[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, SOCIÉTÉ D'HYGIÈNE 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 authorhas aimed to accomplish in the preparation of the work have been:

1. To present as fully as possible and proper in a work of thischaracter a statement of the laws of healthful living, giving suchspecial prominence to the subject of stimulants and narcotics as itsrecognized importance and the recent laws relating to the study of thisbranch of hygiene demand. 

2. To present in a simple manner such anatomical and physiological factsas shall give the child a good fundamental knowledge of the structureand functions of the human body. 

3. To present each topic in such clear and simple language as to enablethe pupil to comprehend the subject-matter with little aid from theteacher; and to observe in the manner of presentation the principle thatthe things to be studied should be placed before the mind of the childbefore they are named. A natural and logical order has been observed inthe sequence of topics. Technical terms have been used very sparingly, and only in their natural order, and are then fully explained and theirpronunciation indicated, so that it is not thought necessary to append aglossary. 

4. To present the subjects of Physiology and Hygiene in the light ofthe most recent authentic researches in these branches of science, andto avoid the numerous errors which have for many years been current inthe school literature of these subjects. 

There is no subject in the presentation of which object-teaching may beemployed with greater facility and profit than in teaching Physiology, and none which may be more advantageously impressed upon the student'smind by means of simple experimentation than the subject of Hygiene. Every teacher who uses this book is urgently requested to supplementeach lesson by the use of object-teaching or experiments. A great numberof simple experiments illustrative of both Physiology and Hygiene may bereadily arranged. Many little experiments are suggested in the text, which should invariably be made before the class, each member of whichshould also be encouraged to repeat them at home. 

It is also most desirable that the teacher should have the aid ofsuitable charts and models. 

In conclusion, the author would acknowledge his indebtedness for a largenumber of useful suggestions and criticisms to several medical friendsand experienced teachers, and especially to Prof. Henry Sewall, of theUniversity of Michigan, for criticisms of the portions of the workrelating 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 BOOKOFPHYSIOLOGY AND HYGIENE. 

CHAPTER I. 

THE HOUSE WE LIVE IN. 

~1. Object of this Book. ~--The object of this book is to tell the littleboys and girls who read it about a wonderful house. You have all seensome 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 somefriend who does. If so, you know that the inside of the house is evenmore beautiful than the outside. There are elegant chairs and sofas inthe rooms, rich carpets and rugs on the floors, fine mirrors andbeautiful pictures upon the walls--everything one could wish to have ina 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 whichis far more wonderful and more curious than the grandest palace everbuilt. It is not a very large house. It has just room enough in it forone person. This house, which belongs to each one of us, is called thebody. 

~4. What is a Machine?~--Do you know what a machine is? Men makemachines to help them work and to do many useful things. A wheelbarrowor a wagon is a machine to carry loads. A sewing-machine helps to makegarments for us to wear. Clocks and watches are machines for keepingtime. 

~5. A Machine has Different Parts. ~--A wheelbarrow has a box in which tocarry things, two handles to hold by, and a wheel for rolling it along. Some machines, like wheelbarrows and wagons, have but few parts, and itis very easy for us to learn how they work. But there are othermachines, like watches and sewing-machines, which have many differentparts, and it is more difficult to learn all about them and what theydo. 

~6. The Body is Like a Machine. ~--In some ways the body is more like amachine than like a house. It has many different parts which are madeto do a great many different kinds of work. We see with our eyes, hearwith our ears, walk with our legs and feet, and do a great many thingswith our hands. If you have ever seen the inside of a watch or a clockyou know how many curious little wheels it has. And yet a watch or aclock can do but one thing, and that is to tell us the time of day. Thebody has a great many more parts than a watch has, and for this reasonthe body can do many more things than a watch can do. It is moredifficult, 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 muststudy all its different parts and learn how they are put together, andwhat each part does. Then, if we want the machine to work well and tolast a long time, we must know how to use it and how to take proper careof it. Do you think your watch would keep the time well if you shouldneglect 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, howthey are put together, and how they work. Then we must learn how to takeproper care of the body, so that its parts will be able to work welland last a long time. 

~9. ~ Each part of the body which is made to do some special kind of workis called an _organ_. The eye, the ear, the nose, a hand, an arm, anypart of the body that does something, is an organ. 

~10. ~ The study of the various parts of the body and how they are puttogether is _anatomy_ (a-nat´-o-my). The study of what each part of thebody does is _physiology_ (phys-i-ol´-o-gy). The study of how to takecare 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 thingsin 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 itwell and useful, just as we would take good care of a machine to keep itfrom wearing out too soon. 

4. The body has many different parts, called organs, each of which hassome particular work to do. 

5. In learning about the body, we have to study anatomy, physiology, andhygiene. 

6. The study of the various parts of the body, how they are formed andjoined 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? Thetrunk, 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. Thebranches of a tree we call limbs, and so we speak of the arms and legsas _limbs_. We sometimes call the arms the _upper extremities_, and thelegs the _lower extremities_. At the top of the trunk is the head. 

~2. Names of the Parts. ~--Now let us look more closely at thesedifferent parts. As we speak the name of each part, let each one touchthat part of himself which is named. We will begin with the head. Thechief 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 assoft and smooth as the finest silk. It is the _skin_. What is it thatgrows from the skin on the head? and what at the ends of the fingers andthe toes? We shall learn more about the skin, the hair, and the nails inanother lesson. 

~7. ~ The body has two sides, the right side and the left side, which arealike. 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, whichare 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. Theneck joins the head and trunk. 

4. Each arm has a shoulder, upper-arm, fore-arm, wrist, and hand. Thefingers belong to the hand. 

5. Each leg has a hip, thigh, lower leg, ankle, and foot. The toesbelong 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 thebody, just as if we had looked at the case of a watch, and of course wehave found out very little about its many wonderful parts. Very likelyyou want to ask a great many questions, such as, How does the inside ofthe body look? What is in the skull? What is in the chest? What is inthe abdomen? Why do we eat and drink? Why do we become hungry andthirsty? What makes us tired and sleepy? How do we keep warm? Why do webreathe? 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 weremember, think, and reason? All these, and a great many moreinteresting 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 howwonderfully we are made. We cannot all see the inside of the body, andit is not necessary that we should do so. Many learned men have spenttheir whole lives in seeking to find out all about our bodies and thebodies of various animals. 

~3. The Bones. ~--If you take hold of your arm, it seems soft on theoutside; 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 youwish, you can easily get one of the bones of an animal at the butcher'sshop, or you may find one in the fields. 

~4. The Skeleton. ~--All the bones of an animal, when placed properlytogether, 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 allthe parts. 

~5. The Skull. ~--The bony part of the head is called the _skull_. In theskull is a hollow place or chamber. You know that a rich man often has astrong room or box in his fine house, in which to keep his gold andother valuable things. The chamber in the skull is the strong-room ofthe body. It has strong, tough walls of bone, and contains the _brain_. The brain is the most important, and also the most tender and delicateorgan in the whole body. This is why it is so carefully guarded frominjury. 

~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 aboveanother. Each bone has a hole through it, about as large as one of yourfingers. A large branch from the brain, called the _spinal cord_, runsdown through the middle of the backbone, so that the separate bones lookas 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. Itswalls are formed partly by the backbone and the ribs and partly byflesh. A fleshy wall divides the hollow of the trunk into two parts, anupper chamber called the _chest_, and a lower called the _abdomen_. 

~8. The Lungs and Heart. ~--The chest contains a pair of organs calledthe _lungs_, with which we breathe. It also contains something which wecan feel beating at the left side. This is the _heart_. The heart liesbetween the two lungs, and a little to the left side. 

~9. The Stomach and Liver. ~--In the abdomen are some very wonderfulorgans that do different kinds of work for the body. Among them are the_stomach_, the _bowels_, and the _liver_. There are, also, other organswhose names we shall learn when we come to study them. 

~10. Care of the Body. ~--We have only begun to study the beautifulhouse in which we live, and yet have we not learned enough to show ushow great and wise is the Creator who made us and all the wonderfulmachinery within our bodies? If some one should give you a beautifulpresent, would you treat it carelessly and spoil it, or would you takegood care of it and keep it nice as long as possible? Ought we not totake such care of our bodies as to keep them in that perfect andbeautiful 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 iscalled a bone. 

3. The bones are covered by the flesh. 

4. The bones of the head form the skull, which is hollow and containsthe brain. 

5. A row of bones arranged in the back, one above another, forms thebackbone. The backbone has a canal running through it lengthwise, inwhich lies the spinal cord. 

6. The trunk is hollow, and has two chambers, one called the cavity ofthe 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 veryimportant organs. 

9. Is it not our duty to take good care of our bodies as we would ofsome nice present from a friend?

CHAPTER IV. 

OUR FOODS. 

~1. ~ We all know very well that if we do not eat we shall rapidly losein weight, and become very weak and feeble. Did you ever think how muchone 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. Howmuch does he eat in a year? There are three hundred and sixty-five daysin a year; 365 multiplied by 2 equals 730. So a boy eats a good manytimes his own weight in a year. How much would a person eat in fiftyyears?

~2. ~ Our bodies are composed of what we eat. If we eat bad food, ourbodies will be made out of poor material, and will not be able to dotheir work well. So you see how important it is to learn something aboutour foods. We ought to know what things are good for us to eat, and whatwill do us harm. 

~3. Foods and Poisons. ~--Foods are those substances which nourish thebody and keep it in good working order. 

~4. ~ Our foods are obtained from both animals and plants. All foodreally comes from plants, however, since those animals which wesometimes use as food themselves live upon the vegetables which theyeat. For example, the ox and the cow eat grass and furnish us beef andmilk. Chickens eat corn and other grains, and supply us with eggs. 

~5. ~ The principal animal foods are milk, cheese, eggs, and thedifferent 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, andvarious kinds of nuts. Perhaps you know of some other kinds of fruitsbesides those mentioned. Your teacher will tell you that tomatoes, watermelons, and pumpkins are really fruits, though they are notgenerally so called. 

~7. ~ The seeds of grass-like plants are known as _grains_, of which wehave wheat, rye, barley, corn, and rice. There are a few seeds that growin 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 makeus sick or otherwise do us harm. These are called _poisons_. Only suchfood 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 knownas narcotics and stimulants, which, from their effects upon the body, may be classed as poisons. Tobacco, opium, alcohol, and chloral areincluded in this class. Death has often been caused by taking smallquantities of any of these poisonous drugs. We shall learn more of theeffects 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 plantfoods--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. Somepeople do not stop to think whether what they eat is good for them orlikely to do them harm. Sometimes, without knowing it, we eat thingswhich are harmful to us. Do you not think that we should try to learnwhat is good to eat and what is not good, and then be very careful notto 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 sometimesdiseased. Animals and vegetables that are diseased are not good forfood. Dishonest men, however, sometimes sell them to those who do notknow that they are unfit to be eaten. 

~3. ~ Pork, the flesh of the hog, is more likely to be diseased than anyother kind of animal food. 

~4. ~ Beef and mutton may be diseased also. Sheep and cattle aresometimes sick of diseases very much like those which human beingshave. Meat which is pale, yellowish, or of a dark red color, isunhealthful, and should not be eaten. Meat should never be eaten raw. Itshould always be well cooked. 

~5. Unripe Foods. ~--Most vegetable foods are unfit to be eaten whengreen or unripe, especially if uncooked. Sometimes persons are made verysick indeed by eating such articles as green apples or unripe peaches. 

~6. Stale or Decayed Foods. ~--Food which has been allowed to stand untilit is spoiled, or has become _stale_, _musty_, or _mouldy_, such asmouldy bread or fruit, or tainted meat, is unfit to be eaten, and isoften a cause of very severe sickness. Canned fish or other meats spoilvery quickly after the cans are opened, and should be eaten the sameday. 

~7. Adulterated Foods. ~--Many of our foods are sometimes spoiled orinjured by persons who put into them cheap substances which are harmfulto health. They do this so as to make more money in selling them. Thisis called _adulteration_. The foods which are most likely to be injuredby adulteration are milk, sugar, and butter. 

~8. ~ Milk is most often adulterated by adding water, though sometimesother things are added. Sometimes the water is not pure, and people aremade sick and die. The adulteration of milk or any other food is a verywicked practice. 

~9. ~ Butter is sometimes made almost wholly from lard or tallow. This iscalled _oleomargarine_ or _butterine_. If the lard or tallow is fromdiseased animals, the false butter made from it may cause disease. 

~10. ~ A great deal of the sugar and syrups which we buy is made fromcorn by a curious process, which changes the starch of the corn intosugar. Sugar which has been made in this way is not so sweet as canesugar, and is not healthful. 

~11. Condiments or Seasonings. ~--These are substances which are added toour food for the purpose of giving to it special flavors. Condiments arenot foods, because they do not nourish the body in any way, and are notnecessary 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 alittle time will raise a blister. If we happen to get a little pepper inthe eye, it makes it smart and become very red and inflamed. When wetake 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 enjoyeating them. Condiments are likely to do us great harm, and hence it isfar better not to use them. 

~14. Tobacco. ~--Most of you know that tobacco is obtained from a plantwhich has long, broad leaves. These leaves are dried and then rolled upinto cigars, ground into snuff, or prepared for chewing. 

[Illustration: Tobacco-Plant. ]

~15. ~ Tobacco has a smarting, sickening taste. Do you think it would begood to eat? Why not?

~16. ~ You know that tobacco makes people sick when they first begin touse 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. Aboy once gave a piece of tobacco to a monkey, which swallowed it notknowing what a bad thing it was. The monkey soon became sick and died. 

~18. ~ Many learned doctors have noticed the effects which come fromusing tobacco, and they all say it does great harm to boys, that itmakes them puny and weak, and prevents their growing up into strong anduseful men. If tobacco is not good for boys, do you think it can be goodfor men? Certainly you will say, No. 

SUMMARY. 

1. Both animals and plants are sometimes diseased. Flesh obtained fromsick or diseased animals is unfit for food. 

2. Unripe, stale, and mouldy foods are unfit to be eaten and likely tocause severe illness. 

3. Foods are sometimes spoiled by having things mixed with them whichare 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 afood, 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 willsatisfy 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, itwould become dry in a few hours, as the water would pass off into theair. Our bodies are losing water all the time, and we need to drink tokeep ourselves from drying up. 

~3. ~ Water is also very necessary for other purposes. It softens ourfood so that we can chew and swallow it, and helps to carry it around inthe body after it has been digested, in a way about which we shall learnin future lessons. 

~4. ~ Still another use for water is to dissolve and wash out of ourbodies, through the sweat of the skin, and in other ways, the waste andworn-out particles which are no longer of any use. 

~5. Impure Water. ~--Most waters have more or less substances dissolvedin them. Water which has much lime in it is called hard water. Suchwater 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-watersometimes contains substances which soak into wells from vaults orcesspools. Slops which are poured upon the ground soak down out ofsight; but the foul substances which they contain are not destroyed. They remain in the soil, and when the rains come, they are washed downinto the well if it is near by. You can see some of the things found inbad water in the illustration given on opposite page. 

~6. ~ It is best not to drink iced water when the body is heated, orduring meals. If it is necessary to drink very cold water, the badeffects 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 theyreally have little or no value as foods. Both tea and coffee contain apoison which, when separated in a pure form, is so deadly that a verysmall quantity is enough to kill a cat or a dog. This poison often doesmuch harm to those who drink tea or coffee very strong for any greatlength 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, ifwe light it. It is so clear and colorless that it looks like water. TheIndians call it "fire-water. " Alcohol differs very much from foods. Itis not produced from plants, as fruits and grains are; neither is itsupplied by Nature ready for our use, as are air and water. 

~9. Fermentation. ~--When a baker makes bread he puts some yeast in thedough to make it "rise, " so the bread will be light. The yeast destroyssome of the sugar and starch in the flour and changes it into alcoholand a gas. The gas bubbles up through the dough, and this is what makesthe bread light. This is called _fermentation_ (fer-men-ta´-tion). Thelittle alcohol which is formed in the bread does no harm, because it isall driven off by the heat when the bread is baked. 

[Illustration: FERMENTATION. ]

~10. ~ Any moist substance or liquid which contains sugar will ferment ifyeast is added to it, or if it is kept in a warm place. You know thatcanned fruit sometimes spoils. This is because it ferments. Fermentationis a sort of decay. When the juice of grapes, apples, or other fruit isallowed to stand in a warm place it "works, " or ferments, and thusproduces alcohol. Wine is fermented grape-juice; hard cider is fermentedapple-juice. 

~11. ~ Beer, ale, and similar drinks are made from grains. The grain isfirst moistened and allowed to sprout. In sprouting, the starch of thegrain is changed to sugar. The grain is next dried and ground, and isthen boiled with water. The water dissolves the sugar. The sweet liquidthus obtained is separated from the grain, and yeast is added to it. This causes it to ferment, which changes the sugar to alcohol. Thus wesee that the grain does not contain alcohol in the first place, but thatit is produced by fermentation. 

~12. ~ All fermented liquids contain more or less alcohol, mixed withwater and a good many other things. Rum, brandy, gin, whiskey, and purealcohol 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 littleexperiment. When a tea-pot is boiling on the stove and the steam iscoming out at the nozzle, hold up to the nozzle a common drinking-glassfilled with iced water, first taking care to wipe the outside of theglass perfectly dry. Little drops of water will soon gather upon theside of the glass. If you touch these to the tongue you will observethat they taste of the tea. It is because a little of the tea hasescaped with the steam and condensed upon the glass. This isdistillation. 

~14. ~ If the tea-pot had contained wine, or beer, or hard cider, thedistilled water would have contained alcohol instead of tea. Bydistilling the liquid several times the alcohol may be obtained almostpure. 

~15. Alcohol kills Animals and Plants. ~--Strong alcohol has a deadlyeffect upon all living things. Once a man gave a dog a fewtablespoonfuls of alcohol, and in a little while the dog was dead. Ifyou 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 jarof water and then poured in a few teaspoonfuls of alcohol. The minnowstried very hard to get out, but they could not, and in a little whilethey were all dead, poisoned by the alcohol. A Frenchman once gavealcohol to some pigs with their food. They soon became sick and died. 

~17. Alcohol not a Food. ~--There are some people who imagine thatalcohol is good for food because it is made from fruits and grains whichare good for food. This is a serious mistake. A person can live on thefruits or grains from which alcohol is made, but no one would attemptto 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 offood. 

~18. ~ We should remember, also, that people do not take alcohol as afood, but for certain effects which it produces, which are not those ofa food, but of a poison. 

~19. ~ Many people who would not drink strong or distilled liquors, thinkthat they will suffer no harm if they use only wine, beer, or cider. This is a great mistake. These liquids contain alcohol, as do allfermented drinks. A person will become drunk or intoxicated by drinkingwine, beer, or cider--only a larger quantity is required to produce thesame effect as rum or whiskey. 

~20. ~ Another very serious thing to be thought of is that if a personforms the habit of drinking wine, cider, or other fermented drinks, hebecomes so fond of the _effect they produce_ that he soon wants somestronger drink, and thus he is led to use whiskey or other strongliquors. On this account it is not safe to use any kind of alcoholicdrinks, either fermented or distilled. The only safe plan is to avoidthe use of every sort of stimulating or intoxicating drinks. 

~21. ~ It has been found by observation that those persons who useintoxicating 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 andother strong liquors, but also of those who use fermented drinks, aswine and beer. Beer drinkers are much more likely to suffer from diseasethan those who are strictly temperate. It is often noticed by physiciansthat when a beer-drinker becomes sick or meets with an accident, he doesnot recover so readily as one who uses no kind of alcoholic drinks. 

~23. ~ Alcoholic drinks not only make people unhealthy and shorten theirlives, but they are also the cause of much poverty and crime and anuntold 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. Wealso 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 tochildren, 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 andshortens life. 

CHAPTER VII. 

HOW WE DIGEST. 

~1. ~ Did you ever see a Venus's fly-trap? This curious plant grows inNorth Carolina. It is called a fly-trap because it has on each of itsleaves 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 theleaf, the trap shuts up at once, and the poor fly is caught and cannotget away. The harder it tries to escape, the more tightly the trapcloses 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 strangeplant, which seems to act so much like an animal. If we open the leafafter a few days, it will be found that the fly has almost entirelydisappeared. The fly has not escaped, but it has been dissolved by afluid formed inside of the trap, and the plant has absorbed a portion ofthe fly. In fact, it has really eaten it. The process by which food isdissolved and changed so that it can be absorbed and may nourish thebody, 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 itsfood, and as a stomach to digest it. The arrangement by which our foodis digested is much less simple than this. Let us study the differentparts by which this wonderful work is done. 

[Illustration: THE DIGESTIVE TUBE. ]

~4. The Digestive Tube. ~--The most important part of the work ofdigesting 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 littlespace. 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 calledthe _mouth_. The lips form the front part and the cheeks the sides. Atthe back part are three openings. One, the upper, leads into the nose. There are two lower openings. One of these leads into the stomach, andthe other leads to the lungs. The back part of the mouth joins the twotubes which lead from the mouth to the lungs and the stomach, and iscalled 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 smallchildren, are called _temporary_ or _milk teeth_. We lose these teethas the jaws get larger and the second or _permanent_ teeth take theirplace. There are twenty teeth in the first set, and thirty-two in thesecond. 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). Itis this fluid which moistens the mouth at all times. When we eat ortaste something which we like, the salivary glands make so much salivathat we sometimes say the mouth waters. One pair of the salivary glandsis at the back part of the lower jaw, in front of the ears. The othertwo pairs of glands are placed at the under side of the mouth. Thesaliva produced by the salivary glands is sent into the mouth throughlittle 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 digestivetube becomes enlarged, and has a shape somewhat like a pear. This is the_stomach_. In a full-grown person the stomach is sufficiently large tohold about three pints. At each end of the stomach is a narrow openingso arranged that it can be opened or tightly closed, as may benecessary. The upper opening allows the food to pass into the stomach, the lower one allows it to pass out into the intestines. This opening iscalled the _pylorus_ (py-lo´-rus), or gate-keeper, because it closes soas 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 littlepocket-like glands, in which a fluid called the _gastric juice_ isformed. This fluid is one of the most important of all the fluids formedin the digestive canal. 

[Illustration: GASTRIC GLAND. ]

~12. The Intestine~(in-tes´-tine). --At the lower end of the stomachthe digestive canal becomes narrow again. This narrow portion, calledthe _intestine_, is about twenty-five feet long in a grown person. Thelast few feet of the intestine is larger than the rest, and is calledthe _colon_. This long tube is coiled up and snugly packed away in thecavity of the abdomen. In the membrane lining the intestines are to befound little glands, which make a fluid called _intestinal juice_. 

~13. The Liver. ~--Close up under the ribs, on the right side of thebody, is a large chocolate-colored organ, called the _liver_. The liveris about half as large as the head, and is shaped so as to fit snuglyinto its corner of the abdomen. The chief business of the liver is tomake a fluid called _bile_, which is very necessary for the digestion ofour food. 

~14. ~ The bile is a bitter fluid of a golden-brown color. It is carriedto the intestine by means of a little tube or duct, which enters thesmall intestine a few inches below the stomach. When the bile is madefaster than it is needed for immediate use, it is stored up in a littlepear-shaped sac called the _gall-bladder_, which hangs from the underside of the liver. 

~15. ~ The liver is a very wonderful organ, and does many useful thingsbesides making bile. It aids in various ways in digesting the food, andhelps to keep the blood pure by removing from it harmful substanceswhich are formed within the body. 

~16. The Pancreas~(pan´-cre-as). --The _pancreas_ is another large andvery important gland which is found close to the stomach, lying justbehind it in the abdominal cavity. The pancreas forms a fluid called the_pancreatic juice_, which enters the small intestine at nearly the sameplace 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 ofdigestion, but it is so closely connected with the digestive organs thatwe need to know about it. 

~18. ~ Please note that there are five important organs of digestion. Themouth, 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 beabsorbed 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 glandsconnected 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 amuscle, 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 theintestinal juice. 

10. The liver lies under the ribs of the right side. It is about half aslarge as the head. It makes bile. 

11. When not needed for immediate use, the bile is stored up in a saccalled the gall-bladder. 

12. The pancreas is a gland which lies just back of the stomach. Itmakes 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, intestinaljuice, 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 canwatch 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 theother, and to keep the food between the teeth. 

~3. Mouth Digestion. ~--While the bread is being chewed, the saliva ismixed with it and acts upon it. The saliva moistens and softens the foodso that it can be easily swallowed and readily acted upon by the otherdigestive juices. You have noticed that if you chew a bit of hard breada few minutes it becomes sweet. This is because the saliva changes someof the starch of the food into sugar. 

~4. ~ After we have chewed the food, we swallow it, and it passes downthrough the oesophagus into the stomach. 

~5. Stomach Digestion. ~--As soon as the morsel of food enters thestomach, the gastric juice begins to flow out of the little glands inwhich it is formed. This mingles with the food and digests anotherportion 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 isdone to mix the gastric juice with the food. 

~6. ~ After an hour or two the stomach squeezes the food so hard that alittle of it, which has been digested by the gastric juice and thesaliva, escapes through the lower opening, the pylorus, of which we havealready learned. As the action of the stomach continues, more of thedigested food escapes, until all that has been properly acted upon haspassed out. 

~7. Intestinal Digestion. ~--We sometimes eat butter with bread, or takesome other form of fat in our food. This is not acted upon by the salivaor the gastric juice. When food passes out of the stomach into the smallintestine, a large quantity of bile is at once poured upon it. This bilehas 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 juicecannot digest. 

~8. ~ The pancreatic juice does the same kind of work that is done by thesaliva, the gastric juice, and the bile. It also finishes up the workdone by these fluids. It is one of the most important of all thedigestive juices. 

~9. ~ The intestinal juice digests nearly all the different elements ofthe food, so that it is well fitted to complete the wonderful process bywhich 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 pancreaticjuice, and intestinal juice, it is gradually moved along the intestines. After all those portions of food which can be digested have beensoftened and dissolved, they are ready to be taken into the blood anddistributed through the body. 

~11. Absorption. ~--If you put a dry sponge into water, it very soonbecomes wet by soaking up the water. Indeed, if you only touch a cornerof the sponge to the water, the whole sponge will soon become wet. Wesay that the sponge absorbs the water. It is in a somewhat similar waythat the food is taken up or absorbed by the walls of the stomach andintestines. When the food is absorbed, the greater part of it is takeninto the blood-vessels, of which we shall learn in a future lesson. 

~12. Liver Digestion. ~--After the food has been absorbed, the most of itis carried to the liver, where the process of digestion is completed. The liver also acts like an inspector to examine the digested food andremove 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 digestedfats, 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 veinnear the heart. 

SUMMARY. 

How a mouthful of food is digested:

1. It is first masticated--that is, it is chewed and moistened withsaliva. 

2. Then it is swallowed, passing through the oesophagus to thestomach. 

3. There it is acted upon, and a part of it digested by the gastricjuice. 

4. It is then passed into the small intestine, where it is acted upon bythe bile, the pancreatic fluid, and the intestinal juice. 

5. The digested food is then absorbed by the walls of the stomach andintestines. 

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 emptiedinto a vein near the heart. 

CHAPTER IX. 

BAD HABITS IN EATING. 

~1. Eating too Fast. ~--A most common fault is eating too fast. When thefood is chewed too rapidly, and swallowed too quickly, it is notproperly divided and softened. Such food cannot be easily acted upon bythe various digestive juices. 

~2. Eating too Much. ~--A person who eats food too rapidly is also verylikely to injure himself by eating too much. The digestive organs areable to do well only a certain amount of work. When too much food iseaten, none of it is digested as well as it should be. Food which is notwell digested will not nourish the body. 

~3. Eating too Often~--Many children make themselves sick by eating toooften. It is very harmful to take lunches or to eat at other than theproper meal-times. The stomach needs time to rest, just as our legs andarms and the other parts of the body do. For the same reason, it is wellfor us to avoid eating late at night. The stomach needs to sleep withthe 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 slowlythat 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 takecare to eat at regular hours. We ought not to eat when we are verytired. 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, asthey 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, andwhich may make us sick. The colors used in candies are sometimespoisonous. The flavors used in them are also sometimes very harmful. 

~6. Fatty Foods Hurtful. ~--Too much butter, fat meats, and other greasyfoods are hurtful. Cream is the most digestible form of fat, because itreadily dissolves in the fluids of the stomach, and mixes with the otherfoods without preventing their digestion. Melted fats are especiallyharmful. Cheese, fried foods, and rich pastry are very poor foods, andlikely to cause sickness. 

~7. Eating too many Kinds of Foods. ~--Children should avoid eatingfreely of flesh meats. They ought also to avoid eating allhighly-seasoned dishes, and taking too many kinds of food at a meal. Asimple diet is much the more healthful. Milk and grain foods, asoatmeal, cracked wheat, graham bread, with such delicious fruits asapples, pears, and grapes, are much the best food for children. 

~8. Avoid Use of Cold Foods. ~--We ought not to take very cold foods orliquids with our meals. Cold foods, ice-water, and other iced drinksmake the stomach so cold that it cannot digest the food. For this reasonit is very harmful to drink iced water or iced tea, or to eat ice-creamat meals. These things are injurious to us at any time, but they do thegreatest amount of harm when taken with the food. 

~9. Things sometimes Eaten which are not Foods. ~--Things which are notfoods are often used as foods, such as mustard, pepper, and the variouskinds of seasonings. Soda, saleratus, and baking-powders also belong tothis 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 thatall condiments and other substances which are not foods are harmful isin the case of common salt. This is very commonly used among civilizednations, although there are many barbarous tribes that never taste it. It is quite certain that much more salt is used than is needed. Whenmuch salt is added to the food, the action of the digestive fluids isgreatly hindered. Salt meats, and other foods which have much salt addedto them, are hard to digest because the salt hardens the fibres of themeat, so that they are not easily dissolved by the digestive fluids. 

~11. Care of the Teeth. ~--The teeth are the first organs employed in thework of digestion. It is of great importance that they should be kept inhealth. Many persons neglect their teeth, and treat them so badly thatthey begin to decay at a very early age. 

~12. ~ The mouth and teeth should be carefully cleansed immediately onrising in the morning, and after each meal. All particles of food shouldbe removed from between the teeth by carefully rubbing both the innerand the outer surfaces of the teeth with a soft brush, and rinsing verythoroughly with water. A little soap may be used in cleansing the teeth, but clear water is sufficient, if used frequently and thoroughly. Theteeth should not be used in breaking nuts or other hard substances. Theteeth are brittle, and are often broken in this way. The use of candyand too much sweet food is also likely to injure the teeth. 

~13. ~ Some people think that it is not necessary to take care of thefirst set of teeth. This is a great mistake. If the first set are lostor are unhealthy, the second set will not be as perfect as they shouldbe. It is plain that we should not neglect our teeth at any time oflife. 

~14. Tobacco. ~--When a person first uses tobacco, it is apt to make himvery sick at the stomach. After he has used tobacco a few times it doesnot make him sick, but it continues to do his stomach and other organsharm, and after a time may injure him very seriously. Smokers sometimessuffer from a horrible disease of the mouth or throat known as cancer. 

~15. Effects of Alcohol upon the Stomach. ~--If you should put a littlealcohol into your eye, the eye would become very red. When men takestrong liquors into their stomachs, the delicate membrane lining thestomach becomes red in the same way. Perhaps you will ask how do we knowthat alcohol has such an effect upon the stomach. More than sixty yearsago there lived in Michigan a man named Alexis St. Martin. One day hewas, by accident, shot in such a way that a large opening was made rightthrough the skin and flesh and into the stomach. The good doctor whoattended him took such excellent care of him that he got well. But whenhe recovered, the hole in his stomach remained, so that the doctor couldlook in and see just what was going on. St. Martin sometimes drankwhiskey, and when he did, the doctor often looked into his stomach tosee what the effect was, and he noticed that the inside of the stomachlooked very red and inflamed. 

~16. ~ If St. Martin continued to drink whiskey for several days, thelining of the stomach looked very red and raw like a sore eye. A sorestomach cannot digest food well, and so the whole body becomes sick andweak. What would you think of a man who should keep his eyes always soreand inflamed and finally destroy his eyesight by putting pepper oralcohol or some other irritating substance into them every day? Is itnot equally foolish and wicked to injure the stomach and destroy one'sdigestion by the use of alcoholic drinks? Alcohol, even when it is notvery strong, not only hurts the lining of the stomach, but injures thegastric juice, so that it cannot digest the food well. 

~17. Effects of Alcohol upon the Liver. ~--The liver, as well as thestomach, is greatly damaged by the use of alcohol. You will recollectthat nearly all the food digested and absorbed is filtered through theliver before it goes to the heart to be distributed to the rest of thebody. In trying to save the rest of the body from the bad effects ofalcohol, the liver is badly burned by the fiery liquid, and sometimesbecomes so shrivelled up that it can no longer produce bile and performits other duties. Even beer, ale, and wine, which do not contain so muchalcohol as do rum, gin, and whiskey, have enough of the poison in themto do the liver a great deal of harm, and to injure many other organs ofthe 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 beeaten. 

3. The teeth must be carefully used and kept clean. 

4. Tobacco-using does the stomach harm, and sometimes causes cancer ofthe mouth. 

5. Alcohol injures the gastric juice, and causes disease of the stomachand the liver. 

CHAPTER X. 

A DROP OF BLOOD. 

~1. The Blood. ~--Did you ever cut or prick your finger so as to make itbleed? Probably you have more than once met with an accident of thissort. All parts of the body contain blood. If the skin is broken in anyplace the blood flows out. 

~2. ~ How many of you know what a microscope is? It is an instrumentwhich magnifies objects, or makes them look a great deal larger thanthey really are. Some microscopes are so powerful that they will make alittle speck of dust look as large as a great rock. 

~3. The Blood Corpuscles. ~--If you should look at a tiny drop of bloodthrough 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. Mostof them are slightly reddish, and give to the blood its red color. Avery few are white. 

~5. Use of the Corpuscles. ~--Do you wonder what these peculiar littlecorpuscles do in the body? They are very necessary. We could not live amoment without them. We need to take into our bodies oxygen from theair. It is the business of the red corpuscles to take up the oxygen inthe lungs and carry it round through the body in a wonderful way, ofwhich we shall learn more in a future lesson. 

~6. ~ The white corpuscles have something to do with keeping the body ingood repair. They are carried by the blood into all parts of the bodyand stop where they are needed to do any kind of work. They may becompared to the men who go around to mend old umbrellas, and to do otherkinds of tinkering. It is thought that the white corpuscles turn intored ones when they become old. 

~7. ~ The corpuscles float in a clear, almost colorless fluid whichcontains the digested food and other elements by which the body isnourished. 

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, whichnourishes the body. 

CHAPTER XI. 

WHY THE HEART BEATS. 

~1. ~ If you place your hand on the left side of your chest, you willfeel something beating. If you cannot feel the beats easily, you may runup and down stairs two or three times, and then you can feel them verydistinctly. How many of you know the name of this curious machine insidethe 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 keepspumping away during our whole lives. If it should stop, even for aminute or two, we would die. If you will place your hand over your heartand count the beats for exactly one minute, you will find that it beatsabout seventy-five or eighty times. When you are older, your heart willbeat a little more slowly. If you count the beats while you are lyingdown, you will find that the heart beats more slowly than when you aresitting or standing. When we run or jump, the heart beats much harderand faster. 

~3. Why the Heart Beats. ~--We have learned in preceding lessons that thedigested food is taken into the blood. We have also learned that bothwater and oxygen are taken into the blood. Thus the blood contains allthe materials that are needed by the various parts of the body to makegood the wastes that are constantly taking place. But if the blood wereall in one place it could do little good, as the new materials areneeded in every part of the body. There has been provided a wonderfulsystem of tubes running through every part of the body. By means ofthese tubes the blood is carried into every part where it is required. These tubes are connected with the heart. When the heart beats, itforces the blood through the tubes just as water is forced through apipe by a pump or by a fire-engine. 

~4. The Heart Chambers. ~--The heart has four chambers, two upper andtwo lower chambers. The blood is received into the upper chambers, andis then passed down into the lower chambers. From the lower chambers itis 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 carriedare called _blood-vessels_. There are three kinds of blood-vessels. Oneset 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 fromthe heart by many very small vessels. These minute, hairlike vessels arecalled _capillaries_ (cap´-il-la-ries). 

~6. The Arteries. ~--An artery leads out from the lower chamber of eachside of the heart. The one from the right side of the heart carries theblood only to the lungs. The one from the left side of the heart carriesblood 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 aortabegins to send out branches to various organs. These divide in thetissues again and again until they become so small that only onecorpuscle 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 formlarger ones, the veins. The small veins join to form larger ones, untilfinally all are gathered into two large veins which empty into the upperchamber of the right side of the heart. The veins which carry blood fromthe lungs to the heart empty into the upper chamber of the left side ofthe heart. 

~8. What is Done in the Blood-Vessels. ~--While the blood is passingthrough the small blood-vessels in the various parts of the body, eachpart takes out just what it needs to build up its own tissues. At thesame time, the tissues give in exchange their worn-out or waste matters. The red blood corpuscles in the capillaries give up their oxygen, andthe blood receives in its stead a poisonous substance calledcarbonic-acid gas. 

~9. Red and Blue Blood. ~--While in the arteries the blood is of a brightred color; but while it is passing through the capillaries the colorchanges to a bluish red or purple color. The red blood is called_arterial blood_, because it is found in the arteries. The purple bloodis called _venous blood_, because it is found in the veins. The loss ofoxygen in the corpuscles causes the change of color. 

~10. Change of Blood in the Lungs. ~--Exactly the opposite change occursin the blood when it passes through the lungs. The blood which has beengathered up from the various parts of the body is dark, impure blood. Inthe lungs this dark blood is spread out in very minute capillaries andexposed to the air. While passing through the capillaries of the lungs, the blood gives up some of its impurities in exchange for oxygen fromthe air. The red corpuscles absorb the oxygen and the color of the bloodchanges from dark purple to bright red again. The purified blood is thencarried back to the upper chamber of the left side of the heart throughfour large veins. The blood is now ready to begin another journey aroundthe body. 

~11. The Pulse. ~--If you place your finger on your wrist at just theright 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 thewrist at each beat of the heart. The pulse can be felt at the neck andin 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, onlyabout as large as your fist, and yet it does an amount of work which isalmost beyond belief. Each time it beats, it does as much work as yourarm would do in lifting a large apple from the ground to your mouth. Itbeats when we are asleep as well as when we are awake. When we run weknow by the way in which it beats that it is working very fast. Do youknow how much a ton is? Well, in twenty-four hours the heart does asmuch work as a man would do in lifting stones enough to weigh more thanone hundred and twenty tons. 

~13. The Lymphatics. ~--While the blood is passing through thecapillaries, some of the white corpuscles escape from the blood-vessels. What do you suppose becomes of these runaway corpuscles? Nature hasprovided a way by which they can get back to the heart. In the littlespaces among the tissues outside of the blood-vessels very minutechannels called _lymph channels_ or _lymphatics_ (lym--phat´-ics) begin. The whole body is filled with these small channels, which run togethermuch like the meshes of a net. In the centre of the body the smalllymphatics run into large ones, which empty into the veins near theheart. This is the way the stray white blood corpuscles get back intothe blood. 

~14. The Lymph. ~--In the lymph channels the white corpuscles float in acolorless fluid called _lymph_. The lymph is composed of the fluidportion of the blood which has soaked through the walls of the smallvessels. The chief purpose of the lymphatics is to carry the lymph fromthe tissues back to the heart. 

~15. Lymphatic Glands. ~--Here and there, scattered through the body, areoval structures into each of which many lymphatic vessels are found torun, 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 wonderfulstructures in the body. It is no wonder, then, that alcohol, tobacco, and other narcotics and stimulants produce their most deadly effectsupon these delicate organs. What these effects are we shall learn morefully 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 allparts of the body. 

4. These tubes are connected with the heart. 

5. The vessels which carry blood away from the heart are calledarteries, and those which carry blood back to the heart are calledveins. 

6. The arteries and veins are connected by small tubes calledcapillaries. 

7. The blood found in the arteries is red; that in the veins is darkblue or purple. 

8. The color of the blood changes from red to blue in going through thecapillaries. 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 passingthrough the capillaries of the lungs. The change is due to the oxygenwhich 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 bloodinto different parts of the body. 

13. Some of the white blood corpuscles escape from the blood-vesselsthrough the thin walls of the capillaries. 

14. These corpuscles return to the heart through small vessels calledlymph channels or lymphatics. 

15. The lymphatics in many parts of the body run into small roundishbodies called lymphatic glands. 

16. The object of the lymphatics is to remove from the tissues andreturn to the general circulation the lymph and white blood corpuscleswhich 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 thebody. If we take good care of it, it will do good service for us duringa long life. Let us notice some ways in which the heart is likely to beinjured. 

~2. Violent Exercise. ~--Did you ever run so hard that you were out ofbreath? Do you know why you had to breathe so fast? It was because theviolent exercise made your heart beat so rapidly that the blood couldnot get out of the lungs as fast as the heart forced it in. The lungsbecame so filled with blood that they could not do their work well. Sometimes, when a person runs very fast or takes any kind of violentexercise, the lungs become so filled with blood that a blood-vessel isbroken. The person may then bleed to death. It is very unwise to overtaxthe heart in any way, for it may be strained or otherwise injured, sothat it can never again do its work properly. 

~3. Effects of Bad Air. ~--Bad air is very harmful to the heart and tothe blood also. We should always remember that the blood of the bodywhile 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 inother places where the air becomes foul, people often faint from theeffects of the impure air upon the heart. It is important that the airof the rooms in which we live and sleep should be kept very pure by goodventilation. 

~4. Effects of Bad Food. ~--The blood is made from what we eat, and if weeat impure and unwholesome food, the blood becomes impure. We ought toavoid the use of rich or highly-seasoned foods, candies, and all foodswhich are not nutritious. They not only injure the blood by making itimpure, but they cause poor digestion. 

~5. Plenty of Sleep Necessary. ~--If we should take a drop of blood fromthe finger of a person who had not had as much sleep as he needed, andexamine it with a microscope, we should find that there were too few ofthe little red-blood corpuscles. This is one reason why a person who hasnot had sufficient sleep looks pale. 

~6. Proper Clothing. ~--We should be properly clothed, according to theweather. In cold weather we need very warm clothing. In warm weather weshould wear lighter clothing. Our clothing should be so arranged that itwill keep all parts of the body equally warm, and thus allow the bloodto circulate properly. The feet are apt to be cold, being so far awayfrom the heart, and we should take extra pains to keep them warm anddry. 

~7. Effects of Excessive Heat. ~--In very hot weather, many persons areinjured by exposing themselves to the sun too long at a time. Personswho drink intoxicating liquors are very often injured in this way, andsometimes die of sunstroke. 

~8. Effects of Anger. ~--When a person gets very angry, the heartsometimes almost stops beating. Indeed, persons have died instantly in afit of passion. So you see it is dangerous for a person to allow himselfto become very angry. 

~9. Effects of Alcohol upon the Blood. ~--If you should take a drop ofblood upon your finger, and put it under the microscope, and then add alittle alcohol to it, you would see that the corpuscles would be quicklydestroyed. In a few seconds they would be so shrivelled up that no onecould tell that they had ever been the beautiful little corpuscles whichare so necessary to health. When alcohol is taken as a drink, it doesnot destroy the corpuscles so quickly, but it injures them so that theyare 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 oftenlook so blue. 

~10. Alcohol Overworks the Heart. ~--Dr. Parkes, a very learned Englishphysician, took the pains to observe carefully the effects of alcoholupon the heart of a soldier who was addicted to the use of liquor. Hecounted the beats of the soldier's pulse when he was sober; and thencounted them again when he was using alcohol, and found that when thesoldier took a pint of gin a day his heart was obliged to do one fourthmore work than it ought to do. 

~11. Effects of Alcohol upon the Blood-Vessels. ~--If you put your handsinto warm water, they soon become red. This is because the blood-vesselsof 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 isthis that causes the flushed cheeks and the red eyes of the drunkard. Sometimes, after a man has been using alcohol a long time, theblood-vessels of his face remain enlarged all the time. This makes hisnose grow too fast, and so in time it gets too large, and then he has arum-blossom. 

~12. Effects of Tobacco on the Heart and the Blood. ~--When a boy firsttries to use tobacco, it makes him feel very sick. If you should feelhis pulse just then, you would find it very weak. This means that theheart is almost paralyzed by the powerful poison of the tobacco. Tobaccoalso 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 heavyand irregular beating of the heart. 

~14. Taking Cold. ~--People usually "catch cold" by allowing thecirculation to become disturbed in some way, as by getting the feet wet, being chilled from not wearing sufficient clothing, sitting in adraught, and in other similar ways. It is very important for you to knowthat a cold is a serious thing, and should be carefully avoided. 

~15. Hemorrhage~ (hem´-or-rhage) ~or Loss of Blood. ~--A severe loss ofblood is likely to occur as the result of accidents or injuries ofvarious sorts, and it is important to know what to do at once, as theremay not be time to send for a doctor before it will be too late to savethe injured person's life. Here are a few things to be remembered in allsuch cases:

~16. ~ If the blood from a cut or other wound flows in spurts, and is ofa bright red color, it is from an artery. If it is dark-colored, andflows in a steady stream, it is from a vein. 

~17. How to Stop the Bleeding of Wounds. ~--If the bleeding vessel is anartery, apply pressure on the side of the wound next to the heart. Ifthe bleeding is from a vein, apply it on the opposite side. It isgenerally best to apply pressure directly over the wound or on bothsides. 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 ortowel around the wounded part and twist it very tight. If an arm or limbis the part injured, the person should be made to lie down, and theinjured part should be held up. This is of itself an excellent means ofstopping hemorrhage. 

~18. Nose-Bleed. ~--For nose-bleed a very good remedy is holding one orboth hands above the head. The head should be held up instead of beingbent forward, and the corner of a dry handkerchief should be pressedinto the bleeding nostril. It is well to bathe the face with very hotwater, and to snuff hot water into the nostril if the bleeding is verysevere. If the bleeding is very bad or is not readily stopped, aphysician 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 indifferent 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 shouldnever be neglected. 

14. When an artery is wounded, the blood is bright red and flows inspurts. 

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 woundtowards 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 asmall bit of candle, a fruit jar, or a bottle with a large mouth, and apiece of wire about a foot long. Let us notice carefully what we areabout to do and what happens. 

~2. ~ We will fasten the candle to the end of the wire. Now we will lightit, and next we will let it down to the bottom of the jar. Now place thecover on the top of the jar and wait the results. Soon the candle burnsdimly and in a little time the light goes out altogether. 

~3. ~ What do you think is the reason that the candle will not burn whenshut up in a bottle? A candle uses air when it burns. If shut up in asmall, tight place, it soon uses up so much air that it can burn nolonger. Try the experiment again, and when the candle begins to burndimly, take it out quickly. We see that at once the light burns brightagain. 

~4. ~ Suppose we shut the stove draught tight, what is the result? Thefire will burn low, and after a time it will probably go out. Why isthis? Evidently the stove needs air to make the wood or coal burn, justas the candle needs air to make it burn. 

~5. Animals Die without Air. ~--If you should shut up a mouse or anyother small animal in a fruit-jar, its life would go out just as thelight of the candle went out. The little animal would die in a shorttime. A child shut up in a close place would die from the same cause ina very little time. In fact, many children are dying every day for wantof a sufficient supply of pure air. 

~6. Oxygen. ~--The reason why animals need air, and why the fire will notburn without it, is that the air contains _oxygen_, and it is the oxygenof the air which burns the wood or coal and produces heat. So it is theoxygen that burns in our bodies and keeps us warm. 

~7. ~ When wood and coal are burned, heat is produced; but some parts ofthe fuel are not made into heat. While the fire burns, smoke escapesthrough the pipe or chimney; but a part of the fuel remains in the stovein 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 bodiesproduces something similar to the smoke and ashes produced by the firein a stove. The smoke is called _carbonic-acid gas_, [A] an invisiblevapor, and escapes through the lungs. The ashes are various waste andpoisonous matters which are formed in all parts of the body. These wastematters are carried out of the body through the skin, the kidneys, theliver, 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 doespass out. Get two drinking-glasses and a tube. A glass tube is best, buta straw will do very well. Put a little pure water into one glass andthe same quantity of lime-water into the other glass. Now put one end ofthe 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 andsee that no change has taken place. Now breathe through the lime-waterin the same way. After breathing two or three times, you will noticethat the lime-water begins to look milky. In a short time it becomesalmost as white as milk. This is because the lime-water catches thecarbonic-acid gas which escapes from our lungs with each breath, whilethe pure water does not. 

~10. Why we Breathe. ~--By this experiment we learn another reason whywe breathe. We must breathe to get rid of the carbonic-acid gas, whichis brought to the lungs by the blood to be exchanged for oxygen. Thereare two reasons then why we breathe: (_a_) to obtain oxygen; (_b_) toget 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 avery curious way of breathing. He comes to the top of the water, putshis nose out a little, and then drinks the air. You can watch his throatand see him swallowing the air, a mouthful at a time, just as you woulddrink water. 

~12. ~ If you had a chance to see the inside of a frog you would findthere a queer-shaped bag. This is his air-bag. This bag has a tuberunning up to the throat. When the frog comes to the surface of thewater he fills this bag with air. Then he can dive down into the mud outof sight until he has used up the supply of air. When the air has beenchanged to carbonic-acid gas, he must come to the surface to empty hisair-bag and drink it full again. 

~13. The Lungs. ~--We do not drink air as the frog does, but like thefrog we have an air-bag in our bodies. Our air-bag has to be emptiedand filled so often that we cannot live under water long at a time, asa frog does. We call this air-bag the lungs. We have learned before thatthe lungs are in the chest. We need so much air and have to change theair in our lungs so often that we would not have time to swallow it as afrog does. So nature has made for us a breathing apparatus of such akind that we can work it like a pair of bellows. Let us now study ourbreathing-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. Thewindpipe divides into two main branches, which subdivide again andagain, until the finest branches are not larger than a sewing-needle. The branches are called _bronchial tubes_. At the end of each tube is acluster of small cavities called _air-cells_. The air-tubes andair-cells are well shown on the following page. 

~15. The Voice-box. ~--If you will place the ends of your fingers uponyour throat just above the breast-bone, you will feel the windpipe, andmay notice the ridges upon it. These are rings of cartilage, a hardsubstance commonly called gristle. The purpose of these rings is to keepthe windpipe open. Close under the chin you can find something whichfeels 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 bymeans of this curious little apparatus we are able to talk and sing. Twolittle 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 curioustrap-door which can be shut down so as to close the entrance to theair-passages of the lungs. This little door has a name rather hard toremember. It is called the _epiglottis_ (ep-i-glot´-tis). The cover ofthe voice-box closes whenever we swallow anything. This keeps food orliquids from entering the air passages. If we eat or drink too fast thevoice-box will not have time to close its little door and prevent ourbeing choked. Persons have been choked to death by trying to swallowtheir food too fast. Do you not think this is a very wonderful door thatcan open and shut just when it should do so without our thinkinganything about it?

~17. The Nostrils and the Soft Palate. ~--The air finds its way to thelungs through the mouth or through the two openings in the nose calledthe _nostrils_. From each nostril, three small passages lead backwardthrough the nose. At the back part of the nasal cavity the passages ofthe two sides of the nose come together in an open space, just behindthe soft curtain which hangs down at the back part of the mouth. Thiscurtain is called the _soft palate_. Through the opening behind thiscurtain 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 areenclosed in a very thin covering, called the _pleura_. The cavity of thechest in which the lungs are suspended is also lined by the pleura. Alimpid fluid exudes from the pleura which keeps it moist, so that whenthe two surfaces rub together, as the lungs move, they do not becomechafed and irritated. 

~19. Walls of the Chest. ~--The ribs form a part of the framework of thechest. The ribs are elastic. The spaces between them are filled up withmuscles, some of which draw the ribs together, while others draw themapart. 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 calledthe _diaphragm_, which divides the trunk into two cavities, the chestand the abdomen. 

~20. How we Use the Lungs. ~--Now let us notice how we use the lungs andwhat takes place in them. When we use a pair of bellows, we take hold ofthe handles and draw them apart. The sides of the bellows are drawnapart so that there is more room between the sides. The air then rushesin to fill the space. When the bellows are full, we press the handlestogether and the air is forced out. 

~21. ~ It is in just this way that we breathe. When we are about to takea long breath, the muscles pull upon the sides of the chest in such away as to draw them apart. At the same time the diaphragm draws itselfdownward. By these means, the cavity of the chest is made larger and airrushes in through the nose or mouth to fill the space. When the musclesstop pulling, the walls of the chest fall back again to their usualposition and the diaphragm rises. The cavity of the chest then becomessmaller and the air is forced out through the nose or mouth. Thisprocess is repeated every time we breathe. 

~22. ~ We breathe once for each four heart-beats. Small children breathemore rapidly than grown persons. We usually breathe about eighteen ortwenty times in a minute. 

~23. How Much the Lungs Hold. ~--Every time we breathe, we take into ourlungs about two thirds of a pint of air and breathe out the samequantity. Our lungs hold, however, very much more than this amount. Aman, 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 allhe can, there is still almost half a gallon of air in his lungs which hecannot breathe out. So you see the lungs hold almost a gallon and a halfof air. 

~24. ~ Do you think you can tell why Nature has given us so much moreroom in the lungs than we ordinarily use in breathing? If you will runup and down stairs three or four times you will see why we need thisextra lung-room. It is because when we exercise vigorously the heartworks very much faster and beats harder, and we must breathe much fasterand fuller to enable the lungs to purify the blood as fast as the heartpumps it into them. 

~25. The Two Breaths. ~--We have learned that the air which we breatheout contains something which is not found in the air which we breathein. This is carbonic-acid gas. How many of you remember how we foundthis out? We can also tell this in another way. If we put a candle downin a wide jar it will burn for some time. If we breathe into the jarfirst, however, the candle will go out as soon as we put it into thejar. This shows that the air which we breathe out contains somethingwhich will put a candle out. This is carbonic-acid gas, which is apoison and will destroy life. 

~26. Other Poisons. ~--The air which we breathe out also contains otherinvisible poisons which are very much worse than the carbonic-acid gas. These poisons make the air of a crowded or unventilated room smell veryunpleasant to one who has just come in from the fresh air. Such air isunfit to breathe. 

~27. The Lungs Purify the Blood. ~--We have learned that the bloodbecomes dark in its journey through the body. This is because it losesits oxygen and receives carbonic-acid gas. While passing through thecapillaries of the lungs, the blood gives out the carbonic-acid gaswhich it has gathered up in the tissues, and takes up a new supply ofoxygen, which restores its scarlet hue. 

~28. How the Air is Purified. ~--Perhaps it occurs to you that with somany people and animals breathing all the while, the air would after atime become so filled with carbonic-acid gas that it would be unfit tobreathe. This is prevented by a wonderful arrangement of Nature. Thecarbonic-acid gas which is so poisonous to us is one of the mostnecessary foods for plants. Plants take in carbonic-acid gas throughtheir leaves, and send the oxygen back into the air ready for us to useagain. 

~29. ~ We have already learned that the oxygen taken in by the lungs iscarried to the various parts of the body by the little blood corpuscles. The effect of strong liquors is to injure these corpuscles so that theycannot carry so much oxygen as they ought to do. For this reason, theblood 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 allthe air he needs, but his blood has been so damaged that he cannot useit. 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. Weneed 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 thewaste matters. 

5. The breathing organs are the windpipe and bronchial tubes, thevoice-box, the epiglottis, the nostrils, the soft palate, the lungs, theair-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 anotherinvisible poison. 

10. A candle will not burn in air which has been breathed, and animalsdie when confined in such air. 

11. The lungs purify the blood. While passing through the lungs, thecolor 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 cannottake 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, orwithout drinking for several days, and still live; but a strong man willdie in a few moments if deprived of air. It is very important that webreathe plenty of pure air. There are many ways in which the air becomesimpure. 

~2. Bad Odors. ~--Anything which rots or decays will in so doing producean unpleasant odor. Bad odors produced in this way are very harmful andlikely to make us sick. Many people have rotting potatoes and othervegetables in their cellars, and swill barrels, and heaps of refuse intheir back yards. These are all dangerous to health, and often give riseto very serious disease. We should always remember that bad odors causedby decaying substances are signs of danger to health and life, and thatthese substances should be removed from us, or we should get away fromthem, as soon as possible. 

~3. Germs. ~--The chief reason why bad odors are dangerous is that theyalmost always have with them little living things called _germs_. Germsare so small that they cannot be seen by the naked eye: it takes astrong microscope to enable us to see them, but they are so powerful todo harm that if we receive them into our bodies they are likely to makeus very sick, and they often cause death. 

~4. Contagious Diseases. ~--You have heard about diphtheria and scarletfever and measles, and other "catching diseases. " When a person is sickwith one of these diseases, the air about him is poisoned with germs orsomething similar, which may give the same disease to other persons whoinhale it. So when a person is sick from one of these diseases, it isvery important that he should be put in a room by himself and shut awayfrom every one but the doctor and the nurse. It is also necessary thatall the clothing and bedding used by the sick person, and everything inthe room, as well as the room itself, should be carefully cleansed anddisinfected when the person has recovered, so as to wipe out every traceof the disease. The writer has known many cases in which persons whohave been sick with some of these diseases were careless and gave thedisease to others who died of it, although they themselves recovered. Doyou not think it very wrong for a person to give to another throughcarelessness a disease which may cause his death?

~5. ~ Unhealthful vapors and odors of various sorts arise from cisternsand damp, close places under a house. Rooms which are shaded and shut upso closely that fresh air and sunshine seldom get into them should beavoided as dangerous to health. 

~6. Breath-Poisoned Air. ~--The most dangerous of all the poisons towhich we are exposed through the air are those of the breath, of whichwe learned in a preceding lesson. We need plenty of fresh air to takethe place of the air which we poison by our breath. Every time webreathe, we spoil at least _half a barrelful of air_. We breathe twentytimes a minute, and hence spoil ten barrels of air in one minute. Howmany barrels would this make in one hour? We need an equal quantity ofpure air to take the place of the spoiled air, or not less than tenbarrels every minute, or _six hundred barrels every hour_. 

~7. Ventilation. ~--The only way to obtain the amount of fresh airneeded, when we are shut up in-doors, is to have some means provided bywhich the fresh air shall be brought in and the old and impure aircarried out. Changing the air by such means is called _ventilation_. Every house, and especially every sleeping-room, should be wellventilated. School-houses, churches, and other places where many peoplegather, need perfect ventilation. Ask your teacher to show you how theschool-room is ventilated; and when you go home, talk to your parentsabout the ventilation of the house in which you live. 

~8. ~ Many people ventilate their houses by opening the doors andwindows. 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, andmakes the floor cold, so that it is difficult to keep the feet warm. Itis much better to have the air warmed by a furnace or some similarmeans, before it enters the rooms. There ought also to be in each room aregister to take the foul air out, so that it will not be necessary toopen the windows. This register should be placed at the floor, becausewhen the pure air enters the room warm, it first rises to the upper partof 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 lungswell in breathing, and to use the entire chest, both the upper and thelower part. Clothing should be worn in such a way that every portion ofthe chest can be expanded. For this reason it is very wrong to wear theclothing tight about the waist. Clothing so worn is likely to cause thelungs to become diseased. 

~10. Bad Habits. ~--Students are very apt to make themselves flat-chestedand round-shouldered by leaning over their desks while writing orstudying. This is very harmful. We should always use great care to siterect and to draw the shoulders well back. Then, if we take pains tofill the lungs well a great many times every day, we shall form thehabit of expanding the lungs, and shall breathe deeper, even when we arenot thinking about doing so. 

~11. Breathing through the Nose. ~--In breathing, we should always takecare to draw the air in through the nose, and not through the mouth. Thenose acts as a strainer, to remove particles of dust which might do harmif allowed to enter the lungs. It also warms and moistens the air incold weather. The habit of breathing through the mouth often gives riseto serious disease of the throat and lungs. 

~12. Effects of Alcohol and Tobacco upon the Lungs. ~--Both alcohol andtobacco produce disease of the breathing organs. Smoking injures thethroat and sometimes causes loss of smell. Serious and even fataldiseases of the lungs are often caused by alcohol. 

~13. ~ Many people suppose that the use of alcohol will save a man fromconsumption. This is not true. A man may become a drunkard by the use ofalcohol, and yet he is more likely to have consumption than he wouldhave been if he had been a total abstainer. "Drunkard's consumption" isone 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, andthus 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 theirrooms and clothing should be carefully cleansed and disinfected. 

5. The breath poisons the air about us. Each breath spoils half abarrelful of air. 

6. We should change the air in our houses, or ventilate them, so that wemay always have pure air. 

7. We should always keep the body erect, and expand the lungs well inbreathing. 

8. The clothing about the chest and waist should be loose, so that thelungs 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 exactlythat it has the precise shape of the body, like a closely fittinggarment. If you will take up a little fold of the skin you will see thatit can be stretched like a piece of india-rubber. Like rubber, when itis 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 andmuch thicker bark, which lay next to the wood of the tree. You can peelthe outer bark off without doing the tree much harm. Indeed, if you willnotice some of the fruit or shade trees in the yard, at home, you willsee that the outer bark of the tree peels itself off, a little at atime, and that new bark grows in its place. If you tear off the innerbark, however, it will injure the tree. It will make it bleed, or causethe sap to run. The sap is the blood of the tree. The bark is the skinof 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 oneskin with an outer and an inner layer. When a person burns himself so asto make a blister, the outer skin, called the _cuticle_, is separatedfrom the inner by a quantity of water or serum poured out from theblood. This causes the blister to rise above the surrounding skin. Ifyou puncture the blister the water runs out. Now we may easily removethe cuticle and examine it. The cuticle, we shall find, looks very muchlike the skin which lines the inside of an egg-shell, and it is almostas thin. 

~4. ~ The cuticle is very thin in most parts of the body, but in someplaces, as the palms of the hands and the soles of the feet, it is quitethick. This is because these parts of the skin come in contact withobjects 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 needleand thread you can easily take a stitch in it without making it bleed orcausing any pain. 

~5. The Pigment. ~--The under side of the cuticle is colored by littleparticles of pigment or coloring matter. The color of this pigmentdiffers in different races. In the negro, the color of the pigment isblack. In some races the pigment is brown. In white persons there isvery little pigment, and in some persons, called albinos, there is noneat all. 

~6. The Inner or True Skin. ~--The inner skin, like the inner bark of atree, is much thicker than the outer skin. It is much more important, and for this reason is sometimes called the _true skin_. It containsnerves 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 seemany coarse lines, and by looking much closer you will see that the palmis completely covered with very fine ridges and furrows. Now, if youexamine these ridges with a magnifying-glass, you will find arrangedalong each ridge a number of little dark spots. Each of these points isthe mouth of a very small tube. This is called a _sweat duct_. Theseducts run down through both the outer and inner layers of the skin. Atthe under side of the true skin the end of the tube is rolled up in acoil, as you can see by looking at the illustration on the followingpage. The coiled parts of the tubes are called _sweat glands_, becausethey separate from the blood the fluid which we call sweat orperspiration. 

~8. The Oil Glands. ~--There are other little glands in the skin whichmake fat or oil. The oil is poured out upon the skin to keep it soft andsmooth. 

[Illustration: THE STRUCTURE OF THE SKIN. ]

~9. The Hair. ~--There are some curious little pockets in the skin. Outof each of these pockets grows a hair. On some parts of the body thehairs are coarse and long; on other parts they are fine and short. 

~10. ~ Many of the ducts leading from the oil glands open into thepockets or pouches from which the hairs grow. The oil makes the hairsoft and glossy. Nature has thus provided an excellent means for oilingthe hair. 

~11. ~ The hair is chiefly useful as a protection. It is also anornament. 

~12. The Nails. ~--The nails of the fingers and the toes grow out oflittle pockets in the skin just as the hairs do. Both the hair and thenails are really parts of the outer skin, which is curiously changed andhardened. The nails lie upon the surface of the true skin and grow fromthe under side as well as from the little fold of skin at the root ofthe nail. They are made to give firmness and protection to the ends ofthe fingers and toes. The nails of the fingers are also useful inpicking 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 atwork removing from the blood particles which have been worn out and canbe of no further use. If we get very warm, or if we run or work veryhard, the skin becomes wet with sweat. In a little while, if we stop torest, 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 onall the time, but we do not sweat so much when we are quiet and are nottoo warm, and so the sweat dries up as fast as it is produced, and we donot see it. Nearly a quart of sweat escapes from the skin daily. 

(2) _Breathing through the Skin. _--We breathe to a slight extent throughthe skin. There are some lower animals which breathe with their skinsaltogether. A frog can breathe with its skin so well that it can livefor some time after its lungs have been removed. Breathing is animportant part of the work of the skin, and we should be careful, bykeeping it clean and healthy, to give it a good chance to breathe allthat it can. 

(3) _The Skin Absorbs. _--The skin absorbs many substances which come incontact with it, and hence should be kept clean. If the foul substanceswhich are removed in the sweat are allowed to remain upon the skin, theymay be taken back into the system and thus do much harm. 

(4) _The Skin has Feeling. _--When anything touches the skin we know itby the feeling. We can tell a great many things about objects by feelingof them. If we happen to stick a pin into the skin we feel pain. We arealso able to tell the difference between things which are hot and thosewhich are cold. Thus the sense of feeling which the skin has is veryuseful to us. 

(5) _The Skin Protects the Body. _--The skin is a natural clothing whichprotects us much better than any other kind of clothing could. It is sosoft and pliable that it cannot hurt the most delicate part which itcovers, 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 givesthe skin its color. 

3. The true skin has blood-vessels and nerves, but the cuticle has noblood-vessels and very few nerves. 

4. In the true skin are glands which produce sweat, and others whichmake fat, or oil. 

5. The nails are really a part of the skin. They are firm and hard, andprotect the ends of the fingers and the toes. 

6. The hair grows from the true skin. The hair is made soft and glossyby oil from the oil glands of the skin. 

7. The skin is a very useful organ. It removes waste matters, itbreathes, 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 greatcelebration, a little boy was covered all over with varnish and goldleaf, so as to make him represent an angel. The little gilded boy lookedvery pretty for a short time, but soon he became very sick, and in a fewhours he was dead. Can you guess what made him die? He died because thepores of his skin were stopped up, and the sweat glands could not carryoff the poisonous matter from his body. 

~2. Cleanliness. ~--Did you ever know of a boy who had his skinvarnished? Not exactly, perhaps; but there are many boys who do not havetheir skins washed as often as they ought to be, and the sweat and oiland dead scales form a sort of varnish which stops up the little ductsand prevents the air from getting to the skin, almost as much as a coatof varnish would do. 

~3. The Sweat Glands. ~--The sweat glands and ducts are like littlesewers, made to carry away some of the impurities of the body. There areso many of them that, if they were all put together, they would make atube two or three miles long. These little sewers drain off almost aquart of impurities in the form of sweat every day. So you see that itis very important for the skin to be kept clean and healthy. 

~4. Bathing. ~--A bird takes a bath every day. Dogs and many otheranimals like to go into the water to bathe. Some of you have seen agreat elephant take a bath by showering the water over himself with histrunk. To keep the skin healthy we should bathe frequently. 

~5. ~ When we take a bath for cleanliness it is necessary to use a littlesoap, so as to remove the oil which is mixed up with the dry sweat, deadscales, and dirt which may have become attached to the skin. 

~6. ~ It is not well to take hot baths very often, as they have atendency to make the skin too sensitive. Bathing in cool water hardensthe skin, and renders one less likely to take cold. 

~7. The Clothing. ~--The skin should be protected by proper clothing, butit is not well to wear more than is necessary, as it makes the skin sosensitive that one is liable to take cold. 

~8. The Proper Temperature of Rooms. ~--It is also very unwise for aperson to keep the rooms in which he lives too warm, and to stay toomuch in-doors, as it makes him very liable to take cold when he goesout-of-doors. One who is out of doors in all kinds of weather seldomtakes cold. 

~9. Care of the Hair and the Nails. ~--The scalp should be kept clean bythorough and frequent washing and daily brushing. Hair oils are seldomneeded. If the skin of the head is kept in a healthy condition, the hairrequires no oil. 

~10. ~ The habit of biting and picking the fingernails is a veryunpleasant one, and keeps the nails in a broken and unhealthy condition. The nails should be carefully trimmed with a sharp knife or a pair ofscissors. 

~11. Effects of Narcotics and Stimulants upon the Skin. ~--Alcohol, tobacco, opium, and all other narcotics and stimulants have a bad effectupon 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 toomuch 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 ofthe body. They are in the cavity of the abdomen, near the back-bone, upunder the lower border of the ribs. Perhaps you have seen the kidneys ofa sheep or a hog. If you have, you know very nearly how the kidneys ofour own bodies appear. 

[Illustration: KIDNEY. ]

~2. The Work of the Kidneys. ~--The work of the kidneys is to separatefrom the blood certain very poisonous substances, which would soon causeour death if they were not removed. It is very important to keep theseuseful organs in good health, because a person is certain to die verysoon when the kidneys are in any way seriously injured. 

~3. How to Keep the Kidneys Healthy. ~--One way of keeping the kidneys ingood health is to drink plenty of pure water, and to avoid eating toomuch meat and rich food. Pepper, mustard, and other hot sauces are veryharmful to the kidneys. 

~4. Importance of Keeping the Skin Clean. ~--The work of the kidneys isvery similar to that of the skin; and when the skin does not do its fullduty, the kidneys have to do more than they should, and hence are likelyto become diseased. For this reason, persons who allow their skins tobecome inactive by neglecting to bathe frequently are apt to havedisease of the kidneys. 

~5. Effects of Alcohol and Tobacco upon the Kidneys. ~--A piece of beefplaced in alcohol soon becomes dry and hard, and shrivels up as thoughit had been burned. The effect upon the kidneys of drinking strongliquor 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 intheir work. 

2. The kidneys remove from the blood some poisonous substances. 

3. To keep the kidneys healthy we should drink plenty of water, avoidirritating foods and drinks, and keep the skin in health by properbathing. 

4. The drinking of strong liquors often causes incurable disease of thekidneys. 

CHAPTER XVIII. 

OUR BONES AND THEIR USES. 

~1. The Bones. ~--In an earlier chapter we learned something about thebones. This we must try to recall. You will remember that we called thebones the framework of the body, just as the timbers which are first putup in building a house are called its frame. 

~2. The Skeleton. ~--All the bones together make up the _skeleton_. (Seepage 95. ) There are about two hundred bones in all. They are of manydifferent 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 thelargest 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 bonesof each part. 

~4. The Skull. ~--The _skull_ is somewhat like a shell. It is made of anumber of bones joined together in such a way as to leave a hollow placeinside to hold the brain. The front part of the skull forms theframework of the face and the jaws. In each ear there are three curiouslittle 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 trunkform a framework to support and protect the various organs within itscavities. 

~6. The Ribs. ~--There are twelve _ribs_ on each side. The ribs join theback-bone at the back. They are connected by cartilage to thebreast-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 containand protect the heart and the lungs. 

~7. The Pelvis. ~--The pelvis is at the lower part of the trunk. It isformed by three bones, closely joined together. The large bones ateither side are called the hip-bones. Each hip-bone contains a deepround cavity in which the upper end of the thigh-bone rests. 

~8. The Back-bone. ~--The _back-bone_, or spinal column, is made up oftwenty-four small bones, joined together in such a way that the wholecan be bent in various directions. The skull rests upon the upper end ofthe spinal column. The lower end of the back-bone forms a part of thepelvis. 

[Illustration: SKELETON OF A MAN. ]

~9. The Spinal Canal. ~--Each of the separate bones that make up theback-bone has an opening through it, and the bones are so arranged, oneabove 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 opensinto the cavity of the skull. Through this canal there passes a peculiarsubstance called the _spinal cord_, of which we shall learn more atanother time. 

~10. The Arms. ~--Each of the arms has five bones, besides the smallbones of the hand. They are the _collar-bone_, which connects theshoulder to the breast-bone, the _shoulder-blade_, at the back of theshoulders, the _upper arm-bone_, between the shoulder and the elbow, andthe two _lower arm-bones_, between the elbow and the wrist. There areeight little bones in the wrist, five in that part of the hand next tothe wrist, and fourteen in the fingers and thumb. 

~11. The Legs. ~--The bones of the leg are the _thigh_ or _upperleg-bone_, the _knee-pan_ or _knee-cap_, which covers the front of theknee, the two bones of the _lower leg_, the _heel-bone_ and six otherbones in the _ankle_, five bones in that part of the foot next to theankle, and fourteen bones in the _toes_. 

~12. Use of the Bones. ~--The skeleton is not only necessary as aframework for the body, but it is useful in other ways. Some of thebones, as the skull, protect delicate parts. The brain is so soft anddelicate that it would be very unsafe without its solid bony covering. The spinal cord also needs the protection which it finds in the strongbut flexible back-bone. The bones help to move our hands and arms, andassist us in walking. 

~13. The Joints. ~--The places where two or more bones are fastenedtogether are called _joints_. Some joints we can move very freely, asthose of the shoulder and the hip. Others have no motion at all, asthose of the bones of the skull. 

~14. Cartilage. ~--The ends of bones which come together to form a jointare covered with a smooth, tough substance, which protects the bone fromwear. This is called _gristle_ or _cartilage_. You have, no doubt, seenthe 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 thebones move upon each other very easily. If the joints were dry, everymovement of the body would be very difficult and painful. 

~16. ~ The bones are held together at the joints by means of strong bandscalled _ligaments_. 

~17. How the Bones are Made. ~--The bones are not so solid as they seemto be. The outside of most bones is much harder and firmer than theinside. Long bones, like those of the arms and the legs, are hollow. Thehollow space is filled with _marrow_, in which are the blood-vesselswhich nourish the bone. 

~18. An Experiment. ~--If you will weigh a piece of bone, then burn it inthe fire for several hours, and then weigh it again, you will find thatit has lost about one third of its weight. You will also notice that ithas become brittle, and that it seems like chalk. 

~19. Why the Bones are Brittle. ~--The hard, brittle portion of a bonewhich is left after it has been burned contains a good deal of chalk andother earthy substances, sometimes called bone-earth. It is this whichmakes the bones so hard and firm that they do not bend by the weight ofthe body. When we are young, the bones have less of this bone-earth, andso they bend easily, and readily get out of shape. When we get old, theycontain so much bone-earth that they become more brittle, and oftenbreak very easily. 

~20. ~ A person's height depends upon the length of his bones. The use ofalcohol and tobacco by a growing boy has a tendency to stunt the growthof 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 calledcartilage or gristle. 

7. The joints are enabled to work easily by the aid of a fluid secretedfor that purpose. 

8. The ends of the bones are held together in a joint by means ofligaments. 

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 thebones. 

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 thesubstances which are needed to make healthy bone, the bones will becomeunhealthy. 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 somuch more healthful than that made from very fine white flour. In makingfine 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 verygood food for making healthy bones. 

~2. Bones of Children. ~--Sometimes little children try to walk beforethe bones have become hard enough to support the weight of the body. This causes the legs to become crooked. In some countries young childrenwork in factories and at various trades. This is wrong, because itdwarfs their growth, and makes them puny and sickly. 

~3. Improper Positions. ~--The bones are so soft and flexible when weare young that they are very easily bent out of shape if we allowourselves 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 tokeep the shoulders well back and the chest well expanded, so that we maynot grow misshapen and deformed. Many boys and girls have ugly curves intheir backbones which have been caused by sitting at high desks with oneelbow on the desk, thus raising the shoulder of that side so high thatthe spine becomes crooked. The illustrations on this and the followingpage 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 beof proper height. The seats should be low enough to allow the feet torest easily upon the floor, but not too low. The desk should be of sucha height that, in writing, one shoulder will not be raised above theother. If a young person bends the body forward, he will, after a time, become round-shouldered and his chest will become so flattened that thelungs 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, areways in which young persons often grow out of shape. 

[Illustration: SEAT TOO HIGH. ]

~7. The Clothing. ~--Wearing the clothing tight about the waist oftenproduces serious deformities of the bones of the trunk, and makes thechest so small that the lungs have not room to act properly. Tight orhigh-heeled shoes also often deform and injure the feet and make thegait stiff and awkward. 

~8. Broken Bones. ~--By rough play or by accident the bones may be brokenin two just as you might break a stick. If the broken parts are placedright, Nature will cement them together and make the bone strong again;but sometimes the bones do not unite, and sometimes they grow togetherout of proper shape, so that permanent injury is done. 

~9. Sprains. ~--In a similar manner the ligaments which hold the bonestogether, in a joint, are sometimes torn or over-stretched. Such anaccident is called a sprain. A sprain is a very painful accident, and ajoint injured in this way needs to rest quite a long time so that thetorn ligaments may grow together. 

~10. Bones out of Joint. ~--Sometimes the ligaments are torn so badlythat the ends of the bones are displaced, and then we say they are putout of joint. This is a very bad accident indeed, but it often happensto boys while wrestling or playing at other rough games. 

~11. ~ Children sometimes have a trick of pulling the fingers to causethe knuckles to "crack. " This is a very foolish and harmful practice. Itweakens the joints and causes them to grow large and unsightly. 

~12. ~ When a man uses alcohol and tobacco, their effects upon the bonesare not so apparent as are the effects upon the blood, the nerves, andother organs; but when the poisonous drugs are used by a growing boy, their damaging influence is very plainly seen. A boy who smokes cigarsor cigarettes, or who uses strong alcoholic liquors, is likely to be sostunted that even his bones will not grow of a proper length and he willbecome 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 causesof 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 ligamentsmay 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 themutton-chops which they eat for breakfast? From the butcher, you willsay; 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 bya soft substance, the flesh. When the skin of an animal has been takenoff, we can see that some of the flesh is white or yellow and some of itis 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 differentmuscles in the body. They are arranged in such a way as to cover thebones and make the body round and beautiful. They are of different formsand sizes. 

~3. ~ With a very few exceptions the muscles are arranged in pairs; thatis, we have two alike of each form and size, one for each side of thebody. 

~4. How a Muscle is Formed. ~--If you will examine a piece of corned orsalted beef which has been well boiled, you will notice that it seems tobe made up of bundles of small fibres or threads of flesh. With a littlecare you can pick one of the small fibres into fine threads. Now, if youlook at one of these under a microscope you find that it is made ofstill finer fibres, which are much smaller than the threads of aspider's web. One of these smallest threads is called a _muscularfibre_. 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 endis attached to one bone, and the other to another bone. Sometimes oneend is made fast to a bone and the other to the skin or to othermuscles. 

~6. The Tendons. ~--Many of the muscles are not joined to the bonesdirectly, 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 wristof the right hand, and then work the fingers of the right hand, you mayfeel these cords moving underneath the skin. 

~7. What the Muscles Do. ~--With the left hand grasp the right arm justin 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 andharden when they act. 

~8. ~ All the movements of the body are made by means of muscles. When wemove our hands, even when we close the mouth or the eyes, or make a wryface, we use the muscles. We could not speak, laugh, sing, or breathewithout muscles. 

~9. Self-acting Muscles. ~--Did you ever have a fit of sneezing orhiccoughing? If you ever did, very likely you tried hard to stop butcould not. Do you know why one cannot always stop sneezing orhiccoughing when he desires to do so? It is because there are certainmuscles 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 wesneeze or hiccough are of this kind. The arm and the hand do not actunless 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 itwould not act when we were asleep. The same is true of our breathing. Webreathe when we are asleep as well as when we are awake, because thebreathing muscles work even when we do not think about them. 

~10. ~ The stomach, the intestines, the blood-vessels, and many otherorgans within the body have this kind of muscles. The work of theseself-acting muscles is very wonderful indeed. Without it we could notlive a moment. This knowledge should lead us to consider how dependentwe are, each moment of our lives, upon the delicate machinery by whichthe most important work of our bodies is performed, and how particularwe should be to keep it in good order by taking proper care ofourselves. 

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 cordscalled tendons. 

5. Muscular fibres can contract so as to lessen their length. It is inthis 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. Somemuscles, however, act when it is necessary for them to do so, whether wewill that they should act or not, and when we are asleep as well as whenwe are awake. 

CHAPTER XXI. 

HOW TO KEEP THE MUSCLES HEALTHY. 

~1. How to Make the Muscles Strong. ~--With which hand can you lift themore? with the right hand or with the left? Why do you think you canlift more with the right hand than with the left? A blacksmith swings aheavy hammer with his right arm, and that arm becomes very large andstrong. If we wish our muscles to grow large and strong, so that ourbodies will be healthy and vigorous, we must take plenty of exercise. 

~2. Effects of Idleness. ~--If a boy should carry one hand in his pocketall the time, and use only the other hand and arm, the idle arm wouldbecome small and weak, while the other would grow large and strong. Anypart of the body which is not used will after a time become weak. Littleboys and girls who do not take plenty of exercise are likely to be paleand puny. It is important that we should take the proper amount ofexercise every day, just as we take our food and drink every day. 

~3. Healthful Exercise. ~--Some kinds of play, and almost all kinds ofwork which children have to do, are good ways of taking exercise. A verygood kind of exercise for little boys and girls is that found in runningerrands or doing chores about the house. 

~4. Food and Strength. ~--A great part of our food goes to nourish themuscles. Some foods make us strong, while others do not. Plain foods, such as bread, meat, potatoes, and milk, are good for the muscles; butcakes 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 liftingheavy 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 topress hard upon any part of the body. If we do, it will cause themuscles of that part to become weak. If the clothing is worn tight aboutthe waist, great mischief is often done. The lungs cannot expandproperly, the stomach and liver are pressed out of shape, and theinternal organs are crowded out of their proper places. 

~7. Tight Shoes. ~--People are often made very lame from wearing tightshoes. Their muscles cannot act properly, and their feet grow out ofshape. 

~8. ~ In China, it is fashionable for rich ladies to have small feet, andthey tie them up in cloths so that they cannot grow. The foot issqueezed out of shape. Here is a picture of a foot which has beentreated in this way. It does not look much like a human foot, does it? Awoman who has such feet finds it so difficult to walk that she has to becarried about much of the time. Do you not think it is very wrong andfoolish to treat the feet so badly? You will say, "Yes;" but the Chinesewoman thinks it is a great deal worse to lace the clothing tight aboutthe body so as to make the waist small. 

[Illustration: FOOT OF CHINESE WOMAN. ]

~9. Effects of Alcohol upon the Muscles. ~--When an intemperate man takesa glass of strong drink, it makes him feel strong; but when he tries tolift, or to do any kind of hard work, he cannot lift so much nor work sohard as he could have done without the liquor. This is because alcoholpoisons the muscles and makes them weak. 

~10. Effects of Drunkenness. ~--When a man has become addicted to strongdrink, his muscles become partly paralyzed, so that he cannot walk assteadily or speak as readily or as clearly as before. His fingers areclumsy, 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 verydrunk, he is for a time completely paralyzed, so that he cannot walk ormove, and seems almost like a dead man. 

~11. ~ If you had a good horse that had carried you a long way in acarriage, and you wanted to travel farther, what would you do if thehorse were so tired that he kept stopping in the road? Would you let himrest 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 youshould whip him he would act as though he were not tired at all, but doyou think the whip would make him strong, as rest and hay and oatswould?

~12. ~ When a tired man takes alcohol, it acts like a whip; it makesevery part of the body work faster and harder than it ought to work, andthus wastes the man's strength and makes him weaker, although for alittle while his nerves are made stupid, so that he does not know thathe is tired and ought to rest. 

~13. ~ When you grow up to be men and women you will want to have strongmuscles. So you must be careful not to give alcohol a chance to injurethem. If you never taste it in any form you will be sure to suffer noharm from it. 

~14. Effects of Tobacco on the Muscles. ~--Boys who smoke cigars orcigarettes, or who chew tobacco, are not likely to grow up to be strongand healthy men. They do not have plump and rosy cheeks and strongmuscles like other boys. 

~15. ~ The evil effect of tobacco upon boys is now so well known that inmany countries and in some states of this country laws have been madewhich do not allow alcohol or tobacco to be sold or given to boys. InSwitzerland, if a boy is found smoking upon the streets, he is arrestedjust as though he had been caught stealing. And is not this really whata boy does when he smokes? He robs his constitution of its vigor, andallows tobacco to steal away from him the strength he will need when hebecomes a man. 

~16. Tea and Coffee. ~--Strong tea and coffee, while by no means so badas alcohol and tobacco, may make us weak and sick. A person who drinksstrong tea or coffee feels less tired while at work than if he had nottaken it, but he is more tired afterwards. So you see that tea andcoffee are also whips, small whips we might call them, and yet theyreally act in the same way as do other narcotics and stimulants. Theymake a person feel stronger than he really is, and thus he is led to usemore 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 lungsactive, the heart vigorous, and the whole body healthy. 

4. Things we ought not to do: To run or play hard just before or aftereating; to strain our muscles by lifting too heavy weights; to exerciseso violently as to get out of breath; to lie, sit, stand, or walk in acramped position, or awkward manner; to wear the clothing so tight as topress 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 feelstronger. 

7. A boy who uses tobacco will not grow as strong and well as one whodoes 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 atonce say that we think with the head; but we do not think with the wholehead. Some parts of the head we use for other purposes, as the mouth toeat and speak with, and the nose to smell and breathe with. The part wethink with is inside of the skull, safely placed in a little room at thetop and back part of the head. Do you remember the name of this organwhich fills the hollow place inside of the skull? We learned some timeago that it is called the _brain_. It is with the brain that we studyand remember and reason. So the brain is one of the most importantorgans 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 isshut up in the skull; but perhaps you can find the brain of a sheep or acalf at the meat market. The brain of one of these animals looks verynearly like your own. 

~3. The Large Brain and the Small Brain. ~--In examining a brain weshould notice first of all that there are really two brains, a _largebrain_ and a _small brain_. The large brain is in the top and front ofthe skull, and the small one lies beneath the back part of the largerone, If we look again we shall see that each brain is divided in themiddle into a right and a left half. Each half is, in fact, a completebrain, so that we really have two pairs of brains. 

[Illustration: THE BRAIN. ]

~4. Brain Cells. ~--The brain is a curious organ of a grayish coloroutside and white inside. It is soft, almost like jelly, and this is whyit is placed so carefully in a strong, bony box. If we should put alittle piece of the brain under a microscope, we should find that it ismade up of a great number of very small objects called _nerve_ or_brain cells_. In the illustration you can see some of these braincells. 

[Illustration: BRAIN CELLS. ]

~5. The Nerves. ~--Each cell has one or more branches. Some of thebranches are joined to the branches of other cells so as to unite thecells together, just as children take hold of one another's hands. Otherbranches are drawn out very long. 

~6. ~ The long branches are such slender threads that a great number ofthem together would not be as large as a fine silk thread. A great manyof these fine nerve threads are bound up in little bundles which looklike 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 nervescoming to them from the brain. So you see that the brain is not whollyshut up in the skull, because its cells have slender branches runninginto all parts of the body; and thus the brain itself is really in everypart of the body, though we usually speak of it as being entirely in theskull. 

~8. The Spinal Cord. ~--There are a number of small holes in the skullthrough which the nerves pass out, but most of the nerves are bound upin one large bundle and pass out through an opening at the back part ofthe skull and runs downward through a long canal in the backbone. Thisbundle of nerves forms the _spinal cord_. The spinal cord contains cellsalso, like those of the brain. It is really a continuation of the braindown through the backbone. 

[Illustration: BRAIN AND SPINAL CORD. ]

~9. Nerves from the Spinal Cord. ~--The spinal cord gives off branches ofnerves which go to the arms, the chest, the legs, and other parts. Oneof the branches which goes to the hand runs along the back side of thearm, passing over the elbow. If we happen to strike the elbow againstsome sharp object, we sometimes hit this nerve. When we do so, the underside of the arm and the little finger feel very numb and strange. Thisis why you call this part of the elbow the "funny" or "crazy bone. " Thecells of the spinal cord also send out branches to the body and to othercells in the brain. 

~10. How we Feel. ~--If we cut or burn ourselves we suffer pain. Can youtell why it hurts us to prick the flesh with a pin, or to pinch or burnor bruise it? It is because the flesh contains a great manynerve-branches from the brain. When we hurt the skin or the flesh, inany way, these nerves are injured. There are so many of these littlenerves in the flesh and skin that we cannot put the finest needle intothe flesh without hurting some of them. 

~11. The Use of Pain. ~--It is not pleasant for us to have pain, but ifthe nerves gave us no pain when we are hurt we might get our limbsburned 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 takea marble or a pencil in the hand you know what it is by the feeling ofthe 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 tohear, see, taste, and smell, of which we shall learn in another lesson. Besides these we have nerves which tell us whether objects are cold orhot, and heavy or light. Nerves of feeling also tell us when we arehungry, or thirsty, or tired, and when we need more air to breathe. 

~14. Nerves of Work. ~--There are other nerves which are made just likethe nerves of feeling, but which do not feel. These nerves have a verydifferent use. They come from cells in the brain which have charge ofthe different kinds of work done in the body, and they send theirbranches to the parts which do the work; hence we call them _nerves ofwork_. 

~15. ~ One set of cells sends nerves to the heart, and these make it gofast or slow as is necessary. Another sends nerves to the liver, stomach, and other digestive organs, and causes them to do their part inthe digestion of the food. Other cells send branches to the muscles andmake them act when we wish them to do so. Thus you see how very usefulthe brain and nerves are. They keep all the different parts of the bodyworking together in harmony, just like a well-trained army, or a greatnumber of workmen building a block of houses. Without the brain andnerves the body would be just like an army without a commander, or a lotof workmen without an overseer. 

~16. How we Use the Nerves. ~--If you happen to touch your hand to a hotstove, 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 thenerve cells in the brain from which they come that the hand is beingburned. The cells which feel cannot do anything for the hand, but someof their branches run over to another part of the brain, which sendsnerves down to the muscles of the arm. These cells, through their nervebranches, cause the muscles to contract. The cells of feeling ask thecells which have charge of the muscles to make the muscles of the armpull the hand away, which they do very quickly. 

~17. ~ So you see the nerves are very much like telegraph or telephonewires. By means of them the brain finds out all about what is happeningin the body, and sends out its orders to the various organs, which maybe called its servants. 

~18. An Experiment. ~--A man once tried an experiment which seemed verycruel. He took a dove and cut open its skull and took out its largebrain. 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 knowanything. It did not know when it was hungry, and would not eat or drinkunless the food or water was placed in its mouth. If a man gets a blowon his head, so hard as to break his skull, the large brain is oftenhurt so badly that its cells cannot work, and so the man is in the samecondition as the poor dove. He does not know anything. He cannot thinkor talk, and lies as though he were asleep. 

~19. ~ By these and many other facts we know that the large brain is thepart with which we remember, think, and reason. It is the seat of themind. We go to sleep because the large brain is tired and cannot workany longer. We stop thinking when we are sound asleep, but sometimes wedo not sleep soundly, and then the large brain works a little and wedream. 

~20. What the Little Brain Does. ~--The little brain[B] thinks too, butit does not do the same kind of thinking as the large brain. We may useour arms and legs and many other parts when we wish to do so; and if wedo not care to use them we may allow them to remain quiet. This is notthe case with some other organs. It is necessary, for example, that theheart, the lungs, and many other organs of the body should keep at workall the time. If the large brain had to attend to all of thesedifferent kinds of work besides thinking about what we see, hear, andread, 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 brainsometimes falls asleep. So the large brain lets the little brain do thekinds of work which have to be attended to all the time, and the littlebrain keeps steadily at work when we are asleep as well as when we areawake. 

~21. What the Spinal Cord Does. ~--If you tickle a person's foot when heis asleep, he will pull it up just as he would if he were awake, onlynot quite so quickly. What do you suppose makes the muscles of the legcontract when the brain is asleep and does not know that the foot isbeing tickled? And here is another curious fact. When you were coming toschool this morning you did not have to think about every step you took. Perhaps you were talking or looking over your lessons; but your legswalked 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 thinkevery time we step, and the little brain has work enough to do in takingcare of the heart and lungs and other organs, without keeping watch ofthe feet when we are asleep, so as to pull them up if some mischievousperson tickles them. So Nature puts a few nerve cells in the spinal cordwhich can do a certain easy kind of thinking. When we do things over andover a great many times, these cells, after a time, learn to do themwithout the help of the large brain. This is the way a piano-playerbecomes so expert. He does not have to think all the time where eachfinger 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 themalmost 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 makingtwo pairs of brains. 

5. The brain is largely made up of very small objects called nerve orbrain 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 passout from the brain to the rest of the body through a number of openingsin the skull. 

8. Most of the nerve branches pass out through a large opening at theback of the skull, in one large bundle called the spinal cord. 

9. The spinal cord runs down through a canal in the backbone, and allalong 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 whenwe 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 thisbecause if a nerve is cut in two, we may hurt the part to which it goeswithout giving any pain. 

12. We have different kinds of nerves of feeling. 

13. There are other nerves besides those of feeling. These are nerves ofwork. 

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 oract. 

15. The brain and nerves control the body and make all the differentparts 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 ortelegraph wires. 

17. With the large brain we remember, think, and reason. 

18. The little brain does the simple kind of thinking, by means of whichthe heart, lungs, and other vital organs are kept at work even when weare asleep. 

19. The spinal cord does a still more simple kind of work. It enables usto walk and to do other familiar acts without using the large brain tothink 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 goodfor 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 acabbage or a potato knows. If the brain or nerves are sick, they cannotwork well, and so are not worth as much as when they are healthy. 

~2. The Brain Sympathizes with Other Organs. ~--Did you ever have aheadache? 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 veryimportant that we should keep our brain and nerves healthy, and to dothis we must take good care of the stomach and all other organs, becausethe brain sympathizes with them when they are sick. 

~3. We must have Pure Air. ~--How do you feel when the school-room is toowarm and close? Do you not feel dull and sleepy and so stupid that youcan hardly study? This is because the brain needs good, pure blood toenable it to work well. So we must always be careful to have plenty ofpure air to breathe. 

~4. We should Exercise the Brain. ~--What do we do when we want tostrengthen our muscles? We make them work hard every day, do we not? Theexercise makes them grow large and strong. It is just the same with ourbrains. If we study hard and learn our lessons well, then our brainsgrow strong, and study becomes easy. But if we only half study, and donot learn our lessons perfectly, then the study does not do our brainsvery much good. 

~5. We should Take Muscular Exercise. ~--When you get tired of study, anhour's play, or exercise of some sort, rests you and makes you feelbrighter, so that you can learn more easily. This is because exercise isnecessary to make the blood circulate well. It will then carry out theworn-out particles and supply the brain and nerves with fresh, pureblood. So the same exercise which makes our muscles strong makes ourbrains 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 notwell for children to eat freely of meat, as it is very stimulating andlikely to excite the brain and make the nerves irritable. Mustard, pepper, and all hot sauces and spices have a tendency to injure thebrain and nerves. 

~7. We should Allow the Brain to Rest at the Proper Time. ~--When we aretired and sleepy we cannot think well, and cannot remember what we learnif we try to study. If we have plenty of sleep, free from bad orexciting dreams, we awake in the morning rested and refreshed, becausewhile we have been asleep Nature has put the brain and nerves in goodrepair for us. We ought not to stay up late at night. We should not eatlate or hearty suppers, as this will prevent our sleeping well. 

~8. We Ought Not to Allow Ourselves to Become Angry. ~--When a personflies into a passion he does his brain and nerves great harm. It isreally dangerous to get angry. Persons have dropped dead instantly in afit 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 toswear, or to use slang phrases, the brain after a while will make himswear or use bad words before he thinks. In a similar manner other badhabits are acquired. 

SUMMARY. 

1. A person without a brain or nerves would be of no more account than avegetable. 

2. When the brain or nerves are sick they cannot perform their dutiesproperly. 

3. To keep the brain and nerves in good health, we must take good careof the stomach and all other important organs of the body. 

4. There are many things which we may do to keep the brain and nervesstrong and well. 

5. The brain needs pure blood, and so we must be careful to breathe pureair. 

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 remembereverything. 

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 theblood to circulate. 

10. Plenty of wholesome and simple food is necessary to keep the brainand nerves in good health. Spices, condiments, and rich foods in generalare 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, asthey 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 ina 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 aquarrel with some one. 

~2. ~ What made the man drunk? You say whiskey, but it may have beenwine, or beer, or hard cider that he drank. Anything that containsalcohol will make a man drunk, for it is the alcohol which does all themischief. 

~3. The Whiskey Flush. ~--You can almost always tell when a man has beendrinking, even when he has not taken enough to make him drunk. You knowby his flushed face and red eyes. When a man's face blushes from the useof alcohol, his whole body blushes at the same time. His muscles, hislungs, 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 alittle, the extra amount of blood in the brain makes him think and talkmore lively, and he is very jolly and gay. This makes many people thinkthat alcohol does them good. But if we notice what a man says when he isexcited by alcohol, we shall find that his remarks are often silly andreckless. He says very unwise and foolish things, for which he feelssorry when he becomes sober. 

~5. Alcohol Paralyzes. ~--How does a drunken man walk? Let us see why hestaggers. When a man takes a certain amount of alcohol his small brainand spinal cord become partly paralyzed, so that they cannot do theirduty well; and so, when he tries to walk he reels and stumbles along, often falling down, and sometimes hurting himself very much. The fact isthat the alcohol has put his spinal cord and small brain to sleep sothat he cannot make his legs do what he wants them to do. Now, if stillmore alcohol is taken the whole brain becomes paralyzed, and then theman is so nearly dead that we say he is "dead drunk. " It is exceedinglydangerous to become dead drunk, as the brain may be so completelyparalyzed that it will not recover. 

~6. ~ A small amount of alcohol does not make a man dead drunk, but itpoisons and paralyzes his brain and nerves just according to thequantity 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 paralyzesthem so that they cannot feel or taste. When taken into the stomach ithas 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 andbenumbs 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 towarn 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 andfreezes to death. A tired man takes his glass of grog and feels restedand strong, though he is really weaker than before. A poor man getsdrunk and feels so rich that he spends what little money he has. Thealcohol paralyzes his judgment and steals away his good sense. Thusalcohol is always a deceiver. 

~9. Delirium Tremens. ~ (De-lir´-i-um Tre´-mens. )--When a man takesstrong liquors regularly he very soon injures his brain and nerves sothat they do not get quiet, as they should, at night, and he does notsleep well. He has frightful dreams. He sees all sorts of wild animalsand horrid shapes in his dreams. Perhaps you have sometimes had suchdreams from eating late suppers or indigestible food. 

~10. ~ Did you ever have a dream when you were awake? If a man drinks agreat deal he is likely to have a terrible disease known as _deliriumtremens_, in which he sees the same frightful things when he is wideawake that he dreams about when he is asleep. This is one of theterrible effects of alcohol upon the brain and nerves. 

~11. Alcohol Paralysis. ~--You have seen how a drunken man staggers whenhe walks. Did you ever see a man who walked just as though he were drunkwhen he was really sober? This is because a part of the brain or spinalcord has been permanently injured or paralyzed. Alcohol is not the onlycause of this disease, and so you must not think every person whostaggers is or has been a drunkard; but alcohol is a very frequent causeof paralysis. 

~12. Effects of Alcohol upon the Mind and Character. ~--When a man isunder the influence of alcohol is his character good or bad? Is a manlikely 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 beendrunk a great many times they often behave badly all the time. A greatmany of the men who are shut up in prisons would not have been sentthere if they had never learned to drink. 

~13. A Legacy. ~--Do you know what a legacy is? If your father should dieand 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 wouldbe a legacy. When a person gets anything in this way from a parent wesay that he inherits it. 

~14. ~ We inherit a great many things besides houses and lands and otherkinds of property. For instance, perhaps you remember hearing some onesay that you have eyes and hair the same color as your mother's, andthat your nose and chin are like your father's. So you have inheritedthe color of your hair and eyes from your mother and the shape of yourchin and nose from your father. 

~15. The Alcohol Legacy. ~--The inside of a boy's head is just as muchlike his parents' as the outside of it. In other words, we inherit ourbrains just as we do our faces. So, if a man spoils his brain withalcohol and gets an alcohol appetite, his children will be likely tohave unhealthy brains and an appetite for alcohol also, and may becomedrunkards. Is not that a dreadful kind of legacy to inherit?

~16. ~ A child that has no mind is called an idiot. Such a child cannottalk, or read, or sing, and does not know enough to take proper care ofitself. This is one of the bad legacies which drunken parents sometimesleave to their children. 

~17. Effects of Tobacco on the Brain and Nerves. ~--The effects oftobacco upon the brain and nerves are much the same as those of alcohol. Tobacco, like alcohol, is a narcotic. It benumbs and paralyzes thenerves, and it is by this means that it obtains such an influence overthose who use it. 

~18. ~ The hand of a man or boy who uses tobacco often becomes sounsteady that he can scarcely write. Do you know what makes it sounsteady? It is because the cells which send nerves to the muscles ofthe hand are diseased. When a person has a trembling hand you say he isnervous. If you feel his pulse you will find that it does not beatsteadily and regularly as it ought to do. The heart is nervous andtrembles just the same as the muscles do. This shows that the tobaccohas poisoned the cells in the brain which regulate the heart. 

~19. ~ Wise physicians will tell you that one reason why tobacco is badfor 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 notallowed to use tobacco on account of its bad effects upon the mind. InFrance the use of tobacco is forbidden to all students in the publicschools. 

~21. Tobacco Leads to Vice. ~--Boys who use tobacco are more liable toget into company with boys who have other bad habits, and so are apt tobecome bad in many other ways. The use of tobacco often makes men wantstrong drink, and thus leads to drunkenness. If you wish to grow up witha steady hand, a strong heart, and a good character you will never touchtobacco. 

~22. Effects of Tea and Coffee on the Nerves. ~--People who use strongtea and coffee are often inclined to be nervous. This shows that strongtea and coffee, like alcohol and tobacco, are very injurious to thenerves. 

~23. Opium, Chloral, etc. ~--There are several drugs which are given byphysicians to relieve pain or to produce sleep. They are sometimeshelpful, but their use is very dangerous. Opium and chloral belong tothis class of medicines. The danger is that, after a person has used themedicine a little while, he will continue to use it. If a person takes apoisonous drug every time he has a little pain, he will soon form thehabit of using it, and may never break it off. There are many thousandsof people who use opium all the time, and they are very much injured byit in mind and body. The mind becomes dull and stupid and the body weakand feeble. No medicine of this sort should ever be taken unlessprescribed by a physician. 

SUMMARY. 

1. In order to be well and useful we must keep the brain and nerveshealthy. 

2. To keep the brain healthy we need plenty of pure air to breathe;proper exercise of the brain by study; sufficient exercise of themuscles in play and work; plenty of good food to make pure blood; aproper amount of rest and sleep. 

3. There are several things we ought not to do. We should not read orstudy too much. We should not allow ourselves to become excited orangry. 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 whenhe is weak; warm when he is cold; rich when he is poor; well when he issick. 

6. Alcohol makes men wicked. Most men who commit crimes are men who useliquor. 

7. The effects of tobacco upon the brain and nerves are much the same asthose 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 useof 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 theyare very different from each other. They also differ from the generalsense 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 aspecial set of nerves and also special cells in the brain which havecharge 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 smellin the brain just as we feel in the brain. The eyes, ears, nose, andother organs of the special senses are the instruments by means of whichthe brain sees, hears, smells, etc. 

~3. Sound and the Vibrations which it Causes. ~--All sounds are made byjars or vibrations of objects. Sounds cause objects to vibrate ortremble. A loud sound sometimes jars a whole house, while other soundsare so gentle and soft that we cannot feel them in the same way that wefeel loud sounds. But Nature has made for us an ingenious organ by meansof which we can feel these very fine vibrations as well as loud ones. Wecall this organ the _ear_. 

~4. The Ear. ~--The part of the ear which we can see is shaped somewhatlike a trumpet. The small opening near the middle of the ear leads intoa _canal_ or tube which extends into the head about an inch. At theinner 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 isstretched a thin membrane like the head of a drum. The ear-drum is alsocalled the _middle ear_. 

[Illustration: THE EAR. ]

~5. Bones of the Ear. ~--Within the drum of the ear there are threecurious little bones which are joined together so as to make a completechain, reaching from the drum-head to the other side of the drum. Thelast bone fits into a little hole which leads into another curiouschamber. This chamber, which is called the _inner ear_, is filled withfluid, and in this fluid the nerve of hearing is spread out. A part ofthe 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 woodenpole. Have some one listen with the ear placed close against the otherend of the pole. He will tell you that he hears the scratching of thepin very plainly. This is because the scratching jars the ear andespecially the drum-head, which vibrates just as the head of a drum doeswhen it is beaten with a drum-stick. When the drum-head vibrates itmoves the bones of the ear, and these carry the vibration to the nervesof 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. Therest of the inner ear hears ordinary sounds or noises. 

~7. How to Keep the Ears Healthy. ~--The ears are very delicate organsand must be carefully treated. The following things about the care ofthe ears should never be forgotten:

(1. ) Never use a pin, toothpick, or any other sharp instrument to cleanout the ear. There is great danger that the drum-head will be torn, andthus the hearing will be injured. Neither is it ever necessary to use anear-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 blowdirectly into it. 

(3. ) If anything accidentally gets into the ear, do not work at it, buthold the head over to one side while water is made to run in from asyringe. If an insect has gone into the ear, pour in a little oil. Thiswill kill the insect or make it come out. 

(4. ) Never shout into another person's ear. The ear may be greatlyinjured in this way. 

(5. ) Boxing or pulling the ears is likely to produce deafness, and oughtnever to be done. 

~8. The Eye. ~--The eye is one of the most wonderful organs in the wholebody. 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 othersenses can tell us nothing about. It also enables us to read. Let uslearn how this wonderful organ is made. 

~9. The Eyeball. ~--Looking at the eye, we see first a round part whichrolls in different directions. This is the _eyeball_. We see only thefront side of the eyeball as it fits into a hollow in the skull. Beingthus 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 likejelly. It is so clear that the light can shine through it just as easilyas it can shine through water. 

~10. The Pupil. ~--If you look sharply at the eyeball you will see asmall black hole just in the centre. This is a little window which letsthe light into the inside of the eyeball. We call this the _pupil_. Justaround the pupil is a colored ring which gives the eye its color. We saya person has blue or brown or gray eyes according as this ring is blueor brown or gray. This colored ring is a kind of curtain for the windowof the eye. 

~11. ~ If you observe the pupil closely, you will see that it issometimes larger and sometimes smaller. If you look at the light thepupil is small; if you turn away from the light the pupil grows largerat once. This is because the curtain closes when in a bright light andopens in the darkness. It does this of itself without our thinking aboutit. In this way the eye is protected from too strong a light, whichwould do it great harm. 

~12. ~ If you look a little sidewise at the eyeball, you will see thatthe curtain has something in front of it which is clear as glass. It isabout the shape of a watch crystal, only very much smaller. This is tothe eye what the glass is to the windows of a house. It closes theopening 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, firmmembrane 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 itby this name, but you are familiar with the spectacles which peoplesometimes wear to help their eyes. The glasses in the spectacle framesare called lenses. Well, there is something in the eye almost exactlylike one of these lenses, only smaller. It is also called a _lens_. Ifsome one will get the eye of an ox for you, you can cut it open and findthis part. The lens is placed in the eyeball just behind the pupil. (Seepicture. )

[Illustration: THE INSIDE OF THE EYE. ]

~15. The Nerves of Sight. ~--But a person might have an eyeball with allthe parts we have learned about and yet not be able to see. Can you tellwhat more is needed? There must be a nerve. This nerve comes from somelittle nerve cells in the brain and enters the eyeball at the back ofthe eye; there it is spread out on the inside of the black lining of thewhite of the eye. 

~16. The Eyelids. ~--Now we know all that it is necessary for us to learnabout the eyeball, so let us notice some other parts about the eye. First there are the eyelids. They are little folds of skin fringed withhairs, which we can shut up so as to cover the eyeball and keep out thelight when we want to sleep or when we are in danger of getting dust orsmoke into the eye. The hairs placed along the edge of the lids help tokeep the dust out when the eyes are open. 

~17. The Eyebrows. ~--The row of hairs placed above the eye is called theeyebrow. Like the eyelids, the eyebrows catch some substances whichmight fall into the eye, and they also serve to turn off theperspiration and keep it out of the eyes. 

~18. The Tear Gland. ~--Do you know where the tears come from? There is alittle gland snugly placed away in the socket of the eye just above theeyeball, which makes tears in the same way that the salivary glands makesaliva. It is called the _tear gland_. The gland usually makes justenough tears to keep the eye moist. There are times when it makes morethan enough, as when something gets into the eye, or when we suffer painor feel unhappy. Then the tears are carried off by means of a littletube 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 throughthis tube, they pass over the edge of the lower eyelid and flow down thecheek. 

~19. Muscles of the Eyes. ~--By means of little muscles which arefastened to the eyeball, we are able to turn the eye in almost everydirection. 

~20. How we See. ~--Now we want to know how we see with the eye. This isnot very easy to understand, but we can learn something about it. Let usmake a little experiment. Here is a glass lens. If we hold it before awindow and place a piece of smooth white paper behind it, we can see apicture of the houses and trees and fences, and other thingsout-of-doors. The picture made by the lens looks exactly like the viewout-of-doors, except that it is upside down. This is one of the curiousthings that a lens does. The lens of the eye acts just like a glasslens. It makes a picture of everything we see, upon the ends of thenerves of sight which are spread out at the back of the eyeball. Thenerves of sight tell their nerves in the brain about the picture, justas the nerves of feeling tell their cells when they are touched with apin; and this is how we see. 

~21. ~ Did you ever look through a spyglass or an opera-glass? If so, youknow you must make the tube longer or shorter according as you look atthings near by or far away. The eye also has to be changed a littlewhen we look from near to distant objects. Look out of the window at atree a long way off. Now place a lead pencil between the eyes and thetree. You can scarcely see the pencil while you look sharply at thetree, 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 neededto enable us to see objects close by as well as those which are fartheraway. 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, asin reading. Children should not try to wear old persons' glasses, asthis is likely to injure their eyes. 

~23. How to Keep the Eyes Healthy. ~--(1. ) Never continue the use of theeyes at fine work, such as reading or fancy-work, after they have becomevery tired. 

(2. ) Do not try to read or to use the eyes with a poor light--in thetwilight, for instance, before the gas or lamps are lighted. 

(3. ) In reading or studying, do not sit with the light from either alamp or a window shining directly upon the face. Have the light comefrom behind and shine over the left shoulder if possible. 

(4. ) Never expose the eyes to a sudden, bright light by looking at thesun or at a lamp on first awaking in the morning, or by passing quicklyfrom a dark room into a lighted one. 

(5. ) Do not read when lying down, or when riding on a street car orrailway train. 

(6. ) If any object gets into the eye have it removed as soon aspossible. 

(7. ) A great many persons hurt their eyes by using various kinds ofeye-washes. Never use anything of this kind unless told to do so by agood physician. 

~24. How we Smell. ~--If we wish to smell anything very strongly, wesniff or suddenly draw the air up through the nose. We do this to bringmore air to the nerves of smell, which are placed at the upper part ofthe inside of the nose. 

[Illustration: INSIDE OF THE NOSE. ]

~25. ~ Smelling is a sort of feeling. The nerves of smell are sosensitive that they can discover things in the air which we cannot tasteor see. An Indian uses his sense of smell to tell him whether thingsare good to eat or not. He knows that things which have a pleasant smellare 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 andmany lower animals, and hence we are not able to smell so acutely. Manypersons lose the sense of smell altogether, from neglecting colds in thehead. 

~26. How we Taste. ~--The tongue and the palate have very delicate nervesby means of which we taste. We cannot taste with the whole of thetongue. 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 tellus whether different substances are healthful or injurious. Things whichare poisonous and likely to make us sick almost always have anunpleasant taste as well as an unpleasant odor. Things which have apleasant taste are usually harmless. 

~28. Bad Tastes. ~--People sometimes learn to like things which have avery unpleasant taste. Pepper, mustard, pepper-sauce, and other hotsauces, alcohol, and tobacco are harmful substances of this sort. Whenused freely they injure the sense of taste so that it cannot detect andenjoy fine and delicate flavors. These substances, as we have elsewherelearned, also do the stomach harm and injure the nerves and other partsof the body. 

~29. The Sense of Touch. ~--If you put your hand upon an object you cantell whether it is hard or soft, smooth or rough, and can learn whetherit is round or square, or of some other shape. You are able to do thisby means of the nerves of touch, which are found in the skin in allparts of the body. If you wished to know how an object feels, would youtouch 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 ofthe fingers. You can feel objects better with the ends of the fingersbecause there are more nerves of touch in the part of the skin coveringthe 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 thanin any other part. This is because it is necessary to use the sense oftouch in the tongue to assist the sense of taste in finding out whetherthings are good to eat or not. The sense of touch is also very useful tous in many other ways. We hardly know how useful it really is until weare deprived of some of our other senses, as sight or hearing. In ablind man the sense of touch often becomes surprisingly acute. 

~31. Effects of Alcohol and Tobacco on the Special Senses. ~--All thespecial senses--hearing, seeing, smelling, tasting, feeling--depend uponthe brain and nerves. Whatever does harm to the brain and nerves mustinjure the special senses also. We have learned how alcohol and tobacco, and all other narcotics and stimulants, injure and sometimes destroy thebrain cells and their nerve branches, and so we can understand that aperson who uses these poisonous substances will, by so doing, injure thedelicate 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 arefrequently injured by the use of tobacco. Smoking cigarettes andsnuff-taking destroy the sense of smell. The poison of the tobaccoparalyzes the nerves of taste so that they cannot detect flavors. Tea-tasters and other persons who need to have a delicate sense of tastedo not use either alcohol or tobacco. 

SUMMARY. 

1. We have five special senses--hearing, seeing, smelling, tasting, andfeeling. 

2. The ear is the organ of hearing, and has three parts, called theexternal ear, the middle ear, and the inner ear. The inner ear containsthe 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 thevibration from the drum-head to the nerve of hearing. 

5. To keep the ear healthy we must avoid meddling with it or puttingthings into it. 

6. The eye is the organ of sight. The chief parts of the eye are theeyeball, 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 thenerve of sight, at the back part of the eyeball. 

11. To keep the eyes healthy we should be careful not to tax them longat 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 ofthe 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, butsmell or feel. 

16. Objects which have a pleasant taste are usually healthful, whilethose which have a bad taste are usually harmful. 

17. Pepper, mustard, etc. , as well as alcohol and tobacco, have anunpleasant taste, and are not healthful. If we use them we shall injurethe 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 theends 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 fromwater and other substances by _distillation_. We will now learn a fewmore things about alcohol. 

~2. Alcohol Burns. ~--If alcohol is placed in a lamp, it will burn muchlike kerosene oil. Indeed, it does not need a lamp to help it burn asdoes oil. If a few drops of alcohol are placed upon a plate, it may belighted with a match, and will burn with a pale blue flame. Thus you seethat alcohol is a sort of burning fluid. 

~3. ~ The vapor of alcohol will burn also, and under some circumstancesit will explode. On this account it is better not to try any experimentswith it unless some older person is close by to direct you, so that noharm may be done. Alcohol is really a dangerous substance even though wedo not take it as a drink. 

~4. An Interesting Experiment. ~--We have told you that all fermenteddrinks contain alcohol. You will remember that wine, beer, ale, andcider are fermented drinks. We know that these drinks contain alcoholbecause the chemist can separate the alcohol from the water and othersubstances, and thus learn just how much alcohol each contains. 

~5. ~ If we should remove all the alcohol from wine, no one would care todrink it. The same is true of beer and cider. It is very easy to removethe alcohol by the simple process of heating. This is the way thechemist separates it. The heat drives the alcohol off with the steam. Ifthe heating is continued long enough, all the alcohol will be drivenoff. The Chinaman boils his wine before drinking it. Perhaps this is onereason why Chinamen are so seldom found drunken. 

~6. ~ By a simple experiment which your parents or your teacher canperform for you, it can be readily proven that different fermenteddrinks contain alcohol, and also that the alcohol may be driven off byheat. Place a basin half full of water upon the stove where it will soonboil. Put into a glass bottle enough beer or cider so that when thebottle stands up in the basin the liquid in the bottle will be at aboutthe same height as the water in the basin. Now place in the neck of thebottle a closely fitting cork in which there has been inserted a pieceof the stem of a clay pipe or a small glass tube. Place the bottle inthe basin. Watch carefully until the liquid in the bottle begins toboil. Now apply a lighted match to the end of the pipe-stem or glasstube. Perhaps you will observe nothing at first, but continue placingthe match to the pipe-stem, and pretty soon you will notice a littleblue flame burning at the end of the stem. It will go out often, but youcan light it again. This is proof that alcohol is escaping from theliquid in the bottle. After the liquid has been boiling for some time, the flame goes out, and cannot be re-lighted, because the alcohol hasbeen all driven off. 

[Illustration: Alcohol experiment. ]

~7. The Alcohol Breath. ~--You have doubtless heard that a person who isunder the influence of liquor may be known by his breath. His breathsmells of alcohol. This is because his lungs are trying to remove thealcohol from his blood as fast as possible, so as to prevent injury tothe blood corpuscles and the tissues of the body. It is the vapor ofalcohol mixed with his breath that causes the odor. 

~8. ~ You may have heard that sometimes men take such quantities ofliquor that the breath becomes strong with the vapor of alcohol andtakes fire when a light is brought near the mouth. These stories areprobably not true, although it sometimes happens that persons becomediseased in such a way that the breath will take fire if it comes incontact 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 wouldlike to find out for themselves that alcohol is really made byfermentation. This may be done by an easy experiment. You know thatyeast will cause bread to "rise" or ferment. As we have elsewherelearned, a little alcohol is formed in the fermentation of bread, but isdriven off by the heat of the oven in baking, so that we do not take anyof it into our stomachs when we eat the bread. If we place a littlebaker's yeast in sweetened water, it will cause it to ferment andproduce alcohol. To make alcohol, all we have to do is to place a littleyeast and some sweetened water in a bottle and put it away in a warmplace for a few hours until it has had time to ferment. You will knowwhen fermentation has taken place by the great number of small bubbleswhich appear. When the liquid has fermented, you may prove that alcoholis present by means of the same experiment by which you found thealcohol in cider or wine. (See page 160. )

~10. ~ Alcohol is made from the sweet juices of fruits by simply allowingthem to ferment. Wine, as you know, is fermented grape juice. Cider isfermented apple juice. The strong alcoholic liquor obtained bydistilling wine, cider, or any kind of fermented fruit juice, is knownas brandy. 

~11. How Beer is Made. ~--Beer is made from grain of some sort. The grainis first moistened and kept in a warm place for a few days until itbegins to sprout. The young plant needs sugar for its food; and so whilethe grain is sprouting, the starch in the grain is changed into sugar bya curious kind of digestion. This, as you will remember, is the way inwhich the saliva acts upon starch. So far no very great harm has beendone, only sprouted grain, though very sweet, is not so good to eat asgrain which has not sprouted. Nature intends the sugar to be used asfood for the little sproutlet; but the brewer wants it for anotherpurpose, and he stops the growth of the plant by drying the grain in ahot room. 

~12. ~ The next thing the brewer does is to grind the sprouted grain andsoak it in water. The water dissolves out the sugar. Next he adds yeastto the sweet liquor and allows it to ferment, thus converting the sugarinto 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 liquorobtained is then called gin. In the West Indies, on the great sugarplantations, large quantities of liquor are made from the skimmings andcleanings of the vessels in which the sweet juice of the sugar-cane isboiled 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 notproduced by plants in the same way that food is, but that it is theresult of a sort of decay. In making alcohol, good food is destroyed andmade into a substance which is not fit for food, and which produces agreat amount of sickness and destroys many lives. Do you not think it apity that such great quantities of good corn and other grains should bewasted in this way when they might be employed for a useful purpose?

~15. The Alcohol Family. ~--Scientists tell us that there are severaldifferent kinds of alcohol. Naphtha is a strong-smelling liquidsometimes 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 verymuch 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 personvery drunk. Fusel-oil is found in bad whiskey. (All whiskey is bad, butsome kinds are worse than others. ) This is why such whiskey makes men sofuriously drunk. It also causes speedy death in those who use itfrequently. There are still other kinds of alcohol, some of which areeven worse than fusel-oil. So you see this is a very bad family. 

~17. ~ Like most other bad families, this alcohol family has many badrelations. You have heard of carbolic acid, a powerful poison. This isone of the relatives of the alcohol family. Creosote is anotherpoisonous substance closely related to alcohol. Ether and chloroform, bywhich people are made insensible during surgical operations, are alsorelatives of alcohol. They are, in fact, made from alcohol. Thesesubstances, although really useful, are very poisonous and dangerous. Doyou not think it will be very wise and prudent for you to have nothingto do with alcohol in any form, even wine, beer, or cider, since itbelongs to such a bad family and has so many bad relations?

~18. ~ Some persons think that they will suffer no harm if they take onlywine or beer, or perhaps hard cider. This is a great mistake. A personmay 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 fondof stronger liquors. A great many men who have died drunkards began withcider. Cider begins to ferment within a day or two after it is made, andbecomes stronger in alcohol all the time for many months. 

~19. "Bitters. "~--There are other liquids not called "drinks" whichcontain alcohol. "Bitters" usually contain more alcohol than is found inale or wine, and sometimes more than in the strongest whiskey. "Jamaicaginger" is almost pure alcohol. Hence, it is often as harmful for aperson to use these medicines freely as to use alcoholic liquors in anyother 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 makeit safe to use even pure liquor. Alcohol is itself more harmful than theother drugs usually added in adulteration. It is important that youshould know this, for many people think they will not suffer much harmfrom the use of alcohol if they are careful to obtain pure liquors. 

~21. Some Experiments. ~--How many of you remember what you have learnedin previous lessons about the poisonous effects of alcohol? Do peopleever die at once from its effects? Only a short time ago a man made abet that he could take five drinks of whiskey in five seconds. Hedropped dead when he had swallowed the fourth glass. No one eversuffered such an effect from taking water or milk or any other good foodor drink. 

~22. ~ A man once made an experiment by mistake. He was carrying somealcohol across a lawn. He accidentally spilled some upon the grass. Thenext day he found the grass as dead and brown as though it had beenscorched 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 upunder a glass jar where there was a tea-spoonful of alcohol. Thealcohol was in a dish by itself, so it did not touch the plant; but thevapor of the alcohol mixed with the air in the jar so that the plant hadto breathe it. In less than half an hour he took the plant out. Itsleaves were faded and somewhat shrivelled. The next morning it appearedto be dead. Do you suppose the odor of milk or meat, or of any goodfood, would affect a plant like that? Animals shut up with alcohol diein just the same way. 

~24. A Drunken Plant. ~--How many of you remember about a curious plantthat catches flies? Do you remember its name? What does the Venus'sfly-trap do with the flies after it catches them? Do you say that iteats them? Really this is what it does, for it dissolves and absorbsthem. In other words, it digests them. This is just what our stomachs doto the food we eat. 

~25. ~ A few years ago Mr. Darwin thought that he would see what effectalcohol would have upon the digestion of a plant. So he put afly-catching plant in a jar with some alcohol for just five minutes. Thealcohol did not touch the plant, because the jar was only wet with thealcohol on the inside. When he took the plant out, he found that itcould not catch flies, and that its digestion was spoiled so that itcould not even digest very tender bits of meat which were placed on itsleaves. 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 etherand chloroform, and also by nicotine, the poisonous oil of tobacco. Sugar, milk, and other foods had no such effect. This does not look muchas though alcohol would help digestion; does it?

~27. Effects of Alcohol on Digestion. ~--Dr. Roberts, a very eminentEnglish scientist, made many experiments, a few years ago, to ascertainpositively about the effect of alcohol upon digestion. He concluded thatalcohol, even in small doses, delays digestion. This is quite contraryto the belief of very many people, who suppose that wine, cider, orstronger liquors aid digestion. The use of alcohol in the form of beeror other alcoholic drinks is often a cause of serious disease of thestomach and other digestive organs. 

~28. Effects of Alcohol on Animal Heat. ~--A large part of the food weeat is used in keeping our bodies warm. Most of the starch, sugar, andfat in our food serves the body as a sort of fuel. It is by this meansthat the body is kept always at about the same temperature, which isjust a little less than one hundred degrees. This is why we need morefood in very cold weather than in very warm weather. 

~29. ~ When a person takes alcohol, it is found that instead of beingmade warmer by it, he is not so warm as before. He feels warmer, but ifhis temperature be ascertained by means of a thermometer placed in hismouth, it is found that he is really colder. The more alcohol a persontakes the colder he becomes. If alcohol were good food would we expectthis to be the case? It is probably true that the alcohol does make alittle heat, but at the same time it causes us to lose much more heatthan 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 iscooled more rapidly than the blood in the interior of the body. Theeffect of alcohol is to cause the blood-vessels of the outside of thebody to become much enlarged. This is why the face becomes flushed. Alarger amount of warm blood is brought from the inside of the body tothe outside, where it is cooled very rapidly; and thus the body losesheat, instead of gaining it, under the influence of alcohol. This is nottrue of any proper food substance. 

~30. Alcohol in the Polar Regions. ~--Experience teaches the same thingas science respecting the effect of alcohol. Captain Ross, Dr. Kane, Captain Parry, Captain Hall, Lieutenant Greely, and many other famousexplorers who have spent long months amid the ice and snow and intensecold of the countries near the North Pole, all say that alcohol does notwarm 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 noArctic explorer at the present time could be induced to use it. TheHudson Bay Company do not allow the men who work for them to use anykind of alcoholic liquors. Alcohol is a great deceiver, is it not? Itmakes a man think he is warmer, when he is really colder. Many men arefrozen to death while drunk. 

~31. Alcohol in Hot Regions. ~--Bruce, Livingstone, and Stanley, and allgreat African travellers, condemn the use of alcohol in that hot countryas well as elsewhere. The Yuma Indians, who live in Arizona and NewMexico, where the weather is sometimes much hotter than we ever know ithere, have made a law of their own against the use of liquor. If one ofthe tribe becomes drunk, he is severely punished. This law they havemade because of the evil effects of liquor which they noticed among themembers of their tribe who used to become intoxicated. Do you not thinkthat a very wise thing for Indians to do?

~32. Sunstroke. ~--Do you know what sunstroke is? If you do not, yourparents or teacher will tell yow that persons exposed to the heat of thesun on a hot summer day are sometimes overcome by it. They become weak, giddy, or insensible, and not infrequently die. Scores of people aresometimes stricken down in a single day in some of our large cities. Itmay occur to you that if alcohol cools the body, it would be a goodthing 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 aremuch more liable to sunstroke than others. This is on account of thepoisonous effects of the alcohol upon the nerves. No doctor would thinkof giving alcohol in any form to a man suffering with sunstroke. 

~33. Effects of Alcohol upon the Tissues. ~--Here are two interestingexperiments which your teacher or parents can make for you. 

_Experiment 1. _ Place a piece of tender beefsteak in a saucer and coverit with alcohol. Put it away over night. In the morning the beefsteakwill be found to be shrunken, dried, and almost as tough as a piece ofleather. This shows the effect of alcohol upon the tissues, which areessentially like those of lower animals. 

_Experiment 2. _ Break an egg into a half glassful of alcohol. Stir theegg and alcohol together for a few minutes. Soon you will see that theegg begins to harden and look just as though it had been boiled. 

~34. ~ This is the effect of strong alcohol. The alcohol of alcoholicdrinks has water and other things mixed with it, so that it does not actso quickly nor so severely as pure alcohol; but the effect isessentially the same in character. It is partly in this way that thebrain, nerves, muscles, and other tissues of drinking men and womenbecome diseased. 

Eminent physicians tell us that a large share of the unfortunate personswho are shut up in insane asylums are brought there by alcohol. Is itnot a dreadful thing that one's mind should be thus ruined by a uselessand harmful practice?

SUMMARY. 

1. Alcohol is produced by fermentation, and obtained by distillation. Itwill 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 byboiling. 

4. Brandy is distilled from fermented fruit juice, whiskey and gin frombeer or fermented grains, rum from fermented molasses. 

5. Alcohol is the result of a sort of decay, and much good food isdestroyed in producing it. 

6. Besides ordinary alcohol, there are several other kinds. Naphtha andfusel-oil are alcohols. 

7. All the members of the alcohol family are poisons; all will burn, andall 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 strongliquors. "Bitters" often contain as much alcohol as the strongestliquors, and sometimes more. 

9. Alcoholic liquors are sometimes adulterated, but they usually containno poison worse than alcohol. Pure alcohol is scarcely less dangerousthan 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 orabout their roots. 

12. Mr. Darwin proved that the vapor of alcohol will kill plants; alsothat 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 becomescooler instead of warmer. 

15. The danger of freezing to death when exposed to extreme cold isgreatly increased by taking alcohol. 

16. Stanley, and other African explorers, say that it is dangerous touse alcoholic drinks in hot climates. 

17. In very hot weather, persons who use alcoholic drinks are moresubject to sunstroke than those who do not. 

18. Beefsteak soaked in alcohol becomes tough like leather. An eggplaced in alcohol is hardened as though it had been boiled. 

19. The effect of alcohol upon the brain, nerves, and other tissues ofthe 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? Doesthe body resemble anything else besides a house? How is it like amachine? Name the different parts of the body. What is anatomy?physiology? hygiene?

CHAPTER II. A GENERAL VIEW OF THE BODY. --What are the mainparts 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 theframework 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? theabdomen?

CHAPTER IV. OUR FOODS. --Of what are our bodies made? What arefoods? Where do we get our foods? Name some animal foods; some vegetablefoods. What are poisons?

CHAPTER V. UNHEALTHFUL FOODS. --Is the flesh of diseased animalsgood for food? What can you say about unripe, stale, or mouldy foods?What is adulteration of foods? What foods are most likely to beadulterated? 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 willsatisfy thirst? Why do we need water? How does water sometimes becomeimpure? What is the effect of using impure water? What are theproperties of good water? Are tea and coffee good drinks? How is alcoholmade? Give familiar examples of fermentation. How are pure alcohol andstrong 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 thedigestive tube? Name the different digestive organs. How many sets ofteeth has a person in his lifetime? How many teeth in each set? How manypairs of salivary glands? What do they form? What is the gullet?Describe the stomach. What is the gastric juice? How long is theintestinal canal? What fluid is formed in the intestines? Where is theliver found, and how large is it? What does the liver produce? What isthe gall-bladder, and what is its use? What does the liver do besidesproducing bile? What and where is the pancreas? What does the pancreasdo? Where is the spleen? How many important organs of digestion arethere? How many digestive fluids?

CHAPTER VIII. DIGESTION OF A MOUTHFUL OF BREAD. --Name thedifferent processes of digestion [mastication, action of saliva, swallowing, action of stomach and gastric juice, action of bile, actionof pancreatic juice, action of intestines and intestinal juice, absorption, liver digestion]. Describe the digestion of a mouthful ofbread. Where is the food taken after it has been absorbed? What are thelacteals? What is the thoracic duct?

CHAPTER IX. BAD HABITS IN EATING. --What is indigestion? Mentionsome of the causes of indigestion. How does eating too fast causeindigestion? Eating too much? too frequently? Irregularly? when tired?How do tea and coffee impair digestion? Why is it harmful to use icedfoods and drinks? Why should we not eat pepper and other hot andirritating things? How should the teeth be cared for? How doestobacco-using affect the stomach? What dreadful disease is sometimescaused by tobacco? How does alcohol affect the gastric juice? thestomach? the liver?

CHAPTER X. A DROP OF BLOOD. --What does the blood contain? Howmany kinds of blood corpuscles are there? What work is done for the bodyby each kind of corpuscles?

CHAPTER XI. WHY THE HEART BEATS. --Where is the heart? Why doesthe heart beat? How many chambers has the heart? What are theblood-vessels? How many kinds of blood-vessels are there? Name them. What is the difference between venous blood and arterial blood? Whatchange occurs in the blood in the lungs? What is the pulse? How muchwork does the heart do every twenty-four hours? What are the lymphatics?What do they contain, and what is their purpose? What are lymphaticglands?

CHAPTER XII. HOW TO KEEP THE HEART AND BLOOD HEALTHY. --Namesome things likely to injure the heart or the blood. What is the effectof violent exercise? of bad air? of bad food? of loss of sleep? ofviolent anger? What can you say about clothing? What is the effect ofalcohol upon the blood? the heart? the bodily heat? What is the effectof tobacco upon the heart? the pulse? the blood? What is the effect oftea and coffee upon the heart? What is a cold? In a case of bleedingfrom a wound, how can you tell whether a vein or an artery is cut? Howwould you stop the bleeding from an artery? from a vein? How would youstop nose-bleed?

CHAPTER XIII. WHY AND HOW WE BREATHE. --What happens to alighted candle if shut up in a small, close place? to a mouse? Why isair so necessary for a burning candle and for animals? How is the heatof our bodies produced? Name the principal organs of breathing. Describe each. How do we use the lungs in breathing? How much air will aman's lungs hold? How much air do we use with each breath? Whatpoisonous substance does the air which we breathe out contain? Will acandle burn in air which has been breathed? What happens to animalsplaced in such air? What change takes place in the blood as it passesthrough the lungs? How do plants purify the air?

CHAPTER XIV. HOW TO KEEP THE LUNGS HEALTHY. --What is the thingmost necessary to preserve life? Name some of the ways in which theblood becomes impure. Why is bad-smelling air dangerous to health? Whatare germs? Why are some diseases "catching"? Name some such diseases. What should be done with a person who has a "catching" disease? What isthe effect of the breath upon the air? How much air is poisoned and madeunfit 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? everyhour? How do we get fresh air into our houses? Why are windows and doorsnot good means of ventilating in cold weather? How should a room beventilated? How should we use the lungs in breathing? What about theclothing in reference to the lungs? Why is it injurious to breathehabitually through the mouth? What is the effect of alcohol upon thelungs? What is the effect of tobacco-using upon the throat and nose?

CHAPTER XV. THE SKIN AND WHAT IT DOES. --How many layers in theskin? What is each called? To what is the color of the skin due? Whatglands are found in the true skin? What are the nails and what is theirpurpose? How does the hair grow? Name the different uses of the skin?

CHAPTER XVI. HOW TO TAKE CARE OF THE SKIN. --What happened tothe little boy who was covered with gold leaf? Why did he die? What isthe effect of neglecting to keep the skin clean? What is the effect ofwearing too much clothing and living in rooms which are too warm? Howshould 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 ofthe kidneys? How may we keep these organs healthy? What is the effect ofalcohol upon the kidneys?

CHAPTER XVIII. OUR BONES AND THEIR USES. --How many bones in thebody? What are the bones called when taken all together? Name theprincipal parts of the skeleton. Name the bones of the trunk, of thearms, of the legs. What are the uses of the bones? What is a joint? Whatis cartilage? By what are the bones held together? Of what are the boneslargely composed?

CHAPTER XIX. HOW TO KEEP THE BONES HEALTHY. --What sort ofbread is best for the bones? Why? If a child tries to walk too early whyare its legs likely to become crooked? What are the effects of sittingor lying in bad positions? Of wearing tight or poorly-fitting clothing?Of tight or high-heeled shoes? What injuries are likely to happen to thebones and joints by accident or rough play?

CHAPTER XX. THE MUSCLES AND HOW WE USE THEM. --How many musclesin the body? Of what are the muscles composed? How are many of themuscles connected to the bones? To what are all bodily movements due?How do the muscles act? What causes the muscles to act? Do all musclesact only when we will to have them act?

CHAPTER XXI. HOW TO KEEP THE MUSCLES HEALTHY. --What makes theright arm of the blacksmith stronger than the left one? How shouldexercise be taken? Mention some things in relation to the use of themuscles which we ought not to do, and state the reasons why. What is theeffect of alcohol upon the muscles? of tobacco? of tea and coffee?

CHAPTER XXII. HOW WE FEEL AND THINK. --With what part of thebody do we think? How many brains does a man have? How is each braindivided? Of what is the brain largely composed? Where do the nervesbegin? What is the spinal cord? Why does it cause pain to prick thefinger? How many kinds of nerves are there? (_Ans. _ Two; nerves offeeling and nerves of work. ) Name some of the different kinds of nervesof feeling? Name some of the different kinds of work controlled by thenerves of work. Of what use to the body are the brain and nerves? Howdoes the brain use the nerves? Of what use is the large brain? What doesthe little brain do? Of what use is the spinal cord?

CHAPTER XXIII. HOW TO KEEP THE BRAIN AND NERVESHEALTHY. --Mention some things which we need to do to keep the brainand nerves healthy. Mention some things which we ought not to do. 

CHAPTER XXIV. BAD EFFECTS OF ALCOHOL UPON THE BRAIN ANDNERVES. --What is the effect of alcohol upon the brain and nerves?Does alcohol produce real strength? Does it produce real warmth? Doesalcohol make people better or worse? What is the effect of tobacco uponthe 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. --Howmany 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? Howis the eyeball moved in the socket? How is the eye moistened? Of whatuse is the lens of the eye? Of what use is the pupil of the eye? How maywe preserve the eyesight?

Where are the nerves of smell located? Of what use is the sense ofsmell?

Where are the nerves of taste found? How is the sense of taste sometimesinjured or lost? What do we detect with the sense of taste? Of what useto us is the sense of taste?

With what sense do we feel objects? In what parts of the body is thissense most delicate? Upon what do all the special senses depend? Doesanything that injures the brain and nerves also injure the specialsenses? What is the effect of alcohol and tobacco upon the sense ofsight? How is the hearing affected by tobacco-using? The sense of smell?The sense of taste?

CHAPTER XXVI. ALCOHOL. --How is alcohol produced? In whatrespect is alcohol like kerosene oil? Is alcohol a dangerous thing evenif 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 hisbreath when a person has been drinking? Why? Does the breath ever takefire? 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 andgrains, or of decay? Is there more than one kind of alcohol? Mentionsome of the members of the alcohol family. In what ways are the membersof this family alike? Name some of the bad relations. Are cider andbeer, 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? Willalcohol kill plants? Describe Mr. Darwin's experiment which proved this. Can plants be made drunk by alcohol? Describe the experiment whichproves this. What has Dr. Roberts proven concerning the influence ofalcohol upon digestion? How are our bodies kept warm? Explain howalcohol makes the body cooler? Do Arctic explorers use alcohol? Why not?Does the use of alcohol prevent sunstroke? What do Stanley andLivingstone say about the use of alcohol in Africa? What is the effectof using alcohol upon meat and eggs? What is the effect of alcohol uponthe brain and other tissues of the body? Does alcohol cause insanity andother diseases of the brain and nerves?

FOOTNOTES:

[A] More properly _Carbonic dioxid_. 

[B] For the sake of brevity and clearness the author has included underthe term "little brain" the _medulla oblongata_ as well as the_cerebellum_. 

THE END. 

Aids to Field and Laboratory Work in Botany

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STORER AND LINDSAY'S

~Elementary Manual of Chemistry~

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~Chemistry~

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By E. B. ANDREWS, LL. D. Cloth, 12mo, 283 pages $1. 00

Adapted for elementary classes. Contains a special treatment of thegeology of the Mississippi Valley. 

_Copies of any of the above books will be sent, prepaid, to any addresson receipt of the price by the Publishers:_

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 * * * * *

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 inastronomical observatories and in teaching the subject has given himunusual qualifications and advantages for preparing an ideal text-book. 

The noteworthy feature which distinguishes this from other text-books onAstronomy is the practical way in which the subjects treated areenforced by laboratory experiments and methods. In this the authorfollows the principle that Astronomy is preëminently a science ofobservation and should be so taught. 

By placing more importance on the physical than on the mathematicalfacts of Astronomy the author has made every page of the book deeplyinteresting to the student and the general reader. The treatment of theplanets and other heavenly bodies and of the law of universalgravitation is unusually full, clear, and illuminative. The marvelousdiscoveries of Astronomy in recent years, and the latest advances inmethods of teaching the science, are all represented. 

The illustrations are an important feature of the book. Many of them areso ingeniously devised that they explain at a glance what pages of meredescription could not make clear. 

_Copies of Todd's New Astronomy will be sent, prepaid, to any address onreceipt of the price by the Publishers:_

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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 givethe student a general view of the subject, and at the same time to lay afoundation upon which more advanced studies may be built. The book isprimarily a laboratory manual and follows the method recommended by theCommittee of Ten and employed by the best teachers. So pursued, thestudy of botany provides the means of developing habits of close andaccurate observation and of cultivating the reasoning powers that canscarcely be claimed for any other subject taught in the schools. 

It provides a systematic outline of classification to serve as a guidein laboratory work and in the practical study of the life histories ofplants, their modes of reproduction, manner of life, etc. The treatmentis suggestive and general to adapt it to the courses of study indifferent schools, and to allow the teacher to follow his own ideas inselecting the work of his class. 

Clark's Laboratory Manual in Practical Botany _will be sent, prepaid, toany address on receipt of the price by the Publishers:_

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Important New Books

Crockett's Plane and Spherical Trigonometry

By C. W. CROCKETT, C. E. , Professor of Mathematics and Astronomyin 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 SphericalTrigonometry and their practical applications to Surveying, Geodesy, andAstronomy, with convenient and accurate "five place" tables for the useof 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 CivilEngineers, Professor of Geodesy, Road Engineering, and TopographicalDrawing 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 suchpractical subjects as system in office work, to labor-saving devices, tocoördinate methods, and to the explanation of difficulties encounteredby young surveyors. The appendix contains a large number of originalproblems, 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 andDirector 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 issimple, clear, scientific, and deeply interesting. The illustrationsinclude sketches from the author's laboratory and expeditions, andnumerous reproductions from astronomical photographs. 

_Copies of the above books will be sent, prepaid, to any address onreceipt of the price by the Publishers:_

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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 numerousillustrations. Price, $2. 00

The object of this book is to encourage the study of Birds by making ita pleasant and easy task. The treatment, while thoroughly scientific andaccurate, is interesting and popular in form and attractive to thereader or student. It covers the following divisions and subjects:

PART I. A general description of Birds and an explanation ofthe technical terms used by ornithologists. 

PART II. Classification and description of each species withKey. 

PART III. The study of Birds in the field, with Key for theiridentification. 

PART IV. Preparation of Bird specimens. 

The descriptions of the several species have been prepared with greatcare and present several advantages over those in other books. They areshort and so expressed that they may be recalled readily while lookingat the bird. They are thus especially adapted for field use. Theillustrations were drawn especially for this work. Their number, scientific accuracy, and careful execution add much to the value andinterest of the book. The general Key to Land and Water Birds and a veryfull index make the book convenient and serviceable both for the studyand for field work. 

_Apgar's Birds of the United States will be sent, prepaid, to anyaddress on receipt of the price by the Publishers:_

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