Project Gutenberg's First Book in Physiology and Hygiene, by J.H. Kellogg

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Title: First Book in Physiology and Hygiene

Author: J.H. Kellogg

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Language: English

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  [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 author
has aimed to accomplish in the preparation of the work have been:

1. To present as fully as possible and proper in a work of this
character a statement of the laws of healthful living, giving such
special prominence to the subject of stimulants and narcotics as its
recognized importance and the recent laws relating to the study of this
branch of hygiene demand.

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

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

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

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

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

In conclusion, the author would acknowledge his indebtedness for a large
number of useful suggestions and criticisms to several medical friends
and experienced teachers, and especially to Prof. Henry Sewall, of the
University of Michigan, for criticisms of the portions of the work
relating to Physiology.




         CONTENTS.

         CHAPTER                                    PAGE

         TO THE TEACHER                              iii

  I.     THE HOUSE WE LIVE IN                         1

  II.    A GENERAL VIEW OF THE BODY                   5

  III.   THE INSIDE OF THE BODY                       7

  IV.    OUR FOODS                                   11

  V.     UNHEALTHFUL FOODS                           14

  VI.    OUR DRINKS                                  19

  VII.   HOW WE DIGEST                               27

  VIII.  DIGESTION OF A MOUTHFUL OF BREAD            35

  IX.    BAD HABITS IN EATING                        39

  X.     A DROP OF BLOOD                             46

  XI.    WHY THE HEART BEATS                         48

  XII.   HOW TO KEEP THE HEART AND THE BLOOD HEALTHY 56

  XIII.  WHY AND HOW WE BREATHE                      63

  XIV.   HOW TO KEEP THE LUNGS HEALTHY               75

  XV.    THE SKIN AND WHAT IT DOES                   81

  XVI.   HOW TO TAKE CARE OF THE SKIN                88

  XVII.  THE KIDNEYS AND THEIR WORK                  91

  XVIII. OUR BONES AND THEIR USES                    93

  XIX.   HOW TO KEEP THE BONES HEALTHY              100

  XX.    THE MUSCLES, AND HOW WE USE THEM           105

  XXI.   HOW TO KEEP THE MUSCLES HEALTHY            109

  XXII.  HOW WE FEEL AND THINK                      115

  XXIII. HOW TO KEEP THE BRAIN AND NERVES HEALTHY   126

  XXIV.  BAD EFFECTS OF ALCOHOL UPON THE BRAIN AND
           NERVES                                   130

  XXV.   HOW WE HEAR, SEE, SMELL, TASTE; AND FEEL   138

  XXVI.  ALCOHOL                                    154

         QUESTIONS FOR REVIEW                       170




FIRST BOOK
OF
PHYSIOLOGY AND HYGIENE.




CHAPTER I.

THE HOUSE WE LIVE IN.


~1. Object of this Book.~--The object of this book is to tell the little
boys and girls who read it about a wonderful house. You have all seen
some very beautiful houses. Perhaps they were made of brick or stone,
with fine porches, having around them tall shade trees, smooth lawns,
pretty flower-beds, walks, and sparkling fountains.

~2.~ Perhaps some of you live in such a house, or have visited some
friend who does. If so, you know that the inside of the house is even
more beautiful than the outside. There are elegant chairs and sofas in
the rooms, rich carpets and rugs on the floors, fine mirrors and
beautiful pictures upon the walls--everything one could wish to have in
a house. Do you not think such a house a nice one to live in?

~3. The Body is Like a House.~--Each of us has a house of his own which
is far more wonderful and more curious than the grandest palace ever
built. It is not a very large house. It has just room enough in it for
one person. This house, which belongs to each one of us, is called the
body.

~4. What is a Machine?~--Do you know what a machine is? Men make
machines to help them work and to do many useful things. A wheelbarrow
or a wagon is a machine to carry loads. A sewing-machine helps to make
garments for us to wear. Clocks and watches are machines for keeping
time.

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

~6. The Body is Like a Machine.~--In some ways the body is more like a
machine than like a house. It has many different parts which are made
to do a great many different kinds of work. We see with our eyes, hear
with our ears, walk with our legs and feet, and do a great many things
with our hands. If you have ever seen the inside of a watch or a clock
you know how many curious little wheels it has. And yet a watch or a
clock can do but one thing, and that is to tell us the time of day. The
body has a great many more parts than a watch has, and for this reason
the body can do many more things than a watch can do. It is more
difficult, too, to learn about the body than about a watch.

~7.~ If we want to know all about a machine and how it works, we must
study all its different parts and learn how they are put together, and
what each part does. Then, if we want the machine to work well and to
last a long time, we must know how to use it and how to take proper care
of it. Do you think your watch would keep the time well if you should
neglect to wind it, or if you should break any of its wheels?

~8.~ It is just the same with the human machine which we call the body.
We must learn its parts, and what they are for, how they are made, how
they are put together, and how they work. Then we must learn how to take
proper care of the body, so that its parts will be able to work well
and last a long time.

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

~10.~ The study of the various parts of the body and how they are put
together is _anatomy_ (a-nat´-o-my). The study of what each part of the
body does is _physiology_ (phys-i-ol´-o-gy). The study of how to take
care of the body is _hygiene_ (hy´-jeen).


SUMMARY.

1. The body is something like a house. It has an outside and an inside;
it has hollow places inside of it, and there are many wonderful things
in them.

2. The body is also like a wonderful machine.

3. It is necessary to take good care of the body in order to keep it
well and useful, just as we would take good care of a machine to keep it
from wearing out too soon.

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

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

6. The study of the various parts of the body, how they are formed and
joined together, is anatomy. Physiology tells us what the body does,
hygiene tells us how to take care of it.




CHAPTER II

A GENERAL VIEW OF THE BODY.


~1. Parts of the Body.~--What do we call the main part of a tree? The
trunk, you say. The main part of the body is also called its _trunk_.
There are two arms and two legs growing out of the human trunk. The
branches of a tree we call limbs, and so we speak of the arms and legs
as _limbs_. We sometimes call the arms the _upper extremities_, and the
legs the _lower extremities_. At the top of the trunk is the head.

~2. Names of the Parts.~--Now let us look more closely at these
different parts. As we speak the name of each part, let each one touch
that part of himself which is named. We will begin with the head. The
chief parts of the head are the _skull_ and the _face_. The _forehead_,
the _temples_, the _cheeks_, the _eyes_, the _ears_, the _nose_, the
_mouth_, and the _chin_ are parts of the face.

~3.~ The chief parts of the trunk are the _chest_, the _abdomen_
(ab-do´-men), and the _backbone_. The head is joined to the trunk by the
_neck_.

~4.~ Each arm has a _shoulder_, _upper-arm_, _fore-arm_, _wrist_, and
_hand_. The _fingers_ are a part of the hand.

~5.~ Each leg has a _hip_, _thigh_, _lower leg_, _ankle_, and _foot_.
The _toes_ are a part of the foot.

~6.~ Our hands and face and the whole body are covered with something as
soft and smooth as the finest silk. It is the _skin_. What is it that
grows from the skin on the head? and what at the ends of the fingers and
the toes? We shall learn more about the skin, the hair, and the nails in
another lesson.

~7.~ The body has two sides, the right side and the left side, which are
alike. We have two eyes, two ears, two arms, etc. We have but one nose,
one mouth, and one chin, but each of these organs has two halves, which
are just alike.


SUMMARY.

1. The body has a head and trunk, two arms, and two legs.

2. The parts of the head are the skull and face. The forehead, temples,
cheeks, eyes, ears, nose, mouth and chin are parts of the face.

3. The parts of the trunk are, the chest, abdomen, and backbone. The
neck joins the head and trunk.

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

5. Each leg has a hip, thigh, lower leg, ankle, and foot. The toes
belong to the foot.

6. The whole body is covered by the skin.

7. The two sides of the body are alike.




CHAPTER III.

THE INSIDE OF THE BODY.


~1.~ Thus far we have taken only a brief look at the outside of the
body, just as if we had looked at the case of a watch, and of course we
have found out very little about its many wonderful parts. Very likely
you want to ask a great many questions, such as, How does the inside of
the body look? What is in the skull? What is in the chest? What is in
the abdomen? Why do we eat and drink? Why do we become hungry and
thirsty? What makes us tired and sleepy? How do we keep warm? Why do we
breathe? How do we grow? How do we move about? How do we talk, laugh,
and sing? How do we see, hear, feel, taste, and smell? How do we
remember, think, and reason? All these, and a great many more
interesting questions, you will find answered in the following lessons,
if you study each one well.

~2.~ When we study the inside of the body, we begin to understand how
wonderfully we are made. We cannot all see the inside of the body, and
it is not necessary that we should do so. Many learned men have spent
their whole lives in seeking to find out all about our bodies and the
bodies of various animals.

~3. The Bones.~--If you take hold of your arm, it seems soft on the
outside; and if you press upon it, you will feel something hard inside.
The soft part is called _flesh_. The hard part is called _bone_. If you
wish, you can easily get one of the bones of an animal at the butcher's
shop, or you may find one in the fields.

~4. The Skeleton.~--All the bones of an animal, when placed properly
together, have nearly the shape of the body, and are called the
_skeleton_ (skel´-e-ton). The skeleton forms the framework of the body,
just as the heavy timbers of a house form its framework. It supports all
the parts.

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

~6. The Backbone.~--The framework of the back is called the _backbone_.
This is not a single bone, but a row of bones arranged one above
another. Each bone has a hole through it, about as large as one of your
fingers. A large branch from the brain, called the _spinal cord_, runs
down through the middle of the backbone, so that the separate bones look
as if they were strung on the spinal cord, like beads on a string.

~7. The Trunk.~--The trunk of the body, like the skull, is hollow. Its
walls are formed partly by the backbone and the ribs and partly by
flesh. A fleshy wall divides the hollow of the trunk into two parts, an
upper chamber called the _chest_, and a lower called the _abdomen_.

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

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

~10. Care of the Body.~--We have only begun to study the beautiful
house in which we live, and yet have we not learned enough to show us
how great and wise is the Creator who made us and all the wonderful
machinery within our bodies? If some one should give you a beautiful
present, would you treat it carelessly and spoil it, or would you take
good care of it and keep it nice as long as possible? Ought we not to
take such care of our bodies as to keep them in that perfect and
beautiful condition in which our kind and good Creator gave them to us?


SUMMARY.

1. The body has a framework, called the skeleton.

2. The skeleton is made up of many different parts, each of which is
called a bone.

3. The bones are covered by the flesh.

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

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

6. The trunk is hollow, and has two chambers, one called the cavity of
the chest, and the other the cavity of the abdomen.

7. The chest contains the two lungs and the heart.

8. The abdomen contains the stomach, liver, and many other very
important organs.

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




CHAPTER IV.

OUR FOODS.


~1.~ We all know very well that if we do not eat we shall rapidly lose
in weight, and become very weak and feeble. Did you ever think how much
one eats in the course of a lifetime? Let us see if we can figure it up.
How much do you suppose a boy eats in a day? Let us say two pounds. How
much does he eat in a year? There are three hundred and sixty-five days
in a year; 365 multiplied by 2 equals 730. So a boy eats a good many
times his own weight in a year. How much would a person eat in fifty
years?

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

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

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

~5.~ The principal animal foods are milk, cheese, eggs, and the
different kinds of flesh--beef, mutton, pork, fish, fowl, and wild game.

We obtain a great many more kinds of food from plants than from animals.
Most plant foods are included in three classes--_fruits_, _grains_, and
_vegetables_.

~6.~ _Fruits_ are the fleshy parts of plants which contain the seeds.
Our most common fruits are apples, pears, peaches, plums, cherries, and
various kinds of nuts. Perhaps you know of some other kinds of fruits
besides those mentioned. Your teacher will tell you that tomatoes,
watermelons, and pumpkins are really fruits, though they are not
generally so called.

~7.~ The seeds of grass-like plants are known as _grains_, of which we
have wheat, rye, barley, corn, and rice. There are a few seeds that grow
in pods, such as pease and beans, which somewhat resemble grains.

~8.~ We eat the leaves, stems, or roots of some plants, as cabbages,
celery, turnips, and potatoes. Foods of this kind are called
_vegetables_.

~9.~ There are other things, which, if we eat or drink them, will make
us sick or otherwise do us harm. These are called _poisons_. Only such
food as is pure and free from poisons is good or safe for us to use.

~10. Narcotics and Stimulants.~--There are a number of substances known
as narcotics and stimulants, which, from their effects upon the body,
may be classed as poisons. Tobacco, opium, alcohol, and chloral are
included in this class. Death has often been caused by taking small
quantities of any of these poisonous drugs. We shall learn more of the
effects of tobacco and alcohol in future lessons.


SUMMARY.

1. Our bodies are made of what we eat.

2. Things which will help us to grow strong and well, if we eat them,
are foods.

3. We get foods from plants and animals.

4. There are several kinds of animal foods, and three classes of plant
foods--fruits, grains, and vegetables.

5. Things which make us sick when we eat them, are poisons.




CHAPTER V.

UNHEALTHFUL FOODS.


~1.~ Most persons eat many things which are not good for them. Some
people do not stop to think whether what they eat is good for them or
likely to do them harm. Sometimes, without knowing it, we eat things
which are harmful to us. Do you not think that we should try to learn
what is good to eat and what is not good, and then be very careful not
to eat anything which is likely to do us harm?

~2. Diseased Foods.~--When a person is sick, he is said to be diseased.
Animals are sometimes sick or diseased. Vegetables are also sometimes
diseased. Animals and vegetables that are diseased are not good for
food. Dishonest men, however, sometimes sell them to those who do not
know that they are unfit to be eaten.

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

~4.~ Beef and mutton may be diseased also. Sheep and cattle are
sometimes sick of diseases very much like those which human beings
have. Meat which is pale, yellowish, or of a dark red color, is
unhealthful, and should not be eaten. Meat should never be eaten raw. It
should always be well cooked.

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

~6. Stale or Decayed Foods.~--Food which has been allowed to stand until
it is spoiled, or has become _stale_, _musty_, or _mouldy_, such as
mouldy bread or fruit, or tainted meat, is unfit to be eaten, and is
often a cause of very severe sickness. Canned fish or other meats spoil
very quickly after the cans are opened, and should be eaten the same
day.

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

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

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

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

~11. Condiments or Seasonings.~--These are substances which are added to
our food for the purpose of giving to it special flavors. Condiments are
not foods, because they do not nourish the body in any way, and are not
necessary to preserve it in health.

~12.~ The most common condiments are, mustard, pepper, pepper-sauce,
ginger, cayenne-pepper, and spices. All these substances are irritating.
If we put mustard upon the skin, it will make the skin red, and in a
little time will raise a blister. If we happen to get a little pepper in
the eye, it makes it smart and become very red and inflamed. When we
take these things into the stomach, they cause the stomach to smart,
and its lining membrane becomes red just as the skin or the eye does.

~13.~ Nature has put into our foods very nice flavors to make us enjoy
eating them. Condiments are likely to do us great harm, and hence it is
far better not to use them.

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

[Illustration: Tobacco-Plant.]

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

~16.~ You know that tobacco makes people sick when they first begin to
use it. This is because it contains a very deadly poison, called
_nicotine_.

~17.~ If you give tobacco to a cat or a dog, it will become very sick. A
boy once gave a piece of tobacco to a monkey, which swallowed it not
knowing what a bad thing it was. The monkey soon became sick and died.

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


SUMMARY.

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

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

3. Foods are sometimes spoiled by having things mixed with them which
are not food, or which are poisonous.

4. The foods most liable to be adulterated in this way are milk, sugar,
and butter.

5. Tobacco, while not actually eaten, is thought by some persons to be a
food, but it is not. It is a poison, and injures all who use it.

6. Boys who use tobacco do not grow strong in body and mind.




CHAPTER VI.

OUR DRINKS.


~1.~ Water is really the only drink. It is the only substance which will
satisfy thirst. All other fluids which we drink consist mostly of water.
Thus, lemonade is lemon-juice and water. Milk is chiefly water. Wine,
beer, cider, and such liquids contain alcohol and many other things,
mixed with water.

~2. Why we Need Water.~--If we should wet a sponge and lay it away, it
would become dry in a few hours, as the water would pass off into the
air. Our bodies are losing water all the time, and we need to drink to
keep ourselves from drying up.

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

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

~5. Impure Water.~--Most waters have more or less substances dissolved
in them. Water which has much lime in it is called hard water. Such
water is not so good to drink, or for use in cooking, as soft water.
That water is best which holds no substances in solution. Well-water
sometimes contains substances which soak into wells from vaults or
cesspools. Slops which are poured upon the ground soak down out of
sight; but the foul substances which they contain are not destroyed.
They remain in the soil, and when the rains come, they are washed down
into the well if it is near by. You can see some of the things found in
bad water in the illustration given on opposite page.

~6.~ It is best not to drink iced water when the body is heated, or
during meals. If it is necessary to drink very cold water, the bad
effects may be avoided by sipping it very slowly.

~7. Tea and Coffee.~--Many people drink tea or coffee at their meals,
and some persons think that these drinks are useful foods; but they
really have little or no value as foods. Both tea and coffee contain a
poison which, when separated in a pure form, is so deadly that a very
small quantity is enough to kill a cat or a dog. This poison often does
much harm to those who drink tea or coffee very strong for any great
length of time.

[Illustration: A DROP OF IMPURE WATER MAGNIFIED.]

~8. Alcohol~ (al´-co-hol).--All of you know something about alcohol.
Perhaps you have seen it burn in a lamp. It will burn without a lamp, if
we light it. It is so clear and colorless that it looks like water. The
Indians call it "fire-water." Alcohol differs very much from foods. It
is not produced from plants, as fruits and grains are; neither is it
supplied by Nature ready for our use, as are air and water.

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

[Illustration: FERMENTATION.]

~10.~ Any moist substance or liquid which contains sugar will ferment if
yeast is added to it, or if it is kept in a warm place. You know that
canned fruit sometimes spoils. This is because it ferments. Fermentation
is a sort of decay. When the juice of grapes, apples, or other fruit is
allowed to stand in a warm place it "works," or ferments, and thus
produces alcohol. Wine is fermented grape-juice; hard cider is fermented
apple-juice.

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

~12.~ All fermented liquids contain more or less alcohol, mixed with
water and a good many other things. Rum, brandy, gin, whiskey, and pure
alcohol are made by separating the alcohol from the other substances.
This is done by means of a still, and is called _distillation_.

[Illustration: DISTILLATION.]

~13.~ You can learn how a still separates the alcohol by a little
experiment. When a tea-pot is boiling on the stove and the steam is
coming out at the nozzle, hold up to the nozzle a common drinking-glass
filled with iced water, first taking care to wipe the outside of the
glass perfectly dry. Little drops of water will soon gather upon the
side of the glass. If you touch these to the tongue you will observe
that they taste of the tea. It is because a little of the tea has
escaped with the steam and condensed upon the glass. This is
distillation.

~14.~ If the tea-pot had contained wine, or beer, or hard cider, the
distilled water would have contained alcohol instead of tea. By
distilling the liquid several times the alcohol may be obtained almost
pure.

~15. Alcohol kills Animals and Plants.~--Strong alcohol has a deadly
effect upon all living things. Once a man gave a dog a few
tablespoonfuls of alcohol, and in a little while the dog was dead. If
you should pour alcohol upon a plant it would die very soon.

~16.~ A man once made a cruel experiment. He put some minnows into a jar
of water and then poured in a few teaspoonfuls of alcohol. The minnows
tried very hard to get out, but they could not, and in a little while
they were all dead, poisoned by the alcohol. A Frenchman once gave
alcohol to some pigs with their food. They soon became sick and died.

~17. Alcohol not a Food.~--There are some people who imagine that
alcohol is good for food because it is made from fruits and grains which
are good for food. This is a serious mistake. A person can live on the
fruits or grains from which alcohol is made, but no one would attempt
to live upon alcohol. If he did, he would soon starve to death. In fact,
men have often died in consequence of trying to use whiskey in place of
food.

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

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

~20.~ Another very serious thing to be thought of is that if a person
forms the habit of drinking wine, cider, or other fermented drinks, he
becomes so fond of the _effect they produce_ that he soon wants some
stronger drink, and thus he is led to use whiskey or other strong
liquors. On this account it is not safe to use any kind of alcoholic
drinks, either fermented or distilled. The only safe plan is to avoid
the use of every sort of stimulating or intoxicating drinks.

~21.~ It has been found by observation that those persons who use
intoxicating drinks are not so healthy as those who do not use them,
and, as a rule, they do not live so long.

~22.~ This is found to be true not only of those who use whiskey and
other strong liquors, but also of those who use fermented drinks, as
wine and beer. Beer drinkers are much more likely to suffer from disease
than those who are strictly temperate. It is often noticed by physicians
that when a beer-drinker becomes sick or meets with an accident, he does
not recover so readily as one who uses no kind of alcoholic drinks.

~23.~ Alcoholic drinks not only make people unhealthy and shorten their
lives, but they are also the cause of much poverty and crime and an
untold amount of misery.


SUMMARY.

1. Water is the only thing that will satisfy thirst.

2. In going through our bodies, water washes out many impurities. We
also need water to soften our food.

3. The purest water is the best. Impure water causes sickness.

4. Good water has no color, taste, or odor.

5. Tea and coffee are not good drinks. They are very injurious to
children, and often do older persons much harm.

6. Alcohol is made by fermentation.

7. Pure alcohol and strong liquors are made by distillation.

8. Alcohol is not a food, it is a poison. It kills plants and animals,
and is very injurious to human beings.

9. Even the moderate use of alcoholic drinks produces disease and
shortens life.




CHAPTER VII.

HOW WE DIGEST.


~1.~ Did you ever see a Venus's fly-trap? This curious plant grows in
North Carolina. It is called a fly-trap because it has on each of its
leaves something like a steel-trap, by means of which it catches flies.
You can see one of these traps in the picture. When a fly touches the
leaf, the trap shuts up at once, and the poor fly is caught and cannot
get away. The harder it tries to escape, the more tightly the trap
closes upon it, until after a time it is crushed to death.

[Illustration: VENUS'S FLY-TRAP.]

~2.~ But we have yet to learn the most curious thing about this strange
plant, which seems to act so much like an animal. If we open the leaf
after a few days, it will be found that the fly has almost entirely
disappeared. The fly has not escaped, but it has been dissolved by a
fluid formed inside of the trap, and the plant has absorbed a portion of
the fly. In fact, it has really eaten it. The process by which food is
dissolved and changed so that it can be absorbed and may nourish the
body, is called _digestion_ (di-ges´-tion).

~3.~ The Venus's fly-trap has a very simple way of digesting its food.
Its remarkable little trap serves it as a mouth to catch and hold its
food, and as a stomach to digest it. The arrangement by which our food
is digested is much less simple than this. Let us study the different
parts by which this wonderful work is done.

[Illustration: THE DIGESTIVE TUBE.]

~4. The Digestive Tube.~--The most important part of the work of
digesting our food is done in a long tube within the body, called the
_digestive tube_ or _canal_.

~5.~ This tube is twenty-five or thirty feet long in a full-grown man;
but it is so coiled up and folded away that it occupies but little
space. It begins at the mouth, and ends at the lower part of the trunk.
The greater part of it is coiled up in the abdomen.

~6. The Mouth.~--The space between the upper and the lower jaw is called
the _mouth_. The lips form the front part and the cheeks the sides. At
the back part are three openings. One, the upper, leads into the nose.
There are two lower openings. One of these leads into the stomach, and
the other leads to the lungs. The back part of the mouth joins the two
tubes which lead from the mouth to the lungs and the stomach, and is
called the _throat_. The mouth contains the _tongue_ and the _teeth_.

[Illustration: THE TEETH.]

~7. The Teeth.~--The first teeth, those which come when we are small
children, are called _temporary_ or _milk teeth_. We lose these teeth
as the jaws get larger and the second or _permanent_ teeth take their
place. There are twenty teeth in the first set, and thirty-two in the
second. Very old persons sometimes have a third set of teeth.

[Illustration: SALIVARY GLANDS.]

~8. The Salivary~ (sal´-i-vary)~ Glands.~--There are three pairs of
_salivary glands_. They form a fluid called the _saliva_ (sa-li´-va). It
is this fluid which moistens the mouth at all times. When we eat or
taste something which we like, the salivary glands make so much saliva
that we sometimes say the mouth waters. One pair of the salivary glands
is at the back part of the lower jaw, in front of the ears. The other
two pairs of glands are placed at the under side of the mouth. The
saliva produced by the salivary glands is sent into the mouth through
little tubes called _ducts_.

~9. The Gullet.~--At the back part of the throat begins a narrow tube,
which passes down to the stomach. This tube is about nine inches long.
It is called the _gullet_, _food-pipe_, or _oesophagus_
(e-soph´-a-gus).

~10. The Stomach.~--At the lower end of the oesophagus the digestive
tube becomes enlarged, and has a shape somewhat like a pear. This is the
_stomach_. In a full-grown person the stomach is sufficiently large to
hold about three pints. At each end of the stomach is a narrow opening
so arranged that it can be opened or tightly closed, as may be
necessary. The upper opening allows the food to pass into the stomach,
the lower one allows it to pass out into the intestines. This opening is
called the _pylorus_ (py-lo´-rus), or gate-keeper, because it closes so
as to keep the food in the stomach until it is ready to pass out.

~11.~ In the membrane which lines the stomach there are many little
pocket-like glands, in which a fluid called the _gastric juice_ is
formed. This fluid is one of the most important of all the fluids formed
in the digestive canal.

[Illustration: GASTRIC GLAND.]

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

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

~14.~ The bile is a bitter fluid of a golden-brown color. It is carried
to the intestine by means of a little tube or duct, which enters the
small intestine a few inches below the stomach. When the bile is made
faster than it is needed for immediate use, it is stored up in a little
pear-shaped sac called the _gall-bladder_, which hangs from the under
side of the liver.

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

~16. The Pancreas~(pan´-cre-as).--The _pancreas_ is another large and
very important gland which is found close to the stomach, lying just
behind it in the abdominal cavity. The pancreas forms a fluid called the
_pancreatic juice_, which enters the small intestine at nearly the same
place as the bile.

~17. The Spleen.~--Close to the pancreas, at the left side of the body,
is a dark, roundish organ about the size of the fist, called the
_spleen_. It is not known that the spleen has much to do in the work of
digestion, but it is so closely connected with the digestive organs that
we need to know about it.

~18.~ Please note that there are five important organs of digestion. The
mouth, the stomach, the intestines, the pancreas, and the liver.

~19.~ Also observe that there are five digestive fluids, saliva,
gastric juice, bile, pancreatic juice, and intestinal juice.


SUMMARY.

1. The process of dissolving and changing the food so that it may be
absorbed and may nourish the body is digestion.

2. The work of digestion is chiefly done in the digestive tube or canal,
which is about thirty feet in length.

3. The mouth contains the teeth, and has three pairs of salivary glands
connected with it, which make saliva.

4. The gullet leads from the mouth to the stomach.

5. The stomach is pear-shaped, and holds about three pints.

6. It has an upper and a lower opening, each of which is guarded by a
muscle, which keeps its contents from escaping.

7. The lower opening of the stomach is called the pylorus.

8. The stomach forms the gastric juice.

9. The intestines are about twenty-five feet long. They form the
intestinal juice.

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

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

12. The pancreas is a gland which lies just back of the stomach. It
makes pancreatic juice.

13. The spleen is found near the pancreas.

14. There are five important digestive organs--the mouth, the stomach,
the intestines, the liver, and the pancreas.

15. There are five digestive fluids--saliva, gastric juice, intestinal
juice, bile, and pancreatic juice.




CHAPTER VIII.

DIGESTION OF A MOUTHFUL OF BREAD.


~1.~ Let us suppose that we have eaten a mouthful of bread, and can
watch it as it goes through all the different processes of digestion.

~2. Mastication.~--First, we chew or masticate the food with the teeth.
We use the tongue to move the food from one side of the mouth to the
other, and to keep the food between the teeth.

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

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

~5. Stomach Digestion.~--As soon as the morsel of food enters the
stomach, the gastric juice begins to flow out of the little glands in
which it is formed. This mingles with the food and digests another
portion which the saliva has not acted upon. While this is being done,
the stomach keeps working the food much as a baker kneads dough. This is
done to mix the gastric juice with the food.

~6.~ After an hour or two the stomach squeezes the food so hard that a
little of it, which has been digested by the gastric juice and the
saliva, escapes through the lower opening, the pylorus, of which we have
already learned. As the action of the stomach continues, more of the
digested food escapes, until all that has been properly acted upon has
passed out.

~7. Intestinal Digestion.~--We sometimes eat butter with bread, or take
some other form of fat in our food. This is not acted upon by the saliva
or the gastric juice. When food passes out of the stomach into the small
intestine, a large quantity of bile is at once poured upon it. This bile
has been made beforehand by the liver and stored up in the gall-bladder.
The bile helps to digest fats, which the saliva and the gastric juice
cannot digest.

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

~9.~ The intestinal juice digests nearly all the different elements of
the food, so that it is well fitted to complete the wonderful process by
which the food is made ready to enter the blood and to nourish the body.

~10.~ While the food is being acted upon by the bile, the pancreatic
juice, and intestinal juice, it is gradually moved along the intestines.
After all those portions of food which can be digested have been
softened and dissolved, they are ready to be taken into the blood and
distributed through the body.

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

~12. Liver Digestion.~--After the food has been absorbed, the most of it
is carried to the liver, where the process of digestion is completed.
The liver also acts like an inspector to examine the digested food and
remove hurtful substances which may be taken with it, such as alcohol,
mustard, pepper, and other irritating things.

~13. The Thoracic Duct.~--A portion of the food, especially the digested
fats, is absorbed by a portion of the lymphatic vessels called
_lacteals_, which empty into a small vessel called the _thoracic duct_.
This duct passes upward in front of the spine and empties into a vein
near the heart.


SUMMARY.

How a mouthful of food is digested:

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

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

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

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

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

6. The greater portion of the food is next passed through the liver,
where hurtful substances are removed.

7. A smaller portion is carried through the thoracic duct and emptied
into a vein near the heart.




CHAPTER IX.

BAD HABITS IN EATING.


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

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

~3. Eating too Often~--Many children make themselves sick by eating too
often. It is very harmful to take lunches or to eat at other than the
proper meal-times. The stomach needs time to rest, just as our legs and
arms and the other parts of the body do. For the same reason, it is well
for us to avoid eating late at night. The stomach needs to sleep with
the rest of the body. If one goes to bed with the stomach full of food,
the stomach cannot rest, and the work of digestion will go on so slowly
that the sleep will likely be disturbed. Such sleep is not refreshing.

~4.~ If we wish to keep our digestive organs in good order, we must take
care to eat at regular hours. We ought not to eat when we are very
tired. The stomach cannot digest well when we are very much fatigued.

~5. Sweet Foods.~--We ought not to eat too much sugar or sweet foods, as
they are likely to sour or ferment in the stomach, and so make us sick.
Candies often contain a great many things which are not good for us, and
which may make us sick. The colors used in candies are sometimes
poisonous. The flavors used in them are also sometimes very harmful.

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

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

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

~9. Things sometimes Eaten which are not Foods.~--Things which are not
foods are often used as foods, such as mustard, pepper, and the various
kinds of seasonings. Soda, saleratus, and baking-powders also belong to
this class. All of these substances are more or less harmful,
particularly mustard, pepper, and hot sauces.

~10. Common Salt.~--The only apparent exception to the general rule that
all condiments and other substances which are not foods are harmful is
in the case of common salt. This is very commonly used among civilized
nations, although there are many barbarous tribes that never taste it.
It is quite certain that much more salt is used than is needed. When
much salt is added to the food, the action of the digestive fluids is
greatly hindered. Salt meats, and other foods which have much salt added
to them, are hard to digest because the salt hardens the fibres of the
meat, so that they are not easily dissolved by the digestive fluids.

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

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

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

~14. Tobacco.~--When a person first uses tobacco, it is apt to make him
very sick at the stomach. After he has used tobacco a few times it does
not make him sick, but it continues to do his stomach and other organs
harm, and after a time may injure him very seriously. Smokers sometimes
suffer from a horrible disease of the mouth or throat known as cancer.

~15. Effects of Alcohol upon the Stomach.~--If you should put a little
alcohol into your eye, the eye would become very red. When men take
strong liquors into their stomachs, the delicate membrane lining the
stomach becomes red in the same way. Perhaps you will ask how do we know
that alcohol has such an effect upon the stomach. More than sixty years
ago there lived in Michigan a man named Alexis St. Martin. One day he
was, by accident, shot in such a way that a large opening was made right
through the skin and flesh and into the stomach. The good doctor who
attended him took such excellent care of him that he got well. But when
he recovered, the hole in his stomach remained, so that the doctor could
look in and see just what was going on. St. Martin sometimes drank
whiskey, and when he did, the doctor often looked into his stomach to
see what the effect was, and he noticed that the inside of the stomach
looked very red and inflamed.

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

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


SUMMARY.

                                     {Eating too fast.
                                     {Eating too much.
                                     {Eating too frequently.
                                     {Eating irregularly.
  1. CAUSES OF INDIGESTION.          {Eating when tired.
                                     {Eating too much of sweet foods.
                                     {Eating too many kinds of food
                                       at a meal.
                                     {Using iced foods or drinks.

2. Irritating substances and things which are not foods should not be
eaten.

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

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

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




CHAPTER X.

A DROP OF BLOOD.


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

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

~3. The Blood Corpuscles.~--If you should look at a tiny drop of blood
through such a microscope, you would find it to be full of very small,
round objects called _blood corpuscles_.

~4.~ You would notice also that these corpuscles are of two kinds. Most
of them are slightly reddish, and give to the blood its red color. A
very few are white.

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

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

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


SUMMARY.

1. The blood contains very small objects called blood corpuscles.

2. There are two kinds of corpuscles, red and white.

3. The red corpuscles carry oxygen.

4. The white corpuscles repair parts that are worn.

5. The corpuscles float in a clear, almost colorless fluid, which
nourishes the body.




CHAPTER XI.

WHY THE HEART BEATS.


~1.~ If you place your hand on the left side of your chest, you will
feel something beating. If you cannot feel the beats easily, you may run
up and down stairs two or three times, and then you can feel them very
distinctly. How many of you know the name of this curious machine inside
the chest, that beats so steadily? You say at once that it is the heart.

[Illustration: THE HEART.]

~2.~ The Heart.--The heart may be called a live pump, which keeps
pumping away during our whole lives. If it should stop, even for a
minute or two, we would die. If you will place your hand over your heart
and count the beats for exactly one minute, you will find that it beats
about seventy-five or eighty times. When you are older, your heart will
beat a little more slowly. If you count the beats while you are lying
down, you will find that the heart beats more slowly than when you are
sitting or standing. When we run or jump, the heart beats much harder
and faster.

~3. Why the Heart Beats.~--We have learned in preceding lessons that the
digested food is taken into the blood. We have also learned that both
water and oxygen are taken into the blood. Thus the blood contains all
the materials that are needed by the various parts of the body to make
good the wastes that are constantly taking place. But if the blood were
all in one place it could do little good, as the new materials are
needed in every part of the body. There has been provided a wonderful
system of tubes running through every part of the body. By means of
these tubes the blood is carried into every part where it is required.
These tubes are connected with the heart. When the heart beats, it
forces the blood through the tubes just as water is forced through a
pipe by a pump or by a fire-engine.

~4. The Heart Chambers.~--The heart has four chambers, two upper and
two lower chambers. The blood is received into the upper chambers, and
is then passed down into the lower chambers. From the lower chambers it
is sent out to various parts of the body.

[Illustration: THE INSIDE OF THE HEART.]

~5. The Blood-Vessels.~--The tubes through which the blood is carried
are called _blood-vessels_. There are three kinds of blood-vessels. One
set carry the blood away from the heart, and are called _arteries_
(ar´-te-ries). Another set return the blood to the heart, and are called
_veins_. The arteries and veins are connected at the ends farthest from
the heart by many very small vessels. These minute, hairlike vessels are
called _capillaries_ (cap´-il-la-ries).

~6. The Arteries.~--An artery leads out from the lower chamber of each
side of the heart. The one from the right side of the heart carries the
blood only to the lungs. The one from the left side of the heart carries
blood to every part of the body. It is the largest artery in the body,
and is called the _aorta_. Soon after it leaves the heart the aorta
begins to send out branches to various organs. These divide in the
tissues again and again until they become so small that only one
corpuscle can pass through at a time, as shown in the colored plate.
(Frontispiece.)

~7. The Veins.~--These very small vessels now begin to unite and form
larger ones, the veins. The small veins join to form larger ones, until
finally all are gathered into two large veins which empty into the upper
chamber of the right side of the heart. The veins which carry blood from
the lungs to the heart empty into the upper chamber of the left side of
the heart.

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

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

~10. Change of Blood in the Lungs.~--Exactly the opposite change occurs
in the blood when it passes through the lungs. The blood which has been
gathered up from the various parts of the body is dark, impure blood. In
the lungs this dark blood is spread out in very minute capillaries and
exposed to the air. While passing through the capillaries of the lungs,
the blood gives up some of its impurities in exchange for oxygen from
the air. The red corpuscles absorb the oxygen and the color of the blood
changes from dark purple to bright red again. The purified blood is then
carried back to the upper chamber of the left side of the heart through
four large veins. The blood is now ready to begin another journey around
the body.

~11. The Pulse.~--If you place your finger on your wrist at just the
right spot, you can feel a slight beating. This beating is called the
_pulse_. It is caused by the movement of the blood in the artery of the
wrist at each beat of the heart. The pulse can be felt at the neck and
in other parts of the body where an artery comes near to the surface.

~12. How much Work the Heart Does.~--The heart is a small organ, only
about as large as your fist, and yet it does an amount of work which is
almost beyond belief. Each time it beats, it does as much work as your
arm would do in lifting a large apple from the ground to your mouth. It
beats when we are asleep as well as when we are awake. When we run we
know by the way in which it beats that it is working very fast. Do you
know how much a ton is? Well, in twenty-four hours the heart does as
much work as a man would do in lifting stones enough to weigh more than
one hundred and twenty tons.

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

~14. The Lymph.~--In the lymph channels the white corpuscles float in a
colorless fluid called _lymph_. The lymph is composed of the fluid
portion of the blood which has soaked through the walls of the small
vessels. The chief purpose of the lymphatics is to carry the lymph from
the tissues back to the heart.

~15. Lymphatic Glands.~--Here and there, scattered through the body, are
oval structures into each of which many lymphatic vessels are found to
run, as shown in the illustration. These are called _lymphatic glands_.

[Illustration: LYMPH GLAND AND VESSELS.]

~16.~ The heart and blood-vessels are among the most wonderful
structures in the body. It is no wonder, then, that alcohol, tobacco,
and other narcotics and stimulants produce their most deadly effects
upon these delicate organs. What these effects are we shall learn more
fully in the next chapter.


SUMMARY.

1. The heart beats to circulate the blood.

2. The heart has four chambers, two upper and two lower.

3. There are tubes called blood-vessels which carry the blood to all
parts of the body.

4. These tubes are connected with the heart.

5. The vessels which carry blood away from the heart are called
arteries, and those which carry blood back to the heart are called
veins.

6. The arteries and veins are connected by small tubes called
capillaries.

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

8. The color of the blood changes from red to blue in going through the
capillaries. The change is due to the loss of oxygen.

9. In the circulation of the lungs, the blood in the arteries is blue,
that in the veins, red.

10. The change from blue to red takes place while the blood is passing
through the capillaries of the lungs. The change is due to the oxygen
which the corpuscles of the blood take up in the lungs.

11. The pulse is caused by the beating of the heart.

12. The heart does a great deal of work every day in forcing the blood
into different parts of the body.

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

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

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

16. The object of the lymphatics is to remove from the tissues and
return to the general circulation the lymph and white blood corpuscles
which escape through the walls of the capillaries.




CHAPTER XII.

HOW TO KEEP THE HEART AND THE BLOOD HEALTHY.


~1.~ The heart is one of the most important of all the organs of the
body. If we take good care of it, it will do good service for us during
a long life. Let us notice some ways in which the heart is likely to be
injured.

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

~3. Effects of Bad Air.~--Bad air is very harmful to the heart and to
the blood also. We should always remember that the blood of the body
while passing through the lungs is exposed to the air which we breathe.
If the air is impure, the blood will be poisoned. In churches and in
other places where the air becomes foul, people often faint from the
effects of the impure air upon the heart. It is important that the air
of the rooms in which we live and sleep should be kept very pure by good
ventilation.

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

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

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

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

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

~9. Effects of Alcohol upon the Blood.~--If you should take a drop of
blood upon your finger, and put it under the microscope, and then add a
little alcohol to it, you would see that the corpuscles would be quickly
destroyed. In a few seconds they would be so shrivelled up that no one
could tell that they had ever been the beautiful little corpuscles which
are so necessary to health. When alcohol is taken as a drink, it does
not destroy the corpuscles so quickly, but it injures them so that they
are not able to do their work of absorbing and carrying oxygen well.
This is one reason why the faces of men who use alcoholic drinks often
look so blue.

~10. Alcohol Overworks the Heart.~--Dr. Parkes, a very learned English
physician, took the pains to observe carefully the effects of alcohol
upon the heart of a soldier who was addicted to the use of liquor. He
counted the beats of the soldier's pulse when he was sober; and then
counted them again when he was using alcohol, and found that when the
soldier took a pint of gin a day his heart was obliged to do one fourth
more work than it ought to do.

~11. Effects of Alcohol upon the Blood-Vessels.~--If you put your hands
into warm water, they soon become red. This is because the blood-vessels
of the skin become enlarged by the heat, so that they hold more blood.
Alcohol causes the blood to come to the surface in the same way. It is
this that causes the flushed cheeks and the red eyes of the drunkard.
Sometimes, after a man has been using alcohol a long time, the
blood-vessels of his face remain enlarged all the time. This makes his
nose grow too fast, and so in time it gets too large, and then he has a
rum-blossom.

~12. Effects of Tobacco on the Heart and the Blood.~--When a boy first
tries to use tobacco, it makes him feel very sick. If you should feel
his pulse just then, you would find it very weak. This means that the
heart is almost paralyzed by the powerful poison of the tobacco. Tobacco
also injures the blood corpuscles.

~13.~ _Tea_ and _coffee_ also do their share of mischief to the heart.
Those who use them very strong often complain of palpitation, or heavy
and irregular beating of the heart.

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

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

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

~17. How to Stop the Bleeding of Wounds.~--If the bleeding vessel is an
artery, apply pressure on the side of the wound next to the heart. If
the bleeding is from a vein, apply it on the opposite side. It is
generally best to apply pressure directly over the wound or on both
sides. The pressure can be made with the thumbs or with the whole hand.
Grasp the part firmly and press very hard, or tie a handkerchief or
towel around the wounded part and twist it very tight. If an arm or limb
is the part injured, the person should be made to lie down, and the
injured part should be held up. This is of itself an excellent means of
stopping hemorrhage.

~18. Nose-Bleed.~--For nose-bleed a very good remedy is holding one or
both hands above the head. The head should be held up instead of being
bent forward, and the corner of a dry handkerchief should be pressed
into the bleeding nostril. It is well to bathe the face with very hot
water, and to snuff hot water into the nostril if the bleeding is very
severe. If the bleeding is very bad or is not readily stopped, a
physician should be called.


SUMMARY.

1. Violent exercise is likely to injure the heart.

2. Bad air makes the blood impure and disturbs the action of the heart.

3. Unwholesome food produces bad blood.

4. Too little sleep makes the blood poor.

5. Proper clothing is necessary to make the blood circulate equally in
different parts of the body.

6. Violent anger may cause death by stopping the beating of the heart.

7. Alcohol injures the blood.

8. Alcohol overworks the heart.

9. Alcohol enlarges the blood-vessels.

10. Tobacco injures the blood.

11. Tobacco weakens the heart and makes the pulse irregular.

12. The use of strong tea and coffee causes palpitation of the heart.

13. A cold is caused by a disturbance of the circulation. A cold should
never be neglected.

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

15. When a vein is wounded, the blood is purple and flows in a steady
    stream.

16. To stop bleeding from an artery, press on the side of the wound
towards the heart, or on both sides of the wound.

17. When a vein is wounded, press on the side away from the heart.




CHAPTER XIII.

WHY AND HOW WE BREATHE.


~1. An Experiment.~--Let us perform a little experiment. We must have a
small bit of candle, a fruit jar, or a bottle with a large mouth, and a
piece of wire about a foot long. Let us notice carefully what we are
about to do and what happens.

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

~3.~ What do you think is the reason that the candle will not burn when
shut up in a bottle? A candle uses air when it burns. If shut up in a
small, tight place, it soon uses up so much air that it can burn no
longer. Try the experiment again, and when the candle begins to burn
dimly, take it out quickly. We see that at once the light burns bright
again.

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

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

~6. Oxygen.~--The reason why animals need air, and why the fire will not
burn without it, is that the air contains _oxygen_, and it is the oxygen
of the air which burns the wood or coal and produces heat. So it is the
oxygen that burns in our bodies and keeps us warm.

~7.~ When wood and coal are burned, heat is produced; but some parts of
the fuel are not made into heat. While the fire burns, smoke escapes
through the pipe or chimney; but a part of the fuel remains in the stove
in the form of ashes. Smoke and ashes are the waste parts of the fuel.

~8. Poison in the Breath.~--The burning which takes place in our bodies
produces something similar to the smoke and ashes produced by the fire
in a stove. The smoke is called _carbonic-acid gas_,[A] an invisible
vapor, and escapes through the lungs. The ashes are various waste and
poisonous matters which are formed in all parts of the body. These waste
matters are carried out of the body through the skin, the kidneys, the
liver, and other organs.

~9. Another Experiment.~--We cannot see the gas escape from our lungs,
but we can make an experiment which will show us that it really does
pass out. Get two drinking-glasses and a tube. A glass tube is best, but
a straw will do very well. Put a little pure water into one glass and
the same quantity of lime-water into the other glass. Now put one end of
the tube into the mouth and place the other end in the pure water.
Breathe through the tube a few times. Look at the water in the glass and
see that no change has taken place. Now breathe through the lime-water
in the same way. After breathing two or three times, you will notice
that the lime-water begins to look milky. In a short time it becomes
almost as white as milk. This is because the lime-water catches the
carbonic-acid gas which escapes from our lungs with each breath, while
the pure water does not.

~10. Why we Breathe.~--By this experiment we learn another reason why
we breathe. We must breathe to get rid of the carbonic-acid gas, which
is brought to the lungs by the blood to be exchanged for oxygen. There
are two reasons then why we breathe: (_a_) to obtain oxygen; (_b_) to
get rid of carbonic-acid gas.

~11. How a Frog Breathes.~--Did you ever see a frog breathe? If not,
improve the first opportunity to do so. You will see that the frog has a
very curious way of breathing. He comes to the top of the water, puts
his nose out a little, and then drinks the air. You can watch his throat
and see him swallowing the air, a mouthful at a time, just as you would
drink water.

~12.~ If you had a chance to see the inside of a frog you would find
there a queer-shaped bag. This is his air-bag. This bag has a tube
running up to the throat. When the frog comes to the surface of the
water he fills this bag with air. Then he can dive down into the mud out
of sight until he has used up the supply of air. When the air has been
changed to carbonic-acid gas, he must come to the surface to empty his
air-bag and drink it full again.

~13. The Lungs.~--We do not drink air as the frog does, but like the
frog we have an air-bag in our bodies. Our air-bag has to be emptied
and filled so often that we cannot live under water long at a time, as
a frog does. We call this air-bag the lungs. We have learned before that
the lungs are in the chest. We need so much air and have to change the
air in our lungs so often that we would not have time to swallow it as a
frog does. So nature has made for us a breathing apparatus of such a
kind that we can work it like a pair of bellows. Let us now study our
breathing-bellows and learn how they do their work.

~14. The Windpipe and Air-tubes.~--A large tube called the _windpipe_
extends from the root of the tongue down the middle of the chest. The
windpipe divides into two main branches, which subdivide again and
again, until the finest branches are not larger than a sewing-needle.
The branches are called _bronchial tubes_. At the end of each tube is a
cluster of small cavities called _air-cells_. The air-tubes and
air-cells are well shown on the following page.

~15. The Voice-box.~--If you will place the ends of your fingers upon
your throat just above the breast-bone, you will feel the windpipe, and
may notice the ridges upon it. These are rings of cartilage, a hard
substance commonly called gristle. The purpose of these rings is to keep
the windpipe open. Close under the chin you can find something which
feels like a lump, and which moves up and down when you swallow.

[Illustration: AIR-TUBES AND AIR-CELLS.]

This is a little box made of cartilage, called the voice-box, because by
means of this curious little apparatus we are able to talk and sing. Two
little white bands are stretched across the inside of the voice-box.
When we speak, these bands vibrate just as do the strings of the piano.
These bands are called the _vocal cords_.

~16. The Epiglottis.~--At the top of the voice-box is placed a curious
trap-door which can be shut down so as to close the entrance to the
air-passages of the lungs. This little door has a name rather hard to
remember. It is called the _epiglottis_ (ep-i-glot´-tis). The cover of
the voice-box closes whenever we swallow anything. This keeps food or
liquids from entering the air passages. If we eat or drink too fast the
voice-box will not have time to close its little door and prevent our
being choked. Persons have been choked to death by trying to swallow
their food too fast. Do you not think this is a very wonderful door that
can open and shut just when it should do so without our thinking
anything about it?

~17. The Nostrils and the Soft Palate.~--The air finds its way to the
lungs through the mouth or through the two openings in the nose called
the _nostrils_. From each nostril, three small passages lead backward
through the nose. At the back part of the nasal cavity the passages of
the two sides of the nose come together in an open space, just behind
the soft curtain which hangs down at the back part of the mouth. This
curtain is called the _soft palate_. Through the opening behind this
curtain the air passes down into the voice-box and then into the lungs.

~18. The Pleura.~--In the chest the air tubes and lung of each side are
enclosed in a very thin covering, called the _pleura_. The cavity of the
chest in which the lungs are suspended is also lined by the pleura. A
limpid fluid exudes from the pleura which keeps it moist, so that when
the two surfaces rub together, as the lungs move, they do not become
chafed and irritated.

~19. Walls of the Chest.~--The ribs form a part of the framework of the
chest. The ribs are elastic. The spaces between them are filled up with
muscles, some of which draw the ribs together, while others draw them
apart. Can you tell any reason why the walls of the chest are elastic?
The lower wall or floor of the chest cavity is formed by a muscle called
the _diaphragm_, which divides the trunk into two cavities, the chest
and the abdomen.

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

~21.~ It is in just this way that we breathe. When we are about to take
a long breath, the muscles pull upon the sides of the chest in such a
way as to draw them apart. At the same time the diaphragm draws itself
downward. By these means, the cavity of the chest is made larger and air
rushes in through the nose or mouth to fill the space. When the muscles
stop pulling, the walls of the chest fall back again to their usual
position and the diaphragm rises. The cavity of the chest then becomes
smaller and the air is forced out through the nose or mouth. This
process is repeated every time we breathe.

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

~23. How Much the Lungs Hold.~--Every time we breathe, we take into our
lungs about two thirds of a pint of air and breathe out the same
quantity. Our lungs hold, however, very much more than this amount. A
man, after he has taken a full breath, can breathe out a gallon of air,
or more than ten times the usual amount. After he has breathed out all
he can, there is still almost half a gallon of air in his lungs which he
cannot breathe out. So you see the lungs hold almost a gallon and a half
of air.

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

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

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

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

~28. How the Air is Purified.~--Perhaps it occurs to you that with so
many people and animals breathing all the while, the air would after a
time become so filled with carbonic-acid gas that it would be unfit to
breathe. This is prevented by a wonderful arrangement of Nature. The
carbonic-acid gas which is so poisonous to us is one of the most
necessary foods for plants. Plants take in carbonic-acid gas through
their leaves, and send the oxygen back into the air ready for us to use
again.

~29.~ We have already learned that the oxygen taken in by the lungs is
carried to the various parts of the body by the little blood corpuscles.
The effect of strong liquors is to injure these corpuscles so that they
cannot carry so much oxygen as they ought to do. For this reason, the
blood of a drunkard is darker in color than that of a temperate person,
and contains more carbonic-acid gas. The drunkard's lungs may supply all
the air he needs, but his blood has been so damaged that he cannot use
it. Excessive smoking has a similar effect.


SUMMARY.

1. Our bodies need air, just as a candle or a fire does.

2. A small animal shut up in a close jar soon dies for want of air. We
need the oxygen which the air contains.

3. Oxygen causes a sort of burning in our bodies.

4. The burning in our bodies keeps us warm, and destroys some of the
waste matters.

5. The breathing organs are the windpipe and bronchial tubes, the
voice-box, the epiglottis, the nostrils, the soft palate, the lungs, the
air-cells, the pleura, the diaphragm, and the chest walls.

6. When we breathe we use our lungs like a pair of bellows.

7. A man's lungs hold nearly one and a half gallons of air.

8. In ordinary breathing we use less than a pint of air, but when
   necessary we can use much more.

9. The air we breathe out contains carbonic-acid gas and another
invisible poison.

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

11. The lungs purify the blood. While passing through the lungs, the
color of the blood changes from purple to bright red.

12. Plants purify the air by removing the carbonic-acid gas.

13. Alcohol and tobacco injure the blood corpuscles so that they cannot
take up the oxygen from the air which the lungs receive.




CHAPTER XIV.

HOW TO KEEP THE LUNGS HEALTHY.


~1. Pure Air Necessary.~--A person may go without eating for a month, or
without drinking for several days, and still live; but a strong man will
die in a few moments if deprived of air. It is very important that we
breathe plenty of pure air. There are many ways in which the air becomes
impure.

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

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

~4. Contagious Diseases.~--You have heard about diphtheria and scarlet
fever and measles, and other "catching diseases." When a person is sick
with one of these diseases, the air about him is poisoned with germs or
something similar, which may give the same disease to other persons who
inhale it. So when a person is sick from one of these diseases, it is
very important that he should be put in a room by himself and shut away
from every one but the doctor and the nurse. It is also necessary that
all the clothing and bedding used by the sick person, and everything in
the room, as well as the room itself, should be carefully cleansed and
disinfected when the person has recovered, so as to wipe out every trace
of the disease. The writer has known many cases in which persons who
have been sick with some of these diseases were careless and gave the
disease to others who died of it, although they themselves recovered. Do
you not think it very wrong for a person to give to another through
carelessness a disease which may cause his death?

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

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

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

~8.~ Many people ventilate their houses by opening the doors and
windows. This is a very good way of ventilating a house in warm weather,
but is a very poor way in cold weather, as it causes cold draughts, and
makes the floor cold, so that it is difficult to keep the feet warm. It
is much better to have the air warmed by a furnace or some similar
means, before it enters the rooms. There ought also to be in each room a
register to take the foul air out, so that it will not be necessary to
open the windows. This register should be placed at the floor, because
when the pure air enters the room warm, it first rises to the upper part
of the room, and then as it cools and at the same time becomes impure,
it settles to the floor, where it should be taken out by the register.

~9. How to Breathe.~--We should always take pains to expand the lungs
well in breathing, and to use the entire chest, both the upper and the
lower part. Clothing should be worn in such a way that every portion of
the chest can be expanded. For this reason it is very wrong to wear the
clothing tight about the waist. Clothing so worn is likely to cause the
lungs to become diseased.

~10. Bad Habits.~--Students are very apt to make themselves flat-chested
and round-shouldered by leaning over their desks while writing or
studying. This is very harmful. We should always use great care to sit
erect and to draw the shoulders well back. Then, if we take pains to
fill the lungs well a great many times every day, we shall form the
habit of expanding the lungs, and shall breathe deeper, even when we are
not thinking about doing so.

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

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

~13.~ Many people suppose that the use of alcohol will save a man from
consumption. This is not true. A man may become a drunkard by the use of
alcohol, and yet he is more likely to have consumption than he would
have been if he had been a total abstainer. "Drunkard's consumption" is
one of the most dreadful forms of this disease.


SUMMARY.

1. Pure air is as necessary as food and drink.

2. Anything which is rotting or undergoing decay causes a bad odor, and
thus makes the air impure.

3. Foul air contains germs which cause disease and often death.

4. Persons sick with "catching" diseases should be carefully avoided.
Such persons should be shut away from those who are well, and their
rooms and clothing should be carefully cleansed and disinfected.

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

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

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

8. The clothing about the chest and waist should be loose, so that the
lungs may have room to expand.

9. Always breathe through the nose.

10. Tobacco causes disease of the throat and nose.

11. Alcohol causes consumption and other diseases of the lungs.




CHAPTER XV.

THE SKIN AND WHAT IT DOES.


~1. The Skin.~--The skin is the covering of the body. It fits so exactly
that it has the precise shape of the body, like a closely fitting
garment. If you will take up a little fold of the skin you will see that
it can be stretched like a piece of india-rubber. Like rubber, when it
is released it quickly contracts and appears as before.

~2. The Bark of Trees.~--Did you ever peel the bark off of a young tree?
If so, you have noticed that there were really two barks, an outer bark,
as thin as paper, through which you could almost see, and an inner and
much thicker bark, which lay next to the wood of the tree. You can peel
the outer bark off without doing the tree much harm. Indeed, if you will
notice some of the fruit or shade trees in the yard, at home, you will
see that the outer bark of the tree peels itself off, a little at a
time, and that new bark grows in its place. If you tear off the inner
bark, however, it will injure the tree. It will make it bleed, or cause
the sap to run. The sap is the blood of the tree. The bark is the skin
of the tree. When the bare place heals over, an ugly scar will be left.

~3. The Cuticle.~--Our bodies, like trees, have two skins, or really one
skin with an outer and an inner layer. When a person burns himself so as
to make a blister, the outer skin, called the _cuticle_, is separated
from the inner by a quantity of water or serum poured out from the
blood. This causes the blister to rise above the surrounding skin. If
you puncture the blister the water runs out. Now we may easily remove
the cuticle and examine it. The cuticle, we shall find, looks very much
like the skin which lines the inside of an egg-shell, and it is almost
as thin.

~4.~ The cuticle is very thin in most parts of the body, but in some
places, as the palms of the hands and the soles of the feet, it is quite
thick. This is because these parts of the skin come in contact with
objects in such a way as to be liable to injury if not thus protected.
The cuticle has no blood-vessels and very few nerves. With a fine needle
and thread you can easily take a stitch in it without making it bleed or
causing any pain.

~5. The Pigment.~--The under side of the cuticle is colored by little
particles of pigment or coloring matter. The color of this pigment
differs in different races. In the negro, the color of the pigment is
black. In some races the pigment is brown. In white persons there is
very little pigment, and in some persons, called albinos, there is none
at all.

~6. The Inner or True Skin.~--The inner skin, like the inner bark of a
tree, is much thicker than the outer skin. It is much more important,
and for this reason is sometimes called the _true skin_. It contains
nerves and blood-vessels.

[Illustration: SKIN OF PALM OF HAND MAGNIFIED.]

~7. The Sweat Glands.~--If you look at the palm of the hand you will see
many coarse lines, and by looking much closer you will see that the palm
is completely covered with very fine ridges and furrows. Now, if you
examine these ridges with a magnifying-glass, you will find arranged
along each ridge a number of little dark spots. Each of these points is
the mouth of a very small tube. This is called a _sweat duct_. These
ducts run down through both the outer and inner layers of the skin. At
the under side of the true skin the end of the tube is rolled up in a
coil, as you can see by looking at the illustration on the following
page. The coiled parts of the tubes are called _sweat glands_, because
they separate from the blood the fluid which we call sweat or
perspiration.

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

[Illustration: THE STRUCTURE OF THE SKIN.]

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

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

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

~12. The Nails.~--The nails of the fingers and the toes grow out of
little pockets in the skin just as the hairs do. Both the hair and the
nails are really parts of the outer skin, which is curiously changed and
hardened. The nails lie upon the surface of the true skin and grow from
the under side as well as from the little fold of skin at the root of
the nail. They are made to give firmness and protection to the ends of
the fingers and toes. The nails of the fingers are also useful in
picking up small objects and in many other ways.

~13. Uses of the Skin.~--The skin is useful in several ways:

(1) _It Removes Waste._--The sweat glands and ducts are constantly at
work removing from the blood particles which have been worn out and can
be of no further use. If we get very warm, or if we run or work very
hard, the skin becomes wet with sweat. In a little while, if we stop to
rest, the sweat is all gone. What becomes of it? You say it dries up,
which means that it has passed off into the air. Sweating is going on
all the time, but we do not sweat so much when we are quiet and are not
too warm, and so the sweat dries up as fast as it is produced, and we do
not see it. Nearly a quart of sweat escapes from the skin daily.

(2) _Breathing through the Skin._--We breathe to a slight extent through
the skin. There are some lower animals which breathe with their skins
altogether. A frog can breathe with its skin so well that it can live
for some time after its lungs have been removed. Breathing is an
important part of the work of the skin, and we should be careful, by
keeping it clean and healthy, to give it a good chance to breathe all
that it can.

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

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

(5) _The Skin Protects the Body._--The skin is a natural clothing which
protects us much better than any other kind of clothing could. It is so
soft and pliable that it cannot hurt the most delicate part which it
covers, yet it is very strong and tough.


SUMMARY.

1. The skin is the covering of the body. It has two layers, the outer,
called the cuticle, and the inner, called the true skin.

2. A substance called pigment is found between the two skins. This gives
the skin its color.

3. The true skin has blood-vessels and nerves, but the cuticle has no
blood-vessels and very few nerves.

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

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

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

7. The skin is a very useful organ. It removes waste matters, it
breathes, it absorbs, it has feeling, and it protects the body.




CHAPTER XVI.

HOW TO TAKE CARE OF THE SKIN.


~1. Uses of the Pores of the Skin.~--Many years ago, at a great
celebration, a little boy was covered all over with varnish and gold
leaf, so as to make him represent an angel. The little gilded boy looked
very pretty for a short time, but soon he became very sick, and in a few
hours he was dead. Can you guess what made him die? He died because the
pores of his skin were stopped up, and the sweat glands could not carry
off the poisonous matter from his body.

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

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

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

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

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

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

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

~9. Care of the Hair and the Nails.~--The scalp should be kept clean by
thorough and frequent washing and daily brushing. Hair oils are seldom
needed. If the skin of the head is kept in a healthy condition, the hair
requires no oil.

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

~11. Effects of Narcotics and Stimulants upon the Skin.~--Alcohol,
tobacco, opium, and all other narcotics and stimulants have a bad effect
upon the skin. Alcohol often causes the skin to become red and blotched,
and tobacco gives it a dingy and unhealthy appearance.


SUMMARY.

1. If the pores of the skin are closed, a person will die.

2. We should bathe often enough to keep the skin clean.

3. We should not keep our rooms too warm, and should avoid wearing too
much clothing.

4. Alcohol, tobacco, and other stimulants and narcotics injure the skin.




CHAPTER XVII.

THE KIDNEYS AND THEIR WORK.


~1. The Kidneys.~--The kidneys are among the most important organs of
the body. They are in the cavity of the abdomen, near the back-bone, up
under the lower border of the ribs. Perhaps you have seen the kidneys of
a sheep or a hog. If you have, you know very nearly how the kidneys of
our own bodies appear.

[Illustration: KIDNEY.]

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

~3. How to Keep the Kidneys Healthy.~--One way of keeping the kidneys in
good health is to drink plenty of pure water, and to avoid eating too
much meat and rich food. Pepper, mustard, and other hot sauces are very
harmful to the kidneys.

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

~5. Effects of Alcohol and Tobacco upon the Kidneys.~--A piece of beef
placed in alcohol soon becomes dry and hard, and shrivels up as though
it had been burned. The effect upon the kidneys of drinking strong
liquor is almost the same. Beer and hard cider also do the kidneys harm,
sometimes producing incurable disease of these important organs.


SUMMARY.

1. The kidneys somewhat resemble the skin in their structure and in
their work.

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

3. To keep the kidneys healthy we should drink plenty of water, avoid
irritating foods and drinks, and keep the skin in health by proper
bathing.

4. The drinking of strong liquors often causes incurable disease of the
kidneys.




CHAPTER XVIII.

OUR BONES AND THEIR USES.


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

~2. The Skeleton.~--All the bones together make up the _skeleton_. (See
page 95.) There are about two hundred bones in all. They are of many
different shapes. They vary in size from the little bones of the ear,
which are the smallest, to the upper bone of the leg, which is the
largest in the body.

~3.~ The skeleton is divided into four parts: the _skull_, the _trunk_,
the _arms_, and the _legs_. We must learn something more about the bones
of each part.

~4. The Skull.~--The _skull_ is somewhat like a shell. It is made of a
number of bones joined together in such a way as to leave a hollow place
inside to hold the brain. The front part of the skull forms the
framework of the face and the jaws. In each ear there are three curious
little bones, which aid us in hearing.

~5. The Trunk.~--The bones of the trunk are, the _ribs_, the
_breast-bone_, the _pelvis_, and the _back-bone_. The bones of the trunk
form a framework to support and protect the various organs within its
cavities.

~6. The Ribs.~--There are twelve _ribs_ on each side. The ribs join the
back-bone at the back. They are connected by cartilage to the
breast-bone in front. They look somewhat like the hoops of a barrel.
With the breast-bone and the back-bone they form a bony cage to contain
and protect the heart and the lungs.

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

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

[Illustration: SKELETON OF A MAN.]

~9. The Spinal Canal.~--Each of the separate bones that make up the
back-bone has an opening through it, and the bones are so arranged, one
above another, that the openings make a sort of canal in the back-bone.
By the connection of the spinal column to the head, this canal opens
into the cavity of the skull. Through this canal there passes a peculiar
substance called the _spinal cord_, of which we shall learn more at
another time.

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

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

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

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

~14. Cartilage.~--The ends of bones which come together to form a joint
are covered with a smooth, tough substance, which protects the bone from
wear. This is called _gristle_ or _cartilage_. You have, no doubt, seen
the gristle on the end of a "soup-bone" or on one of the bones of a
"joint of beef."

~15.~ The joint contains a fluid to oil it, so that the ends of the
bones move upon each other very easily. If the joints were dry, every
movement of the body would be very difficult and painful.

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

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

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

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

~20.~ A person's height depends upon the length of his bones. The use of
alcohol and tobacco by a growing boy has a tendency to stunt the growth
of his bones, so that they do not develop as they should.


SUMMARY.

1. There are about two hundred bones in the body.

2. All together they are called the skeleton.

  3. The skeleton is divided as follows:

  _a._ The skull.

                   { Ribs.
  _b._ The trunk.  { Breast-bone.
                   { Pelvis.
                   { Back-bone.
                   { Collar-bone.
                   { Shoulder-blade.

                   { Upper arm-bones.
 _c._ The arms.    { Lower arm-bones.
                   { Wrist.
                   { Hand and fingers.

                   { Thigh.
                   { Knee-pan.
  _d._ The legs.   { Lower-leg bones.
                   { Ankle, including heel-bone.
                   { Foot and toes.

4. The bones are useful for support, protection, and motion.

5. The place where two bones join is called a joint.

6. The tough substance which covers the ends of many bones is called
cartilage or gristle.

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

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

9. Bones are about two thirds earthy matter and one third animal matter.

10. The use of alcohol and tobacco may prevent proper development of the
bones.




CHAPTER XIX.

HOW TO KEEP THE BONES HEALTHY.


~1. Composition of the Bones.~--Our bones, like the rest of our bodies,
are made of what we eat. If our food does not contain enough of the
substances which are needed to make healthy bone, the bones will become
unhealthy. They may be too soft and become bent or otherwise misshapen.
This is one of the reasons why bread made from the whole grain is so
much more healthful than that made from very fine white flour. In making
fine white flour the miller takes out the very best part of the grain,
just what is needed to make strong and healthy bones. Oatmeal is a very
good food for making healthy bones.

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

~3. Improper Positions.~--The bones are so soft and flexible when we
are young that they are very easily bent out of shape if we allow
ourselves to take improper positions in sitting, lying, or standing.
This is the way in which flat and hollow chests, uneven shoulders,
curved spines, and many other deformities are caused.

[Illustration: IMPROPER POSITION.]

~4.~ In sitting, standing, and walking, we should always take care to
keep the shoulders well back and the chest well expanded, so that we may
not grow misshapen and deformed. Many boys and girls have ugly curves in
their backbones which have been caused by sitting at high desks with one
elbow on the desk, thus raising the shoulder of that side so high that
the spine becomes crooked. The illustrations on this and the following
page show good and bad positions and also the effects of bad positions.

[Illustration: PROPER POSITION.]

~5. Seats and Desks.~--The seats and desks of school-children should be
of proper height. The seats should be low enough to allow the feet to
rest easily upon the floor, but not too low. The desk should be of such
a height that, in writing, one shoulder will not be raised above the
other. If a young person bends the body forward, he will, after a time,
become round-shouldered and his chest will become so flattened that the
lungs cannot be well expanded.

[Illustration: DESK TOO HIGH.]

~6.~ Standing on one foot, sitting bent forward when reading or at work,
sleeping with the head raised high upon a thick pillow or bolster, are
ways in which young persons often grow out of shape.

[Illustration: SEAT TOO HIGH.]

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

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

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

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

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

~12.~ When a man uses alcohol and tobacco, their effects upon the bones
are not so apparent as are the effects upon the blood, the nerves, and
other organs; but when the poisonous drugs are used by a growing boy,
their damaging influence is very plainly seen. A boy who smokes cigars
or cigarettes, or who uses strong alcoholic liquors, is likely to be so
stunted that even his bones will not grow of a proper length and he will
become dwarfed or deformed.


SUMMARY.

1. To keep the bones healthy they must have plenty of healthful food.

2. The whole-grain preparations furnish the best food for the bones.

3. Walking at too early an age often makes the legs crooked.

4. Hard work at too early an age stunts the growth.

5. Bad positions and tight or poorly-fitting clothing are common causes
of flat chests, round shoulders, and other deformities.

6. Tight or high-heeled shoes deform the feet and make the gait awkward.

7. The bones may be easily broken or put out of joint, or the ligaments
may be torn by rough play.

8. Alcohol prevents healthy growth.




CHAPTER XX.

THE MUSCLES AND HOW WE USE THEM.


~1. The Muscles.~--Where do people obtain the beefsteak and the
mutton-chops which they eat for breakfast? From the butcher, you will
say; and the butcher gets them from the sheep and cattle which he kills.
If you will clasp your arm you will notice that the bones are covered by
a soft substance, the flesh. When the skin of an animal has been taken
off, we can see that some of the flesh is white or yellow and some of it
is red. The white or yellow flesh is fat. The red flesh is lean meat,
and it is composed of muscles.

~2. The Number of Muscles.~--We have about five hundred different
muscles in the body. They are arranged in such a way as to cover the
bones and make the body round and beautiful. They are of different forms
and sizes.

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

~4. How a Muscle is Formed.~--If you will examine a piece of corned or
salted beef which has been well boiled, you will notice that it seems to
be made up of bundles of small fibres or threads of flesh. With a little
care you can pick one of the small fibres into fine threads. Now, if you
look at one of these under a microscope you find that it is made of
still finer fibres, which are much smaller than the threads of a
spider's web. One of these smallest threads is called a _muscular
fibre_. Many thousands of muscular fibres are required to make a muscle.

[Illustration: MUSCULAR FIBRES.]

~5.~ Most of the muscles are made fast to the bones. Generally, one end
is attached to one bone, and the other to another bone. Sometimes one
end is made fast to a bone and the other to the skin or to other
muscles.

~6. The Tendons.~--Many of the muscles are not joined to the bones
directly, but are made fast to them by means of firm cords called
_tendons_. If you will place the thumb of your left hand upon the wrist
of the right hand, and then work the fingers of the right hand, you may
feel these cords moving underneath the skin.

~7. What the Muscles Do.~--With the left hand grasp the right arm just
in front of the elbow. Now shut the right hand tightly. Now open it.
Repeat several times. The left hand feels something moving in the flesh.
The motion is caused by the working of the muscles, which shorten and
harden when they act.

~8.~ All the movements of the body are made by means of muscles. When we
move our hands, even when we close the mouth or the eyes, or make a wry
face, we use the muscles. We could not speak, laugh, sing, or breathe
without muscles.

~9. Self-acting Muscles.~--Did you ever have a fit of sneezing or
hiccoughing? If you ever did, very likely you tried hard to stop but
could not. Do you know why one cannot always stop sneezing or
hiccoughing when he desires to do so? It is because there are certain
muscles in the body which do not act simply when we wish them to act,
but when it is necessary that they should. The muscles which act when we
sneeze or hiccough are of this kind. The arm and the hand do not act
unless we wish them to do so. Suppose it were the same with the heart.
We should have to stay awake all the while to keep it going, because it
would not act when we were asleep. The same is true of our breathing. We
breathe when we are asleep as well as when we are awake, because the
breathing muscles work even when we do not think about them.

~10.~ The stomach, the intestines, the blood-vessels, and many other
organs within the body have this kind of muscles. The work of these
self-acting muscles is very wonderful indeed. Without it we could not
live a moment. This knowledge should lead us to consider how dependent
we are, each moment of our lives, upon the delicate machinery by which
the most important work of our bodies is performed, and how particular
we should be to keep it in good order by taking proper care of
ourselves.


SUMMARY.

1. The flesh, or lean meat, is composed of muscles.

2. There are five hundred muscles in the body.

3. Muscles are composed of many small threads called muscular fibres.

4. Many of the muscles are joined to the bones by strong white cords
called tendons.

5. Muscular fibres can contract so as to lessen their length. It is in
this way that the muscles perform their work.

6. All bodily motions are due to the action of the muscles.

7. Most of the muscles act only when we wish them to do so. Some
muscles, however, act when it is necessary for them to do so, whether we
will that they should act or not, and when we are asleep as well as when
we are awake.




CHAPTER XXI.

HOW TO KEEP THE MUSCLES HEALTHY.


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

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

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

~4. Food and Strength.~--A great part of our food goes to nourish the
muscles. Some foods make us strong, while others do not. Plain foods,
such as bread, meat, potatoes, and milk, are good for the muscles; but
cakes and pies, and things which are not food, such as mustard, pepper,
and spices, do not give us strength, and are likely to do us harm.

~5. Over-Exertion.~--We ought not to exert ourselves too much in lifting
heavy weights, or trying to do things which are too hard for us.
Sometimes the muscles are permanently injured in this way.

~6. The Clothing.~--We ought not to wear our clothing so tight as to
press hard upon any part of the body. If we do, it will cause the
muscles of that part to become weak. If the clothing is worn tight about
the waist, great mischief is often done. The lungs cannot expand
properly, the stomach and liver are pressed out of shape, and the
internal organs are crowded out of their proper places.

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

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

[Illustration: FOOT OF CHINESE WOMAN.]

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

~10. Effects of Drunkenness.~--When a man has become addicted to strong
drink, his muscles become partly paralyzed, so that he cannot walk as
steadily or speak as readily or as clearly as before. His fingers are
clumsy, and his movements uncertain. If he is an artist or a jeweller,
he cannot do as fine work as when he is sober. When a man gets very
drunk, he is for a time completely paralyzed, so that he cannot walk or
move, and seems almost like a dead man.

~11.~ If you had a good horse that had carried you a long way in a
carriage, and you wanted to travel farther, what would you do if the
horse were so tired that he kept stopping in the road? Would you let him
rest and give him some water to drink and some nice hay and oats to eat,
or would you strike him hard with a whip to make him go faster? If you
should whip him he would act as though he were not tired at all, but do
you think the whip would make him strong, as rest and hay and oats
would?

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

~13.~ When you grow up to be men and women you will want to have strong
muscles. So you must be careful not to give alcohol a chance to injure
them. If you never taste it in any form you will be sure to suffer no
harm from it.

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

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

~16. Tea and Coffee.~--Strong tea and coffee, while by no means so bad
as alcohol and tobacco, may make us weak and sick. A person who drinks
strong tea or coffee feels less tired while at work than if he had not
taken it, but he is more tired afterwards. So you see that tea and
coffee are also whips, small whips we might call them, and yet they
really act in the same way as do other narcotics and stimulants. They
make a person feel stronger than he really is, and thus he is led to use
more strength than he can afford to do.


SUMMARY.

1. We must use the muscles to make them grow large and strong.

2. Exercise should be taken regularly.

3. Exercise makes the muscles strong, the body beautiful, the lungs
active, the heart vigorous, and the whole body healthy.

4. Things we ought not to do: To run or play hard just before or after
eating; to strain our muscles by lifting too heavy weights; to exercise
so violently as to get out of breath; to lie, sit, stand, or walk in a
cramped position, or awkward manner; to wear the clothing so tight as to
press hard upon the muscles.

5. Good food is necessary to make the muscles strong and healthy.

6. Alcohol makes the muscles weak, although at first it makes us feel
stronger.

7. A boy who uses tobacco will not grow as strong and well as one who
does not.

8. The use of strong tea and coffee may injure the muscles.




CHAPTER XXII.

HOW WE FEEL AND THINK.


~1. How we Think.~--With what part of the body do we think? You will at
once say that we think with the head; but we do not think with the whole
head. Some parts of the head we use for other purposes, as the mouth to
eat and speak with, and the nose to smell and breathe with. The part we
think with is inside of the skull, safely placed in a little room at the
top and back part of the head. Do you remember the name of this organ
which fills the hollow place inside of the skull? We learned some time
ago that it is called the _brain_. It is with the brain that we study
and remember and reason. So the brain is one of the most important
organs in our body, and we must try to learn all we can about it.

~2. The Brain.~--You cannot see and examine your own brain because it is
shut up in the skull; but perhaps you can find the brain of a sheep or a
calf at the meat market. The brain of one of these animals looks very
nearly like your own.

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

[Illustration: THE BRAIN.]

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

[Illustration: BRAIN CELLS.]

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

~6.~ The long branches are such slender threads that a great number of
them together would not be as large as a fine silk thread. A great many
of these fine nerve threads are bound up in little bundles which look
like white cords. These are called _nerves_.

~7.~ The nerves branch out from the brain through openings in the skull,
and go to every part of the body. Every little muscle fibre, the heart,
the stomach, the lungs, the liver, even the bones--all have nerves
coming to them from the brain. So you see that the brain is not wholly
shut up in the skull, because its cells have slender branches running
into all parts of the body; and thus the brain itself is really in every
part of the body, though we usually speak of it as being entirely in the
skull.

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

[Illustration: BRAIN AND SPINAL CORD.]

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

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

~11. The Use of Pain.~--It is not pleasant for us to have pain, but if
the nerves gave us no pain when we are hurt we might get our limbs
burned or frozen and know nothing about it until too late to save them.

~12. Nerves of Feeling.~--We have different kinds of nerves of feeling.
Those we have learned about feel pain. Others feel objects. If you take
a marble or a pencil in the hand you know what it is by the feeling of
the object. This kind of feeling is called the sense of touch.

~13.~ There are other nerves of feeling by means of which we are able to
hear, see, taste, and smell, of which we shall learn in another lesson.
Besides these we have nerves which tell us whether objects are cold or
hot, and heavy or light. Nerves of feeling also tell us when we are
hungry, or thirsty, or tired, and when we need more air to breathe.

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

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

~16. How we Use the Nerves.~--If you happen to touch your hand to a hot
stove, what takes place? You will say that your arm pulls the hand away.
Do you know why? Let us see. The nerves of feeling in the hand tell the
nerve cells in the brain from which they come that the hand is being
burned. The cells which feel cannot do anything for the hand, but some
of their branches run over to another part of the brain, which sends
nerves down to the muscles of the arm. These cells, through their nerve
branches, cause the muscles to contract. The cells of feeling ask the
cells which have charge of the muscles to make the muscles of the arm
pull the hand away, which they do very quickly.

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

~18. An Experiment.~--A man once tried an experiment which seemed very
cruel. He took a dove and cut open its skull and took out its large
brain. What do you think the effect was? The dove did not die at once,
as you would expect. It lived for some time, but it did not know
anything. It did not know when it was hungry, and would not eat or drink
unless the food or water was placed in its mouth. If a man gets a blow
on his head, so hard as to break his skull, the large brain is often
hurt so badly that its cells cannot work, and so the man is in the same
condition as the poor dove. He does not know anything. He cannot think
or talk, and lies as though he were asleep.

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

~20. What the Little Brain Does.~--The little brain[B] thinks too, but
it does not do the same kind of thinking as the large brain. We may use
our arms and legs and many other parts when we wish to do so; and if we
do not care to use them we may allow them to remain quiet. This is not
the case with some other organs. It is necessary, for example, that the
heart, the lungs, and many other organs of the body should keep at work
all the time. If the large brain had to attend to all of these
different kinds of work besides thinking about what we see, hear, and
read, and other things which we do, it would have too much work to do,
and would not be able to do it all well. Besides, the large brain
sometimes falls asleep. So the large brain lets the little brain do the
kinds of work which have to be attended to all the time, and the little
brain keeps steadily at work when we are asleep as well as when we are
awake.

~21. What the Spinal Cord Does.~--If you tickle a person's foot when he
is asleep, he will pull it up just as he would if he were awake, only
not quite so quickly. What do you suppose makes the muscles of the leg
contract when the brain is asleep and does not know that the foot is
being tickled? And here is another curious fact. When you were coming to
school this morning you did not have to think about every step you took.
Perhaps you were talking or looking over your lessons; but your legs
walked right along all the time, and without your thinking about them.
Can you tell how?

~22.~ It would be too much trouble for the large brain to stop to think
every time we step, and the little brain has work enough to do in taking
care of the heart and lungs and other organs, without keeping watch of
the feet when we are asleep, so as to pull them up if some mischievous
person tickles them. So Nature puts a few nerve cells in the spinal cord
which can do a certain easy kind of thinking. When we do things over and
over a great many times, these cells, after a time, learn to do them
without the help of the large brain. This is the way a piano-player
becomes so expert. He does not have to think all the time where each
finger is to go. After the tunes have been played a great many times,
the spinal cord knows them so well that it makes the hands play them
almost without any effort of the large brain.


SUMMARY.

1. The part of the body with which we think is the brain.

2. The brain is found filling the hollow place in the skull.

3. There are two brains, the large brain and the small brain.

4. Each brain is divided into two equal and complete halves, thus making
two pairs of brains.

5. The brain is largely made up of very small objects called nerve or
brain cells.

6. The nerve cells send out very fine branches which form the nerves.

7. The nerve branches or fibres run to every part of the body. They pass
out from the brain to the rest of the body through a number of openings
in the skull.

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

9. The spinal cord runs down through a canal in the backbone, and all
along gives off branches to the various parts of the body.

10. It gives us pain to prick or hurt the flesh in any way, because when
we do so we injure some of the little nerve branches of the brain cells.

11. When we suffer, we really feel a pain in the brain. We know this
because if a nerve is cut in two, we may hurt the part to which it goes
without giving any pain.

12. We have different kinds of nerves of feeling.

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

14. The nerves of work have charge of the heart, the lungs, the muscles,
the liver, the stomach, and every part of the body which can work or
act.

15. The brain and nerves control the body and make all the different
parts work together in harmony, just as a general controls an army.

16. The brain uses the nerves very much as a man uses the telephone or
telegraph wires.

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

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

19. The spinal cord does a still more simple kind of work. It enables us
to walk and to do other familiar acts without using the large brain to
think every moment just what we are doing.




CHAPTER XXIII.

HOW TO KEEP THE BRAIN AND NERVES HEALTHY.


~1. Uses of the Brain.~--What do you think a boy or girl would be good
for without any brain or nerves? Such a boy or girl could not see, hear,
feel, talk, run about, or play, and would not know any more than a
cabbage or a potato knows. If the brain or nerves are sick, they cannot
work well, and so are not worth as much as when they are healthy.

~2. The Brain Sympathizes with Other Organs.~--Did you ever have a
headache? Did you feel happy and good-natured when your head ached hard,
and could you study and play as well as when you are well? It is very
important that we should keep our brain and nerves healthy, and to do
this we must take good care of the stomach and all other organs, because
the brain sympathizes with them when they are sick.

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

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

~5. We should Take Muscular Exercise.~--When you get tired of study, an
hour's play, or exercise of some sort, rests you and makes you feel
brighter, so that you can learn more easily. This is because exercise is
necessary to make the blood circulate well. It will then carry out the
worn-out particles and supply the brain and nerves with fresh, pure
blood. So the same exercise which makes our muscles strong makes our
brains healthier also.

~6. We should be Careful of our Diet.~--We ought to eat plenty of good,
simple food, such as milk, fruits, grains, and vegetables. It is not
well for children to eat freely of meat, as it is very stimulating and
likely to excite the brain and make the nerves irritable. Mustard,
pepper, and all hot sauces and spices have a tendency to injure the
brain and nerves.

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

~8. We Ought Not to Allow Ourselves to Become Angry.~--When a person
flies into a passion he does his brain and nerves great harm. It is
really dangerous to get angry. Persons have dropped dead instantly in a
fit of anger.

~9. We should Shun Bad Habits.~--Bad habits are very hard to give up,
and hence we should be careful to avoid them. When a child learns to
swear, or to use slang phrases, the brain after a while will make him
swear or use bad words before he thinks. In a similar manner other bad
habits are acquired.


SUMMARY.

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

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

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

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

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

6. The brain gets strength by exercise, just as the muscles do. Hence,
study is healthful, and makes the brain strong.

7. A good memory is very necessary, but we should not try to remember
everything.

8. It is very important that we learn how to observe things closely.

9. Exercise in the open air rests and clears the brain by helping the
blood to circulate.

10. Plenty of wholesome and simple food is necessary to keep the brain
and nerves in good health. Spices, condiments, and rich foods in general
are stimulating and harmful.

11. Plenty of sleep is needed to rest the brain and nerves.

12. It is dangerous as well as wicked to become very angry.

13. We should be careful to avoid forming bad habits of any sort, as
they are hard to break, and often adhere to one through life.




CHAPTER XXIV.

BAD EFFECTS OF ALCOHOL UPON THE BRAIN AND NERVES.


~1. Drunkenness.~--Did you ever see a man who was drunk? If you live in
a city it is very likely that you have. How did the drunken man behave?
Perhaps he was noisy and silly. Perhaps he was angry and tried to pick a
quarrel with some one.

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

~3. The Whiskey Flush.~--You can almost always tell when a man has been
drinking, even when he has not taken enough to make him drunk. You know
by his flushed face and red eyes. When a man's face blushes from the use
of alcohol, his whole body blushes at the same time. His muscles, his
lungs, and his liver blush; his brain and spinal cord blush also.

~4.~ When a man has taken just enough alcohol to make his face blush a
little, the extra amount of blood in the brain makes him think and talk
more lively, and he is very jolly and gay. This makes many people think
that alcohol does them good. But if we notice what a man says when he is
excited by alcohol, we shall find that his remarks are often silly and
reckless. He says very unwise and foolish things, for which he feels
sorry when he becomes sober.

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

~6.~ A small amount of alcohol does not make a man dead drunk, but it
poisons and paralyzes his brain and nerves just according to the
quantity he takes.

~7.~ If a person holds a little alcohol in his mouth for a few moments,
the tongue and cheeks feel numb. This is because the alcohol paralyzes
them so that they cannot feel or taste. When taken into the stomach it
has much the same kind of effect upon the nerves of the whole body.

~8. Alcohol a Deceiver.~--A hungry man takes a drink of whiskey and
benumbs the nerves of his stomach so that he does not feel hungry.
Alcohol puts to sleep the sentinels which Nature has set in the body to
warn us of danger. A man who is cold takes alcohol and feels warm,
though he is really colder. He lies down in his false comfort and
freezes to death. A tired man takes his glass of grog and feels rested
and strong, though he is really weaker than before. A poor man gets
drunk and feels so rich that he spends what little money he has. The
alcohol paralyzes his judgment and steals away his good sense. Thus
alcohol is always a deceiver.

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

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

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

~12. Effects of Alcohol upon the Mind and Character.~--When a man is
under the influence of alcohol is his character good or bad? Is a man
likely to be good, or to be bad, when he is drunk or excited by drink?
Most men behave badly when they are drunk, and after they have been
drunk a great many times they often behave badly all the time. A great
many of the men who are shut up in prisons would not have been sent
there if they had never learned to drink.

~13. A Legacy.~--Do you know what a legacy is? If your father should die
and leave to you a fine house or farm, or money in the bank, or books,
or horses, or any other kind of property to have for your own, it would
be a legacy. When a person gets anything in this way from a parent we
say that he inherits it.

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

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

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

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

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

~19.~ Wise physicians will tell you that one reason why tobacco is bad
for boys is that it hurts their brains so that they cannot learn well,
and do not become as useful and successful men as they might be.

~20.~ Students in the naval and military schools of this country are not
allowed to use tobacco on account of its bad effects upon the mind. In
France the use of tobacco is forbidden to all students in the public
schools.

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

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

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


SUMMARY.

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

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

3. There are several things we ought not to do. We should not read or
study too much. We should not allow ourselves to become excited or
angry. We should avoid learning bad habits.

4. Alcohol paralyzes the brain and nerves.

5. Alcohol deceives a person who takes it by making him feel strong when
he is weak; warm when he is cold; rich when he is poor; well when he is
sick.

6. Alcohol makes men wicked. Most men who commit crimes are men who use
liquor.

7. The effects of tobacco upon the brain and nerves are much the same as
those of alcohol. Tobacco is very injurious to the mind.

8. Tobacco-using often leads boys to drunkenness and other vices.

9. The use of opium and chloral produces even worse effects than the use
of alcohol or tobacco.




CHAPTER XXV.

HOW WE HEAR, SEE, SMELL, TASTE, AND FEEL.


~1. The Senses.~--We have five senses--_hearing_, _seeing_, _smelling_,
_tasting_, and _feeling_. These are called special senses because they
are very different from each other. They also differ from the general
sense of feeling by means of which we feel pain when any part is hurt.

~2. Organs of the Special Senses.~--Each of the special senses has a
special set of nerves and also special cells in the brain which have
charge of them. We say that we see with our eyes, hear with our ears,
feel with our fingers, etc.; but, really, we see, hear, taste, and smell
in the brain just as we feel in the brain. The eyes, ears, nose, and
other organs of the special senses are the instruments by means of which
the brain sees, hears, smells, etc.

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

~4. The Ear.~--The part of the ear which we can see is shaped somewhat
like a trumpet. The small opening near the middle of the ear leads into
a _canal_ or tube which extends into the head about an inch. At the
inner end there is a curious little chamber. This is called the _drum_
of the ear, because between it and the canal of the ear there is
stretched a thin membrane like the head of a drum. The ear-drum is also
called the _middle ear_.

[Illustration: THE EAR.]

~5. Bones of the Ear.~--Within the drum of the ear there are three
curious little bones which are joined together so as to make a complete
chain, reaching from the drum-head to the other side of the drum. The
last bone fits into a little hole which leads into another curious
chamber. This chamber, which is called the _inner ear_, is filled with
fluid, and in this fluid the nerve of hearing is spread out. A part of
the inner ear looks very much like a snail shell.

[Illustration: THE INSIDE OF THE EAR.]

~6. How we Hear.~--Scratch with a pin upon one end of a long wooden
pole. Have some one listen with the ear placed close against the other
end of the pole. He will tell you that he hears the scratching of the
pin very plainly. This is because the scratching jars the ear and
especially the drum-head, which vibrates just as the head of a drum does
when it is beaten with a drum-stick. When the drum-head vibrates it
moves the bones of the ear, and these carry the vibration to the nerves
of hearing in the inner chamber. We hear all sounds in the same way,
only most sounds come to the ear through the air.

The snail-shell of the inner part of the ear hears musical sounds. The
rest of the inner ear hears ordinary sounds or noises.

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

(1.) Never use a pin, toothpick, or any other sharp instrument to clean
out the ear. There is great danger that the drum-head will be torn, and
thus the hearing will be injured. Neither is it ever necessary to use an
ear-spoon to remove the wax. Working at the ear causes more wax to form.

(2.) Do not allow cold water to enter the ear or a cold wind to blow
directly into it.

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

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

(5.) Boxing or pulling the ears is likely to produce deafness, and ought
never to be done.

~8. The Eye.~--The eye is one of the most wonderful organs in the whole
body. It enables us to know what is going on at some distance from us,
and to enjoy many beautiful things which our sense of hearing and other
senses can tell us nothing about. It also enables us to read. Let us
learn how this wonderful organ is made.

~9. The Eyeball.~--Looking at the eye, we see first a round part which
rolls in different directions. This is the _eyeball_. We see only the
front side of the eyeball as it fits into a hollow in the skull. Being
thus in a safe place, it is not likely to get hurt.

[Illustration: THE EYE.]

The eyeball is mostly filled with a clear substance very much like
jelly. It is so clear that the light can shine through it just as easily
as it can shine through water.

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

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

~12.~ If you look a little sidewise at the eyeball, you will see that
the curtain has something in front of it which is clear as glass. It is
about the shape of a watch crystal, only very much smaller. This is to
the eye what the glass is to the windows of a house. It closes the
opening in the front of the eyeball and yet lets the light shine in.

~13. The White of the Eye.~--The white of the eye is a tough, firm
membrane which encloses the eyeball and keeps it in a round shape.

~14. The Lens.~--Do you know what a lens is? Perhaps you do not know it
by this name, but you are familiar with the spectacles which people
sometimes wear to help their eyes. The glasses in the spectacle frames
are called lenses. Well, there is something in the eye almost exactly
like one of these lenses, only smaller. It is also called a _lens_. If
some one will get the eye of an ox for you, you can cut it open and find
this part. The lens is placed in the eyeball just behind the pupil. (See
picture.)

[Illustration: THE INSIDE OF THE EYE.]

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

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

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

~18. The Tear Gland.~--Do you know where the tears come from? There is a
little gland snugly placed away in the socket of the eye just above the
eyeball, which makes tears in the same way that the salivary glands make
saliva. It is called the _tear gland_. The gland usually makes just
enough tears to keep the eye moist. There are times when it makes more
than enough, as when something gets into the eye, or when we suffer pain
or feel unhappy. Then the tears are carried off by means of a little
tube which runs down into the nose from the inner corner of the eye.
When the tears are formed so fast that they cannot all get away through
this tube, they pass over the edge of the lower eyelid and flow down the
cheek.

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

~20. How we See.~--Now we want to know how we see with the eye. This is
not very easy to understand, but we can learn something about it. Let us
make a little experiment. Here is a glass lens. If we hold it before a
window and place a piece of smooth white paper behind it, we can see a
picture of the houses and trees and fences, and other things
out-of-doors. The picture made by the lens looks exactly like the view
out-of-doors, except that it is upside down. This is one of the curious
things that a lens does. The lens of the eye acts just like a glass
lens. It makes a picture of everything we see, upon the ends of the
nerves of sight which are spread out at the back of the eyeball. The
nerves of sight tell their nerves in the brain about the picture, just
as the nerves of feeling tell their cells when they are touched with a
pin; and this is how we see.

~21.~ Did you ever look through a spyglass or an opera-glass? If so, you
know you must make the tube longer or shorter according as you look at
things near by or far away. The eye also has to be changed a little
when we look from near to distant objects. Look out of the window at a
tree a long way off. Now place a lead pencil between the eyes and the
tree. You can scarcely see the pencil while you look sharply at the
tree, and if you look at the pencil you cannot see the tree distinctly.

~22.~ There is a little muscle in the eye which makes the change needed
to enable us to see objects close by as well as those which are farther
away. When people grow old the little muscles cannot do this so well,
and hence old people have to put on glasses to see objects near by, as
in reading. Children should not try to wear old persons' glasses, as
this is likely to injure their eyes.

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

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

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

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

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

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

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

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

[Illustration: INSIDE OF THE NOSE.]

~25.~ Smelling is a sort of feeling. The nerves of smell are so
sensitive that they can discover things in the air which we cannot taste
or see. An Indian uses his sense of smell to tell him whether things
are good to eat or not. He knows that things which have a pleasant smell
are likely to be good for him and not likely to make him sick.

We do not make so much use of the sense of smell as do the savages and
many lower animals, and hence we are not able to smell so acutely. Many
persons lose the sense of smell altogether, from neglecting colds in the
head.

~26. How we Taste.~--The tongue and the palate have very delicate nerves
by means of which we taste. We cannot taste with the whole of the
tongue. The very tip of the tongue has only nerves of touch or feeling.

~27.~ The use of the sense of taste is to give us pleasure and to tell
us whether different substances are healthful or injurious. Things which
are poisonous and likely to make us sick almost always have an
unpleasant taste as well as an unpleasant odor. Things which have a
pleasant taste are usually harmless.

~28. Bad Tastes.~--People sometimes learn to like things which have a
very unpleasant taste. Pepper, mustard, pepper-sauce, and other hot
sauces, alcohol, and tobacco are harmful substances of this sort. When
used freely they injure the sense of taste so that it cannot detect and
enjoy fine and delicate flavors. These substances, as we have elsewhere
learned, also do the stomach harm and injure the nerves and other parts
of the body.

~29. The Sense of Touch.~--If you put your hand upon an object you can
tell whether it is hard or soft, smooth or rough, and can learn whether
it is round or square, or of some other shape. You are able to do this
by means of the nerves of touch, which are found in the skin in all
parts of the body. If you wished to know how an object feels, would you
touch it with the elbow, or the knee, or the cheek? You will say, No.
You would feel of it with the hand, and would touch it with the ends of
the fingers. You can feel objects better with the ends of the fingers
because there are more nerves of touch in the part of the skin covering
the ends of the fingers than in most other parts of the body.

~30.~ The sense of touch is more delicate in the tip of the tongue than
in any other part. This is because it is necessary to use the sense of
touch in the tongue to assist the sense of taste in finding out whether
things are good to eat or not. The sense of touch is also very useful to
us in many other ways. We hardly know how useful it really is until we
are deprived of some of our other senses, as sight or hearing. In a
blind man the sense of touch often becomes surprisingly acute.

~31. Effects of Alcohol and Tobacco on the Special Senses.~--All the
special senses--hearing, seeing, smelling, tasting, feeling--depend upon
the brain and nerves. Whatever does harm to the brain and nerves must
injure the special senses also. We have learned how alcohol and tobacco,
and all other narcotics and stimulants, injure and sometimes destroy the
brain cells and their nerve branches, and so we can understand that a
person who uses these poisonous substances will, by so doing, injure the
delicate organs with which he hears, sees, smells, etc.

~32.~ Persons who use tobacco and strong drink sometimes become blind,
because these poisons injure the nerves of sight. The ears are
frequently injured by the use of tobacco. Smoking cigarettes and
snuff-taking destroy the sense of smell. The poison of the tobacco
paralyzes the nerves of taste so that they cannot detect flavors.
Tea-tasters and other persons who need to have a delicate sense of taste
do not use either alcohol or tobacco.


SUMMARY.

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

2. The ear is the organ of hearing, and has three parts, called the
external ear, the middle ear, and the inner ear. The inner ear contains
the nerve of hearing.

3. The middle ear is separated from the external ear by the drum-head.
The drum-head is connected with the inner ear by a chain of bones.

4. Sounds cause the drum-head to vibrate. The ear-bones convey the
vibration from the drum-head to the nerve of hearing.

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

6. The eye is the organ of sight. The chief parts of the eye are the
eyeball, the socket, and the eyelids.

7. In the eyeball are the pupil, the lens, and the nerve of sight.

8. The eyeball is moved in various directions by six small muscles.

9. The eye is moistened by tears from the tear-gland.

10. When we look at an object the lens of the eye makes a picture on the
nerve of sight, at the back part of the eyeball.

11. To keep the eyes healthy we should be careful not to tax them long
at a time with fine work, or to use them in a poor light.

12. The nerves of smell are placed in the upper part of the inside of
the nose.

13. "Colds" often destroy the sense of smell.

14. The nerves of taste are placed in the tongue and palate.

15. Many things which we think we taste we really do not taste, but
smell or feel.

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

17. Pepper, mustard, etc., as well as alcohol and tobacco, have an
unpleasant taste, and are not healthful. If we use them we shall injure
the nerves of taste as well as other parts of the body.

18. We feel objects by means of the sense of touch.

19. The sense of touch is most acute at the tip of the tongue and the
ends of the fingers.




CHAPTER XXVI.

ALCOHOL.


~1.~ As we learned in the early part of our study of this subject,
alcohol is produced by _fermentation_. It is afterwards separated from
water and other substances by _distillation_. We will now learn a few
more things about alcohol.

~2. Alcohol Burns.~--If alcohol is placed in a lamp, it will burn much
like kerosene oil. Indeed, it does not need a lamp to help it burn as
does oil. If a few drops of alcohol are placed upon a plate, it may be
lighted with a match, and will burn with a pale blue flame. Thus you see
that alcohol is a sort of burning fluid.

~3.~ The vapor of alcohol will burn also, and under some circumstances
it will explode. On this account it is better not to try any experiments
with it unless some older person is close by to direct you, so that no
harm may be done. Alcohol is really a dangerous substance even though we
do not take it as a drink.

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

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

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

[Illustration: Alcohol experiment.]

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

~8.~ You may have heard that sometimes men take such quantities of
liquor that the breath becomes strong with the vapor of alcohol and
takes fire when a light is brought near the mouth. These stories are
probably not true, although it sometimes happens that persons become
diseased in such a way that the breath will take fire if it comes in
contact with a light. Alcohol may be a cause of this kind of disease.

~9. Making Alcohol.~--It may be that some of our young readers would
like to find out for themselves that alcohol is really made by
fermentation. This may be done by an easy experiment. You know that
yeast will cause bread to "rise" or ferment. As we have elsewhere
learned, a little alcohol is formed in the fermentation of bread, but is
driven off by the heat of the oven in baking, so that we do not take any
of it into our stomachs when we eat the bread. If we place a little
baker's yeast in sweetened water, it will cause it to ferment and
produce alcohol. To make alcohol, all we have to do is to place a little
yeast and some sweetened water in a bottle and put it away in a warm
place for a few hours until it has had time to ferment. You will know
when fermentation has taken place by the great number of small bubbles
which appear. When the liquid has fermented, you may prove that alcohol
is present by means of the same experiment by which you found the
alcohol in cider or wine. (See page 160.)

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

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

~12.~ The next thing the brewer does is to grind the sprouted grain and
soak it in water. The water dissolves out the sugar. Next he adds yeast
to the sweet liquor and allows it to ferment, thus converting the sugar
into alcohol. Potatoes are sometimes treated in a similar way.

~13.~ By distilling beer, a strong liquor known as whiskey is obtained.
Sometimes juniper berries are distilled with the beer. The liquor
obtained is then called gin. In the West Indies, on the great sugar
plantations, large quantities of liquor are made from the skimmings and
cleanings of the vessels in which the sweet juice of the sugar-cane is
boiled down. These refuse matters are mixed with water and fermented,
then distilled. This liquor is called rum.

~14.~ Now you have learned enough about alcohol to know that it is not
produced by plants in the same way that food is, but that it is the
result of a sort of decay. In making alcohol, good food is destroyed and
made into a substance which is not fit for food, and which produces a
great amount of sickness and destroys many lives. Do you not think it a
pity that such great quantities of good corn and other grains should be
wasted in this way when they might be employed for a useful purpose?

~15. The Alcohol Family.~--Scientists tell us that there are several
different kinds of alcohol. Naphtha is a strong-smelling liquid
sometimes used by painters to thin their paint and make it dry quickly.
It does not have the same odor as alcohol, but it looks and acts very
much like it. It will burn as alcohol does. It kills animals and plants.
It will make a person drunk if he takes a sufficient quantity of it.
Indeed, it is so like alcohol that it really is a kind of alcohol.

~16.~ There are also other kinds of alcohol. Fusel-oil, a deadly poison,
is an alcohol. A very small amount of this alcohol will make a person
very drunk. Fusel-oil is found in bad whiskey. (All whiskey is bad, but
some kinds are worse than others.) This is why such whiskey makes men so
furiously drunk. It also causes speedy death in those who use it
frequently. There are still other kinds of alcohol, some of which are
even worse than fusel-oil. So you see this is a very bad family.

~17.~ Like most other bad families, this alcohol family has many bad
relations. You have heard of carbolic acid, a powerful poison. This is
one of the relatives of the alcohol family. Creosote is another
poisonous substance closely related to alcohol. Ether and chloroform, by
which people are made insensible during surgical operations, are also
relatives of alcohol. They are, in fact, made from alcohol. These
substances, although really useful, are very poisonous and dangerous. Do
you not think it will be very wise and prudent for you to have nothing
to do with alcohol in any form, even wine, beer, or cider, since it
belongs to such a bad family and has so many bad relations?

~18.~ Some persons think that they will suffer no harm if they take only
wine or beer, or perhaps hard cider. This is a great mistake. A person
may get drunk on any of these drinks if a sufficient amount be taken.
Besides, boys who use wine, beer, or cider, rarely fail to become fond
of stronger liquors. A great many men who have died drunkards began with
cider. Cider begins to ferment within a day or two after it is made, and
becomes stronger in alcohol all the time for many months.

~19. "Bitters."~--There are other liquids not called "drinks" which
contain alcohol. "Bitters" usually contain more alcohol than is found in
ale or wine, and sometimes more than in the strongest whiskey. "Jamaica
ginger" is almost pure alcohol. Hence, it is often as harmful for a
person to use these medicines freely as to use alcoholic liquors in any
other form.

~20.~ Alcoholic liquors of all kinds are often adulterated. That is,
they contain other poisons besides alcohol. In consequence of this,
they may become even more harmful than when pure; but this does not make
it safe to use even pure liquor. Alcohol is itself more harmful than the
other drugs usually added in adulteration. It is important that you
should know this, for many people think they will not suffer much harm
from the use of alcohol if they are careful to obtain pure liquors.

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

~22.~ A man once made an experiment by mistake. He was carrying some
alcohol across a lawn. He accidentally spilled some upon the grass. The
next day he found the grass as dead and brown as though it had been
scorched by fire.

~23.~ Mr. Darwin, the great naturalist, once made a curious experiment.
He took a little plant with three healthy green leaves, and shut it up
under a glass jar where there was a tea-spoonful of alcohol. The
alcohol was in a dish by itself, so it did not touch the plant; but the
vapor of the alcohol mixed with the air in the jar so that the plant had
to breathe it. In less than half an hour he took the plant out. Its
leaves were faded and somewhat shrivelled. The next morning it appeared
to be dead. Do you suppose the odor of milk or meat, or of any good
food, would affect a plant like that? Animals shut up with alcohol die
in just the same way.

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

~25.~ A few years ago Mr. Darwin thought that he would see what effect
alcohol would have upon the digestion of a plant. So he put a
fly-catching plant in a jar with some alcohol for just five minutes. The
alcohol did not touch the plant, because the jar was only wet with the
alcohol on the inside. When he took the plant out, he found that it
could not catch flies, and that its digestion was spoiled so that it
could not even digest very tender bits of meat which were placed on its
leaves. The plant was drunk.

~26.~ Mr. Darwin tried a great many experiments with various poisons,
and found that the plants were affected in much the same way by ether
and chloroform, and also by nicotine, the poisonous oil of tobacco.
Sugar, milk, and other foods had no such effect. This does not look much
as though alcohol would help digestion; does it?

~27. Effects of Alcohol on Digestion.~--Dr. Roberts, a very eminent
English scientist, made many experiments, a few years ago, to ascertain
positively about the effect of alcohol upon digestion. He concluded that
alcohol, even in small doses, delays digestion. This is quite contrary
to the belief of very many people, who suppose that wine, cider, or
stronger liquors aid digestion. The use of alcohol in the form of beer
or other alcoholic drinks is often a cause of serious disease of the
stomach and other digestive organs.

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

~29.~ When a person takes alcohol, it is found that instead of being
made warmer by it, he is not so warm as before. He feels warmer, but if
his temperature be ascertained by means of a thermometer placed in his
mouth, it is found that he is really colder. The more alcohol a person
takes the colder he becomes. If alcohol were good food would we expect
this to be the case? It is probably true that the alcohol does make a
little heat, but at the same time it causes us to lose much more heat
than it makes. The outside of the body is not so warm as the inside.
This is because the warm blood in the blood-vessels of the skin is
cooled more rapidly than the blood in the interior of the body. The
effect of alcohol is to cause the blood-vessels of the outside of the
body to become much enlarged. This is why the face becomes flushed. A
larger amount of warm blood is brought from the inside of the body to
the outside, where it is cooled very rapidly; and thus the body loses
heat, instead of gaining it, under the influence of alcohol. This is not
true of any proper food substance.

~30. Alcohol in the Polar Regions.~--Experience teaches the same thing
as science respecting the effect of alcohol. Captain Ross, Dr. Kane,
Captain Parry, Captain Hall, Lieutenant Greely, and many other famous
explorers who have spent long months amid the ice and snow and intense
cold of the countries near the North Pole, all say that alcohol does not
warm a man when he is cold, and does not keep him from getting cold.
Indeed, alcohol is considered so dangerous in these cold regions that no
Arctic explorer at the present time could be induced to use it. The
Hudson Bay Company do not allow the men who work for them to use any
kind of alcoholic liquors. Alcohol is a great deceiver, is it not? It
makes a man think he is warmer, when he is really colder. Many men are
frozen to death while drunk.

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

~32. Sunstroke.~--Do you know what sunstroke is? If you do not, your
parents or teacher will tell yow that persons exposed to the heat of the
sun on a hot summer day are sometimes overcome by it. They become weak,
giddy, or insensible, and not infrequently die. Scores of people are
sometimes stricken down in a single day in some of our large cities. It
may occur to you that if alcohol cools the body, it would be a good
thing for a person to take to prevent or relieve an attack of sunstroke.
On the contrary, it is found that those who use alcoholic drinks are
much more liable to sunstroke than others. This is on account of the
poisonous effects of the alcohol upon the nerves. No doctor would think
of giving alcohol in any form to a man suffering with sunstroke.

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

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

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

~34.~ This is the effect of strong alcohol. The alcohol of alcoholic
drinks has water and other things mixed with it, so that it does not act
so quickly nor so severely as pure alcohol; but the effect is
essentially the same in character. It is partly in this way that the
brain, nerves, muscles, and other tissues of drinking men and women
become diseased.

Eminent physicians tell us that a large share of the unfortunate persons
who are shut up in insane asylums are brought there by alcohol. Is it
not a dreadful thing that one's mind should be thus ruined by a useless
and harmful practice?


SUMMARY.

1. Alcohol is produced by fermentation, and obtained by distillation. It
will burn like kerosene oil and other burning fluids.

2. The vapor of alcohol will burn and will sometimes explode.

3. Alcohol may be separated from beer and other fermented liquids by
boiling.

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

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

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

7. All the members of the alcohol family are poisons; all will burn, and
all will intoxicate. The alcohol family have several bad relations,
among which are carbolic acid, ether, and chloroform.

8. Cider, beer, and wine are harmful and dangerous as well as strong
liquors. "Bitters" often contain as much alcohol as the strongest
liquors, and sometimes more.

9. Alcoholic liquors are sometimes adulterated, but they usually contain
no poison worse than alcohol. Pure alcohol is scarcely less dangerous
than that which is adulterated.

10. Death sometimes occurs almost instantly from taking strong liquors.

11. Alcohol will kill grass and other plants, if poured upon them or
about their roots.

12. Mr. Darwin proved that the vapor of alcohol will kill plants; also
that plants become intoxicated by breathing the vapor of alcohol.

13. Alcohol, even in small quantities, hinders digestion.

14. Alcohol causes the body to lose heat so rapidly that it becomes
cooler instead of warmer.

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

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

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

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

19. The effect of alcohol upon the brain, nerves, and other tissues of
the body is much the same as upon the beefsteak and the egg.




QUESTIONS FOR REVIEW.


CHAPTER I. THE HOUSE WE LIVE IN.--What is the body like? Does
the body resemble anything else besides a house? How is it like a
machine? Name the different parts of the body. What is anatomy?
physiology? hygiene?

CHAPTER II. A GENERAL VIEW OF THE BODY.--What are the main
parts of the body? Name the different parts of the head; of the trunk;
of each arm; of each leg. What covers the body?

CHAPTER III. THE INSIDE OF THE BODY.--What is the name of the
framework of the body? What is the skull? How is the back-bone formed?
Name the two cavities of the trunk. What does the chest contain? the
abdomen?

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

CHAPTER V. UNHEALTHFUL FOODS.--Is the flesh of diseased animals
good for food? What can you say about unripe, stale, or mouldy foods?
What is adulteration of foods? What foods are most likely to be
adulterated? Are pepper, mustard, and other condiments proper foods?
What about tobacco? What is the effect of tobacco upon boys?

CHAPTER VI. OUR DRINKS.--What is the only thing that will
satisfy thirst? Why do we need water? How does water sometimes become
impure? What is the effect of using impure water? What are the
properties of good water? Are tea and coffee good drinks? How is alcohol
made? Give familiar examples of fermentation. How are pure alcohol and
strong liquors made? Is alcohol a food? Why do you think it is a poison?
Do you think moderate drinking is healthful?

CHAPTER VII. HOW WE DIGEST.--What is digestion? What is the
digestive tube? Name the different digestive organs. How many sets of
teeth has a person in his lifetime? How many teeth in each set? How many
pairs of salivary glands? What do they form? What is the gullet?
Describe the stomach. What is the gastric juice? How long is the
intestinal canal? What fluid is formed in the intestines? Where is the
liver found, and how large is it? What does the liver produce? What is
the gall-bladder, and what is its use? What does the liver do besides
producing bile? What and where is the pancreas? What does the pancreas
do? Where is the spleen? How many important organs of digestion are
there? How many digestive fluids?

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

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

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

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

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

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

CHAPTER XIV. HOW TO KEEP THE LUNGS HEALTHY.--What is the thing
most necessary to preserve life? Name some of the ways in which the
blood becomes impure. Why is bad-smelling air dangerous to health? What
are germs? Why are some diseases "catching"? Name some such diseases.
What should be done with a person who has a "catching" disease? What is
the effect of the breath upon the air? How much air is poisoned and made
unfit to breathe by each breath? How much air do we spoil every minute?
every hour? How much pure air does each person need every minute? every
hour? How do we get fresh air into our houses? Why are windows and doors
not good means of ventilating in cold weather? How should a room be
ventilated? How should we use the lungs in breathing? What about the
clothing in reference to the lungs? Why is it injurious to breathe
habitually through the mouth? What is the effect of alcohol upon the
lungs? What is the effect of tobacco-using upon the throat and nose?

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

CHAPTER XVI. HOW TO TAKE CARE OF THE SKIN.--What happened to
the little boy who was covered with gold leaf? Why did he die? What is
the effect of neglecting to keep the skin clean? What is the effect of
wearing too much clothing and living in rooms which are too warm? How
should the hair be cared for? the nails? What is the effect of alcohol,
tobacco, and other narcotics upon the skin?

CHAPTER XVII. THE KIDNEYS AND THEIR WORK.--What is the work of
the kidneys? How may we keep these organs healthy? What is the effect of
alcohol upon the kidneys?

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

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

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

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

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

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

CHAPTER XXIV. BAD EFFECTS OF ALCOHOL UPON THE BRAIN AND
NERVES.--What is the effect of alcohol upon the brain and nerves?
Does alcohol produce real strength? Does it produce real warmth? Does
alcohol make people better or worse? What is the effect of tobacco upon
the brain and nerves? Does the use of tobacco lead to other evil habits?
What about the effect of opium and other narcotics?

CHAPTER XXV. HOW WE HEAR, SEE, SMELL, TASTE, AND FEEL.--How
many senses have we? What is the ear? Name the three parts of the ear.
How do we hear? How should we treat the ear?

Name the principal parts of the eye? What are found in the eyeball? How
is the eyeball moved in the socket? How is the eye moistened? Of what
use is the lens of the eye? Of what use is the pupil of the eye? How may
we preserve the eyesight?

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

Where are the nerves of taste found? How is the sense of taste sometimes
injured or lost? What do we detect with the sense of taste? Of what use
to us is the sense of taste?

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

CHAPTER XXVI. ALCOHOL.--How is alcohol produced? In what
respect is alcohol like kerosene oil? Is alcohol a dangerous thing even
if we do not drink it? How can you prove that there is alcohol in wine,
beer, cider, and other fermented drinks? Can you tell by the odor of his
breath when a person has been drinking? Why? Does the breath ever take
fire? May alcohol be a cause? From what is brandy made? How are whiskey,
gin, and rum made? Is alcohol a result of growth, like fruits and
grains, or of decay? Is there more than one kind of alcohol? Mention
some of the members of the alcohol family. In what ways are the members
of this family alike? Name some of the bad relations. Are cider and
beer, as well as whiskey, dangerous? Why? Mention some other things,
besides drinks, which contain alcohol. Are alcoholic drinks adulterated?
Is pure alcohol safe? Is instant death ever produced by alcohol? Will
alcohol kill plants? Describe Mr. Darwin's experiment which proved this.
Can plants be made drunk by alcohol? Describe the experiment which
proves this. What has Dr. Roberts proven concerning the influence of
alcohol upon digestion? How are our bodies kept warm? Explain how
alcohol makes the body cooler? Do Arctic explorers use alcohol? Why not?
Does the use of alcohol prevent sunstroke? What do Stanley and
Livingstone say about the use of alcohol in Africa? What is the effect
of using alcohol upon meat and eggs? What is the effect of alcohol upon
the brain and other tissues of the body? Does alcohol cause insanity and
other diseases of the brain and nerves?


FOOTNOTES:

[A] More properly _Carbonic dioxid_.

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


THE END.




Aids to Field and Laboratory Work in Botany

_Apgars' Plant Analysis._ By E.A. and A.C. APGAR.

Cloth, small 4to, 124 pages                                   55 cents

A book of blank schedules, adapted to Gray's Botanies, for pupils' use
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An analytical arrangement of botanical terms is provided, in which the
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~Chemistry~

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