am sure you will lead healthy and happy lives.

Chapter II The Bones Of The Body

14. When a big warehouse or shop is being built, strong iron beams called girders are put up and joined to one another. The bricks, wood, and other materials are added later to make the outside walls and the different rooms, doors, windows, and other parts of the building which help to make it complete. What is the use of these iron girders ? In the first place, they give firmness and support to the whole building ; secondly, they protect the rooms inside the building from injury such as might happen from wind; and, thirdly, the walls and floors of the different rooms are joined on to these girders, which may therefore be said to serve as points of attachment for the various parts inside the building ; lastly, we may add that, when the building is finished, the girders are quite hidden though we know they are there.

15. We find much the same state of things in the human body. Inside the body, and quite hidden from view under ordinary conditions, we have a large number of bones all joined together to form what is called the skeleton of the body. These bones are very hard and strong, and have the same use as the girders in a build,- ing. They give firmness and support to the whole body, they protect the parts inside, and they serve as points of attachment for the various muscles of the body by which we move. There is one great difference between the girders of a building and the bones in our body. Girders are strongly fastened together so that no movement can take place between them. The bones of our body are also fastened together, only loosely, so that we can move one bone on the other ; if it were not for this we should be unable to use the fingers, arms, hands, legs, or, indeed, any part of the body. The bands which tie bones together are known as ligaments. The ends of bones which are thus joined by ligaments are called joints. Sometimes in disease the bones become tightly fixed together at the joints in the fingers, wrists, arms, shoulders, legs, or back.

16. The bones of the body forming the skeleton may be divided into three groups : (1) The skull, or bones of the head ; (2) the bones of the body proper, or the trunk ; and (8) the bones of the limbs (the arms and legs).

(1) The skull, or brain-box, is a strong box made up of twenty-two bones. It consists of two main parts. The larger, smooth, hollow part at the top and back contains that important structure, the brain. This part of the skull is very strong so as to protect the brain from injury. The lower and front part of the skull is called the face, and contains the holes for the eyes and nose and the two jaw-bones which carry the teeth. In a grown-up person all the bones of the skull are firmly joined together except the lower jaw-bone, which has a movable joint to enable us to eat and talk. In a young child the skull-bones are softer, especially where they are joined together.

(2) In the body proper, or trunk, we have the ‘ backbone ’ or spine, which is made up of twenty- six bones, placed one above the other and joined together by strong ligaments. These bones can move a little on one another and allow us to bend or straighten the back. The skull is jointed on the top of the backbone so that we can move our head in almost any direction.

o p g

Fig. 1. — The Skull.

A, b, c, D, The part of the skull enclosing the brain ; e, hole leading to drum of ear ; f, joint of lower jaw-bone ; g. h, lower and upper jaw-bones ; j, cheek-bone ; k, nose-bone ; l, socket of eye ; m, incisor teeth; n, canine ; o, bicuspids ; p, molars.

The upper part of the body is called the chest or thorax. In front there is the long flat breast-bone, and at the sides of the chest are twenty-four ribs, twelve on each side. The ribs are joined to the spine behind, and to the breast-bone in front. Some of the lower ribs do not quite reach the breast-bone, but hang loose. The bony cage of the chest, formed by the spine, ribs, and breast-bone, protects the heart and lungs which are inside the chest.

(8) Let us now consider the bones of the limbs. Each arm is divided into the upper arm, forearm, wrist, hand, and fingers. In the upper arm there is one strong bone with a large knob-like end which is jointed to the shoulder-blade. This joint, the shoulder -joint, is a very free one, and allows the arm to be moved in any direction. In the forearm are two thinner bones, which are jointed to the upper-arm bone at the elbow-joint. The wrist is made up of a number of small bones. In the palm of the hand there are five long, thin bones, one for the thumb and one for each finger. Each finger has three small Jinger-bones ; the thumb has only two. The arm is joined to the body by means of the shoulder - girdle. The shoulder-girdle consists of the collar-bone and the shoulder - blade. The collar - bones are the curved, rounded bones just above the ribs in front of the neck. The shoulder-blades are the flat bones at the back to which the arm-bones are jointed. Sit up straight and throw the shoulders well back; this brings the shoulder-blades nearer together and makes them stand out more from the body. Stand in front of a looking-glass and shrug the shoulders, you will then see the collar-bones more distinctly and will also be able to make out their shape.

Each leg is divided into the thigh, leg proper, ankle, heel, foot, and toes. In the thigh there is the long and very strong thigh-bone, the longest and strongest bone in the body. Above, it has a large round head which fits into a cup-like hollow in the hip-bone, to which it is loosely jointed by strong ligaments. The hip-joint is not so free as the shoulder-joint,, but still it allows the.

A

Fig. 2.— The Skeleton.

a, Skull ; B, lower jaw ; c, n, p, bones of the spine ; d, collar-bone ; E, shoulder-blade ; f, breast-bone ; g, upper-arm bone ; H, i, forearmbones'; j, wrist-bones ; k, hand-bones ; l, finger-bones ; m, lowest ribs ; o, hip-bone ; q, thigh-bone ; r, knee-cap ; s,. t, leg-bones ; tr, ankle-bones ; v,. feet-bones ; x> toe-bones.

thigh to be moved in any direction. The lower end of the thigh-bone is broad, and rests upon the broad top of shin-bone, forming the knee-joint. In front of the knee-joint, as yon may easily feel for yourself when standing, there is a flat, round bone called the knee-cap. This bone sometimes snaps across when people slip down. It is a serious accident, because when this bone is broken we are unable to walk. If the parts of the broken knee-cap do not join properly after the accident, the leg will be useless, and the patient unable to walk properly ever after.

The bones forming the knee-joint are joined together by very strong ligaments which prevent the bones being displaced or dislocated. The shin-bone is much the stronger bone in the lower part of the leg, but there is a thin bone which runs down with it all the way to the ankle. At the ankle there is a bony swelling on each side, the inner one being the end of the shin-bone, the outer one the end of the slender bone of the leg. In the foot there are several bones, irregular in shape, the largest being the heel-bone, which helps to form the heel. In front of these irregular bones there are five long, thin bones, just like those in the palm of the hand. Lastly, each toe has three small toe-bones , and the big toe only two, just as in the case of the fingers and thumb.

The legs are joined to the body by means of the hip-bones. When you place the 4 hands on hips,’ the hands rest upon the upper edge of the hip-bones. These are two very strong, irregularly - shaped bones, which are joined together in front at the lowest part of the trunk. Behind, they are very firmly bound to the spine by means of strong ligaments. The two hip-bones and the spine- bone to which they are joined, together form the

IB pelvic girdle, which is very strong as it has to bear the whole weight of the body above. The thigh-bones are jointed to the hip-bones, but the legs cannot be moved about so freely as the arms. That is because the pelvic girdle is firmly fixed to the trunk, whereas the shoulder-blades can slide up and down and so enable us to move the arms about freely.

17. The long bones of the body, such as the thigh-bones, consist of a very hard, dense substance arranged like a hollow tube. Inside this tube is a fatty substance called the marrow At the ends, where they become broader to form the joints, the bones are no longer like a hollow tube nor so hard, but spongy inside with a thin shell of hard bone outside.

The smaller flat bones, such as the ribs, breast-bone, etc., are like the spongy ends of the long bones in structure.

18. Bone is made up of one part of animal matter and two parts of mineral matter. This can be proved by means of two simple experiments. Take a

Fig. 3. — Shin-bone Sawn in Half.

1, 2, Spongy bone ; 3, hard, dense bone ; 4, marrow

cavity ; 5, layer of gristle at the growing part of the bone ; 7, gristle covering the joint surface of the bone.

piece of fresh bone and weigh it carefully. Put it in a jar of weak acid (‘ spirits of salts ’ and water), and leave it in for a fortnight or more. At the end of that time remove the bone, wash it in water, dry it and weigh again. The bone will have lost two-thirds of its weight, because all the mineral matter is dissolved out by the acid. The mineral matter gives to bone its hardness, and therefore the animal matter, which is left after dissolving out the mineral matter, is quite soft and easily bent. The animal matter is like gristle and makes the bone tough and elastic.

19. Next, take another piece of fresh bone, weigh it as before, and hold it over a bright red fire in an iron spoon. After a time the bone turns quite white : all the animal matter has been burnt away and only the mineral matter is left. After letting the bone-ash cool down, weigh it. The bone will have lost only one-third of its weight, which was that of the animal matter in it at the start. The mineral matter of bone consists chiefly of salts of lime. Children’s bones have more animal and less mineral matter in them than the bones of adults. This makes them tougher and less brittle than the bones of grown-up people. In cases of accident, when the bones of older people would be broken right across, those of children often only bend or are partially broken. Thus if you try to bend a piece of wood or dried twig of a tree it will snap and break right across ; if you do the same to a fresh, green twig it will bend and then break partly but not right across. The bones of children generally break in this way, and it is known as a ‘ greenstick ’ break or fracture.

20. A child during its growth requires in proportion more food than does a grown-up person. Like an adult, a child has to supply fuel to keep up the heat of the body and to do work, as well as to replace the wear and tear of the tissues. But in addition to this, the child’s body grows and gets bigger every day, and therefore requires an extra supply of food. To build up good, sound, strong bones a healthy, growing infant requires a liberal supply of nitrogen-containing or proteid food, of mineral food, and of fat. It requires also a certain amount of sugar during the first year of its life, but less than it does later on.* If an infant is fed on too little proteid and mineral food its bones will not be strong and healthy. There will be too little mineral matter in the bones, which are therefore softer than they should be. A little later, when the child begins to stand and to toddle about, the weight of its body will make the bones bend, and the legs will become crooked. It will then get all the signs of the disease called rickets. Not only the legs but also the bones of the arms, chest, and

* Sugar and starchy food are known as carbohydrate food, because they contain the elements carbon, hydrogen, and oxygen. Such foods are fuel, like the coal used for the steam-engine, and are work-producers . During its first year a child does very little work because it sleeps most of the day and night. A baby, therefore, does not want so much of these foods in proportion as an adult.

The most important mineral foods a baby requires are phosphate of lime and phosphate of potash. The phosphate of lime is necessary for the proper growth and hardness of the bones and teeth. The phosphate of potash is necessary for the formation of good healthy muscles and blood. These mineral foods are present in meat and milk in a form which is easily absorbed by the blood. Therefore, by feeding a child on good milk and, as it grows older, also on meat, it gets not only the necessary proteid or nitrogenous food, but also the necessary mineral salts.

head may be soft and become bent. It is a serious thing if the ribs become soft in rickets, because they bend inwards and make the chest out of shape. If the child should get a slight cold on its chest, it would always be liable to get serious lung disease which might even cause death.

21. Human (mother’s) milk is the natural and only necessary food for a baby until it is nine or ten months old. It contains all these foods (proteid, mineral, fat, and sugar) in the proper quantities for the healthy growth of the baby’s bones and other tissues. Cow’s milk, prepared as we shall learn later, will do almost as well.

22. We have seen that children’s bones are softer than those of grown-up people. We must, therefore, take care that the bones do not get bent, otherwise they may remain bent all through life. Rickets, which is caused by bad feeding, may lead to bending of the bones and so give rise to crooked legs and arms and badlyformed chests in children. These can all be prevented by giving babies a proper and sufficient supply of food. The head-bones of children are always soft, and particularly so in rickets. A child’s head must, therefore, be well protected from injuries, such as blows or falls. Young girls and boys should not be allowed to carry a baby, large parcels, or other heavy weights. Children who constantly carry heavy weights may become deformed owing to the spine becoming curved. Violence to any part of the body may cause the bones to break. If the bone in a limb is broken, the limb is altered in shape and cannot be moved or used until the bone is ‘set ’ and properly joined.

23. People of all ages should avoid prolonged and undue pressure on any of the bones, as this may lead to serious results. (1) The organs, if pressed upon, cannot do their work properly ; and (2) prolonged pressure leads to loss of proper shape of the body. Thus, girls should never press in their chests by the use of tight stays. Stays do a great deal of harm to children as well as to grown-up women, especially if they are drawn in too tightly about the waist. Tight stays prevent proper movement of the ribs during breathing. People who wear tight stays never get enough air into the lungs, which is so necessary for good health.

24. Tight lacing also presses the lungs, heart, liver, and stomach out of their proper position, and so interferes with the working of those organs. The result is pain, discomfort after eating, bad circulation of the blood through the heart and lungs, and indigestion of food. Tight bands round the neck or wrists and tight braces and garters should also be avoided, as they all interfere with the circulation and with the proper working of various parts of the body.

25. Particular attention must be given to the feet. Tight, ‘ smart-looking ’ boots with pointed toes and high heels should never be worn. Boots should always be comfortably loose (but not too large), with broad toes and low heels ; the feet will then keep their proper shape, which nowadays we see only in the case of little babies who have never worn boots or shoes. By wearing properly-shaped boots or shoes the toes will not be pressed over one another, and there will be no blisters, corns or bunions on the feet.

26. Yon should always remember to sit up straight, with the shoulders well back and the head erect, especially at school in your desk. When writing, do not press the chest against the desk, or sit crooked or bend the body forward over the desk. If you often sit crooked, or stand with * round shoulders ’ or with the weight of the body on one leg, by which the pelvic girdle is lowered on that side, the spine and back may become bent and you may remain crooked for life.

27. Our bones may be joined together in one of three ways : First, they may be tightly fixed by parts of one bone dove-tailing into the other bone, as in the case of the bones of the skull ; secondly, the bones may be joined together, but not quite tightly, so that they can move a little. This is seen best in the bones which make up the spine or backbone. Each bone in the spine can move a little on the bone above and below it. Through this movement we are able to bend the neck forwards or backwards or from side to side, also to bend the back, as in playing leap-frog ; thirdly, the bones may be joined so loosely that we are able to move them a great deal. The shoulder, elbow, wrist, hip, knee, ankle and finger joints are all examples of this kind of joint.