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diff --git a/17367.txt b/17367.txt new file mode 100644 index 0000000..2afdb3b --- /dev/null +++ b/17367.txt @@ -0,0 +1,5532 @@ +Project Gutenberg's First Book in Physiology and Hygiene, by J.H. Kellogg + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: First Book in Physiology and Hygiene + +Author: J.H. Kellogg + +Release Date: December 21, 2005 [EBook #17367] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK FIRST BOOK IN PHYSIOLOGY *** + + + + +Produced by Suzanne Lybarger, Janet Blenkinship, Brian +Janes and the Online Distributed Proofreading Team at +https://www.pgdp.net + + + + + + + + [Illustration: PLATE I THE CIRCULATION] + + + + + FIRST BOOK + + IN + + PHYSIOLOGY AND HYGIENE + + BY + + J.H. KELLOGG, M.D. + + MEMBER OF THE AMERICAN MEDICAL ASSOCIATION, THE AMERICAN PUBLIC HEALTH + ASSOCIATION, SOCIETE D'HYGIENE OF FRANCE, BRITISH AND AMERICAN + ASSOCIATIONS FOR THE ADVANCEMENT OF SCIENCE, MICHIGAN + STATE BOARD OF HEALTH, ETC. + + _ILLUSTRATED_ + + NEW AND REVISED EDITION + + NEW YORK CINCINNATI CHICAGO + + AMERICAN BOOK COMPANY + + Copyright, 1887, by HARPER & BROTHERS. + + Copyright, 1888, by HARPER & BROTHERS + + _All rights reserved._ + + W.P. 7 + + + + +TO THE TEACHER. + + +This book is intended for children. The special objects which the author +has aimed to accomplish in the preparation of the work have been: + +1. To present as fully as possible and proper in a work of this +character a statement of the laws of healthful living, giving such +special prominence to the subject of stimulants and narcotics as its +recognized importance and the recent laws relating to the study of this +branch of hygiene demand. + +2. To present in a simple manner such anatomical and physiological facts +as shall give the child a good fundamental knowledge of the structure +and functions of the human body. + +3. To present each topic in such clear and simple language as to enable +the pupil to comprehend the subject-matter with little aid from the +teacher; and to observe in the manner of presentation the principle that +the things to be studied should be placed before the mind of the child +before they are named. A natural and logical order has been observed in +the sequence of topics. Technical terms have been used very sparingly, +and only in their natural order, and are then fully explained and their +pronunciation indicated, so that it is not thought necessary to append a +glossary. + +4. To present the subjects of Physiology and Hygiene in the light of +the most recent authentic researches in these branches of science, and +to avoid the numerous errors which have for many years been current in +the school literature of these subjects. + +There is no subject in the presentation of which object-teaching may be +employed with greater facility and profit than in teaching Physiology, +and none which may be more advantageously impressed upon the student's +mind by means of simple experimentation than the subject of Hygiene. +Every teacher who uses this book is urgently requested to supplement +each lesson by the use of object-teaching or experiments. A great number +of simple experiments illustrative of both Physiology and Hygiene may be +readily arranged. Many little experiments are suggested in the text, +which should invariably be made before the class, each member of which +should also be encouraged to repeat them at home. + +It is also most desirable that the teacher should have the aid of +suitable charts and models. + +In conclusion, the author would acknowledge his indebtedness for a large +number of useful suggestions and criticisms to several medical friends +and experienced teachers, and especially to Prof. Henry Sewall, of the +University of Michigan, for criticisms of the portions of the work +relating to Physiology. + + + + + CONTENTS. + + CHAPTER PAGE + + TO THE TEACHER iii + + I. THE HOUSE WE LIVE IN 1 + + II. A GENERAL VIEW OF THE BODY 5 + + III. THE INSIDE OF THE BODY 7 + + IV. OUR FOODS 11 + + V. UNHEALTHFUL FOODS 14 + + VI. OUR DRINKS 19 + + VII. HOW WE DIGEST 27 + + VIII. DIGESTION OF A MOUTHFUL OF BREAD 35 + + IX. BAD HABITS IN EATING 39 + + X. A DROP OF BLOOD 46 + + XI. WHY THE HEART BEATS 48 + + XII. HOW TO KEEP THE HEART AND THE BLOOD HEALTHY 56 + + XIII. WHY AND HOW WE BREATHE 63 + + XIV. HOW TO KEEP THE LUNGS HEALTHY 75 + + XV. THE SKIN AND WHAT IT DOES 81 + + XVI. HOW TO TAKE CARE OF THE SKIN 88 + + XVII. THE KIDNEYS AND THEIR WORK 91 + + XVIII. OUR BONES AND THEIR USES 93 + + XIX. HOW TO KEEP THE BONES HEALTHY 100 + + XX. THE MUSCLES, AND HOW WE USE THEM 105 + + XXI. HOW TO KEEP THE MUSCLES HEALTHY 109 + + XXII. HOW WE FEEL AND THINK 115 + + XXIII. HOW TO KEEP THE BRAIN AND NERVES HEALTHY 126 + + XXIV. BAD EFFECTS OF ALCOHOL UPON THE BRAIN AND + NERVES 130 + + XXV. HOW WE HEAR, SEE, SMELL, TASTE; AND FEEL 138 + + XXVI. ALCOHOL 154 + + QUESTIONS FOR REVIEW 170 + + + + +FIRST BOOK +OF +PHYSIOLOGY AND HYGIENE. + + + + +CHAPTER I. + +THE HOUSE WE LIVE IN. + + +~1. Object of this Book.~--The object of this book is to tell the little +boys and girls who read it about a wonderful house. You have all seen +some very beautiful houses. Perhaps they were made of brick or stone, +with fine porches, having around them tall shade trees, smooth lawns, +pretty flower-beds, walks, and sparkling fountains. + +~2.~ Perhaps some of you live in such a house, or have visited some +friend who does. If so, you know that the inside of the house is even +more beautiful than the outside. There are elegant chairs and sofas in +the rooms, rich carpets and rugs on the floors, fine mirrors and +beautiful pictures upon the walls--everything one could wish to have in +a house. Do you not think such a house a nice one to live in? + +~3. The Body is Like a House.~--Each of us has a house of his own which +is far more wonderful and more curious than the grandest palace ever +built. It is not a very large house. It has just room enough in it for +one person. This house, which belongs to each one of us, is called the +body. + +~4. What is a Machine?~--Do you know what a machine is? Men make +machines to help them work and to do many useful things. A wheelbarrow +or a wagon is a machine to carry loads. A sewing-machine helps to make +garments for us to wear. Clocks and watches are machines for keeping +time. + +~5. A Machine has Different Parts.~--A wheelbarrow has a box in which to +carry things, two handles to hold by, and a wheel for rolling it along. +Some machines, like wheelbarrows and wagons, have but few parts, and it +is very easy for us to learn how they work. But there are other +machines, like watches and sewing-machines, which have many different +parts, and it is more difficult to learn all about them and what they +do. + +~6. The Body is Like a Machine.~--In some ways the body is more like a +machine than like a house. It has many different parts which are made +to do a great many different kinds of work. We see with our eyes, hear +with our ears, walk with our legs and feet, and do a great many things +with our hands. If you have ever seen the inside of a watch or a clock +you know how many curious little wheels it has. And yet a watch or a +clock can do but one thing, and that is to tell us the time of day. The +body has a great many more parts than a watch has, and for this reason +the body can do many more things than a watch can do. It is more +difficult, too, to learn about the body than about a watch. + +~7.~ If we want to know all about a machine and how it works, we must +study all its different parts and learn how they are put together, and +what each part does. Then, if we want the machine to work well and to +last a long time, we must know how to use it and how to take proper care +of it. Do you think your watch would keep the time well if you should +neglect to wind it, or if you should break any of its wheels? + +~8.~ It is just the same with the human machine which we call the body. +We must learn its parts, and what they are for, how they are made, how +they are put together, and how they work. Then we must learn how to take +proper care of the body, so that its parts will be able to work well +and last a long time. + +~9.~ Each part of the body which is made to do some special kind of work +is called an _organ_. The eye, the ear, the nose, a hand, an arm, any +part of the body that does something, is an organ. + +~10.~ The study of the various parts of the body and how they are put +together is _anatomy_ (a-nat'-o-my). The study of what each part of the +body does is _physiology_ (phys-i-ol'-o-gy). The study of how to take +care of the body is _hygiene_ (hy'-jeen). + + +SUMMARY. + +1. The body is something like a house. It has an outside and an inside; +it has hollow places inside of it, and there are many wonderful things +in them. + +2. The body is also like a wonderful machine. + +3. It is necessary to take good care of the body in order to keep it +well and useful, just as we would take good care of a machine to keep it +from wearing out too soon. + +4. The body has many different parts, called organs, each of which has +some particular work to do. + +5. In learning about the body, we have to study anatomy, physiology, and +hygiene. + +6. The study of the various parts of the body, how they are formed and +joined together, is anatomy. Physiology tells us what the body does, +hygiene tells us how to take care of it. + + + + +CHAPTER II + +A GENERAL VIEW OF THE BODY. + + +~1. Parts of the Body.~--What do we call the main part of a tree? The +trunk, you say. The main part of the body is also called its _trunk_. +There are two arms and two legs growing out of the human trunk. The +branches of a tree we call limbs, and so we speak of the arms and legs +as _limbs_. We sometimes call the arms the _upper extremities_, and the +legs the _lower extremities_. At the top of the trunk is the head. + +~2. Names of the Parts.~--Now let us look more closely at these +different parts. As we speak the name of each part, let each one touch +that part of himself which is named. We will begin with the head. The +chief parts of the head are the _skull_ and the _face_. The _forehead_, +the _temples_, the _cheeks_, the _eyes_, the _ears_, the _nose_, the +_mouth_, and the _chin_ are parts of the face. + +~3.~ The chief parts of the trunk are the _chest_, the _abdomen_ +(ab-do'-men), and the _backbone_. The head is joined to the trunk by the +_neck_. + +~4.~ Each arm has a _shoulder_, _upper-arm_, _fore-arm_, _wrist_, and +_hand_. The _fingers_ are a part of the hand. + +~5.~ Each leg has a _hip_, _thigh_, _lower leg_, _ankle_, and _foot_. +The _toes_ are a part of the foot. + +~6.~ Our hands and face and the whole body are covered with something as +soft and smooth as the finest silk. It is the _skin_. What is it that +grows from the skin on the head? and what at the ends of the fingers and +the toes? We shall learn more about the skin, the hair, and the nails in +another lesson. + +~7.~ The body has two sides, the right side and the left side, which are +alike. We have two eyes, two ears, two arms, etc. We have but one nose, +one mouth, and one chin, but each of these organs has two halves, which +are just alike. + + +SUMMARY. + +1. The body has a head and trunk, two arms, and two legs. + +2. The parts of the head are the skull and face. The forehead, temples, +cheeks, eyes, ears, nose, mouth and chin are parts of the face. + +3. The parts of the trunk are, the chest, abdomen, and backbone. The +neck joins the head and trunk. + +4. Each arm has a shoulder, upper-arm, fore-arm, wrist, and hand. The +fingers belong to the hand. + +5. Each leg has a hip, thigh, lower leg, ankle, and foot. The toes +belong to the foot. + +6. The whole body is covered by the skin. + +7. The two sides of the body are alike. + + + + +CHAPTER III. + +THE INSIDE OF THE BODY. + + +~1.~ Thus far we have taken only a brief look at the outside of the +body, just as if we had looked at the case of a watch, and of course we +have found out very little about its many wonderful parts. Very likely +you want to ask a great many questions, such as, How does the inside of +the body look? What is in the skull? What is in the chest? What is in +the abdomen? Why do we eat and drink? Why do we become hungry and +thirsty? What makes us tired and sleepy? How do we keep warm? Why do we +breathe? How do we grow? How do we move about? How do we talk, laugh, +and sing? How do we see, hear, feel, taste, and smell? How do we +remember, think, and reason? All these, and a great many more +interesting questions, you will find answered in the following lessons, +if you study each one well. + +~2.~ When we study the inside of the body, we begin to understand how +wonderfully we are made. We cannot all see the inside of the body, and +it is not necessary that we should do so. Many learned men have spent +their whole lives in seeking to find out all about our bodies and the +bodies of various animals. + +~3. The Bones.~--If you take hold of your arm, it seems soft on the +outside; and if you press upon it, you will feel something hard inside. +The soft part is called _flesh_. The hard part is called _bone_. If you +wish, you can easily get one of the bones of an animal at the butcher's +shop, or you may find one in the fields. + +~4. The Skeleton.~--All the bones of an animal, when placed properly +together, have nearly the shape of the body, and are called the +_skeleton_ (skel'-e-ton). The skeleton forms the framework of the body, +just as the heavy timbers of a house form its framework. It supports all +the parts. + +~5. The Skull.~--The bony part of the head is called the _skull_. In the +skull is a hollow place or chamber. You know that a rich man often has a +strong room or box in his fine house, in which to keep his gold and +other valuable things. The chamber in the skull is the strong-room of +the body. It has strong, tough walls of bone, and contains the _brain_. +The brain is the most important, and also the most tender and delicate +organ in the whole body. This is why it is so carefully guarded from +injury. + +~6. The Backbone.~--The framework of the back is called the _backbone_. +This is not a single bone, but a row of bones arranged one above +another. Each bone has a hole through it, about as large as one of your +fingers. A large branch from the brain, called the _spinal cord_, runs +down through the middle of the backbone, so that the separate bones look +as if they were strung on the spinal cord, like beads on a string. + +~7. The Trunk.~--The trunk of the body, like the skull, is hollow. Its +walls are formed partly by the backbone and the ribs and partly by +flesh. A fleshy wall divides the hollow of the trunk into two parts, an +upper chamber called the _chest_, and a lower called the _abdomen_. + +~8. The Lungs and Heart.~--The chest contains a pair of organs called +the _lungs_, with which we breathe. It also contains something which we +can feel beating at the left side. This is the _heart_. The heart lies +between the two lungs, and a little to the left side. + +~9. The Stomach and Liver.~--In the abdomen are some very wonderful +organs that do different kinds of work for the body. Among them are the +_stomach_, the _bowels_, and the _liver_. There are, also, other organs +whose names we shall learn when we come to study them. + +~10. Care of the Body.~--We have only begun to study the beautiful +house in which we live, and yet have we not learned enough to show us +how great and wise is the Creator who made us and all the wonderful +machinery within our bodies? If some one should give you a beautiful +present, would you treat it carelessly and spoil it, or would you take +good care of it and keep it nice as long as possible? Ought we not to +take such care of our bodies as to keep them in that perfect and +beautiful condition in which our kind and good Creator gave them to us? + + +SUMMARY. + +1. The body has a framework, called the skeleton. + +2. The skeleton is made up of many different parts, each of which is +called a bone. + +3. The bones are covered by the flesh. + +4. The bones of the head form the skull, which is hollow and contains +the brain. + +5. A row of bones arranged in the back, one above another, forms the +backbone. The backbone has a canal running through it lengthwise, in +which lies the spinal cord. + +6. The trunk is hollow, and has two chambers, one called the cavity of +the chest, and the other the cavity of the abdomen. + +7. The chest contains the two lungs and the heart. + +8. The abdomen contains the stomach, liver, and many other very +important organs. + +9. Is it not our duty to take good care of our bodies as we would of +some nice present from a friend? + + + + +CHAPTER IV. + +OUR FOODS. + + +~1.~ We all know very well that if we do not eat we shall rapidly lose +in weight, and become very weak and feeble. Did you ever think how much +one eats in the course of a lifetime? Let us see if we can figure it up. +How much do you suppose a boy eats in a day? Let us say two pounds. How +much does he eat in a year? There are three hundred and sixty-five days +in a year; 365 multiplied by 2 equals 730. So a boy eats a good many +times his own weight in a year. How much would a person eat in fifty +years? + +~2.~ Our bodies are composed of what we eat. If we eat bad food, our +bodies will be made out of poor material, and will not be able to do +their work well. So you see how important it is to learn something about +our foods. We ought to know what things are good for us to eat, and what +will do us harm. + +~3. Foods and Poisons.~--Foods are those substances which nourish the +body and keep it in good working order. + +~4.~ Our foods are obtained from both animals and plants. All food +really comes from plants, however, since those animals which we +sometimes use as food themselves live upon the vegetables which they +eat. For example, the ox and the cow eat grass and furnish us beef and +milk. Chickens eat corn and other grains, and supply us with eggs. + +~5.~ The principal animal foods are milk, cheese, eggs, and the +different kinds of flesh--beef, mutton, pork, fish, fowl, and wild game. + +We obtain a great many more kinds of food from plants than from animals. +Most plant foods are included in three classes--_fruits_, _grains_, and +_vegetables_. + +~6.~ _Fruits_ are the fleshy parts of plants which contain the seeds. +Our most common fruits are apples, pears, peaches, plums, cherries, and +various kinds of nuts. Perhaps you know of some other kinds of fruits +besides those mentioned. Your teacher will tell you that tomatoes, +watermelons, and pumpkins are really fruits, though they are not +generally so called. + +~7.~ The seeds of grass-like plants are known as _grains_, of which we +have wheat, rye, barley, corn, and rice. There are a few seeds that grow +in pods, such as pease and beans, which somewhat resemble grains. + +~8.~ We eat the leaves, stems, or roots of some plants, as cabbages, +celery, turnips, and potatoes. Foods of this kind are called +_vegetables_. + +~9.~ There are other things, which, if we eat or drink them, will make +us sick or otherwise do us harm. These are called _poisons_. Only such +food as is pure and free from poisons is good or safe for us to use. + +~10. Narcotics and Stimulants.~--There are a number of substances known +as narcotics and stimulants, which, from their effects upon the body, +may be classed as poisons. Tobacco, opium, alcohol, and chloral are +included in this class. Death has often been caused by taking small +quantities of any of these poisonous drugs. We shall learn more of the +effects of tobacco and alcohol in future lessons. + + +SUMMARY. + +1. Our bodies are made of what we eat. + +2. Things which will help us to grow strong and well, if we eat them, +are foods. + +3. We get foods from plants and animals. + +4. There are several kinds of animal foods, and three classes of plant +foods--fruits, grains, and vegetables. + +5. Things which make us sick when we eat them, are poisons. + + + + +CHAPTER V. + +UNHEALTHFUL FOODS. + + +~1.~ Most persons eat many things which are not good for them. Some +people do not stop to think whether what they eat is good for them or +likely to do them harm. Sometimes, without knowing it, we eat things +which are harmful to us. Do you not think that we should try to learn +what is good to eat and what is not good, and then be very careful not +to eat anything which is likely to do us harm? + +~2. Diseased Foods.~--When a person is sick, he is said to be diseased. +Animals are sometimes sick or diseased. Vegetables are also sometimes +diseased. Animals and vegetables that are diseased are not good for +food. Dishonest men, however, sometimes sell them to those who do not +know that they are unfit to be eaten. + +~3.~ Pork, the flesh of the hog, is more likely to be diseased than any +other kind of animal food. + +~4.~ Beef and mutton may be diseased also. Sheep and cattle are +sometimes sick of diseases very much like those which human beings +have. Meat which is pale, yellowish, or of a dark red color, is +unhealthful, and should not be eaten. Meat should never be eaten raw. It +should always be well cooked. + +~5. Unripe Foods.~--Most vegetable foods are unfit to be eaten when +green or unripe, especially if uncooked. Sometimes persons are made very +sick indeed by eating such articles as green apples or unripe peaches. + +~6. Stale or Decayed Foods.~--Food which has been allowed to stand until +it is spoiled, or has become _stale_, _musty_, or _mouldy_, such as +mouldy bread or fruit, or tainted meat, is unfit to be eaten, and is +often a cause of very severe sickness. Canned fish or other meats spoil +very quickly after the cans are opened, and should be eaten the same +day. + +~7. Adulterated Foods.~--Many of our foods are sometimes spoiled or +injured by persons who put into them cheap substances which are harmful +to health. They do this so as to make more money in selling them. This +is called _adulteration_. The foods which are most likely to be injured +by adulteration are milk, sugar, and butter. + +~8.~ Milk is most often adulterated by adding water, though sometimes +other things are added. Sometimes the water is not pure, and people are +made sick and die. The adulteration of milk or any other food is a very +wicked practice. + +~9.~ Butter is sometimes made almost wholly from lard or tallow. This is +called _oleomargarine_ or _butterine_. If the lard or tallow is from +diseased animals, the false butter made from it may cause disease. + +~10.~ A great deal of the sugar and syrups which we buy is made from +corn by a curious process, which changes the starch of the corn into +sugar. Sugar which has been made in this way is not so sweet as cane +sugar, and is not healthful. + +~11. Condiments or Seasonings.~--These are substances which are added to +our food for the purpose of giving to it special flavors. Condiments are +not foods, because they do not nourish the body in any way, and are not +necessary to preserve it in health. + +~12.~ The most common condiments are, mustard, pepper, pepper-sauce, +ginger, cayenne-pepper, and spices. All these substances are irritating. +If we put mustard upon the skin, it will make the skin red, and in a +little time will raise a blister. If we happen to get a little pepper in +the eye, it makes it smart and become very red and inflamed. When we +take these things into the stomach, they cause the stomach to smart, +and its lining membrane becomes red just as the skin or the eye does. + +~13.~ Nature has put into our foods very nice flavors to make us enjoy +eating them. Condiments are likely to do us great harm, and hence it is +far better not to use them. + +~14. Tobacco.~--Most of you know that tobacco is obtained from a plant +which has long, broad leaves. These leaves are dried and then rolled up +into cigars, ground into snuff, or prepared for chewing. + +[Illustration: Tobacco-Plant.] + +~15.~ Tobacco has a smarting, sickening taste. Do you think it would be +good to eat? Why not? + +~16.~ You know that tobacco makes people sick when they first begin to +use it. This is because it contains a very deadly poison, called +_nicotine_. + +~17.~ If you give tobacco to a cat or a dog, it will become very sick. A +boy once gave a piece of tobacco to a monkey, which swallowed it not +knowing what a bad thing it was. The monkey soon became sick and died. + +~18.~ Many learned doctors have noticed the effects which come from +using tobacco, and they all say it does great harm to boys, that it +makes them puny and weak, and prevents their growing up into strong and +useful men. If tobacco is not good for boys, do you think it can be good +for men? Certainly you will say, No. + + +SUMMARY. + +1. Both animals and plants are sometimes diseased. Flesh obtained from +sick or diseased animals is unfit for food. + +2. Unripe, stale, and mouldy foods are unfit to be eaten and likely to +cause severe illness. + +3. Foods are sometimes spoiled by having things mixed with them which +are not food, or which are poisonous. + +4. The foods most liable to be adulterated in this way are milk, sugar, +and butter. + +5. Tobacco, while not actually eaten, is thought by some persons to be a +food, but it is not. It is a poison, and injures all who use it. + +6. Boys who use tobacco do not grow strong in body and mind. + + + + +CHAPTER VI. + +OUR DRINKS. + + +~1.~ Water is really the only drink. It is the only substance which will +satisfy thirst. All other fluids which we drink consist mostly of water. +Thus, lemonade is lemon-juice and water. Milk is chiefly water. Wine, +beer, cider, and such liquids contain alcohol and many other things, +mixed with water. + +~2. Why we Need Water.~--If we should wet a sponge and lay it away, it +would become dry in a few hours, as the water would pass off into the +air. Our bodies are losing water all the time, and we need to drink to +keep ourselves from drying up. + +~3.~ Water is also very necessary for other purposes. It softens our +food so that we can chew and swallow it, and helps to carry it around in +the body after it has been digested, in a way about which we shall learn +in future lessons. + +~4.~ Still another use for water is to dissolve and wash out of our +bodies, through the sweat of the skin, and in other ways, the waste and +worn-out particles which are no longer of any use. + +~5. Impure Water.~--Most waters have more or less substances dissolved +in them. Water which has much lime in it is called hard water. Such +water is not so good to drink, or for use in cooking, as soft water. +That water is best which holds no substances in solution. Well-water +sometimes contains substances which soak into wells from vaults or +cesspools. Slops which are poured upon the ground soak down out of +sight; but the foul substances which they contain are not destroyed. +They remain in the soil, and when the rains come, they are washed down +into the well if it is near by. You can see some of the things found in +bad water in the illustration given on opposite page. + +~6.~ It is best not to drink iced water when the body is heated, or +during meals. If it is necessary to drink very cold water, the bad +effects may be avoided by sipping it very slowly. + +~7. Tea and Coffee.~--Many people drink tea or coffee at their meals, +and some persons think that these drinks are useful foods; but they +really have little or no value as foods. Both tea and coffee contain a +poison which, when separated in a pure form, is so deadly that a very +small quantity is enough to kill a cat or a dog. This poison often does +much harm to those who drink tea or coffee very strong for any great +length of time. + +[Illustration: A DROP OF IMPURE WATER MAGNIFIED.] + +~8. Alcohol~ (al'-co-hol).--All of you know something about alcohol. +Perhaps you have seen it burn in a lamp. It will burn without a lamp, if +we light it. It is so clear and colorless that it looks like water. The +Indians call it "fire-water." Alcohol differs very much from foods. It +is not produced from plants, as fruits and grains are; neither is it +supplied by Nature ready for our use, as are air and water. + +~9. Fermentation.~--When a baker makes bread he puts some yeast in the +dough to make it "rise," so the bread will be light. The yeast destroys +some of the sugar and starch in the flour and changes it into alcohol +and a gas. The gas bubbles up through the dough, and this is what makes +the bread light. This is called _fermentation_ (fer-men-ta'-tion). The +little alcohol which is formed in the bread does no harm, because it is +all driven off by the heat when the bread is baked. + +[Illustration: FERMENTATION.] + +~10.~ Any moist substance or liquid which contains sugar will ferment if +yeast is added to it, or if it is kept in a warm place. You know that +canned fruit sometimes spoils. This is because it ferments. Fermentation +is a sort of decay. When the juice of grapes, apples, or other fruit is +allowed to stand in a warm place it "works," or ferments, and thus +produces alcohol. Wine is fermented grape-juice; hard cider is fermented +apple-juice. + +~11.~ Beer, ale, and similar drinks are made from grains. The grain is +first moistened and allowed to sprout. In sprouting, the starch of the +grain is changed to sugar. The grain is next dried and ground, and is +then boiled with water. The water dissolves the sugar. The sweet liquid +thus obtained is separated from the grain, and yeast is added to it. +This causes it to ferment, which changes the sugar to alcohol. Thus we +see that the grain does not contain alcohol in the first place, but that +it is produced by fermentation. + +~12.~ All fermented liquids contain more or less alcohol, mixed with +water and a good many other things. Rum, brandy, gin, whiskey, and pure +alcohol are made by separating the alcohol from the other substances. +This is done by means of a still, and is called _distillation_. + +[Illustration: DISTILLATION.] + +~13.~ You can learn how a still separates the alcohol by a little +experiment. When a tea-pot is boiling on the stove and the steam is +coming out at the nozzle, hold up to the nozzle a common drinking-glass +filled with iced water, first taking care to wipe the outside of the +glass perfectly dry. Little drops of water will soon gather upon the +side of the glass. If you touch these to the tongue you will observe +that they taste of the tea. It is because a little of the tea has +escaped with the steam and condensed upon the glass. This is +distillation. + +~14.~ If the tea-pot had contained wine, or beer, or hard cider, the +distilled water would have contained alcohol instead of tea. By +distilling the liquid several times the alcohol may be obtained almost +pure. + +~15. Alcohol kills Animals and Plants.~--Strong alcohol has a deadly +effect upon all living things. Once a man gave a dog a few +tablespoonfuls of alcohol, and in a little while the dog was dead. If +you should pour alcohol upon a plant it would die very soon. + +~16.~ A man once made a cruel experiment. He put some minnows into a jar +of water and then poured in a few teaspoonfuls of alcohol. The minnows +tried very hard to get out, but they could not, and in a little while +they were all dead, poisoned by the alcohol. A Frenchman once gave +alcohol to some pigs with their food. They soon became sick and died. + +~17. Alcohol not a Food.~--There are some people who imagine that +alcohol is good for food because it is made from fruits and grains which +are good for food. This is a serious mistake. A person can live on the +fruits or grains from which alcohol is made, but no one would attempt +to live upon alcohol. If he did, he would soon starve to death. In fact, +men have often died in consequence of trying to use whiskey in place of +food. + +~18.~ We should remember, also, that people do not take alcohol as a +food, but for certain effects which it produces, which are not those of +a food, but of a poison. + +~19.~ Many people who would not drink strong or distilled liquors, think +that they will suffer no harm if they use only wine, beer, or cider. +This is a great mistake. These liquids contain alcohol, as do all +fermented drinks. A person will become drunk or intoxicated by drinking +wine, beer, or cider--only a larger quantity is required to produce the +same effect as rum or whiskey. + +~20.~ Another very serious thing to be thought of is that if a person +forms the habit of drinking wine, cider, or other fermented drinks, he +becomes so fond of the _effect they produce_ that he soon wants some +stronger drink, and thus he is led to use whiskey or other strong +liquors. On this account it is not safe to use any kind of alcoholic +drinks, either fermented or distilled. The only safe plan is to avoid +the use of every sort of stimulating or intoxicating drinks. + +~21.~ It has been found by observation that those persons who use +intoxicating drinks are not so healthy as those who do not use them, +and, as a rule, they do not live so long. + +~22.~ This is found to be true not only of those who use whiskey and +other strong liquors, but also of those who use fermented drinks, as +wine and beer. Beer drinkers are much more likely to suffer from disease +than those who are strictly temperate. It is often noticed by physicians +that when a beer-drinker becomes sick or meets with an accident, he does +not recover so readily as one who uses no kind of alcoholic drinks. + +~23.~ Alcoholic drinks not only make people unhealthy and shorten their +lives, but they are also the cause of much poverty and crime and an +untold amount of misery. + + +SUMMARY. + +1. Water is the only thing that will satisfy thirst. + +2. In going through our bodies, water washes out many impurities. We +also need water to soften our food. + +3. The purest water is the best. Impure water causes sickness. + +4. Good water has no color, taste, or odor. + +5. Tea and coffee are not good drinks. They are very injurious to +children, and often do older persons much harm. + +6. Alcohol is made by fermentation. + +7. Pure alcohol and strong liquors are made by distillation. + +8. Alcohol is not a food, it is a poison. It kills plants and animals, +and is very injurious to human beings. + +9. Even the moderate use of alcoholic drinks produces disease and +shortens life. + + + + +CHAPTER VII. + +HOW WE DIGEST. + + +~1.~ Did you ever see a Venus's fly-trap? This curious plant grows in +North Carolina. It is called a fly-trap because it has on each of its +leaves something like a steel-trap, by means of which it catches flies. +You can see one of these traps in the picture. When a fly touches the +leaf, the trap shuts up at once, and the poor fly is caught and cannot +get away. The harder it tries to escape, the more tightly the trap +closes upon it, until after a time it is crushed to death. + +[Illustration: VENUS'S FLY-TRAP.] + +~2.~ But we have yet to learn the most curious thing about this strange +plant, which seems to act so much like an animal. If we open the leaf +after a few days, it will be found that the fly has almost entirely +disappeared. The fly has not escaped, but it has been dissolved by a +fluid formed inside of the trap, and the plant has absorbed a portion of +the fly. In fact, it has really eaten it. The process by which food is +dissolved and changed so that it can be absorbed and may nourish the +body, is called _digestion_ (di-ges'-tion). + +~3.~ The Venus's fly-trap has a very simple way of digesting its food. +Its remarkable little trap serves it as a mouth to catch and hold its +food, and as a stomach to digest it. The arrangement by which our food +is digested is much less simple than this. Let us study the different +parts by which this wonderful work is done. + +[Illustration: THE DIGESTIVE TUBE.] + +~4. The Digestive Tube.~--The most important part of the work of +digesting our food is done in a long tube within the body, called the +_digestive tube_ or _canal_. + +~5.~ This tube is twenty-five or thirty feet long in a full-grown man; +but it is so coiled up and folded away that it occupies but little +space. It begins at the mouth, and ends at the lower part of the trunk. +The greater part of it is coiled up in the abdomen. + +~6. The Mouth.~--The space between the upper and the lower jaw is called +the _mouth_. The lips form the front part and the cheeks the sides. At +the back part are three openings. One, the upper, leads into the nose. +There are two lower openings. One of these leads into the stomach, and +the other leads to the lungs. The back part of the mouth joins the two +tubes which lead from the mouth to the lungs and the stomach, and is +called the _throat_. The mouth contains the _tongue_ and the _teeth_. + +[Illustration: THE TEETH.] + +~7. The Teeth.~--The first teeth, those which come when we are small +children, are called _temporary_ or _milk teeth_. We lose these teeth +as the jaws get larger and the second or _permanent_ teeth take their +place. There are twenty teeth in the first set, and thirty-two in the +second. Very old persons sometimes have a third set of teeth. + +[Illustration: SALIVARY GLANDS.] + +~8. The Salivary~ (sal'-i-vary)~ Glands.~--There are three pairs of +_salivary glands_. They form a fluid called the _saliva_ (sa-li'-va). It +is this fluid which moistens the mouth at all times. When we eat or +taste something which we like, the salivary glands make so much saliva +that we sometimes say the mouth waters. One pair of the salivary glands +is at the back part of the lower jaw, in front of the ears. The other +two pairs of glands are placed at the under side of the mouth. The +saliva produced by the salivary glands is sent into the mouth through +little tubes called _ducts_. + +~9. The Gullet.~--At the back part of the throat begins a narrow tube, +which passes down to the stomach. This tube is about nine inches long. +It is called the _gullet_, _food-pipe_, or _oesophagus_ +(e-soph'-a-gus). + +~10. The Stomach.~--At the lower end of the oesophagus the digestive +tube becomes enlarged, and has a shape somewhat like a pear. This is the +_stomach_. In a full-grown person the stomach is sufficiently large to +hold about three pints. At each end of the stomach is a narrow opening +so arranged that it can be opened or tightly closed, as may be +necessary. The upper opening allows the food to pass into the stomach, +the lower one allows it to pass out into the intestines. This opening is +called the _pylorus_ (py-lo'-rus), or gate-keeper, because it closes so +as to keep the food in the stomach until it is ready to pass out. + +~11.~ In the membrane which lines the stomach there are many little +pocket-like glands, in which a fluid called the _gastric juice_ is +formed. This fluid is one of the most important of all the fluids formed +in the digestive canal. + +[Illustration: GASTRIC GLAND.] + +~12. The Intestine~(in-tes'-tine).--At the lower end of the stomach +the digestive canal becomes narrow again. This narrow portion, called +the _intestine_, is about twenty-five feet long in a grown person. The +last few feet of the intestine is larger than the rest, and is called +the _colon_. This long tube is coiled up and snugly packed away in the +cavity of the abdomen. In the membrane lining the intestines are to be +found little glands, which make a fluid called _intestinal juice_. + +~13. The Liver.~--Close up under the ribs, on the right side of the +body, is a large chocolate-colored organ, called the _liver_. The liver +is about half as large as the head, and is shaped so as to fit snugly +into its corner of the abdomen. The chief business of the liver is to +make a fluid called _bile_, which is very necessary for the digestion of +our food. + +~14.~ The bile is a bitter fluid of a golden-brown color. It is carried +to the intestine by means of a little tube or duct, which enters the +small intestine a few inches below the stomach. When the bile is made +faster than it is needed for immediate use, it is stored up in a little +pear-shaped sac called the _gall-bladder_, which hangs from the under +side of the liver. + +~15.~ The liver is a very wonderful organ, and does many useful things +besides making bile. It aids in various ways in digesting the food, and +helps to keep the blood pure by removing from it harmful substances +which are formed within the body. + +~16. The Pancreas~(pan'-cre-as).--The _pancreas_ is another large and +very important gland which is found close to the stomach, lying just +behind it in the abdominal cavity. The pancreas forms a fluid called the +_pancreatic juice_, which enters the small intestine at nearly the same +place as the bile. + +~17. The Spleen.~--Close to the pancreas, at the left side of the body, +is a dark, roundish organ about the size of the fist, called the +_spleen_. It is not known that the spleen has much to do in the work of +digestion, but it is so closely connected with the digestive organs that +we need to know about it. + +~18.~ Please note that there are five important organs of digestion. The +mouth, the stomach, the intestines, the pancreas, and the liver. + +~19.~ Also observe that there are five digestive fluids, saliva, +gastric juice, bile, pancreatic juice, and intestinal juice. + + +SUMMARY. + +1. The process of dissolving and changing the food so that it may be +absorbed and may nourish the body is digestion. + +2. The work of digestion is chiefly done in the digestive tube or canal, +which is about thirty feet in length. + +3. The mouth contains the teeth, and has three pairs of salivary glands +connected with it, which make saliva. + +4. The gullet leads from the mouth to the stomach. + +5. The stomach is pear-shaped, and holds about three pints. + +6. It has an upper and a lower opening, each of which is guarded by a +muscle, which keeps its contents from escaping. + +7. The lower opening of the stomach is called the pylorus. + +8. The stomach forms the gastric juice. + +9. The intestines are about twenty-five feet long. They form the +intestinal juice. + +10. The liver lies under the ribs of the right side. It is about half as +large as the head. It makes bile. + +11. When not needed for immediate use, the bile is stored up in a sac +called the gall-bladder. + +12. The pancreas is a gland which lies just back of the stomach. It +makes pancreatic juice. + +13. The spleen is found near the pancreas. + +14. There are five important digestive organs--the mouth, the stomach, +the intestines, the liver, and the pancreas. + +15. There are five digestive fluids--saliva, gastric juice, intestinal +juice, bile, and pancreatic juice. + + + + +CHAPTER VIII. + +DIGESTION OF A MOUTHFUL OF BREAD. + + +~1.~ Let us suppose that we have eaten a mouthful of bread, and can +watch it as it goes through all the different processes of digestion. + +~2. Mastication.~--First, we chew or masticate the food with the teeth. +We use the tongue to move the food from one side of the mouth to the +other, and to keep the food between the teeth. + +~3. Mouth Digestion.~--While the bread is being chewed, the saliva is +mixed with it and acts upon it. The saliva moistens and softens the food +so that it can be easily swallowed and readily acted upon by the other +digestive juices. You have noticed that if you chew a bit of hard bread +a few minutes it becomes sweet. This is because the saliva changes some +of the starch of the food into sugar. + +~4.~ After we have chewed the food, we swallow it, and it passes down +through the oesophagus into the stomach. + +~5. Stomach Digestion.~--As soon as the morsel of food enters the +stomach, the gastric juice begins to flow out of the little glands in +which it is formed. This mingles with the food and digests another +portion which the saliva has not acted upon. While this is being done, +the stomach keeps working the food much as a baker kneads dough. This is +done to mix the gastric juice with the food. + +~6.~ After an hour or two the stomach squeezes the food so hard that a +little of it, which has been digested by the gastric juice and the +saliva, escapes through the lower opening, the pylorus, of which we have +already learned. As the action of the stomach continues, more of the +digested food escapes, until all that has been properly acted upon has +passed out. + +~7. Intestinal Digestion.~--We sometimes eat butter with bread, or take +some other form of fat in our food. This is not acted upon by the saliva +or the gastric juice. When food passes out of the stomach into the small +intestine, a large quantity of bile is at once poured upon it. This bile +has been made beforehand by the liver and stored up in the gall-bladder. +The bile helps to digest fats, which the saliva and the gastric juice +cannot digest. + +~8.~ The pancreatic juice does the same kind of work that is done by the +saliva, the gastric juice, and the bile. It also finishes up the work +done by these fluids. It is one of the most important of all the +digestive juices. + +~9.~ The intestinal juice digests nearly all the different elements of +the food, so that it is well fitted to complete the wonderful process by +which the food is made ready to enter the blood and to nourish the body. + +~10.~ While the food is being acted upon by the bile, the pancreatic +juice, and intestinal juice, it is gradually moved along the intestines. +After all those portions of food which can be digested have been +softened and dissolved, they are ready to be taken into the blood and +distributed through the body. + +~11. Absorption.~--If you put a dry sponge into water, it very soon +becomes wet by soaking up the water. Indeed, if you only touch a corner +of the sponge to the water, the whole sponge will soon become wet. We +say that the sponge absorbs the water. It is in a somewhat similar way +that the food is taken up or absorbed by the walls of the stomach and +intestines. When the food is absorbed, the greater part of it is taken +into the blood-vessels, of which we shall learn in a future lesson. + +~12. Liver Digestion.~--After the food has been absorbed, the most of it +is carried to the liver, where the process of digestion is completed. +The liver also acts like an inspector to examine the digested food and +remove hurtful substances which may be taken with it, such as alcohol, +mustard, pepper, and other irritating things. + +~13. The Thoracic Duct.~--A portion of the food, especially the digested +fats, is absorbed by a portion of the lymphatic vessels called +_lacteals_, which empty into a small vessel called the _thoracic duct_. +This duct passes upward in front of the spine and empties into a vein +near the heart. + + +SUMMARY. + +How a mouthful of food is digested: + +1. It is first masticated--that is, it is chewed and moistened with +saliva. + +2. Then it is swallowed, passing through the oesophagus to the +stomach. + +3. There it is acted upon, and a part of it digested by the gastric +juice. + +4. It is then passed into the small intestine, where it is acted upon by +the bile, the pancreatic fluid, and the intestinal juice. + +5. The digested food is then absorbed by the walls of the stomach and +intestines. + +6. The greater portion of the food is next passed through the liver, +where hurtful substances are removed. + +7. A smaller portion is carried through the thoracic duct and emptied +into a vein near the heart. + + + + +CHAPTER IX. + +BAD HABITS IN EATING. + + +~1. Eating too Fast.~--A most common fault is eating too fast. When the +food is chewed too rapidly, and swallowed too quickly, it is not +properly divided and softened. Such food cannot be easily acted upon by +the various digestive juices. + +~2. Eating too Much.~--A person who eats food too rapidly is also very +likely to injure himself by eating too much. The digestive organs are +able to do well only a certain amount of work. When too much food is +eaten, none of it is digested as well as it should be. Food which is not +well digested will not nourish the body. + +~3. Eating too Often~--Many children make themselves sick by eating too +often. It is very harmful to take lunches or to eat at other than the +proper meal-times. The stomach needs time to rest, just as our legs and +arms and the other parts of the body do. For the same reason, it is well +for us to avoid eating late at night. The stomach needs to sleep with +the rest of the body. If one goes to bed with the stomach full of food, +the stomach cannot rest, and the work of digestion will go on so slowly +that the sleep will likely be disturbed. Such sleep is not refreshing. + +~4.~ If we wish to keep our digestive organs in good order, we must take +care to eat at regular hours. We ought not to eat when we are very +tired. The stomach cannot digest well when we are very much fatigued. + +~5. Sweet Foods.~--We ought not to eat too much sugar or sweet foods, as +they are likely to sour or ferment in the stomach, and so make us sick. +Candies often contain a great many things which are not good for us, and +which may make us sick. The colors used in candies are sometimes +poisonous. The flavors used in them are also sometimes very harmful. + +~6. Fatty Foods Hurtful.~--Too much butter, fat meats, and other greasy +foods are hurtful. Cream is the most digestible form of fat, because it +readily dissolves in the fluids of the stomach, and mixes with the other +foods without preventing their digestion. Melted fats are especially +harmful. Cheese, fried foods, and rich pastry are very poor foods, and +likely to cause sickness. + +~7. Eating too many Kinds of Foods.~--Children should avoid eating +freely of flesh meats. They ought also to avoid eating all +highly-seasoned dishes, and taking too many kinds of food at a meal. A +simple diet is much the more healthful. Milk and grain foods, as +oatmeal, cracked wheat, graham bread, with such delicious fruits as +apples, pears, and grapes, are much the best food for children. + +~8. Avoid Use of Cold Foods.~--We ought not to take very cold foods or +liquids with our meals. Cold foods, ice-water, and other iced drinks +make the stomach so cold that it cannot digest the food. For this reason +it is very harmful to drink iced water or iced tea, or to eat ice-cream +at meals. These things are injurious to us at any time, but they do the +greatest amount of harm when taken with the food. + +~9. Things sometimes Eaten which are not Foods.~--Things which are not +foods are often used as foods, such as mustard, pepper, and the various +kinds of seasonings. Soda, saleratus, and baking-powders also belong to +this class. All of these substances are more or less harmful, +particularly mustard, pepper, and hot sauces. + +~10. Common Salt.~--The only apparent exception to the general rule that +all condiments and other substances which are not foods are harmful is +in the case of common salt. This is very commonly used among civilized +nations, although there are many barbarous tribes that never taste it. +It is quite certain that much more salt is used than is needed. When +much salt is added to the food, the action of the digestive fluids is +greatly hindered. Salt meats, and other foods which have much salt added +to them, are hard to digest because the salt hardens the fibres of the +meat, so that they are not easily dissolved by the digestive fluids. + +~11. Care of the Teeth.~--The teeth are the first organs employed in the +work of digestion. It is of great importance that they should be kept in +health. Many persons neglect their teeth, and treat them so badly that +they begin to decay at a very early age. + +~12.~ The mouth and teeth should be carefully cleansed immediately on +rising in the morning, and after each meal. All particles of food should +be removed from between the teeth by carefully rubbing both the inner +and the outer surfaces of the teeth with a soft brush, and rinsing very +thoroughly with water. A little soap may be used in cleansing the teeth, +but clear water is sufficient, if used frequently and thoroughly. The +teeth should not be used in breaking nuts or other hard substances. The +teeth are brittle, and are often broken in this way. The use of candy +and too much sweet food is also likely to injure the teeth. + +~13.~ Some people think that it is not necessary to take care of the +first set of teeth. This is a great mistake. If the first set are lost +or are unhealthy, the second set will not be as perfect as they should +be. It is plain that we should not neglect our teeth at any time of +life. + +~14. Tobacco.~--When a person first uses tobacco, it is apt to make him +very sick at the stomach. After he has used tobacco a few times it does +not make him sick, but it continues to do his stomach and other organs +harm, and after a time may injure him very seriously. Smokers sometimes +suffer from a horrible disease of the mouth or throat known as cancer. + +~15. Effects of Alcohol upon the Stomach.~--If you should put a little +alcohol into your eye, the eye would become very red. When men take +strong liquors into their stomachs, the delicate membrane lining the +stomach becomes red in the same way. Perhaps you will ask how do we know +that alcohol has such an effect upon the stomach. More than sixty years +ago there lived in Michigan a man named Alexis St. Martin. One day he +was, by accident, shot in such a way that a large opening was made right +through the skin and flesh and into the stomach. The good doctor who +attended him took such excellent care of him that he got well. But when +he recovered, the hole in his stomach remained, so that the doctor could +look in and see just what was going on. St. Martin sometimes drank +whiskey, and when he did, the doctor often looked into his stomach to +see what the effect was, and he noticed that the inside of the stomach +looked very red and inflamed. + +~16.~ If St. Martin continued to drink whiskey for several days, the +lining of the stomach looked very red and raw like a sore eye. A sore +stomach cannot digest food well, and so the whole body becomes sick and +weak. What would you think of a man who should keep his eyes always sore +and inflamed and finally destroy his eyesight by putting pepper or +alcohol or some other irritating substance into them every day? Is it +not equally foolish and wicked to injure the stomach and destroy one's +digestion by the use of alcoholic drinks? Alcohol, even when it is not +very strong, not only hurts the lining of the stomach, but injures the +gastric juice, so that it cannot digest the food well. + +~17. Effects of Alcohol upon the Liver.~--The liver, as well as the +stomach, is greatly damaged by the use of alcohol. You will recollect +that nearly all the food digested and absorbed is filtered through the +liver before it goes to the heart to be distributed to the rest of the +body. In trying to save the rest of the body from the bad effects of +alcohol, the liver is badly burned by the fiery liquid, and sometimes +becomes so shrivelled up that it can no longer produce bile and perform +its other duties. Even beer, ale, and wine, which do not contain so much +alcohol as do rum, gin, and whiskey, have enough of the poison in them +to do the liver a great deal of harm, and to injure many other organs of +the body as well. + + +SUMMARY. + + {Eating too fast. + {Eating too much. + {Eating too frequently. + {Eating irregularly. + 1. CAUSES OF INDIGESTION. {Eating when tired. + {Eating too much of sweet foods. + {Eating too many kinds of food + at a meal. + {Using iced foods or drinks. + +2. Irritating substances and things which are not foods should not be +eaten. + +3. The teeth must be carefully used and kept clean. + +4. Tobacco-using does the stomach harm, and sometimes causes cancer of +the mouth. + +5. Alcohol injures the gastric juice, and causes disease of the stomach +and the liver. + + + + +CHAPTER X. + +A DROP OF BLOOD. + + +~1. The Blood.~--Did you ever cut or prick your finger so as to make it +bleed? Probably you have more than once met with an accident of this +sort. All parts of the body contain blood. If the skin is broken in any +place the blood flows out. + +~2.~ How many of you know what a microscope is? It is an instrument +which magnifies objects, or makes them look a great deal larger than +they really are. Some microscopes are so powerful that they will make a +little speck of dust look as large as a great rock. + +~3. The Blood Corpuscles.~--If you should look at a tiny drop of blood +through such a microscope, you would find it to be full of very small, +round objects called _blood corpuscles_. + +~4.~ You would notice also that these corpuscles are of two kinds. Most +of them are slightly reddish, and give to the blood its red color. A +very few are white. + +~5. Use of the Corpuscles.~--Do you wonder what these peculiar little +corpuscles do in the body? They are very necessary. We could not live a +moment without them. We need to take into our bodies oxygen from the +air. It is the business of the red corpuscles to take up the oxygen in +the lungs and carry it round through the body in a wonderful way, of +which we shall learn more in a future lesson. + +~6.~ The white corpuscles have something to do with keeping the body in +good repair. They are carried by the blood into all parts of the body +and stop where they are needed to do any kind of work. They may be +compared to the men who go around to mend old umbrellas, and to do other +kinds of tinkering. It is thought that the white corpuscles turn into +red ones when they become old. + +~7.~ The corpuscles float in a clear, almost colorless fluid which +contains the digested food and other elements by which the body is +nourished. + + +SUMMARY. + +1. The blood contains very small objects called blood corpuscles. + +2. There are two kinds of corpuscles, red and white. + +3. The red corpuscles carry oxygen. + +4. The white corpuscles repair parts that are worn. + +5. The corpuscles float in a clear, almost colorless fluid, which +nourishes the body. + + + + +CHAPTER XI. + +WHY THE HEART BEATS. + + +~1.~ If you place your hand on the left side of your chest, you will +feel something beating. If you cannot feel the beats easily, you may run +up and down stairs two or three times, and then you can feel them very +distinctly. How many of you know the name of this curious machine inside +the chest, that beats so steadily? You say at once that it is the heart. + +[Illustration: THE HEART.] + +~2.~ The Heart.--The heart may be called a live pump, which keeps +pumping away during our whole lives. If it should stop, even for a +minute or two, we would die. If you will place your hand over your heart +and count the beats for exactly one minute, you will find that it beats +about seventy-five or eighty times. When you are older, your heart will +beat a little more slowly. If you count the beats while you are lying +down, you will find that the heart beats more slowly than when you are +sitting or standing. When we run or jump, the heart beats much harder +and faster. + +~3. Why the Heart Beats.~--We have learned in preceding lessons that the +digested food is taken into the blood. We have also learned that both +water and oxygen are taken into the blood. Thus the blood contains all +the materials that are needed by the various parts of the body to make +good the wastes that are constantly taking place. But if the blood were +all in one place it could do little good, as the new materials are +needed in every part of the body. There has been provided a wonderful +system of tubes running through every part of the body. By means of +these tubes the blood is carried into every part where it is required. +These tubes are connected with the heart. When the heart beats, it +forces the blood through the tubes just as water is forced through a +pipe by a pump or by a fire-engine. + +~4. The Heart Chambers.~--The heart has four chambers, two upper and +two lower chambers. The blood is received into the upper chambers, and +is then passed down into the lower chambers. From the lower chambers it +is sent out to various parts of the body. + +[Illustration: THE INSIDE OF THE HEART.] + +~5. The Blood-Vessels.~--The tubes through which the blood is carried +are called _blood-vessels_. There are three kinds of blood-vessels. One +set carry the blood away from the heart, and are called _arteries_ +(ar'-te-ries). Another set return the blood to the heart, and are called +_veins_. The arteries and veins are connected at the ends farthest from +the heart by many very small vessels. These minute, hairlike vessels are +called _capillaries_ (cap'-il-la-ries). + +~6. The Arteries.~--An artery leads out from the lower chamber of each +side of the heart. The one from the right side of the heart carries the +blood only to the lungs. The one from the left side of the heart carries +blood to every part of the body. It is the largest artery in the body, +and is called the _aorta_. Soon after it leaves the heart the aorta +begins to send out branches to various organs. These divide in the +tissues again and again until they become so small that only one +corpuscle can pass through at a time, as shown in the colored plate. +(Frontispiece.) + +~7. The Veins.~--These very small vessels now begin to unite and form +larger ones, the veins. The small veins join to form larger ones, until +finally all are gathered into two large veins which empty into the upper +chamber of the right side of the heart. The veins which carry blood from +the lungs to the heart empty into the upper chamber of the left side of +the heart. + +~8. What is Done in the Blood-Vessels.~--While the blood is passing +through the small blood-vessels in the various parts of the body, each +part takes out just what it needs to build up its own tissues. At the +same time, the tissues give in exchange their worn-out or waste matters. +The red blood corpuscles in the capillaries give up their oxygen, and +the blood receives in its stead a poisonous substance called +carbonic-acid gas. + +~9. Red and Blue Blood.~--While in the arteries the blood is of a bright +red color; but while it is passing through the capillaries the color +changes to a bluish red or purple color. The red blood is called +_arterial blood_, because it is found in the arteries. The purple blood +is called _venous blood_, because it is found in the veins. The loss of +oxygen in the corpuscles causes the change of color. + +~10. Change of Blood in the Lungs.~--Exactly the opposite change occurs +in the blood when it passes through the lungs. The blood which has been +gathered up from the various parts of the body is dark, impure blood. In +the lungs this dark blood is spread out in very minute capillaries and +exposed to the air. While passing through the capillaries of the lungs, +the blood gives up some of its impurities in exchange for oxygen from +the air. The red corpuscles absorb the oxygen and the color of the blood +changes from dark purple to bright red again. The purified blood is then +carried back to the upper chamber of the left side of the heart through +four large veins. The blood is now ready to begin another journey around +the body. + +~11. The Pulse.~--If you place your finger on your wrist at just the +right spot, you can feel a slight beating. This beating is called the +_pulse_. It is caused by the movement of the blood in the artery of the +wrist at each beat of the heart. The pulse can be felt at the neck and +in other parts of the body where an artery comes near to the surface. + +~12. How much Work the Heart Does.~--The heart is a small organ, only +about as large as your fist, and yet it does an amount of work which is +almost beyond belief. Each time it beats, it does as much work as your +arm would do in lifting a large apple from the ground to your mouth. It +beats when we are asleep as well as when we are awake. When we run we +know by the way in which it beats that it is working very fast. Do you +know how much a ton is? Well, in twenty-four hours the heart does as +much work as a man would do in lifting stones enough to weigh more than +one hundred and twenty tons. + +~13. The Lymphatics.~--While the blood is passing through the +capillaries, some of the white corpuscles escape from the blood-vessels. +What do you suppose becomes of these runaway corpuscles? Nature has +provided a way by which they can get back to the heart. In the little +spaces among the tissues outside of the blood-vessels very minute +channels called _lymph channels_ or _lymphatics_ (lym--phat'-ics) begin. +The whole body is filled with these small channels, which run together +much like the meshes of a net. In the centre of the body the small +lymphatics run into large ones, which empty into the veins near the +heart. This is the way the stray white blood corpuscles get back into +the blood. + +~14. The Lymph.~--In the lymph channels the white corpuscles float in a +colorless fluid called _lymph_. The lymph is composed of the fluid +portion of the blood which has soaked through the walls of the small +vessels. The chief purpose of the lymphatics is to carry the lymph from +the tissues back to the heart. + +~15. Lymphatic Glands.~--Here and there, scattered through the body, are +oval structures into each of which many lymphatic vessels are found to +run, as shown in the illustration. These are called _lymphatic glands_. + +[Illustration: LYMPH GLAND AND VESSELS.] + +~16.~ The heart and blood-vessels are among the most wonderful +structures in the body. It is no wonder, then, that alcohol, tobacco, +and other narcotics and stimulants produce their most deadly effects +upon these delicate organs. What these effects are we shall learn more +fully in the next chapter. + + +SUMMARY. + +1. The heart beats to circulate the blood. + +2. The heart has four chambers, two upper and two lower. + +3. There are tubes called blood-vessels which carry the blood to all +parts of the body. + +4. These tubes are connected with the heart. + +5. The vessels which carry blood away from the heart are called +arteries, and those which carry blood back to the heart are called +veins. + +6. The arteries and veins are connected by small tubes called +capillaries. + +7. The blood found in the arteries is red; that in the veins is dark +blue or purple. + +8. The color of the blood changes from red to blue in going through the +capillaries. The change is due to the loss of oxygen. + +9. In the circulation of the lungs, the blood in the arteries is blue, +that in the veins, red. + +10. The change from blue to red takes place while the blood is passing +through the capillaries of the lungs. The change is due to the oxygen +which the corpuscles of the blood take up in the lungs. + +11. The pulse is caused by the beating of the heart. + +12. The heart does a great deal of work every day in forcing the blood +into different parts of the body. + +13. Some of the white blood corpuscles escape from the blood-vessels +through the thin walls of the capillaries. + +14. These corpuscles return to the heart through small vessels called +lymph channels or lymphatics. + +15. The lymphatics in many parts of the body run into small roundish +bodies called lymphatic glands. + +16. The object of the lymphatics is to remove from the tissues and +return to the general circulation the lymph and white blood corpuscles +which escape through the walls of the capillaries. + + + + +CHAPTER XII. + +HOW TO KEEP THE HEART AND THE BLOOD HEALTHY. + + +~1.~ The heart is one of the most important of all the organs of the +body. If we take good care of it, it will do good service for us during +a long life. Let us notice some ways in which the heart is likely to be +injured. + +~2. Violent Exercise.~--Did you ever run so hard that you were out of +breath? Do you know why you had to breathe so fast? It was because the +violent exercise made your heart beat so rapidly that the blood could +not get out of the lungs as fast as the heart forced it in. The lungs +became so filled with blood that they could not do their work well. +Sometimes, when a person runs very fast or takes any kind of violent +exercise, the lungs become so filled with blood that a blood-vessel is +broken. The person may then bleed to death. It is very unwise to overtax +the heart in any way, for it may be strained or otherwise injured, so +that it can never again do its work properly. + +~3. Effects of Bad Air.~--Bad air is very harmful to the heart and to +the blood also. We should always remember that the blood of the body +while passing through the lungs is exposed to the air which we breathe. +If the air is impure, the blood will be poisoned. In churches and in +other places where the air becomes foul, people often faint from the +effects of the impure air upon the heart. It is important that the air +of the rooms in which we live and sleep should be kept very pure by good +ventilation. + +~4. Effects of Bad Food.~--The blood is made from what we eat, and if we +eat impure and unwholesome food, the blood becomes impure. We ought to +avoid the use of rich or highly-seasoned foods, candies, and all foods +which are not nutritious. They not only injure the blood by making it +impure, but they cause poor digestion. + +~5. Plenty of Sleep Necessary.~--If we should take a drop of blood from +the finger of a person who had not had as much sleep as he needed, and +examine it with a microscope, we should find that there were too few of +the little red-blood corpuscles. This is one reason why a person who has +not had sufficient sleep looks pale. + +~6. Proper Clothing.~--We should be properly clothed, according to the +weather. In cold weather we need very warm clothing. In warm weather we +should wear lighter clothing. Our clothing should be so arranged that it +will keep all parts of the body equally warm, and thus allow the blood +to circulate properly. The feet are apt to be cold, being so far away +from the heart, and we should take extra pains to keep them warm and +dry. + +~7. Effects of Excessive Heat.~--In very hot weather, many persons are +injured by exposing themselves to the sun too long at a time. Persons +who drink intoxicating liquors are very often injured in this way, and +sometimes die of sunstroke. + +~8. Effects of Anger.~--When a person gets very angry, the heart +sometimes almost stops beating. Indeed, persons have died instantly in a +fit of passion. So you see it is dangerous for a person to allow himself +to become very angry. + +~9. Effects of Alcohol upon the Blood.~--If you should take a drop of +blood upon your finger, and put it under the microscope, and then add a +little alcohol to it, you would see that the corpuscles would be quickly +destroyed. In a few seconds they would be so shrivelled up that no one +could tell that they had ever been the beautiful little corpuscles which +are so necessary to health. When alcohol is taken as a drink, it does +not destroy the corpuscles so quickly, but it injures them so that they +are not able to do their work of absorbing and carrying oxygen well. +This is one reason why the faces of men who use alcoholic drinks often +look so blue. + +~10. Alcohol Overworks the Heart.~--Dr. Parkes, a very learned English +physician, took the pains to observe carefully the effects of alcohol +upon the heart of a soldier who was addicted to the use of liquor. He +counted the beats of the soldier's pulse when he was sober; and then +counted them again when he was using alcohol, and found that when the +soldier took a pint of gin a day his heart was obliged to do one fourth +more work than it ought to do. + +~11. Effects of Alcohol upon the Blood-Vessels.~--If you put your hands +into warm water, they soon become red. This is because the blood-vessels +of the skin become enlarged by the heat, so that they hold more blood. +Alcohol causes the blood to come to the surface in the same way. It is +this that causes the flushed cheeks and the red eyes of the drunkard. +Sometimes, after a man has been using alcohol a long time, the +blood-vessels of his face remain enlarged all the time. This makes his +nose grow too fast, and so in time it gets too large, and then he has a +rum-blossom. + +~12. Effects of Tobacco on the Heart and the Blood.~--When a boy first +tries to use tobacco, it makes him feel very sick. If you should feel +his pulse just then, you would find it very weak. This means that the +heart is almost paralyzed by the powerful poison of the tobacco. Tobacco +also injures the blood corpuscles. + +~13.~ _Tea_ and _coffee_ also do their share of mischief to the heart. +Those who use them very strong often complain of palpitation, or heavy +and irregular beating of the heart. + +~14. Taking Cold.~--People usually "catch cold" by allowing the +circulation to become disturbed in some way, as by getting the feet wet, +being chilled from not wearing sufficient clothing, sitting in a +draught, and in other similar ways. It is very important for you to know +that a cold is a serious thing, and should be carefully avoided. + +~15. Hemorrhage~ (hem'-or-rhage) ~or Loss of Blood.~--A severe loss of +blood is likely to occur as the result of accidents or injuries of +various sorts, and it is important to know what to do at once, as there +may not be time to send for a doctor before it will be too late to save +the injured person's life. Here are a few things to be remembered in all +such cases: + +~16.~ If the blood from a cut or other wound flows in spurts, and is of +a bright red color, it is from an artery. If it is dark-colored, and +flows in a steady stream, it is from a vein. + +~17. How to Stop the Bleeding of Wounds.~--If the bleeding vessel is an +artery, apply pressure on the side of the wound next to the heart. If +the bleeding is from a vein, apply it on the opposite side. It is +generally best to apply pressure directly over the wound or on both +sides. The pressure can be made with the thumbs or with the whole hand. +Grasp the part firmly and press very hard, or tie a handkerchief or +towel around the wounded part and twist it very tight. If an arm or limb +is the part injured, the person should be made to lie down, and the +injured part should be held up. This is of itself an excellent means of +stopping hemorrhage. + +~18. Nose-Bleed.~--For nose-bleed a very good remedy is holding one or +both hands above the head. The head should be held up instead of being +bent forward, and the corner of a dry handkerchief should be pressed +into the bleeding nostril. It is well to bathe the face with very hot +water, and to snuff hot water into the nostril if the bleeding is very +severe. If the bleeding is very bad or is not readily stopped, a +physician should be called. + + +SUMMARY. + +1. Violent exercise is likely to injure the heart. + +2. Bad air makes the blood impure and disturbs the action of the heart. + +3. Unwholesome food produces bad blood. + +4. Too little sleep makes the blood poor. + +5. Proper clothing is necessary to make the blood circulate equally in +different parts of the body. + +6. Violent anger may cause death by stopping the beating of the heart. + +7. Alcohol injures the blood. + +8. Alcohol overworks the heart. + +9. Alcohol enlarges the blood-vessels. + +10. Tobacco injures the blood. + +11. Tobacco weakens the heart and makes the pulse irregular. + +12. The use of strong tea and coffee causes palpitation of the heart. + +13. A cold is caused by a disturbance of the circulation. A cold should +never be neglected. + +14. When an artery is wounded, the blood is bright red and flows in +spurts. + +15. When a vein is wounded, the blood is purple and flows in a steady + stream. + +16. To stop bleeding from an artery, press on the side of the wound +towards the heart, or on both sides of the wound. + +17. When a vein is wounded, press on the side away from the heart. + + + + +CHAPTER XIII. + +WHY AND HOW WE BREATHE. + + +~1. An Experiment.~--Let us perform a little experiment. We must have a +small bit of candle, a fruit jar, or a bottle with a large mouth, and a +piece of wire about a foot long. Let us notice carefully what we are +about to do and what happens. + +~2.~ We will fasten the candle to the end of the wire. Now we will light +it, and next we will let it down to the bottom of the jar. Now place the +cover on the top of the jar and wait the results. Soon the candle burns +dimly and in a little time the light goes out altogether. + +~3.~ What do you think is the reason that the candle will not burn when +shut up in a bottle? A candle uses air when it burns. If shut up in a +small, tight place, it soon uses up so much air that it can burn no +longer. Try the experiment again, and when the candle begins to burn +dimly, take it out quickly. We see that at once the light burns bright +again. + +~4.~ Suppose we shut the stove draught tight, what is the result? The +fire will burn low, and after a time it will probably go out. Why is +this? Evidently the stove needs air to make the wood or coal burn, just +as the candle needs air to make it burn. + +~5. Animals Die without Air.~--If you should shut up a mouse or any +other small animal in a fruit-jar, its life would go out just as the +light of the candle went out. The little animal would die in a short +time. A child shut up in a close place would die from the same cause in +a very little time. In fact, many children are dying every day for want +of a sufficient supply of pure air. + +~6. Oxygen.~--The reason why animals need air, and why the fire will not +burn without it, is that the air contains _oxygen_, and it is the oxygen +of the air which burns the wood or coal and produces heat. So it is the +oxygen that burns in our bodies and keeps us warm. + +~7.~ When wood and coal are burned, heat is produced; but some parts of +the fuel are not made into heat. While the fire burns, smoke escapes +through the pipe or chimney; but a part of the fuel remains in the stove +in the form of ashes. Smoke and ashes are the waste parts of the fuel. + +~8. Poison in the Breath.~--The burning which takes place in our bodies +produces something similar to the smoke and ashes produced by the fire +in a stove. The smoke is called _carbonic-acid gas_,[A] an invisible +vapor, and escapes through the lungs. The ashes are various waste and +poisonous matters which are formed in all parts of the body. These waste +matters are carried out of the body through the skin, the kidneys, the +liver, and other organs. + +~9. Another Experiment.~--We cannot see the gas escape from our lungs, +but we can make an experiment which will show us that it really does +pass out. Get two drinking-glasses and a tube. A glass tube is best, but +a straw will do very well. Put a little pure water into one glass and +the same quantity of lime-water into the other glass. Now put one end of +the tube into the mouth and place the other end in the pure water. +Breathe through the tube a few times. Look at the water in the glass and +see that no change has taken place. Now breathe through the lime-water +in the same way. After breathing two or three times, you will notice +that the lime-water begins to look milky. In a short time it becomes +almost as white as milk. This is because the lime-water catches the +carbonic-acid gas which escapes from our lungs with each breath, while +the pure water does not. + +~10. Why we Breathe.~--By this experiment we learn another reason why +we breathe. We must breathe to get rid of the carbonic-acid gas, which +is brought to the lungs by the blood to be exchanged for oxygen. There +are two reasons then why we breathe: (_a_) to obtain oxygen; (_b_) to +get rid of carbonic-acid gas. + +~11. How a Frog Breathes.~--Did you ever see a frog breathe? If not, +improve the first opportunity to do so. You will see that the frog has a +very curious way of breathing. He comes to the top of the water, puts +his nose out a little, and then drinks the air. You can watch his throat +and see him swallowing the air, a mouthful at a time, just as you would +drink water. + +~12.~ If you had a chance to see the inside of a frog you would find +there a queer-shaped bag. This is his air-bag. This bag has a tube +running up to the throat. When the frog comes to the surface of the +water he fills this bag with air. Then he can dive down into the mud out +of sight until he has used up the supply of air. When the air has been +changed to carbonic-acid gas, he must come to the surface to empty his +air-bag and drink it full again. + +~13. The Lungs.~--We do not drink air as the frog does, but like the +frog we have an air-bag in our bodies. Our air-bag has to be emptied +and filled so often that we cannot live under water long at a time, as +a frog does. We call this air-bag the lungs. We have learned before that +the lungs are in the chest. We need so much air and have to change the +air in our lungs so often that we would not have time to swallow it as a +frog does. So nature has made for us a breathing apparatus of such a +kind that we can work it like a pair of bellows. Let us now study our +breathing-bellows and learn how they do their work. + +~14. The Windpipe and Air-tubes.~--A large tube called the _windpipe_ +extends from the root of the tongue down the middle of the chest. The +windpipe divides into two main branches, which subdivide again and +again, until the finest branches are not larger than a sewing-needle. +The branches are called _bronchial tubes_. At the end of each tube is a +cluster of small cavities called _air-cells_. The air-tubes and +air-cells are well shown on the following page. + +~15. The Voice-box.~--If you will place the ends of your fingers upon +your throat just above the breast-bone, you will feel the windpipe, and +may notice the ridges upon it. These are rings of cartilage, a hard +substance commonly called gristle. The purpose of these rings is to keep +the windpipe open. Close under the chin you can find something which +feels like a lump, and which moves up and down when you swallow. + +[Illustration: AIR-TUBES AND AIR-CELLS.] + +This is a little box made of cartilage, called the voice-box, because by +means of this curious little apparatus we are able to talk and sing. Two +little white bands are stretched across the inside of the voice-box. +When we speak, these bands vibrate just as do the strings of the piano. +These bands are called the _vocal cords_. + +~16. The Epiglottis.~--At the top of the voice-box is placed a curious +trap-door which can be shut down so as to close the entrance to the +air-passages of the lungs. This little door has a name rather hard to +remember. It is called the _epiglottis_ (ep-i-glot'-tis). The cover of +the voice-box closes whenever we swallow anything. This keeps food or +liquids from entering the air passages. If we eat or drink too fast the +voice-box will not have time to close its little door and prevent our +being choked. Persons have been choked to death by trying to swallow +their food too fast. Do you not think this is a very wonderful door that +can open and shut just when it should do so without our thinking +anything about it? + +~17. The Nostrils and the Soft Palate.~--The air finds its way to the +lungs through the mouth or through the two openings in the nose called +the _nostrils_. From each nostril, three small passages lead backward +through the nose. At the back part of the nasal cavity the passages of +the two sides of the nose come together in an open space, just behind +the soft curtain which hangs down at the back part of the mouth. This +curtain is called the _soft palate_. Through the opening behind this +curtain the air passes down into the voice-box and then into the lungs. + +~18. The Pleura.~--In the chest the air tubes and lung of each side are +enclosed in a very thin covering, called the _pleura_. The cavity of the +chest in which the lungs are suspended is also lined by the pleura. A +limpid fluid exudes from the pleura which keeps it moist, so that when +the two surfaces rub together, as the lungs move, they do not become +chafed and irritated. + +~19. Walls of the Chest.~--The ribs form a part of the framework of the +chest. The ribs are elastic. The spaces between them are filled up with +muscles, some of which draw the ribs together, while others draw them +apart. Can you tell any reason why the walls of the chest are elastic? +The lower wall or floor of the chest cavity is formed by a muscle called +the _diaphragm_, which divides the trunk into two cavities, the chest +and the abdomen. + +~20. How we Use the Lungs.~--Now let us notice how we use the lungs and +what takes place in them. When we use a pair of bellows, we take hold of +the handles and draw them apart. The sides of the bellows are drawn +apart so that there is more room between the sides. The air then rushes +in to fill the space. When the bellows are full, we press the handles +together and the air is forced out. + +~21.~ It is in just this way that we breathe. When we are about to take +a long breath, the muscles pull upon the sides of the chest in such a +way as to draw them apart. At the same time the diaphragm draws itself +downward. By these means, the cavity of the chest is made larger and air +rushes in through the nose or mouth to fill the space. When the muscles +stop pulling, the walls of the chest fall back again to their usual +position and the diaphragm rises. The cavity of the chest then becomes +smaller and the air is forced out through the nose or mouth. This +process is repeated every time we breathe. + +~22.~ We breathe once for each four heart-beats. Small children breathe +more rapidly than grown persons. We usually breathe about eighteen or +twenty times in a minute. + +~23. How Much the Lungs Hold.~--Every time we breathe, we take into our +lungs about two thirds of a pint of air and breathe out the same +quantity. Our lungs hold, however, very much more than this amount. A +man, after he has taken a full breath, can breathe out a gallon of air, +or more than ten times the usual amount. After he has breathed out all +he can, there is still almost half a gallon of air in his lungs which he +cannot breathe out. So you see the lungs hold almost a gallon and a half +of air. + +~24.~ Do you think you can tell why Nature has given us so much more +room in the lungs than we ordinarily use in breathing? If you will run +up and down stairs three or four times you will see why we need this +extra lung-room. It is because when we exercise vigorously the heart +works very much faster and beats harder, and we must breathe much faster +and fuller to enable the lungs to purify the blood as fast as the heart +pumps it into them. + +~25. The Two Breaths.~--We have learned that the air which we breathe +out contains something which is not found in the air which we breathe +in. This is carbonic-acid gas. How many of you remember how we found +this out? We can also tell this in another way. If we put a candle down +in a wide jar it will burn for some time. If we breathe into the jar +first, however, the candle will go out as soon as we put it into the +jar. This shows that the air which we breathe out contains something +which will put a candle out. This is carbonic-acid gas, which is a +poison and will destroy life. + +~26. Other Poisons.~--The air which we breathe out also contains other +invisible poisons which are very much worse than the carbonic-acid gas. +These poisons make the air of a crowded or unventilated room smell very +unpleasant to one who has just come in from the fresh air. Such air is +unfit to breathe. + +~27. The Lungs Purify the Blood.~--We have learned that the blood +becomes dark in its journey through the body. This is because it loses +its oxygen and receives carbonic-acid gas. While passing through the +capillaries of the lungs, the blood gives out the carbonic-acid gas +which it has gathered up in the tissues, and takes up a new supply of +oxygen, which restores its scarlet hue. + +~28. How the Air is Purified.~--Perhaps it occurs to you that with so +many people and animals breathing all the while, the air would after a +time become so filled with carbonic-acid gas that it would be unfit to +breathe. This is prevented by a wonderful arrangement of Nature. The +carbonic-acid gas which is so poisonous to us is one of the most +necessary foods for plants. Plants take in carbonic-acid gas through +their leaves, and send the oxygen back into the air ready for us to use +again. + +~29.~ We have already learned that the oxygen taken in by the lungs is +carried to the various parts of the body by the little blood corpuscles. +The effect of strong liquors is to injure these corpuscles so that they +cannot carry so much oxygen as they ought to do. For this reason, the +blood of a drunkard is darker in color than that of a temperate person, +and contains more carbonic-acid gas. The drunkard's lungs may supply all +the air he needs, but his blood has been so damaged that he cannot use +it. Excessive smoking has a similar effect. + + +SUMMARY. + +1. Our bodies need air, just as a candle or a fire does. + +2. A small animal shut up in a close jar soon dies for want of air. We +need the oxygen which the air contains. + +3. Oxygen causes a sort of burning in our bodies. + +4. The burning in our bodies keeps us warm, and destroys some of the +waste matters. + +5. The breathing organs are the windpipe and bronchial tubes, the +voice-box, the epiglottis, the nostrils, the soft palate, the lungs, the +air-cells, the pleura, the diaphragm, and the chest walls. + +6. When we breathe we use our lungs like a pair of bellows. + +7. A man's lungs hold nearly one and a half gallons of air. + +8. In ordinary breathing we use less than a pint of air, but when + necessary we can use much more. + +9. The air we breathe out contains carbonic-acid gas and another +invisible poison. + +10. A candle will not burn in air which has been breathed, and animals +die when confined in such air. + +11. The lungs purify the blood. While passing through the lungs, the +color of the blood changes from purple to bright red. + +12. Plants purify the air by removing the carbonic-acid gas. + +13. Alcohol and tobacco injure the blood corpuscles so that they cannot +take up the oxygen from the air which the lungs receive. + + + + +CHAPTER XIV. + +HOW TO KEEP THE LUNGS HEALTHY. + + +~1. Pure Air Necessary.~--A person may go without eating for a month, or +without drinking for several days, and still live; but a strong man will +die in a few moments if deprived of air. It is very important that we +breathe plenty of pure air. There are many ways in which the air becomes +impure. + +~2. Bad Odors.~--Anything which rots or decays will in so doing produce +an unpleasant odor. Bad odors produced in this way are very harmful and +likely to make us sick. Many people have rotting potatoes and other +vegetables in their cellars, and swill barrels, and heaps of refuse in +their back yards. These are all dangerous to health, and often give rise +to very serious disease. We should always remember that bad odors caused +by decaying substances are signs of danger to health and life, and that +these substances should be removed from us, or we should get away from +them, as soon as possible. + +~3. Germs.~--The chief reason why bad odors are dangerous is that they +almost always have with them little living things called _germs_. Germs +are so small that they cannot be seen by the naked eye: it takes a +strong microscope to enable us to see them, but they are so powerful to +do harm that if we receive them into our bodies they are likely to make +us very sick, and they often cause death. + +~4. Contagious Diseases.~--You have heard about diphtheria and scarlet +fever and measles, and other "catching diseases." When a person is sick +with one of these diseases, the air about him is poisoned with germs or +something similar, which may give the same disease to other persons who +inhale it. So when a person is sick from one of these diseases, it is +very important that he should be put in a room by himself and shut away +from every one but the doctor and the nurse. It is also necessary that +all the clothing and bedding used by the sick person, and everything in +the room, as well as the room itself, should be carefully cleansed and +disinfected when the person has recovered, so as to wipe out every trace +of the disease. The writer has known many cases in which persons who +have been sick with some of these diseases were careless and gave the +disease to others who died of it, although they themselves recovered. Do +you not think it very wrong for a person to give to another through +carelessness a disease which may cause his death? + +~5.~ Unhealthful vapors and odors of various sorts arise from cisterns +and damp, close places under a house. Rooms which are shaded and shut up +so closely that fresh air and sunshine seldom get into them should be +avoided as dangerous to health. + +~6. Breath-Poisoned Air.~--The most dangerous of all the poisons to +which we are exposed through the air are those of the breath, of which +we learned in a preceding lesson. We need plenty of fresh air to take +the place of the air which we poison by our breath. Every time we +breathe, we spoil at least _half a barrelful of air_. We breathe twenty +times a minute, and hence spoil ten barrels of air in one minute. How +many barrels would this make in one hour? We need an equal quantity of +pure air to take the place of the spoiled air, or not less than ten +barrels every minute, or _six hundred barrels every hour_. + +~7. Ventilation.~--The only way to obtain the amount of fresh air +needed, when we are shut up in-doors, is to have some means provided by +which the fresh air shall be brought in and the old and impure air +carried out. Changing the air by such means is called _ventilation_. +Every house, and especially every sleeping-room, should be well +ventilated. School-houses, churches, and other places where many people +gather, need perfect ventilation. Ask your teacher to show you how the +school-room is ventilated; and when you go home, talk to your parents +about the ventilation of the house in which you live. + +~8.~ Many people ventilate their houses by opening the doors and +windows. This is a very good way of ventilating a house in warm weather, +but is a very poor way in cold weather, as it causes cold draughts, and +makes the floor cold, so that it is difficult to keep the feet warm. It +is much better to have the air warmed by a furnace or some similar +means, before it enters the rooms. There ought also to be in each room a +register to take the foul air out, so that it will not be necessary to +open the windows. This register should be placed at the floor, because +when the pure air enters the room warm, it first rises to the upper part +of the room, and then as it cools and at the same time becomes impure, +it settles to the floor, where it should be taken out by the register. + +~9. How to Breathe.~--We should always take pains to expand the lungs +well in breathing, and to use the entire chest, both the upper and the +lower part. Clothing should be worn in such a way that every portion of +the chest can be expanded. For this reason it is very wrong to wear the +clothing tight about the waist. Clothing so worn is likely to cause the +lungs to become diseased. + +~10. Bad Habits.~--Students are very apt to make themselves flat-chested +and round-shouldered by leaning over their desks while writing or +studying. This is very harmful. We should always use great care to sit +erect and to draw the shoulders well back. Then, if we take pains to +fill the lungs well a great many times every day, we shall form the +habit of expanding the lungs, and shall breathe deeper, even when we are +not thinking about doing so. + +~11. Breathing through the Nose.~--In breathing, we should always take +care to draw the air in through the nose, and not through the mouth. The +nose acts as a strainer, to remove particles of dust which might do harm +if allowed to enter the lungs. It also warms and moistens the air in +cold weather. The habit of breathing through the mouth often gives rise +to serious disease of the throat and lungs. + +~12. Effects of Alcohol and Tobacco upon the Lungs.~--Both alcohol and +tobacco produce disease of the breathing organs. Smoking injures the +throat and sometimes causes loss of smell. Serious and even fatal +diseases of the lungs are often caused by alcohol. + +~13.~ Many people suppose that the use of alcohol will save a man from +consumption. This is not true. A man may become a drunkard by the use of +alcohol, and yet he is more likely to have consumption than he would +have been if he had been a total abstainer. "Drunkard's consumption" is +one of the most dreadful forms of this disease. + + +SUMMARY. + +1. Pure air is as necessary as food and drink. + +2. Anything which is rotting or undergoing decay causes a bad odor, and +thus makes the air impure. + +3. Foul air contains germs which cause disease and often death. + +4. Persons sick with "catching" diseases should be carefully avoided. +Such persons should be shut away from those who are well, and their +rooms and clothing should be carefully cleansed and disinfected. + +5. The breath poisons the air about us. Each breath spoils half a +barrelful of air. + +6. We should change the air in our houses, or ventilate them, so that we +may always have pure air. + +7. We should always keep the body erect, and expand the lungs well in +breathing. + +8. The clothing about the chest and waist should be loose, so that the +lungs may have room to expand. + +9. Always breathe through the nose. + +10. Tobacco causes disease of the throat and nose. + +11. Alcohol causes consumption and other diseases of the lungs. + + + + +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. + +[Illustration: 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. + +[Illustration: 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. + +[Illustration: 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. + +[Illustration: 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. + + { Ribs. + _b._ The trunk. { Breast-bone. + { Pelvis. + { Back-bone. + { Collar-bone. + { Shoulder-blade. + + { Upper arm-bones. + _c._ The arms. { Lower arm-bones. + { Wrist. + { Hand and fingers. + + { Thigh. + { Knee-pan. + _d._ The legs. { Lower-leg bones. + { Ankle, including heel-bone. + { Foot and toes. + +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. + +[Illustration: 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. + +[Illustration: 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. + +[Illustration: 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. + +[Illustration: 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. + + + + +CHAPTER XX. + +THE MUSCLES AND HOW WE USE THEM. + + +~1. The Muscles.~--Where do people obtain the beefsteak and the +mutton-chops which they eat for breakfast? From the butcher, you will +say; and the butcher gets them from the sheep and cattle which he kills. +If you will clasp your arm you will notice that the bones are covered by +a soft substance, the flesh. When the skin of an animal has been taken +off, we can see that some of the flesh is white or yellow and some of it +is red. The white or yellow flesh is fat. The red flesh is lean meat, +and it is composed of muscles. + +~2. The Number of Muscles.~--We have about five hundred different +muscles in the body. They are arranged in such a way as to cover the +bones and make the body round and beautiful. They are of different forms +and sizes. + +~3.~ With a very few exceptions the muscles are arranged in pairs; that +is, we have two alike of each form and size, one for each side of the +body. + +~4. How a Muscle is Formed.~--If you will examine a piece of corned or +salted beef which has been well boiled, you will notice that it seems to +be made up of bundles of small fibres or threads of flesh. With a little +care you can pick one of the small fibres into fine threads. Now, if you +look at one of these under a microscope you find that it is made of +still finer fibres, which are much smaller than the threads of a +spider's web. One of these smallest threads is called a _muscular +fibre_. Many thousands of muscular fibres are required to make a muscle. + +[Illustration: MUSCULAR FIBRES.] + +~5.~ Most of the muscles are made fast to the bones. Generally, one end +is attached to one bone, and the other to another bone. Sometimes one +end is made fast to a bone and the other to the skin or to other +muscles. + +~6. The Tendons.~--Many of the muscles are not joined to the bones +directly, but are made fast to them by means of firm cords called +_tendons_. If you will place the thumb of your left hand upon the wrist +of the right hand, and then work the fingers of the right hand, you may +feel these cords moving underneath the skin. + +~7. What the Muscles Do.~--With the left hand grasp the right arm just +in front of the elbow. Now shut the right hand tightly. Now open it. +Repeat several times. The left hand feels something moving in the flesh. +The motion is caused by the working of the muscles, which shorten and +harden when they act. + +~8.~ All the movements of the body are made by means of muscles. When we +move our hands, even when we close the mouth or the eyes, or make a wry +face, we use the muscles. We could not speak, laugh, sing, or breathe +without muscles. + +~9. Self-acting Muscles.~--Did you ever have a fit of sneezing or +hiccoughing? If you ever did, very likely you tried hard to stop but +could not. Do you know why one cannot always stop sneezing or +hiccoughing when he desires to do so? It is because there are certain +muscles in the body which do not act simply when we wish them to act, +but when it is necessary that they should. The muscles which act when we +sneeze or hiccough are of this kind. The arm and the hand do not act +unless we wish them to do so. Suppose it were the same with the heart. +We should have to stay awake all the while to keep it going, because it +would not act when we were asleep. The same is true of our breathing. We +breathe when we are asleep as well as when we are awake, because the +breathing muscles work even when we do not think about them. + +~10.~ The stomach, the intestines, the blood-vessels, and many other +organs within the body have this kind of muscles. The work of these +self-acting muscles is very wonderful indeed. Without it we could not +live a moment. This knowledge should lead us to consider how dependent +we are, each moment of our lives, upon the delicate machinery by which +the most important work of our bodies is performed, and how particular +we should be to keep it in good order by taking proper care of +ourselves. + + +SUMMARY. + +1. The flesh, or lean meat, is composed of muscles. + +2. There are five hundred muscles in the body. + +3. Muscles are composed of many small threads called muscular fibres. + +4. Many of the muscles are joined to the bones by strong white cords +called tendons. + +5. Muscular fibres can contract so as to lessen their length. It is in +this way that the muscles perform their work. + +6. All bodily motions are due to the action of the muscles. + +7. Most of the muscles act only when we wish them to do so. Some +muscles, however, act when it is necessary for them to do so, whether we +will that they should act or not, and when we are asleep as well as when +we are awake. + + + + +CHAPTER XXI. + +HOW TO KEEP THE MUSCLES HEALTHY. + + +~1. How to Make the Muscles Strong.~--With which hand can you lift the +more? with the right hand or with the left? Why do you think you can +lift more with the right hand than with the left? A blacksmith swings a +heavy hammer with his right arm, and that arm becomes very large and +strong. If we wish our muscles to grow large and strong, so that our +bodies will be healthy and vigorous, we must take plenty of exercise. + +~2. Effects of Idleness.~--If a boy should carry one hand in his pocket +all the time, and use only the other hand and arm, the idle arm would +become small and weak, while the other would grow large and strong. Any +part of the body which is not used will after a time become weak. Little +boys and girls who do not take plenty of exercise are likely to be pale +and puny. It is important that we should take the proper amount of +exercise every day, just as we take our food and drink every day. + +~3. Healthful Exercise.~--Some kinds of play, and almost all kinds of +work which children have to do, are good ways of taking exercise. A very +good kind of exercise for little boys and girls is that found in running +errands or doing chores about the house. + +~4. Food and Strength.~--A great part of our food goes to nourish the +muscles. Some foods make us strong, while others do not. Plain foods, +such as bread, meat, potatoes, and milk, are good for the muscles; but +cakes and pies, and things which are not food, such as mustard, pepper, +and spices, do not give us strength, and are likely to do us harm. + +~5. Over-Exertion.~--We ought not to exert ourselves too much in lifting +heavy weights, or trying to do things which are too hard for us. +Sometimes the muscles are permanently injured in this way. + +~6. The Clothing.~--We ought not to wear our clothing so tight as to +press hard upon any part of the body. If we do, it will cause the +muscles of that part to become weak. If the clothing is worn tight about +the waist, great mischief is often done. The lungs cannot expand +properly, the stomach and liver are pressed out of shape, and the +internal organs are crowded out of their proper places. + +~7. Tight Shoes.~--People are often made very lame from wearing tight +shoes. Their muscles cannot act properly, and their feet grow out of +shape. + +~8.~ In China, it is fashionable for rich ladies to have small feet, and +they tie them up in cloths so that they cannot grow. The foot is +squeezed out of shape. Here is a picture of a foot which has been +treated in this way. It does not look much like a human foot, does it? A +woman who has such feet finds it so difficult to walk that she has to be +carried about much of the time. Do you not think it is very wrong and +foolish to treat the feet so badly? You will say, "Yes;" but the Chinese +woman thinks it is a great deal worse to lace the clothing tight about +the body so as to make the waist small. + +[Illustration: FOOT OF CHINESE WOMAN.] + +~9. Effects of Alcohol upon the Muscles.~--When an intemperate man takes +a glass of strong drink, it makes him feel strong; but when he tries to +lift, or to do any kind of hard work, he cannot lift so much nor work so +hard as he could have done without the liquor. This is because alcohol +poisons the muscles and makes them weak. + +~10. Effects of Drunkenness.~--When a man has become addicted to strong +drink, his muscles become partly paralyzed, so that he cannot walk as +steadily or speak as readily or as clearly as before. His fingers are +clumsy, and his movements uncertain. If he is an artist or a jeweller, +he cannot do as fine work as when he is sober. When a man gets very +drunk, he is for a time completely paralyzed, so that he cannot walk or +move, and seems almost like a dead man. + +~11.~ If you had a good horse that had carried you a long way in a +carriage, and you wanted to travel farther, what would you do if the +horse were so tired that he kept stopping in the road? Would you let him +rest and give him some water to drink and some nice hay and oats to eat, +or would you strike him hard with a whip to make him go faster? If you +should whip him he would act as though he were not tired at all, but do +you think the whip would make him strong, as rest and hay and oats +would? + +~12.~ When a tired man takes alcohol, it acts like a whip; it makes +every part of the body work faster and harder than it ought to work, and +thus wastes the man's strength and makes him weaker, although for a +little while his nerves are made stupid, so that he does not know that +he is tired and ought to rest. + +~13.~ When you grow up to be men and women you will want to have strong +muscles. So you must be careful not to give alcohol a chance to injure +them. If you never taste it in any form you will be sure to suffer no +harm from it. + +~14. Effects of Tobacco on the Muscles.~--Boys who smoke cigars or +cigarettes, or who chew tobacco, are not likely to grow up to be strong +and healthy men. They do not have plump and rosy cheeks and strong +muscles like other boys. + +~15.~ The evil effect of tobacco upon boys is now so well known that in +many countries and in some states of this country laws have been made +which do not allow alcohol or tobacco to be sold or given to boys. In +Switzerland, if a boy is found smoking upon the streets, he is arrested +just as though he had been caught stealing. And is not this really what +a boy does when he smokes? He robs his constitution of its vigor, and +allows tobacco to steal away from him the strength he will need when he +becomes a man. + +~16. Tea and Coffee.~--Strong tea and coffee, while by no means so bad +as alcohol and tobacco, may make us weak and sick. A person who drinks +strong tea or coffee feels less tired while at work than if he had not +taken it, but he is more tired afterwards. So you see that tea and +coffee are also whips, small whips we might call them, and yet they +really act in the same way as do other narcotics and stimulants. They +make a person feel stronger than he really is, and thus he is led to use +more strength than he can afford to do. + + +SUMMARY. + +1. We must use the muscles to make them grow large and strong. + +2. Exercise should be taken regularly. + +3. Exercise makes the muscles strong, the body beautiful, the lungs +active, the heart vigorous, and the whole body healthy. + +4. Things we ought not to do: To run or play hard just before or after +eating; to strain our muscles by lifting too heavy weights; to exercise +so violently as to get out of breath; to lie, sit, stand, or walk in a +cramped position, or awkward manner; to wear the clothing so tight as to +press hard upon the muscles. + +5. Good food is necessary to make the muscles strong and healthy. + +6. Alcohol makes the muscles weak, although at first it makes us feel +stronger. + +7. A boy who uses tobacco will not grow as strong and well as one who +does not. + +8. The use of strong tea and coffee may injure the muscles. + + + + +CHAPTER XXII. + +HOW WE FEEL AND THINK. + + +~1. How we Think.~--With what part of the body do we think? You will at +once say that we think with the head; but we do not think with the whole +head. Some parts of the head we use for other purposes, as the mouth to +eat and speak with, and the nose to smell and breathe with. The part we +think with is inside of the skull, safely placed in a little room at the +top and back part of the head. Do you remember the name of this organ +which fills the hollow place inside of the skull? We learned some time +ago that it is called the _brain_. It is with the brain that we study +and remember and reason. So the brain is one of the most important +organs in our body, and we must try to learn all we can about it. + +~2. The Brain.~--You cannot see and examine your own brain because it is +shut up in the skull; but perhaps you can find the brain of a sheep or a +calf at the meat market. The brain of one of these animals looks very +nearly like your own. + +~3. The Large Brain and the Small Brain.~--In examining a brain we +should notice first of all that there are really two brains, a _large +brain_ and a _small brain_. The large brain is in the top and front of +the skull, and the small one lies beneath the back part of the larger +one, If we look again we shall see that each brain is divided in the +middle into a right and a left half. Each half is, in fact, a complete +brain, so that we really have two pairs of brains. + +[Illustration: THE BRAIN.] + +~4. Brain Cells.~--The brain is a curious organ of a grayish color +outside and white inside. It is soft, almost like jelly, and this is why +it is placed so carefully in a strong, bony box. If we should put a +little piece of the brain under a microscope, we should find that it is +made up of a great number of very small objects called _nerve_ or +_brain cells_. In the illustration you can see some of these brain +cells. + +[Illustration: BRAIN CELLS.] + +~5. The Nerves.~--Each cell has one or more branches. Some of the +branches are joined to the branches of other cells so as to unite the +cells together, just as children take hold of one another's hands. Other +branches are drawn out very long. + +~6.~ The long branches are such slender threads that a great number of +them together would not be as large as a fine silk thread. A great many +of these fine nerve threads are bound up in little bundles which look +like white cords. These are called _nerves_. + +~7.~ The nerves branch out from the brain through openings in the skull, +and go to every part of the body. Every little muscle fibre, the heart, +the stomach, the lungs, the liver, even the bones--all have nerves +coming to them from the brain. So you see that the brain is not wholly +shut up in the skull, because its cells have slender branches running +into all parts of the body; and thus the brain itself is really in every +part of the body, though we usually speak of it as being entirely in the +skull. + +~8. The Spinal Cord.~--There are a number of small holes in the skull +through which the nerves pass out, but most of the nerves are bound up +in one large bundle and pass out through an opening at the back part of +the skull and runs downward through a long canal in the backbone. This +bundle of nerves forms the _spinal cord_. The spinal cord contains cells +also, like those of the brain. It is really a continuation of the brain +down through the backbone. + +[Illustration: BRAIN AND SPINAL CORD.] + +~9. Nerves from the Spinal Cord.~--The spinal cord gives off branches of +nerves which go to the arms, the chest, the legs, and other parts. One +of the branches which goes to the hand runs along the back side of the +arm, passing over the elbow. If we happen to strike the elbow against +some sharp object, we sometimes hit this nerve. When we do so, the under +side of the arm and the little finger feel very numb and strange. This +is why you call this part of the elbow the "funny" or "crazy bone." The +cells of the spinal cord also send out branches to the body and to other +cells in the brain. + +~10. How we Feel.~--If we cut or burn ourselves we suffer pain. Can you +tell why it hurts us to prick the flesh with a pin, or to pinch or burn +or bruise it? It is because the flesh contains a great many +nerve-branches from the brain. When we hurt the skin or the flesh, in +any way, these nerves are injured. There are so many of these little +nerves in the flesh and skin that we cannot put the finest needle into +the flesh without hurting some of them. + +~11. The Use of Pain.~--It is not pleasant for us to have pain, but if +the nerves gave us no pain when we are hurt we might get our limbs +burned or frozen and know nothing about it until too late to save them. + +~12. Nerves of Feeling.~--We have different kinds of nerves of feeling. +Those we have learned about feel pain. Others feel objects. If you take +a marble or a pencil in the hand you know what it is by the feeling of +the object. This kind of feeling is called the sense of touch. + +~13.~ There are other nerves of feeling by means of which we are able to +hear, see, taste, and smell, of which we shall learn in another lesson. +Besides these we have nerves which tell us whether objects are cold or +hot, and heavy or light. Nerves of feeling also tell us when we are +hungry, or thirsty, or tired, and when we need more air to breathe. + +~14. Nerves of Work.~--There are other nerves which are made just like +the nerves of feeling, but which do not feel. These nerves have a very +different use. They come from cells in the brain which have charge of +the different kinds of work done in the body, and they send their +branches to the parts which do the work; hence we call them _nerves of +work_. + +~15.~ One set of cells sends nerves to the heart, and these make it go +fast or slow as is necessary. Another sends nerves to the liver, +stomach, and other digestive organs, and causes them to do their part in +the digestion of the food. Other cells send branches to the muscles and +make them act when we wish them to do so. Thus you see how very useful +the brain and nerves are. They keep all the different parts of the body +working together in harmony, just like a well-trained army, or a great +number of workmen building a block of houses. Without the brain and +nerves the body would be just like an army without a commander, or a lot +of workmen without an overseer. + +~16. How we Use the Nerves.~--If you happen to touch your hand to a hot +stove, what takes place? You will say that your arm pulls the hand away. +Do you know why? Let us see. The nerves of feeling in the hand tell the +nerve cells in the brain from which they come that the hand is being +burned. The cells which feel cannot do anything for the hand, but some +of their branches run over to another part of the brain, which sends +nerves down to the muscles of the arm. These cells, through their nerve +branches, cause the muscles to contract. The cells of feeling ask the +cells which have charge of the muscles to make the muscles of the arm +pull the hand away, which they do very quickly. + +~17.~ So you see the nerves are very much like telegraph or telephone +wires. By means of them the brain finds out all about what is happening +in the body, and sends out its orders to the various organs, which may +be called its servants. + +~18. An Experiment.~--A man once tried an experiment which seemed very +cruel. He took a dove and cut open its skull and took out its large +brain. What do you think the effect was? The dove did not die at once, +as you would expect. It lived for some time, but it did not know +anything. It did not know when it was hungry, and would not eat or drink +unless the food or water was placed in its mouth. If a man gets a blow +on his head, so hard as to break his skull, the large brain is often +hurt so badly that its cells cannot work, and so the man is in the same +condition as the poor dove. He does not know anything. He cannot think +or talk, and lies as though he were asleep. + +~19.~ By these and many other facts we know that the large brain is the +part with which we remember, think, and reason. It is the seat of the +mind. We go to sleep because the large brain is tired and cannot work +any longer. We stop thinking when we are sound asleep, but sometimes we +do not sleep soundly, and then the large brain works a little and we +dream. + +~20. What the Little Brain Does.~--The little brain[B] thinks too, but +it does not do the same kind of thinking as the large brain. We may use +our arms and legs and many other parts when we wish to do so; and if we +do not care to use them we may allow them to remain quiet. This is not +the case with some other organs. It is necessary, for example, that the +heart, the lungs, and many other organs of the body should keep at work +all the time. If the large brain had to attend to all of these +different kinds of work besides thinking about what we see, hear, and +read, and other things which we do, it would have too much work to do, +and would not be able to do it all well. Besides, the large brain +sometimes falls asleep. So the large brain lets the little brain do the +kinds of work which have to be attended to all the time, and the little +brain keeps steadily at work when we are asleep as well as when we are +awake. + +~21. What the Spinal Cord Does.~--If you tickle a person's foot when he +is asleep, he will pull it up just as he would if he were awake, only +not quite so quickly. What do you suppose makes the muscles of the leg +contract when the brain is asleep and does not know that the foot is +being tickled? And here is another curious fact. When you were coming to +school this morning you did not have to think about every step you took. +Perhaps you were talking or looking over your lessons; but your legs +walked right along all the time, and without your thinking about them. +Can you tell how? + +~22.~ It would be too much trouble for the large brain to stop to think +every time we step, and the little brain has work enough to do in taking +care of the heart and lungs and other organs, without keeping watch of +the feet when we are asleep, so as to pull them up if some mischievous +person tickles them. So Nature puts a few nerve cells in the spinal cord +which can do a certain easy kind of thinking. When we do things over and +over a great many times, these cells, after a time, learn to do them +without the help of the large brain. This is the way a piano-player +becomes so expert. He does not have to think all the time where each +finger is to go. After the tunes have been played a great many times, +the spinal cord knows them so well that it makes the hands play them +almost without any effort of the large brain. + + +SUMMARY. + +1. The part of the body with which we think is the brain. + +2. The brain is found filling the hollow place in the skull. + +3. There are two brains, the large brain and the small brain. + +4. Each brain is divided into two equal and complete halves, thus making +two pairs of brains. + +5. The brain is largely made up of very small objects called nerve or +brain cells. + +6. The nerve cells send out very fine branches which form the nerves. + +7. The nerve branches or fibres run to every part of the body. They pass +out from the brain to the rest of the body through a number of openings +in the skull. + +8. Most of the nerve branches pass out through a large opening at the +back of the skull, in one large bundle called the spinal cord. + +9. The spinal cord runs down through a canal in the backbone, and all +along gives off branches to the various parts of the body. + +10. It gives us pain to prick or hurt the flesh in any way, because when +we do so we injure some of the little nerve branches of the brain cells. + +11. When we suffer, we really feel a pain in the brain. We know this +because if a nerve is cut in two, we may hurt the part to which it goes +without giving any pain. + +12. We have different kinds of nerves of feeling. + +13. There are other nerves besides those of feeling. These are nerves of +work. + +14. The nerves of work have charge of the heart, the lungs, the muscles, +the liver, the stomach, and every part of the body which can work or +act. + +15. The brain and nerves control the body and make all the different +parts work together in harmony, just as a general controls an army. + +16. The brain uses the nerves very much as a man uses the telephone or +telegraph wires. + +17. With the large brain we remember, think, and reason. + +18. The little brain does the simple kind of thinking, by means of which +the heart, lungs, and other vital organs are kept at work even when we +are asleep. + +19. The spinal cord does a still more simple kind of work. It enables us +to walk and to do other familiar acts without using the large brain to +think every moment just what we are doing. + + + + +CHAPTER XXIII. + +HOW TO KEEP THE BRAIN AND NERVES HEALTHY. + + +~1. Uses of the Brain.~--What do you think a boy or girl would be good +for without any brain or nerves? Such a boy or girl could not see, hear, +feel, talk, run about, or play, and would not know any more than a +cabbage or a potato knows. If the brain or nerves are sick, they cannot +work well, and so are not worth as much as when they are healthy. + +~2. The Brain Sympathizes with Other Organs.~--Did you ever have a +headache? Did you feel happy and good-natured when your head ached hard, +and could you study and play as well as when you are well? It is very +important that we should keep our brain and nerves healthy, and to do +this we must take good care of the stomach and all other organs, because +the brain sympathizes with them when they are sick. + +~3. We must have Pure Air.~--How do you feel when the school-room is too +warm and close? Do you not feel dull and sleepy and so stupid that you +can hardly study? This is because the brain needs good, pure blood to +enable it to work well. So we must always be careful to have plenty of +pure air to breathe. + +~4. We should Exercise the Brain.~--What do we do when we want to +strengthen our muscles? We make them work hard every day, do we not? The +exercise makes them grow large and strong. It is just the same with our +brains. If we study hard and learn our lessons well, then our brains +grow strong, and study becomes easy. But if we only half study, and do +not learn our lessons perfectly, then the study does not do our brains +very much good. + +~5. We should Take Muscular Exercise.~--When you get tired of study, an +hour's play, or exercise of some sort, rests you and makes you feel +brighter, so that you can learn more easily. This is because exercise is +necessary to make the blood circulate well. It will then carry out the +worn-out particles and supply the brain and nerves with fresh, pure +blood. So the same exercise which makes our muscles strong makes our +brains healthier also. + +~6. We should be Careful of our Diet.~--We ought to eat plenty of good, +simple food, such as milk, fruits, grains, and vegetables. It is not +well for children to eat freely of meat, as it is very stimulating and +likely to excite the brain and make the nerves irritable. Mustard, +pepper, and all hot sauces and spices have a tendency to injure the +brain and nerves. + +~7. We should Allow the Brain to Rest at the Proper Time.~--When we are +tired and sleepy we cannot think well, and cannot remember what we learn +if we try to study. If we have plenty of sleep, free from bad or +exciting dreams, we awake in the morning rested and refreshed, because +while we have been asleep Nature has put the brain and nerves in good +repair for us. We ought not to stay up late at night. We should not eat +late or hearty suppers, as this will prevent our sleeping well. + +~8. We Ought Not to Allow Ourselves to Become Angry.~--When a person +flies into a passion he does his brain and nerves great harm. It is +really dangerous to get angry. Persons have dropped dead instantly in a +fit of anger. + +~9. We should Shun Bad Habits.~--Bad habits are very hard to give up, +and hence we should be careful to avoid them. When a child learns to +swear, or to use slang phrases, the brain after a while will make him +swear or use bad words before he thinks. In a similar manner other bad +habits are acquired. + + +SUMMARY. + +1. A person without a brain or nerves would be of no more account than a +vegetable. + +2. When the brain or nerves are sick they cannot perform their duties +properly. + +3. To keep the brain and nerves in good health, we must take good care +of the stomach and all other important organs of the body. + +4. There are many things which we may do to keep the brain and nerves +strong and well. + +5. The brain needs pure blood, and so we must be careful to breathe pure +air. + +6. The brain gets strength by exercise, just as the muscles do. Hence, +study is healthful, and makes the brain strong. + +7. A good memory is very necessary, but we should not try to remember +everything. + +8. It is very important that we learn how to observe things closely. + +9. Exercise in the open air rests and clears the brain by helping the +blood to circulate. + +10. Plenty of wholesome and simple food is necessary to keep the brain +and nerves in good health. Spices, condiments, and rich foods in general +are stimulating and harmful. + +11. Plenty of sleep is needed to rest the brain and nerves. + +12. It is dangerous as well as wicked to become very angry. + +13. We should be careful to avoid forming bad habits of any sort, as +they are hard to break, and often adhere to one through life. + + + + +CHAPTER XXIV. + +BAD EFFECTS OF ALCOHOL UPON THE BRAIN AND NERVES. + + +~1. Drunkenness.~--Did you ever see a man who was drunk? If you live in +a city it is very likely that you have. How did the drunken man behave? +Perhaps he was noisy and silly. Perhaps he was angry and tried to pick a +quarrel with some one. + +~2.~ What made the man drunk? You say whiskey, but it may have been +wine, or beer, or hard cider that he drank. Anything that contains +alcohol will make a man drunk, for it is the alcohol which does all the +mischief. + +~3. The Whiskey Flush.~--You can almost always tell when a man has been +drinking, even when he has not taken enough to make him drunk. You know +by his flushed face and red eyes. When a man's face blushes from the use +of alcohol, his whole body blushes at the same time. His muscles, his +lungs, and his liver blush; his brain and spinal cord blush also. + +~4.~ When a man has taken just enough alcohol to make his face blush a +little, the extra amount of blood in the brain makes him think and talk +more lively, and he is very jolly and gay. This makes many people think +that alcohol does them good. But if we notice what a man says when he is +excited by alcohol, we shall find that his remarks are often silly and +reckless. He says very unwise and foolish things, for which he feels +sorry when he becomes sober. + +~5. Alcohol Paralyzes.~--How does a drunken man walk? Let us see why he +staggers. When a man takes a certain amount of alcohol his small brain +and spinal cord become partly paralyzed, so that they cannot do their +duty well; and so, when he tries to walk he reels and stumbles along, +often falling down, and sometimes hurting himself very much. The fact is +that the alcohol has put his spinal cord and small brain to sleep so +that he cannot make his legs do what he wants them to do. Now, if still +more alcohol is taken the whole brain becomes paralyzed, and then the +man is so nearly dead that we say he is "dead drunk." It is exceedingly +dangerous to become dead drunk, as the brain may be so completely +paralyzed that it will not recover. + +~6.~ A small amount of alcohol does not make a man dead drunk, but it +poisons and paralyzes his brain and nerves just according to the +quantity he takes. + +~7.~ If a person holds a little alcohol in his mouth for a few moments, +the tongue and cheeks feel numb. This is because the alcohol paralyzes +them so that they cannot feel or taste. When taken into the stomach it +has much the same kind of effect upon the nerves of the whole body. + +~8. Alcohol a Deceiver.~--A hungry man takes a drink of whiskey and +benumbs the nerves of his stomach so that he does not feel hungry. +Alcohol puts to sleep the sentinels which Nature has set in the body to +warn us of danger. A man who is cold takes alcohol and feels warm, +though he is really colder. He lies down in his false comfort and +freezes to death. A tired man takes his glass of grog and feels rested +and strong, though he is really weaker than before. A poor man gets +drunk and feels so rich that he spends what little money he has. The +alcohol paralyzes his judgment and steals away his good sense. Thus +alcohol is always a deceiver. + +~9. Delirium Tremens.~ (De-lir'-i-um Tre'-mens.)--When a man takes +strong liquors regularly he very soon injures his brain and nerves so +that they do not get quiet, as they should, at night, and he does not +sleep well. He has frightful dreams. He sees all sorts of wild animals +and horrid shapes in his dreams. Perhaps you have sometimes had such +dreams from eating late suppers or indigestible food. + +~10.~ Did you ever have a dream when you were awake? If a man drinks a +great deal he is likely to have a terrible disease known as _delirium +tremens_, in which he sees the same frightful things when he is wide +awake that he dreams about when he is asleep. This is one of the +terrible effects of alcohol upon the brain and nerves. + +~11. Alcohol Paralysis.~--You have seen how a drunken man staggers when +he walks. Did you ever see a man who walked just as though he were drunk +when he was really sober? This is because a part of the brain or spinal +cord has been permanently injured or paralyzed. Alcohol is not the only +cause of this disease, and so you must not think every person who +staggers is or has been a drunkard; but alcohol is a very frequent cause +of paralysis. + +~12. Effects of Alcohol upon the Mind and Character.~--When a man is +under the influence of alcohol is his character good or bad? Is a man +likely to be good, or to be bad, when he is drunk or excited by drink? +Most men behave badly when they are drunk, and after they have been +drunk a great many times they often behave badly all the time. A great +many of the men who are shut up in prisons would not have been sent +there if they had never learned to drink. + +~13. A Legacy.~--Do you know what a legacy is? If your father should die +and leave to you a fine house or farm, or money in the bank, or books, +or horses, or any other kind of property to have for your own, it would +be a legacy. When a person gets anything in this way from a parent we +say that he inherits it. + +~14.~ We inherit a great many things besides houses and lands and other +kinds of property. For instance, perhaps you remember hearing some one +say that you have eyes and hair the same color as your mother's, and +that your nose and chin are like your father's. So you have inherited +the color of your hair and eyes from your mother and the shape of your +chin and nose from your father. + +~15. The Alcohol Legacy.~--The inside of a boy's head is just as much +like his parents' as the outside of it. In other words, we inherit our +brains just as we do our faces. So, if a man spoils his brain with +alcohol and gets an alcohol appetite, his children will be likely to +have unhealthy brains and an appetite for alcohol also, and may become +drunkards. Is not that a dreadful kind of legacy to inherit? + +~16.~ A child that has no mind is called an idiot. Such a child cannot +talk, or read, or sing, and does not know enough to take proper care of +itself. This is one of the bad legacies which drunken parents sometimes +leave to their children. + +~17. Effects of Tobacco on the Brain and Nerves.~--The effects of +tobacco upon the brain and nerves are much the same as those of alcohol. +Tobacco, like alcohol, is a narcotic. It benumbs and paralyzes the +nerves, and it is by this means that it obtains such an influence over +those who use it. + +~18.~ The hand of a man or boy who uses tobacco often becomes so +unsteady that he can scarcely write. Do you know what makes it so +unsteady? It is because the cells which send nerves to the muscles of +the hand are diseased. When a person has a trembling hand you say he is +nervous. If you feel his pulse you will find that it does not beat +steadily and regularly as it ought to do. The heart is nervous and +trembles just the same as the muscles do. This shows that the tobacco +has poisoned the cells in the brain which regulate the heart. + +~19.~ Wise physicians will tell you that one reason why tobacco is bad +for boys is that it hurts their brains so that they cannot learn well, +and do not become as useful and successful men as they might be. + +~20.~ Students in the naval and military schools of this country are not +allowed to use tobacco on account of its bad effects upon the mind. In +France the use of tobacco is forbidden to all students in the public +schools. + +~21. Tobacco Leads to Vice.~--Boys who use tobacco are more liable to +get into company with boys who have other bad habits, and so are apt to +become bad in many other ways. The use of tobacco often makes men want +strong drink, and thus leads to drunkenness. If you wish to grow up with +a steady hand, a strong heart, and a good character you will never touch +tobacco. + +~22. Effects of Tea and Coffee on the Nerves.~--People who use strong +tea and coffee are often inclined to be nervous. This shows that strong +tea and coffee, like alcohol and tobacco, are very injurious to the +nerves. + +~23. Opium, Chloral, etc.~--There are several drugs which are given by +physicians to relieve pain or to produce sleep. They are sometimes +helpful, but their use is very dangerous. Opium and chloral belong to +this class of medicines. The danger is that, after a person has used the +medicine a little while, he will continue to use it. If a person takes a +poisonous drug every time he has a little pain, he will soon form the +habit of using it, and may never break it off. There are many thousands +of people who use opium all the time, and they are very much injured by +it in mind and body. The mind becomes dull and stupid and the body weak +and feeble. No medicine of this sort should ever be taken unless +prescribed by a physician. + + +SUMMARY. + +1. In order to be well and useful we must keep the brain and nerves +healthy. + +2. To keep the brain healthy we need plenty of pure air to breathe; +proper exercise of the brain by study; sufficient exercise of the +muscles in play and work; plenty of good food to make pure blood; a +proper amount of rest and sleep. + +3. There are several things we ought not to do. We should not read or +study too much. We should not allow ourselves to become excited or +angry. We should avoid learning bad habits. + +4. Alcohol paralyzes the brain and nerves. + +5. Alcohol deceives a person who takes it by making him feel strong when +he is weak; warm when he is cold; rich when he is poor; well when he is +sick. + +6. Alcohol makes men wicked. Most men who commit crimes are men who use +liquor. + +7. The effects of tobacco upon the brain and nerves are much the same as +those of alcohol. Tobacco is very injurious to the mind. + +8. Tobacco-using often leads boys to drunkenness and other vices. + +9. The use of opium and chloral produces even worse effects than the use +of alcohol or tobacco. + + + + +CHAPTER XXV. + +HOW WE HEAR, SEE, SMELL, TASTE, AND FEEL. + + +~1. The Senses.~--We have five senses--_hearing_, _seeing_, _smelling_, +_tasting_, and _feeling_. These are called special senses because they +are very different from each other. They also differ from the general +sense of feeling by means of which we feel pain when any part is hurt. + +~2. Organs of the Special Senses.~--Each of the special senses has a +special set of nerves and also special cells in the brain which have +charge of them. We say that we see with our eyes, hear with our ears, +feel with our fingers, etc.; but, really, we see, hear, taste, and smell +in the brain just as we feel in the brain. The eyes, ears, nose, and +other organs of the special senses are the instruments by means of which +the brain sees, hears, smells, etc. + +~3. Sound and the Vibrations which it Causes.~--All sounds are made by +jars or vibrations of objects. Sounds cause objects to vibrate or +tremble. A loud sound sometimes jars a whole house, while other sounds +are so gentle and soft that we cannot feel them in the same way that we +feel loud sounds. But Nature has made for us an ingenious organ by means +of which we can feel these very fine vibrations as well as loud ones. We +call this organ the _ear_. + +~4. The Ear.~--The part of the ear which we can see is shaped somewhat +like a trumpet. The small opening near the middle of the ear leads into +a _canal_ or tube which extends into the head about an inch. At the +inner end there is a curious little chamber. This is called the _drum_ +of the ear, because between it and the canal of the ear there is +stretched a thin membrane like the head of a drum. The ear-drum is also +called the _middle ear_. + +[Illustration: THE EAR.] + +~5. Bones of the Ear.~--Within the drum of the ear there are three +curious little bones which are joined together so as to make a complete +chain, reaching from the drum-head to the other side of the drum. The +last bone fits into a little hole which leads into another curious +chamber. This chamber, which is called the _inner ear_, is filled with +fluid, and in this fluid the nerve of hearing is spread out. A part of +the inner ear looks very much like a snail shell. + +[Illustration: THE INSIDE OF THE EAR.] + +~6. How we Hear.~--Scratch with a pin upon one end of a long wooden +pole. Have some one listen with the ear placed close against the other +end of the pole. He will tell you that he hears the scratching of the +pin very plainly. This is because the scratching jars the ear and +especially the drum-head, which vibrates just as the head of a drum does +when it is beaten with a drum-stick. When the drum-head vibrates it +moves the bones of the ear, and these carry the vibration to the nerves +of hearing in the inner chamber. We hear all sounds in the same way, +only most sounds come to the ear through the air. + +The snail-shell of the inner part of the ear hears musical sounds. The +rest of the inner ear hears ordinary sounds or noises. + +~7. How to Keep the Ears Healthy.~--The ears are very delicate organs +and must be carefully treated. The following things about the care of +the ears should never be forgotten: + +(1.) Never use a pin, toothpick, or any other sharp instrument to clean +out the ear. There is great danger that the drum-head will be torn, and +thus the hearing will be injured. Neither is it ever necessary to use an +ear-spoon to remove the wax. Working at the ear causes more wax to form. + +(2.) Do not allow cold water to enter the ear or a cold wind to blow +directly into it. + +(3.) If anything accidentally gets into the ear, do not work at it, but +hold the head over to one side while water is made to run in from a +syringe. If an insect has gone into the ear, pour in a little oil. This +will kill the insect or make it come out. + +(4.) Never shout into another person's ear. The ear may be greatly +injured in this way. + +(5.) Boxing or pulling the ears is likely to produce deafness, and ought +never to be done. + +~8. The Eye.~--The eye is one of the most wonderful organs in the whole +body. It enables us to know what is going on at some distance from us, +and to enjoy many beautiful things which our sense of hearing and other +senses can tell us nothing about. It also enables us to read. Let us +learn how this wonderful organ is made. + +~9. The Eyeball.~--Looking at the eye, we see first a round part which +rolls in different directions. This is the _eyeball_. We see only the +front side of the eyeball as it fits into a hollow in the skull. Being +thus in a safe place, it is not likely to get hurt. + +[Illustration: THE EYE.] + +The eyeball is mostly filled with a clear substance very much like +jelly. It is so clear that the light can shine through it just as easily +as it can shine through water. + +~10. The Pupil.~--If you look sharply at the eyeball you will see a +small black hole just in the centre. This is a little window which lets +the light into the inside of the eyeball. We call this the _pupil_. Just +around the pupil is a colored ring which gives the eye its color. We say +a person has blue or brown or gray eyes according as this ring is blue +or brown or gray. This colored ring is a kind of curtain for the window +of the eye. + +~11.~ If you observe the pupil closely, you will see that it is +sometimes larger and sometimes smaller. If you look at the light the +pupil is small; if you turn away from the light the pupil grows larger +at once. This is because the curtain closes when in a bright light and +opens in the darkness. It does this of itself without our thinking about +it. In this way the eye is protected from too strong a light, which +would do it great harm. + +~12.~ If you look a little sidewise at the eyeball, you will see that +the curtain has something in front of it which is clear as glass. It is +about the shape of a watch crystal, only very much smaller. This is to +the eye what the glass is to the windows of a house. It closes the +opening in the front of the eyeball and yet lets the light shine in. + +~13. The White of the Eye.~--The white of the eye is a tough, firm +membrane which encloses the eyeball and keeps it in a round shape. + +~14. The Lens.~--Do you know what a lens is? Perhaps you do not know it +by this name, but you are familiar with the spectacles which people +sometimes wear to help their eyes. The glasses in the spectacle frames +are called lenses. Well, there is something in the eye almost exactly +like one of these lenses, only smaller. It is also called a _lens_. If +some one will get the eye of an ox for you, you can cut it open and find +this part. The lens is placed in the eyeball just behind the pupil. (See +picture.) + +[Illustration: THE INSIDE OF THE EYE.] + +~15. The Nerves of Sight.~--But a person might have an eyeball with all +the parts we have learned about and yet not be able to see. Can you tell +what more is needed? There must be a nerve. This nerve comes from some +little nerve cells in the brain and enters the eyeball at the back of +the eye; there it is spread out on the inside of the black lining of the +white of the eye. + +~16. The Eyelids.~--Now we know all that it is necessary for us to learn +about the eyeball, so let us notice some other parts about the eye. +First there are the eyelids. They are little folds of skin fringed with +hairs, which we can shut up so as to cover the eyeball and keep out the +light when we want to sleep or when we are in danger of getting dust or +smoke into the eye. The hairs placed along the edge of the lids help to +keep the dust out when the eyes are open. + +~17. The Eyebrows.~--The row of hairs placed above the eye is called the +eyebrow. Like the eyelids, the eyebrows catch some substances which +might fall into the eye, and they also serve to turn off the +perspiration and keep it out of the eyes. + +~18. The Tear Gland.~--Do you know where the tears come from? There is a +little gland snugly placed away in the socket of the eye just above the +eyeball, which makes tears in the same way that the salivary glands make +saliva. It is called the _tear gland_. The gland usually makes just +enough tears to keep the eye moist. There are times when it makes more +than enough, as when something gets into the eye, or when we suffer pain +or feel unhappy. Then the tears are carried off by means of a little +tube which runs down into the nose from the inner corner of the eye. +When the tears are formed so fast that they cannot all get away through +this tube, they pass over the edge of the lower eyelid and flow down the +cheek. + +~19. Muscles of the Eyes.~--By means of little muscles which are +fastened to the eyeball, we are able to turn the eye in almost every +direction. + +~20. How we See.~--Now we want to know how we see with the eye. This is +not very easy to understand, but we can learn something about it. Let us +make a little experiment. Here is a glass lens. If we hold it before a +window and place a piece of smooth white paper behind it, we can see a +picture of the houses and trees and fences, and other things +out-of-doors. The picture made by the lens looks exactly like the view +out-of-doors, except that it is upside down. This is one of the curious +things that a lens does. The lens of the eye acts just like a glass +lens. It makes a picture of everything we see, upon the ends of the +nerves of sight which are spread out at the back of the eyeball. The +nerves of sight tell their nerves in the brain about the picture, just +as the nerves of feeling tell their cells when they are touched with a +pin; and this is how we see. + +~21.~ Did you ever look through a spyglass or an opera-glass? If so, you +know you must make the tube longer or shorter according as you look at +things near by or far away. The eye also has to be changed a little +when we look from near to distant objects. Look out of the window at a +tree a long way off. Now place a lead pencil between the eyes and the +tree. You can scarcely see the pencil while you look sharply at the +tree, and if you look at the pencil you cannot see the tree distinctly. + +~22.~ There is a little muscle in the eye which makes the change needed +to enable us to see objects close by as well as those which are farther +away. When people grow old the little muscles cannot do this so well, +and hence old people have to put on glasses to see objects near by, as +in reading. Children should not try to wear old persons' glasses, as +this is likely to injure their eyes. + +~23. How to Keep the Eyes Healthy.~--(1.) Never continue the use of the +eyes at fine work, such as reading or fancy-work, after they have become +very tired. + +(2.) Do not try to read or to use the eyes with a poor light--in the +twilight, for instance, before the gas or lamps are lighted. + +(3.) In reading or studying, do not sit with the light from either a +lamp or a window shining directly upon the face. Have the light come +from behind and shine over the left shoulder if possible. + +(4.) Never expose the eyes to a sudden, bright light by looking at the +sun or at a lamp on first awaking in the morning, or by passing quickly +from a dark room into a lighted one. + +(5.) Do not read when lying down, or when riding on a street car or +railway train. + +(6.) If any object gets into the eye have it removed as soon as +possible. + +(7.) A great many persons hurt their eyes by using various kinds of +eye-washes. Never use anything of this kind unless told to do so by a +good physician. + +~24. How we Smell.~--If we wish to smell anything very strongly, we +sniff or suddenly draw the air up through the nose. We do this to bring +more air to the nerves of smell, which are placed at the upper part of +the inside of the nose. + +[Illustration: INSIDE OF THE NOSE.] + +~25.~ Smelling is a sort of feeling. The nerves of smell are so +sensitive that they can discover things in the air which we cannot taste +or see. An Indian uses his sense of smell to tell him whether things +are good to eat or not. He knows that things which have a pleasant smell +are likely to be good for him and not likely to make him sick. + +We do not make so much use of the sense of smell as do the savages and +many lower animals, and hence we are not able to smell so acutely. Many +persons lose the sense of smell altogether, from neglecting colds in the +head. + +~26. How we Taste.~--The tongue and the palate have very delicate nerves +by means of which we taste. We cannot taste with the whole of the +tongue. The very tip of the tongue has only nerves of touch or feeling. + +~27.~ The use of the sense of taste is to give us pleasure and to tell +us whether different substances are healthful or injurious. Things which +are poisonous and likely to make us sick almost always have an +unpleasant taste as well as an unpleasant odor. Things which have a +pleasant taste are usually harmless. + +~28. Bad Tastes.~--People sometimes learn to like things which have a +very unpleasant taste. Pepper, mustard, pepper-sauce, and other hot +sauces, alcohol, and tobacco are harmful substances of this sort. When +used freely they injure the sense of taste so that it cannot detect and +enjoy fine and delicate flavors. These substances, as we have elsewhere +learned, also do the stomach harm and injure the nerves and other parts +of the body. + +~29. The Sense of Touch.~--If you put your hand upon an object you can +tell whether it is hard or soft, smooth or rough, and can learn whether +it is round or square, or of some other shape. You are able to do this +by means of the nerves of touch, which are found in the skin in all +parts of the body. If you wished to know how an object feels, would you +touch it with the elbow, or the knee, or the cheek? You will say, No. +You would feel of it with the hand, and would touch it with the ends of +the fingers. You can feel objects better with the ends of the fingers +because there are more nerves of touch in the part of the skin covering +the ends of the fingers than in most other parts of the body. + +~30.~ The sense of touch is more delicate in the tip of the tongue than +in any other part. This is because it is necessary to use the sense of +touch in the tongue to assist the sense of taste in finding out whether +things are good to eat or not. The sense of touch is also very useful to +us in many other ways. We hardly know how useful it really is until we +are deprived of some of our other senses, as sight or hearing. In a +blind man the sense of touch often becomes surprisingly acute. + +~31. Effects of Alcohol and Tobacco on the Special Senses.~--All the +special senses--hearing, seeing, smelling, tasting, feeling--depend upon +the brain and nerves. Whatever does harm to the brain and nerves must +injure the special senses also. We have learned how alcohol and tobacco, +and all other narcotics and stimulants, injure and sometimes destroy the +brain cells and their nerve branches, and so we can understand that a +person who uses these poisonous substances will, by so doing, injure the +delicate organs with which he hears, sees, smells, etc. + +~32.~ Persons who use tobacco and strong drink sometimes become blind, +because these poisons injure the nerves of sight. The ears are +frequently injured by the use of tobacco. Smoking cigarettes and +snuff-taking destroy the sense of smell. The poison of the tobacco +paralyzes the nerves of taste so that they cannot detect flavors. +Tea-tasters and other persons who need to have a delicate sense of taste +do not use either alcohol or tobacco. + + +SUMMARY. + +1. We have five special senses--hearing, seeing, smelling, tasting, and +feeling. + +2. The ear is the organ of hearing, and has three parts, called the +external ear, the middle ear, and the inner ear. The inner ear contains +the nerve of hearing. + +3. The middle ear is separated from the external ear by the drum-head. +The drum-head is connected with the inner ear by a chain of bones. + +4. Sounds cause the drum-head to vibrate. The ear-bones convey the +vibration from the drum-head to the nerve of hearing. + +5. To keep the ear healthy we must avoid meddling with it or putting +things into it. + +6. The eye is the organ of sight. The chief parts of the eye are the +eyeball, the socket, and the eyelids. + +7. In the eyeball are the pupil, the lens, and the nerve of sight. + +8. The eyeball is moved in various directions by six small muscles. + +9. The eye is moistened by tears from the tear-gland. + +10. When we look at an object the lens of the eye makes a picture on the +nerve of sight, at the back part of the eyeball. + +11. To keep the eyes healthy we should be careful not to tax them long +at a time with fine work, or to use them in a poor light. + +12. The nerves of smell are placed in the upper part of the inside of +the nose. + +13. "Colds" often destroy the sense of smell. + +14. The nerves of taste are placed in the tongue and palate. + +15. Many things which we think we taste we really do not taste, but +smell or feel. + +16. Objects which have a pleasant taste are usually healthful, while +those which have a bad taste are usually harmful. + +17. Pepper, mustard, etc., as well as alcohol and tobacco, have an +unpleasant taste, and are not healthful. If we use them we shall injure +the nerves of taste as well as other parts of the body. + +18. We feel objects by means of the sense of touch. + +19. The sense of touch is most acute at the tip of the tongue and the +ends of the fingers. + + + + +CHAPTER XXVI. + +ALCOHOL. + + +~1.~ As we learned in the early part of our study of this subject, +alcohol is produced by _fermentation_. It is afterwards separated from +water and other substances by _distillation_. We will now learn a few +more things about alcohol. + +~2. Alcohol Burns.~--If alcohol is placed in a lamp, it will burn much +like kerosene oil. Indeed, it does not need a lamp to help it burn as +does oil. If a few drops of alcohol are placed upon a plate, it may be +lighted with a match, and will burn with a pale blue flame. Thus you see +that alcohol is a sort of burning fluid. + +~3.~ The vapor of alcohol will burn also, and under some circumstances +it will explode. On this account it is better not to try any experiments +with it unless some older person is close by to direct you, so that no +harm may be done. Alcohol is really a dangerous substance even though we +do not take it as a drink. + +~4. An Interesting Experiment.~--We have told you that all fermented +drinks contain alcohol. You will remember that wine, beer, ale, and +cider are fermented drinks. We know that these drinks contain alcohol +because the chemist can separate the alcohol from the water and other +substances, and thus learn just how much alcohol each contains. + +~5.~ If we should remove all the alcohol from wine, no one would care to +drink it. The same is true of beer and cider. It is very easy to remove +the alcohol by the simple process of heating. This is the way the +chemist separates it. The heat drives the alcohol off with the steam. If +the heating is continued long enough, all the alcohol will be driven +off. The Chinaman boils his wine before drinking it. Perhaps this is one +reason why Chinamen are so seldom found drunken. + +~6.~ By a simple experiment which your parents or your teacher can +perform for you, it can be readily proven that different fermented +drinks contain alcohol, and also that the alcohol may be driven off by +heat. Place a basin half full of water upon the stove where it will soon +boil. Put into a glass bottle enough beer or cider so that when the +bottle stands up in the basin the liquid in the bottle will be at about +the same height as the water in the basin. Now place in the neck of the +bottle a closely fitting cork in which there has been inserted a piece +of the stem of a clay pipe or a small glass tube. Place the bottle in +the basin. Watch carefully until the liquid in the bottle begins to +boil. Now apply a lighted match to the end of the pipe-stem or glass +tube. Perhaps you will observe nothing at first, but continue placing +the match to the pipe-stem, and pretty soon you will notice a little +blue flame burning at the end of the stem. It will go out often, but you +can light it again. This is proof that alcohol is escaping from the +liquid in the bottle. After the liquid has been boiling for some time, +the flame goes out, and cannot be re-lighted, because the alcohol has +been all driven off. + +[Illustration: Alcohol experiment.] + +~7. The Alcohol Breath.~--You have doubtless heard that a person who is +under the influence of liquor may be known by his breath. His breath +smells of alcohol. This is because his lungs are trying to remove the +alcohol from his blood as fast as possible, so as to prevent injury to +the blood corpuscles and the tissues of the body. It is the vapor of +alcohol mixed with his breath that causes the odor. + +~8.~ You may have heard that sometimes men take such quantities of +liquor that the breath becomes strong with the vapor of alcohol and +takes fire when a light is brought near the mouth. These stories are +probably not true, although it sometimes happens that persons become +diseased in such a way that the breath will take fire if it comes in +contact with a light. Alcohol may be a cause of this kind of disease. + +~9. Making Alcohol.~--It may be that some of our young readers would +like to find out for themselves that alcohol is really made by +fermentation. This may be done by an easy experiment. You know that +yeast will cause bread to "rise" or ferment. As we have elsewhere +learned, a little alcohol is formed in the fermentation of bread, but is +driven off by the heat of the oven in baking, so that we do not take any +of it into our stomachs when we eat the bread. If we place a little +baker's yeast in sweetened water, it will cause it to ferment and +produce alcohol. To make alcohol, all we have to do is to place a little +yeast and some sweetened water in a bottle and put it away in a warm +place for a few hours until it has had time to ferment. You will know +when fermentation has taken place by the great number of small bubbles +which appear. When the liquid has fermented, you may prove that alcohol +is present by means of the same experiment by which you found the +alcohol in cider or wine. (See page 160.) + +~10.~ Alcohol is made from the sweet juices of fruits by simply allowing +them to ferment. Wine, as you know, is fermented grape juice. Cider is +fermented apple juice. The strong alcoholic liquor obtained by +distilling wine, cider, or any kind of fermented fruit juice, is known +as brandy. + +~11. How Beer is Made.~--Beer is made from grain of some sort. The grain +is first moistened and kept in a warm place for a few days until it +begins to sprout. The young plant needs sugar for its food; and so while +the grain is sprouting, the starch in the grain is changed into sugar by +a curious kind of digestion. This, as you will remember, is the way in +which the saliva acts upon starch. So far no very great harm has been +done, only sprouted grain, though very sweet, is not so good to eat as +grain which has not sprouted. Nature intends the sugar to be used as +food for the little sproutlet; but the brewer wants it for another +purpose, and he stops the growth of the plant by drying the grain in a +hot room. + +~12.~ The next thing the brewer does is to grind the sprouted grain and +soak it in water. The water dissolves out the sugar. Next he adds yeast +to the sweet liquor and allows it to ferment, thus converting the sugar +into alcohol. Potatoes are sometimes treated in a similar way. + +~13.~ By distilling beer, a strong liquor known as whiskey is obtained. +Sometimes juniper berries are distilled with the beer. The liquor +obtained is then called gin. In the West Indies, on the great sugar +plantations, large quantities of liquor are made from the skimmings and +cleanings of the vessels in which the sweet juice of the sugar-cane is +boiled down. These refuse matters are mixed with water and fermented, +then distilled. This liquor is called rum. + +~14.~ Now you have learned enough about alcohol to know that it is not +produced by plants in the same way that food is, but that it is the +result of a sort of decay. In making alcohol, good food is destroyed and +made into a substance which is not fit for food, and which produces a +great amount of sickness and destroys many lives. Do you not think it a +pity that such great quantities of good corn and other grains should be +wasted in this way when they might be employed for a useful purpose? + +~15. The Alcohol Family.~--Scientists tell us that there are several +different kinds of alcohol. Naphtha is a strong-smelling liquid +sometimes used by painters to thin their paint and make it dry quickly. +It does not have the same odor as alcohol, but it looks and acts very +much like it. It will burn as alcohol does. It kills animals and plants. +It will make a person drunk if he takes a sufficient quantity of it. +Indeed, it is so like alcohol that it really is a kind of alcohol. + +~16.~ There are also other kinds of alcohol. Fusel-oil, a deadly poison, +is an alcohol. A very small amount of this alcohol will make a person +very drunk. Fusel-oil is found in bad whiskey. (All whiskey is bad, but +some kinds are worse than others.) This is why such whiskey makes men so +furiously drunk. It also causes speedy death in those who use it +frequently. There are still other kinds of alcohol, some of which are +even worse than fusel-oil. So you see this is a very bad family. + +~17.~ Like most other bad families, this alcohol family has many bad +relations. You have heard of carbolic acid, a powerful poison. This is +one of the relatives of the alcohol family. Creosote is another +poisonous substance closely related to alcohol. Ether and chloroform, by +which people are made insensible during surgical operations, are also +relatives of alcohol. They are, in fact, made from alcohol. These +substances, although really useful, are very poisonous and dangerous. Do +you not think it will be very wise and prudent for you to have nothing +to do with alcohol in any form, even wine, beer, or cider, since it +belongs to such a bad family and has so many bad relations? + +~18.~ Some persons think that they will suffer no harm if they take only +wine or beer, or perhaps hard cider. This is a great mistake. A person +may get drunk on any of these drinks if a sufficient amount be taken. +Besides, boys who use wine, beer, or cider, rarely fail to become fond +of stronger liquors. A great many men who have died drunkards began with +cider. Cider begins to ferment within a day or two after it is made, and +becomes stronger in alcohol all the time for many months. + +~19. "Bitters."~--There are other liquids not called "drinks" which +contain alcohol. "Bitters" usually contain more alcohol than is found in +ale or wine, and sometimes more than in the strongest whiskey. "Jamaica +ginger" is almost pure alcohol. Hence, it is often as harmful for a +person to use these medicines freely as to use alcoholic liquors in any +other form. + +~20.~ Alcoholic liquors of all kinds are often adulterated. That is, +they contain other poisons besides alcohol. In consequence of this, +they may become even more harmful than when pure; but this does not make +it safe to use even pure liquor. Alcohol is itself more harmful than the +other drugs usually added in adulteration. It is important that you +should know this, for many people think they will not suffer much harm +from the use of alcohol if they are careful to obtain pure liquors. + +~21. Some Experiments.~--How many of you remember what you have learned +in previous lessons about the poisonous effects of alcohol? Do people +ever die at once from its effects? Only a short time ago a man made a +bet that he could take five drinks of whiskey in five seconds. He +dropped dead when he had swallowed the fourth glass. No one ever +suffered such an effect from taking water or milk or any other good food +or drink. + +~22.~ A man once made an experiment by mistake. He was carrying some +alcohol across a lawn. He accidentally spilled some upon the grass. The +next day he found the grass as dead and brown as though it had been +scorched by fire. + +~23.~ Mr. Darwin, the great naturalist, once made a curious experiment. +He took a little plant with three healthy green leaves, and shut it up +under a glass jar where there was a tea-spoonful of alcohol. The +alcohol was in a dish by itself, so it did not touch the plant; but the +vapor of the alcohol mixed with the air in the jar so that the plant had +to breathe it. In less than half an hour he took the plant out. Its +leaves were faded and somewhat shrivelled. The next morning it appeared +to be dead. Do you suppose the odor of milk or meat, or of any good +food, would affect a plant like that? Animals shut up with alcohol die +in just the same way. + +~24. A Drunken Plant.~--How many of you remember about a curious plant +that catches flies? Do you remember its name? What does the Venus's +fly-trap do with the flies after it catches them? Do you say that it +eats them? Really this is what it does, for it dissolves and absorbs +them. In other words, it digests them. This is just what our stomachs do +to the food we eat. + +~25.~ A few years ago Mr. Darwin thought that he would see what effect +alcohol would have upon the digestion of a plant. So he put a +fly-catching plant in a jar with some alcohol for just five minutes. The +alcohol did not touch the plant, because the jar was only wet with the +alcohol on the inside. When he took the plant out, he found that it +could not catch flies, and that its digestion was spoiled so that it +could not even digest very tender bits of meat which were placed on its +leaves. The plant was drunk. + +~26.~ Mr. Darwin tried a great many experiments with various poisons, +and found that the plants were affected in much the same way by ether +and chloroform, and also by nicotine, the poisonous oil of tobacco. +Sugar, milk, and other foods had no such effect. This does not look much +as though alcohol would help digestion; does it? + +~27. Effects of Alcohol on Digestion.~--Dr. Roberts, a very eminent +English scientist, made many experiments, a few years ago, to ascertain +positively about the effect of alcohol upon digestion. He concluded that +alcohol, even in small doses, delays digestion. This is quite contrary +to the belief of very many people, who suppose that wine, cider, or +stronger liquors aid digestion. The use of alcohol in the form of beer +or other alcoholic drinks is often a cause of serious disease of the +stomach and other digestive organs. + +~28. Effects of Alcohol on Animal Heat.~--A large part of the food we +eat is used in keeping our bodies warm. Most of the starch, sugar, and +fat in our food serves the body as a sort of fuel. It is by this means +that the body is kept always at about the same temperature, which is +just a little less than one hundred degrees. This is why we need more +food in very cold weather than in very warm weather. + +~29.~ When a person takes alcohol, it is found that instead of being +made warmer by it, he is not so warm as before. He feels warmer, but if +his temperature be ascertained by means of a thermometer placed in his +mouth, it is found that he is really colder. The more alcohol a person +takes the colder he becomes. If alcohol were good food would we expect +this to be the case? It is probably true that the alcohol does make a +little heat, but at the same time it causes us to lose much more heat +than it makes. The outside of the body is not so warm as the inside. +This is because the warm blood in the blood-vessels of the skin is +cooled more rapidly than the blood in the interior of the body. The +effect of alcohol is to cause the blood-vessels of the outside of the +body to become much enlarged. This is why the face becomes flushed. A +larger amount of warm blood is brought from the inside of the body to +the outside, where it is cooled very rapidly; and thus the body loses +heat, instead of gaining it, under the influence of alcohol. This is not +true of any proper food substance. + +~30. Alcohol in the Polar Regions.~--Experience teaches the same thing +as science respecting the effect of alcohol. Captain Ross, Dr. Kane, +Captain Parry, Captain Hall, Lieutenant Greely, and many other famous +explorers who have spent long months amid the ice and snow and intense +cold of the countries near the North Pole, all say that alcohol does not +warm a man when he is cold, and does not keep him from getting cold. +Indeed, alcohol is considered so dangerous in these cold regions that no +Arctic explorer at the present time could be induced to use it. The +Hudson Bay Company do not allow the men who work for them to use any +kind of alcoholic liquors. Alcohol is a great deceiver, is it not? It +makes a man think he is warmer, when he is really colder. Many men are +frozen to death while drunk. + +~31. Alcohol in Hot Regions.~--Bruce, Livingstone, and Stanley, and all +great African travellers, condemn the use of alcohol in that hot country +as well as elsewhere. The Yuma Indians, who live in Arizona and New +Mexico, where the weather is sometimes much hotter than we ever know it +here, have made a law of their own against the use of liquor. If one of +the tribe becomes drunk, he is severely punished. This law they have +made because of the evil effects of liquor which they noticed among the +members of their tribe who used to become intoxicated. Do you not think +that a very wise thing for Indians to do? + +~32. Sunstroke.~--Do you know what sunstroke is? If you do not, your +parents or teacher will tell yow that persons exposed to the heat of the +sun on a hot summer day are sometimes overcome by it. They become weak, +giddy, or insensible, and not infrequently die. Scores of people are +sometimes stricken down in a single day in some of our large cities. It +may occur to you that if alcohol cools the body, it would be a good +thing for a person to take to prevent or relieve an attack of sunstroke. +On the contrary, it is found that those who use alcoholic drinks are +much more liable to sunstroke than others. This is on account of the +poisonous effects of the alcohol upon the nerves. No doctor would think +of giving alcohol in any form to a man suffering with sunstroke. + +~33. Effects of Alcohol upon the Tissues.~--Here are two interesting +experiments which your teacher or parents can make for you. + +_Experiment 1._ Place a piece of tender beefsteak in a saucer and cover +it with alcohol. Put it away over night. In the morning the beefsteak +will be found to be shrunken, dried, and almost as tough as a piece of +leather. This shows the effect of alcohol upon the tissues, which are +essentially like those of lower animals. + +_Experiment 2._ Break an egg into a half glassful of alcohol. Stir the +egg and alcohol together for a few minutes. Soon you will see that the +egg begins to harden and look just as though it had been boiled. + +~34.~ This is the effect of strong alcohol. The alcohol of alcoholic +drinks has water and other things mixed with it, so that it does not act +so quickly nor so severely as pure alcohol; but the effect is +essentially the same in character. It is partly in this way that the +brain, nerves, muscles, and other tissues of drinking men and women +become diseased. + +Eminent physicians tell us that a large share of the unfortunate persons +who are shut up in insane asylums are brought there by alcohol. Is it +not a dreadful thing that one's mind should be thus ruined by a useless +and harmful practice? + + +SUMMARY. + +1. Alcohol is produced by fermentation, and obtained by distillation. It +will burn like kerosene oil and other burning fluids. + +2. The vapor of alcohol will burn and will sometimes explode. + +3. Alcohol may be separated from beer and other fermented liquids by +boiling. + +4. Brandy is distilled from fermented fruit juice, whiskey and gin from +beer or fermented grains, rum from fermented molasses. + +5. Alcohol is the result of a sort of decay, and much good food is +destroyed in producing it. + +6. Besides ordinary alcohol, there are several other kinds. Naphtha and +fusel-oil are alcohols. + +7. All the members of the alcohol family are poisons; all will burn, and +all will intoxicate. The alcohol family have several bad relations, +among which are carbolic acid, ether, and chloroform. + +8. Cider, beer, and wine are harmful and dangerous as well as strong +liquors. "Bitters" often contain as much alcohol as the strongest +liquors, and sometimes more. + +9. Alcoholic liquors are sometimes adulterated, but they usually contain +no poison worse than alcohol. Pure alcohol is scarcely less dangerous +than that which is adulterated. + +10. Death sometimes occurs almost instantly from taking strong liquors. + +11. Alcohol will kill grass and other plants, if poured upon them or +about their roots. + +12. Mr. Darwin proved that the vapor of alcohol will kill plants; also +that plants become intoxicated by breathing the vapor of alcohol. + +13. Alcohol, even in small quantities, hinders digestion. + +14. Alcohol causes the body to lose heat so rapidly that it becomes +cooler instead of warmer. + +15. The danger of freezing to death when exposed to extreme cold is +greatly increased by taking alcohol. + +16. Stanley, and other African explorers, say that it is dangerous to +use alcoholic drinks in hot climates. + +17. In very hot weather, persons who use alcoholic drinks are more +subject to sunstroke than those who do not. + +18. Beefsteak soaked in alcohol becomes tough like leather. An egg +placed in alcohol is hardened as though it had been boiled. + +19. The effect of alcohol upon the brain, nerves, and other tissues of +the body is much the same as upon the beefsteak and the egg. + + + + +QUESTIONS FOR REVIEW. + + +CHAPTER I. THE HOUSE WE LIVE IN.--What is the body like? Does +the body resemble anything else besides a house? How is it like a +machine? Name the different parts of the body. What is anatomy? +physiology? hygiene? + +CHAPTER II. A GENERAL VIEW OF THE BODY.--What are the main +parts of the body? Name the different parts of the head; of the trunk; +of each arm; of each leg. What covers the body? + +CHAPTER III. THE INSIDE OF THE BODY.--What is the name of the +framework of the body? What is the skull? How is the back-bone formed? +Name the two cavities of the trunk. What does the chest contain? the +abdomen? + +CHAPTER IV. OUR FOODS.--Of what are our bodies made? What are +foods? Where do we get our foods? Name some animal foods; some vegetable +foods. What are poisons? + +CHAPTER V. UNHEALTHFUL FOODS.--Is the flesh of diseased animals +good for food? What can you say about unripe, stale, or mouldy foods? +What is adulteration of foods? What foods are most likely to be +adulterated? Are pepper, mustard, and other condiments proper foods? +What about tobacco? What is the effect of tobacco upon boys? + +CHAPTER VI. OUR DRINKS.--What is the only thing that will +satisfy thirst? Why do we need water? How does water sometimes become +impure? What is the effect of using impure water? What are the +properties of good water? Are tea and coffee good drinks? How is alcohol +made? Give familiar examples of fermentation. How are pure alcohol and +strong liquors made? Is alcohol a food? Why do you think it is a poison? +Do you think moderate drinking is healthful? + +CHAPTER VII. HOW WE DIGEST.--What is digestion? What is the +digestive tube? Name the different digestive organs. How many sets of +teeth has a person in his lifetime? How many teeth in each set? How many +pairs of salivary glands? What do they form? What is the gullet? +Describe the stomach. What is the gastric juice? How long is the +intestinal canal? What fluid is formed in the intestines? Where is the +liver found, and how large is it? What does the liver produce? What is +the gall-bladder, and what is its use? What does the liver do besides +producing bile? What and where is the pancreas? What does the pancreas +do? Where is the spleen? How many important organs of digestion are +there? How many digestive fluids? + +CHAPTER VIII. DIGESTION OF A MOUTHFUL OF BREAD.--Name the +different processes of digestion [mastication, action of saliva, +swallowing, action of stomach and gastric juice, action of bile, action +of pancreatic juice, action of intestines and intestinal juice, +absorption, liver digestion]. Describe the digestion of a mouthful of +bread. Where is the food taken after it has been absorbed? What are the +lacteals? What is the thoracic duct? + +CHAPTER IX. BAD HABITS IN EATING.--What is indigestion? Mention +some of the causes of indigestion. How does eating too fast cause +indigestion? Eating too much? too frequently? Irregularly? when tired? +How do tea and coffee impair digestion? Why is it harmful to use iced +foods and drinks? Why should we not eat pepper and other hot and +irritating things? How should the teeth be cared for? How does +tobacco-using affect the stomach? What dreadful disease is sometimes +caused by tobacco? How does alcohol affect the gastric juice? the +stomach? the liver? + +CHAPTER X. A DROP OF BLOOD.--What does the blood contain? How +many kinds of blood corpuscles are there? What work is done for the body +by each kind of corpuscles? + +CHAPTER XI. WHY THE HEART BEATS.--Where is the heart? Why does +the heart beat? How many chambers has the heart? What are the +blood-vessels? How many kinds of blood-vessels are there? Name them. +What is the difference between venous blood and arterial blood? What +change occurs in the blood in the lungs? What is the pulse? How much +work does the heart do every twenty-four hours? What are the lymphatics? +What do they contain, and what is their purpose? What are lymphatic +glands? + +CHAPTER XII. HOW TO KEEP THE HEART AND BLOOD HEALTHY.--Name +some things likely to injure the heart or the blood. What is the effect +of violent exercise? of bad air? of bad food? of loss of sleep? of +violent anger? What can you say about clothing? What is the effect of +alcohol upon the blood? the heart? the bodily heat? What is the effect +of tobacco upon the heart? the pulse? the blood? What is the effect of +tea and coffee upon the heart? What is a cold? In a case of bleeding +from a wound, how can you tell whether a vein or an artery is cut? How +would you stop the bleeding from an artery? from a vein? How would you +stop nose-bleed? + +CHAPTER XIII. WHY AND HOW WE BREATHE.--What happens to a +lighted candle if shut up in a small, close place? to a mouse? Why is +air so necessary for a burning candle and for animals? How is the heat +of our bodies produced? Name the principal organs of breathing. +Describe each. How do we use the lungs in breathing? How much air will a +man's lungs hold? How much air do we use with each breath? What +poisonous substance does the air which we breathe out contain? Will a +candle burn in air which has been breathed? What happens to animals +placed in such air? What change takes place in the blood as it passes +through the lungs? How do plants purify the air? + +CHAPTER XIV. HOW TO KEEP THE LUNGS HEALTHY.--What is the thing +most necessary to preserve life? Name some of the ways in which the +blood becomes impure. Why is bad-smelling air dangerous to health? What +are germs? Why are some diseases "catching"? Name some such diseases. +What should be done with a person who has a "catching" disease? What is +the effect of the breath upon the air? How much air is poisoned and made +unfit to breathe by each breath? How much air do we spoil every minute? +every hour? How much pure air does each person need every minute? every +hour? How do we get fresh air into our houses? Why are windows and doors +not good means of ventilating in cold weather? How should a room be +ventilated? How should we use the lungs in breathing? What about the +clothing in reference to the lungs? Why is it injurious to breathe +habitually through the mouth? What is the effect of alcohol upon the +lungs? What is the effect of tobacco-using upon the throat and nose? + +CHAPTER XV. THE SKIN AND WHAT IT DOES.--How many layers in the +skin? What is each called? To what is the color of the skin due? What +glands are found in the true skin? What are the nails and what is their +purpose? How does the hair grow? Name the different uses of the skin? + +CHAPTER XVI. HOW TO TAKE CARE OF THE SKIN.--What happened to +the little boy who was covered with gold leaf? Why did he die? What is +the effect of neglecting to keep the skin clean? What is the effect of +wearing too much clothing and living in rooms which are too warm? How +should the hair be cared for? the nails? What is the effect of alcohol, +tobacco, and other narcotics upon the skin? + +CHAPTER XVII. THE KIDNEYS AND THEIR WORK.--What is the work of +the kidneys? How may we keep these organs healthy? What is the effect of +alcohol upon the kidneys? + +CHAPTER XVIII. OUR BONES AND THEIR USES.--How many bones in the +body? What are the bones called when taken all together? Name the +principal parts of the skeleton. Name the bones of the trunk, of the +arms, of the legs. What are the uses of the bones? What is a joint? What +is cartilage? By what are the bones held together? Of what are the bones +largely composed? + +CHAPTER XIX. HOW TO KEEP THE BONES HEALTHY.--What sort of +bread is best for the bones? Why? If a child tries to walk too early why +are its legs likely to become crooked? What are the effects of sitting +or lying in bad positions? Of wearing tight or poorly-fitting clothing? +Of tight or high-heeled shoes? What injuries are likely to happen to the +bones and joints by accident or rough play? + +CHAPTER XX. THE MUSCLES AND HOW WE USE THEM.--How many muscles +in the body? Of what are the muscles composed? How are many of the +muscles connected to the bones? To what are all bodily movements due? +How do the muscles act? What causes the muscles to act? Do all muscles +act only when we will to have them act? + +CHAPTER XXI. HOW TO KEEP THE MUSCLES HEALTHY.--What makes the +right arm of the blacksmith stronger than the left one? How should +exercise be taken? Mention some things in relation to the use of the +muscles which we ought not to do, and state the reasons why. What is the +effect of alcohol upon the muscles? of tobacco? of tea and coffee? + +CHAPTER XXII. HOW WE FEEL AND THINK.--With what part of the +body do we think? How many brains does a man have? How is each brain +divided? Of what is the brain largely composed? Where do the nerves +begin? What is the spinal cord? Why does it cause pain to prick the +finger? How many kinds of nerves are there? (_Ans._ Two; nerves of +feeling and nerves of work.) Name some of the different kinds of nerves +of feeling? Name some of the different kinds of work controlled by the +nerves of work. Of what use to the body are the brain and nerves? How +does the brain use the nerves? Of what use is the large brain? What does +the little brain do? Of what use is the spinal cord? + +CHAPTER XXIII. HOW TO KEEP THE BRAIN AND NERVES +HEALTHY.--Mention some things which we need to do to keep the brain +and nerves healthy. Mention some things which we ought not to do. + +CHAPTER XXIV. BAD EFFECTS OF ALCOHOL UPON THE BRAIN AND +NERVES.--What is the effect of alcohol upon the brain and nerves? +Does alcohol produce real strength? Does it produce real warmth? Does +alcohol make people better or worse? What is the effect of tobacco upon +the brain and nerves? Does the use of tobacco lead to other evil habits? +What about the effect of opium and other narcotics? + +CHAPTER XXV. HOW WE HEAR, SEE, SMELL, TASTE, AND FEEL.--How +many senses have we? What is the ear? Name the three parts of the ear. +How do we hear? How should we treat the ear? + +Name the principal parts of the eye? What are found in the eyeball? How +is the eyeball moved in the socket? How is the eye moistened? Of what +use is the lens of the eye? Of what use is the pupil of the eye? How may +we preserve the eyesight? + +Where are the nerves of smell located? Of what use is the sense of +smell? + +Where are the nerves of taste found? How is the sense of taste sometimes +injured or lost? What do we detect with the sense of taste? Of what use +to us is the sense of taste? + +With what sense do we feel objects? In what parts of the body is this +sense most delicate? Upon what do all the special senses depend? Does +anything that injures the brain and nerves also injure the special +senses? What is the effect of alcohol and tobacco upon the sense of +sight? How is the hearing affected by tobacco-using? The sense of smell? +The sense of taste? + +CHAPTER XXVI. ALCOHOL.--How is alcohol produced? In what +respect is alcohol like kerosene oil? Is alcohol a dangerous thing even +if we do not drink it? How can you prove that there is alcohol in wine, +beer, cider, and other fermented drinks? Can you tell by the odor of his +breath when a person has been drinking? Why? Does the breath ever take +fire? May alcohol be a cause? From what is brandy made? How are whiskey, +gin, and rum made? Is alcohol a result of growth, like fruits and +grains, or of decay? Is there more than one kind of alcohol? Mention +some of the members of the alcohol family. In what ways are the members +of this family alike? Name some of the bad relations. Are cider and +beer, as well as whiskey, dangerous? Why? Mention some other things, +besides drinks, which contain alcohol. Are alcoholic drinks adulterated? +Is pure alcohol safe? Is instant death ever produced by alcohol? Will +alcohol kill plants? Describe Mr. Darwin's experiment which proved this. +Can plants be made drunk by alcohol? Describe the experiment which +proves this. What has Dr. Roberts proven concerning the influence of +alcohol upon digestion? How are our bodies kept warm? Explain how +alcohol makes the body cooler? Do Arctic explorers use alcohol? Why not? +Does the use of alcohol prevent sunstroke? What do Stanley and +Livingstone say about the use of alcohol in Africa? What is the effect +of using alcohol upon meat and eggs? What is the effect of alcohol upon +the brain and other tissues of the body? Does alcohol cause insanity and +other diseases of the brain and nerves? + + +FOOTNOTES: + +[A] More properly _Carbonic dioxid_. + +[B] For the sake of brevity and clearness the author has included under +the term "little brain" the _medulla oblongata_ as well as the +_cerebellum_. + + +THE END. + + + + +Aids to Field and Laboratory Work in Botany + +_Apgars' Plant Analysis._ By E.A. and A.C. APGAR. + +Cloth, small 4to, 124 pages 55 cents + +A book of blank schedules, adapted to Gray's Botanies, for pupils' use +in writing and preserving brief systematic descriptions of the plants +analyzed by them in field or class work. Space is allowed for +descriptions of about one hundred and twenty-four plants with an +alphabetical index. + +An analytical arrangement of botanical terms is provided, in which the +words defined are illustrated by small wood cuts, which show at a glance +the characteristics named in the definition. + +By using the Plant Analysis, pupils will become familiar with the +meaning of botanical terms, and will learn how to apply these terms in +botanical descriptions. + +_Apgar's Trees of the Northern United States_ + +Their Study, Description, and Determination. For the use of Schools and +Private Students. By AUSTIN C. APGAR. + +Cloth, 12mo, 224 pages. Copiously Illustrated $1.00 + +This work has been prepared as an accessory to the study of Botany, and +to assist and encourage teachers in introducing into their classes +instruction in Nature Study. The trees of our forests, lawns, yards, +orchards, streets, borders and parks afford a most favorable and +fruitful field for the purposes of such study. They are real objects of +nature, easily accessible, and of such a character as to admit of being +studied at all seasons and in all localities. Besides, the subject is +one of general and increasing interest, and one that can be taught +successfully by those who have had no regular scientific training. + + +_Copies of either of the above books will be sent, prepaid, to any +address on receipt of the price by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +STORER AND LINDSAY'S + +~Elementary Manual of Chemistry~ + +By F.H. STORER, S.B., A.M., and W.B. LINDSAY, A.B., B.S. + +Cloth, 12mo, 453 pages. Illustrated. Price, $1.20 + +This work is the lineal descendant of the "Manual of Inorganic +Chemistry" of Eliot and Storer, and the "Elementary Manual of Chemistry" +of Eliot, Storer and Nichols. It is in fact the last named book +thoroughly revised, rewritten and enlarged to represent the present +condition of chemical knowledge and to meet the demands of American +teachers for a class book on Chemistry, at once scientific in statement +and clear in method. + +The purpose of the book is to facilitate the study and teaching of +Chemistry by the experimental and inductive method. It presents the +leading facts and theories of the science in such simple and concise +manner that they can be readily understood and applied by the student. +The book is equally valuable in the class-room and the laboratory. The +instructor will find in it the essentials of chemical science developed +in easy and appropriate sequence, its facts and generalizations +expressed accurately and scientifically as well as clearly, forcibly and +elegantly. + + "It is safe to say that no text-book has exerted so wide an + influence on the study of chemistry in this country as this work, + originally written by Eliot and Storer. Its distinguished authors + were leaders in teaching Chemistry as a means of mental training in + general education, and in organizing and perfecting a system of + instructing students in large classes by the experimental method. + As revised and improved by Professor Nichols, it continued to give + the highest satisfaction in our best schools and colleges. After + the death of Professor Nichols, when it became necessary to revise + the work again, Professor Lindsay, of Dickinson College, was + selected to assist Dr. Storer in the work. The present edition has + been entirely rewritten by them, following throughout the same plan + and arrangement of the previous editions, which have been so highly + approved by a generation of scholars and teachers. + + "If a book, like an individual, has a history, certainly the record + of this one, covering a period of nearly thirty years, is of the + highest and most honorable character."--_From The American Journal + of Science._ + +_Copies of this book will be sent prepaid to any address, on receipt of +the price, by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +~Chemistry~ + +TEXT-BOOKS AND LABORATORY METHODS + + Storer and Lindsay's Elementary Manual of Chemistry + By F.H. STORER, A.M., S.B., and W.B. LINDSAY, Ph.D. + Cloth, 12mo, 453 pages $1.20 + A standard manual for secondary schools and colleges. + + Clarke's Elements of Chemistry + By F.W. CLARKE. 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DORMAN STEELE, Ph.D. Cloth, 12mo, 392 pages $1.00 + A popular text-book, in which the principles of the science are + presented in such an attractive manner as to awaken and fix the attention + of every pupil. + + Trowbridge's New Physics + By JOHN TROWBRIDGE, S.D. Cloth, 12mo, 387 pages $1.20 + A thoroughly modern work, intended as a class manual of Physics + for colleges and advanced preparatory schools. + + Hammel's Observation Blanks in Physics + By WILLIAM C.A. HAMMEL. + Flexible, quarto, 42 pages. Illustrated 30 cents + A pupil's laboratory manual and notebook for the first term's work. + Blanks are left in which the pupil writes his observations and the + principles illustrated. + + +_Copies of any of these books will be sent, prepaid, to any address on +receipt of the price by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +Laboratory Physics + +Hammel's Observation Blanks in Physics + +By WILLIAM C.A. HAMMEL, Professor of Physics in Maryland State +School, Boards, Quarto, 42 pages. Illustrated 30 cents + +These Observation Blanks are designed for use as a Pupil's Laboratory +Manual and Note Book for the first term's work in the study of Physics. +They combine in convenient form descriptions and illustrations of the +apparatus required for making experiments in Physics, with special +reference to the elements of Air, Liquids, and Heat; directions for +making the required apparatus from simple inexpensive materials, and for +performing the experiments, etc. The book is supplied with blanks for +making drawings of the apparatus and for the pupil to record what he has +observed and inferred concerning the experiment and the principle +illustrated. + +The experiments are carefully selected in the light of experience and +arranged in logical order. The treatment throughout is in accordance +with the best laboratory practice of the day. + +Hon. W.T. Harris, U.S. Commissioner of Education, says of these Blanks: + +"I have seen several attempts to assist the work of pupils engaged in +the study of Physics, but I have never seen anything which promises to +be of such practical assistance as Hammel's Observation Blanks." + + +_Specimen copies of the above book will be sent prepaid to any address, +on receipt of the price, by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +Burnet's Zooelogy + +FOR + +HIGH SCHOOLS AND ACADEMIES + +BY + + MARGARETTA BURNET + Teacher of Zooelogy, Woodward High School, Cincinnati, O. + +Cloth, 12mo, 216 pages. Illustrated. Price, 75 cents + +This new text-book on Zooelogy is intended for classes in High Schools, +Academies, and other Secondary Schools. While sufficiently elementary +for beginners in the study it is full and comprehensive enough for +students pursuing a regular course in the Natural Sciences. It has been +prepared by a practical teacher, and is the direct result of school-room +experience, field observation and laboratory practice. + +The design of the book is to give a good general knowledge of the +subject of Zooelogy, to cultivate an interest in nature study, and to +encourage the pupil to observe and to compare for himself and then to +arrange and classify his knowledge. Only typical or principal forms are +described, and in their description only such technical terms are used +as are necessary, and these are carefully defined. + +Each subject is fully illustrated, the illustrations being selected and +arranged to aid the pupil in understanding the structure of each form. + + +_Copies of Burnet's School Zooelogy will be sent prepaid to any address, +on receipt of the price, by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +Zooelogy and Natural History + +Burnet's School Zooelogy + +By MARGARETTA BURNET. Cloth, 12mo, 216 pages 75 cents + +A new text-book for high schools and academies, by a practical teacher; +sufficiently elementary for beginners and full enough for the usual +course in Natural History. + +Needham's Elementary Lessons in Zooelogy + +By JAMES G. NEEDHAM, M.S. Cloth, 12mo, 302 pages 90 cents + +An elementary text-book for high schools, academies, normal schools and +preparatory college classes. Special attention is given to the study by +scientific methods, laboratory practice, microscopic study and practical +zooetomy. + +Cooper's Animal Life + +By SARAH COOPER. Cloth, 12mo, 427 pages $1.25 + +An attractive book for young people. Admirably adapted for supplementary +readings in Natural History. + +Holders' Elementary Zooelogy + +By C.F. HOLDER, and J.B. HOLDER, M.D. + +Cloth, 12mo, 401 pages $1.20 + +A text-book for high school classes and other schools of secondary +grade. + +Hooker's Natural History + +By WORTHINGTON HOOKER, M.D. Cloth, 12mo, 394 pages 90 cents + +Designed either for the use of schools or for the general reader. + +Morse's First Book in Zooelogy + +By EDWARD S. MORSE, Ph.D. Boards, 12mo, 204 pages 87 cents + +For the first study of animal life. The examples presented are such as +are common and familiar. + +Nicholson's Text-Book of Zooelogy + +By H.A. NICHOLSON, M.D. Cloth, 12mo, 421 pages $1.38 + +Revised edition. Adapted for advanced grades of high schools or +academies and for first work in college classes. + +Steele's Popular Zooelogy + +By J. DORMAN STEELE, Ph.D., and J.W.P. JENKS. + +Cloth, 12mo, 369 pages $1.20 + +For academies, preparatory schools and general reading. This popular +work is marked by the same clearness of method and simplicity of +statement that characterize all Prof. Steele's text-books in the Natural +Sciences. + +Tenneys' Natural History of Animals + +By SANBORN TENNEY and ABBEY A. TENNEY. + +Revised Edition. Cloth, 12mo, 281 pages $1.20 + +This new edition has been entirely reset and thoroughly revised, the +recent changes in classification introduced, and the book in all +respects brought up to date. + +Treat's Home Studies in Nature + +By Mrs. MARY TREAT. Cloth, 12mo, 244 pages 90 cents + +An interesting and instructive addition to the works on Natural History. + + +_Copies of any of the above books will be sent prepaid to any address, +on receipt of the price, by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +Text-Books in Geology + +Dana's Geological Story Briefly Told + +By JAMES D. DANA. 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DANA. + +Cloth, 8vo, 1087 pages. 1575 illustrations $5.00 + +This great work was thoroughly revised and entirely rewritten under the +direct supervision of its author, just before his death. It is +recognized as a standard authority, and is used as a manual of +instruction in all higher institutions of learning. + +Le Conte's Compend of Geology + +By JOSEPH LE CONTE, LL.D. Cloth, 12mo, 399 pages $1.20 + +Designed for high schools, academies, and all secondary schools. + +Steele's Fourteen Weeks in Geology + +By J. DORMAN STEELE, Ph.D. Cloth, 12mo, 280 pages $1.00 + +A popular book for elementary classes and the general reader. + +Andrews's Elementary Geology + +By E.B. ANDREWS, LL.D. Cloth, 12mo, 283 pages $1.00 + +Adapted for elementary classes. Contains a special treatment of the +geology of the Mississippi Valley. + + +_Copies of any of the above books will be sent, prepaid, to any address +on receipt of the price by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +A New Astronomy + +BY + +DAVID P. TODD, M.A., Ph.D. + +Professor of Astronomy and Director of the Observatory, Amherst College. + +Cloth, 12mo, 480 pages. Illustrated Price, $1.30 + +This book is designed for classes pursuing the study in High Schools, +Academies, and Colleges. The author's long experience as a director in +astronomical observatories and in teaching the subject has given him +unusual qualifications and advantages for preparing an ideal text-book. + +The noteworthy feature which distinguishes this from other text-books on +Astronomy is the practical way in which the subjects treated are +enforced by laboratory experiments and methods. In this the author +follows the principle that Astronomy is preeminently a science of +observation and should be so taught. + +By placing more importance on the physical than on the mathematical +facts of Astronomy the author has made every page of the book deeply +interesting to the student and the general reader. The treatment of the +planets and other heavenly bodies and of the law of universal +gravitation is unusually full, clear, and illuminative. The marvelous +discoveries of Astronomy in recent years, and the latest advances in +methods of teaching the science, are all represented. + +The illustrations are an important feature of the book. Many of them are +so ingeniously devised that they explain at a glance what pages of mere +description could not make clear. + + +_Copies of Todd's New Astronomy will be sent, prepaid, to any address on +receipt of the price by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +A Laboratory Manual in Practical Botany + +For use in Secondary Schools and for Elementary Work in Colleges + +By CHARLES H. CLARK, A.M., D.Sc., + +Principal of Windsor Hall School, Waban, Mass. + +Cloth, 12mo, 272 pages. Illustrated 96 cents + +The course of botanical study outlined in this book is intended to give +the student a general view of the subject, and at the same time to lay a +foundation upon which more advanced studies may be built. The book is +primarily a laboratory manual and follows the method recommended by the +Committee of Ten and employed by the best teachers. So pursued, the +study of botany provides the means of developing habits of close and +accurate observation and of cultivating the reasoning powers that can +scarcely be claimed for any other subject taught in the schools. + +It provides a systematic outline of classification to serve as a guide +in laboratory work and in the practical study of the life histories of +plants, their modes of reproduction, manner of life, etc. The treatment +is suggestive and general to adapt it to the courses of study in +different schools, and to allow the teacher to follow his own ideas in +selecting the work of his class. + + +Clark's Laboratory Manual in Practical Botany _will be sent, prepaid, to +any address on receipt of the price by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +Important New Books + +Crockett's Plane and Spherical Trigonometry + +By C.W. CROCKETT, C.E., Professor of Mathematics and Astronomy +in Rensselaer Polytechnic Institute, Troy, New York. With Tables. Cloth, +8vo. 310 pages $1.25 + +The Same. Without Tables 1.00 + +Logarithmic and Trigonometric Tables (separate) 1.00 + +A clear analytic treatment of the elements of Plane and Spherical +Trigonometry and their practical applications to Surveying, Geodesy, and +Astronomy, with convenient and accurate "five place" tables for the use +of the student, engineer, and surveyor. Designed for High Schools, +Colleges, and Technical Institutions. + +Raymond's Plane Surveying + +By W.G. RAYMOND, C.E., Member American Society of Civil +Engineers, Professor of Geodesy, Road Engineering, and Topographical +Drawing in Rensselaer Polytechnic Institute. + +Cloth, 8vo. 485 pages. With Tables and Illustrations $3.00 + +A modern text-book for the study and practice of Land, Topographical, +Hydrographical, and Mine Surveying. Special attention is given to such +practical subjects as system in office work, to labor-saving devices, to +cooerdinate methods, and to the explanation of difficulties encountered +by young surveyors. The appendix contains a large number of original +problems, and a full set of tables for class and field work. + +Todd's New Astronomy + +By DAVID P. TODD, M.A., Ph.D., Professor of Astronomy and +Director of the Observatory, Amherst College. + +Cloth, 12mo. 500 pages. Illustrated $1.30 + +A new Astronomy designed for classes pursuing the study in High Schools, +Academies, and other Preparatory Schools. The treatment throughout is +simple, clear, scientific, and deeply interesting. The illustrations +include sketches from the author's laboratory and expeditions, and +numerous reproductions from astronomical photographs. + + +_Copies of the above books will be sent, prepaid, to any address on +receipt of the price by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . CHICAGO + + * * * * * + +Birds of the United States + +A Manual for the Identification of Species East of the Rocky Mountains + +By AUSTIN C. APGAR + +Author of "Trees of the Northern United States," etc. + +Cloth, 12mo, 415 pages, with numerous +illustrations. Price, $2.00 + +The object of this book is to encourage the study of Birds by making it +a pleasant and easy task. The treatment, while thoroughly scientific and +accurate, is interesting and popular in form and attractive to the +reader or student. It covers the following divisions and subjects: + +PART I. A general description of Birds and an explanation of +the technical terms used by ornithologists. + +PART II. Classification and description of each species with +Key. + +PART III. The study of Birds in the field, with Key for their +identification. + +PART IV. Preparation of Bird specimens. + +The descriptions of the several species have been prepared with great +care and present several advantages over those in other books. They are +short and so expressed that they may be recalled readily while looking +at the bird. They are thus especially adapted for field use. The +illustrations were drawn especially for this work. Their number, +scientific accuracy, and careful execution add much to the value and +interest of the book. The general Key to Land and Water Birds and a very +full index make the book convenient and serviceable both for the study +and for field work. + + +_Apgar's Birds of the United States will be sent, prepaid, to any +address on receipt of the price by the Publishers:_ + +American Book Company + + NEW YORK . CINCINNATI . 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