m

BIOLOGY

LIBRARY

6

LIFE AND HEALTH

A TEXT-BOOK ON PHYSIOLOGY FOX

HIGH SCHOOLS, ACADEMIES

AND NORMAL SCHOOLS

BY

ALBERT F. BLAISDELL, M.D.

i/

AUTHOR OF "CHILD'S BOOK OF HEALTH," "HOW TO KEEP WELL"
" OUR BODIES AND HOW WE LIVE," "PRACTICAL PHYSIOLOGY"

GINN & COMPANY

BOSTON • NEW YORK • CHICAGO . LONDON

6:

BIOLOGV
LIBRARY
G

BLAISDELL'S
SERIES OF PHYSIOLOGIES

By ALBERT F. BLA1SDELL. M.D.

CHILD'S BOOK OF HEALTH

REVISED EDITION. In easy lessons for primary
grades. List price, 30 cents.

HOW TO KEEP WELL

. • , « • ; REVISED EDITION. A text-book on health for
«•./ '; tjie lovver grades. List price, 45 cents.

OUR BODIES AND HOW WE LIVE

REVISED EDITION. An elementary text-book
on physiology and hygiene for use in schools. List
price, 65 cents.

LIFE AND HEALTH

A text-book on physiology and hygiene for high
schools, academies, and normal schools. List price,
90 cents.

PRACTICAL PHYSIOLOGY

A text-book for higher schools. List price, $1.10.

How TO TEACH PHYSIOLOGY

A handbook for teachers. List price, 10 cents.

GINN & COMPANY Publishers

ENTERED AT STATIONERS' HALL

COPYRIGHT, 1902, 1910, BY
ALBERT F. BLAISDELL

ALL RIGHTS RESERVED

A 3 10.7

PREFACE

THIS book is intended to serve as a text-book on physi-
ology for such high schools, academies, and normal schools
as provide two terms, and occasionally only one term, for
this branch of study. For such secondary schools a shorter
and simpler book than the author's Practical Physiology is
needed. To meet this want the present book has been
written.

The general plan of the author's larger book has been
followed and a certain amount of its material and many of
its expensive woodcuts have been utilized. The text has
been simplified throughout and a large amount of new and
instructive matter has been added.

In this book, as in all the other books of this series of
school physiologies, the text has been supplemented by a
large number of carefully graded and practical experiments.
For the most part they are simple and can be performed
with apparatus that is inexpensive and easily obtained.

The few facts which the young student is able to learn
in school about the anatomy and physiology of the human
body are of little value in themselves. Such facts, however,
become of supreme importance and practical worth when
they enable him to understand a few of the great laws of
health and to apply them intelligently to his daily living.
Hence the author has aimed to lay marked emphasis upon
such points as bear directly upon personal health.

iii

M 207

iv Preface

Special effort has been made to utilize in the text of the
several chapters the latest teachings of modern hygiene
regarding the nature and propagation of bacteria, the
prevention and restriction of disease, and the preservation
of health.

Sundry sections have been printed in smaller type.
These may be omitted if it is deemed necessary to shorten
the course in physiology.

This text-book complies fully with the laws of those
states which require the study of the nature and the effects
of alcohol, tobacco, and other narcotics upon the human
system.

The author would acknowledge his indebtedness to
Dr. Margaret B. Wilson of New York City for editorial
assistance in revising the manuscript and reading the
proof.

A. F. BLAISDELL

BOSTON, June, 1902

PUBLISHERS' NOTE

The author of this book has written an additional chapter
(Chapter XV) on The Cause and Prevention of Tuberculosis,
or Consumption. This has been done in accordance with the
advice and suggestion of those educators and physicians who
believe that pupils in our public schools should be taught the
simplest facts concerning the cause and prevention of this
dread disease.

May, 1910

CONTENTS

CHAPTER I PACE

INTRODUCTION i

CHAPTER II
THE FRAMEWORK OF THE BODY 21

CHAPTER III
THE MUSCLES 49

CHAPTER IV
PHYSICAL EXERCISE 66

CHAPTER V
FOOD AND DRINK 79

CHAPTER VI
THE DIGESTION OF FOOD 98

CHAPTER VII
THE BLOOD AND ITS CIRCULATION 136

CHAPTER VIII
RESPIRATION 161

CHAPTER IX
THE SKIN AND THE KIDNEYS 184

vi Contents

CHAPTER x

PAGE

THE NERVOUS SYSTEM . 206

CHAPTER XI
THE SPECIAL SENSES 237

CHAPTER XII
THE THROAT AND THE VOICE 276

CHAPTER XIII

THE PRESERVATION OF HEALTH 286

Bacteria, 286; The Prevention and Restriction of Disease, 295;
The Care of the Sick Room, 298.

CHAPTER XIV
FIRST AID TO THE INJURED 302

CHAPTER XV
THE CAUSE AND PREVENTION OF TUBERCULOSIS, OR CONSUMPTION 317

APPENDIX 333

GLOSSARY 337

INDEX 353

LIFE AND HEALTH

CHAPTER I .\ i ::"vl?J
INTRODUCTION

1. Physiology in Schools. As a branch of study in our
schools, physiology aims to make clear certain laws of
health. Through a proper knowledge of these laws, and
their practical application, we may hope to spend happier
and more useful, because healthier, lives.

Hence, of all our school studies, no other should appeal
to us with such peculiar force as does physiology, for it is
the study of ourselves.

2. Questions which suggest themselves to the Thoughtful.
Physiology appeals to us even from the first in a deeply
personal way. Every thoughtful young person who takes
up this study will now begin, even if he has never done so
before, to ask himself a hundred questions about " the house
in which we live."

Why is breathing so essential to our life, and why can-
not we stop breathing when we try ? Where within us,
and how, burns the mysterious fire whose subtle heat
warms us from the first breath of infancy till the last hour
of life ?

How is it that we can lift these curtains of our eyes
and behold all the wonders of the world around us, then
drop them, and though at noonday, be instantly in

2 Life and Health

darkness ? How does the minute structure of the ear
report to us with equal accuracy the thunder of the tem-
pest and the hum of the passing bee ?

How can it be that the few articles of our daily food —
milk, bread, meats, and the like — build up our complex
bodies, and by what strange magic are they transformed
into skin, teeth, bones, muscles, and blood?

These and hundreds of similar questions it is the province
£$ physiology to answer.

3. The Profound Lessons taught by Physiology. The
study of physiology is not only interesting and useful, but it
should teach us some profound lessons. Every intelligent
person should not only wish to acquire the knowledge how
best to protect and preserve his body, but should feel a cer-
tain respect for an organism so wonderful as his physical
frame. For our bodies are indeed not ourselves, but the
frames that contain us, — the ships in which we, the real
selves, are borne over the sea of life. He must be indeed
a poor navigator who is not ever anxious so to direct his
ship that it may escape the rocks of disease and premature
decay, and that the voyage of his life may be long, pleasant,
and successful.

Again, let us always keep in mind the thought that
in studying physiology we are tracing in our bodies the
myriad lines of marvelous skill and forethought as they
appear in the work of the Divine Builder. However
closely we study our bodily structure, we are, at best, but
imperfect observers of the handiwork of Him who made
us as we are.

4, Some Salient Facts concerning our Bodies. Even a very
meager knowledge of the structure and action of our bodies
reveals certain salient facts which must hold the atten-
tion of every thoughtful student. Thus, our bodies move

Introduction 3

themselves, either one part on another, or the whole body
from place to place. The motive power is not from the
outside world, but the energy of the movements exists in
our bodies themselves.

Again, our bodies are continually breathing, that is, they
take in oxygen from the surrounding air. They take in
certain substances known as food, similar to those com-
posing the body, which are capable through a process
called oxidation, or through other chemical changes, of
setting free a certain amount of energy.

Our bodies are continually making heat and giving it out
to surrounding objects, the production and the loss of
which are so adjusted that the whole body is warm, that is,
of a temperature which is higher as a whole than that of
surrounding objects.

Finally, our bodies are continually getting rid of so-called
waste-matters, the most important of which are products
of the oxidation of the material used as food, or of the
substances which make up the organism.

5. The Main Features that distinguish Living Bodies.
The living body, like the dead, is continually losing energy,
but unlike the dead body is .by means of food continu-
ally restoring its substance and replenishing its stock of
energy. A great deal of energy thus stored up in the
living body is utilized in doing mechanical work, that is, it is
used in performing the various movements of the body. On
the other hand, the energy set free in the dead body by
oxidation and other chemical changes leaves the body for
the most part in the form of heat. We shall learn later on
that much of the energy which at last leaves the body as
heat exists for a time within the living body in other forms
than heat, though eventually transformed into heat. The
dead body, left to itself, slowly decays, that is, it slowly

4 Life and Health

combines with oxygen, slowly gives out heat, and therefore
slowly loses its store of energy. Even a slight change in
the surroundings of living bodies may rapidly, profoundly,
and in special ways, affect not only the amount but the kind
of energy set free. Thus the mere touch of a hair on some
particular surface may lead to such a discharge of energy
that a. body previously at rest may be suddenly thrown
into violent convulsions. This is especially true in certain
diseases, for example, lockjaw.

The main problem we have to solve in the study of
physiology is to ascertain how it is that our living bodies
can renew their substance and replenish the energy which
they are continually losing, and can, according to the nature
of their surroundings, vary not only the amount but the
kind of energy which they set free.

Hence, in all our future work, we must keep steadily in
mind the two great fundamental divisions of physiology :

One which has to do with the renewal of substance and the
replenishment of energy ; the other which deals with the setting
free of energy.

6. Life is Incessant Change. All living structures are
subject to constant decay. Life is a condition of incessant
changes, dependent upon two opposite processes, repair and
decay. A considerable part of our bodies wastes every
day, and the part which is wasted must be replaced. Thus
our bodies are not composed of exactly the same particles
from day to day, or even from one moment to another,
although to all appearance we remain the same individuals.
For instance, we are never of the same weight for two
minutes together ; but the change is so gradual, and the
renewal of that which is lost may be so exact, that no
difference can be noticed except at somewhat long inter-
vals of time.

Introduction 5

7. The Metabolism of the Body. The process of build-
ing up the materials of the body from simpler materials is
called anabolism.

The breaking down of the materials of the body into
simpler substances is known as katabolism.

The entire series of changes that take place in the living
body, beginning with the building up of its materials and
ending with the casting out of wastes, is included in one
word, metabolism.

The reduction of complex to simple substances results
in the setting free of energy in the forms of heat and
mechanical motion. Thus a complex substance, like a
piece of muscle, or lean meat, is built up of many millions
of molecules, each composed of a number of atoms arranged
in a definite way. Force or energy was, of course, required
for this regular arrangement of the atoms.

Now when this material is reduced by the process of
oxidation to substances consisting of simpler molecules,
such as carbon dioxide, urea, and water, the force stored
up in the muscle as potential energy becomes manifest and is
used as kinetic energy, or active life force.

8. Technical Terms defined. All living organisms may
be studied from two points of view : first, as to their form
and structure ; second, as to the processes which go on
within them.

The science which treats of all living organisms is called
biology. It has naturally two divisions :

Morphology, which treats of the form and structure of
living beings.

Physiology, which investigates their functions, or the
special work done in their vital processes. The word
physiology is from two Greek words ((^ucrt? and ^0709) and
means literally a talk or discourse about nature.

6 Life and Hcalt/i

The word anatomy, however, is usually employed instead
of morphology. It is derived from two Greek words
(ava and refiva)) and literally means a cutting up or
dissecting.

Humanjmatomy deals with the form and structure of the
human body, and describes how the different parts are
arranged, as learned by observation of the body as a whole,
by dissection, and by the use of the microscope.

Histology, or " minute anatomy," is that part of biology
which treats of the minute structure of the tissues of the
body, as revealed by the microscope.

Human physiology describes the various processes that go
on in the human body in health. It treats of the work
done by the various parts of the body, and of the results
of the harmonious action of the several organs.

Broadly speaking, physiology is the science which treats
of the functions of living organized beings.

By the word function is meant the special work which an
organ has to do.

An organ is a part of the body which does a special
work. Thus the eye is an organ of sight, the stomach of
digestion, and the lungs of breathing.

The word hygiene^ is often used in this branch of study.
It treats of the health or physical welfare of the
individual and of the community. Thus we speak of
"personal hygiene," "public hygiene," "public health,"
and "sanitation."

We cannot understand the physiology of our bodies
without some knowledge of their anatomy. An engineer
could not understand the working of his engine unless he
was well acquainted with all its parts, and the manner in
which they were fitted together. So, if we are to under-
stand the principles of elementary physiology, we must

Introduction 7

master a few of the main anatomical facts concerning
the organs of the body before considering their special
functions.

NOTE. — A more accurate title for the subject-matter of this
branch of study as now treated in text-books for elementary schools
would be " Anatomy, Physiology, and Hygiene." By common usage,
however, the word " Physiology " is quite generally used as a more
condensed and convenient name.

CHEMICAL COMPOSITION OF THE BODY

9. Chemical Elements in the Body. All the various com-
plex substances found in nature can be reduced by chemi-
cal analysis to about 70 elements, which cannot be further
divided. By various combinations of these 70 elements
all the substances known to exist in the world of nature
are built up. When a human body is submitted to chemi-
cal analysis, it is found that the bones, muscles, teeth,
blood, etc., may be reduced to a few chemical elements.

In fact, the human body is almost entirely composed of
1 3 of the 70 elements, namely : oxygen, hydrogen, nitrogen,
chlorine, fluorine, carbon, phosphorus, sulphur, calcium, potassium,
sodium, magnesium, and iron. Besides these, a few of the
other elements, as silicon and iodine, have been found ; but
they exist in extremely minute quantities.

Oxygen, hydrogen, and nitrogen, which are gases in
their uncombined form, make up three-fourths of the weight
of the whole human body. Carbon, which exists in an
impure state in charcoal, forms more than one-fifth of the
weight of the body. Thus, carbon and the three gases
named make up about 96 per cent of the total weight of
the body.

V We must keep in mind that, with slight exceptions, none
of these elements exist in their elementary form in the

8 Life and Health

animal economy. They are combined in various propor-
tions, the compounds differing widely from the elements
of which they consist. Thus, oxygen and hydrogen unite
to form water, and water forms more than two-thirds of
the weight of the whole body.

• 10. Inorganic Salts. A large number of the elements
of the body unite one with another by chemical affinity and
form inorganic salts. Thus, sodium and chlorine unite and
form chloride of sodium, or common salt. This is found
in all the tissues and fluids, and is one of the most impor-
tant inorganic salts the body contains. It is absolutely
necessary for continued existence.

By a combination of phosphorus and oxygen with sodium,
potassium, calcium, or magnesium, the various phosphates
are formed. The phosphates of lime and soda are the most
abundant of the salts of the body. For instance, they form
more than half the material of the bones.

The special place of iron is in the coloring matter of the
blood. Its various salts are also found in small quantities
in the ash of bones, in muscles, and in many other tissues.

11. Organic Compounds. Besides the inorganic materials,
there exists in the human body a series of compound sub-
stances formed by the union of the elements just described,
which always require the agency of living structures for
their formation. They are built up from the elements or
from simple mineral compounds by plants, and are called
organic compounds. Human beings and the lower animals
take such of these organized materials as they require, and
build them up into the materials of their own bodies, often
forming still more highly organized forms in the process.

Whatever other elements they may contain the organic
compounds of the body are invariably composed chiefly of
carbon, hydrogen, and oxygen.

'Introduction 9

The principal organic compounds found in the body are
usually divided into three great classes :

1. Proteids, or albuminous substances.

2. Carbohydrates (starches, sugars, and gums).

3. Fats.

The extent to which these three great classes of organic
materials of the body exist in the animal and vegetable
kingdoms, and are utilized for the food of man, will be dis-
cussed in the chapter on food (Chapter V).

12. The Proteids. The proteids, because they contain the
element nitrogen while the others mentioned above do not,
are frequently called nitrogenous, and the other two are
known as non-nitrogenous substances.

The proteids, the type of which is egg albumin, or the
white of egg, are found in muscle and nerve, in glands, in
blood, and in nearly all the fluids of the body. A human
body is estimated to contain on an average about 18 per
cent of albuminous substances.

In succeeding chapters we shall have occasion to refer to
various proteids and substances allied to them as they exist
in muscle (myosin), coagulated blood (fibrin), and bones
(gelatin).

13. The Carbohydrates. The carbohydrates are formed of
carbon, hydrogen, and oxygen, the last two in the propor-
tion to form water. Thus, we have animal starch, or glyco-
gen, stored up in the liver. Sugar, as grape sugar, is also
found in the liver.

14. The Fats. The body of an average man contains
about 10 per cent of fats. These are formed of carbon,
hydrogen, and oxygen, in which the latter two are not in the
proportion to form water. The fat of the body consists of
a mixture which is liquid at the ordinary temperature.

io Life and Health

It must not be supposed that the various chemical elements,
as the proteids, the salts, the fats, etc., exist in the body in a
condition to be easily separated one from another. Thus, a
piece of muscle contains all the various organic compounds
just mentioned, but they are combined, and in different cases
the amounts vary. Again, fat may exist in the muscles even
though it is not visible to the naked eye, and a microscope
is required to show the minute fat droplets.

THE MINUTE STRUCTURE OF THE TISSUES

15. Protoplasm. The ultimate living substance of the
body is called protoplasm.1

This material basis of all living things, whether plants
or animals, is a mixture of various organic compounds, the
chief of which, in all cases, are proteids.

16. Cells. When we carry back the analysis of an
organized body as far as we can, we find every part of it
made up of masses of protoplasm of various sizes and

shapes. Such bodies are technically
named cells. The white blood cor-
puscle is a typical cell having a nu-
cleus and nucleoli. Every cell has the
power of appropriating nutrient mate-
rial, of dividing and subdividing so as
to form new masses like itself. When
not built into a tissue, it has the power

°f chanSing its shaPe and °f moving

from place to place, by means of the

A, nucleus; B, nucleolus: ... . •"•.'« 11 -,

c, protoplasm. (Highly delicate projections, technically called
magnified.) processes, which it puts forth.

1 The word " protoplasm " must not be misunderstood to mean a substance
of a definite chemical nature, or of an invariable morphological structure ;
it is applied to any part of a cell which shows the properties of life, and is
therefore only a convenient abbreviation for the phrase, " mass of living
matter."

Introduction

ii

Every perfect cell consists of a cell-body and a nucleus.

In brief, then, a cell is a nucleated mass of protoplasm endowed

with the attributes of life. In this sense the term " cell " is

FIG. 2. Amoeboid Movement of a Human White Blood Corpuscle.
(Showing various phases of movement.)

now used. Every tissue of the human body is formed
through the agency of protoplasmic cells.

17. The Differentiation of Cells. The simplest forms of
animal life are organisms consisting of only one cell. Thus,
the amoeba begins its life as a cell split off from its parent.
This divides in its turn, and each half is a complete
amoeba. Organisms a little higher

than the amoeba consist of many
cells. As we ascend in the animal
scale the cells adapt themselves to
perform certain definite functions
and a division of labor occurs.
Technically, the cells are said to
undergo differentiation.

Cells having similar shape and func-
tion are grouped to form tissues, and
tissues are grouped to form organs.

18. Cells and the Human Organism. If the human body
be studied in its first stage of development, it is found to
originate from a single nucleated cell. From this original
cell, by growth and development, the body, with all its vari-
ous tissues, is built up. Many fully formed organs, like the
liver, consist chiefly of cells. Sometimes cells are modified

FIG. 3. Nerve Cells from
the Gray Matter of the
Cerebellum.
(Magnified 260 diameters.)

12 Life and Health

to form fibers, such as those of tendon, muscle, and nerve.
Later on we shall see that the white blood corpuscles
exhibit all the characters of the amoeba (Fig. 2). Even
such dense structures as bone, cartilage, and the teeth
contain cells which have for their duty in life the formation
and repair of the hard substances of these tissues.

In short, cells may be regarded as the anatomical units
of animal tissues, by the combination of which the body is
built up.

In addition to the living cells, every tissue contains more
or less of a lifeless substance between the cells called inter-
cellular substance, which is produced at some time by
the cells.

19. Kinds of Cells. Cells vary greatly in size, some of
the smallest being only -g-gVo of an inch or less in diam-
eter. They also vary greatly in form, as may be seen in
Figs. 4 and 6.

The typical free cell is usually globular in form, other
shapes being the result of pressure or of similar modifying
influences. The globular as well as the large flat cells
are well shown under the microscope in a drop of saliva
scraped from the tongue.

Then there are the columnar cells, found in various parts
of the intestines and the respiratory passages. The latter
cells sometimes have on the free surface delicate prolonga-
tions called cilia. Under the microscope they present a
wavy appearance, like that of a field of grain when the
wind blows over it (Fig. 6). There are, besides, cells
known as spindle, stellate, and pavement cells, and others
having various names suggested by their shapes.

Cells are also described as to their contents. Thus, fat
cells and pigment cells are alluded to in succeeding
sections.

Introduction

Cells may be described also with reference to their func-
tions or location or the tissue in which they are found,
as blood cells or corpuscles (Figs. 2 and 67), nerve cells
(Fig. 3), and connective-tissue cells.

20. Vital Properties of Cells. Each cell has a life of its
own. It manifests its vital properties in that it is born,
grows, multiplies, decays, and at last dies. During its life
it assimilates food, works,
rests, and is capable of
spontaneous motion and
frequently of locomotion.
Some cells live a brief life
of 12 to 24 hours, as is
probably the case with
many of the cells lining
the alimentary canal;
others may live for years,
as do the cells of cartilage
and bone.

A most interesting

FIG. 4. Various Forms of Cells.

A, columnar cells found lining various parts
of the intestines (called columnar epithe-
lium) ; B, cells of a fusiform or spindle
shape found in the loose tissue under the
skin and in other parts (called connective-
tissite cells) ; C, cell having many processes
— such are found in some kinds of connec-
tive tissue ; D, primitive cells composed of
protoplasm with nucleus, and having no cell
wall. All are represented about 400 times
their real size.

power of the living cell

is motion, a beautiful form of which is found in ciliated
epithelium (sec. 23). Cells may move actively and pas-
sively. In the blood the corpuscles are swept along by
the current, but some of the white corpuscles are able to
make their way actively through the tissues, as if guided
by some sort of instinct. They protrude a portion of their
protoplasm in the direction in which they wish to move and
then draw the rest of the body towards this "pseudopodium,"
or false foot. The property of protoplasm which makes
this movement possible is known as contractility. It is
possessed in some degree by all protoplasm, but it is the
characteristic property of the cells and fibers of muscle.

Life and Health

THE PRINCIPAL TISSUES OF THE BODY

21. The Chief Tissues classified. The chief tissues which
form the organs of the body may be classified as follows :

I. Nervous Tissues.

II. Muscular Tissues.

III. Epithelial Tissues.

IV. Connective Tissues

1. White and Elastic, Fibrous.

2. Areolar or Cellular.

3. Adipose or Fat.

4. Adenoid or Retiform.

5. Cartilage.

6. Osseous or Bone.

The most important tissues, the nervous and muscular, —
the " master tissues," - — are those by which the active life of
the individual is carried on. These
will be described in later chapters.

The remaining chief tissues — epi-
thelial and connective — will now be
briefly explained.

The osseous tissue, or bone, will be
described in Chapter II.

THE EPITHELIAL TISSUES

22. Epithelium. Cells are associ-
ated and combined in many ways to
form tissues. The distinctive charac-
ter of every tissue depends on its
structure, its mode of union, and the
FIG. 5. Cross-Section of vital properties of its elements.

Squamous Epithelium Qne Q£ the simplest Qf the tissues

from the (Esophagus. . ,. . .

is called epithelium, or surface-limiting
tissue, and the cells are known as epithelial cells.

Introduction

23. Varieties of Epithelium. The various kinds of
epithelial tissues are usually classified as squamous, glandu-
lar, and columnar.

The squamous, or pavement epithelium consists of very thin
flattened scales which form the outer layer of the skin and
the linings of the mouth.1

The glandular epithelium
forms the essential parts of
glands such as the liver and
the glands of the skin.

The columnar epithelium
consists of pear-shaped or
elongated cells, found fre-
quently on the mucous mem-
brane of the stomach and
intestines, and on the lining
of the large air tubes. FIG. 6. Various Kinds of

The ciliated epithelium (a Epithelial Cells.

.' r ,, , x . A. columnar cells of intestine : B. poly-

variety of the columnar) is 'hedral cells of the conjunctiva; c>

ciliated conical cells of the trachea ;
Z>, ciliated cell of frog's mouth ; E,
inverted conical cell of trachea ; F,
squamous cell of the cavity of the
mouth, seen on its broad surface;
G, squamous cell, seen edgeways.

marked by the presence of

very fine hair-like processes

called cilia, which develop

from the free end of the cell

and exhibit a rapid whip-like

movement as long as the cell is alive. This motion is

always to and fro in the same direction, and serves to

carry away mucus and even foreign particles in contact

with the membrane on which the cells are placed.

This kind of epithelium is especially common in the air
passages, where it serves to keep a free passage for the
entrance and exit of air.

1 A variety of the smooth pavement epithelium, called endothelium, lines
the heart and blood vessels and is the characteristic tissue of serous
membranes, like the pleura and the peritoneum (sees. 167 and 213).

1 6 Life and Health

THE CONNECTIVE TISSUES

24. Connective Tissues. vThe connective tissues serve
to unite and bind together the different organs and tissues.
Made up of fibers and cells, they form a sort of flexible
framework of the body. They so pervade every portion
of it that if all the other tissues were removed, we should
still have a complete representation of the bodily shape in
every part.

X In brief, the connective tissues may be said to serve as
packing, binding, and supporting structures. This name
includes certain tissues which to all outward appearance
vary greatly, but which are properly grouped together.

All these tissues consist of a ground-substance or matrix,
cells, and fibers.

The ground-substance is best seen in hyaline cartilage,
where it has a glossy appearance. In bone it is infiltrated
with the salts which give to the osseous tissue its hardness
and make it seem so unlike other tissues.

Experiment i. To examine squamous epithelium. With an ivory
paper-knife gently scrape the back of the tongue or the inside of the
lips or cheek ; place a tiny portion of the substance thus obtained
upon a glass slide ; cover it with a thin cover-glass, and if necessary
add a drop of water. Examine with the microscope, and the irregu-
larly formed epithelial cells will be seen.

Experiment 2. To examine ciliated epithelium. Open a frog's
mouth, and with the back of a knife-blade gently scrape a little of
the membrane from the roof of the mouth. Transfer to a glass slide,
add a drop of salt solution, and place over it a cover-glass with a hair
underneath to prevent pressure upon the cells. Examine with a micro-
scope under a high power. The cilia move very rapidly when quite
fresh, and are therefore not easily seen.

Introduction

FIG. 7. White Fibrous Tissue.
(Highly magnified.)

The cells are called connective-tissue corpuscles, cartilage
cells, and bone corpuscles, according to the type of the

tissues in which they occur.
The fibrous connective
tissues are composed of a
matrix in which are imbedded
the cells and two kinds of
connective-tissue fibers, white
and yellow or elastic. As the
character of connective tis-
sue depends largely on the
arrangement of these fibers,
they are worthy of special mention.

25. Connective Tissue with White Fibers. The white
fibers of connective tissue consist of bundles of very deli-
cate fibrils bound together by a small amount of cement
substance into bundles varying in size. Between the
fibrils protoplasmic masses (connective-tissue corpuscles)
are found. These fibers may be so

interwoven as to form a sheet, as
in the periosteum of the bone, the
fasciae around muscles, and the cap-
sules of organs ; or they may be
aggregated into bundles and form
rope-like bands, as in the ligaments
of joints and the tendons of muscles.

26. Connective Tissue with Yellow
or Elastic Fibers. The yellow or
elastic fibers of connective tissue are

much stronger and coarser than those of the white. They
are yellowish, tend to coil up like a broken spring, and are
highly elastic. It is these fibers which give elasticity to
the skin and to the coats of the arteries. Their typical

FIG. 8. Yellow Elastic

Tissue.
(Highly magnified.)

i8

Life and Health

form occurs in the ligaments which bind the vertebrae
together, in the true vocal cords, and in certain ligaments
of the larynx.

27. Areolar or Cellular Tissue. This tissue, thus named
by the older anatomists, consists of bundles of delicate
fibers interlacing and crossing one another, forming irregular

spaces or meshes. These little
spaces, in health, are filled with
fluid that has oozed out of the
blood vessels. The areolar tissue
forms a protective covering for
delicate and important organs.
X 28. Adipose or Fatty Tissue.
In almost every part of the body
there is found a variable quan-
tity of adipose or fatty tissue.
Examined by the microscope,
the fat cells are seen to be
minute sacs of exceedingly
delicate, structureless membrane
filled with oil.

This tissue is usually plentiful
beneath the skin, in the abdom-
inal cavity, on the surface of the
heart, in the marrow of bones, and elsewhere.

Experiment 3. To examine white fibrous tissue. Snip off a very
minute portion from a tendon of a rabbit, or any small animal
recently dead. Tease the specimen with needles, mount in salt solu-
tion, and examine under a high power. Note the course and characters
of the fibers.

Experiment 4. To examine elastic tissue. Tease out a small
piece of ligament from a rabbit's leg in salt solution ; mount in the
same, and examine as before. Note the curled elastic fibers.

FIG. 9. Retiform Connective
Tissue from a Lymph Gland.

Introduction

29. Adenoid or Retiform Tissue. This is a variety of
connective tissue found in the tonsils, spleen, lymphatic
glands, and allied structures. It consists of a very fine
network of fibrils, around which are cells of various sizes.

30, Cartilage. Cartilage, or gristle, is
a tough but highly elastic tissue. Under
the microscope it is seen to consist of a
matrix, or base, in which nucleated cells
abound, either singly or in groups.

Cartilage has sometimes the appear-
ance of fine ground glass, when it is
spoken of as hyaline. This kind of car-
tilage forms the early state of most of
the bones, and is also a permanent
coating for the articular ends of long
bones.

In other cases the matrix is almost
replaced by white fibrous tissue. This
is called white fibro-cartilage, and is found
wtiere * great strength and a certain
amount of rigidity are required, as in the
disks between the bodies of the verte-

, . . r n , * . . , i, hyaline cartilage; 2.

brae, in the interior of the knee joint, in white fibro-cartiiage ;
the wrist and other joints, and also in the
lining of the grooves for various tendons.

Again, there is between the cells a meshwork of yellow
elastic fibers. This is called yellow or elastic fibro-cartilage,
and is found in the gristle of the external ear, in the
cartilage of the Eustachian tube, in the epiglottis and in
other parts of the larynx.

FIG. 10. Longitudi-
nal Section of Car-
• tilage.

3, white fibrous con-
nective tissue.

20 Life and Health

ADDITIONAL EXPERIMENTS

It may be well to postpone some of the experiments in histology
until kindred topics are met with in the succeeding chapters.

For general directions and explanations and also suggestions for
performing additional experiments, see the Appendix.

Experiment 5. To examine adipose tissue. Take a bit of fat
from the mesentery of a rabbit. Tease the specimen in salt solution
and mount in the same. Note the fat cells lying in a vascular
meshwork.

Experiment 6. To examine blood corpuscles. Wind a piece of
twine tightly around the last joint of a finger. Prick the skin with a
clean needle. A drop of blood will flow. Spread it out on a piece
of glass under a cover-glass and examine with the compound micro-
scope. A large number of red corpuscles may be seen and a few
colorless cells.

Experiment 7. To examine a typical nucleated cell. A colorless
human blood corpuscle is a typical nucleated cell. Dilute a drop of
fresh blood (to be obtained and examined as directed in the preced-
ing experiment) with water, or, still better, with very dilute acetic
acid. The spongy protoplasm of the colorless corpuscles swells1 up
and becomes, transparent. An internal rounded body becomes visible,
which is the nucleus.

When the blood under the microscope is stained with carmine fluid,
the nucleus is generally more deeply stained than the rest of the cor-
puscle. This may be done by placing a drop of carmine fluid on
the slide close to the edge of the cover-glass and pressing a piece of
blotting paper against the opposite edge of the cover-glass to absorb
a little of the liquid.

NOTE TO THE TEACHER. — The teacher is advised to use these
two most excellent handbooks : Peabody's Laboratory Exercises in
Anatomy and Physiology (H. Holt & Co.) ; Brown's Physiology for
the Laboratory (Ginn & Company).

Reference should also be made to the Outline of Requirements
in Anatomy, Physiology, and Hygiene for admission to Harvard
University.

CHAPTER II
THE FRAMEWORK OF THE BODY

31. The Bony Framework. The framework on which
the body is built consists chiefly of a large number of
bones, called the skeleton. There are in the adult human
body about two hundred distinct bones. The teeth are
not bones, but are a part of the structure of the skin.

The bones of the body give firmness, strength, and
protection to the soft tissues and vital organs. They
also form levers for the muscles to act upon, and thus
render possible many complicated movements.
* 32, Chemical Composition of Bone. Bone is composed
of earthy, or mineral matter (chiefly in the form of lime
salts), and of animal matter (principally gelatin), in the
proportion of two-thirds of the former to one-third of the
latter. The proportion of earthy to animal matter varies
with age. In infancy the bones are composed more largely
of animal matter and are more easily deformed than in
later life. Hence an infant's bones are not easily broken.
In childhood the bones still contain a larger percentage of

The Study of the Skeleton in the Schoolroom. A human
skeleton is almost a necessity in the study of bones and their
action. To this intent, schools of a higher grade should be
provided either with a mounted skeleton or with the separate
bones. Oftentimes a loan of a complete skeleton or many of
the bones can be secured of some medical man in the vicinity.
In fact, there is no other way to study properly the structure
and use of the bones and joints than by the bones themselves.

22 Life and Health

animal matter than in more advanced life, and are there-
fore more liable to bend than to break ; while in old age
they contain a greater percentage of mineral matter, and
are more easily broken.

Experiment 8. To show the mineral matter in bone. Put a large
soup bone on a hot, clear fire, and let it remain there until it is at a
red heat. At first it becomes black from the libera-
tion of the carbon of its organic matter, but at last
it turns white. Let it cool. The animal matter has
been burnt out, leaving the mineral, or earthy part,
a white, brittle substance of exactly the same shape.

Experiment 9. To show the animal matter in
bone. Add one-fourth of a cupful of muriatic acid
to a quart of water, and place the mixture in a wide-
mouthed bottle or glass fruit jar. Scrape and clean
FIG. ii. a chicken's leg bone, part of a sheep's rib, or any

The Fibula tied other small slender bone. Soak the bone in the acid
into a Knot mixture for a few days, adding a little more acid
after the Min- frOm time to time as the effervescence seems to
eral Matter has have ceased The mineral matter is slowly dis-
been dissolved solved and th bo although retaining its original
by Acid. . ....

form, loses its rigidity and becomes pliable, and so

soft as to be readily cut. If the experiment be carefully performed,
a long, thin bone may even be tied into a knot.

33. Physical Properties of Bone. A bone is not the
same in its structure in all parts. If we take a leg bone
of a sheep, or a large end of beef shin bone, and saw it
lengthwise in halves, we see two distinct structures. There
is a compact tissue which seems hard and solid as stone
forming the outside shell, and a honeycombed lighter
tissue inside having the appearance of a beautiful trellis-
work of thin bony plates. This spongy, or cancellous tissue
occurs in the interior of bones, and chiefly at the joint
ends. Not only is the cancellous tissue strong and light,
but it has another advantage, — that of breaking shocks.

The Framework of the Body 23

It will also be seen that the shaft is a hollow cylinder,
formed of compact tissue, enclosing a cavity called the
medullary canal, which is rilled with a soft, fatty substance
called the marrow of the bone. The mar-
row is richly supplied with blood vessels,
which enter the cavity through small open-
ings in the compact tissue. In fact, all
over the surface of bone are the openings
of minute canals leading into the substance.
One of these, especially constant and large
in many bones, is called the nutrient fora-
men, and transmits a special artery to
nourish the bone.

Experiment 10. Obtain a part of a beef shin
bone, or a portion of a sheep's or a calf's leg,
including if convenient the knee joint. Have the
bone sawed in two lengthwise, keeping the marrow
in place. Boil, scrape, and carefully clean one-half.
Note the compact and spongy parts, shaft, etc.

Experiment n. Trim off the flesh from the
second half. Note the pinkish-white appearance
of the bone, the marrow, and the tiny specks of
blood, etc. Knead a small piece of the marrow
in the palm ; note the oily appearance. Convert
some marrow into a liquid by heating. Contrast
this fresh bone with an old dry one. pIG I2 The Right

NOTE.- While waiting for class use, fresh bones Femur sawed in
should be kept in a cool place, carefully wrapped

in a cloth moistened with listerine, dilute carbolic (Showinif arranSe;

ment of compact
acid solution, or even glycerine solution — an ounce and cancenous tis-

to one pint of water. sue.)

34. The Periosteum. A fresh or living bone is invested
with a delicate membrane called the periosteum. It adheres
very closely to the bone, and covers every part except at

Life and Health

FIG. 13. The Skeleton.

The Framework of the Body

the joints and where it is protected
with cartilage. The periosteum is
richly supplied with blood vessels, and
plays an important part in the growth,
formation, and repair of the outside
of bone. If, therefore, the periosteum
be detached from the surface of the
bone by injury or disease, there is a
risk that a layer of the subjacent
bone will gradually lose its vitality
and soon die.1

35, Microscopic Structure of Bone.
If a very thin slice of bone be cut
from the compact tissue and examined
under a microscope, numerous minute
openings are seen.2 Around these are
arranged rings of bone, with little
black bodies .in them, from which
radiate fine dark lines. These open-
ings are sections of canals called
Haversian canals, — after Havers, an
English physician, who first discovered

1 The periosteum is often of great practical
importance to the surgeon. Instances are on
record where bones have been removed, leaving
the periosteum, within which the entire bone
has grown again. Some years ago Dr. James
R. Wood, a famous surgeon in New York,
removed the whole lower jawbone from a young
woman, leaving the periosteum and even retain-
ing in position the teeth by a special apparatus.
The entire jawbone grew again, and the teeth
resumed their original places as it grew.

2 Mounted sections of bone and slides for the
study of other elementary tissues may be readily
procured of dealers in microscopical supplies'.

FIG. 14. Cross-Section
from Shaft of a Long
Bone.

(Little openings (Haversian
canals) are seen, and
around them are arranged
rings of bone with little
dark spaces, lacuna,
from which branch out
fine dark lines, canali-
culi.)

26

Life and Health

them. They are tunnels left in the compact substance of
the bone, through which run blood vessels for its nutri-
tion. The black bodies are minute cavities called lacuna,
while the fine lines are very minute canals, canaliculi,
which connect the lacunae and the Haversian canals.

The Haversian canals contain tiny blood vessels, while
the lacunae contain bone cells which have made the hard
material of the bone and are ready to make
more of it if occasion should arise. Very
fine branches from these bone cells pass
into the canaliculi in growing bone. The
canaliculi are far too small to allow the en-
trance of blood cells. They admit the
passage of nothing but a thin liquid from
the blood, the "plasma," which nourishes
the bone and -keeps it in a state fit for self-
repair when injured by disease or violence.
FIG. 15. Longitu- /36. The Self-Formative Power of Bones,
dinai Section of Thus bones are not d lifeless substances,

Bone.

(The Haversian canals but are the very type of activity and change,
are seen branching jn ijfe ^ey are not only richly supplied with

and communicat- . . . . . . , r

ing with one an- blood from the nutrient artery and from
other.) the periosteum covering the surfaces, but

they also contain countless little cells of
living material which maintain an endless network through-
out their whole structure.

Bones have, therefore, like all other living structures,
a self-formative power, and draw from the blood the mate-
rials for their own nutrition.

In all respects bones are as much cared for as are the
softer tissues of the body,

The Framework of the Body 2 7

THE BONES OF THE HEAD

^37. The Head, or Skull. The bones of the skeleton
may be divided for convenience into those of the head, the
trunk, and the limbs.

The bones of the head are described in two parts, — those
of the cranium, or brain-case, and those of the face. Taken
together, they form the skull.

38. The Cranium. The cranium is a dome-like structure,
made up in the adult of eight distinct bones firmly locked
together. These bones are :

1 Frontal, i Occipital,

2 Parietal, i Sphenoid,
•2 Temporal, i Ethmoid.

The frontal bone forms the forehead and front of the
head.

The parietal bones form the sides and roof of the skull.
The two bones make a beautiful arch to aid in the protection
of the brain.

The temporal bones form the temples on either side. In
each bone is the cavity containing three little bones which
form a part of the organs of hearing.

The occipital bone forms the lower part, or base, of the
skull, as well as the back of the head. Its lower part is
pierced by a large oval opening called the foramen magnum,
through which the spinal cord becomes continuous with
the brain.

The sphenoid bone is so called because it is wedged in
at the base of the skull between all the other bones of the
cranium, and locks together fourteen different bones. It
bears a fancied resemblance to a bat with extended wings
and forms a series of girders to the arches of the cranium.

28

Life and Health

The ethmoid bone is situated at the root of the nose and
forms a part of the floor of the cranium. It is a remark-
ably light and spongy bone, and is so called because it is
perforated with numerous holes like a sieve, through which
the nerves of smell pass from the nose to the brain.

FIG. 1 6. The Skull.

39. The Face. The face is made up of fourteen bones,
which, with the exception of the lower jaw, are, like those
of the cranium, closely interlocked with one another. By
this union these bones help form a number of cavities
which contain most important organs.

The Framework of the Body

29

The bones of the face serve, to a marked extent, to give
form to the human countenance. Upon these bones depend
the build of the forehead, the shape of the chin, the size
of the eyes, the prominence of the cheeks, the contour of
the nose, and other peculiarities which are reflected in the
beauty or ugliness of the face.

40. Bones of the Face. The bones of the face are :

2 Superior Maxillary,

2 Malar,

2 Nasal,

2 Lachrymal,

2 Palate,

2 Turbinated,

i Vomer,

i Lower Maxillary.

The superior maxillary or upper jawbones form a part of
the roof of the mouth and most of the floor of the orbits.
In them is fixed the upper set
of teeth.

The malar or cheek bones
are joined to the upper jaw-
bones, and help form the
sockets of the eyes.

The nasal or nose bones
are two very small bones be-
tween the eye sockets, which
form the bridge of the nose.

In the inner angles of the
orbit are the two small lachry-
mal bones.

The palate bones are behind
those of the upper jaw and
with them form the bony part
of the roof of the mouth.

The inferior turbinated are
spongy, scroll-like bones,

FIG. 17. The Base of the Skull.

A, palate process of upper jawbone ;

B, zygoma, forming zygomatic arch ;

C, condyle, for forming articulation
with atlas; D, foramen magnum;
E, occipital bone.

30 Life and Health

which curve about within the nasal cavities so as to increase
the surface of the air .passages of the nose.

The vomer serves as a thin and delicate partition between
the two cavities of the nose. It is so named from its resem-
blance to a ploughshare.

The largest bone in the face is the inferior maxillary,
or lower jaw. It has a horseshoe shape and supports the
lower set of teeth.

41. Sutures of the Skull. The edges of the bones of the
outer shell of the skull are joined together in a peculiar and
admirable manner. In adult life these edges, which are not
unlike the teeth of a saw in appearance, fit into each other
and grow together, suggesting the dovetailed joints used by
the cabinet-maker. When united these serrated edges look
almost as if sewed together ; hence their name, sutures. This
manner of union gives elasticity and strength to the skull.

In infants the corners of the parietal bones do not yet
meet, and the pulsations of the brain may be seen and felt
under these "soft spots," or fontanelles ("little fountains") as
they are called. Hence a slight blow to an infant's head may
cause serious injury to the brain. As old age creeps on, the
cap of the skull becomes a solid dome of bone, with alj trace
of the sutures lost.

42. The Hyoid Bone. Under the lower jaw is a little
horseshoe-shaped bone, called the hyoid bone, because it is
shaped like the Greek letter upsilon (Y). It really belongs
to the skull, although it lies in the neck. The root of the
tongue is fastened to the bend of the hyoid, and the larynx
is hung from it as from a hook. This bone serves to keep
open the top of the larynx, and to it are attached the muscles
which move the tongue.

Experiment 12. To locate the hyoid bone. Allow the neck to
rest in its natural position. Gently grasp with the thumb and fore-
finger the front of the throat, just above the " Adam's Apple." The
hyoid bone can be plainly felt 6n a level with the lower jaw and about
one inch and a half behind it.

The Framework of the Body 3 1

THE BONES OF THE TRUNK

* 43. The Bones of the Trunk. The bones of the trunk
may be subdivided into those of the spinal column, the ribs,
the sternum, and the hips.

The trunk includes fifty-three bones usually thus
arranged :

f 7 Cervical Vertebrae.

12 Dorsal Vertebrae.

I. Spinal Column, 26 bones : •{ 5 Lumbar Vertebrae.

i Sacrum.
i Coccyx.

II. Ribs, 24 bones: j '4 I™ ™*
[ 10 False Ribs.

III. Sternum. 9>-^*.
IV. Two Hip Bones.

> 44. The Spinal Column. The spinal column, or backbone,
is a most marvelous piece of mechanism. It is the central
structure, to which all the other parts of the skeleton are
adapted. It supports the head, encloses and protects the
spinal cord, and forms the basis for the attachment of
many important muscles, especially those which maintain
the body in an erect position.

The spinal column consists of numerous separate bones,
called vertebrae. The seven upper ones belong to the neck,
and are called cervical vertebrae. The next twelve are the
dorsal vertebrae ; these belong to the back and support the
ribs. The remaining five belong to the loins, and are
called lumbar vertebrae.

Each vertebra has an opening through its center, and
the separate bones so rest, one upon another, that these
openings form a continuous canal from the head, to the

Life and Health

lower part of the spine. The great
nervous organ, known as the spinal cord, <
together with some of the nerves which $
are attached to .it, extends from the (J
cranium through the entire length of
this canal.

Between the vertebrae are pads, or
cushions of cartilage. These act as
"buffers," and serve to give the spine
strength and elasticity and to prevent
friction of one bone on another. They
also serve to break the effect of shock
to the brain and the spinal cord from
any sudden jar or injury of the limbs or
the trunk.

45. The Sacrum and Coccyx. The
spinal column rests on a strong mass of
bone called the sacrum, or sacred-bone.
It is composed of five vertebrae
joined together, and is wedged in
between the hip bones, forming the
keystone of the pelvis. It is not
easy to say why this bone was called
"sacred." The reason generally
assigned is that it was used in
olden times in sacrifices.

Experiment 13. Run the tips of the
fingers briskly down the backbone, and
the spines of the vertebrae will be tipped
with red so that they can be readily
counted. Have the model lean forward
with the arms folded across the chest ;
this will make the spines of the vertebrae
more prominent.

COCCYX

FIG. 18.
The Spinal Column.

The Framework of the Body

33

Joined to the lower end of the sacrum is the coccyx, a
tapering series of little bones. It derives its. name from
a fancied resemblance to the beak of a cuckoo.

46. The Ribs. The barrel-shaped framework of the
chest is in part composed of long, slender, curved bones,
called ribs. There are twelve ribs on each side. Each
pair is attached to a dor-
sal vertebra behind.

The first seven pairs,
counting from the neck,
are called the true ribs,
and are joined by car-
tilages directly to the
breastbone. The five
lower pairs, called the
false ribs, are not directly
joined to the breastbone,
but are connected, with
the exception of the last
two, with each other and
with the last true ribs by
cartilages. These elastic
cartilages enable the
chest to bear great blows
with impunity. Thus a blow on the breastbone is distrib-
uted over fourteen elastic arches. The lowest two pairs
of false ribs are quite free in front, and for this reason are
often called " floating" ribs.

The ribs are not horizontal, but slope downwards from
the backbone, so that when raised or depressed by the strong
intercostal muscles, the size of the chest is alternately
increased or diminished. This movement of the ribs, as we
shall learn later, is of the utmost importance in breathing.

FIG. 19. Thorax.
(Anterior view.)

34 Life and Health

47. The Sternum, or Breastbone. In shape the sternum,
or breastbone, somewhat resembles an ancient dagger. It is
a long, flat, narrow bone, forming, the middle front wall of the
chest . It is connected directly with all the true ribs, indirectly
through cartilages with all the false ribs, except the " float-
ing" ribs. It also gives attachment to the collar bones.

48. The Pelvis. Four immovable bones are joined
together so as to form at the lower extremity of the
trunk a basin-like cavity called the pelvis. These four
bones are the sacrum and the coccyx, which have been
described, and the two hip bones.

49. The Hip Bones. The hip bones are large, irregularly
shaped bones, very firm and strong, and are often called
the haunch bones, or nameless bones (ossa innominatd).
They are united to the sacrum behind and joined to each
other in front. On the outer side of each hip bone is a
deep cup, or socket, into which fits the rounded head of
the thigh bone. It is called the acetabulum, because it
resembles an ancient vinegar cup.

THE BONES OF THE UPPER LIMBS

50. The Bones of the Upper Limbs. Each of the upper
limbs consists of the shoulder, arm, forearm, and hand.

The thirty-two bones of each upper limb are usually
classified as follows :

f Scapula, or shoulder-blade.
Shoulder: ^ Clavicle) or collar bone.

Ann : . . Humerus, or arm bone.
Forearm:

C 8 Carpal, or wrist bones.
Hand : . . J 5 Met a car pal bones.

I 14 Phalanges, or finger bone*.

The Framework of the Body

35

51. The Shoulder and Arm. The two

bones of the shoulder, the scapula and

the clavicle, serve to attach the arm to

the trunk.

The scapula, or shoulder-blade, is a

flat, triangular bone, lying on the upper
and back part of the
chest, over the ribs.
It consists of a broad,
flat portion and a
prominent ridge or
spine. At its outer
angle it has a shallow
cup known as the glen-
oid cavity, in which
plays the rounded head
of the humerus.

The clavicle, or collar
bone, so named from
its resemblance to an
ancient key, is a slen-
der bone with a double
curve like an italic /.
It extends horizontally
from the shoulder-

FIG' 2°r Left Clavicle, b,ade {o thg breast.
or Collar Joone.
(Anterior surface.) bone- I{ thuS

serves, like the

keystone of an arch, to hold the
shoulder-blade firmly in its place.
Its chief use is to keep the shoulders
wide apart, that the arm may enjoy
a free range of motion. This bone FIG. 21

Left Humerus.

Life and Health

FIG. 22.
Left Radius and Ulna.

is often broken by falls, or by blows upon
the shoulder or arm.

The humerus is the strongest
bone of the upper extremity.
Its rounded head rests on the
socket of the shoulder-blade,
forming a ball-and-socket joint,
which permits great freedom of
motion.

When the shoulder is dislo-
cated or " put out of joint," the
head of the humerus is forced
out of its socket. The lower
end of the bone is grooved to
help form a hinge joint at the
elbow with the bones of the
forearm.

52. The Forearm. The fore-
arm contains two long bones,
the ulna and the radius.

The ulna, so called because
it forms the elbow, is the longer
and larger bone of the fore-
arm, and is on the same side
as the little finger. It is con-
nected with the humerus by a
hinge joint at the elbow. It
is prevented from moving too
far back by a hook-like pro-
jection called the olecranon
process, which makes the
sharp point of the elbow.
The radius is the shorter of

The Framework of the Body

37

the two bones of the forearm, and is so called from its
resemblance to the spoke of a wheel. It is on the same
side as the thumb. Its slender upper end articulates
with the ulna and humerus ; its lower end is wider and
gives attachment in part to the bones of the wrist. This
bone radiates or .,

turns on the II:
ulna, carrying
the hand with it.

Experiment 14.
Rest the forearm
on a table, with
the palm up (an
attitude called
supination). The
radius is on the
outer side and par-
allel with the ulna.
If now, without
moving the elbow,
we turn the hand
(pronation) as if
to pick up some-
thing from the
table, the radius
may be seen and
felt crossing over
the ulna, while the
latter bone has
not moved.

FIG. 23. Bones of the Hand and Wrist, as shown

by an X-Ray Photograph.
(Two rings are plainly shown.)

/ 53. The Hand. The hand consists of twenty-seven sepa-
rate bones, and is divided into three parts, the wrist, the
palm, and the fingers^

The carpus, or wrist, consists of eight bones, arranged in
two rows of four each, and bound together with ligaments
which admit of ample flexibility. Thus the wrist is much

38 Life and Health

less liable to be broken than if it were to consist of a single
bone. The combined action of the carpal bones helps to
give the hand much freedom of action.

The metacarpal or palm bones are the five long bones of
the back of the hand.

The phalanges, or finger bones, are the fourteen small
bones arranged in three rows to form the fingers. Each
finger has three bones ; each thumb, two.
v 54. The Hand as a Marvel of Mechanism. The hand
has much strength and flexibility, and is thus enabled to
accomplish the countless movements so necessary to our
well-being. There, is no part of the body which cannot be
reached by the hand. It is a marvel of precise and adapted
mechanism, capable not only of performing every variety
of work and of expressing many emotions of the mind, but
of executing its orders with inconceivable rapidity.

THE BONES OF THE LOWER LIMBS

^ 55. The Bones of the Lower Limbs. The general struc-
ture and number of the bones of the lower limbs bear a
striking similarity to those of the upper limbs. Thus, the
leg, like the arm, is arranged in three parts, the thigh, the
leg, and the footer

The thirty bones of each lower limb are usually classified
as follows :

Thigh : Femur, or thigh bone.

f Tibia, or shin bone.
Leg : -\ Fibula, or splint bone.

[ Patella, or knee-cap.

f 7 Tarsal or ankle bones.
Foot : J 5 Metatarsal or instep bones.

I 14 Phalanges, or toe bones.

The Framework of the Body

56, The Femur, or Thigh Bone.

The longest and strongest of all the
bones is the femur, or thigh bone. Its
upper end has a rounded head which
fits into the acetabulum, or the deep
cup-like cavity of the hip bone, form-
ing a perfect ball-and-socket joint.
The rounded head fits so accurately
into its socket that it may be retained
by atmospheric pressure alone.

The shaft of the femur is strong,
and is ridged and roughened in places
for the attachment of the muscles.
Its lower end is broad and irregularly
shaped, having two prominences
called condyles, the whole fitted for
forming a hinge joint with the upper
end of the shin bone.
X 57. The Bones of the Leg. The
leg, like the forearm, consists of two
bones. The tibia, or shin bone, is
the long, three-sided bone forming
the front of the leg. The sharp
edge of the bone is easily felt just
under the skin. It articulates with
the lower end of the femur.

The fibula is a long, slender bone
on the outer side of the leg, and
is firmly fixed to the tibia at each
end. Its lower end forms the
outer projection of the ankle.

In front of the knee joint, im-
bedded in a thick, strong tendon,

39

FIG. 24. Right Femur, or
Thigh Bone.

40 Life and Health

is an irregularly disk-shaped bone,
the patella, or knee-cap. It in-
creases the leverage of important
muscles and protects the front of
the knee joint, which is, from its
position, much exposed to injury.

58. The Bones of the Foot. The
bones of the foot, twenty-six in num-
ber, consist of the tarsal bones, the
metatarsal, and the phalanges. The
tarsal bones are the seven small, irreg-
ular bones which make up the ankle.

The metatarsal bones, correspond-
ing to the metacarpals of the hand,
are five in number.

The phalanges are the fourteen
bones of the toes.

The bones of the foot are kept in
place by powerful ligaments, com-
bining great strength with elasticity.

NOTE. — It is wonderful what habit and
necessity will make the foot accomplish.
We who wear tight boots can hardly believe
it when we hear of persons carving, knitting,
writing, and even painting with the toes.

THE JOINTS

59. Formation of Joints. The

various bones of the skeleton are
connected at different parts of
their surfaces by joints, or articula-
tions, which vary according to the FIG. 25. Right Tibia and Fibula,
kind and the amount of motion. (Anterior surface.)

The Framework of the Body

The principal structures which
enter into the formation of a joint
are : bone, cartilage, synovial mem-
brane, and ligaments.

Bones make the chief element
of all the joints, and their -adjoin-
ing surfaces are shaped to meet
the special demands of each
joint. The joint-end of
bones is coated with a thin
layer of tough, elastic carti-
lage. This is also used at
the edge of joint-cavities,
forming a ring to deepen
them. The rounded heads
of bones which move in
them are thus more securely
held in their sockets.

Besides these structures,
the muscles al^o help to
maintain the joint-surfaces
in their proper relation.
Another essential to the
action of the joints is the
pressure of the outside
air. This may be suffi-
cient to keep the articular
surfaces in contact even
after all the muscles are
removed. Thus the hip
joint is so completely
surrounded by ligaments as
to be air-tight.

FIG. 26. Bones of Right Fooc.
(Dorsal surface.)

42 Life and Health

60. Synovial Membrane. A very delicate layer of cells
supported by connective tissue, called the synovial membrane,
lines the capsules of the joints and covers the ligaments
connected with them. It secretes the synovia, or joint oil,
a thick and glairy fluid, something like the white of a raw
egg in consistency, which moistens the inner surfaces of
the joints. Every part of a joint is thus enabled to run
with very little friction.

61. Ligaments. The bones are held in place, and their
movements limited to a certain extent, by bands of various
forms, called ligaments. These are composed mainly of
bundles of white fibrous tissue placed parallel to, or closely
interlaced with, one another, and present a shining, silvery
aspect.

While ligaments are pliable and flexible, permitting free
movement, they are also wonderfully strong, tough, and
inextensible. A bone may be broken, or its end torn off,
before its ligaments are ruptured.

62. Different Kinds of Joints. It is only perfect joints
that are fully equipped with the structures just men-
tioned. Some joints lack one or more, and are there-
fore called imperfect joints. Such joints allow little or no
motion.

The so-called perfect joints vary according to the nature
and amount of movement permitted. They are divided
into hinge joints, ball-and-socket joints, and pivot joints.

The hinge joints allow forward and backward movements
like a hinge. These joints are the most numerous in the
body, as at the elbow, the ankle, and the knee.

In the ball-and-socket joints — a beautiful contrivance —
the rounded head of one bone fits into a socket in the
other, as the hip joint and the shoulder joint. These
joints permit free motion in almost every direction.

The Framework of the Body

43

In the pivot joint a part of one bone fits into a notch in
another. The best example of this is the joint between
the first and second vertebrae. The radius moves around
on the ulna by means of a pivot joint.
v 63. Uses of the Bones. The bones serve many impor-
tant and useful purposes. The skeleton, a general frame-
work, affords protection, support, and
leverage to the other bodily tissues.
Thus, the bones of the skull and of
the chest protect the brain, the lungs,
and the heart. The long bones of
the limbs are levers to which muscles
are attached.

Bones have many different shapes.
Each bone is not only different from
all the others, but is also curiously
adapted to its particular place and
use.

We have seen how the bones of
the cranium are united by sutures,
the better to, allow the delicate brain
to grow, and to afford it protection
from violence.

The complicated organ of hearing
is protected by a winding series of
minute apartments in the rock-like
portion of the temporal bone. The socket for the eye Jias a
jutting ridge of bone around it to guard this organ against
injury. Grooves and canals, formed in hard bone, lodge
and protect minute nerves and tiny blood vessels. The
surfaces of bones are often provided with grooves, sharp
edges, and rough projections, for the origin and insertion
of muscles.

FIG. 27. Showing how
the Ends of the Bones
are shaped to form the
Elbow Joint.

(The cut ends of a few
ligaments are seen.)

44

Life and Health

* 64. How the Growth of Bones may be modified. Bones,
as we have seen, are the seat of active vital processes through-
out life, except perhaps in extreme old age. The final

knitting together of the ends of
some of the bones with their
shafts does not occur until some-
what late in life. For example,
the separate bones of the sacrum
do not fully knit into one solid
bone until the twenty-fifth year.
Hence the bones of young per-
sons should not be subjected to
the risk of undue violence from
injudicious physical exercise, as
in rowing, baseball, football, and
bicycle riding. Moderate exer-
cise, however, even in infancy,
promotes the health of the bones
as well as of the other tissues.

The bones are easily modified

in thdr SrOWth' TkuS the COn'

A, tendon of the semi-membranofTs tinued pressure of SOme morbid
muscle cut across; £, F, tendon deposit, as a tumor Or an en-
of same muscle ; C. internal con- , f

dyle of femur; A posterior crucial largement °f an artery, may
ligament; E, internal interarticu- cause the absorption Or distor-

FIG. 28. Section of the Knee

(Showing ernal structure.)

cap; A', fatty mass; Z,, anterior One of the Softer tisSUCS.
crucial Ugament; M, tendon of 65> Sprains. A twist Or Strain
thigh muscles ; P, patella.

of the ligaments and soft parts

about a joint is known as a sprain, and may result from
a great variety of accidents. When a person falls, the
foot is frequently caught under him, and the twist comes
upon the ligaments and other structures of the ankle.

The Framework of the Body 45

The ligaments cannot stretch, and so have to endure the
wrench upon the joint. The result is a sprained ankle.

Next to the ankle, a sprain of the wrist is most common.
A person tries, by throwing out his hand, to save himself
from a fall, and the weight of the body brings the strain
upon the firmly fixed wrist.

A sprain may be a slight affair, needing only a brief
rest, or it may be severe and painful enough to call for the
most skillful treatment by a surgeon. Lack of prompt
and proper care in treating sprains is often the cause of
a crippled ankle or knee.

66. Dislocations. A fall or a blow may bring such a
sudden wrench or twist upon the ligaments as to force
a bone out of place. This displacement is known as a
dislocation. It should be treated by a surgeon at once. Any
delay or carelessness may make a serious and painful affair
of it, as the torn and bruised parts rapidly swell and
become extremely sensitive.

67. Different Kinds of Fractures. The bones of the
body are often fractured or broken. The simple fracture
is the most common form, the bone being broken in a
single place with no opening through the skin. When
properly adjusted, the bone heals rapidly. When, besides
the broken bone, there is an opening through the soft parts
to the surface of the body, we have a compound fracture.
This is a serious injury and calls for prompt surgical
treatment.

68. How Bones are broken. Bones may be broken by
direct violence, as when they are fractured at a certain
point by some powerful force, as a blow from a baseball
bat or a fall from a horse. Again, bones may be broken
by indirect violence, as when a person, being about to fall,
throws out his hand to save himself. The force of the

46 Life and Health

fall on the hand often breaks the wrist, by which is meant
usually the fracture of the lower end of the radius. This
accident is common in winter from a fall or slip on the ice.

69, Treatment for Broken Bones. When a bone is
broken a surgeon is needed to set it ; that is, to bring the
broken parts into their natural position, and retain them
by proper appliances.

With old people a broken bone is often a serious matter,
and may cripple them for life, or prove fatal. A trifling
fall, for instance, may cause a "broken hip." From the
shock of such an injury, and the subsequent pain and
exhaustion, an aged person may die in a few weeks.

In young people, however, the parts of a broken bone
will knit together usually in three or four weeks after the
fracture is reduced ; while in adults six or even more may
be required for firm union.

After a broken bone is strong enough to be used, it is
fragile for some time, and great care must be taken,
especially with children, that the injured parts may not be
broken again before perfect union takes place.

70. The Effect of Alcohol upon the Bony Framework.
During the entire period of bone growth the nutrition of
the body should not be impaired.1 The bones should be
furnished with all the materials necessary for a large and
durable framework. Otherwise the body will be feeble
and stunted in growth. This condition is seen in the
stunted stature of young persons who have been underfed
and overworked. It is believed that alcoholic liquors

1 Alcohol retards the growth of young cells and prevents their proper
development. Alcohol in all its forms is particularly injurious to young
persons, as it retards their growth and stunts both body and mind. This
is the theory of Dr. Lionel S. Beale, a celebrated microscopist and thinker,
and is quite generally accepted. — DR. ROGER S. TRACY of the New York
Board of Health.

The Framework of the Body 47

before maturity may produce a similar effect, hindering
the full activity of bone cell-growth and thus preventing
full development of the bones.

Surgeons recognize the fact that the broken bones of
drunkards usually unite with greater difficulty than do those
of the average patient. The use of alcoholic liquors is also
one of the most frequent predisposing causes of the serious
and painful disease known as gout, which often attacks the
joints.

71. Effect of Tobacco upon the Bony Tissues. Powerful
narcotics, like tobacco and opium, by retarding the activity
of bone cell-growth, hinder the building up of the bodily
frame. The formation of healthy bone tissue demands
good, nutritious blood ; but if this vital tissue is loaded with
poisonous narcotics, the bones are defrauded of their proper
building material.

ADDITIONAL EXPERIMENTS

Experiment 15. To illustrate the movement of torsion in the spine,
or its rotation round its own axis. Sit upright, with the back and
shoulders well applied against the back of a chair. Note that the
head and neck can be turned as far as 60° or 70°. Now bend for-
ward, so as to let the dorsal and lumbar vertebrae come into play,
and the head can be turned 30° more.

Experiment 16. To show how the spinal vertebra make a firm
but flexible column. Take twenty-four hard-rubber overcoat buttons,
or the same number of coins, and pile them on top of one another.
A thin layer of soft putty may be put between the coins to represent
the pads of cartilage between the vertebrae. The most striking
features of the spinal column may be illustrated by this simple
apparatus.

NOTE. — As the succe'eding chapters are studied, additional experiments
on bones and their relation to other parts of the body will readily sug-
gest themselves to the ingenious instructor or the thoughtful student. Such
experiments may be utilized for review or other exercises.

THE BONES OF THE BODY

'

i Frontal

2 Parietal

I. CRANIUM 1

2 Temporal

(8 bones) / '

i Occipital

i Sphenoid

i Ethmoid

2 Superior Maxillary

2 Malar

THE HEAD

2 Nasal

(29 bones)

II. FACE 1

(14 bones) J

2 Lachrymal
2 Palate

2 Turbinated

i Vomer

i Lower Maxillary

III. THE EAR!

[Hammer
Anvil

(6 bones) j '

Stirrup

IV. HYOID BONE

7 Cervical Vertebrae

THE TRUNK

I. SPINAL COLUMN^

(26 bones) j

12 Dorsal Vertebras
5 Lumbar Vertebras
Sacrum
Coccyx

(53 bones)

II. THE RIBS "1 | 14 True Ribs
(24 bones) J 1 I0 False Ribs

III. STERNUM

IV. Two HIP BONES

I. SHOULDER .

Scapula

1

Clavicle

UPPER LIMBS

II. ARM

Humerus

(64 bones)

III. FOREARM . . . J

:Ulna
Radius

IV HAND J

8 Carpal
5 Metacarpal

1

14 Phalanges

I. THIGH ....

Femur

1

Tibia

LOWER LIMBS

II. LEG . . J

Fibula

(60 bones)

1

Patella

f

• 7 Tarsal

III. FOOT ... J

5 Metatarsal
14 Phalanges

CHAPTER III
THE MUSCLES

A 72. Spontaneous Movements in Animals. Trees and
stones never move unless acted upon by external force,
while the infant and the tiniest insect can execute a great
variety of movements. When the higher animals are at
rest it is possible to observe some kind of motion in them.
Even in the deepest sleep the beating of the heart and the
motion of the chest never cease. In fact, the power to
execute spontaneous movements is the most distinctive property
of living animals.

All motion of our bodies is produced by means of
muscles. Not only the limbs are moved by them, but even
the movements of the stomach and of the heart are caused
by muscles. Every part of the body which is capable of
motion has its own special set of muscles.
_3 73. The Two Great Kinds of Muscles. All the move-
ments of the body as a whole are performed by muscles.
These muscles make up the red flesh, well known to
every one as the lean of butcher's meat, which, together
with the fat, clothes the bony framework. We often call
these voluntary muscles, because they are more or less
subject to the control of the will.

The motion of the internal organs, as those of digestion,
secretion, excretion, circulation, and respiration, are pro-
duced by muscles of another kind, that is, by muscles not
usually under the control of' the will. This work goes on

49

Life and Health

quite independently of the will, and even during sleep. We
frequently call the instruments of this activity involuntary
muscles.

The former group, or skeletal muscles, from peculiarities
revealed by the microscope, are more accurately known as
striped or striated muscles. The latter group, or visceral
muscles, from the smooth appearance
which their cells present under the micro-
scope, are called unstriated muscles.

Let us then remember the two kinds
of muscles as the striated (often called
voluntary) muscles, and the smooth, unstri-
ated (often called involuntary) muscles.

74. Structure of the Striated Muscle.
The main substance which clothes the
bony framework of the body, and which
forms about two-fifths of its weight, is
the striated muscular tissue. These
skeletal muscles do not cover and sur-

A, fiber separating into

disks; B, fibriiis (highly round the bones in continuous sheets,
magnified); Across- but consist of separate bundles of flesh,

section of a disk. ...

varying in size and length.

Each muscle has its own set of blood vessels and nerves,
and is enveloped in its own sheath of connective tissue,
known as the perimysium. When this external wrapping is
strong enough to be dissected off, it is known as fascia.

Muscles are not usually connected directly with bones, but
by means of white, glistening cords or bands, called tendons.

75. Microscopic Structure of Striated Muscle. If a small
piece of striated muscle be examined under a microscope
it is found to be made up of bundles of fibers. Each fiber
is enclosed within a delicate, transparent sheath, known as
the sarcolemma. If one of these fibers be further examined

FIG. 29. Striated
Muscular Fibers.

The Muscles

lit

1

SSHH

BMS5I

under a very powerful microscope, it will sometimes be
seen to consist of a great number of still more minute
fibers, called fibrillae. These fibers are also seen marked
crosswise with dark stripes and can be separated at each
stripe into disks. These cross-markings account for the
name striped, or striated, muscle.

The fibrillae, then, are bound together
in a bundle to form a fiber, which is
enveloped in its own sheath, the sar-
colemma. These fibers, in turn, are
further bound together to form larger
bundles, called fasciculi, and these, too,
are enclosed in a sheath of connective
tissue. The muscle itself is made up
of a number of these fasciculi bound
together by an external wrapping (peri-
mysium) of connective tissue.

76. Structure of the Unstriated Muscle.

_,, , . , f ., , , , A, muscular fiber, show-

These muscles consist of ribbon-shaped ing stripes; ^and^
bands which surround hollow, fleshy nuclei. (Highly mag-
tubes or cavities. As they are never
attached to bony levers, they have no need of tendons.
The microscope shows that these muscles consist not of
fibers, but of long, spindle-shaped cells, united to form
sheets or bands. They have no sarcolemma, stripes, or
cross-markings like those of the striped muscles. Hence
their name of unstriated, or unstriped, and smooth muscles.

Experiment 17. To show the gross structure of muscle. Take
a small portion of a large muscle, as a strip of lean corned beef.
Have it boiled until its fibers can be easily separated. Pick the
bundles and fibers apart until they are so fine as to be almost
invisible to the naked eye. Continue the experiment with the help
of a hand magnifying glass or a microscope.

FIG. 30.

52

Life and Health

77. Action of the Unstriated Muscles. The unstriated
muscles respond to irritation much less rapidly than do
the striated. The wave of contraction passes over them
more slowly and more irregularly, one part contracting
while another is relaxing. This may readily be seen in the
muscular action of the intestines, called •vermicular motion,
or peristalsis. Irregular and excessive
contraction of the muscular walls of the
bowels produces the cramp-like pains of
colic.

Experiment 18. To show the general appear-
ance of the muscles. Obtain the lower part of
a sheep's or calf's leg, with most of the lean
meat and the hoof left on. One or more of the
muscles, with their bundles of fibers, fascia,
and tendons, are readily made out with a little
careful dissection.

The dissection should be made a few days
before it is wanted and the parts allowed to
harden somewhat in dilute alcohol.

FIG. 31. A Spindle
Cell of Involuntary
Muscle.
(Highly magnified.)

In the stomach the contraction of these
muscles produces the motion by which
the food is churned about ; in the arteries
and veins they regulate the size of the channels through
which the blood is driven along, and in the intestines they
supply the force by which the partly digested food is mainly
kept in motion.

J 78. Muscular Contractility. The most characteristic
property of muscle in the living state is its contractility,
or the power of shortening when irritated by a stimulus,
its volume or bulk remaining the same. In brief, when a
muscular fiber contracts, it tends to bring its two ends
closer together.

The Muscles

53

FIG. 32. Superficial Muscles of the Body. (Front view.)

54 Life and Health

Muscles are almost invariably stimulated to contraction
by a nervous impulse. The delicate nerve fibrils which end
in the muscle fibers communicate with the spinal cord or
the brain, the center of the will power. Hence, when the
brain commands, a nervous impulse, sent along the nerve
fibers, becomes the exciting stimulus which acts upon the
muscles and makes them contract.1 If the nerves of a
part, as the face or the leg, be severed the muscles will
fail to act, because while they are intact and ready
to work, there are no means of sending commands
to them and they remain idle. In short, the parts are
paralyzed.

Contraction is not, however, the natural state of a
muscle. In time it is tired and begins to relax. Even
the heart, the hardest-working muscle, rests between its
beats.

479. The Object of Contraction. The object of contrac-
tion is obvious. If one end of a muscle be fixed and the
other attached to some object which is free to move, the
contraction of the muscle will bring the movable body
nearer to the fixed point. Thus by their contraction muscles
are able to do work. They even contract more vigorously
when resistance is opposed to them than when it is not.
If, however, the contractions are too rapid or too long con-
tinued the muscles become exhausted. When the feeling
of exhaustion passes away with rest, the muscle recovers
its power.

1 This property of contraction is inherent and belongs to the muscle
itself. It is often independent of the brain. Thus, on pricking the heart
of a fish an hour after removal from its body, obvious contraction will
occur. In this case it is not the nerve force from the brain that supplies
the energy for contraction. The power of contraction is inherent in the
muscle substance, and the stimulus by irritating the nerve ganglia of the
heart simply affords the opportunity for its exercise.

The Muscles 55

A 80. Various Kinds of Muscles. There are about four
hundred muscles in the human body, all necessary for its
various movements. They vary greatly in shape and size,
according to their position and use. Some are from one
to two feet long, others only a fraction of an inch. Some
are long and spindle-shaped, others thin and broad, while
still others form rings. Thus, some of the muscles of the
arm and thigh are long and tapering, while the abdominal
muscles are thin and broad. Again, the muscular fibers
which surround and by their contraction close certain
orifices, as those of the eyelids and lips, sometimes radiate
like the spokes of a wheel, and sometimes form complete
circles or ellipses.

The part of. a muscle which remains fixed when it
contracts is called its origin ; the end connected with the
movable part is its insertion.

81. ' How Muscles are named. Muscles are named accord-
ing to their shape, position, division of origin or insertion,
and their function. Thus we have the recti (straight) and the
deltoid (A, delta), the brachial (arm), pectoral (breast), and the
intercosials (between the ribs), so named from their position.
Again, we have the biceps (two-headed), triceps (three-headed),
and many others with similar names, so called from the points
of origin and insertion. We find other groups named after
their special use. The muscles which 'bend the limbs are
called flexor s, while those which straighten them are known as
extensors.

Experiment 19. To show how muscles relax and contract. Lay
your left forearm on a table ; grasp with the right hand the mass of
flesh on the front of the upper arm. Now gradually raise the fore-
arm, keeping the elbow on the table. Note that the muscle thickens
as the hand rises. This illustrates the contraction of the biceps, and
is popularly called "trying your muscle." Reverse the act Keep
the elbow in position, bring the forearm slowly to the table, and the
biceps appears to become softer and smaller, — it relaxes.

Life and Health

^82. Tendons and their Work. The fleshy parts of
muscles are not usually connected directly with bones.
The mass of flesh tapers off towards the ends, where the
fibers pass into white, glistening cords, known as tendons.

These are commonly very strong,
made up of white, fibrous tissue,
and may be compared to ropes or
cords which, when pulled, are made
to act upon distant objects to which
one end is fastened.

Tendons are most numerous
about the larger joints, where
they permit free action and yet
occupy but little space. If we
bend the arm or leg forcibly and
grasp the inside of the elbow or
knee joint, we can feel the ten-
dons beneath the skin. The
numerous tendons in the palm
or on the back of the hand
contribute to its marvelous dex-
terity.

The thickest and strongest ten-
don in the body is the tendon of
Achilles, which connects the great

The Biceps Muscle dissected mUScleS in the Calf °f the leS with

to show its Tendons. the heel bone.

FIG. 33.

Experiment 20. Repeat Experiment 19 with other muscles. With
the right hand grasp firmly the extended left forearm. Extend and
flex the fingers vigorously. Note the effect on the muscles and
tendons of the forearm. Grasp with the right hand the calf of the
extended right leg, and vigorously flex the leg, bringing it near to
the body. Note the contractions and relaxations of the muscles.

The Muscles 57

83. Synovial Sheaths and Sacs. The rapid movement of
the tendons over bony surfaces would soon produce an undue
amount of heat and friction unless some means were provided
to make the parts run smoothly. This is supplied by sheaths
which form a double lining around the tendons. The opposed
surfaces are lined with synovial membrane, the secretion from
which moistens the sheaths in which the tendons move.

Little closed sacs, called synovial sacs, or bursae, similarly
lined and containing fluid, are also found in special places
between two surfaces where much motion is required. Thus,
there are two of these bursae near the patella. Without these,
the constant motion of the knee-pan in walking would produce
undue friction and heat.

Experiment 21. Examine carefully the tendons in the parts dis-
sected in Experiment 18. Pull on the muscles and the tendons, and
note how they act to move the parts. This may be also admirably
shown on the leg of a fowl or turkey obtained from a kitchen or from
the market.

Obtain the hoof of a calf or sheep with one end of the tendon of
Achilles still attached. Dissect it and test its strength.

Experiment 22. The tendons which bound the space behind the
knee can be distinctly felt when the muscles which bend the knee are
in action. On the outer side note the tendons of the biceps of the
leg, running down to the head of the fibula. On the inside we feel
three tendons of important muscles on the back of the thigh which
flex the leg upon the thigh.

A 84. The Mechanics of Motion. Levers. The active agents
of bodily movements, as we have seen, are the muscles.
All these movements, both of motion and of locomotion,
are regulated according to certain fixed laws of mechanics.
The bones, to which a great proportion of the muscles in
the body are attached, act as distinct levers. The muscles
supply the power for moving the bones, and the joints act
as fulcrums or points of support. The weight of the limb,
the weight to be lifted, or the force to be overcome, is the
resistance.

58 Life and Health

85. Examples of Levers in the Body. In mechanics three
classes of levers are described, according to the relative posi-
tion of the power, the fulcrum, and the weight, or the resistance.
The movements of the bones can be referred to one or another
of these three classes.

The head is supported on the atlas by a lever of the first
class. The joint between the atlas and the skull is the fulcrum,
the weight of the front of the head is the resistance. The
power is behind, where the muscles from the neck are attached
to the back of the skull. The object of this arrangement is to
keep the head steady and balanced on the spinal column,

w FPF WPFP w

FIG. 34. Diagram illustrating Three Kinds of Lever Action.

F, fulcrum; P, power; W, weight. In the left-hand diagram the head is tilted
back by the muscles of the neck. In the middle figure the toes rest on the
ground, and the body is raised by the leg muscles. In the right-hand diagram
the forearm is bent up by the biceps muscle.

and to move it backward and forward. Range and rapidity
are here gained at the expense of power.

Standing on tiptoe is done by means of a lever of the second
class. The toes in contact with the ground are the fulcrum,
the power is the action of the muscles of the calf, and between
these is the weight of the body transmitted down the bones
of the leg to the ankle. Power is here gained at the expense
of range of movement.

Levers of the third class are common in the body. In
bending the forearm on the arm, familiarly known as "trying
your muscle," the power is supplied by the biceps muscle
attached to the radius, the fulcrum is the elbow joint at one
end of the lever, and the resistance is the weight of the fore-
arm and hand at the other end.

The Muscles 59

86. Muscles of the Head and Neck. There are scores
of tiny muscles about the head, face, and eyes, which by
their alternate contractions and relaxations impart to the
countenance those expressions which reflect the feelings
and passions of the individual.

Two important muscles, the temporal, near the temples,
and the masseter, or chewing muscle, are the chief agents
in moving the lower jaw. They are very large in the lion,
tiger, and other flesh-eating animals. On the inner side of
each cheek is the buccinator, or trumpeter's muscle, which
is largely developed in those who play on wind instruments.
Easily seen and felt under the skin in thin persons, on
turning the head to one side, is the sterno-cleido-mastoid
muscle, which passes obliquely down on each side of the
neck to the collar bone. This muscle is prominent in
sculpture and painting.

Experiment 23. To ilhistrate how the muscles use the bones as
levers. First, practice with a ruler, blackboard pointer, or any other
convenient object, illustrating the different kinds of levers, until the
principles are familiar. Next, illustrate these principles on the per-
son, by making use of convenient muscles. Thus, lift a book on the
toes, by the fingers, on the back of the hand, by the mouth, and
in other ways.

Experiment 24. With the head slightly bent forward, grasp
between the fingers and thumb of the right hand the edge of the
left sterno-cleido-mastoid muscle, just above the collar bone. Raise
the head and turn it from left to right, and the action of this
important muscle is readily seen and felt.

87. Muscles of the Chest and Back. The chest is sup-
plied with numerous muscles which move the ribs up and
down in the act of breathing. A great fan-shaped muscle,
called the pectoralis major, lies on the chest. It extends from
the chest to the arm and helps draw the arm inward and

6o

Life and Health

forward. At the back of the shoulder a large, spread-out
muscle passes upward from the back to the humerus.
From its wide expanse on the back it is known as the
latissimus dorsi ("broadest of the back"). When in action

FIG. 35. Principal Muscles on the Left Side of Neck.

A, buccinator; ff, masseter; C, depressor anguli oris; D, anterior portion of the
digastric; E, mylo-hyoid ; F, tendon of the digastric ; G, sterno-hyoid ; //, sterno-
thyroid; K, omo-hyoid; /., sternal origin of sterno-cleido-mastoid muscle;
M, superior fibers of deltoid; N, posterior scalenus; O, clavicular origin of
sterno-cleido-mastoid ; P, sterno-cleido-mastoid ; R, trapezius ; S, anterior con-
strictor ; T, splenius capitis ; V, stylo-hyoid ; W, posterior portion of the
digastric; X, fasciculi of ear muscles; Z, occipital.

it draws the arm downward and backward, or, if one hangs
by the hands, it helps to raise the body. It is familiarly
known as the " climbing muscle."

The Muscles 61

88. Muscles of the Shoulder and Arm. The arm is raised
from the side by a large triangular muscle on the shoulder,
the deltoid, so called from its resemblance to the Greek
letter delta, A. The biceps, or two-headed muscle, forms a
large part of the fleshy mass in front of the arm. Its use
is to bend the forearm on the arm, an act familiarly known
as " trying your muscle." Its direct antagonist is the
three-headed muscle, called the triceps. This forms the
fleshy mass on the back of the arm, its use being to draw
the flexed forearm into a right line.

On the back and outside of the forearm are the extensors,
which straighten the wrist, the hand, and the fingers. On
the front and inside of the forearm are the flexors, which
bend the hand, the wrist, and the fingers. If these muscles
are worked vigorously, their tendons can be readily seen
and felt under the skin.

89, Muscles of the Lower Extremities. Passing to the
lower extremities, the thigh muscles are the largest and
the most powerful in the body. In front a great, four-
headed muscle, quadriceps extensor, unites into a single tendon
in which the knee-cap is set, and serves to straighten the
knee, or when rising from a sitting posture helps elevate
the body. On the back of the thigh are several large mus-
cles which bend the knee, and whose tendons, known as
the " hamstrings," are readily felt just behind the knee.

On the back of the leg the most important muscles,
forming what is known as the calf, are the gastrocnemius
and the soleus. The first forms the largest part of the
calf. The soleus, so named from its fancied resemblance
to a sole-fish, is a muscle of broad, flattened shape, lying
beneath the gastrocnemius.

The tendons of these two muscles unite to form the
tendon of Achilles, so called because that hero is said to have

62 Life and Health

been invulnerable except at this point. The muscles of
the calf of the leg have great power, and are constantly
called into use in walking, cycling, dancing, and leaping.

FIG. 36. A Few of the Important Muscles of the Back.

90. Effect of Alcoholic Beverages upon Muscular Work.
Alcohol, even in small quantities, tends to depress the
nervous centers, and thus indirectly relaxes the muscles.

The Muscles 63

This is evident from the unsteady hand, the staggering
gait, and the lack of general muscular control of those
who are under the influence of strong drink.

Men under the influence of alcoholic liquor may do an
increased amount of muscular work for a very few minutes,
but such an increase is produced at the expense of energy
which is needed in enduring sustained exposure or work.
Men who are trained for athletic contests are strictly for-
bidden to use alcoholic beverages.

In brief, while a certain amount of energy may be
derived from the oxidation of alcohol in the body, both
experiment and observation seem to show that the sum
total of benefit in the form of sustained muscular work is
more than counterbalanced by the paralyzant effect of the
alcohol upon the nervous system.

91, Effect of Tobacco on the Muscular Tissues. Tobacco
tends to impair the energy of the muscular tissues as alco-
hol does, by its paralyzing effect upon the nervous centers.
This applies especially to the young, in the growing age
between twelve or fourteen and twenty, the very time
when the healthy body is being well knit and compacted.

Hence many public and private schools, as well as our
national naval and military academies, rigidly prohibit the
use of tobacco by their students.

For the same reason, the statute laws in many states
prohibit the sale of cigarettes to minor children.

Several directors of physical education in our colleges
have clearly demonstrated by personal examination and
recorded statistics that the use of tobacco among college
students checks growth in weight, height, chest-girth, and,
most of all, in lung capacity.

64 Life and Health

ADDITIONAL EXPERIMENTS

Experiment 25. To examine the minute structure of voluntary
muscular fiber. Tease, with two needles set in small handles, a bit
of raw, lean meat, on a slip of glass, in a little water. Continue
until the pieces are almost invisible to the naked eye.

Experiment 26. Place a clean, dry cover-glass, of about the width
of the slip, over the water containing the torn fragments. Absorb
the excess of moisture at the edge of the cover by pressing a bit
of blotting paper against it for a moment. Place it on the stage
of a microscope and examine with highest obtainable power, by
light reflected upward from the mirror beneath the stage. Note the
apparent size of the finest fibers ; the striation of the fibers, or mark-
ings of alternate dim and bright cross bands.

/Experiment 27. To show the ligamentous action of the muscles.
Standing with the back fixed against a wall to steady the pelvis, the
knee can be flexed so as almost to touch the abdomen. Take the
same position and keep the knee rigid. When the heel has been but
slightly raised a sharp pain in the back of the thigh follows any
effort to carry it higher. Flexion of the leg to a right angle increases
the distance from the lines of insertion on the pelvic bones to the
tuberosities of the tibia by two or three inches — an amount of
stretching these muscles cannot undergo. Hence the knee must be
flexed in flexion of the hip.

Experiment 28. A similar experiment may be tried at the wrist.
Flex the wrist with the fingers extended, and again with the fingers
in the fist. The first movement can be carried to 90 per cent, the
second only to 30 per cent, or in some persons up to 60 per cent.
Making a fist had already stretched the extensor muscles of the arm,
and they can be stretched but little farther. Hence, needless pain
will be avoided by working a stiff wrist with the parts loose, or the
fingers extended, and not with a clenched fist.

NOTE. — A description of an apparatus, illustrating the combined
action of muscles and joints, may be found in the Outlines of Require-
ments for Harvard University.

IMPORTANT MUSCLES OF THE BODY

LOCATION

HEAD

AND

NECK

TRUNK

UPPER
LIMBS

LOWER
LIMBS

NAME

Occipito-frontalis . .

Obicularis palpebrarum
Levator palpebrarum .

Temporal

Masseter .

Sterno-cleido-mastoid .
Platysma myoides

Pectoralis major . .
Pectoralis minor . .
Latissimus dorsi . .

Serratus magnus . .
Trapezius ....
Rhomboideus . . .
Intercostals ....
External oblique . .
Internal oblique . .

Rectus abdominis . .

Deltoid

Biceps
! Triceps
I Brachialis anticus

Supinator longus .

Flexor carpi radialis
1^ Flexor carpi ulnaris

Gluteus maximus .
Adductors of thigh
Sartorius

Rectus femoris . .

Vastus externus .

Vastus internus .

Biceps femoris . .

Gracilis . . .

Tibialis anticus
Peroneus longus
Gastrocnemius .
Soleus .

CHIEF FUNCTION

moves scalp and raises eye-
brow.

shuts the eyes,
opens the eyes.

raise the lower jaw.

depresses head upon neck and

neck upon chest,
depresses lower jaw and lower

lip.

draws arm across front of

chest.

depresses point of shoulder,
draws arm downwards and

backwards.

assists in raising ribs,
backward movements of head

and shoulder,
raise and depress the ribs,
various forward movements

of trunk,
compresses abdominal viscera

and acts upon pelvis.

carries arm outwards and up-
wards.

flexes elbow and raises arm.
extends the forearm,
flexor of elbow,
flexes the forearm.

flexors of wrist.

adducts the thigh.

draw the thigh inwards.

crosses the legs.

extensor of leg.

extensor of leg.

extensor of leg upon thigh.

flexes leg upon thigh.

flexes the leg and adducts

thigh.

draws up inner border of foot,
raises outer edge of foot,
keep the body erect, and aid

in walking and running.

CHAPTER IV
PHYSICAL EXERCISE

92. Practical Importance of Sound Physical Health. A
healthy and vigorous child is never still except during sleep.
The restless muscles of school children pent up for several
hours feel the need of movement, as a hungry man craves
food. The gratification of this natural desire for muscular
exercise is essential to the full development and perfect
maintenance of the bodily health. Nothing is so essential
to success in life as sound physical health. It enables us to
work with energy and comfort and to endure unusual physi-
cal and mental strains. While others suffer the penalties
of feebleness, a lower standard of functional activities, and
premature decay, the fortunate possessor of a sound mind
in a sound body is prepared, with proper application, to
endure the hardships and win the triumphs of life.

93. Effect of Exercise upon the Muscles. Systematic
exercise promotes the growth and development of the
muscles in a somewhat remarkable manner. Muscles

NOTE. — There is no profession, there is no calling or occupation
in which men can be engaged, there is no position in life, in which a
fairly developed frame will not be valuable ; there are many of these,
even the most purely and highly intellectual, in which it is essential
to success. Year by year, almost day by day, we see men and women
falter and fail in the midst of their labors ; . . . and all for want of
a little bodily stamina — a little bodily power and bodily capacity for
the endurance of fatigue, or protracted unrest, or anxiety, or grief. —
MACLAREN'S Physical Education.

66

Physical Exercise

properly exercised not only increase in size, but are better
enabled to get rid of any needless accumulation of fat,
as well as useless waste matters,
which may exist in the tissues.

Muscular exercise provides the
joints with more powerful liga-
ments and better developed bony
parts. After long confinement to
the bed from disease, the joints
have wasted ligaments, thin carti-
lages, and the bones are of smaller
proportions.

94, Muscular Coordination and
Physical Training. He who has
been physically well trained has
both a more economical and a
more intelligent use of his mus-
cles. He has acquired the art of
causing his muscles to act in har-
mony. Movements once difficult
are now carried on with ease.
The power of coordination is
increased, so that a desired end
is attained with the least expendi-
ture of physical force and nervous
energy. In learning to row, play
baseball, ride the bicycle, or in
any other exercises, the beginner makes his movements
in a stiff and awkward manner. He will use and waste
more muscular force in playing one game of ball, or in
riding a mile on his wheel, than an expert would in doing
many times the work. He has not yet learned to balance
one set of muscles against its antagonists.

FIG. 37. The Standard
Special Chest Weight.

(A convenient machine by means
of which all the muscles of the
body may be easily and pleas-
antly exercised, with sufficient
variations in the movements to
prevent monotony. A space
about 6 ft. wide, 6 ft. deep, and
7 ft. high is required in exercis-
ing with this machine.)

68 Life and Health

In time, however, acts which were first done only with
effort, and by a conscious will, become automatic. The
will ceases to concern itself. By what is called reflex action,
habit is developed in the nerve centers of the spinal cord.
There is thus a great saving of actual brain work, and one
important cause of fatigue is removed.

95. Effect of Exercise on the Circulation and Respiration.
As the action of the heart is increased both in force and
in frequency during exercise, the flow of blood throughout
the body is augmented. This results from the force of
the muscular contractions which play their part in press-
ing the blood in the veins onward towards the heart.

Exercise also induces a more vigorous respiration, and
under increased breathing efforts the lung capacity is
increased and the size of the chest is enlarged. The
amount of air inspired and expired in a given time is
much larger than if the body were at rest. The blood
is thus supplied with a much larger amount of oxygen from
the air inhaled, and gives off to the air a corresponding
excess of carbon dioxide and water.

96. Effect of Exercise on Digestion. Exercise stimulates
and strengthens the organs of digestion. The appetite is
improved, especially after exercise in the open air. The
digestion is more complete, absorption becomes more rapid,
the peristaltic movements of the bowels are promoted, and
the circulation through the liver is more vigorous.

Ample exercise also checks the tendency so common
with those who eat heartily, but lead sedentary lives,
towards a torpid circulation in the larger digestive organs,
especially in the stomach and the liver.

97. Exercise and the Bodily Temperature. Exercise
increases the flow of blood through the small vessels of
the skin, and thus increases the radiation of heat' from

Physical Exercise

the surface. If the exercise be vigorous and the weather
hot, a profuse perspiration ensues, the rapid evaporation of
which cools the body. The skin is thus a most important
regulator of the bodily temperature, and prevents any
harmful rise above the normal
which would otherwise result
from vigorous exercise.

98, Effect of Physical Train-
ing upon the Personal Appear-
ance. Judicious and systematic
exercise, if moderately employed,
soon gives a more upright and
symmetrical figure, and an easier
and more graceful carriage.
Rounded shoulders become
square, an awkward gait dis-
appears, and there is seen a
graceful poise of the head and
a bearing of the body which
marks those whose muscles have
been well trained. Exercise
improves the condition of the
tissues generally. They become
more elastic, and in all respects
sounder. The skin becomes
firm, clear, and healthy.

The delicate, ruddy aspect
of the complexion, the swing of
the body and the bearing of the

FIG. 38. Young Woman prac-
ticing at Home with the
" Whitely Exerciser."
(From a photograph.)

head and shoulders of young women whose physical training has
been efficient are in marked contrast with the characteristics of
those whose education in this respect has been neglected.

99. Unsuitable or Excessive Exercise. Exercise, like
everything else which promotes our welfare, may be car-
ried to excess. The words "excessive" and "unsuitable,"
when applied to muscular exertion, are relative terms, and
apply to the individual rather than to the amount of work

7° Life and Health

done. What may be excessive for one person might be
beneficial to another.

Breathlessness is, perhaps, the most common effect 'of
undue exertion. Let a middle-aged person, who is out of
practice, run even a short distance, and he is soon troubled
with his breathing. He pants, and his strength gives out.

FIG. 39. A Well-Equipped Gymnasium.
(From a photograph.)

His chest, and not his legs, has failed him. He is said to
be "out of breath."

The heart is often overstrained during violent exertion, as
in lifting a great weight. Certain forms of heart disease
are common with those whose occupations involve severe
muscular effort, as professional athletes and oarsmen.

100. Results of Excessive Muscular Movements. The
excessive repetition of muscular movements may lead to

Physical Exercise 7 1

permanent contractions of the parts involved. Thus sailors,
mechanics, and others frequently develop a rigidity of the
tendons of the hand which prevents the full extension of
the fingers. So stenographers, typewriters, telegraphers,
and writers occasionally suffer from permanent contractions
of certain muscles of the arm, known as writer's cramp.

101. Muscular Fatigue. We all know how tiresome it
is to hold the arm outstretched horizontally even for a few
moments. A single muscle, the deltoid, in this case does
most of the work. Even in a vigorous man this muscle
can act no longer than four to six minutes before the arm
drops helpless. We may prolong the period by a strong
effort of the will, f but a time soon comes when no possible
effort will enable us to hold out the arm. The muscle is
said to be fatigued. It has by no means lost its contractile
power, for if we apply a strong electric stimulus to it, the
muscle will contract again. In brief, the functional power
of a muscle has a definite limit, and in fatigue that limit is
reached.

„ 102. Results of Muscular Fatigue. The strength of the
muscle, its physical condition, the work it has done, and
the mental condition of the individual, all modify the state
of fatigue. In those difficult acts .which involve a spe-
cial effort of the will, the question of nerve exhaustion is
largely concerned.

Thus, the incessant movements in St. Vitus' dance
result in comparatively little fatigue, because there is no
association of the brain with the muscular / action. If a
strong man should attempt to perform voluntarily the
same movements, he would soon have to rest. None of
the movements which are performed independently of the
will, as the heart beats and breathing movements, ever
involve the sensation of fatigue.

72

Life and Health

As a result of fatigue the normal irritability of muscular
tissue becomes weakened, and its force of contraction is
lessened. There is, also, often noticed in fatigue a peculiar
tremor of the muscles, rendering their movements uncertain.
The stiffness of the muscles which occurs during severe
exercise, or the day after, is a familiar result of fatigue.

103. Fatigue serves
as Nature's Warning.
The sense of fatigue is
Nature's warning to put
us on our guard. It is
a kind of regulator which
serves .in the ordinary
actions of life to warn us
not to exceed the limits
of useful exercise.
Fatigue summons us to
rest long before all the
force of the motor organs
has been expended, just
as the sensation of hun-
ger warns us that we
need food, long before
the body has become weak from the lack of nourishment.
104. A Period of Rest Necessary. Rest is necessary for
the tissues, that they may repair the losses sustained in
doing work. A period of rest must alternate with a period
of activity. Even the heart has its periods of absolute
rest to alternate with those of work. Were it not for this
power to repair and renew its tissues, the body would soon
be worn out.

The periods of rest should vary with the kind of exercise.
Thus, exercise which produces breathlessness requires

FIG. 40. Showing how the Muscles of
the Back may be developed by a
Moderate Amount of Dumb-Bell Exer-
cise at Home.
(From a photograph of the living model.)

Physical Exercise 73

frequent but short rests. The trained runner, rinding his
respiration embarrassed, stops a moment to regain his
breath. Exercises of endurance cause fatigue less quickly
than those of speed, but require longer rest.

105. Amount of Physical Exercise required. The amount
of physical exercise that can be safely performed by each
person is a most important and practical question. No
rule can be laid down, for what one person bears well may
prove very injurious to another. To a certain extent, each
must be guided by his own judgment. If, after taking
exercise, we feel fatigued and irritable, are subject to head-
ache and sleeplessness, or find it difficult to apply the mind
to our work, it is plain that we have been taxing our
strength unduly, and the warning should be heeded.

It may be laid down as a fairly safe rule that an adult
of average height and weight, engaged in study or in any
indoor or sedentary occupation, should take an amount
of exercise equivalent to walking five or six miles a day.
Growing children, as a rule, take more exercise than this,
while most men working indoors take far less, and many
women take less exercise than men. Exercise may be
varied in many ways, the more the better ; but as far as
possible it should be taken in the open air.

106. Amount of Exercise modified by Circumstances.
The proper amount of exercise must vary greatly with
circumstances. Thus, age is an important factor in the
problem. A young man may do with ease and safety
what might be injurious to an older person. In youth,
when the body is developing most rapidly, the judicious
use of games, sports, and gymnastics is most beneficial.

Abundant evidence shows that physical development is
most active from the thirteenth to the seventeenth year;
this manifests itself clearly by increase in weight. Hence,

74

Life and Health

this period of life is of great importance in the physical
development of the body. If at this age a boy or girl is
subjected to undue physical strain, the development may
suffer, the growth be retarded, and the foundation laid for
future ill health.

107. Time for Exercise. It is not prudent to do hard
work or take severe exercise just before or just after a full

meal. While the
stomach is busily
digesting food vigor-
ous exercise may
prove injurious, and
is apt to result sooner
or later in dyspepsia.
Hence the best time
to take exercise is
one or two hours
after a meal.

On the other
hand, severe exer-
cise should not be
taken on an empty
stomach. Those
who do much work
or study before
breakfast should first take a light lunch, just enough to
prevent any faint feeling. With this precaution, there
is no better time for moderate exercise than the early
morning.

108. Walking, Running, and Jumping. Walking is gen-
erally regarded as the simplest and most convenient mode
of taking exercise. When taken with a special object in
view, it is the best and most pleasant of all physical

FIG. 41. Student exercising in the School

Gymnasium on the Rowing Machine.

(From a photograph.)

Physical Exercise

75

activities. It is suited to individuals of all ages and occu-
pations, and to residents of every climate.

In walking, the muscles of the entire body are brought into
action, and the movements of breathing and the circulation
of the blood are increased. The body should be erect, the
chest thrown out, the head and shoulders held back, and
the stride long and elastic. It is an excellent custom to
add to the usefulness of this fine exercise by deep, voluntary
inhalations of pure air.

Running as an exercise is beneficial to those who have kept
themselves in practice and in sound condition. It brings
into play nearly every muscle of the body, and thus serves
to develop the power of
endurance, as well as
strength and capacity for
rapid movement.

Jumping is usually an
admirable and beneficial
form of exercise. It
brings into action many
muscles without putting
undue strain upon any
particular group.

109. Skating, Swim-
ming, and Rowing.
Skating is a delightful
and invigorating exercise.
It calls into play a great
variety of muscles, and is
beneficial at almost all ages. It strengthens the ankles and
helps give an easy and graceful carriage to the body.

Every child above ten years of age should be taught
to swim. The art, once mastered, is never forgotten. It

FIG. 42. Showing how Muscles may be
developed in Rowing.

(Based upon a photograph from the
living model.)

76 Life and Health

calls into action a wide combination of muscles. This
accomplishment, so easily learned, should be a part of our
education, as it may be the means of saving one's own life
or that of a companion.

In many respects rowing is one of the most perfect exer-
cises at our command. It expands the chest, strengthens
the body, and gives tone to the muscles of the abdomen.
It is an admirable exercise for girls and women.

110. The Use of the Bicycle. The bicycle is at once the
most useful and the most attractive machine ever devised
for use and pleasure. Nothing has ever approached the
wheel in tempting persons of all ages and occupations to
go out of doors and take vigoious exercise.

Bicycling does not bring into active use the leg muscles
alone. It also produces a substantial increase in the cir-
cumference of the chest. It causes the arms and forearms
to grow firmer and the muscles of respiration to become
stronger and larger. In fact, the muscles of the whole
body seem to improve in tone with this form of exercise.

111. Outdoor Games and Physical Education. While
outdoor games are not necessary to maintain health, yet
we can scarcely overestimate the value and usefulness of
baseball, football, tennis, golf, and croquet in the physical
development of young people. When played in modera-
tion and under suitable conditions, they are most useful
and beneficial exercises. They are played in the open air,
and demand a great variety of vigorous muscular move-
ment, with a considerable amount of skill and adroitness of
action. These games not only involve healthful exercise,
but tend to develop those manly and wholesome qualities
which are essential to success in life.

112. Physical Exercises in School. Physical exercises
of some sort should be provided for pupils in our schools,

Physical Exercise

77

especially in large towns and cities, where there is little
opportunity for outdoor games. These exercises should
form a part of the regular course of study. The object
should be the promotion of sound health rather than the
development of muscle or the per-
formance of feats of agility or strength.
Exercises with dumb-bells and wands,
or even without any apparatus, prac-
ticed a few times a day, for five minutes
at a time, do a great deal of good.
They relax the tension of body and
mind, and introduce an element of
pleasure into the routine of school
life.

113. Narcotics and Physical Exer-
cise. Recognizing the fact that alco-
holic beverages and tobacco are so
disastrous to efficiency in any system
of physical training, instructors in
physical culture rigidly forbid the use
of these narcotics under all circum-
stances. While this principle is per-
haps more rigorously enforced in
training for athletic contests, it is
insisted upon in teaching those who
have in view only the maintenance of
health.

114. Practical Points about Physi-
cal Exercise. The main object in (Based upon a photograph
undertaking systematic and graduated

physical exercises* is not to learn how to do mere feats
of strength and skill, but rather to fit one's self for the
duties and the work of life.

the Muscles may be de-
veloped on the Trapeze
or Horizontal Bar.

78 Life and Health

The most beneficial exercises ordinarily are the gentle
ones, in which no strain is put upon the heart and the
respiration. The special aim is to secure the equal use of
all the muscles, not the development of a few.

Exercises which call for sustained effort, violent exertion,
or sudden strain, are best avoided by those who have had
no preparation or training.

After the more violent exercises, as baseball, football,
a long ride on the bicycle, or even after a prolonged walk, a
bath should be taken at the first convenient opportunity.
Care should be taken to rub down thoroughly, and to
change a part or all of the clothing. It is dangerous to
stand about in clothes which are damp with perspiration.

Keep warmly clad after exercise, avoid chills, and always
stop exercising as soon as fatigue is felt. Wear clothing
which allows free play to all the muscles of the body.
The clothing should be light, loose, and made of porous
material.

In brisk walking keep the mouth shut, especially in cold
weather, and breathe through the nose, regulating the pace
so that it can be done without discomfort.

NOTE i . — Blackie's How to get Strong and how to stay so (New
and Enlarged Edition of 1898) is full of wholesome advice and prac-
tical suggestions to those who may wish to practice health exercises
at home.

NOTE 2. — One-half the struggle of physical training has been won
when a boy can be induced to take a genuine interest in his bodily
condition, — to want to remedy its defects, and to pride himself on
the purity of his skin, the firmness of his muscles, and the upright-
ness of his figure. Whether the young man chooses afterwards to
use the gymnasium, to run, to row, to play ball, or to saw wood, for
the purpose of improving his physical condition, matters little, pro-
vided he accomplishes that object. — DR. D. A. SARGENT, Director
of the Hemenway Gymnasium at Harvard University.

CHAPTER V
FOOD AND DRINK

115, The Necessity for Food. In a general way the
body may be compared to a steam engine in good working
order. An engine consumes fuel to obtain from it the
energy necessary to do its work ; so, we consume within
our bodies certain nutritious substances to obtain from them
the energy necessary for our activities. Just as the energy
for the working of the engine is obtained by the combus-
tion of fuel, so the energy expended by our bodies in the
form of muscular work or heat results from the combustion
or oxidation within us of the food we eat. Unless this
energy is provided for the body it will have but little power
of doing work, and, like an engine without steam, must
soon become motionless.

116. Waste made good by Food. A steam engine, from
the first stroke of its piston rod, begins to wear out, and
before long needs repair. All work involves waste. The
engine, unless kept in thorough repair, would soon stop.
So it is with our bodies. In their living cells chemical
changes are constantly going on ; complex substances are
being broken up into simpler combinations. It is impossible
to move a single muscle, or even to think for one moment,
without causing some substance in the muscular or brain
tissue to become of no further use in the body.

In short, so long as the body maintains its activities,
there must result a waste of substance which corresponds

79

8o Life and Health

exactly to the amount of energy expended. This continual
loss of substance must be made good by the introduction
into the body of new material. This "new material" is
the food we eat and is introduced into our bodies by means
of the alimentary canal.

The process known as digestion, by which the food thus
introduced is acted upon so that it can pass through the
delicate walls of the alimentary canal into the blood and
lymphatics, will be treated in Chapters VI and VII.

Meantime, let us learn something of the nature and
composition of food, which is so essential to the welfare of
the bodily tissues.

117. Classification of Foods. Foods may be conveniently
divided into four great classes, to which the name foodstuffs,
or alimentary principles, has been given.

I. Proteids, or Nitrogenous Foods.
II. Starches and Sugars, or Carbohydrates.

III. Fats and Oils.

IV. Inorganic or Mineral Foods, — Water, Salt.

118. Proteids, or Nitrogenous Foods. The proteids, fre-
quently spoken of as nitrogenous foods, are rich in one
or more of the following organic substances : albumin,
casein, fibrin, gelatin, myosin, gluten, and legumin.

The type of this class of foods is egg albumin, well known
as the white of an egg. The serum of the blood is very
rich in albumin, as is lean meat. The curd of milk con-
sists mainly of casein. Fibrin exists largely in blood and
flesh foods. One of the chief constituents of muscular
fiber is myosin. Gluten exists largely in the cereals, wheat,
barley, oats, and rye. The proteid principle of peas and
beans is legumin, a substance resembling casein.

Food and Drink 8 1

The principal proteid foodstuffs are milk, eggs, flesh
foods of all kinds, fish, and the cereals among vegetable
foods. Peas and beans are rich in proteids.

The essential use of the proteids, or nitrogenous food-
stuffs, to the tissues is to supply the material from which
new tissue is made or old tissue is repaired. They are also
valuable to the body as sources of energy. Now, as pro-
teids are the most important constituents of living matter,
it is evident that proteid food is the essential element of all food.
In short, if our diet contained no proteids, the tissues of the
body would gradually waste away, and death would sooner
or later result.

119. Starches and Sugars. The starches, sugars, and
gums, also known as carbohydrates, enter largely into the
composition of foods of vegetable origin. They contain
no nitrogen, but only the three elements, carbon, hydrogen,
and oxygen.

The starches are abundant in potatoes and the cereals,
and in arrowroot, sago, and tapioca.

The sugars are also widely distributed substances, and
include cane, grape, malt, maple, and milk sugars. To this
group of carbohydrates also belong the gums and the
cellulose or woody fibrous substance found in fruit, cereals,
and all vegetables. Honey and molasses are likewise
carbohydrates.

The starches and sugars are oxidized in the body, and a
certain amount of energy is thereby liberated. The energy
of muscular work and of the heat of the body comes largely
from their oxidation.

120, Fats and Oils. These include not only the ordi-
nary fats of meat, but many animal and vegetable oils. They
are rich in carbon and hydrogen, but contain little oxygen.
The principal kinds of fat used as food are the fat of meat,

82 Life and Health

butter, suet, and lard ; but in many parts of the world
various vegetable oils are largely used, as the olive, palm,
cotton seed, cocoanut, and almond.

Weight for weight the fats and oils are more valuable
than the carbohydrates as sources of energy, but the latter
are more easily digested, and more easily oxidized in the
body. An important use of fatty foods is for the main-
tenance of the bodily heat. The inhabitants of Arctic
regions are thus enabled, by large use of the fat and oil
from the animals they devour, to endure safely the severe
cold.

121. Saline or Mineral Foods. The principal mineral
foods are water, and the salts of lime, iron, magnesia,
phosphorus, sodium, and potash. Except common salt and
water, these substances are usually taken only in combina-
tion with other foods.

These saline matters are essential to health, and when
they are not present in due proportion nutrition is disturbed.
If a dog be fed on food freed from all salines, but otherwise
containing proper nutrients, he soon suffers from weak-
ness, after a time amounting to paralysis, and often dies in
convulsions.

About two hundred grains of common salt are required
daily by an adult, but a large proportion of this is con-
tained in the organic food. Phosphate and carbonate of
lime are obtained from milk and meats. Both are required
for the bones and teeth. The salts of potash, which assist
in purifying the blood, are obtained from vegetables and
fruits. An iron salt is found in most foods, and sulphur
in the yolk of eggs.

122. Water. Water is present in all foods. It is of
use chiefly as a solvent, and while not strictly a food, is
necessary to life. It enters into the construction of every

Food and Drink 83

tissue, and is constantly being removed from the body by
every channel of waste.1

As a solvent water aids digestion, and as it forms about
80 per cent of the blood, it serves as a carrier of nutrient
material to all the tissues of the body.

In brief, the presence of water in the tissues is a condition
of all vital activity.

IMPORTANT ARTICLES OF DIET

123. Milk and Eggs. The value of milk as an article of
diet cannot be overestimated. It affords nourishment in
a very simple and convenient form. It is an ideal food,
containing, in excellent proportions, all the elements neces-
sary for growth and health in earlier youth.

Eggs are often spoken of as a typical natural food. The
white of an egg is chiefly albumin, with traces of fat and
salt ; the yolk is largely fat and salts. Eggs furnish a
convenient and concentrated food, and if properly cooked
are usually readily digested.

124. Meats. The flesh of animals is one of our main
sources of food. Containing a large amount of proteid, it
is admirably adapted for building up and repairing the
tissues of the body.

Beef contains less fat and is more nutritious than either
mutton or pork. Mutton has a fine flavor and is easily
digested. Veal and pork are less easily digested. Poultry
and game are rich in phosphates.

1 The amount of water in various tissues of the body is given by the
following table in parts of 1000 :

Enamel,

•2.

Skin,

720

Blood,

791

Serum,

959

Dentine,

100

Brain,

750

Bile,

864

Gastric juice,

973

Bone,

486

Muscle,

757

Blood plasma,

901

Tears,

982

Fat,

299

Spleen,

758

Chyle,

928

Saliva,

995

Liver,

693

Kidney,

827

Lymph,

958

Sweat,

995

84 Life and Health

125. Fish. Fish forms an important and most nutri-
tious article of diet, as it contains almost as much nour-
ishment as meat. The fish-eating races and classes are
remarkably strong and healthy. As a rule, shellfish, except
oysters, are not very digestible. Some persons are unable
to eat certain kinds of fish, especially shellfish, without
producing eruptions on the skin and other symptoms of
mild poisoning.

126. Vegetable Foods. This is a large and important
group of foods, and embraces a remarkable number of dif-
ferent kinds of diet. Vegetable foods include the cereals,
garden vegetables, the fruits, and other less important
articles. These foods supply a certain quantity of proteid
and fat, but their chief use is to furnish starches, sugars,
acids, and salts.

The vegetable foods, especially the cereals, indirectly supply
the body with water, a great deal of which is absorbed by
them in the process of cooking.

127. Proteid Vegetable Foods. The most important pro-
teid vegetable foods are those derived from the grains of
cereals and certain leguminous seeds, as peas and beans.
The grains when ground make the various flours or meals.
They contain a large quantity of starch, a proteid sub-
stance peculiar to them called gluten, and mineral salts,
especially phosphate of lime. Wheat, oatmeal, and corn
are most important articles of diet. Wheat flour contains
starch, sugar, and gluten — nearly everything to support
life except fat, in which it is very poor. Oatmeal is rich in
proteids.

Corn meal is not only rich in proteid, but also in fat ;
hence it is a most important and nutritious article of food.
Rice, on the other hand, contains less proteid than any
other cereal grain, and is the least nutritious. Peas and

Food and Drink 85

beans, distinguished from all other vegetables by their large
amount of proteids, excel in this respect even beef, mutton,
and fish. They take the place of meats with those who
believe in a vegetable diet. fc

128. Non-Proteid Vegetable Foods. The common potato
is the best type of non-proteid vegetable food. When properly
cooked it is easily digested and makes an excellent article of
diet. It is unfit for an exclusive food, but is best used with
milk, meat, and other foods richer in proteid substances.
Sweet potatoes, of late years extensively used as food, are
rich in starch and sugar. Arrowroot, sago, tapioca, and
similar foods are nutritious, and easily digested.

129. Non-Proteid Animal Foods. Butter is one of the
most digestible of animal fats, wholesome, agreeable, and
delicate in flavor, and is on this account much used as
a food. Various substitutes have of late years come into
use. These are made from animal fat, chiefly that of
beef, and are known as butterine, oleomargarine, and by
other trade names. These preparations, if properly made,
are wholesome, and may be useful substitutes for butter.

130. Garden Vegetables. Various green, fresh, and suc-
culent vegetables, such as celery, cabbages, beets, lettuce, and
turnips, form an important part of our diet. They are of
use not so much on account of their proteids, carbohy-
drates, or fats, which are usually small in quantity, as for
the salts they supply, especially the salts of potash. The
long-continued use of a diet without fresh vegetables often
leads to a disease known as scurvy.

Vegetables are also used for the agreeable flavor pos-
sessed by many, and the pleasant variety and relish they
give to the food. The undigested residue left by all
green vegetables affords a useful stimulus to intestinal
contraction.

86 Life and Health

Explanation of the Graphic Chart. The graphic chart, on the
opposite page, presents in a succinct and easily understood form
the composition of food materials as they are bought in the market,
including the edible and non-edible portions.

This chart has be^n rearranged and compiled from a monograph
on " Foods and Diet " which may be found in the Yearbook of the
United States Department of Agriculture for 1894.

KEY : I, percentage of nutrients ; 2, fuel value of i pound in calories. The unit of
heat, called a calorie, or gramme-degree, is the amount of heat which is necessary
to raise one gramme (1543 grains) of water one degree Centigrade (1.8° Fahr.).
A, round beef ; £, sirloin beef ; C, rib beef ; £>, leg of mutton ; E, sparerib
of pork ; F, salt pork ; G, smoked ham ; //, fresh codfish ; 7, oysters ; /, milk ;
K, butter ; L, cheese ; M, eggs ; N, wheat bread ; O, corn meal ; P, oatmeal ;
Q, dried beans ; /?, rice ; S, potatoes ; T, sugar.

This table, among other things, shows that the flesh of fish contains
more water than that of warm-blooded animals. It may also be seen
that animal foods contain the most water, and vegetable foods,
except potatoes, the most nutrients. Proteids and fats exist only in
small proportions in most vegetables, except beans and oatmeal.
Vegetable foods are rich in carbohydrates, while meats contain none.
The fatter the meat the less the amount of water. Thus, very lean
meat may be almost four-fifths water, and fat pork only one-tenth
water.

131. Fruits. Fruits — as oranges, strawberries, apples,
grapes, and bananas — are a useful addition to our regular
diet. They are cooling and refreshing, of agreeable flavor,
and tend to prevent constipation. Their flavor and juici-
ness serve to stimulate a weak appetite and to give variety
to the diet. If eaten in an unripe or an overripe state, fruits
may occasion a disturbance of the ^stomach and bowels.

132. Condiments. The refinements of cookery, as well
as the craving of the appetite, demand many articles which
cannot be "classed strictly as foods. They are called con-
diments, and as such may be used in moderation. They
give flavor and relish to food, excite appetite, and promote
digestion.

Food and Drink

COMPOSITION OF FOOD MATERIALS

Nutritive ingredients, refuse, and fuel value

Nutrients.

Non-Nutrients.

Protein. Fats. Carbo- Mineral

hydrates, matters.

Water. Refuse.

FIG. 44. Graphic Chart of the Composition of Food Materials.

88 Life and Health

The more common condiments are salt, vinegar, pepper,
ginger, nutmeg, cloves, and various substances containing
ethereal oils and aromatics. Their excessive use is likely
to cause disorder of the digestive organs.

133. Salt. The most important and extensively used of
the condiments is common salt. It exists in all ordinary
articles of diet, but in quantities not sufficient to meet the
wants of the bodily tissues. Hence it is added to most
articles of food. It improves their flavor, promotes certain
digestive secretions, and meets the nutritive demands of
the body. The use of salt seems based upon an instinc-
tive demand of the system. Food without salt, however
nutritious in other respects, is taken with reluctance and
digested with difficulty.

134. Water. The most important natural beverage is pure
water ; in fact, it is the only one required. It is a large ele-
ment of solid foods. As we have already learned, the bodily
tissues are made up to a great extent of water. Everything
taken into the circulating fluids of the body, or eliminated
from them, is done through the agency of water. As a
solvent it is indispensable in all the activities of the body.

It has been estimated that an average-sized adult loses
by means of the lungs, skin, and kidneys about eighty
ounces of water every twenty-four hours. To make up
for this loss about four pints of water must be taken daily.
About one pint of this is obtained from the food we eat,
the remaining three pints being taken as drink. One of
the best ways of supplying water to the body is by drink-
ing it in its pure state, when its solvent properties can be
completely utilized.

135. Need of Pure Water. As water is one of the essen-
tial constituents of the body, it is highly important that it
should be free from harmful impurities. If it contain the

Food and Drink 89

germs of disease, sickness may follow its use. Without
doubt the most important factor in the spread of disease
is, with the exception of impure air, impure water. It is the
chief agent in the spread of typhoid fever. The evidence
is likewise overwhelming that filthy water is an all-powerful
agent in the spread of that terrible disease cholera.

136. Tea and Coffee. It has been estimated that one-
half of the human race now use tea, either habitually or
occasionally. Its immoderate use is a prolific source of
indigestion, palpitation of the heart, persistent wakeful-
ness, and of other disorders. Persons who cannot use it
without feeling its hurtful effects should leave it alone. It
should not.be taken on an empty stomach, nor sipped after ^
every mouthful of food.

Coffee often disturbs the rhythm of the heart and causes
palpitation. Taken at night it often causes wakefulness.
This effect is so well known that it is often employed to
prevent sleep. Immoderate use of strong coffee may pro-
duce other harmful effects, such as muscular tremors, sick
headache, palpitation, and various uncomfortable feelings
in the cardiac region. Some persons cannot drink even a
small amount of tea or coffee without these unpleasant
effects. These beverages are unsuitable for young people.

137. Cooking. The art of cooking plays a very important
part in the matter of health, and thus of comfort and hap-
piness. Badly cooked and ill-assorted foods are often the
cause of serious digestive disorders. Mere cooking is not
enough, but good cooking is essential. Cooking enables
food to be more readily chewed and more easily digested.
Thus, a piece of meat when raw is tough and tenacious,
but if cooked it loses much of its toughness, because the
connective tissues are changed into a soft and jelly-like
mass. Besides, the meat is more readily acted upon by the

90 Life and Health

digestive fluids. Cooking also makes vegetables and cereals
softer and enables the digestive juices readily to penetrate
their substance.

Cooking improves or develops flavors in food (especially
in animal foods), which tend to stimulate the appetite and
the flow of digestive fluids.

Another important use of cooking is that it kills any
minute parasites or germs in the raw food. The safeguard
of cooking thus effectually removes some important causes
of disease.

ALCOHOL AND ALCOHOLIC BEVERAGES

138, Alcoholic Beverages. There is a class of liquids so
commonly and so widely used as beverages, and their effect
upon the physical life is so far-reaching, so characteristic,
and so dangerous, that their consideration demands special
treatment in this chapter. -We refer to alcoholic beverages,
which on account of their great variety, their remark-
able and widespread use, and their subtle and deleterious
effects upon the bodily life, should enlist our earnest
attention.

139. Properties of Alcohol. Alcohol is formed out of
sugar by the process of fermentation. Sugar and alcohol,
and many other substances of widely different natures, are
built up of the same elements (carbon, hydrogen, and
oxygen), but in varying proportions. For example, common
or ethyl alcohol differs in chemical composition from fusel oil,
one of the most poisonous of the alcohol series, only in the
proportion of the same elements. Fermentation changes
the combination of the elements composing sugar in such
a way as to produce two very different compounds, alcohol
and carbon dioxide.

Food and Drink 9 1

140. Nature of Fermentation. The ceaseless action of
minute forms of plant life in bringing about the decom-
position of the elaborated products of organized animal or
vegetable structures is described in Chapter XIII.

All such work of vegetable organisms, whether going
on in moulding cheese, in souring milk, in putrefying meat,
in rotting fruit, or in decomposing fruit juice, is essentially
one of fermentation. There are many kinds of fermentation,
each produced by some special form of minute plant or
micro-organism.

141. Alcoholic Fermentation. Let us now briefly turn
our attention to that fermentation which results from
the decomposition of sweet fruit, or other vegetable juices,
which are composed largely of water, containing sugar and
flavoring matters.

This special form of fermentation is known as alcoholic
or vinous fermentation, and the minute germs, or micro-
organisms, that cause it are familiarly termed "alcoholic
ferments." There are several varieties of these germs,
classed by scientists as saccharomycetes, which are found
on the surfaces and stems of fruit as it is ripening.

While the juice is in the fruit the conditions are less
favorable for the work of the alcoholic ferments than for
that of moulds.1 Hence fruit rots as a result of the work
of moulds, which, growing within and upon it, cause its
decomposition.

1 The work of some kinds of moulds may be apparent to the eye, as in
the growths that form on old leather and stale bread and cheese. That of
others goes on unseen, as when acids are formed in stewed fruits. Con-
cerning the work of the different kinds of moulds, Troussart says : " Mucor
mucedo devours our preserves ; Ascophora mucedo turns our bread mouldy ;
Molinia is nourished at the expense of our fruits ; and Chatomium chartatum
develops itself in books and on their bindings, when they come in contact
with a damp wall." — TROUSSART'S Microbes, Ferments, and Moulds.

92 Life and Health

But when fruit is crushed and its juice pressed out, the
minute germs, or micro-organisms, are carried into it, where
they absorb the sugar, which is for them as well as for man
a source of energy. By so doing they cause a breaking up
of the sugar and a rearrangement of its atoms.

Two new substances result from this decomposition of
sugar ; viz., carbon dioxide, which escapes as bubbles of gas
into the surrounding air, and alcohol, which remains in the
fluid. Now we must remember that fermentation entirely
changes the nature of the substance fermented. This law holds
good for all forms of decomposition. Before alcoholic fer-
mentation the fruit juice was wholesome and beneficial ;
after fermentation it contains a liquid commonly known as
alcohol, which changes the previously wholesome fruit juice
into an intoxicating beverage.

Experiment 29. To illustrate yeast fermentation. Dissolve one-
fourth of a compressed yeast cake in half a cup of warm water ; stir
well. Now add two tablespoonfuls of molasses to a pint of warm
water. Pour the first mixture into the second and shake well. Place
mixture in a wide-mouthed, loosely stoppered quart bottle or quart
glass. Note color of the mixture, its taste and smell.

Place the mixture on shelf near the kitchen fire or in any place
where temperature is from 70° to 95° Fahr. After several hours, watch
for evidence that the yeast is "working." Note the bubbles rising
through the liquid, due to the splitting up of the sugar into car-
bon dioxide and alcohol. The alcohol formed by the yeast can be
separated by distillation.

Experiment 30. After the mixture is " working," shake and pour *
a little into a bottle and place it in the ice chest or in ice water for an
hour. Note the effect on the "working."

142. The more Common Fermented Beverages. Taking
advantage of the great law of fermentation which dominates
the realm of nature, man has devised means to manufacture
various alcoholic beverages from a great variety of vegetable

Food and Drink 93

substances, as ripe grapes, pears, apples, and other fruits,
cane juices, corn, the malt of barley, rye, wheat, and other
cereals.

The process differs according to the substance used and
the manner in which it is treated, but the ultimate outcome is
always the same, viz., the production of a beverage contain-
ing a greater or less proportion of alcohol.

The more common alcoholic beverages produced by
vinous fermentation are beer, wine, and cider.

The use of these drinks costs the world every year thou-
sands of valuable lives and an inestimable loss of physical
and mental working ability, besides a vast amount of crime
and immorality. It is the nature of the alcohol which these
drinks contain to create an increasing appetite for more
alcohol, and to weaken the self-control necessary for resist-
ing the appetite.

143. Distilled Liquors. When any kind of fermented
liquor is heated, the vapor which first comes off contains
much of the alcohol. Now if this alcoholic vapor be col-
lected and cooled it takes the form of a much stronger
liquid alcohol.

This process is known as distillation, and the product is
called distilled liquor.

The more common distilled liquors are brandy, rum,
whisky, and gin ; they are more harmful and dangerous than
beer, wine, and cider, because they contain more alcohol.

144. The Effects of Small Quantities of Alcohol. Careful
experiments show that the greater part of the alcohol of ordi-
nary beverages, when used in small or moderate quantities,
is burnt up or oxidized within the body. A small per cent
of this alcohol may, however, be excreted unchanged in
the breath and from the kidneys. Observations show that
alcohol thus oxidized yields a certain amount of heat energy,

94 Life and Health

as the oxidation of starch and sugar in the body yields
v energy ; but the result to the body is quite different from
that of the oxidation of foods. The energy yielded by
foods makes the body warmer, while that gained from
alcohol may be more than counterbalanced by the greater
loss of heat resulting from the dilatation of the cutaneous
blood vessels from the effect of the alcohol upon the nerves
in the skin.

In brief, the oxidation of ordinary food makes the
body better able to work and keep warm ; the oxidation
of alcohol makes the body less able -to work and keep
warm. Repeated test experiments have shown that alcohol
decreases the amount of muscular work and lowers the
quality of mental work done within the period of its influ-
ence. Its action is, therefore, antagonistic to the true
purpose of food, while it is in harmony with the action
of poisons.

145. Alcohol not a Food. Because alcohol in small quan-
tities is oxidized within the body and supplies energy, it by
no means follows that it is a food in the ordinarily accepted
sense in which the word "food" is used. Under these
conditions many harmful substances, as ether, chloroform,
and morphine, would be classed as foods, for they are
oxidized within the body and furnish a certain amount of
energy. From a purely scientific and technical point of
view alcohol may, therefore, liberate its energy within the
body ; but as this is at the expense of other essential
requirements of a food, there are clearly no logical grounds
for calling it a food in the ordinary and accepted meaning of
i the term. An actor is not a king because for a brief hour he
walks the stage in royal dress and speaks majestic words.

Definitions of the word "food " are not always expressed
in the same terms, but all definitions substantially accepted

Food and Drink 95

by the scientific world assume that a food, when properly
taken, serves to build up and repair the body and to supply
it with energy for its warmth and work, without injury to
the tissues,

Until it is proved that the sum total of the effect of
ingested alcohol is useful rather than harmful to the main-
tenance of the animal economy, it seems more logical,
certainly less misleading, to accept -the classification of
standard authorities and class alcohol as a powerful drug,
— a narcotic poison rather than a food.

In fact, when we stop to think of the possibilities
involved in the ingestion of even a very small quantity
of alcohol, the idea of calling it a food appears like a con-
tradiction of terms.

146. Alcohol as a Poison. Alcohol, the product of vinous
fermentation, the deleterious element, the "toxin," of minute
germs known as the saccharomycetes, is a poison. The chief
toxic element in all kinds of alcoholic liquors is ethylic or
ordinary alcohol, although amylic alcohol, or "fusel oil,"
is found in raw whisky.

Ethylic alcohol is a distinct substance of definite chem-
ical composition and affinities, and as a poison is second to
none in its subtle and profound effect upon the bodily
tissues. The chemical nature of ethylic alcohol cannot be
lost in the smallest quantity, but must in every qualitative
analysis remain the same, so long as by progressive division
its substance as such still exists, even down to the last
molecule.

In brief, let us then remember that alcohol acts as a true
poison, whether we breathe in its vapor, swallow the liquid
in dilute form, or have it injected into the cellular tissue
by means of a hypodermic needle. It does not alter the
inherent poisonous property of alcohol because when taken

96 Life and Health

in small quantities or in dilute forms its deleterious effects
upon the bodily life may not for a time be obvious.1 Arsenic
and lead are no less poisons because it may take many
days before their toxic effects upon the tissues are clearly
exhibited.

ADDITIONAL EXPERIMENTS

Experiment 31. As a type of the group of proteids we take the
white of egg, — egg-white or egg albumin. Break an egg carefully, so
as not to mix the white with the yolk. Drop about half a teaspoon-
ful of the raw white of egg into half a pint of distilled water. Beat
the mixture vigorously with a glass rod until it froths freely. Filter
through several folds of muslin until a fairly clear solution is obtained.

Experiment 32. To a small quantity of this solution in a test tube
add strong nitric acid, and boil. Note the formation of a white pre-
cipitate, which turns yellow. After cooling, add ammonia, and note
that the precipitate becomes orange.

Experiment 33. Add to the solution of egg albumin excess of
strong solution of caustic soda (or potash), and then a drop or two
of very dilute solution (i per cent) of copper sulphate. A violet
color is obtained, which deepens on boiling.

Experiment 34. Boil a small portion of the albumin solution in a
test tube, adding drop by drop dilute acetic acid (2 per cent) until
a flaky coagulum of insoluble albumin separates.

1 Alcohol is a poison. So is strychnine ; so is arsenic ; so is opium. It
ranks with these agents. Health is always in some way or other injured
by it; benefited by it — never. — SIR ANDREW CLARK, M.D., one of the
most eminent physicians of our day.

Alcohol, even when diluted, as in wine, beer, and cider, is a poison which
changes pathologically the tissues of the body and leads to fatty degenera-
tion.— DR. AUGUST FOREL, formerly Professor of Psychiatry in the
University of Zurich.

A very large number of people are dying day by day, poisoned by
alcohol, but not supposed to be poisoned by it. — SIR WILLIAM GULL,
M.D., F.R.S., Consulting Physician to Guy's Hospital, London.

Food and Drink 97

Experiment 35. Moisten some flour with water until it forms a
tough, tenacious dough ; tie it in a piece of cotton cloth, and knead
it in a vessel containing water until all the starch is separated. There
remains on the cloth a grayish white, sticky, elastic "gluten," made
up of albumin, some of the ash, and fats. Draw out some of the
gluten into threads and observe its tenacious character.

Experiment 36. Use fresh cow's milk. Examine the naked-eye
character of the milk. Test its reaction with litmus paper. It is
usually neutral or slightly alkaline.

Experiment 37. Examine with the microscope a drop of milk, not-
ing numerous small, highly refractive oil globules floating in a fluid.

Experiment 38. Take one or two teaspoonf uls of fresh milk in a test
tube ; heat it until it is lukewarm, and add a small quantity of liquid
rennet. Note that the whole mass curdles in a few minutes, so that
the tube can be inverted without the curd falling out. Soon the curd
shrinks and squeezes out a clear, slightly yellowish fluid, the whey.

Experiment 39. Place some Fehling's solution (which can be
obtained readily at the drug store, or tablets may be bought which
answer the same purpose) in a test tube, and boil. If no yellow
discoloration takes place, it is in good condition. Add a few drops
of grape or milk sugar solution and boil, when the mixture suddenly
turns to an opaque yellow or red color.

Experiment 40. Mix an even teaspoonful of wheat flour, Indian
meal, oatmeal, or rye meal with an equal volume of ether.1 Stir
carefully and filter mixture after it has stood for fifteen minutes to
get rid of the ether odor. Evaporate some of the filtrate on a watch
glass. A greasy residue is left, which may be shown by rubbing it
on a piece of tissue or rice paper.

1 Benzine may be used instead of ether, as it is much cheaper and more
readily obtained. As its vapor, as well as that of ether, is highly inflam-
mable, the greatest caution must be exercised not to handle it near a flame
or a hot stove.

CHAPTER VI
THE DIGESTION OF FOOD

/ 147. How Waste is made good by Food. As we have
learned in a previous chapter, our bodies are subject to
continual waste, which occurs in no one part alone, but in
all the tissues.

Now the liquid part of the blood comes into direct
contact with every one of these tissues, the ultimate cells
of which are constantly being bathed by this nutritive fluid,
which brings to them the material needed for their renewal.
These cells are able to select from the fluid of the blood
whatever they require to repair their waste and to provide
for their renewed activity.

To keep the blood from becoming impoverished the
materials which it is constantly losing must be supplied
from some source outside of the body. This necessitates
the ingest ion of articles which are known as food.

The most important and complicated process by which
food is made ready to pass into the blood is known as
digestion, and the organs concerned in bringing about this
marvelous change in the food are the digestive organs.
f 148, The Digestive Organs in General. The digestive
apparatus of the human body consists of the alimentary
canal and tributary organs which, although outside of this
canal, communicate with it by ducts.

The alimentary canal consists of the mouth, the pharynx,
the oesophagus, the stomach, and the intestines.

98

The Digestion of Food 99

Other digestive organs which are tributary to this canal,
and discharge their secretions into it, are the salivary glands,1
the liver, and the pancreas.

The digestive process may be subdivided into three steps,
which take place respectively in the mouth, in the stomach,
and in the intestines.

X149. The Mouth. The mouth is the cavity formed by
the lips, the cheeks, the palate, and the tongue. Its bony
roof is made up of the upper jawbone on each side in front,
and of the palate bones behind. This is the hard palate.

The mouth continues behind into the throat, the separa-
tion between the two being marked by fleshy pillars which
arch up from the sides to form the soft palate. In the
middle of this arch there hangs from its free -edge a little
lobe called the uvula (Figs. 45 and 51).

On each side where the pillars begin to arch is an
almond-shaped body known as the tonsil. When we take
cold one or both of the tonsils may become inflamed, and
so swollen as to obstruct the passage into the throat.
xl50. Mastication, or Chewing. The first step in the
process of digestion is chewing, or mastication, the cutting
and grinding of the food by the teeth. While the food is

1 Glands. Glands are organs of various shapes and sizes, whose special
work it is to separate materials from the blood for further use in the body,
the processes being known as secretion and excretion. The means by which
secretion and excretion are effected are, however, identical.

The essential parts of a gland" are a basement membrane, on one side of
which are found the secreting cells, on the other the blood current, flowing
in exceedingly thin-walled vessels known as the capillaries. The cells are
able to select from the blood whatever material they require, which they
elaborate into their particular secretion.

In Fig. 47 is illustrated, diagrammatically, the structure of a few typical
secreting glands. The continuous line represents the basement membrane.
The dotted line represents the position of the cells on one side of the base-
ment membrane. The irregular lines show the position of the blood vessels.

IOO

Life and Health

thus being crushed it is moved to and fro by the varied

movements of the tongue, so that every part of it may be

mixed with saliva.

151. The Teeth. The teeth are attached to the upper and

lower maxillary bones by roots contained in sockets in the

jaws. Each tooth
consists of a
crown, the visible
part, and one or
more fangs, buried
in the sockets.
There are in
adults thirty-two
teeth, sixteen in
each jaw.

Teeth differ in
name according
to their form and
the uses to which
they are specially
adapted. Thus, at
the front of the
jaws there are
incisors, or 'cutting
teeth, two on each
side. The incisors

FiG. 45. Cavities of the Mouth, Pharynx, etc.
(Section in the middle line designed to show the mouth

in its relations to the nasal fossae, the pharynx, and

the larynx.)
A, sphenoidal sinus ; £, internal orifice of Eustachian

tube; C, velum palati; D, anterior pillar of soft

palate ; £, posterior pillar of soft palate ; F, tonsil ;

//, lingual portion of the pharynx ; K, lower portion

of the pharynx; L, larynx; Af, section of- hyoid

bone ; N, epiglottis ; O, palatine arch.

divide the food
and are well devel-
oped in rodents, as squirrels, rats, and beavers.

Next come the canines, or cuspids, two in each jaw,
so called from their resemblance to the teeth of dogs and
other flesh-eating animals. The upper two are often called
eye teeth, and the lower two, stomach teeth.

The Digestion of Food

Next behind the* canines follow, on each side, two
bicuspids. The three hindmost teeth in each jaw are the
molars, or grinders. The last molars are known as the
"wisdom teeth" (Figs. 46 and 51).

X152. Development of the Teeth. The teeth just described
are the "second," or permanent set, which succeeds the tem-
porary, or milk teeth. The latter are twenty in number, five
on each side of each jaw, that is, two incisors, one canine,

FIG. 46. Temporary and Permanent Teeth together.

Temporary teeth : A, central incisors ; B, lateral incisors ; C, canines ; £>, anterior
molars ; E, posterior molars. Permanent teeth : F, central incisors ; ff, lateral
incisors ; K, canines ; £, first bicuspids ; M, second bicuspids ; N, first molars.

and two molars. The milk teeth appear during the first and
second years, and last until about the sixth or seventh year,
from which time until the twelfth or thirteenth year they are
gradually pushed out, one by one, by the permanent teeth.
The roots of the milk teeth are muchr.smaller than those of
the second set.

153, Structure of the Teeth. If we should saw a tooth
down through its center we should find in the interior

i o 2 Life and He a Ilk

a cavity. This is the pulp cavity, which is filled with the
dental pulp, consisting chiefly of nerves and blood vessels.
Irritation of this delicate pulp, due to the decay of the
dentine, gives rise to toothache (Fig. 48).

Surrounding the cavity on all sides is the hard substance
known as the dentine, or ivory. Outside the dentine of
the root is a substance closely resembling bone, called
cement. The root is held in its socket by fibrous membrane
which surrounds the cement as the periosteum does bone.

The crown of the tooth is not covered by cement, but
by the hard enamel, which forms a strong protection for
the exposed part.

FIG. 47. Diagram of the Structure of
Secreting Glands.

A, simple tubular gland ; B, gland with mouth shut and sac formed ; C, gland

with a coiled tube ; £>, plan of part of a racemose gland.
f

^ 154. The Salivary Glands. While the food is being
chewed it is moistened with a fluid called saliva, which flows
from six little glands, three on each side of the mouth. The
parotid is situated in front of the ear. In the disease known
as "mumps," common in childhood, this gland becomes
inflamed and swollen. The submaxillary gland is placed on
the inner side of the lower jaw ; the sublingual is on the floor
of the mouth, between the tongue and the gums. Each
gland opens into the^nouth by a little duct (Fig. 49).
1 155. The Saliva. The saliva is a colorless liquid with-
out taste or smell. Its principal constituent, besides water,
is a ferment called ptyalin, which has the remarkable

The Digestion of Food 103

property of being able to change starch into a form of
cane sugar known as maltose.

Thus, while the food is being chewed, another process
is going on by which starch is changed into sugar. The
saliva moistens the food, thus fitting it for swallowing, and
it also aids in speech by keeping the mouth moist.

The activity of the salivary glands is largely regulated
by their abundant supply of nerves. Thus, the saliva may
flow into the mouth, even at the sight, smell, or thought
of food. This is popularly known as " making the mouth
water." The flow of saliva may be checked by nervous
influences, as sudden terror and undue anxiety.

Experiment 41. To show the action of saliva on starch. Saliva
for experiment may be obtained by chewing a piece of India rubber
and collecting the saliva in a test tube. Observe that it is colorless
and either transparent or translucent, and when poured from one
vessel to another is glairy and more or less adhesive. Its reaction is
usually alkaline to litmus paper.

Experiment 42. Make a thin paste from pure starch or arrowroot
and boil it for a minute. Dilute a little of the saliva with five volumes
of water. Label three test tubes A, B, and C. In A, place starch
paste ; in B, saliva ; and in C, one volume of saliva and three volumes
of starch paste. Place them for ten minutes in a water bath at about
104° Fahr., or in any place where the temperature is about that of
the body.

Test portions of all three for sugar, by means of Fehling's solution
or tablets.1 A and B give no evidence of sugar. C gives a yellow or
red deposit of cuprous oxide, thereby proving that starch is thus con-
verted into sugar by the saliva. This is done by the ferment ptyalin
contained in saliva.

1 Tablets and other material for Fehling's test and additional tests for
sugar can be purchased or ordered at any drug store.

The practical details of these, and other tests which assume some knowl-
edge of chemistry, may be taught orally by the teacher or learned from
some manual on the subject.

Life and Health

— A

' 156. The Pharynx. The pharynx forms a sac, into
which the mouth opens. Just above the mouth are the
two posterior passages into the nose. There are also little
openings, one on each side, from which
begin the Eustachian tubes, which lead
upward to the cavities in the interior
of the ear.

The windpipe opens downward from
the pharynx, but this communication
can be shut off by a little plate or
lid of cartilage, the epiglottis. During
the act of swallowing this closes down
over the entrance to the windpipe, and
the windpipe rises up to meet the lid.
This prevents the food from passing
into the air passages (Figs. 45 and 5 i).

Experiment 43. Open the mouth wide ;
press down the back of the tongue gently
with the handle of a teaspoon. With the
aid of strong sunlight and a hand mirror the
epiglottis may be seen.

< 157. The (Esophagus. The oesopha-
gus, or gullet, is a tube about nine
inches long, reaching from the throat
to the stomach. It lies behind the windpipe, pierces the
diaphragm, which is between the chest and the abdomen,
and opens into the stomach. It has in its walls muscular
fibers, which, by their wave-like contractions, grasp the
successive masses of food as they pass downwards and
force them into the stomach.

158. Deglutition, or Swallowing. The food, having been
well chewed and mixed with saliva, is now a soft, pasty
mass, ready to be swallowed. The tongue gathers it up and

— B

— c

- D

FIG. 48. Longitudinal
Section of a Tooth.

A, enamel ; B, pulp cavity ;
C, dentine ; £>, cement.

The Digestion of Food

105

forces it backwards between the pillars of the fauces into
the pharynx. There is only one pathway for the food to
travel, and that is down the oesophagus.

The slow descent of the food may be seen if a horse or
dog be watched while swallowing. Even liquids do not fall
or flow down the food passage. Hence it is that acrobats
are able to drink while standing on their heads, and that
a horse drinks with his mouth below the level of the
stomach. The food is under the control of the will until
it has entered the pharynx ; all the
later movements are involuntary.

Experiment 44. Place the fingers on
the " Adam's apple." Pretend to swallow
something, and you can feel the upper
part of the windpipe and get a very fair
idea of the action of the epiglottis and the
closing of its lid, thus covering the entrance
and preventing the passage of food into the
windpipe.

159. The Stomach. The stomach

is the most dilated portion of the FIG. 49. Section of Face,
alimentary canal and-ihc piiucipal (Showing the parotid and

c , . . T r submaxillary glands.)

organ o£ -digest-ton. Its form is not

easily described. It has been compared to a bagpipe,
which it resembles somewhat when moderately distended
(Fig. 52).

We may describe the stomach as a pear-shaped bag, with
a capacity of about four pints. It lies chiefly on the left
side of the abdomen, under the diaphragm, and protected
by the lower ribs.

The orifice by which the food enters the stomach is called
the cardiac opening, because it is near the heart. The open-
ing by which the food leaves the stomach and where the

io6

Life and Health

FIG. 50. Showing the Principal Organs of the Thorax and

Abdomen in situ.
(The principal muscles are seen on the left, and superficial veins on the right.)

The Digestion of Food

107

intes

intestine begins is known as \hzpyloric orifice. It is guarded
by a kind of valve, known as the pylorus, or gatekeeper.

160. Coats of Stomach. The walls of the stomach are
formed of four coats, known successively from without as
serous, muscular, submucous,

and mucous. The outer coat
is the serous membrane
which lines the abdomen, —
the peritoneum (sec. 167).
The second coat is muscular,
having three sets of involun-
tary muscular fibers. The
third coat (submucous) is
made up of loose connective
tissue. Lastly, the mucous
coat, a moist, pink, inelastic
membrane, completely lines
the stomach. When the
stomach is not distended the
mucous layer is thrown into
folds presenting a corrugated
appearance.

161. The Gastric Glands.
If we were to examine with
a hand lens the inner sur-
face of the stomach, we
should find it covered with

little pits, or depressions.

FIG. 51. A View into the Back Part
of the Adult Mouth.

These" are the Openings Of <Th* head is represented as having been

thrown back, and the tongue drawn for-

the gastric glands (Fig. 53). ward.)

Soon after food enters A> #> incisors ; C, canine; D, ^bicuspids;

F, //, PC, molars ; M, anterior pillar of the
fauces ; N, tonsil ; L, uvula ; O, upper
part of the pharynx ; P, tongue drawn
forward ; J?, linear ridge, or raphe.

the stomach, drops of fluid,
known as gastric juice, col-
lect at the mouths of these
glands and trickle down its walls to mix with the food
and to aid in its digestion.

1 08 Life and Health

162. Digestion in the Stomach. When the food, thor-
oughly mixed with saliva, has entered the stomach, the
cardiac end of that organ is closed, as well as the pyloric
valve, and the muscular walls contract on the contents. A
spiral wave of motion begins, becoming more rapid as diges-
tion goes on. The food is thus constantly churned about in
the stomach and thoroughly mixed with the gastric juice.

163. The Action of the Gastric Juice. The gastric juice is
a thin, almost colorless fluid, with a sour taste and odor.

B

D

FIG. 52. The Stomach.
A, cardiac end ; B, pyloric end ; C, lesser curvature ; D, greater curvature.

Its reaction is distinctly acid. Its chief constituents are
two ferments called pepsin and rennin, free hydrochloric
acid, mineral salts, and 95 per cent of water.

Pepsin, the most important constituent of the gastric
juice, has the power of dissolving the proteid foodstuffs,
converting some into what are called peptones, which are
both soluble and capable of filtering through membranes.

Pepsin can do this only in the presence of an acid. Hence
the importance of the hydrochloric acid of the gastric juice.

The Digestion of Food

109

The gastric juice has no action on starchy foods, neither
does it act on fats, except to dissolve the albuminous walls
of the fat cells. The fat itself is thus set free in the form
of minute globules.

/ 164, Passage of the Food into the Intestines. The con-
tents of the stomach now assume the appearance and
the consistency of a thick soup,
usually of a grayish color, known
as chyme.

After a variable time, from
one to four hours, the chyme
begins to move on in succes-
sive portions into the next part
of the alimentary canal. The
ring-like muscles of the pylorus
relax at intervals to allow the
muscles of the stomach to force
the partly digested mass into the
small intestines. This action is
frequently repeated, until even
the indigestible masses which the gastric juice cannot break
down are crowded out of the stomach into the intestines.
From three to four hours after a meal the stomach is again
quite emptied. ^SL

A certain' amount of this semiliquid mass, especially
the peptones, is at once absorbed, making its way through
the delicate vessels of the stomach into the blood current.
* 165. The Small Intestine. At the pyloric end of the
stomach the alimentary canal becomes again a slender
tube, about twenty feet long, called the small intestine. It is
divided, for convenience of description, into three parts.

The first part is called the duodenum, because it is about
twelve fingers' breadth long, that is, about eight inches.

FIG. 53. Pits in the Mucous
Membrane of the Stomach,
and Openings of the Gastric
Glands.
(Magnified 20 diameters.)

I IO

Life and Health

Into this portion opens the bile duct from the liver and the
duct from the pancreas, which first unite and then enter
the intestine as a common duct.

The next portion of the intestine
is called the jejunum, because it is
usually empty after death.

The remaining portion, known
as the ileum, terminates in the
right iliac region, and opens into
the large intestine. This opening
is guarded by the ileo-caecal valve, a
kind of movable partition provided
with a button-hole slit. This valve
permits the passage of material from
the small to the large intestine, but
prevents its backward movement.

Experiment 45. To show that pepsin
and acid are necessary for gastric diges-
tion. Take three beakers, or large test
tubes ; label them A, B, C. Put into A
water and a few grains of powdered
pepsin. Fill B two-thirds full of dilute
hydrochloric acid (one teaspoonful to a
pint), and fill C two-thirds full of dilute
hydrochloric acid and a few grains of
pepsin. Put into each a small quantity
of well-washed fibrin, and place them all
in a water bath at 104° Fahr. for half
an hour, or in any other warm place.

Examine them. In A, the fibrin is
unchanged ; in B, the fibrin is clear and
swollen up ; in C, it has disappeared,
having first become swollen and clear,
being finally converted into peptones.

FIG. 54.

(A highly magnified view of a
peptic or gastric gland, which
is represented as giving off
branches. It shows the co-
lumnar epithelium of the sur-
face dipping down into the
duct D of the gland, from
which two tubes branch off.
Each tube is lined with co-
lumnar epithelial cells, and
there is a minute central pas-
sage with the " neck " at N.
Here and there are seen other
special cells, called parietal
cells, P, which are supposed
to produce the acid of the
gastric juice. The principal
cells are represented at C.)

and completely dissolved,

Therefore, both acid and ferment are required for gastric digestion.

The Digestion of Food

1 1 1

166. The Coats of the Small Intestine. Like the stomach,
the small intestine has four coats, the serous, muscular, sub-
mucous, and mucous. The serous is the peritoneum. By the
contraction of the muscular coat the food is forced along
the bowel. The blood vessels and nerves are distributed in
the submucous coat. The inner, or mucous surface, has a
fine, velvety feeling, due to a countless number of tiny,
thread-like projections called villi. They stand up some-
what like the "pile" on velvet. It is through these villi
that the digested food passes into the blood.

The inner coat of a large part of the
small intestine is thrown into numerous
transverse folds called valvulce conniventes.
These serve to increase the extent of the
surface of the bowels and to delay mechani-
cally the progress of the intestinal contents.

167. The Peritoneum. The intestines
do not lie in a loose mass in the abdominal
cavity. Lining the walls of this cavity, just
as in a general way a paper lines the walls
of a room, is a delicate serous membrane
called the peritoneum. It envelops, in a
greater or less degree, most of the viscera
in the cavity, and forms folds by which
they are connected with one another, or are

attached to the posterior wall. Its arrange- (Villi are seen sur-

ment is therefore very complicated. When

the peritoneum comes in contact with the

large intestine, it passes over it just as

the paper of a room would pass over a gas

pipe which ran along the surface of the wall, and in passing

over it binds it down to the wall of the cavity.

The small intestines are suspended from the back wall of the
abdomen by a double fold of the peritoneum, called the mes-
entery. The bowels are also protected from external cold by
several folds of this membrane loaded with fat. This is known
as the great omentum.

y 168. The Large Intestine. The large intestine begins in
the right iliac region and is about five or six feet long. It
is much wider than the small intestine, which opens into

FIG. 55. A Small
Portion of the Mu-
cous Membrane of
the Small Intes-
tine.

rounded with the
openings of the tubu-
lar glands. Magni-
fied 20 diameters.)

H2 Life and Health

the side of the large intestine a short distance beyond the
beginning of the latter. A blind pouch, or dilated pocket,
is thus formed at the place of junction, called the caecum.

The large intestine passes upwards on the right side
as the ascending colon, until the underside of the liver is
reached, where it passes to the left
side as the transverse colon, below the
stomach. It there turns downward
as the descending colon, and making an
S-shaped curve, the sigmoid flexure, ends

• * * • " • « • .Li

• .-v? * * • • * . in the rectum,

•V«**;;I:rr; IBS. The Vermiform Appendix.

" ***** ° * * Attached to the caecum, and completing

FIG. 56. Sectional View its blind end> is a worm-shaped tube,

of Intestinal Villi. about the thickness of a lead pencil, and

(Black dots represent the fr°m thre6 tO f°Ur lncheS lonS' Called

glandular openings.) the vermiform appendix. It is of no use
in man, but in many of the lower ani-
mals it is much larger, and serves as an important digestive
pouch. This tube is of great surgical importance, from the
fact that it is subject to severe inflammation, often resulting
in an internal abscess, which is always dangerous and may
prove fatal.

Inflammation of the appendix is known as appendicitis, — a
name quite familiar on account of the many surgical opera-
tions performed of late years for its relief.

•f 170. The Liver. The liver is a large, reddish-brown organ,
situated just below the diaphragm and on the right side.
It is the largest gland in the body and weighs from fifty
to sixty ounces.

The liver is almost wholly covered by the ribs. In tight
lacing it is often forced downward, out from the cover of
the ribs, and thus becomes permanently displaced. As a
result, other organs in the upper abdomen and pelvis are
crowded together and also become displaced and distorted.

The Digestion of Food

171. The Hepatic Lobules. When a small piece of the
liver is examined under a microscope it is found to be
made up of masses of many-sided minute bodies, each
about T^Yo °^ an ^nch m diameter, called hepatic or liver
cells. The active work of the liver is done in the hepatic
cells.

Each group of cells is called a lobule, and they give to
the liver its coarse granular appearance when torn across.
Each lobule is attached to a branch of the hepatic vein,
the large vein which carries the blood away from the
liver. The lobules are polyhedral in shape, with their
cells arranged in rows, radiating from the center to the cir-
cumference. Minute channels separate the cells one from
another and unite in a main duct leading from the lobule.
' 172. The Portal Vein. There
is a large vessel, called the por-
tal vein, which during digestion
brings to the liver blood heav-
ily laden with the products of
.digestion, absorbed from the
stomach and intestines. On en-
tering the liver this great vek*=
conducts itself as if it were
an artery. It divides and sub-
divides into smaller and smaller
branches, until it ends in a net-
work of capillaries within that
organ.

A- 173. ~The Bile.
the

FIG. 57. Tubular Glands of
the Small Intestines.

A, B, tubular glands seen in verti-
cal section with their orifices at C
opening upon the membrane be-
tween the villi ; D, villus. (Mag-
nified 40 diameters.)

We have in

liver, on a grand scale,
exactly the same conditions that obtain in the smaller and
simpler glands. The thin-walled liver cells take from the
blood brought to them by the portal vein certain materials

H4 Life and Health

which they elaborate into an important digestive fluid
called the bile.1

This newly manufactured fluid is then carried away from
the liver in little canals, called bile ducts, which gradually
unite and form at last one main duct, known as the hepatic
duct. It passes out on the underside of the liver, and as
it approaches the intestine it meets at an acute angle the
cystic duct proceeding from the gall bladder and forms
with it the common bile duct, which opens obliquely into the
horseshoe bend of the duodenum.

The cystic duct leads back to the under surface of the
liver, where it expands into a sac capable of holding about
two ounces of fluid, known as the gall bladder (Fig. 58).

Experiment 46. To show the action of bile. Obtain from the
butcher some ox bile. Note its bitter taste, peculiar odor, and green-
ish color. It is alkaline or neutral to litmus paper. Pour it from
one vessel to another, and note that strings of mucin (from the lining
membrane of the gall bladder) connect one vessel with the other. It
is best to precipitate the mucin by acetic acid before making experi-
ments, and to dilute the clear liquid with a little distilled water.

Experiment 47. Test for bile pigments. Place a few drops of
bile on a white porcelain slab. With a glass rod place a drop or two
of strong nitric acid near the drop of bile ; bring the acid and bile
into contact. Notice the succession of colors, beginning with green,
and passing into blue, red, and yellow.

Experiment 48. To show the action of bile on fats. Mix three
teaspoonfuls of bile with one-half a teaspoonful of almond oil or
sweet oil. Shake well, and keep the tube in a water bath at about
1 00° Fahr. A very good emulsion is obtained.

1 The human bile when fresh is generally of a golden-yellow color and
of extremely bitter taste. It is slightly alkaline in reaction and contains a
great deal of pigment matter. When it has been vomited it is distinctly
yellow, because of its action on the gastric juice. About one pint of bile
is secreted in twenty-four hours.

The Digestion of Food 1 1 5

The bile, thus prepared in the depths of the liver by the
liver cells, is carried away by the bile ducts, and may pass
directly into the intestines to mix with the food. If, how-
ever, digestion is not going on, the mouth of the bile duct
is closed, and in that case the bile is carried by the cystic
duct to the gall bladder. Here it remains until such time
as it is needed.

X174. The Blood Supply of the Liver. We must not for-
get that the liver itself, being a large and important organ,
requires the constant nourishment of arterial blood to do
its work. This is furnished by the blood brought to it by
a great branch direct from the aorta, known as the hepatic
artery, minute branches of which, in the form of capillaries,
spread themselves around the liver lobules (Fig. 59).

The blood, having done its work and being now laden
with impurities, is picked up by minute veinlets, which
unite again and again till they at last form one great trunk
called the hepatic vein. This carries the impure blood from
the liver, and finally empties it into the vena cava inferior,
one of the large veins of the body.

After the blood brought by the portal vein to the liver
has been robbed of its bile-making materials, and otherwise
acted upon, it is collected by the veinlets that surround the
lobules and finds its way with other venous blood into
the hepatic vein.

In brief, blood is brought to the liver and distributed
through its substance by two distinct channels, — the
portal vein and the hepatic artery, — but it leaves the liver by
one channel, — the hepatic vein.

y 175, The Highly Important Work done by the Liver.
' We have thus far studied the liver only as an organ of secre-
tion, the work of which is to elaborate a complex fluid, called
bile, for future use in the process of digestion. This is,

n6

Life and Health

however, only one of* its functions, and perhaps not the
most important. In fact, the liver has many and complicated
tasks to perform, some of which are not fully understood.

CYSTIC PORTAL HEPATIC ROUND

ARTERY VEIN DUCT LIGAMENT

HEPATIC
ARTERY

FIG. 58. Showing the Relations of the Duodenum and Other

Intestinal Organs.
(A portion of the stomach has been cut away and the liver drawn up.)

The bile is not wholly a digestive fluid, but it contains
also materials which are separated from the blood to be
cast out of the body before they work mischief. Thus
the liver ranks above all others as an organ of excretion ; that

The Digestion of Food 117

is, it separates from the blood material that is of no further
use to the body and casts it out.

Of the various ingredients of the bile, only the bile salts
are of use in digestion. When mixed with pancreatic juice
they play an important part in aiding the emulsification and
saponifi cation of fats and their subsequent absorption.
^176. Glycogenic Function of the Liver. The third func-
.tion of the liver is different from those already described.
It is found that the liver of an animal well and regularly
fed, when examined soon after death, contains a quantity
of a carbohydrate substance not unlike starch. This sub-
stance, extracted in the form of a white powder, is really
an animal starch. It is called glycogen, or liver sugar, and
is easily converted into grape sugar or dextrose.

The hepatic cells appear to manufacture this glycogen
and to store it up from the products of digestion brought
by the portal blood. It is also thought that the glycogen
thus deposited and stored up in the hepatic, cells is little
by little changed into sugar. Then, as it is wanted, the
liver deals out this stored-up material by carrying it to
the tissues, as their needs demand, to supply them, with
material which can be oxidized to yield heat and motion.

/ 177. Formation of Urea by the Liver. There is evidence
to show that the liver has the power to make urea as well as
glycogen. Urea is the nitrogenous waste product which results
from the breaking down of proteid. An excess of proteid food
is probably broken up in the liver into glycogen and urea.
The glycogen is utilized, as we have stated, and the urea is got
rid of through the kidneys.

y 178. The Pancreas. The pancreas, or sweetbread, is a
gland from six to eight inches long, weighing from three
to four ounces, and is often compared in appearance to a
dog's tongue.

1 1 8 Life and Health

The pancreas lies behind the stomach, across the body,
from right to left, with its large head embraced in the
horseshoe bend of the duodenum. Its main duct enters
the duodenum in company with the common bile duct.
^ 179. The Action of Pancreatic Juice. The pancreas
secretes an alkaline digestive fluid called the pancreatic
juice. Combined with bile, this fluid acts upon the large
drops of fat which pass from the stomach into the duode-
num, and either emulsifies or saponifies them. Emulsified
fats consist of particles sufficiently minute to permit of
their absorption into the blood. Sapomfication is a chemi-
cal change in which the fat is broken up into glycerine and
a fatty acid, the latter combining with an alkali to form
a soap.

This most important digestive fluid also produces on
starch an action similar to that of saliva, but much more
powerful. During its short stay in the mouth, very little
starch is changed into sugar, and in the stomach the action
of the saliva is soon arrested. Now, the pancreatic juice
takes up the work in the small intestine and changes the
greater part of the starch into sugar. Nor is this all, for
it also acts powerfully upon the proteids not acted upon in
the stomach, and changes them into peptones that do not
differ materially from those resulting from gastric digestion.

The pancreatic juice is able to assist in digesting all
three kinds of foodstuffs because it contains three fer-
ments : trypsin, acting on proteids ; amylopsin, acting on
starches ; and steapsin, acting on fats.
4 180. Digestion in the Small Intestines. After digestion
in the stomach has been going on for some time, successive
portions of the semidigested food begin to pass into the
duodenum. The pancreas now takes on new activity, and
a copious flow of pancreatic juice is poured along its duct

The Digestion of Food 119

into the intestines. As the food is pushed along over the
common opening of the bile and pancreatic ducts, a great
quantity of bile from the reservoir, the gall bladder, is
poured into the intestines. These two digestive fluids are
now mixed with the chyme and act upon it in the remark-
able manner just described.

Experiment 49. To show the action of pancreatic juice on oils
or fats. Put two grains of pancreatin into a test tube. Add half a
teaspoonful of warm water, and shake well for a few minutes ; then
add a tablespoonful of sweet oil ; shake vigorously.

A creamy, opaque mixture of the oil and water, called an emul-
sion, will result. This will gradually separate upon standing, the
pancreatic extract settling in the water at the bottom. When shaken
it will again form an emulsion.

Experiment 50. To show the action of pancreatic juice on starch.
Put two tablespoonfuls of smooth starch paste into a goblet, and
while still so warm as just to be borne by the mouth, stir into it two
grains of the extract of pancreas. The starch paste will rapidly
become thinner, and gradually change into soluble starch, in a per-
fectly fluid solution. Within a few minutes some of the starch is con-
verted through intermediary stages into maltose and then into glucose.
Use the Fehling test for sugar.

Experiment 51. To show the action of pancreatic juice on the
albuminous ingredients (casein) of milk. Into a half-pint bottle (an
infant's nursing bottle will answer and is easily obtained) put two
tablespoonfuls of cold water; add one grain of pancreatin, and as
much baking soda as can be taken up on the point of a penknife.
Shake well, and add four tablespoonfuls of cold, fresh milk. Shake
again. Now set the bottle into a basin of hot water (as hot as one can
bear the hand in), and let it stand for about forty-five minutes.

While the milk is digesting, take a small quantity of milk in a
goblet, and stir in ten drops or more of vinegar. A thick, curd of
casein will be seen.

Upon applying the same test to the digested milk, no curd will be
made. This is because the pancreatic ferment (trypsin) has digested
the casein into " peptone," which does not curdle.

1 20 Life and Health

The inner surface of the small intestine also secretes a
liquid called intestinal juice, the precise functions of which
are not known. The chyme, thus acted upon by the dif-
ferent digestive fluids, resembles a thick cream and is now
called chyle. The chyle is thrust along the small intestine
by th.e contractions of its muscular walls.
-V 181. Digestion in the Large Intestines. Digestion does
not occur to any great extent in the large intestines. The
food enters this portion of the digestive canal through
the ileo-caecal valve and travels through it slowly. The
remains of the food now become less and less fluid, and
consist of undigested matter which has escaped the action
of the several digestive juices, or which has withstood their
influence. Driven onward by the contractions of the mus-
cular walls, the waste material at last reaches the rectum,
from which it is voluntarily expelled from the body.

ABSORPTION

182, Absorption. While food remains within the alimen-
tary canal it is outside of the body, so far as nutrition is
concerned. To be of any service the food must be absorbed
by the blood.

The efficient agents in absorption are the blood vessels
and the lymphatics. The process by which the nutritious
material enters the blood is called absorption. It is a
process not confined, as we shall see, simply to the
alimentary canal, but one that is going on in every tissue.
The vessels by which the process of absorption is carried
on are called absorbents, or lymphatics,
y. 183. Absorption by the Mouth and Stomach. The lining
of the mouth and oesophagus is not well adapted for
absorption. That this does occasionally occur, however,

The Digestion of Food

121

is shown by the fact that certain poisonous chemicals, like
cyanide of potash, if kept in the mouth for a few moments,
will cause death. While we are chewing and swallowing
our food, no doubt a certain amount of water and common
salt, together with sugar which has been changed from
starch by the action of the saliva, gains entrance to the

blood- pn^

In the stomach, however, absorption takes place

great-activity. The semiliquid food is separated from the
enormous supply of blood vessels in the mucous membrane

FIG. 59. Diagrammatic Scheme of Intestinal Absorption.

A, mesentery ; B, lacteals and mesentery glands ; C, veins of intestines ; R. C.}
receptacle of the chyle (receptaculum chyli) ; P. V., portal vein ; H. K, hepa-
tic veins ; S. V. C., superior vena cava ; R. A., right auricle of the heart ;
/. V. C., inferior vena cava.

only by a thin porous partition. Water, along with any
substances in the food that have become dissolved, will
pass through this partition and enter the blood current.
A certain amount of starch that has been changed into
sugar, of salts in solution, of proteids converted into pep-
tones, is also taken up directly by the blood vessels of
the stomach.

/ 184. Absorption by the Intestines. The greatest part of
absorption is accomplished by the small intestines. They

122

Life and Health

FIG. 60. Diagrammatic Scheme of a Trans-
verse Section of the Small Intestine.

(In the figure on the left are seen the artery and vein
of a villus. In the right figure are represented
the central chyle vessel of villus, with plexus of
lymph vessels at the base. The mucous, sub-
mucous, muscular, and serous coats are indicated
at the base of the right-hand figure. The epi-
thelium of each villus is well shown.)

have not only a very
large area of absorb-
ing surface, but also
structures especially
adapted to do this
work. It is a most
active and compli-
cated process.
**185. The Work
done by the Lacteals.
We have learned
that the mucous
lining of the small
intestines is crowded
with millions of little
appendages called
villi, meaning "tufts
of hair." These are
only about one-thir-
tieth of an inch long,
and a dime will cover
more than five hun-
dred of them. Each
villus contains a loop
of blood vessels, and
a special kind of lym-
phatics, called the
lacteals, so named
from the Latin word
lac, because of the
milky appearance
of the fluid they
contain.

The Digestion of Food 123

The villi are adapted especially for the absorption of fat.
They dip like the tiniest fingers into the chyle, and the
minute particles of_fat_j:>ajis through their cellular cover-
ing and gain entrance to the lacteals. The milky material
sucked up by the lacteals is not in a proper condition to be
poured at once into the blood current. It is, as it were, in
too crude a state, and needs some special preparation.

186, The Mesenteric Glands. The intestines are sus-
pended from the posterior wall of the abdomen by a double
fold of peritoneum, called the mesentery. That is, the
intestines are wrapped in a fold of the peritoneum some-
what as one would lie when slung in a hammock.

In this membrane are some one hundred and fifty
nodules about the size of an almond, called mesenteric glands.
Now the lacteals join these glands and pour in their milky
contents which they have just absorbed to undergo some
important changes. It is not unlikely that the mesenteric
glands may intercept, like a filter, material which, if allowed
to enter the blood, would disturb the whole body.

Having been acted upon by the mesenteric glands, and
passed through them, the chyle flows onward until it is
poured into the sac-like expansion of the lower end of the
thoracic duct, known as the receptaculum chyli. Into this
receptacle are poured not only the contents of the lacteals,
but also of the lymphatic vessels of the lower limbs.
1 187. The Thoracic Duct. This duct is a tube from fif-
teen to eighteen inches long, which passes upwards in front
of the spine to reach the base of the neck, where it opens
at the junction of the great veins on the left side of the
head with those of the left arm. Thus the thorackuduct
carries the nutritive material obtained from the 'iboa and
pours it into the blood current. It is to be remembered
that the lacteals are lymphatics — lymphatics of the intestines.

124

Life and Health

188. The Lymphatics. In nearly every tissue of the
body there is a marvelous network of vessels, precisely like
the lacteals, called the lymphatics. These are busily at
work taking up and giving out waste or surplus materials
derived from the blood and tissues generally. It is esti-
mated that the quantity of fluid exuded from the blood
and picked up by the lymphatics and restored daily to the
circulation is equal to the bulk of the blood in the body.

The minute branches
of the lymphatics, or
lymph capillaries, seem
to start out from the
part in which they are
found like the rootlets
of a plant in the soil.
They carry a turbid,
slightly yellowish fluid,
called lymph, which
seems to play the part
of a " middleman " be-
tween the blood on the
one hand and the tis-
sues on the other.
;Cl89. Work done by
the Lymphatics. Now,
just as the chyle was
not fit to be immediately taken up by the blood, but was
passed through the mesenteric glands to be properly worked
over, so the lymph is carried to small rounded or bean-shaped
bodies called lymphatic glands, where it undergoes certain
changes to fit it for being poured into the blood. Nature,
like a careful housekeeper, allows nothing to be wasted that
can be of any service in the body (Figs. 63 and 64).

FIG. 61. Section of a Lymphatic Gland.

A, strong fibrous capsule sending partitions into
the gland ; S, partitions between the follicles
or pouches of the cortical or outer portion ;
C, partitions of the medullary or central por-
tion ; D, £, masses of protoplasmic matter in
the pouches of the gland ; F, lymph vessels
which bring lymph to the gland, passing into
its center ; G, confluence of those leading to
the efferent vessel ; //, vessel which carries
the lymph away from the gland.

The Digestion of Food 1 2 5

The lymphatic vessels gradually unite to form larger
vessels and at last join the thoracic duct, except the lym-
phatics on the right side of the head and neck, on the
right arm and the right lung. These open by the right
lymphatic duct into the venous system on the right side
of the neck.

The whole lymphatic system may be regarded as a neces-
sary appendage to the blood-vascular system (Chapter VII).
It is convenient, however, to treat it under the general topic
of absorption, in order to complete the history of food
digestion.

/ 190. The Spleen and Other Ductless Glands. With the
lymphatics may be classified, for convenience, a number of
organs called ductless glands, because they have no ducts
or canals along which may be carried the result of their
work.

The spleen is the largest of these glands. It lies beneath
the diaphragm and upon the left side of the stomach. It is
of a deep-red color and full of blood.

The functions of the spleen are as yet but little under-
stood. It appears to take some part in the formation of blood
corpuscles. In certain diseases, like malarial fever, it may
become remarkably enlarged.

The spleen may be removed from man and from animals
without any apparent effect.

The thyroid is a ductless gland situated beneath the muscles
of the neck on the sides of "Adam's apple" and below it.
It undergoes great enlargement in the disease called goitre.

The thymus is also a ductless gland. It is situated around
the windpipe, behind the upper part of the breastbone. Until
about the end of the second year it increases in size, and then
it begins gradually to shrivel away. . Its use is not certainly
known.

The suprarenal capsules are two little bodies, one perched
on the upper edge of each kidney, in shape not unlike that
of a conical hat. Their functions are important, but as yet
nothing definite is known about them.

126

Life and Health

Experiment 52. Simple apparatus for illustrating endosmotic
action^ " Remove carefully a circular portion, about an inch in
diameter, of the shell from one end of an egg, which may be done
without injuring the membranes, by cracking the shell in small pieces,
which are picked off with forceps. A small glass
tube is then introduced through an opening in
the shell and membranes of the other end of the
egg, and is secured in a vertical position by wax
or plaster of Paris, the tube penetrating the yolk.
The egg is then placed in a wine-glass partly
filled with water, as in Fig. 62. In the course of
a few minutes the water will have penetrated the
exposed membrane, and the yolk will rise in the
tube." — FLINT'S Human Physiology.

Experiment 53. Stretch a piece of moist
bladder across a glass tube, — a common lamp
chimney will do. Into this put a strong sugar
or saline solution. Now suspend the tube in a
wide-mouthed vessel of water. After a short
time it will be found that a part of the sugar or
salt solution has passed through into the water,
while a larger amount of water has passed into
the tube and raised the height of the liquid
FIG. 62. within it.

T 191. The Quantity of Food as affected by Circumstances.
The quantity of food required to keep the body in proper
condition is modified to a great extent by circumstances.

1 The action produced by the tendency of fluids to mix, or become
equally diffused in contact with each other, is known as osmosis, a form of
molecular attraction allied to that of adhesion. The various physical
processes by which the products of digestion are transferred from the
digestive canal to the blood 'may be illustrated in a general way by these
simple experiments.

The student must, however, understand that the necessarily crude
experiments of the class-room may not conform in certain essentials to
4hose great processes conducted in the living body, which they are intended
to illustrate and explain.

The Digestion of Food

127

Age, occupation, place of residence, climate, and season,
as well as individual conditions of health and disease, are
always important factors in the problem.

192. The Quantity of Food as affected by Occupation,
Occupation has an important influence upon the quantity
of food demanded for the bodily support. Those who work
long and hard at physical labor need a generous amount
of nutritious food. A liberal diet of the cereals and' lean
meat, especially beef, gives that vigor to the muscles which
enables one to undergo labo-
rious and prolonged physical

exertion. On the other hand,
those who follow a seden-
tary occupation do not need
so large a quantity of food.
Brainworkers who would work
well and live long should not
indulge in too generous a diet.

193. Some of the 111 Effects
of a too Generous Diet. A gen-
erous diet, even of those who
take active muscular exercise,
should be indulged in only

with discretion. Frequent sick or nervous headaches, a
sense of fullness, bilious attacks, and dyspepsia are some of
the after-effects of eating more food than the body actually
requires.

If too much and too rich food be persistently indulged
in, the complexion is apt to become muddy, the skin,
especially of the face, pale and sallow and more or less
covered with blotches and pimples ; the breath may have
an unpleasant odor, and the general appearance of the
body may be unhealthy.

FIG. 63. Lymphatics and Lym-
phatic Glands of the Axilla.

128 Life and Health

194. Need of a Variety of Food. Food should be both
nutritious and digestible. Certain foods, as the vegetable
albumins, are both nutritious and digestible. A hard-work-
ing man may grow strong and maintain vigorous health on
most of them, even if deprived of animal food.

Animal food of some kind is, however, an economical and
useful addition to the diet. The common custom of eating
meat with bread and vegetables is a sound one.

The judicious admixture of different classes of foods
greatly aids their digestibility. The great abundance and
variety of food in this country permit this principle to be
put into practice. A variety of foods, as milk, eggs, vege-
tables, fruit, bread, and meat, may be wisely used to a
greater or less extent at every meal.

Oftentimes, where there is of necessity a sameness of
diet, there arises a craving for special articles of food.
Thus, on protracted voyages, and during long campaigns in
war, there is an almost universal craving for onions, raw
potatoes, and other vegetables.

195. A Few Suggestions about Meals. Every person in
good health, who takes a moderate amount of daily exercise,
should have a keen appetite for three meals a day.

The stomach, like other organs, does its work best at
regular periods. We should make it a point not to omit
a meal unless forced to do so. Children, and even adults,
often have the habit of going to school or to work in a
hurry, without eating any breakfast. There is almost sure
to be a faint or "all-gone" feeling at the stomach before
another mealtime.

Eating out of mealtimes should be strictly avoided, for
it robs the stomach of its needed rest. Food eaten when
the body and mind are wearied is not well digested. Rest,
even for a few minutes, should be taken before eating a

The Digestion of Food 129

full meal. It is well to lie down, or sit quietly and read,
fifteen minutes before eating, and directly afterwards.

Severe exercise and hard study just after a full meal
are very apt to delay or actually arrest digestion.

196. Practical Points about Eating. We should not eat
for at least two or three hours before going to bed. In
many cases of sleeplessness, however, a small quantity of
some simple food, especially if the stomach seems to feel
exhausted, often appears to promote sleep and rest.

The state of mind has much to do with digestion.
We should laugh and talk at our meals, and thus aim
to drive away anxious thoughts and avoid unpleasant
topics.

The proper chewing of the food is an important element
in digestion. Hence, eat slowly and do not "bolt" large
fragments of food.

Do not drink too much with the meals, for the flow of
the saliva is checked and digestion is hindered. If we
drink freely of ice water during meals, it takes some time
for the stomach to regain its natural heat.

It is a poor plan to stimulate a flagging appetite with
an undue amount of pepper, mustard, horseradish, pickles,
and highly seasoned meat sauces. They may stimulate
digestion for the time, but they soon impair it.

NOTE; The table on the next page shows the results of many

experiments to illustrate the time taken for the gastric digestion of a
number of the more common solid foods. There are a great many
factors of which the table takes no account, such as the interval since
the last meal, state of the appetite, amount of work and exercise,
method of cooking, and especially the quantity of food.

197. Hints about the Care of the Teeth. If an ounce
of prevention is ever worth a pound of cure, it is in keep-
ing the teeth in good order. Bad teeth and toothless gums

TABLE SHOWING THE DIGESTIBILITY OF THE
MORE COMMON SOLID FOODS

FOOD

How

COOKED

Time in
Stomach
(Hours)

FOOD

How

COOKED

Time in
Stomach
(Hours)

Apples, sweet and mel-
low . . ...

Raw

l£

Milk . "...

Raw

2\

Apples, sour and hard
Apple dumpling . .
Bass, striped, fresh .
Beans, pod ....
Beef, with salt only .

" fresh, lean . .

it u u

Boiled
Broiled
Boiled

Raw

Fried

4

3

4

2|

3

Mutton, fresh . . .

« a
tt u

Oysters, fresh . . .

it u

U It

Parsnips

Broiled
Boiled
Roasted
Raw
Roasted
Stewed
Boiled

3
3

3i

4

3i
3i

2.V

tt it

Roasted

i1

Pic

Roasted

•1

" old, hard, salted.
Beefsteak

Boiled
Broiled

oa

4i

Pig's feet, soused . .
Pork, recently salted .

Boiled
u

41

Beets

Boiled

i¥

u

Fried

4i

Baked

il

u

Raw

T

" wheat, fresh .
Butter

tt

Melted

j£
3*

a

" steaks ....
u

Fried
Stewed

34

3

Cabbage, with vinegar

u « tt

Raw
Boiled

2
4^

" fat or lean . .
Potatoes

Roasted
Baked

si
4

" heads

Raw

2^

«

Boiled

•71

Carrots . . . . . .

Boiled

^

u

Roasted

4

Cheese old strong

Raw

•A

Rice ...

Boiled

I

2?

Sago

if

" soup . . .
Codfish, cured, dried .
Corncake

Boiled

u

Baked

3

2
2?

Salmon, salted . . .
Soup, barley ....
" bean ....

u

u

4
4
3

Custard
Duck, domestic . . .
" wild ....
Eggs, fresh, whipped .

««

it

Roasted
u

Raw

a

2|

4
4l
4

2

" beef, vegetable
bread . . .
" marrow bone .
" mutton ... /
Sponge cake ....

tt
u

u

Baked

4
4i
3i

4

" soft-boiled . .

" hard-boiled . .
«

Boiled
Fried

3i
4

Suet, beef, fresh . .
" mutton . . .
Tapioca

Boiled

tt
it

54
4i

2

Fowl, domestic . . .

« «

Gelatin

Boiled
Roasted
Boiled

4
4
*ft

Tripe, soused . . .
Trout, salmon, fresh .

tt u u

u
(I

Fried

I
\\

Goose
Green corn and beans .
Hash, meat and vege-
tables

Roasted
Boiled

Warmed
Broiled

4

3l

4

2\

Turkey, wild . . .
" domestic . .

u tt

Turnips
Veal ......

Roasted
Boiled
Roasted
Boiled
Roasted

4
2i

4

34
4

Liver

u

2

tt

Fried

4i

Milk

Boiled

2

Venison, steaks . .

Broiled

4

130

The Digestion of Food

mean imperfect chewing of the food, and, hence, impaired
digestion. Decayed teeth are often the cause of an offen-
sive breath and a foul stomach.

The teeth should be thoroughly cleansed at bedtime and
in the morning with a soft brush and warm water. Some
prepared tooth powder without grit should be used, and the
brush should be applied
on both sides of the teeth.

When the enamel is
once broken through it
is never renewed. The
tooth decays, slowly but
surely ; hence we must
guard against certain
habits which injure the
enamel, as picking the
teeth with pins and
needles. We should
never crack nuts, crush
hard candy, or bite off
stout thread with the
teeth.

To remove fragments
of food which have lodged
between adjacent teeth,
a quill or wooden tooth-

FIG. 64. Lymphatics on the Inside
of the Right Hand.

pick should be used.

Even better than these

is the use of surgeon's floss or silk, which when drawn

between the teeth effectually dislodges retained particles.

If the teeth are not regularly cleansed they become dis-
colored, and a hard coating known as tartar accumulates
on them and tends to loosen them. It is said that after

132 Life aitd Health

the age of thirty more teeth are lost from this deposit
than from all other causes combined.

198. The Care of Children's Teeth. The teeth of children
should be often examined by the dentist, especially from the
beginning of the second dentition, at about the sixth year,
until growth is completed. In infancy the mother should
make it a part of her daily care of the child to secure perfect
cleanliness of the teeth. The child thus trained will not,
when old enough to rinse the mouth properly or to use the
brush, feel comfortable after a meal until the teeth have been
cleansed. The habit thus formed is almost sure to be con-
tinued through life.

199. Some Hints about saving Teeth. People are often
urged and consent to have a number of teeth extracted which,
with but little trouble and expense, might be kept and do
good service for years. The object is to replace the teeth
with an artificial set. Very few plates, either partial or entire,
are worn with real comfort.

Most drugs have no injurious effect upon the teeth. Some
medicines, however, must be used with great care. The acids
used in the tincture of iron have a great affinity for the lime
salts of the teeth. As this form of iron is often used it is not
unusual to see teeth* very badly stained or decayed from the
effects of this drug. The acid used in the liquid preparations
of quinine may destroy the teeth in a comparatively short
time. After taking such medicines the mouth should be thor-
oughly rinsed with a weak solution of common soda, and the
teeth carefully cleansed.

200. Effect of Alcoholic Beverages on the Gastric Diges-
tion. The mo.st marked effect of alcohol upon the stomach
is to irritate the gastric cells and cause an increased flow
of gastric juice. This abnormal irritation of the gastric
glands does not assist digestion, as might at first be sup-
posed, but serves to weaken the functional power of the
gastric juice.

After a time the stomach may gradually undergo last-
ing structural changes. Its blood vessels remain dilated

The Digestion of Food 133

and congested, its connective tissue becomes excessive, its
power of secreting gastric juice diminishes, and its mucous
secretion becomes abnormally abundant.1

As a result, the habitual user of alcoholic beverages usu-
ally surfers from the effects of a disordered and retarded
digestion, viz., obstinate dyspepsia and its familiar symp-
toms,— loss of appetite, acid eructation, nausea, vomiting,
headache, unnatural thirst, and mental depression. Remem-
ber that alcoholic drinks are not necessary or desirable to
arouse the appetite and stimulate digestion.

201. Effect of Alcohol upon the Liver. The portal vein,
as you should remember, brings the blood from the
stomach and intestines to the liver to be acted upon. Now
when alcohol, which is rapidly absorbed by the blood vessels
of the stomach, is brought to the liver, we should natu-
rally expect this great blood-purifying organ to suffer from a
marked effect of the narcotic. And so it does. The tissues
become at first irritated, then inflamed, and finally may be
seriously diseased. The fine bands, or septa, which serve
as partitions between the hepatic lobules seem to suffer
from prolonged alcoholic ingestion. The liver is at first
enlarged, but soon becomes contracted ; the secreting cells
are compressed, and are less able to perform their proper
work.

1 Professor Chittenden has made careful experiments upon the effect of
varying amounts of alcohol upon gastric digestion. He finds, in digestion
experiments made with mixtures of digestive juice outside the body, that
even small amounts of alcohol retard digestion. The same amounts cause
a slight increase in the secretion of gastric juice when taken into the body.
The retardation effects, however, somewhat more than neutralize the secre-
tion effects, for the experimenter says : " The results obtained suggest a
tendency towards prolongation of the period during which the meat
remains in the stomach when alcoholic fluids are present." — American
Journal of the Medical Sciences, vol. cxi ; American Journal of Physiology^

VOl. 1, pp. 202, 203.

134 Life and Health

202. Effect of Tobacco upon Digestion. Tobacco acts as
an irritant poison to the organs of digestion. It contains
a very poisonous substance known as nicotine.

The irritant properties of tobacco are shown in the
abnormal stimulation of the salivary glands. The excess
of saliva thus produced is expectorated or swallowed. The
normal quantity of saliva necessary for the proper diges-
tion of food is thus diminished.

203. Other Harmful Effects of Tobacco upon Digestion.
This unnatural secretion and loss of saliva, which especially
results from chewing tobacco, causes a dry ness of the
mouth and throat, often resulting in an unnatural thirst.
This thirst may tend to provoke a craving for alcoholic
liquors.

Tobacco users generally have a heavily coated tongue
and a foul breath, which are symptoms of a disordered con-
dition of the digestive organs.

In chewing tobacco, more or less of the nicotine is dis-
solved by the saliva and a part of it is swallowed. In smok-
ing, the nicotine in the vapor and smoke is absorbed by the
saliva and the mucous membranes. Thus, both in smoking
and chewing, the harmful effects of the nicotine are seen
in the irritation of all the tissues with which it comes in
contact. There may result loss of appetite, sinking feel-
ing, nausea, belching of gas, vomiting, distress after eating,
and other forms of indigestion so common with those who
habitually smoke or chew tobacco.1

1 Tobacco lessens the natural appetite, more or less impairs digestion,
and induces constipation, while it irritates the mouth and throat, rendering
it habitually congested, and destroying the purity of the voice. It induces
an habitual sense of uneasiness and nervousness, with epigastric sinking,
palpitation, and neuralgia. — ALFRED STILL£, Professor of Theory and
Practice of Medicine in the University of Pennsylvania.

The Digestion of Food 135

ADDITIONAL EXPERIMENTS

Experiment 54. Test a portion of C (Experiment 42) with solution
of iodine ; no blue color is obtained, as all the starch has disappeared,
having been converted into sugar, or maltose.

Experiment 55. To show the action of gastric juice on milk.
Mix two teaspoonfuls of fresh milk in a test tube with a few drops of
neutral artificial gastric juice j1 keep at about 100° Fahr. In a short
time the milk curdles, so that the tube can be inverted without the
curd falling out. By and by whey is squeezed out of the clot. The
curdling of milk by the rennet ferment present in the gastric juice is
quite different from that produced by the " souring of milk," or by the
precipitation of caseinogen by acids. Here the casein (carrying with
it most of the fats) is precipitated in a neutral fluid.

Experiment 56. To the test tube in the preceding experiment add
two teaspoonfuls of dilute hydrochloric acid, and keep at 100° Fahr.
for two hours. The pepsin in the presence of the acid digests the
casein, gradually dissolving it, forming a straw-colored fluid containing
peptones. The peptonized milk has a peculiar odor and bitter taste.

Experiment 57. To show the action of rennet on milk. Place
milk in a test tube, add a drop or two of commercial rennet, and place
the tube in a water bath at about 100° Fahr. The milk becomes solid
in a few minutes, forming a curd, and by and by the curd of casein
contracts, and presses out a fluid, — the whey.

Experiment 58. Repeat the experiment, but previously boil the
rennet. No such result is obtained as in the preceding experiment,
because the rennet ferment is destroyed by heat.

1 An artificial gastric juice may be obtained for experimental purposes
by dissolving about ten grains of pepsin powder (made by some reputable
manufacturer and obtained of any druggist) in half a pint of water and
adding perhaps fifteen to twenty drops of strong hydrochloric acid, or
about two teaspoonfuls of the dilute acid.

CHAPTER VII

THE BLOOD AND ITS CIRCULATION

J 204. Physical Properties of Blood. The blood is a red,
warm, heavy, alkaline fluid, slightly salt in taste, and has
a somewhat fetid odor. Its color varies from bright red in
the arteries and when exposed to the air, to various tints,
from dark purple to red, in the veins.

The temperature of the blood varies slightly in different
parts of the circulation. Its average temperature near the
A surface is in health about the

same, viz., 98 1° Fahr. The total
*H amount of the blood in the body
is about one-thirteenth of its

total weight.

•* 205. Blood Corpuscles. If we

put a drop of fresh blood upon a

FIG 65. Red Blood Corpuscles kss slide and kce k a

of Vanous Animals. (Magni- c .

fied to the same scale.) cover of thin glass, we can flatten

A, from proteus, a kind of newt; it OUt Until the Color almost dis-

B, salamander; c, frog; D, frog appears. If we examine this thin

after addition of acetic acid, show- *-

ing the central nucleus ; £, bird; film With a miCrOSCOpe, WC SCC

F, camel; G, fish; H, crab or that the blood is not altogether

other invertebrate animal. _ . . ,,, r , - . .. .,

fluid. We find that the liquid

part, or plasma, is of a light straw color, and has floating
in it a multitude of very minute bodies, called corpuscles.

There are two kinds of corpuscles, red and white.
"* 206. The Red Corpuscles. The red corpuscles are circular
disks about 7^W of an inch in diameter, and doubly

136

The Blood and its Circulation

137

concave in shape. They tend to adhere in long rolls like
piles of coins. They are soft, flexible, and elastic, readily
squeezing through passages narrower than their own diame-
ter, then at once resuming their own shape.

The principal constituent of these corpuscles, and that
which gives them color, is hcemoglobin, a compound con-
taining iron and a colorless proteid substance.
A very important office of the red corpuscles
is to act as carriers of oxygen from the lungs
to all of the tissues.

/• 207. The White Corpuscles. The white cor-
puscles are larger than the red, their average
diameter being about ^Vfr °^ an mc^- They
are of very irregular shape and stick close to
the glass slide on which they are placed.

The white corpuscles spontaneously undergo
active and curious changes of form, resembling
those of the amoeba, a very minute organism
found in stagnant water (Fig. 2).

The white corpuscles have been called the
warrior-cells of the bodily tissues, forever
battling against the invasion of bacteria.
They have the power of moving about among
the tissues and picking up foreign particles,
thus acting as little scavengers.
/ 208. The Clotting or Coagulation of Blood.
When blood is drawn directly from the blood
vessels of an animal into a cup it is at first
as fluid as water ; but in a few minutes it
becomes a jelly-like mass, called a clot. The cup contain-
ing it can be, turned upside down, without a drop of blood
being spilled. If carefully shaken out, the mass will form
a complete mould of the vessel.

FIG. 66. Hu-
man Blood
Corpuscles.

A, red corpus-
cles; B, the
sa me seen
edgeways; C,
the same ar-
ranged in
rows; D ,
white corpus-
cles with nu-
clei.

138

Life and Health

At first the clot includes the whole mass of blood and
is of a uniform color. But in a short time a pale yellowish

fluid begins to ooze
out and to collect
on the surface.
The clot gradually
shrinks, until at the
end of a few hours it
is much firmer and
floats in the yellowish
fluid.

This remarkable
process is known as
coagulation, or the clot-
ting of blood ; and the
liquid which separates

FIG. 67. Human Red and White Blood Cor- from the clot is called
puscles, as seen under the Microscope. serum.

(Magnified 1000 diameters. Two white corpuscles The prOCCSS of the
are seen, with their nuclei stained to show black.) clotting of blood is not

yet fully understood,

but is claimed "to be due in part to the action of a fer-
ment in the white corpuscles which produces a substance
called fibrin.

Experiment 59. To show the blood corpuscles. A moderately
powerful microscope is necessary to examine blood corpuscles. Let
a small drop of blood (easily obtained by pricking the finger with a
needle) be placed upon a clean slip of glass and covered with thin
glass such as is ordinarily used for microscopic purposes.

The blood is thus spread out into a film and may be readily
examined. At first the red corpuscles will be seen as pale, disk-like
bodies floating in the clear fluid. Soon they will be observed to stick
to each other by their flattened faces, so as to form rows. The white
corpuscles are to be seen, but are much less numerous.

The Blood and its Circulation

'39

V209. Why the Clotting of Blood is of Vital Importance.

This clotting of the blood is of vital importance. But for
this, a very small cut might cause bleeding sufficient to
empty the blood vessels, and death would speedily follow.
In slight cuts, Nature plugs up the
wound with clots of blood, and thus B— — -]
prevents excessive bleeding.

Experiment 60. Put two or three drops of
fresh blood on a white individual butter plate
inverted in a saucer in which is a little water.
Cover it with an inverted goblet. Take off
the cover in five minutes, and the drop has set
into a jelly-like mass. Take it off in half an
hour, and a little clot will be seen in the watery
serum.

D—

FIG. 68. Diagram of
Clot with Buffy Coat.

A, serum ; 5, cupped up-
per surface of clot ; C,
white corpuscles in up-
per layer of clot; D,
lower portion of clot
with red corpusdes.

Experiment 61. To show the blood clot.
Carry to the slaughter house a clean six or
eight ounce wide-mouthed bottle. Fill it with fresh blood. Carry
it home with great care, and let it stand over night. The next day
the clot will be seen floating in the nearly colorless serum.

Experiment 62. Obtain a pint of fresh blood ; put it into a bowl
and whip it briskly for five minutes with a bunch of dry twigs. Fine
white threads of fibrin collect on the twigs, the blood remaining fluid.
This is "whipped," or defibrinated blood, which has lost the power
of coagulating spontaneously.

NOTE. — Fresh blood may be prevented from clotting by adding
to it one-fourth part of a saturated solution of Epsom salt and keep-
ing it in a cool place. By adding ten times its amount of water, the
" salted " blood may be made to clot.

V 210. The Apparatus for the Circulation of the Blood.

The apparatus for the circulation of the blood consists of
the heart, the arteries, the capillaries, and the veins.
The central pump is the heart.

140

Life and Health

The pipes leading from it and gradually growing smaller
and smaller are the arteries.

The very minute vessels into which they lead at last
are capillaries.

The pipes which convey the blood back to the heart are
the veins.

211. The Heart. The heart is a pear-shaped, muscular

organ, roughly esti-
mated as about the size
of the closed fist of the
person to whom it be-
longs. It lies in the
chest behind the breast-
bone and is lodged
between the lobes of
the lungs, which partly
cover it.

In health the apex of
the heart beats against
the chest wall between
the fifth and sixth ribs,
about an inch and a
half to the left of the
middle line of the body.
The beating of the

FIG. 69. Anterior View of the Heart. heart can be readily

A, superior vena cava ; B, right auricle ; C, right felt, heard, and often
ventricle; Dt left ventricle ; E, left auricle; seen moving the chest

_ °
Wall as it Strikes

aSclinst it

^212. The Pericar-
dium. The heart is enclosed in a bell-shaped covering,
called the pericardium. This is really double, with two

F, pulmonary vein ; //, pulmonary artery ;
K, aorta ; L, right subclavian artery ; M, right
common carotid artery; JV, left common ca-

The Blood and its Circulation

141

layers, one over the other. The inner (or visceral) layer
covers the external surface of the heart and is reflected
back upon itself in order to form, like all membranes of
this kind, a sac without an opening. The space between
the two membranes is filled with
fluid which permits the heart and
the pericardium to glide one upon
the other with the least friction.1

FIG. 70. Diagram illus-
trating the Structure of*
a Serous Membrane.

A, the viscus, or organ, envel-
oped by serous membrane ;
B, layer of membrane lin-
ing cavity; C, membrane
reflected to envelop viscus ;
D, outer layer of viscus,
with blood vessels at R
communicating with the
general circulation.

213. Serous Membranes. The serous
membranes form shut sacs, one portion
of each of which is applied to the walls
of the cavity which it lines ; the other is
reflected over the surface of the organ
or organs contained in the cavity. The
sac is completely closed, so that no com-
munication exists between the serous
cavity and the parts in its neighbor-
hood. These membranes secrete a
fluid, commonly called serum, but which
is really a form of lymph. The various
serous membranes are \hzpleura, which
envelops the lungs ; the pericardium,
which surrounds the heart ; and the
peritoneum, which invests the viscera of the abdomen. In health
the serous membranes secrete only sufficient fluid to lubricate
and keep soft and smooth the opposing surfaces.

/ 214, The Auricles and Ventricles. The heart is a hollow
organ, divided into two great cavities or "chambers" by a
fixed partition forming a left and a right side. These two
cavities are each divided transversely by a movable par-
tition into an upper and a lower chamber. These partitions,

1 A correct idea may be formed of the arrangement of the pericardium
around the heart by recalling how a boy puts on and wears his toboggan
cap. The pericardium encloses the heart exactly as this cap covers the
boy's head.

142

Life and Health

however, include a set of valves which open like folding

doors between the two rooms.

The heart thus has four cavities, two on each side. The

two upper are called auricles, from the resemblance of one

corner of each to the ear of a
dog. The two lower cavities
are called ventricles.
4 215. The Valves of the
Heart. The valves of the heart
consist of thin, but strong,
triangular folds of connective
tissue which hang down from
the edges of the passages into
the ventricles. They may be
compared to swinging doors
which, by opening only one
way, allow the blood to flow
from the auricles to the ven-
tricles, but by instantly fold-
ing back prevent its return.

The valve on the right side
is called the tricuspid, because
it consists of three little folds
which fall over the opening
and close it. It is kept from
falling too far by a number of
slender threads called chordae
tendineae.

The valve on the left side,
called the mitral, from its

fancied resemblance to a bishop's miter, consists of two

folds which close together as do those of the tricuspid

valve.

FIG. 71. Right Cavities of
the Heart.

A, aorta ; B, superior vena cava ; C, C,
right pulmonary veins ; D, inferior
vena cava; £, section of coronary
vein; F, right ventricular cavity;
H, posterior curtain of the tricuspid
valve; K, right auricular cavity;
Af, fossa ovalis, oval depression, par-
tition between the auricles formed
after birth.

The Blood and its Circulation

The Semilunar Valves. From the right ventricle
a large vessel, called the pulmonary artery, passes to the
lungs, and from the left ventricle a large vessel, called the
aorta, arches out to the general
circulation of the body. The
openings from the ventricles
into these vessels are guarded
by the semilunar valves. Each
valve has three folds, each half-
moon shaped, hence the name
" semilunar." These valves,
when shut, prevent any back-
ward flow of the blood from
the pulmonary artery to the
right ventricle, and from the
aorta to the left ventricle.
Y. 217. The Great Blood Vessels
connected with the Right Side
of the Heart. There are a few
large blood vessels connected
with the heart, the relative
position and the use of which
must be understood.

The two largest veins in the
body, the superior vena cava and
the inferior vena cava, open into
the right auricle. They bring
venous blood from all parts of
the body and pour it into the right auricle.

From the right ventricle arises one large vessel, the pul-
monary artery, which soon divides into two branches of
nearly equal size, one for the right lung, the other for
the left.

FIG. 72. Left Cavities of

the Heart.

, £, right pulmonary veins ; with S,
openings of the veins; £, D, C,
aortic valves; fi, aorta; P, pulmo-
nary artery; O, pulmonic valves;
H, mitral valve ; K, columnae car-
nceae ; M, right ventricular cavity ;
N, interventricular septum.

144 Life and Health

^ 218. The Great Blood Vessels connected with the Left
Side of the Heart. Let us now turn to the left side of
the heart and study the general plan of its great vessels.
Four veins, called the pulmonary veins, open into the left
auricle, two from each lung. They start from very minute

FIG. 73. Lateral Section of the
Right Chest.

(Showing the relative position of the
heart and its great vessels, and of
the oesophagus and trachea.)

A, inferior constrictor muscle (aids in
conveying food down the oesopha-
gus) ; B, oesophagus ; C, section of
the right bronchus ; D, two right
pulmonary veins; E, great azygos
vein crossing oesophagus and right
bronchus to empty into the superior
vena cava; F, thoracic duct; H,
thoracic aorta ; K, lower portion of
oesophagus passing through the dia-
phragm; L, diaphragm as it ap-
pears in sectional view, enveloping
the heart; M, inferior vena cava
passing through diaphragm and
emptying into auricle; N, right
auricle ; O, section of right branch
of the pulmonary artery ; P, aorta ;
R, superior vena cava ; S, trachea.

vessels and form larger and larger vessels until they become
two large veins in each lung, and pour their contents into
the left auricle.

Remember, then, that the pulmonary artery carries venous
blood from the right ventricle to the lungs, and that the

The Blood and its Circulation 145

pulmonary veins carry arterial blood to the left auricle from
the lungs.

From the left ventricle springs the largest arterial trunk
in the body, called the aorta. From the aorta other arteries
branch off to carry the blood to all parts of the body.
X 219, The Arteries. The blood vessels are tubes through
which the blood is carried to and from the tissues. There
are three kinds, — the arteries, the veins, and the capillaries.

The arteries are the highly elastic and extensible tubes
which carry the blood from the heart to all parts of the
body. All the arteries except the pulmonary may be
regarded as branches of the aorta.

^ 220. The Aorta and its Great Branches. After the aorta
leaves the left ventricle it rises towards the neck, but soon
turns downwards, making a curve known as the arch of
the aorta.

From the arch are given off the arteries which supply
the head and arms with blood. These are the two carotid
arteries, which run up on each side of the neck to the head,
and the two subclavian arteries, which pass beneath the
collar bone to the arms.

The aorta now passes down in front of the spine to the
pelvis, giving off arteries to the different organs. Of these
branches the chief are the coaliac artery, which supplies the
stomach, the liver, and the spleen ; the renal arteries, one
to each kidney ; and the mesenteric arteries, which supply
the intestines.

The aorta at last divides into two main branches, the
common iliac arteries, which, by their subdivisions, furnish
the arterial vessels for the pelvis and the lower limbs.

221, The Veins. The veins are the blood vessels which
carry the impure blood from the various tissues of the body
to the heart. They begin in the minute capillaries and,

146

Life and Health

passing onwards toward the heart, at length form the two

great vessels which open into the right auricle.

These two great venous trunks are the inferior vena cava,

which brings the blood from the trunk and the lower limbs,

and the superior vena cava, which brings the blood from the

head and the upper limbs.

The four pulmonary veins, as we have learned, carry the

arterial blood from the lungs to the left auricle.

Many of the veins lie near the surface of the body.

Some of them may be easily seen under the skin of the
hand and forearm, especially if the
arm is allowed to hang down a few
moments.

222. How the Blood flows in the
Veins. The walls of the larger veins
are thin, and when empty they col-
lapse. The inner surfaces of many
of the veins are supplied with pouch-
like folds, or pockets, which act as
valves to prevent the backward flow
of the blood. These valves can be

FIG. 74.

A, part of a vein laid open,

with two pairs of valves; shown b letting the forearm hang

B, longitudinal section of J 5

a vein, showing the valves down and sliding the finger upwards
over the veins.

The onward flow of the blood in the veins is due to
various causes, the chief being the pressure behind of the
blood pumped into the capillaries. Then as the pocket-
like valves prevent the backward flow of the blood, the
pressure of the various muscles of the body urges along
the blood and thus promotes the onward flow.

223. The Capillaries. The capillaries are minute tubes,
with very thin walls, which form the connection between
the ending of the finest arteries and the beginning of the

The Blood and its Circulation

smallest veins. They are distributed through every tissue
of the body, except the epidermis and its appendages, the
epithelium, the cartilages, and the enamel of the teeth.
/ 224. The Work done by the Capillaries. The capillaries
are closed vessels, and the space between the walls of the
capillaries and the cells of the tissues is filled with lymph.
As the blood flows along the capillaries, certain parts of
the plasma of the blood filter through their walls into the
lymph, and certain parts of the
lymph filter in the opposite direc-
tion through the walls of the capil-
laries and mingle with the blood
current.

A similar exchange of material
is constantly going on between the
lymph and the tissues themselves,
so that the lymph acts as a medium
of exchange between the blood and
the tissues.

In brief, the tissues, with the lymph as a kind of "middle-
man," may be said to live on the blood.

.Experiment 63. Grasp the left wrist tightly with the thumb and
two fingers of the right hand. Note the little knots or swellings in
the veins caused by checking the flow of the venous blood towards the
heart. These swellings show the location of the valves of the veins.

225. The Pulmonary, or Lesser, Circulation. Let us now
study the circulation as a whole, tracing the course of the
blood from a certain point until it returns to the same
point. We may conveniently begin with the portion of
blood contained at any moment in the right auricle.

The superior and inferior venae cavae are busily filling the
right auricle with dark, impure blood. When it is full it
contracts. The passage leading to the right ventricle lies

FIG. 75. The Structure
of Capillaries.

(Capillaries of various sizes,
showing cells with nuclei.)

148

Life and Health

open and through it the blood pours till the ventricle is
full. Instantly this begins, in its turn, to contract. The
tricuspid valve at once closes and blocks the way backward.
The blood is now forced through the open semilunar valves

into the pulmonary
artery.

The pulmonary
artery, bringing ve-
nous blood, by its
alternate expansion
and recoil draws the
blood along until it
reaches the pulmo-
nary capillaries. These
tiny tubes surround
the air spaces of the
lungs, and here an
exchange takes
place. The dark,
venous blood here
gives up its waste in
the form of carbon
dioxide and water,
and in return takes
up a large amount of
oxygen and becomes
bright red. Thus the
blood brought to the lungs by the pulmonary arteries leaves
the lungs entirely different in character and appearance.
This is often called the pulmonary, or lesser, circulation.
226. The Systemic, or Greater, Circulation. The four pul-
monary veins bring back bright scarlet blood and pour it into
the left auricle of the heart, whence it goes past the mitral

FIG. 76. Showing the Carotid Artery and
Jugular Vein on the Right Side, with Some
of their Main Branches.
(Some branches of the cervical plexus, and the
hypoglossal nerve are also shown.)

The Blood and its Circulation

149

valve into the left ventricle. As soon as the left ventricle
is full, it contracts. The mitral valve instantly closes and
blocks the passage backward into the auricle ; the blood,
having no other way open, is
forced past the semilunar valves
into the aorta. •

Now red in color from its
fresh oxygen, and laden with
nutritive materials, the blood is
distributed by the arteries to
the various tissues of the body.
Here it gives up its oxygen and
certain nutritive materials to
build up the tissues, and receives
certain products of waste, and,
changed to a purple color, passes
from the capillaries into the veins.

All the veins of the body,
except the pulmonary veins and
those from the lungs and the
heart itself, unite into the two
large veins, as already described,
which pour their contents into
the right auricle of the heart, and
thus the grand round of circula-
tion is continually maintained.

This is often called the syste-
mic, or greater, circulation.
/227. The Portal Circulation.
A certain part of the systemic,
or greater, circulation is often called the portal circulation. By
this is meant the flow of the blood from the abdominal vis-
cera through the portal vein and liver to the hepatic vein.

FIG. 77. Diagram illustrating
the Circulation.

1, right auricle; 2, left auricle; 3,
right ventricle ; 4, left ventricle ;
5, vena cava superior; 6, vena
cava inferior ; 7, pulmonary ar-
teries; 8, lungs; 9, pulmonary
veins ; 10, aorta ; 11, alimentary
canal; 12, liver; 13, hepatic ar-
tery; 14, portal vein ; 15, hepatic
vein.

1 50 Life and Health

The blood brought to the capillaries of the stomach,
intestines, spleen, and pancreas is gathered into veins
which unite into a single trunk called the portal vein. The
blood, thus laden with certain products of digestion, is
carried to the liver by the portal vein, mingling with that
supplied to the capillaries of the same organ by the hepatic
artery. From these capillaries the blood is carried by small
veins which unite into a large trunk, the hepatic vein, which
opens into the inferior vena cava.

The portal circulation is thus not an independent system,
but forms a kind of loop on the systemic circulation.

Experiment 64. To illustrate the action of the heart, and how it
pumps the blood in only one direction. Take a household rubber
bulb syringe of any standard make. Sink the suction end into water
and press the bulb. As you let the bulb expand, it fills with water ;
as you press it again, a valve prevents the water from flowing back,
and it is driven out in a jet along the other pipe. The suction pipe
represents the veins ; the bulb, the heart ; and the tube end, out of
which the water flows, the arteries.

228. The Rhythmic Action of the Heart. To maintain a
steady flow of blood throughout the body the action of the
heart must be regular and methodical. The heart does not
contract as a whole. The two auricles contract at the same
time, and this is followed at once by the contraction of the two
ventricles. While the ventricles are contracting, the auricles
begin to relax, and after the ventricles contract they also relax.
Now comes a pause, or rest, after which the auricles and ven-
tricles contract again in the same order as before, and their
contractions are followed by the same pause as before. This
cycle of changes is known as the rhythmic action of the heart.

*/ 229. The Beat, or Impulse, of the Heart. If the hand be
laid flat over the chest wall on the left, between the fifth
and sixth ribs, the heart will be felt beating. This move-
ment is known as the beat, or impulse, of the heart, and can be

The Blood and its Circulation

both seen and felt on the left side. The heart beat is unu-
sually strong during active bodily exertion and under mental
excitement. This is commonly known as palpitation.
^VThe impulse of the heart is due to the striking of the
lower, tense part of the ventricles — the apex of the heart
— against the chest wall at
the moment of their vigor-
ous contraction.
^c 230. The Sounds of the
Heart. If the ear be applied
over the region of the heart,
two distinct sounds will be
heard. Their character may
be tolerably imitated by pro-
nouncing the syllables "lub,"
" dup." One sound is heard
immediately after the other,
then there is a pause, then
come the two sounds again.
The first is a dull, muffled
sound, known as the " first
sound," followed at once by
a shorter and sharper sound,

FIG. 78. Muscular Fibers of
the Ventricles.

A, superficial fibers common to both ven-
tricles; B, fibers of the left ventricle;
C, deep fibers passing upwards towards
the base of the heart ; D, fibers penetrat-
ing the left ventricle.

known as the "second
sound" of the heart.

The precise cause of the
first sound is not certainly

known, but the second sound is, without doubt, caused by
the sudden closure of the semilunar valves of the pul-
monary artery and the aorta, at the moment when the
contraction of the ventricles is completed.
><^2.31. The Nervous Control of the Heart. The regular,
rhythmic movement of the heart is maintained by the action

1 5 2 Life and Health

Q &uw QXA^ \ b-jJ£uuoLQ -MjLAAM^fc

of Certain _ nejry.es. Within the substance of the heart are
masses of nerve matter called ganglia. From these gan-
glia there proceed, at regular intervals, discharges of nerve
energy, some of which excite movement, while others seem
to restrain it.

The heart is also subject to nerve influences from out-
side of itself. Two nerves are connected with the heart,
the pneumogastric and the sympathetic (sees. 332 and 342).
The former appears to be connected with the restraining
ganglia, the latter with the exciting ganglia,
v 232. The Nervous Control of the Blood Vessels. The tone
and caliber of the blood vessels are controlled by certain
vaso-motor nerves, which are distributed among the muscular
fibers of the walls. These nerves are governed from a
center in the medulla oblongata (sec. 330).

Now the vaso-motor center may be excited to increased
activity by influences reaching it from various parts of the
body, or even from the brain itself. As a result, the nerves
are stimulated, and the vessels contract. Again, the normal
influence of the vaso-motor center may ba suspended for a
time by what is known as the inhibitory, or restraining effect.
The result is that the tone of the blood vessels becomes
diminished, and their channels widen.

The effect of this action of the nervous system is to give
it a certain control over the circulation in particular parts.
Thus, though the force of the heart and the general average
blood pressure remain the same, the state of the circulation
may be very different in different parts of the body.
• 233. The Importance of this Nervous Control. This local
control over the circulation is of the utmost importance.
Thus, when an organ is at work it needs to be more richly
supplied with blood than when at rest. For example, when
the salivary glands need to secrete saliva, and the stomach

The Blood and its Circulation

153

PAROTID GLAND

COMMON CAROTID AK\

BRACHML ARTCRY.
BRACHIAL VEIN

ffAOML ARTERY
flADIAL VEIN

FIG. 79. Showing Principal Muscles on the Right, Certain Organs of the
Chest and Abdomen, and the Larger Blood Vessels on the Left.

154 Life and Health

to pour out gastric juice, the arteries that supply these
organs are dilated, and so the parts are flushed with an
extra supply of blood, and thus are aroused to greater
activity.

Again, the ordinary supply of blood to a part may be
lessened, so that the organ is reduced to a state of inac-
tivity, as occurs in the case of the brain during sleep. We
have in the act of blushing a familiar example of sudden

FIG. 80. The Right Axillary
and Brachial Arteries,

with Some of their
- Main Branches.

enlargement of the smaller arteries of the face and neck,
called forth by some emotion which acts on the vaso-motor
center and diminishes its activity.

Experiment 65. Hold up the ear of a white rabbit against the light
while the animal is kept quiet and not alarmed. The red central artery
can be seen coursing along the translucent organ, giving off branches
which by subdivision become too small to be separately visible, and
the whole ear has a pink color and is warm from the abundant blood
flowing through it. Attentive observation will show also that the
caliber of the main artery is not constant; at somewhat irregular
periods of a minute or more it dilates and contracts a little.

234. The Pulse. When the finger is placed on any part
of the body where an artery is located near the surface, as,

The Blood and its Circulation

155

for example, on the radial artery near the wrist, there is
felt an intermittent pressure, throbbing with every beat of
the heart. This movement, frequently visible to the eye,
is the result of the alternate expansion of the arterial walls
by the wave of blood, and the recoil by their elasticity. In
other words, it is the wave produced by throwing a mass of
blood into the arteries already full. The blood wave strikes
upon the elastic walls of the
arteries, causing an increased
distention, followed at once
by contraction.

This intermittent rise and
fall of the arterial wall felt
just under the ringers, which
corresponds to the successive
heart beats, is known as the
pulse.

This wave of distention,
or the pulse, may be easily
felt at the wrist, the temple,
and the inner side of the ankle. The throb of the two
carotid arteries may be plainly felt by pressing the thumb
and ringer backwards on each side of the larynx.

235. The Pulse Wave. The progress of the pulse wave
must not be confused with the actual current of the blood
itself. For instance, the pulse wave travels at the rate of
about thirty feet a second, and takes about one-tenth of a
second to reach the wrist, while the blood itself is from
three to five seconds in reaching the same place. The
pulse wave may be compared to the wave produced by a
stiff breeze on the surface of a slowly moving stream.

236. How the Pulse Rate may be modified. The rate of
the pulse is modified by age, fatigue, posture, exercise,

FIG. 81. Capillary Blood Vessels
in the Web of a Frog's Foot, as
seen with the Microscope.

156 Life and He a Ith

disease, and many other circumstances. At birth the rate is
about 140 times a minute; in early infancy, 1 20 or upwards ;
in the healthy adult, between 65 and 75, the more common
number being 72.

In the same individual the pulse is quicker when stand-
ing than when lying down, is quickened by excitement, is
faster in the morning, and is slowest at midnight.

As the pulse varies much in its rate and character in
disease, it is to the skilled touch of the physician an invalu-
able help in the diagnosis of the physical condition of his
patient.

Experiment 66. Press three fingers over the radius to find the
pulse in the wrist. Note by a watch the rate of the beat per minute.
Take a friend's pulse in the same way and compare the character,
istics of the two.

Observe how the character and frequency of the pulse are altered
by posture, muscular exercise, a prolonged, sustained, deep inspiration,
prolonged expiration, and other conditions.

237. Effect of Alcohol upon the Blood. Alcohol is rapidly
absorbed, unchanged by the capillaries of the stomach, and
is carried directly into the general circulation and dis-
tributed throughout the body.

The red blood corpuscles, as we have just learned, are
the great oxygen carriers. Now alcohol has such a strong
affinity for oxygen that good authorities believe it plays
the part of a highwayman and robs the red corpuscles of
a portion of their oxygen.

Again, it is claimed that the white blood corpuscles
have a certain germicidal power, but that they are so acted
upon by the presence of alcohol that they become less
active in defending the system against the germs of
disease.

The Blood and its Circulation 1 5 7

238, First Effect of Alcohol upon the Circulation. When
alcohol is taken in moderate quantities by a person in health
the pulse beats faster and usually less regularly, the circu-
lation becomes more rapid, and the blood passing rapidly
through the tissues yields to them less of its oxygen.
From this it is evident that under these conditions the
blood is not doing its full work.

This early stage in the action of alcohol lasts for only
a short time, and is followed by a reaction in which the
strength and rapidity of the
heart beats fall even below the
point at which they were working
when the dose of alcohol was
given. Thus the total amount of
work done at the end of a given
period is no greater than if the
alcohol had not been given
at all.

Owing to the increased demand FlG; 82' circulation in the

Capillaries, as seen with

made on the wall of the heart the Microscope,
during the period of increased

activity, the heart itself is in a distinctly worse condition
than it would have been if the increased strain had
not been put upon it in consequence of the action of
the alcohol.

239. Further Effect of Alcohol upon the Circulation. The
inhibitory nerves, as we have seen, exercise a restraining
control orer the heart and the arteries, very much as the
reins control a running horse. In health this inhibitory
influence is protective and sustaining. When alcohol
is taken, these inhibitory nerves are partially paralyzed,
because the narcotic has had its effect upon that part of
the vaso-motor center which governs them.

158 Life and Health

The warm and flushed condition, or the " glow," of the
face which follows the social glass of alcoholic liquor is a
familiar illustration of this loss of inhibitory action. The
alcohol has caused a partial paralysis of that part of the
vaso-motor center which controls the arteries of the face.
In other words, they are no longer under perfect control,
and the blood is flushed into the blood vessels in greater
quantities. The dilatation of the superficial blood vessels
may become permanent, resulting in the red-streaked
appearance of the nose and face, so common with those
who habitually use strong drink.

240. Effect of Alcohol upon the Heart. This "whipping
up" of the heart, produced by the action of alcoholic liquors,
cuts short its periods of rest and after a time may cause
serious heart exhaustion. If the alcohol is repeated and
continued, it may involve grave changes of the structure of
the heart.

In still other cases the heart may suffer from what is
called fatty degeneration ; that is, minute particles of fat
are deposited in large amounts in its tissues in place of the
normal material.

241. Effect of Tobacco upon the Heart. The nicotine of
tobacco has a deadening effect upon the nerves that con-
trol the heart's action.1 The heart beats often become
irregular, feeble, and fluttering. Frequently there is dizzi-
ness, with short breath, palpitation on slight exertion,
extreme pallor, and fainting.

In this erratic condition of the pulse the physician may

1 Tobacco depends for its activity upon the presence of an alkaloid,
nicotine, a poison of such intensity that it has caused death in three
minutes. Even one thirty-second of a grain will cause serious symptoms.
Tobacco is a powerful depressant to the motor nerves. The sensory
nerves are probably also depressed. Nicotine has a very distinct influence
upon the circulation. — WOOD'S Therapeutics (Edition of 1901).

The Blood and its Circulation 159

read the existence of the " tobacco heart," an affection
recognized by all medical men. It is claimed that one in
every four of tobacco users is subject, in some degree, to
this disturbance. Test examinations of a large number
of young men who used cigarettes showed that only a very
small percentage escaped cardiac trouble.1

ADDITIONAL EXPERIMENTS

Experiment 67. To show how blood holds a mineral substance in
solution. Put an eggshell crushed fine into a glass of water made
acid by a teaspoonful of muriatic acid. After an hour or so the egg-
shell will disappear, having been dissolved in the acid water. In like
manner the blood holds various minerals in solution.

Experiment 68. To hear the sounds of the heart. Locate the
heart exactly. Note its beat. Borrow a stethoscope from some
physician. Listen to the heart beat of some friend. Note the sounds
of your own heart in the same way.

Experiment 69. To show how the pulse may be studied. The
movements of the artery in the human body as the pulse wave passes
through it may be shown to consist in a sudden dilatation, followed by
a slow contraction, interrupted by one or more secondary dilatations.
This demonstration may be made by pressing a small piece of looking-
glass about one centimeter square (two-fifths of an inch) upon the
wrist over the radial artery, in such a way that with each pulse beat
the mirror may be slightly tilted. If the wrist be now held in such a
position that sunlight will fall upon the mirror, a spot of light will be
reflected on the opposite side of the room, and its motion upon the
wall will show that the expansion of the artery is a sudden move-
ment, while the subsequent contraction is slow and interrupted. —
BOWDITCH'S Hints for Teachers of Physiology.

1 Tobacco, and especially cigarettes, being a depressant upon the heart,
should be positively forbidden. — DR. J. M. KEATING on "Physical
Development," in Cyclopedia of the Diseases of Children.

160 Life and Health

Experiment 70. Place on a glass slide a thin layer of defibrinated
blood (see Experiment 62); try to read printed matter through it.
This cannot be done.

Experiment 71. Wash away the coloring matter from the twigs
(see Experiment 62) with a stream of water until the fibrin becomes
quite white. It is fibrous and elastic. Stretch some of the fibers to
show their extensibility; on freeing them, they regain their elasticity.

Experiment 72. Take some of the serum saved from Experiment 62
and note that it does not coagulate spontaneously. Boil a little in a
test tube over a spirit lamp, and the albumen will coagulate.

Experiment 73. To illustrate some of the phenomena of cir-
culation. Take a common rubber bulb syringe, of any standard
make. Attach a piece of rubber tube about six or eight feet long to
the delivery end of the syringe.

To represent in a very crude way the resistance made by the
capillaries to the flow of blood, slip the large end of a common
glass medicine dropper into the outer end of the rubber tube. This
dropper has one end tapered to a fine point.

Place the syringe flat, without kinks or bends, on a desk or table
Press the bulb slowly and regularly. The water is thus pumped into
the tube in an intermittent manner, and yet it is forced out of the
tapering end of the glass tube in a steady flow.

Experiment 74. Take off the tapering glass tube, or, in the place
of one long piece of rubber tube, substitute several pieces of glass
tubing connected together by short pieces of rubber tubes. The
obstacle to the flow has thus been greatly lessened, and the water
flows out in intermittent jets to correspond to the compression of
the bulb.

Experiment 75. By injecting with a syringe warm liquid gelatin
(colored red) into the aorta of a dead animal, the whole vascular
system can be filled. The gelatin sets solid when it becomes cold,
and by cutting up the organs into thin slices and examining these
under the microscope, the network of blood vessels can be most
clearly observed. — HILL'S Manual of Human Physiology.

CHAPTER VIII
RESPIRATION

' 242. Nature and Object of Respiration. The blood, as
we have learned, not only provides material for the growth
and activity of all the tissues of the body, but also serves
as a means of removing from them certain waste products.

We have now to consider a new source of nourishment
to the blood, viz., that which it receives from the oxygen
of the air. We are also to learn one of the methods by
which the blood gets rid of poisonous waste matters.

We are to study the process of respiration, or the means
by which oxygen is supplied to the various tissues, and by which
the principal waste matters, or chief products of oxidation, are
removed from the tissues.

243. The Respiration of the Tissues. The tissues are
continually taking in oxygen and are continually producing
carbon dioxide and other waste products. In fact, the life
of the tissues is dependent upon a continual succession of
oxidations. When the blood leaves the tissues it is poorer
in oxygen, and is richer in carbon .dioxide. This exchange
of gases between the blood and the tissues is sometimes
spoken of as the respiration of the tissues, or internal respiration.

244. The Essential Step in Respiration. Now, as we
have seen, the capillaries of the lungs are the only means
of communication between the pulmonary arteries and the
pulmonary veins. The blood in the pulmonary capillaries
is separated from the air only by a delicate tissue formed

161

162

Life and Health

of its own wall and the pulmonary membrane. Hence a
gaseous interchange, the essential step in respiration, takes
place between the blood and the air, by which the latter
gains moisture and carbon dioxide, and loses its oxygen.
These changes in the lungs also restore to the dark blood
its bright red tint.

The only condition absolutely necessary to respiration
is an organ having a delicate membrane, on one side of
which is a thin sheet of blood, while the
other side is in such contact with the air
that an exchange of gases can readily
take place.

The demand for oxygen is, however,
so incessant, and the accumulation of
carbon dioxide is so rapid in every tis-
sue of the body, that an All-Wise Creator
has provided an extensive and compli-
cated accessory system of machinery to
effect this most remarkable and impor-
tant change in the blood.

Let us now study the arrangement
and working of this machinery, or, in
other words, the organs of respiration.

245. Passages from the Mouth. If we look into the
mouth of a friend, or into our own with the aid of a mirror,
we see at the back part an arch which is the boundary line
of the mouth proper. The funnel-shaped cavity beyond,
into which both the mouth and the posterior nasal pas-
sages open, is called the pharynx. In its lower part are
two openings : the trachea, or windpipe, in front, 'and the
cesophagus behind (Figs. 5 I and 45).

246. The Larynx and the Epiglottis. The trachea, or wind-
pipe, is surmounted by a box-like structure of cartilage, about

FIG. 83.
The Epiglottis.

Respiration

16

four and one-half inches long, called the larynx. It contains
the organ of voice and is more fully described in Chapter XII.

The upper end of the larynx opens into the pharynx, or
throat, and is provided with a kind of lid, — the epiglottis,
(sec. 156 and Fig. 45).

247, The Trachea, or
Windpipe. The continua-
tion of the larynx is the
trachea, a tube about three-
fourths of an inch in diam-
eter and about four inches
long. It extends down-
wards along the middle line
of the neck, where it may
readily be felt in front, be-
low the Adam's apple.

The walls of the wind-
pipe are strengthened by a
series of cartilaginous rings,
each somewhat the shape
of a horseshoe or like the
letter C, being incomplete
behind, where they come in
contact with the oesophagus.
Thus the trachea, while
always open for the passage

FIG. 84. Larynx, Trachea, and the
Bronchi. (Front view.)

of air, admits of the disten-
tion of the food passage.
>248. The Bronchial
Tubes. The lower end of
the windpipe divides into two branches called bronchi. Each
branch enters the lung of its own side and breaks up into
a great number of smaller branches called bronchial tubes.

, epiglottis ; B, thyroid cartilage ; C, crico-
thyroid membrane, connecting with the cri-
coid cartilage below, all forming the larynx;
D, one of the rings of the trachea.

164

Life and Health

These divide into smaller tubes, which continue subdividing

till the whole lung is penetrated by their minute branches.

The walls of the larger bronchial tubes would readily

collapse and close the passage for air, but for a wise

FIG. 85. Relative Position of the Lungs, Heart, and its Great Vessels.

A, left ventricle ; B, right ventricle; C, left auricle ; Z>, right auricle ; E, superior
vena cava ; F, pulmonary artery ; G, aorta ; //, arch of the~aorta ; fC, innomi-
nate artery ; L, right common carotid artery ; M, right subclavian artery ;
N, thyroid cartilage forming upper portion of the larynx ; O, trachea.

precaution. The horseshoe-shaped rings of cartilage in the
trachea and plates of cartilage in the bronchial tubes keep
these passages open.

•-! 249. The Cilia of the Air Passages. The inner surfaces
of the windpipe and bronchial tubes are lined with mucous
membrane, which serves to keep the parts moist.

Respiration

165

Delicate filaments, called cilia, not unlike the threads
which make up the pile on velvet, spring from the epithelial
lining of the air tubes. Their constant wavy movement
drives excessive secretion upwards towards the larynx,
where it is finally expelled by coughing. In this way the
lungs are also kept quite free from particles of foreign
matter derived from, the air. Thus
these tiny cilia act as dusters which
Nature uses to keep the air tubes
free and clean (sec. 23).
£- 250. General Structure of the
Lungs. The lungs, the chief organs
of respiration, are two pinkish-gray
structures of a light spongy appear-
ance that fill the chest cavity, except
the space taken up by the heart and
large vessels. Between the lungs
are situated the large bronchi, the
oesophagus, the heart in its pericar-
dium, and the great blood vessels.

The base of the lungs rests on the FIG. 86. Bronchial Tube,
dome-like diaphragm, which separates with its Divisions and
the chest from the abdomen. This Subdivisions-
partly muscular and partly tendinous (Show^ «rouPs of aij sacs

. . „ . a* the termination of mm-

partition is a most important factor ute bronchial tubes.)
in breathing.

-251*. The Pleura. Each lung is covered by an elastic
serous membrane in a double layer, called the pleura. One
layer closely envelops the lung, at the apex of which it
is reflected to the wall of the chest cavity of its own
side, which it lines. The two layers thus form between
them a closed sac, a serous cavity (see Fig. 70, also
sec. 2 1 3") . '

i66

Life and Health

In health the two pleural surfaces of the lungs are always
in contact, and they secrete just enough serous fluid to allow

the surfaces to
glide smoothly
upon each other.

252. Minute
Structure of the
Lungs. If one of
the smallest bron-
chial tubes be
traced in its tree-
like ramifications,
it will be found to
end in an irregular
funnel-shaped pas-
sage, wider than
itself. Around this

FIG. 87. The Lungs, with the Trachea, Bronchi,
and larger Bronchial Tubes exposed,
terior view.)

A, division of left bronchus to upper lobe ; £, left
branch of the pulmonary artery ; C, left bronchus ;
Z>, left superior pulmonary vein ; £, left inferior
pulmonary vein ; F, left auricle ; A", inferior vena
cava ; Z,, division of right bronchus to lower lobe ;
M} right inferior pulmonary vein ; IV, right supe-
rior pulmonary vein ; O, right branch of the pul-
monary artery ; P, division of right bronchus to
upper lobe ; R, left ventricle ; S, right ventricle.

(POS. passage is grouped
a number of cavities
with honeycomb-
like walls, the air
cells,1 or air sacs, of
the lungs. These
communicate freely
with the passage,

and through it with
the bronchial branches, but have no other openings.* The
whole arrangement of passages and air sacs springing from
the end of a bronchial tube is called an ultimate lobule.

1 The word " cell " is not used in this connection in its technical signifi-
cation of a histological unit of the body (sec. 16), but merely in its primary
sense of a small cavity. It is better, however, to call these cavities "air

Resp iration 167

Countless numbers of these lobules, bound together by
connective tissue, are grouped after the same fashion to
form by their aggregation the lobes of the lung. The right
lung has three such lobes, and the left, two.

The walls of the air sacs are of extreme thinness, con-
sisting of delicate elastic and connective tissue, and lined
inside by a single layer of thin epithelial cells. In the con-
nective tissue run capillary vessels belonging to the pul-
monary artery and veins. Now these delicate vessels are

FIG. 88.

A, diagrammatic representation of the ending of a bronchial tube in air sacs, or alveoli ;

B, termination of two bronchial tubes in enlargement beset with air sacs (Huxley);

C, diagrammatic view of an air sac. A lies within sac and points to epithelium
lining wall; B, partition between two adjacent sacs, in which run capillaries;
c, elastic connective tissue (Huxley).

surrounded on all sides by air sacs. It is evident, then,
that the blood flowing through these capillaries is sepa-
rated from the air within the sacs only by the thin walls of
the vessels and the delicate tissues of the air sacs (Fig. 90).

This arrangement is perfectly adapted for an interchange
between the blood in the capillaries and the air in the air
sacs. This will be more fully explained in sec. 260.

253. Inspiration and Expiration. The act of breathing
consists of a series of rhythmical movements, succeeding
one another in regular order. In the first movement the

1 68 Life and Health

chest expands, and there is an inrush of fresh air. This is
known as inspiration.

This is at once followed by the falling of the chest walls
and the expulsion of air. This is known as expiration.

A pause now occurs, and the same breathing movements
are repeated.

254. The Number of Respirations. In a healthy adult
the number of respirations should be from 16 to 18 per
minute. Exercise increases the number, while rest dimin-
ishes it. In standing the rate is more than when lying at
rest. Mental excitement quickens the rate. The rate is
lowest during sleep.

In diseases involving the lungs, bronchial tubes, and the
pleura, the rate may be alarmingly increased, and the pulse
is quickened in proportion.

The entrance and the exit of air into the respiratory
passages are accompanied with peculiar sounds, which are
readily heard on placing the ear at the chest wall.
^255. The' Chest as an Air-Tight Chamber. The chest is
an air-tight chamber with movable walls and floor. It has
bony walls, with ribs connecting in front with the breast-
bone and behind with the spine. The spaces between the
ribs are occupied by the intercostal muscles, while large
muscles clothe the entire chest. The diaphragm serves as
a movable floor to the chest.

In this air chamber are suspended the lungs, the air cells
of which communicate with the outside through the bron-
chial passages, but have no connection with the chest cavity.
The thin space between the lungs and the walls of the
chest, called the pleural cavity, is in health a vacuum.

256. The Mechanism of Normal Respiration. Let us
now study the chief points about the mechanism of breathing,
or respiration.

Respiration

169

When the diaphragm contracts it descends and thus
increases the depth of the chest cavity. Being elastic,
the lungs expand, filling up the increased space, and a
quantity of air is drawn into them. As soon as the dia-
phragm relaxes, returning to its arched position and redu-
cing the size of the chest cavity, the
lungs diminish in size and the air is
driven out. After a short pause the
diaphragm again contracts, and the
same round of operations is repeated.

By the contractions of the inter-
costals and other muscles the ribs
are raised and the breastbone pushed
forward. The chest cavity is thus
enlarged from side to side and from
behind forwards. Thus, by the simul-
taneous descent of the diaphragm and
the elevation of the ribs, the cavity
of the chest is enlarged in three direc-
tions, — downwards, sideways, and
from behind forwards.
X It is thus evident that inspiration is
due to a series of muscular contractions.

When the contractions cease the
walls of the chest resume their former
position and the diaphragm ascends.
As a result of these movements, the
original size of the chest cavity is
restored, and the inhaled air is driven from the lungs.
^Expiration may then be regarded as the result of an
elastic recoil, and not of active muscular contractions.
/ 257. The Nervous Control of Respiration. The move-
ments of breathing go on without our attention. In sleep

FIG. 89. Diagrammatic
Section of the Trunk.

(Showing the expansion of
the chest and the move-
ment of the ribs. The
dotted lines indicate the
position during inspira-
tion.)

1 70 Life and Health

the regularity of respiration is even greater than when we
are awake. There is a particular part of the nervous sys-
tem that presides over the breathing function. It is situ-
ated in that part of the brain called the medulla oblongata
and is fancifully called the "vital knot" (sec. 330). It is
injury to this respiratory center which usually proves fatal
in cases of broken neck.

From this nerve center there is sent out to the nerves
that supply the diaphragm and other muscles of breathing
a force which stimulates them to regular contraction. This
breathing center is modified by the condition of the blood.
It is stimulated by an excess of carbon dioxide in the blood
and is quieted by the presence of oxygen.

Experiment 76. To locate the lungs. Mark out the boundaries of
the lungs by "sounding" them ; that is, by percussion, as it is called.
This means to put the forefinger of the left hand across the chest or
back and to give it a quick, sharp rap with two fingers of the right
hand. Note where it sounds hollow or resonant.

Experiment 77. Borrow a stethoscope and listen to the respiration
over the chest. This is known as auscultation. Note the difference
of the sounds in inspiration and in expiration. Do not confuse the
heart sounds with those of respiration. The respiratory sounds are
better heard on the right side. They may be heard fairly well by
applying the ear flat to the chest, with only one garment interposed.

Experiment 78, Get a sheep's lungs, with the windpipe attached.
Ask for the heart and lungs all in one mass. Take pains to examine
the specimen first and accept only a good one. Parts are apt to
be hastily snipped or mangled. Examine the windpipe. Note the
horseshoe-shaped rings of cartilage in front, which serve to keep
it open.

Experiment 79. Examine one bronchus, carefully dissecting away
the lung tissue with curved scissors. Follow along until small branches
of the bronchial tubes are reached. Take time for the dissection and
save the specimen in dilute alcohol. Put pieces of the lung tissue
in a basin of water and note that they float

Respiration 1 7 1

••

258. The Gases of the Blood. The blood contains three
gases, partly dissolved in it and partly in chemical union
with certain of its constituents. These are oxygen, carbon
dioxide, and nitrogen. The nitrogen need not be taken into
account.

The oxygen is the material which the tissues require to
carry on their work.

The carbon dioxide is a waste substance which the tissues
produce by their activity, and which the blood carries away
from them.

^ 259. Effects of Respiration upon the Blood. As we have
learned in a previous chapter, the arterial blood loses part of
its oxygen in the tissues, and carbon dioxide takes its place.
Now if the blood is to maintain its efficiency in this respect,
it must always be receiving new supplies of oxygen, and
also have some mode of throwing off its excess of carbon
dioxide. This, then, is the double functign of respiration.

Again, the blood sent out from the left side of the heart
is of a bright scarlet color. After the blood has passed
through the tissues and returns to the right side of the
heart, it is of a more purple or claret color. This change
in color takes place in the systemic capillaries and is due
to the fact that there the blood gives up most of its oxygen
to the tissues and receives from them a great deal of carbon
dioxide.

In brief, while passing through the capillaries of the
lungs the blood is changed from the venous to the arterial
condition. That is to say, the blood in its progress through
the lungs rids itself of its excess of carbon dioxide and obtains
a fresh supply of oxygen.1

1 The student must guard himself against the idea that arterial blood
contains no carbonic acid, and venous blood no oxygen. In passing through
the lungs venous blood loses only a part of its carbonic acid; and arterial

172 Life and Health

260. Effects of Respiration upon the Air in the Lungs.
It is well known that if two different liquids be placed in
a vessel in contact with each other and left undisturbed,
they do not remain separate, but gradually mix, and in
time will be perfectly combined. This is called diffusion
of liquids.

Diffusion occurs with gases also, though the process
is not usually visible. Two liquids will mingle even when
separated from each other by a membrane. In a simi-
lar manner two gases, especially if of different densities,
may mingle even when separated from each other by a
membrane.

In a general way this explains the respiratory changes
that occur in the blood in the lungs. Blood containing
oxygen and carbon dioxide is flowing in countless tiny
capillaries through the walls of the air sacs of the lungs.
The air sacs themselves contain a mixture of the same two
gases. A thin, moist membrane, well adapted to allow
gaseous diffusion, separates the blood from the air. This
membrane is the delicate wall of the capillaries and the
epithejhmi of the air sacs.

By experiment it has been found that the pressure of
oxygen in the blood is less than that in the air sacs, and
that the pressure of carbon dioxide gas in the blood is
greater than that in the air sacs. A diffusion of gases ensues.

The results of respiration upon the air in the lungs are
thus twofold :

The blood gains oxygen and loses carbon dioxide.

The air sacs lose oxygen and gain carbon dioxide.

blood, in passing through the tissues, loses only a part of its oxygen. In
blood, however venous, there is in health always some oxygen ; and in
even the brightest arterial blood there is actually more carbonic acid than
oxygen. — T. H. HUXLEY.

Respiration

173

261. The Changes of Air in Breathing. The air which we
exhale during respiration differs in several important particulars
from the air we inhale. Expired air contains about 5 per
cent less oxygen and 5 per cent more carbon dioxide than
inspired air.

The temperature of expired air is usually higher than that
of inspired air ; it is also loaded with aqueous vapor, imparted
to it in the upper air passages. The average daily quantity of
water exhaled as vapor is about one-half pint.

The quantity of oxygen removed from the air by the breath-
ing of an adult person at rest amounts daily to about eighteen
cubic feet. About the same
amount of carbon dioxide is
expelled.

Expired air contains,
besides carbon dioxide, a
small amount of poisonous
organic matter, which, from
the presence of micro-
organisms, introduced in the
inspired air, is apt to putrefy
rapidly.

Various animal sub-
stances give rise, by de-
composition, to distinct
poisonous products known
as ptomaines.

It is possible that some
of the constituents of the
expired air are of an allied
nature. At all events, these
substances have an injuri-
ous action, for an atmos-
phere containing simply i per cent of pure carbon dioxide has
very little harmful effect on the animal economy, but an atmos-
phere in which the carbon dioxide has been raised even half
of i per cent by breathing is highly injurious.

NOTE. — The nature, propagation, and action of bacteria are
described in more detail under the topic of " Bacteria," in Chapter
XIII of this book.

FIG. 90. Capillary Network of the

Air Sacs and Origin of the

Pulmonary Veins.

A, small branch of pulmonary artery ; B, twigs
of pulmonary artery anastomosing to form
peripheral network of the primitive air cells ;
C, capillary network around the walls of the
air sacs ; D, branches of network converg-
ing to form the veinlets of the pulmonary
veins.

1 74 Life and Health

262. Modified Respiratory Movements. Certain modi-
fied respiratory movements need explanation.

Coughing is usually produced by irritation in the upper part
of the windpipe and larynx. A deep breath is drawn, the
opening of the windpipe is closed and immediately is burst
open with a violent effort, which sends a blast of air through
the upper air passages. The object is to expel any mucus
or foreign matter that is irritating the air passages.

Sneezing is like coughing ; the tongue is raised against the
soft palate, so that the air is forced through the nasal pas-
sages. It is caused by an irritation of the nostrils or eyes.

Sighing is a rapid and generally audible expiration, due
to the elastic recoil of the lungs and chest walls. It is
often caused by depressing emotions. Yawning is a deep
inspiration with a stretching of the muscles of the face.
It is usually excited by fatigue or drowsiness.

Laughing consists of a series of short, rapid, spasmodic
expirations, which cause the peculiar sounds, with char-
acteristic movements of the facial muscles. Crying, caused
by emotional states, consists of sudden jerky expirations,
with long inspirations, and facial movements indicative
of distress. In sobbing, which often follows long-continued
crying, there is a rapid series of convulsive inspirations,
with sudden involuntary contractions of the diaphragm.

Hiccough is a sudden jerking inspiration due to the spas-
modic contraction of the diaphragm and of the vocal cords,
causing the air to rush suddenly through the larynx and
produce this peculiar sound.

X263. How the Atmosphere is made Impure. The air
around us is constantly being made impure in a great
variety of ways. The combustion of fuel, the respiration
of men and animals, the exhalations from their bodies, the
noxious gases and effluvia of the various industries, together

Respiration

175

with the changes of fermentation and decomposition to
which all organized matter is liable, — all tend to pollute
the atmosphere.

The breathing of dust and smoke in the air of towns,
which is to a greater or less extent laden with the germs of
disease, is an ever-present and most potent menace to public
and personal health. It is one of the main causes of the
excess of mortality in towns and cities over that of country
districts.

. This is best shown in the overcrowded streets and houses
of great cities, which are deprived of the purifying influence
of sun and air. The fatal effect of living in vitiated air is
especially marked in the mortality among infants and chil-
dren living in the squalid and overcrowded sections of our
great cities.

Experiment 80. Simple apparatus to illustrate the movements of
the lungs in the chest. T is a bottle from which the bottom has been
removed ; Z>, a flexible and elastic mem-
brane tied on the bottle and capable
of being pulled out by the string -5", so
as to increase the capacity of the bottle.
L is a thin elastic bag representing the
lungs. It communicates with the exter-
nal air by a glass tube fitted air-tight
through a cork in the neck of the bottle.
When D is drawn down the pressure of
the external air causes L to expand.
When the string is let go L contracts
again by virtue of its elasticity. FIG. 91.

- 264. The Necessity for a Proper Supply of Pure Air ; the
Need of the Removal of Impure Air. As we have learned,
the expired air contains, besides carbon dioxide, not only
a certain amount of organic matter in the form of vapor,
but minute dust particles including many micro-organisms.

1 76 Life and Health

The air thus already vitiated putrefies very rapidly after
it leaves the mouth. It is at once absorbed by clothing,
curtains, carpets, porous walls, and by many other objects.
It is difficult to dislodge these enemies of health even by
free ventilation. The close and disagreeable odor of a
filthy or overcrowded room is due to these organic exhala-
tions from the lungs and the skin, as well as from the
unclean clothing of the occupants.

The necessity of having a proper supply of fresh air in
enclosed places, and the need of removal of impure air are
thus evident. If a man were shut up in a tightly sealed
room containing 425 cubic feet of air, he would be found
dead, or nearly so, at the end of twenty-four hours. Long
before this time he would have suffered from nausea, head-
ache, dizziness, and other proofs of poisoning. These
symptoms are often felt by those who are confined for an
hour or more in a room where the atmosphere has been
polluted by a crowd of people. The unpleasant effects
may rapidly disappear on breathing fresh air.

-265. The Effect on the Health of breathing Foul Air.
People are often compelled to remain indoors for many
hours, day after day, in shops, factories, or offices, breath-
ing air perhaps only slightly vitiated, but still recognized
as "stuffy." Such persons often suffer from loss of appe-
tite, dull headache, fretfulness, persistent weariness, and
general weakness.

Persons in this lowered state of health are much more
prone to suffer from colds, catarrhs, bronchitis, and pneu-
monia than if they were living in the open air, or breathing
only pure air. Thus, in military service, the soldiers who
live in tents in the coldest weather are far more free from
colds and lung troubles than those who live in tight and
ill-ventilated huts.

Respiration

177

266. The Danger from Pulmonary Infection. The germ
of pulmonary consumption, known as the bacillus tuberculosis,
is contained in the breath and the sputa from the lungs
of its victims. It is not difficult to understand how these
bacilli may be conveyed through the air from the lungs of
the sick to those of apparently healthy people. Such per-
sons may, however,
be predisposed,
either constitution-
ally or by defective
hygienic surround-
ings, to fall victims
to this dread disease.
Overcrowding, poor
ventilation, and
dampness all tend to
increase the risk of
pulmonary infection.

These bacilli are
not necessarily
transmitted directly
through the air from
the lungs of the sick
to be implanted in
the lungs of the
healthy. They may
remain for a time in -the dust of damp, filthy, and over-
crowded houses. The dust contains the germs, and thus
they may enter the body with the air breathed. In a
congenial soil the bacilli retain their vitality for a long
time, and possibly may take on more virulent infective
properties than they possessed when expelled from the
diseased lungs.

FIG. 92. Bacillus Tuberculosis.

(A minute portion of sputum from a case of phthisis,
or " consumption " of the lungs, magnified by
1000 diameters. These bacilli are rod-shaped
bacteria, stained to show black. The black spots
in the figure are merely the debris in the spu-
tum, also stained to show black.)

178 Life and Health

267. The Object of Ventilation. The question of a prac-
ticable and economical system of ventilation for our homes,
schoolrooms, workshops, and public places presents many
difficult and perplexing problems. It is perhaps due to the
complex nature of the subject that ventilation, as an ordi-
nary condition of daily health, has been so much neglected.
The matter is practically ignored in building ordinary houses.
The continuous renewal of air receives little, if any, consid-
eration, compared with the provision made to furnish our
homes with heat, light, and water.

The object of ventilation should be twofold : first, to
provide for the removal of the impure air ; second} to provide
for a supply of pure air without cold draughts. This is one of
the most difficult of sanitary problems.

ANIMAL HEAT

v

268. Animal or Vital Heat. If a thermometer, made for
the purpose, be placed for five minutes in the armpit . or
under the tongue, it will indicate a temperature of about
98^-° Fahr., whether the surrounding atmosphere be warm
or cold. This is the normal temperature of a person in
health, and it rarely varies more than a degree or two.
Now, as the body is constantly losing heat by radiation and
conduction, it is evident that if the normal temperature
be maintained, a certain amount of heat must be generated
within the body to make up for this 'loss.

The heat thus produced is known as animal or vital heat.

269. Sources of Bodily Heat. The heat of the body is
generated by the chemical changes which are constantly
going on in the tissues. These chemical changes are of
various kinds, but the great source of heat is the katabolic
process known as oxidation.

Respiration 1 79

Wherever there is life, this process of oxidation is going
on, but more energetically in some tissues and organs than
in others. In other words, every tissue in the body is a source
of heat in proportion to the activity of its chemical changes.
The more active the changes, the greater is the heat pro-
duced, and the greater the amount of urea, carbon dioxide,
and water eliminated.

The waste caused by this oxidation must be made good
by a due supply of food to be built up into protoplasmic
material. For the production of heat, therefore, food is
necessary. The oxidation process is not so simple and
direct as the statement of it might seem to indicate ;
but the ultimate result is as simple as in ordinary com-
bustion outside of the body, and the products are the
same.

The continual chemical changes, then, chiefly by oxida-
tion of combustible materials in the tissues, produce an
amount of heat which is sufficient to maintain the tem-
perature 6f the living body at about 98^-° Fahr. This
process of oxidation provides not only for the heat, but
also for the mechanical energy, required to carry on the
work of the body.

270, Regulation of the Bodily Temperature. While bodily
heat is being continually produced, it is also as continually
being lost by the lungs, by the skin, and to some extent
by certain excretions. The blood, in its swiftly flowing
current, carries warmth from the tissues where heat is
being rapidly generated, to the tissues or organs in which
it is being lost by radiation, conduction, or evaporation.
Were there no arrangement by which heat could be dis-
tributed and regulated, the temperature of the body would
be very unequal in different parts and would vary at
different times.

180 Life and Health

The normal temperature is maintained with slight varia-
tions throughout life. Indeed, a change of more than a
degree above or below the average indicates some disease
in the organism or some unusual influence. It is evident,
then, that the mechanisms which regulate the temperature
of the body must be exceedingly sensitive.

The two chief means of regulating the temperature of
the body are the lungs and the skin.

Experiment 81. To show the natural temperature of the body.
Borrow a physician's clinical thermometer, and take your own tem-
perature, and that of several friends, by placing the instrument under
the tongue, closing the mouth, and holding it there for five minutes.
Read it while in position, or the instant the. instrument is removed.
The natural temperature is about 98^° Fahr. The thermometer
should be thoroughly cleansed after each use.

If a doctor's thermometer is not to be obtained, unfasten and use
one of the little thermometers often found on calendars and adver-
tising circulars. The bodily temperature will not be indicated accu-
rately in this crude way.

NOTE. — A substitute for a clinical thermometer may be readily
contrived by taking an ordinary house thermometer from its tin case
and cutting off the lower part of the scale so that the bulb may pro-
ject freely. With this instrument the pupils may take their own and
each other's temperatures, and it will be found that, whatever the
season of the year or the temperature of the room, the thermometer
in the mouth will record about 99° Fahr. Care must, of course, be
taken to keep the thermometer in the mouth till it ceases to rise, and
to read while it is still in position. — PROFESSOR H. P. KOWDITCH.

271. The Skin as a Heat Regulator. The great regulator
of the bodily temperature is the skin.

First, the skin regulates the loss of heat by means of
the vaso-motor mechanism. The greater the quantity of
blood which passes through the skin, the greater will be
the loss of heat by conduction, radiation, and evaporation.

Resp iration 1 8 1

Hence any action of the vaso-motor mechanism which
causes dilatation of the cutaneous capillaries leads to a
larger flow of blood through the skin and will tend to cool
the body. On the other hand, when by the same mechan-
ism the cutaneous vessels are constricted there will be a
smaller flow of blood through the skin, which will serve to
check the loss of heat from the body.

Again, the special nerves of perspiration act directly as
regulators of temperature. They increase the loss of heat
when they promote the secretion of the skin, and diminish
the loss when they cease to promote it.

272. How the Bodily Temperature is adjusted during
Exercise. The practical working of this heat-regulating
mechanism is well shown when we take exercise. The
bodily temperature rarely rises as much as a degree dur-
ing vigorous exercise. The respiration is increased, the
cutaneous capillaries become dilated from the quickened
circulation, and a larger amount of blood circulates through
the skin. The presence in the skin of so much blood stim-
ulates the sweat glands to increased activity, resulting in
a free perspiration. A large amount of heat is thus lost
to the body, sufficient to offset the addition caused by the
muscular contractions.

This topic is again treated in the description of the skin
as a regulator of the bodily temperature (sec. 291).

273. Effect of Alcohol upon the Respiration. Alcohol
tends to diminish the breathing capacity of the lungs.
This effect follows from its partial paralyzing influence
upon the sympathetic nervous system.

The enfeebled respiration explains (though it is only one
of the reasons) why habitual users of alcoholic liquors can-
not endure a normal amount of vigorous and prolonged
exertion. The hurried circulation produced by intoxicants

182 Life and Health

involves in turn quickened respiration, which means more
rapid exhaustion of the life forces.

The prolonged use of alcohol also involves a repeated
dilatation of the capillaries, which steadily diminishes their
distensive power, thereby rendering the person more sus-.
ceptible to the attack of pulmonary diseases.

274. Effect of Alcohol upon Pulmonary Diseases. The
habitual use of alcoholic liquors, it is believed, makes a
person unusually susceptible to pneumonia.

It has also been found that pulmonary tuberculosis is
more frequent in drinkers than in ordinary people. A noted
physician of Paris (M. Legendre) says : " Alcohol is a fre-
quent cause of consumption by its power of weakening the
lungs." 1

The persistent user of alcohol also suffers, more severely
than abstainers, from other and less dangerous pulmonary
diseases, as simple colds, chronic bronchitis, and influenza.

275. Effect of Tobacco upon the Respiratory Passages.
The effects of tobacco upon the throat and lungs are
frequently marked and persistent. The smoke irritates
the mucous membrane of the mouth and throat, producing
an unnatural thirst. The inflammation may extend up the
Eustachian tube, and impair the sense of hearing.

The inhalation of tobacco smoke often produces unhealth-
ful effects upon the delicate mucous membrane of the bron-
chial tubes and of the lungs. This results frequently in
an irritating cough, with short breath.2

1 Alcohol, instead of preventing consumption, reduces the vitality so
much as to render the system unusually susceptible to that fatal disease. —
DR. R. S. TRACY, Sanitary Inspector, New York Health Department.

2 The action of the heart and lungs is impaired by the influence of the
narcotic on the nervous system, but a morbid state of the larynx, trachea,
and lungs results from the direct action of the smoke. — DR. LAYCOCK,
Professor of Medicine in the University of Edinburgh.

Respiration

ADDITIONAL EXPERIMENTS

Experiment 82. To show how the lungs may be filled with air.
Take one of the lungs saved from Experiment 78. Tie a glass tube
six inches long into the larynx. Attach a piece of rubber to one end
of the glass tube. Now inflate the lungs several A

times and let them collapse.

Experiment 83. To show that the expired air
contains carbon dioxide. Put a glass tube into a
bottle of lime water and blow through the tube.
The liquid will soon become cloudy, because the
carbon dioxide of the expired air unites with the
lime held in solution and forms the white, solid
carbonate of lime.

Experiment 84. To illustrate the manner in
which the movements of inspiration cause the air
to enter the lungs. Fit up an apparatus, as repre-
sented in Fig. 93, in which a stout glass tube is
provided with a sound cork, B, and also an air-
tight piston, D, resembling that of an. ordinary
syringe. A short tube, A, passing through the
cork, has a small India-rubber bag, C, tied to it.
Fit the cork in the tube while the piston is near
the top. Now, by lowering the piston, we increase
the capacity of the cavity containing the bag. The
pressure outside the bag is thus lowered, and air
rushes into it through the tube, A, till a balance
is restored. The bag is thus stretched. As soon
as we push up the piston, the elasticity of the bag,
being free to act, drives out the air just taken in,
and the piston returns to its former place.

In this experiment the elastic bag and its tube
represent the lungs and trachea, and the glass vessel enclosing it rep-
resents the thorax. It must be remembered, however, that the space
between the wall of the thorax and the outside of the lung is a vacuum.

FIG. 93.

Apparatus for

illustrating the

Movements of

Respiration.

CHAPTER IX
THE SKIN AND THE KIDNEYS

-J 276. The Formation of Waste Products. We have learned
that the food materials, prepared by the digestive processes,
are taken up by the branches of the portal vein, or by the
lymphatics, and carried to the tissues to provide them with
nourishment.

We have learned also that oxygen, introduced into the
body by the lungs, is being continually carried to the tissues,
and that the blood is constantly being purified by being
deprived in the lungs of its excess of carbon dioxide.

From this tissue activity, which is mainly a process of
oxidation, are formed certain waste products which, as we
have seen, are carbon dioxide, water, and urea, or some
closely allied body.

Remember, then, that carbon dioxide, urea, salts, and water
are the chief waste products of the body, and that they are cast
out of the body by three main channels, — the lungs, the
skin, and the kidneys.

A 277. How the Waste Products are eliminated. The elimi-
nation of these waste products is brought about by a special
apparatus called the organs of excretion. The worn-out sub-
stances themselves are called excretions, as opposed to secretions,
which are elaborated for use in the body (see note, p. 99).

As already shown, the lungs are the main channels for
the elimination of carbon dioxide. They also excrete a con-
siderable quantity of water as vapor.

184

The Skin and the Kidneys

185

By the skin the body gets rid of a small quantity of salts,
a little carbon dioxide, and a large amount of water in the form
of perspiration.

From the kidneys are eliminated nearly all the urea and
allied bodies, most of the salts, and a large amount of
water. Practically all the nitrogenous waste products leave
the body by the kidneys.

278. The Skin as an Important and Complex Organ.
The skin is a blood-purifying organ as truly as are the lungs
and the kidneys, while it per- ,

forms other and complex duties.
It also serves as a protective
covering for the surface of the
body.

The skin, being richly sup-
plied with nerves, is an impor-
tant organ of sensibility and
touch (sec. 370).

The skin ranks as an impor-
tant organ of excretion, its prod-
uct being the sweat.

The skin also plays an im-
portant part in regulating the
bodily temperature (sec. 271).

279. General Structure of the
Skin. The skin is divided into
two distinct layers, which may

be readily separated : the deeper layer, — the true skin,
dermis, or corium ; and the superficial layer, or outer skin, —
the epidermis, cuticle, or scarf skin. In some parts of the
body the skin is closely attached to the structures beneath,
while in others it is less firmly adherent and rests upon a
variable amount of fatty tissue. It thus assists in relieving

FIG. 94. Diagrammatic Scheme
to illustrate in a very General
Way Absorption and Excre-
tion.

A, represents the alimentary canal;
Z,, the pulmonary surface ; K, the
surface of the renal epithelium;
S, the skin ; a, oxygen ; A, hydro-
gen ; «, nitrogen.

1 86 Life and Health

the abrupt projections and depressions of the general surface,
and in giving roundness and symmetry to the entire body.
The thickness of the skin varies in different parts of the
body. Where exposed to pressure and friction, as on the

soles of the feet and in
the palms of the hands, it
is much thickened.

The true skin is ^ to \
of an inch in thickness, but
in certain parts, as in the
FIG. 95. A Layer of the Cuticle from lips and ear passages, it is

the Palm of the Hand. (Detached often not more than i of
by maceration.) ... . -1 ° .

an inch thick. At the ori-
fices of the body, as at the mouth, ears, and nose, the skin
gradually passes into mucous membrane, the structure of
the two being practically identical.

280. The Cutis Vera, or True Skin. The true skin con-
sists of elastic and white fibrous tissue, the bundles of
which interlace in every direction. Throughout this felt-
work structure are numerous muscular fibers, as about the
hair follicles and the oil glands. When these tiny muscles
contract from cold or emotion, the little hairs project upon
the surface, producing what is called " goose flesh."

The true skin is richly supplied with blood vessels and
nerves, as shown by the fact that it bleeds freely when
cut and that it is very sensitive. The surface of the true
skin is thrown into a series of minute elevations, called
the papillae, upon which the outer skin is moulded. These
abound in blood vessels, lymphatics, and peculiar nerve
endings, which will be described in connection with the
organ of touch (sec. 371 and Fig. 104).

The papillae are large and numerous in sensitive places,
as the palms of the hands, the soles of the feet, and the

The Skin and the Kidneys

fingers. They are arranged in paral-
lel curved lines, and form the elevated
ridges seen on the surf ace. of the outer
skin (Figs. 97 and 98).
^^> 281. The Epidermis, or Cuticle.
Above the true skin is the epidermis,
which as seen under the microscope
resembles the scales of a fish. It is
this layer that is raised by a blister.

As the epidermis has neither blood
vessels nor lymphatics, it may be
cut without bleeding. It contains no
nerves except in the deepest layers,
therefore the surface is not sensitive
to pain. The cuticle is made up of
several layers of cells, which next to
the true skin are soft and active, but
gradually become harder towards the
surface, where they are flattened and
scale-like.

The upper scales are continually
being rubbed off and are replaced by
deeper cells from beneath. These
new cells continually push upward the
cells already existing, then gradually
become dry and are cast off as fine
white dust.

Rubbing with a coarse towel after
a hot bath removes countless numbers
of these dead cells. During and after
an attack of scarlet fever the patient
"peels," that is, sheds an unusual
amount of the scaly cells of the cuticle.

FIG. 96. Cross-Section
of Skin, with Blood
Vessels injected.

(Magnified 30 diameters.)

A, horny layer of cuticle ;
&, deeper layer of cuticle,
rete mucosum ; C, duct of
sweat gland; D, corium,
or true skin ; JE, subcutis,
or sub-layer of corium,
with columnar epidermic
cells in immediate contact
with dermis. (The blood
vessels are injected and in
this figure show black.)

1 88

Life and Health

282. What gives the Skin its Color. The deeper and
more active layer of the epidermis, the rete mucosum, is
made up of pigment cells, some of which contain minute
granules of coloring matter that give color to the skin.
The differences in the tint, as brunette, fair, and blond,
are due mainly to the amount of coloring matter in these
pigment cells. In the European this amount is generally

small, while in other peoples
the color cells may be brown,
}. ,_, ,...„- yellow, or even black.

Experiment 85. Of
course the living skin
can be examined only in
a general way. Stretch
and pull it, and notice
that it is elastic. Note
any liver spots, white
scars, moles, warts, etc.
Examine the outer skin
carefully with a strong magnifying glass. Study the papillae on
the palms. Scrape off with a blunt knife a few bits of the scarf
skin, and examine them with the microscope.

283. Structure of the Hair. The hair and the nails are
modified forms of the epidermis.

A hair is formed in a depression, or furrow, the inner
walls of which consist of the infolded outer skin. This
'depression takes the form of a sac and is called the hair
follicle, in which the roots of the hair are embedded.

Opening into each hair follicle are usually one or more
sebaceous, or oil glands, producing an oily secretion which
serves to oil the hair and keep the skin moist and
pliant (Fig. 100).

At the bottom of the follicle there is an upward projec-
tion of the true skin, a papilla, which contains blood vessels

FIG. 97. Surface of the Palm of the Hand,
showing the Openings of the Sweat Glands
and the Grooves between the Papillae of
the Skin.

(In the smaller figure the same epidermal surface
is shown as seen with the naked eye. Magni-
fied 4 diameters.)

The Skin and the Kidneys

189

and nerves. It is covered with epidermic cells which mul-
tiply rapidly, thus causing the rapid growth of the hair.

Surmounting each papilla is a bulbous expansion, the hair
tyilb, from which the. hair begins to grow.

n vr° 284. How the Hair grows. The cells on the papillae form
the hairs. As these cells are pushed upwards by new ones
formed beneath, they are compressed, and the shape of the
follicle determines the cylindrical form of the shaft of the
hair. So closely are these cells welded to form the cylin-
der that even under a microscope the hair presents only a
fibrous appearance, except in the center, where the cells
are larger, forming the medulla, or pith (Fig. 107).

(LjT 285. What gives the Color to the Hair. The medulla of
the hair contains the pigment granules, or coloring matter,
which may be of any shade between a light yellow and an
intense black. It is this that gives
the great variety in color. Generally
with old people the pigment is absent,
the cells being occupied by air ; hence
the hair becomes gray or white.
\l 286. The Nails. A nail is simply
a thick layer of epidermic cells or
horny scales built from the outer part
of the scarf skin. It lies upon very
fine and closely set papillae, forming
its matrix, or bed. It is covered at its
base with a fold of the true skin, called

, . . ' . . . (It will be noticed that there

its root, from beneath which it seems are only a few orifices Of

to grow (Figs. 10 1, 102, and 108)..

J 287. Structure of the Sweat Glands.

Deep in the substance of the true

skin, or in the fatty tissue beneath it, are the sweat glands.

Each gland consists of a single tube with a blind end, coiled

FIG. 98. Epidermis
of the Foot.

the sweat glands in this
region. Magnified 8
diameters.)

190 Life and Health

in a sort of ball about one-sixtieth of an inch in diameter.
From this coil the tube passes upward through the dermis
in a wavy course until it reaches the cuticle, which it pene-
trates with a number of spiral turns, at last opening on the
surface.

The tubes have delicate walls lined with epithelial cells.
The coil of the gland is enveloped by minute blood vessels.

FIG. 99. Cross-Section of a Human Hair with its Follicle.
(Magnified about 300 diameters.)

The cells of the glands are separated from the blood only
by a fine partition and draw from it whatever supplies they
need for their special work.

^ 288. Number of Sweat Glands. With few exceptions
every portion of the skin is provided with sweat glands,
but they are not equally distributed over the body. They

The Skin and the Kidneys

191

are fewest in the back and neck, where it is estimated they
average 400 to the square inch. They are thickest in the
palms of the hands, where they amount to nearly 3000 to
each square inch. These minute open-
ings occur in the ridges of the skin and
may be easily seen with a hand lens.
The length of a tube when straight-
ened is about one-fourth of an inch. The
total number in the body is roughly esti-
mated at about 2,500,000, thus making
about ten miles of sweat tubes.
j 289. The Composition and Quantity of
Sweat. The sweat is a turbid, saltish fluid
with a feeble but characteristic odor due
to certain volatile fatty acids. Of the
inorganic constituents of sweat, common
salt is the largest and most important.
Some carbon dioxide passes out through
the skin, but not more than one-fiftieth
as much as escapes by the lungs.

The sweat ordinarily evaporates from
the pores into the air as fast as it is
formed. This is called insensible perspira-
tion. About a pint of sweat is thus lost
in the course of a day.

If there is no perspiration visible we
must not infer that the skin is inactive,
since sweat is continually passing from
the surface.

^ 290. The Visible Sweat. The visible sweat, frequently
spoken of as sensible perspiration, becomes abundant dur-
ing active exercise, after copious drinking of cold water, on
taking certain drugs, and when the body is exposed to

FIG. 100. Hair and
Hair Follicle.

A, root of hair ; B, bulb
of the hair; C, internal
root sheath ; Z>, exter-
nal root sheath ; £, ex-
ternal membrane of
follicle; F, muscular
fibers attached to the
follicle ; H, compound
sebaceous gland with
its duct, K\ L, simple
sebaceous gland; M,
opening of the hair
follicle.

Life and Health

excessive warmth. Forming more rapidly than it evapo-
rates, it collects in drops on the surface.

A man's weight may be considerably
reduced within a few hours by means
of the perspiration alone. This may
explain to some extent the weakening
effect of profuse perspiration, as from
" night sweats " of consumption, and dur-
FIG. 101. Concave or ing convalescence in typhoid fever.

Adherent Surface of

the Nail. Experiment 86. Study the openings of the

sweat glands with the aid of a strong magni-
A, border of the root ; B,

whitish portion of semi- fymg glass- They are conveniently examined
lunar shape (the lu- on the palms,
nula) ; C, body of nail.

The continuous line o 291. The Skin as a Regulator of the
around border repre- Temperature of the

sents the free edge.

Body. By means of
the sweat the skin performs a third, and
a most important, function, viz., that of
regulating the temperature of the body.

The blood vessels of the skin, like
those of other parts of the body, are
under the control of the nervous system,
which regulates their diameter. If the FIG IQ2 NaU .n
nervous control be relaxed, the blood Position,

vessels dilate, more blood flows through A, section of cutaneous

them, and more material is brought
to the glands of the skin to be acted
upon.

External warmth relaxes the skin and
its blood vessels. There results an in-
creased flow of blood to the skin, with
increased perspiration. External cold has the opposite
effect.

fold (B) turned back
to show the root of
the nail; B, cutane-
ous fold covering tha
root of the nail; C,
semilunar whitish
portion (lunula) ; D,
body of nail

The Skin and the Kidneys

193

Now, it is a law of physics that the change from liquid
to vapor involves a loss of heat. For instance, a few drops
of ether or of any volatile liquid placed fifl&^HI
on the skin produce a marked sense of
coldness, because the heat necessary
to change the liquid into vapor has been
drawn rapidly from the skin. This
principle holds good for every drop of
sweat that reaches the mouth of a sweat
gland. As the sweat evaporates, it
absorbs a certain amount of heat and
cools the body to that extent.

\292. How the Action of the Skin may
be modified. After profuse sweating we
feel chilly from the evaporation of a
large amount of moisture, which rapidly
cools the surface. When the weather
is very warm the evaporation tends to
prevent the bodily temperature from
rising. On the other hand, if the
weather be cold, much less sweat is
produced, the loss of heat from the
body is greatly lessened, and its tem-

, r c ,,. /r^ (Treated with osmic acid :

perature prevented from falling. Thus showing three outer

it is plain why certain drugs and hot

baths are often given and other efforts

are made to sweat the fever patient.

The increased activity of the skin helps

to reduce the bodily heat.

> 293. The Secretion of Sweat and its

Nervous Control. The sweat glands

are under the control of certain nerve

fibers originating in the spinal cord and

FIG. 103. Transverse
Section through the
Human Skin.

layers of the cuticle, two
in black and a middle
light layer. Below the
inner dark layer, the
active layer, or rete mu-
cosztm, is well shown.
All below is the true
skin. The tortuous
course of a sweat gland
is well marked. The
two round black spots
are fat cells. Magnified
30 diameters.)

194

Life and Health

are not necessarily excited to action by an increased flow
of blood through the skin. In other words, the sweat
glands may be stimulated to increased action, both by an
increased flow of blood, and also by special nerve impulses
sent to them.

These two agencies, while usually working in harmony,
may produce phenomena which are essentially independ-
ent of each other. Thus a strong emotion, like fear, may

cause a profuse sweat to
break out, with cold, pallid
skin. In this case the two
sets of nerves act in the
opposite way. The sweat
glands secrete, but the blood
vessels are constricted.
->294. Absorbent Powers of
the Skin. The skin serves
to some extent as an organ
for absorption. It is capable
of absorbing certain sub-

(In each papilla are seen vascular loops stances to which ft is freely
(dark lines) running up from the vas- .

exposed. Ointments rubbed
in are absorbed by the lym-
phatics in those parts where
the skin is thin, as in the bend of the elbow or knee, and
in the armpits. Physicians use medicated ointments in
this way. House painters are often poisoned by the
absorption of lead into the body through the skin.

A slight amount of water is absorbed in bathing. Sailors

deprived of fresh water have been able to allay partially

their intense thirst by soaking their clothing in salt water.

If the outer skin be removed from parts of the body, the

exposed surface absorbs certain substances rapidly. When

FIG. 104. Papillae of the Skin of
the Palm of the Hand.

cular network below ; the tactile cor-
puscles with their nerve branches
(white lines) which supply the papillae.)

The Skin and the Kidneys

195

the physician wishes remedies to act through the skin, he
sometimes raises a small blister, and dusts over the surface
some drug in the form of a fine powder.

4 295. Necessity for Personal Cleanliness. The surface of
the skin is continually casting off perspiration, oily material,
and dead scales. By friction and
regular bathing we are able to get
rid of a great deal of this waste
material. If this is not frequently
and thoroughly done, the oily secre-
tion retains the particles of waste
substances on the surface of the
body, while dust and dirt collect
and form a layer upon the skin.

As this unwholesome layer is a
fertile soil in which bacteria may
develop, many skin diseases may
result from neglect of personal
cleanliness. It is also highly prob-
able that germs of disease thus
adherent to the skin may be
absorbed into the system. Para-
sitic diseases are greatly favored by
the presence of dirt on the skin.

^296. Why we need to bathe. In
bathing we have two distinct objects
in view, — to keep the skin clean
and to invigorate the body as a
whole. These are closely related,
for the removal of worn-out material from the skin in bath-
ing serves indirectly to give vigor to other organs. Thus
a cold bath is useful locally to cleanse the skin, and also
acts through the nervous system to call out, in response

FIG. 105. Magnified View
of a Sweat Gland with its
Duct.

(The convoluted gland is seen
surrounded with big fat cells
and may 'be traced through
the dermis to its outlet in
the horny layers of the epi-
dermis.)

196 Life and Health

to the temporary loss of heat at the surface, a freer play of
the general vital powers.

297. Hot Baths. Hot baths should be taken at night
before going to bed, as in the morning there is usually
more risk of taking cold. The body is readily chilled if
exposed to cold when the blood vessels of the skin have
been relaxed by heat. Besides their use for the purposes
of cleanliness, hot baths have a sedative influence upon the
nervous system, tending to allay restlessness and weariness.
They are excellent after severe physical or mental work
and give a feeling of restful comfort like that of sleep.

Experiment 87. To illustrate the sense of temperature. Ask the
person to close his eyes. Use two test tubes, one filled with cold and
the other with hot water, or two spoons, one hot and one cold. Apply
each to different parts of the surface and ask the person whether the
touching body is hot or cold. Test roughly the sensibility of different
parts of the body with cold and warm metallic-pointed rods.

Experiment 88. Touch fur, wood, and metal. The metal feels
coldest, although all the objects are at the same temperature. Why ?

Experiment 89. Plunge the hand into water at about 97° Fahr. ;
one experiences a feeling of heat. Then plunge it into water at
about 86° Fahr. ; at first it feels cold, because heat is abstracted from
the hand. Plunge the other hand directly into water at 86° Fahr.
without previously placing it in water at 97° Fahr. ; it will feel
pleasantly warm.

Experiment 90. To illustrate warm and cold spots. With a
blunt metallic point, touch different parts of the skin. Certain
parts feel a sensation of warmth, others of cold, although the tem-
peratures of the skin and of the instrument remain constant.

^ 298. Cold Baths. Cold baths serve as an excellent tonic
and stimulant to the bodily functions. The best time for
a robust person to take a cold bath is in the morning,
immediately after rising.

The Skin and the Kidneys 197

A cold bath which is not followed by reaction is likely
to do more harm than good. The lack of this reaction may
be due to the water being too cold, the bath too prolonged,
or to the bather being in a low condition
of health. The ruddy glow which fol-
lows a cold bath is the main indication
of its favorable influence. After taking
a bath the skin should be vigorously
rubbed dry with a rough towel, and the
clothing at once put on. FlG> Io6. Epitheiiai

^ 299. Precautions in taking a Cold Bath. Cells from the
A daily cold bath, when the body is com- Sweat Glands-
fortably warm, is a safe tonic for almost <The cells ar<; very f:

* . tinct, with nuclei

all persons during the summer months. enclosing pigmentary
It should not be indulged in after severe granulations.- Magni-

. o • e<* 35° times>)

exercise or great fatigue. Serious results

have ensued from cold baths taken when the body was in

a state of exhaustion or of profuse perspiration. Cold baths,

taken regularly, render persons who are susceptible to colds

much less liable to them, and less likely to be disturbed by

sudden changes of temperature.

J 300. Additional Hints on Bathing. Outdoor bathing

should not be indulged in for at least an hour after a full

meal. Except for the robust, it is not prudent to bathe

with the stomach empty.

Hot baths, if taken at bedtime, are often serviceable in
preventing a tKreatened cold or in cutting it short, especially
if the patient goes immediately to bed, with extra clothing
and hot drinks. The free perspiration induced helps to
break up the cold.

The golden rule of all bathing is that it must never
be followed by a chill. If chilliness occur after bathing,
it must immediately be broken up by some appropriate

198

Life and Health

methods, as lively exercise, brisk friction, hot drinks, and

the application of heat.

301. Salt-Water Bathing. Salt water acts more as a

stimulant to the skin, than fresh water. Salt-water bathing

is refreshing and invigorating for
those who are healthy, but the
bather should come out of the
water the moment there is
the slightest feeling of chilliness.
The practice of bathing in salt
water more than once a day is
unhealthf til, and even dangerous.
Only the strongest can sustain
so severe a tax on their power of
endurance. Sea bathing is bene-
ficial in many ways for children,
if their skin reacts well after it.
In all cases, brisk rubbing with
a rough towel should follow.

A, membrane of the hair follicle, n ___

cells with nuclei and pigmentary V 302. Care of the Hair and Nails.

granules; B, external lining of The hairbrush should not be too

stiff, as this increases the tend-
ency toward scurfiness of the head.
Moreover, if the hair is brushed
too long or too hard, the scalp is
greatly stimulated and an increased
production of scurf may result. If
the head be washed too often with soap, its natural secretion is
checked, and the scalp becomes dry and scaly. The various
hair pomades are as a rule undesirable and unnecessary.

The nails should be kept in proper condition, else they are
not only unsightly, but may serve as carriers of germs of
disease. The nails are often injured by too much trimming.
The upper surfaces should on no account be scraped. The
nailbrush is sufficient to cleanse them without impairing their
smooth and polished surfaces.

FIG. 107. Magnified Section of
the Lower Portion of a Hair
and Hair Follicle.

the root sheath ; C, internal lining
of the root sheath ; Z>, cortical or
fibrous portion of the hair shaft;
E, medullary portion (pith) of
shaft ; F, hair bulb, showing its
development from cells from A.

The Skin and the Kidneys 1 99

r 303. Use of Clothing. The chief use of clothing, from a
hygienic point of view, is to assist in keeping the body at
a uniform temperature. It also serves for protection against
injury and for personal adornment. The heat of the body,
as we have learned, is normally about 98^° Fahr. This
varies but slightly in health. A rise of temperature of
more than one degree is a symptom of disturbance. The
normal temperature does not vary with the season. In
summer it is kept down by the rapid evaporation of the
perspiration. In winter it is maintained by more active
oxidation, by extra clothing, and by artificial heat.
y 304. Suggestions for the Use of Clothing. Prudence and
good sense should guide us in the spring in changing
winter clothing for fabrics of lighter weight. A change
from heavy to lighter clothing should be made first in the
outer garments, the underclothing
being changed very cautiously.

The two essentials of healthful
clothing are cleanliness and dryness.
To wear garments that are daily
being soiled by perspiration is a FlG. Io8.7^gitudinalSec-
most uncleanly and unhealthful tion of a Finger Nail,
practice. Clothing, especially Aj last phalanx of the fingers .
woolen underclothing, should be <#» true skin on the dorsal sur-

r - , , face of the finger ; C, epider-

frequently changed. mis . A true skin . £> ^ of

\ Infectious and COntagioUS the nail ; F, superficial layer
,. , , , ,, of the nail; H. true skin of

diseases may be conveyed by the the pulp of the finger
clothing. Hence special care must

be taken that all clothing in contact with sick people is
burned or properly disinfected.

305. Precautions in the Use of Clothing. We should
never sleep in a damp bed or between damp sheets. The
practice of sitting with wet feet and damp clothing is

2OO Life and Health

highly injurious to health. The surface of the body thus
chilled may be small, yet there is a grave risk of serious,
if not of fatal, disease. No harm may be done, even with
clothing wet with water or damp with perspiration, so long
as exercise is maintained, but the failure to change into
dry garments as soon as the body is at rest is fraught with
danger.

Woolen comforters, scarfs, and fur mufflers, so com-
monly worn around the neck, are more likely to produce
throat troubles than to have any useful effect.
(k 306. Bad Effects of wearing tightly fitting Clothing.
The injury to health caused by tight lacing is due to the
compression and displacement of various organs by the
pressure exerted on them. Thus the lungs and the heart
may be compressed, causing short breath on exertion, pal-
pitation of the heart, and other distressing symptoms. The
stomach, the liver, and other abdominal organs are often
displaced, causing dyspepsia and all its attendant evils.

The use of tight elastic bands on the arms or below the
knee is often injurious. They obstruct the local venous
circulation and are a fruitful source of cold hands or feet
and of enlarged or varicose veins.

The compression of the scalp by a tight-fitting hat
often interferes with the local circulation and may cause
headache, neuralgia, or baldnesss. The compression of
the abdomen by a tight belt may interfere with the
descent of the diaphragm.

Tightly fitting boots and shoes often cause corns, bunions,
and ingrowing nails. Boots too narrow in front crowd the
toes together, make them overlap, and render walking diffi-
cult and painful. High-heeled boots throw the weight of
the body forwards, so that the body rests too much on the
toes instead of on the heels.

The Skin and the Kidneys 201

THE KIDNEYS

v 307. General Structure of the Kidneys. The kidneys are

of a reddish-brown color and lie between the upper lumbar
vertebrae and the crest of the hip bone, close against the
rear wall of the abdomen, with the intestines in front of
them. The human kidneys, though somewhat larger, are
of the same shape, color, and general appearance as those
of the sheep, so commonly seen in the markets.

The hollow or concave side of the kidneys is turned
inwards, and the deep fissure of this side, known as the
hilus, widens out to form the pelvis of the kidney. Through
the hilus the renal artery passes into each kidney, and from
each hilus passes outwards the renal vein, a branch of the
inferior vena cava.

A tube, called the ureter, passes out from the concave
border of each kidney, turns downwards, and enters the
bladder in the basin of the pelvis. This tube conveys the
secretion of the kidneys to the bladder.

Experiment 91. Obtain a sheep's kidney in good order. Observe
that its shape is something like that of a bean, and note that the con-
cave part (hilus), when in its normal position, is turned towards the
backbone. Notice that all the vessels leave and enter the kidneys at
the hilus. Observe a small, thick-walled vessel with open mouth, from
which mg,y be pressed a few drops of blood. This is the renal artery.
Pass a bristle down it. With the forceps, or even with a penknife,
lift from the kidney the fine membrane enclosing it. This is the
kidney capsule.

Divide the kidney in halves by a section from its outer to near its
inner border. Do not cut directly through the hilus. Note on the
cut surfaces, on the outer side, the darker cortical portion, and on
the inner side the smooth, pale, medullary portion. Note also the
pyramids of Malpighi.

2O2

Life and Health

J 308, Minute Structure of the Kidneys. The pelvis of the
kidney is surrounded by reddish cones, about twelve in
number, projecting into it, called the pyramids of Malpighi.

The apices of these cones,
known as the papillce, are
crowded with minute open-
ings, the mouths of the urinif-
erous tubules, which form the
substance of the kidney, and
which end at last in dilated
closed sacs called Malpighian
capsules.

v' 309. Function of the Kid-
neys. The Malpighian cap-
sules are really the beginning
of the tubules, for here the
work of excretion begins.
The thin wall of the capil-
laries within each capsule
separates the blood from the
cavity of the tubule. The
blood pressure on the deli-
cate capillary walls causes
the exudation of the -watery

FIG. 109.

Vertical Section of the
Kidney.

A, pyramids of Malpighi ; B, apices, or
papilhe, of the pyramids, surrounded
by subdivisions of the pelvis known
as cups, or calices ; C, pelvis of the
kidney; D, upper end of ureter.

portions of the blood through
the cell walls into the cap-
sule. The epithelial cell membrane allows the water of
the blood with certain salts in solution to pass, but rejects
the albumin.

From the capsules the excretion passes through the
tubules into the pelvis of the kidneys, and on through the
ureters to the bladder. But the delicate epithelial walls
of the tubules through which it passes permit the inflow

The Skin and the Kidneys

203

of urea and other waste products from the surrounding
capillaries.

Thus by a peculiar and delicate kind of filtering process
the fluid portions of the renal secretion with soluble salts, and
the urea with other waste material are separated from the blood.

FIG. 1 10. Vertical Section of the Back.

(Showing kidneys in situ and the relative position of adjacent organs and vessels.
Posterior view.) A, i2th dorsal vertebra; B, diaphragm; C, receptaculum
chyli ; D, small intestines.

204 Life and Health

v 310. How the Action of the Kidneys may be modified.
In the kidneys, as elsewhere, the vaso-motor nerves are dis-
tributed to the walls of the blood vessels and modify the quan-
tity and the pressure of blood in these organs. Thus some
strong emotion, like fear or undue anxiety, increases the blood
pressure, drives more blood to the kidneys, and causes a larger
flow of watery secretion.

In warm weather there is a relaxation of the vessels of the
skin, with a more than ordinary flow of blood, together with
active perspiration. The blood pressure in the kidneys is not
only diminished, but the total quantity passing through them
in a given time is much lessened. As a result, the secretion
of the kidneys is scanty, but it contains an unusual percent-
age of solids.

In cold weather the cutaneous vessels contract, the blood is
driven to the deeper organs with increased pressure, and there
is a less amount of sweat, but an increased renal secretion,
containing a smaller proportion of solids. Thus the skin and
the kidneys work in harmony in their efforts to rid the body
of its superfluous water.

The Renal Secretion. The function of the kidneys is to secrete a fluid
commonly known as the urine. The average quantity passed in twenty-four
hours by an adult is about three pints. Normal urine consists of about 96
per cent of water and four per cent of solids. The latter consist chiefly of
certain nitrogenous substances known as urea and uric acid, a considerable
quantity of mineral salts, and some coloring matter. Urea, the most impor-
tant and most abundant constituent of urine, contains the four elements,
carbon, hydrogen, oxygen, and nitrogen, but nitrogen forms one-half its
weight. While, therefore, the lungs expel carbon dioxide chiefly, the kid-
neys expel urea and other nitrogenous wastes. All these substances express
the result of oxidations going on in the body. The urea and uric acids
represent the final result of the breaking down in the body of nitrogenous
substances, of which albumin is the type.

The Bladder. The bladder is an oval bag situated in the lowest part of
the abdome'n. When full, the bladder is pear-shaped ; when empty, it is
collapsed and lies low in the pelvis. The bladder collects and retains
the urine, which has reached it drop by drop from the kidneys through the
ureters, until a certain quantity accumulates. Owing to the distention of
the bladder, a feeling of uneasiness arises which compels the expulsion of
its contents.

The Skin and the Kidneys 205

311. Effects of Alcohol upon the Kidneys. The duty
of the kidneys in ridding the blood of waste products, and of
any foreign or poisonous material introduced, must be car-
ried on continually, or the whole body suffers from the
bad effects of the retained waste matters.

These two important organs, with their large blood vessels
conveying enormous amounts of blood to and from their
tissues, feel very quickly the presence of alcohol. Alco-
holic liquors may irritate the delicate renal tissues and
speedily disturb their normal action in excreting the proper
waste materials from the blood.

The continued congestion of the kidneys, together with
repeated irritation of their structural cells, resulting from
strong drink, tends to cut off their needed nutrition and
usually results in a series of renal disturbances.

The urea, which is a poison and which must be removed,
may be retained in the system, while the albumin, which
is essential to healthy blood, may be filtered away through
the diseased kidneys. The presence of albumin in the
renal excretion is often an important symptom to the
physician in making a diagnosis of the insidious and fatal
disease known as albuminuria^ or " Bright's disease."

.Repeated indulgence in alcoholic liquors often results in
the infiltration of fat cells into the cortical substance of
the kidneys. This is known as " fatty degeneration of the
kidneys."

CHAPTER X
THE NERVOUS SYSTEM

y 312. The Nervous System, the Master Organs. We are
now prepared to study a higher, a more wonderful and
complex agency, — the nervous system, the master organs,
which control, regulate, and direct every other organ of
the human body.

The nervous system is the medium through which all
impressions are received. It connects all the parts of the
body into an organism in which each acts in harmony with
every other part for the good of the whole. It animates
and governs all movements, voluntary or involuntary, —
secretion, excretion, nutrition ; in fact, all the processes of
organic life are subject to its regulating power.

313. The Nervous System brings us into Relation with
the World around us. In men and other highly organized
animals nerves are found in every organ of the body. They
come into contact with the most minute muscular fibers ;
they are closely connected with the cells of the glands and
are found in the coats of even the smallest^ blood vessels.
They are among the chief constituents of the sense organs,
including the skin. When we hear, our nerves of hearing
are bringing us into relation with the outer world. So sight
opens up to us another gateway of knowledge.

In brief, the nervous system is the system of organs
through which we are brought into relation with the world
around us.

206

The Nervous System 207

X 314. Nerve Cells. However complicated the structure
of the nerve tissue in man seems to be, it is found to con-
sist of only two different elements, nerve cells and nerve fibers.
These are associated and combined in many ways. They
are arranged in distinct masses called nerve centers, or in
the form of cords known as nerves.

Nerve cells consist of masses of protoplasm, with a large
nucleus and nucleolus. A number of processes branch off
from them, some cells giving off one or two,
others many.

Certain forms of cells are found only in
particular parts of the nervous system. Thus,
we have in the spinal cord the large,- irregular
cells with many processes, and in the brain
proper the three-sided cells with a process
jutting out from each corner (Fig. 3).

315. Structure of Nerve Fibers. The nerve FIG. in.
fibers, the essential elements of the nerves, Nerve Cells
somewhat resemble tubes filled with a clear,

Spinal Cord.

jelly-like substance. They consist of a rod,
or central core, continuous throughout the whole length of
the nerve, called the axis cylinder. This core is surrounded
by the white substance of Schwann, or medullary sheath,
which gives the nerve its characteristic ivory-white appear-
ance. The whole is enclosed in a thin, delicate sheath
known as neurilemma.

The axis cylinder generally passes without any break
from the nerve centers to the end of the fibers: The
outer sheath (neurilemma) is also continuous throughout
the length of the fibers.

The medullary sheath, on the other hand, is broken at
intervals of about one twenty-fifth of an inch, and at the
same intervals nuclei are found along the fiber, around

208 Life and Health

each of which is a minute protoplasmic mass. Between
each pair of nuclei the sheath is interrupted. This point
is known as the node of Ranvier (Figs. 1 13 and 1 14).

Experiment 92. Obtain a small piece of nerve from the market.
Place the least bit of it on a glass slide. Tease it out lengthwise
with needles. Note the delicate thread-like fibers. Examine with
the high power of the microscope.

316. White and Gray Nerve Fibers. Some nerve fibers
have no inner sheath (medullary), the outer alone protect-
ing the axis cylinder. These
are known as the non-medul-
lated fibers. They are gray,
while the ordinary medullated
fibers are white in appearance.
The white nerve fibers form
most of the white part of the
brain and of the spinal cord,

Pta I.». Nerve Cells from the and fa f fa

Gray Matter of the Brain. . fe

bro-spinal nerves.

The gray fibers occur chiefly in branches from the sympa-
thetic ganglia, though found to some extent in the nerves
of the cerebro-spinal system.

^ 317. General Structure of Nerves. The separate micro-
scopic threads or fibers, bound together in cords of various
sizes, form the nerves. Each strand or cord is surrounded
and protected by its own sheath of connective tissue.
According to its size a nerve may have one or many of
these strands.

The whole nerve, not unlike a minute tendon in appear-
ance, is covered by a dense sheath of fibrous tissue, in
which the blood vessels and lymphatics are distributed to
the nerve fibers.

The Nervous System

209

/> 318, The Functions of the Nerve Cells and Nerve Fibers.
The nerve cells are a highly active mass of living material.
They find their nourishment in the
blood, which is supplied to them in
abundance. We may think of the
nerve cells as a sort of a miniature
manufactory, deriving their material
from the blood, and developing from
it nervous energy.

' The nerve fibers, on the other hand,
are conductors of nervous energy, They
furnish a pathway along which the
nerve energy generated by the cells
may travel. The fibers can also gener-
ate energy, yet it is their special func-
tion to conduct impulses to and from

the cells

319. The Nervous System compared
to a Telegraphic System. It will help
us the better to understand the com-
plicated functions of the nervous system
if we compare it to a telegraph system.
The brain and the spinal cord are the
main offices, and the multitudes of nerve
fibers branching off to all parts of the
body are the wires. By means of these,
nerve messages are constantly being sent
to the cerebro-spinal center to inform it
of what is going on in various parts of
the body, and asking what is to be done
in each case. The cerebro-spinal center,
on receiving the intelligence, at once
sends back the required instructions. Countless messages are
sent to and fro with unerring accuracy and marvelous rapidity.

Thus, when we accidentally pick up something hot, it is
instantly dropped. A nerve impulse passes from the nerves of

?IG. 113. Medullated
Nerve Fibers.

a medullated nerve fiber,
showing the subdivision
of the medullary sheath
into cylindrical sections
imbricated with their
ends; a nerve corpuscle
with an oval nucleus is
seen between the neuri-
lemma and the medullary
sheath. B, a medullated
nerve fiber at a node or
constriction of Ranvier;
the axis cylinder passes
uninterruptedly from one
segment into the other,
but the medullary sheath
is interrupted.

2IO

Life and Health

touch in the fingers to the cerebro-spinal center, which at once
hurries off its order along another set of nerves for the hand
to drop the hot object.

f 320. Divisions of the Nervous System. The nervous
system consists of two great divisions : the cerebro-spinal
system and the sympathetic system.

The first is the great nerve center of
the body, the cerebro-spinal system, which
rules the organs of animal life, and
includes the brain, the spinal cord, and
the cerebro-spinal nerves.

Nerves are given off from the brain
and the cord, and form the mediums of
communication between them and the
external parts of the body.

The second division is the sympathetic
system. This consists of numerous small
nerve centers arranged in oval masses
varying greatly in size, called ganglia,
or knots. These are either scattered

(Two nerve fibers, show- • •, •> ,-, -, .-> •, , ,

ing the nodes or con- "regularly through the body or arranged
strictions of Ranvier in a double chain of knots lying in the

Tht^utr^het'th fr°nt Of the SPine' With!« the CheSt a"d

has been dissolved abdomen. From this chain large num-

££ •SSgT.ffi bers of.nerves are Siven off- which end
indicate the nerve chiefly in the organs of digestion, circu-

FIG. 114. Non-
Medullated Fibers.

^ 321. The Brain as a Whole. The
brain is the seat of the intellect, the will, the affections, the
emotions, the memory, and sensation. It has also many
other and complex functions. In it are established many
reflex, automatic, and coordinating centers, which are as inde-
pendent of consciousness as are those of the spinal cord.

The Nervous System

322. Weight of the Brain. The

average weight of the adult human
brain is about fifty ounces for men
and forty-five ounces for women.
Other things being equal, the size
and weight of the brain bear a general
relation to the mental power of the
individual. As a rule, a large, healthy
brain stands for a vigorous and supe-
rior intellect.

The brains of many eminent men
have been found to be eight to twelve
ounces above the average weight, but
there are notable exceptions. The
brains of idiots are usually small and
badly developed. The brain and head
of a child are very large in proportion
to the rest of the body.
*323, The Cerebrum. The three
principal masses which make up the

brain when .viewed as a whole are :
,/

1. The cerebrum, or brain proper.

2. The cerebellum, or lesser brain.

3. The medulla oblongata.

The cerebrum comprises nearly
seven-eighths of the entire mass and
fills the upper part of the skull. It
consists of two halves, the right and
left cerebral hemispheres. These are
almost separated from each other by
a deep median fissure. Each of the
hemispheres is subdivided into three

21 I

FIG. 115. Diagram of a

Motor Nerve Cell.
(Showing its long, unbranched
process (with two little lateral
offshoots), with motor endings
in striated, voluntary muscle
tissue. By comparison with
Figs. 113 and 114 the several
unmarked parts in this dia-
gram may be readily under-
stood.)

212 Life and Health

lobes, so that the entire cerebrum is made up of six
distinct lobes.

The cerebrum has a peculiar convoluted appearance, its
deep folds being separated by fissures, some of them nearly
an inch in depth.

It is composed of both white and gray matter. The
former comprises the greater part of the mass, while the
latter is spread over the surface in a layer about one-eighth
of an inch thick. The gray matter is the portion having
the highest functions, and its quantity is largely increased
by its arrangement in convolutions.

The cerebrum is the seat of the sensations, the intellect,
the will, and the emotions.

324. The Convolutions of the Cerebrum. The convolutions
of the cerebrum are without doubt associated with all those
higher actions which distinguish man's life ; but all the
convolutions are not of equal importance.

The convolutions in the human brain are more promi-
nent than are those in the brain of the higher animals
most nearly allied to man, although some species of ani-
mals, not especially intelligent, have marked cerebral con-
volutions. The higher races of men have more marked
convolutions than have those that are less civilized.

325. Under Surface of the Brain. The under surface
of the brain, which rests on the floor of the skull, shows
the origin of important nerves called the cranial nerves; the
cerebellum ; the structure connecting the optic nerves (optic
commissure) ; the bridge of nervous matter (pons Varolii)
connecting the two hemispheres of the cerebellum ; and
lastly, numerous and well-marked convolutions.

•/ 326. The Cerebellum. The cerebellum, or lesser brain,
lies in the back of the cranium and is covered over by
the posterior lobe of the cerebrum. It is, as it were,

The Nervous System

213

astride of the back of the cerebro-spinal axis and con-
sists of two hemispheres joined by a central mass. On its
under surface is a depression which receives the medulla
oblongata (Figs. 119 and 121).

The cerebellum is connected with other parts of the
nervous system by strands of white matter on each side,
radiating from the
center and divided
into numerous
branches. Around
these branches
the gray matter
is arranged in a
beautiful manner,
suggesting the
leaves of a tree :
hence its fanciful
name, arbor vitce,
or the tree of life.
*327. The Func-
tions of the Cere-
bellum. The
functions of the
cerebellum are not

certainly known. FlG- IJ6- The Upper Surface of the Cerebrum.
It aDDCarS tO aid (Showing its division into two hemispheres, and also the

convolutions.)

in the control of

the muscles of the Dody ; that is, it serves to bring the various
muscular movements into harmonious action. The mechanism
by which it does this has not yet been clearly explained.
In an animal from which the cerebellum has been removed
the functions of life are not destroyed, but the power of
either walking or flying straight is temporarily lost.

2I4

Life and Health

Disease or injury of the cerebellum usually produces
blindness, dizziness, a staggering gait like that of a drunken
man, and a feeling of insecurity in maintaining right posi-
tions during the execution of movements. There is no loss
of consciousness or other disturbance of the mental functions.

FIG. 117. A Vertical Section of the Brain.

A, frontal lobe of the cerebrum; £, parietal lobe; C, parieto-occipital lobe
with fissure between this lobe and D, the occipital lobe; E, cerebellum;
F, arbor vitae ; //, pons Varplii ; K, medulla oblongata ; L, portion of lobe
on the opposite side of brain. The white curved band above H represents
the corpus callosum.

Experiment 93. Examine the least bit of the 'white matter of the
brain under a microscope of high power. The fibers are the ordinary
white fibers. Now examine the gray matter and note the elongated
cells with their long, fine branches.

328. The Membranes of the Brain. The brain and spinal
cord are protected by three important membranes^ known as
the meninges, — the dura mater, the arachnoid, and the pia mater.

The Nervous System 215

The outer membrane, the dura mater, is much thicker and
stronger than the others, and closely lines the inner surface
of the skull and forms a protecting covering for the brain.

The arachnoid is a thin membrane which secretes a serous
fluid that keeps the inner
surfaces moist.

The pia mater is a very
delicate vascular membrane
which covers the convolu-
tions, dips into all the
fissures, and even pene-
trates into the interior of
the brain.

329. The Medulla Oblon-
gata. The medulla oblongata
is the enlarged upper part
of the spinal cord lying
within the cavity of the
skull. It is immediately
under the cerebellum and
forms the connecting link
between the brain and the
spinal cord. It is about an
inch and a quarter long,
and from one-half to three-
fourths of an inch wide at

its upper part (Fig. 119). FIG. 118. Illustrating the General Ar-
The gray matter of the rangement of the Nervous System.
,,,.,, .' (Posterior view.)

medulla is broken up into

masses which serve as centers of origin for various nerves.

330. The Functions of the Medulla Oblongata. The
functions of the medulla oblongata are closely connected
with the vital processes. It is a great nerve tract for

2 1 6 Life and Health

transmitting sensory and motor impressions from the cord
to the brain and return.

The medulla is also the seat of a number of reflex centers
connected with the influence of the nervous system on the
blood vessels, the movements of the heart, respiration,
swallowing, and the secretion of saliva.

In the medulla also are centers for coughing, vomiting,
swallowing, and the dilation of the pupil of the eye. It is
also in part the deep origin of important cranial nerves.

Experiment 94. To show the brain. A sheep's or calf's brain is
to be preferred, on account of its larger size. Get one fresh from the
butcher. Pay him to dissect away the skin and muscles of the skull,
under your direction, and to saw open the cranium in a circular direc-
tion. Take time, and remove the sawed top with great care, tearing
away the dura mater from the bones.

Now cut away enough of this membrane so that the sides of the
skull can be sawed and torn away, to allow us to lift out the brain,
with proper dissection, in as perfect a state as need be. Put all the
torn parts and membranes back into place.

Note the dura mater, the arachnoid lining it, and the pia mater
closely attached to the brain. Find the cerebrum, or big brain, the
cerebellum, or little brain, the medulla, and the stumps of the cranial
nerves, especially the stumps of the optic nerves. The brain should
be first examined as a whole, and compared with the description
given in the text, or the pictures of the human brain.1

NOTE. — A fresh brain is too soft for handling or for careful study.
Hence it should be hardened and made ready for use several weeks
before it is needed for class use. A mixture of \ ounce of bichromate
of potash and i ounce of a 40 per cent solution of formalin to about
I quart of water makes a useful hardening and preserving fluid. A
mixture of two-thirds strong alcohol and one-third 2 per cent solution
of formalin is also recommended.

1 Space does not allow us to give in necessary detail the directions for
the experimental study of the brain. Such directions are admirably given
in Brown's Physiology for the Laboratory, a book already referred to on
page 20.

The Nervous System

217

331, The Cranial Nerves. The cranial or cerebral nerves
consist of twelve pairs of nerves which pass from the brain
through different openings in the base
of the skull. They are distributed
over the head and face, and also to
some parts of the trunk and to cer-
tain internal organs. These nerves
proceed in pairs from the correspond-
ing parts on each side of the brain.

332. Distribution and Functions
of the Cranial Nerves. The cranial
nerves are thus arranged in pairs :

The first pair are the olfactory nerves,
the special nerves of smell.

The second pair are the optic nerves,
which pass to each eyeball, and are
devoted to sight.

The third, fourth, and sixth pairs
control the muscles of the eyes.

Each of the fifth pair of nerves is FIG. 119. Anterior View of
in three branches and proceeds mainly the Medulla Oblongata.
to the face. They are called tri-facial A, chiasm of the optic nerves ;
nerves, and are partly sensory and ^, optic tracts ; C, motor oculi
partly motor. communis ; A fifth nerve ; *>

The seventh pair, the facial nerves,
control the facial muscles. The eighth
pair are the auditory, or nerves of hear-
ing, and are distributed to- the special
organs of hearing.

The ninth pair, the glossopharyngeal
nerves, are partly sensory and partly
motor. Each nerve contains two roots :
one a nerve of taste, which spreads
over the back part of the tongue; the other a motor nerve,
which controls the muscles engaged in swallowing (Fig. 123).

The tenth pair, the pneumogastric nerves, also known as the
vagi, or wandering nerves, are the longest and most important
of all the cranial nerves. They are both motor and sensory.

motor oculi externus; F, facial
nerve; If, auditory nerve;
/, glossopharyngeal nerve ;
K, pneumogastric ; Z,, spinal
accessory; M, cervical nerves;
N, upper extremity of spinal
cord; O, decussation of the
anterior pyramids ; P, hypo-
glossal nerve ; JR, anterior
pyramids ; S, pons Varolii.

2 1 8 Life and Health

Passing from the medulla, they descend near the oesophagus,
sending off, on their way, branches to the windpipe, the larynx,
the chief digestive organs, the lungs, and the heart (Fig. 125).

The eleventh pair, the spinal accessory nerves, supply some
of the muscles of the neck and the back.

The twelfth pair, the hypoglossal nerves, control the move-
ments of the tongue in speech and in swallowing.

Experiment 95. If the brain has been carefully removed, most of
the twelve pairs of cranial nerves may be identified by careful study.
Such as are found may be compared with the cranial nerves indicated
on a diagram of the human brain.

333. The Spinal Cord. The spinal cord is a column of
grayish-white, soft substance, which extends from the base
of the skull to the lower border of the first lumbar verte-
bra, where it narrows off into a slender filament. It is
continuous with the medulla oblongata and is lodged in the
canal of the spinal column.

The spinal cord is from sixteen to eighteen inches long
and has about the thickness of one's little finger, weigh-
ing about one and one-balf ounces. Like the brain, it is
enclosed in three membranes, which protect the delicate
cord and convey vessels for its nourishment. The% space
between the two inner membranes contains a small quan-
tity of fluid, supporting the cord, as it were, in a water
bed. It is thus guarded against shocks.

334. Structure of the Spinal Cord. The arrangement of
the parts of the spinal cord is best understood by a trans-
verse section. Two fissures, one behind, the other in front,
penetrate deeply into the cord, very nearly dividing it into
lateral halves. In the middle of the isthmus which joins
the two halves is a very minute opening, the central canal,
which extends the entire length of the cord^

The spinal cord, like the brain, consists of gray and white
matter, but the arrangement is different. In the brain the

The Nervous System 2 1 9

white matter is within, and the gray matter is on the
surface. In the cord the gray matter is arranged in two
half-moon-shaped masses, the backs of which are connected
at the central part. The white matter, consisting mainly
of fibers, running for the most part in the direction of the
length of the cord, is outside of and surrounds the gray
crescents.

Thus each half or side of the cord has its own gray
crescent, the horns of which point one forwards and the
other backwards, called respectively the anterior and posterior
cornua, or horns.

It will also be seen that the white substance itself, in
each half of the cord, is divided by the horns of the gray
matter and by fibers passing from them into three parts,
which are known as the anterior, posterior, and lateral
columns (Fig. 120).

Experiment 96. Procure at the market an uninjured piece of the
spinal cord from the loin of mutton or the sirloin or the rib of beef.
After noting its general character while fresh, preserve it in one of
the fluids just mentioned (note, p. 216), until it is sufficiently hard to
be cut in sections.

335. The Spinal Nerves. From the gray matter on each
side of the spinal cord thirty-one spinal nerves are given off
and distributed chiefly to the muscles and the skin. They
pass out at regular intervals on each side of the canal, by
small openings between the vertebrae.

Each spinal nerve has two roots, one from the anterior,
the other from the posterior, portion of the cord. These
unite and run side by side, forming as they pass between
the vertebrae one silvery thread, or nerve trunk. Although
bound up in one bundle, the nerve fibers of the two roots
remain quite distinct and perform two entirely different
functions.

22O

Life and Health

c--

336. Motor and Sensory Nerves. After leaving the spinal
cord each nerve divides into minute branches which are

distributed through the muscles
and terminate on the surface of
the body.

The anterior roots become motor
nerves, their branches being dis-
tributed to certain muscles of the
body to control their movements.

The posterior roots develop into
sensory nerves, their branches being
distributed through the skin and
Side View of the over the surface of the body to
become nerves of touch.

In brief, the spinal nerves divide
and subdivide to reach with their
twigs all parts of the body and
connect every organ with the brain.

The spinal nerves themselves are
merely conductors to carry messages
to and fro. They neither issue com-
mands nor feel a sensation.

337. Functions of the Spinal Cord. The spinal cord is
the principal channel through which all impulses from the
trunk and extremities pass to the brain, and all impulses to
the trunk and extremities pass from the brain. That is,
the spinal cord receives from various parts of the body by
means of its sensory nerves certain impressions and con-
veys them to the brain, where they are interpreted.

The cord also transmits by means of its motor nerves
the commands of the brain to the voluntary muscles and
so causes movement. Thus, when the cord is divided at
any point, compressed, as by a tumor or broken bone, or

FIG. 120.
Spinal Cord. (Showing the
fissures and columns.)

A, anterior median fissure; B, pos-
terior median fissure; C, ante-
rior lateral fissure ; D, posterior
lateral fissure ; £, lateral col-
umn ; F, anterior column ; G,
posterior column ; H, posterior
median column; K, anterior
root; L, posterior root; M,
ganglion of N, a spinal nerve.

The Nervous System

221

disorganized by disease, the result may be a complete loss
of sensation and voluntary movement below the point of
inj ury .

If by accident
the spinal cord is
injured at some
point, all sensa-
tion and power
of motion may
be lost below
that spot. The
impulse to move-
ment started in
the brain by the
will does not
reach the mus-
cles, because
traveling down
the spinal cord,
it cannot pass the
seat of injury. FlG. I2I The Base of the Brain.

So the impres- A, anterior lobe of the cerebrum; B, olfactory nerve;
sion produced bv *^' sPnen°id portion of the posterior lobe; D, optic

pricking the leg
with a pin, which,
before pain can be
felt, must travel
up the spinal cord
to the brain, cannot reach the brain because the injury
obstructs the path. The telegraph wire has been cut, and
the message can no longer be sent.

•/• 338. The Spinal Cord as a Reflex Center. Besides serv-
ing as a great nerve conductor to carry sensations to the

chiasm ; £, optic tract ; F, abducens ; H, M, hemispheres
of the cerebellum ; A', occipital portion of the occipital
lobe ; L, fissure separating the hemispheres; N, medulla
oblongata ; O, olivary body ; />, anterior pyramids ; ft,
pons Valorii; S, section of olfactory nerve, with the
trunk removed to show sulcus in which it is lodged ;
T, anterior extremity of median fissure.

222 Life and Health

brain and bring back its orders, the spinal cord is also an
independent center for what is called reflex action. By means
of its sensory nerves it receives impressions from certain
parts of the body, and on its own authority sends back
instructions to the muscles by its motor nerves, without con-
sulting the brain. This constitutes reflex action, so called
because the impulse sent to the spinal cord by certain sen-
sory nerves is at once reflected or sent back as a motor
impulse to the muscles (Fig. 122).

< 339. Reflex Action through the Spinal Cord. This reflex
action through the spinal cord is a most important matter.
This power is possessed only by the gray matter of the
cord, the white substance being simply a conductor.

As already mentioned, certain groups of nerve cells in
the medulla oblongata preside over specific functions of
animal life. Thus, there are centers for maintaining the
action of the heart and the movements of breathing. Low
down in the cord also, in the lumbar region, are centers
for the control of the various abdominal organs. Numerous
other reflex centers are described by physiologists.
7^ 340. The Brain as a Reflex Center. The brain, as we
have just stated, is the seat of consciousness and intelli-
gence. It is also the seat of many reflex, automatic, and
coordinating centers. These give rise to certain reflex
actions which are as entirely independent of consciousness
as are those of the spinal cord.

These acts take place independently of the will, and
often without the consciousness of the individual. Thus, a
sudden flash of light causes the eyes to blink, as the result
of reflex action. The sudden start of the whole body at
some loud noise, the instinctive dodging a threatened blow,
and the springing back from sudden danger, are also the
results of this reflex action.

The Nervous System 223

x 341. Importance of Reflex Action. Reflex action is a
marvelous provision of nature for our comfort, health, and
safety. Its vast influence is not realized, as its numberless
acts are continually going on without our knowledge. In
fact, the greater part of nerve power js expended to pro-
duce reflex action. The conscious centers are thus relieved
of a vast amount of work. It would be impossible for the
brain by serving as a " thinking center " to control every
act of our life.

The fact that the gray cells of the spinal cord can origi-
nate a countless number of reflex and automatic actions
is not only of great importance in protecting the body from
injury, but increases vastly the range of our activities.

Even walking, riding the bicycle, writing one's signature,
"playing at sight " a difficult piece of music, and number-
less other such acts may become reflex movements. To
learn how, requires, of course, the action of the brain, but
by frequent repetition the muscles become so accustomed
to certain successive movements that they are continued
by the cord without the action of the brain.

We may thus acquire a sort of artificial reflex action,
often called "unconscious cerebration," which in time
becomes in a way a part of our organization and is carried
on without will power or even consciousness.1

Thus, while the hands are busily doing one thing, the
brain can be intently thinking of another. In fact, any
attempt to control reflex action is more apt to hinder than
to help. In coming rapidly down stairs, for instance, the

1 There is a story, which is creditable enough, though it may not be
true, of a practical joker, who, seeing a discharged veteran carrying home
his dinner, suddenly called out " Attention ! " whereupon the man instantly
brought his hands down, and lost his mutton and potatoes in the gutter.
The drill had been thorough, and its effects had been embodied in the man's
nervous structure. — HUXLEY'S Lessons in Elementary Physiology.

224

Life and Health

descent will be made with ease and safety if the spinal
cord is allowed entire charge of the act, but the chances of
stumbling or of tripping are very much increased if each

step be taken as the result of the

will power.

Experiment 97. To illustrate reflex
action by what is called knee-jerk. Sit
on a chair and cross the right leg over
the left one. With the tips of the fingers
or the back of a book strike the right
ligamentum patellae. The right leg will
be raised and thrown forward with a jerk,
owing to the contraction of the quadriceps
muscles. An appreciable time elapses
between the striking of the tendon and
the jerk. The presence or absence of
the knee-jerk may be a most significant
symptom to the physician.

7-342. The Sympathetic System.

small cells of this part of the Running along each side Qf the
cord (3). In some unknown

way this impulse passes across spine, from the base of the skull

the gray part of the cord to to the coccyx is a chain of nerve
the large cells of the anterior J

root (5), the cells of this part knots, or ganglia. These ganglia,
being connected by their axis twenty-four on each side, and their

cylinder with the efferent fibers

(6). These convey the stim- branches form the sympathetic
ulus to the fibers of the muscle System, as distinguished from the

(7) which accordingly contract. ,_,

Where the brain is concerned cercbro-spmal system. The sym-
in the action the circuit is pathetic ganglia are connected with

longer through S and M. , . , ,

each other and with the sensory

roots of the spinal nerves by a network of gray nerve fibers.
At the upper end the chain of each side passes up into
the cranium and is closely connected with the cranial
nerves. In the neck, branches pass to the lungs and the
heart. From the ganglia in the chest these nerves form

FIG. 122. Dr. Waller's Dia-
grammatic Illustration of
the Reflex Process.

From the sentient surface ( I ) an
afferent impulse passes along
(2) to the posterior root of the
spinal cord, the nerve fibers of
the posterior root ending in
minute filaments among the

The Nervous System.

225

FIG. 123. The Cervical and Thoracic Portion of the Sympathetic Nerve
and its Main Branches.

A, right pneumogastric ; B, spinal accessory; C, glossopharyngeal; Z>, right
bronchus ; £, right branch of pulmonary artery ; F, one of the intercostal nerves ;
If, great splanchnic nerve ; K, solar plexus ; L, left pneumogastric ; M, stomach
branches of right pneumogastric ; N, right ventricle ; O, right auricle ; P, trunk
of pulmonary artery ; R, aorta ; S, cardiac nerves ; 7"1, recurrent laryngeal nerve ;
U, superior laryngeal nerve ; K, submaxillary ganglion ; W, lingual branch of
the fifth nerve ; X, ophthalmic ganglion ; Y, motor oculi externus.

226 Life and Health

great networks, or plexuses, from which branches pass to
the stomach, the liver, the intestines, the kidneys, and other
abdominal organs. A similar network of fibers is situated
lower down in the pelvis, from which branches are dis-
tributed to the pelvic organs.

(I 343. The General Functions of the Sympathetic System.
The sympathetic system exercises a superintending influ-
ence over the greater part of the internal organs of the
body, controlling to a certain extent the functions of diges-
tion, nutrition, circulation, and respiration.

This influence is generally different from that conveyed
to the same organs by fibers running in the spinal or cranial
nerves, or is even opposed to it. Thus, irritation of certain
cranial nerve fibers, as those of the vagus, slows the heart
beat, but the irritation of certain sympathetic fibers which
go to the heart quickens its beat.

The controlling influence of the sympathetic system does
not originate in the system itself, but is derived from the
spinal cord or from the brain. We may, for convenience,
think of this system, not as a separate nervous system, but
as an outlying part of the cerebro-spinal system, — a series of
ganglia through which the fibers of a part of the trunk
of each spinal nerve pass on their way to the important
internal organs of the body.

/ 344. Some Special Functions of the Sympathetic System.
The sympathetic nerves affect directly only those processes
that are beyond the control of the will.

If it»were not for this action of the sympathetic nerves,
the heart would stop beating during sleep, digestion would
cease, and breathing would te suspended. Gentle irritation
of these nerves, induced by contact of food in the stomach,
causes that organ to begin the churning motion needed for
digestion.

The Nervous System

227

Various emotions also have a reflex
action upon the sympathetic system.
Thus terror dilates the pupils of the
eyes, fear acts upon the nerves of the
small blood vessels of the face to pro-
duce pallor, and the sight of an acci-
dent, or even the emotions produced by
hearing of one, may excite nausea and
vomiting.

The maintenance of the tone of the
arteries all over the body, as we have
learned, is one of the special functions
of the sympathetic system (sec. 232).
* 345, Need of Rest. The tissues of
the body, as has been emphasized in
the preceding chapters, are subject to
constant waste, which goes on every
moment, from the first breath of
infancy to the last moment of old age.
We should speedily exhaust our vitality
from this continual loss, but for its
constant renewal. This exhaustion of
life is increased by exertion, and the
process of repair is vastly promoted by
rest. Thus, while exercise is a duty,
rest is equally imperative.

The eye, when exact ingly used in
fine work, should have frequent inter-
vals of rest in a few moments of dark-
ness, by closing the lids. The brain
should have occasional seasons of rest
and refreshment by a dash of cold
water upon the forehead, and a brief

FIG. 124. Nerve Trunks
of the Right Arm.

228 Life and Health

walk with slow and deep inspirations of fresh air. The
muscles, long cramped in a painful attitude, should be
rested as often as may be by change of posture or by a
short, brisk walk.

346. Benefits of Rest. There is too little repose in our
daily life. A sense of fatigue is the mute appeal of the
body for a brief respite from labor, which should, if possi-
ble, be heeded. The feeling that even a ten-minute rest is
so much time lost is a mistake. It is a gain of physical
strength, of mental vigor, and of the total amount of work
done.

The merchant burdened with the cares of business life,
the ambitious student overanxious to win success in his
studies, the housewife wearied with her many hours of
exacting toil, each would get through the task with less
loss of vital force by devoting a few minutes every day
to absolute rest of the strained muscles and overtaxed
nerves.

It is sound physiology to cease from the usual routine
of six days of mental or physical work and to rest both the
mind and the body on the seventh.

347. The Importance of Sleep as a Periodical Rest.
Sleep is the most marked manifestation of the periodic
and physiological rest by which Nature refreshes us. It
is during the periods of sleep that the energy expended in
the activities of the waking hours is mainly renewed.

The need of sleep is self-evident, and the loss of it
is a common cause of the impairment of health. While
we are awake and active the waste of the body exceeds
the repair ; but when we are asleep the waste is diminished.
The organic functions, such as are under the direct control
of the sympathetic nervous system, — circulation, respira-
tion, and digestion, — are diminished in activity during

The Nervous System 229

sleep. The pulsations of the heart and the respiratory
movements are less frequent.1

348. The Amount of Sleep required. No precise rule
can be laid down concerning the amount of sleep required.
It varies with age, occupation, temperament, and climate
to a certain extent. An infant spends the greater part of
its time in sound sleep. Adults of average age who work
hard with their hands or brain usually require at least
eight hours of sleep.

Personal peculiarities, and perhaps habit to a great extent,
exert a marked influence. Throughout his long and active
life Frederick the Great never slept more than five or six
hours in the twenty-four. Napoleon slept but four hours
a day. On the other hand, some of the busiest brain
workers require at least eight or nine hours of sound sleep
every night.

349. Practical Rules about Sleep. Children should not
be allowed to play boisterously just before bedtime, nor
should their minds be excited with weird goblin stories, or a
long time may pass before the wide-open eyes and agitated
nerves become composed to slumber.

At all ages the last hour before sleep should, if possible,
be spent quietly, to smooth the way towards sound and
refreshing rest. Medicines should not be taken to induce
sleep except on the advice of a physician.

1 Remarkable instances are cited to illustrate the imperative demand
for sleep. Cavalrymen and frontiersmen have slept soundly in the saddle
during the exhausting campaigns against the Indians. A case is reported
of a captain of a British frigate who fell asleep and remained so for two
hours beside one of the largest guns of his vessel, the gun being served
vigorously all the time. Whole companies of men have been known to
sleep while on the march during an arduous campaign. Gunner boys have
been known to fall asleep during the height of a naval battle, owing to the
fatigue occasioned by the arduous labor in carrying ammunition for the
gunner.

230 Life and Health

It is better, as a rule, not to engage in severe study
just before bedtime. One hour of morning or day study
is worth a much longer time late at night. It is, therefore,
an economy both of time and of nerve force to use the
day hours and the early evening for study.

The so-called " cat naps " should never be made to serve
as a substitute for a full night's sleep. Late hours are
usually associated with exposure, excitement, and various
other drains upon the nerve force, and hence are injurious.

350, General Effect of Alcohol upon the Nervous System.
We have learned in the preceding chapters that alcohol
tends to a serious disturbance of the tissues of the body.
The direct influence of this narcotic upon the nervous
system is marked even when taken in small quantities.

In the early stages, alcohol acts upon the nervous tissues
as does ether, to excite both the cerebral and the spinal
centers. This is rapidly followed by a marked depressant
action upon both the sensory and motor nerves.

351. Effect of Varying Amounts of Alcohol upon the
Brain. Scientific investigation has ascertained numerous
facts concerning the influence of alcohol, when used in
varying amounts, on the structure and function of the
brain. A single small dose — half a pint of beer — has
been shown to weaken the mental power required to carry
on the processes of adding, committing to memory, asso-
ciation of ideas ; also the power of perception and of atten-
tion to simple sense impressions. Larger quantities cause
a more rapid decrease of power, and the evil effects continue
longer, sometimes until the evening of the next day.1

1 Dr. A. Forel, formerly professor of psychiatry in the University of
Zurich, says concerning the effect* of beer drinking upon the students of
Germany: "One only needs to study in Germany the beer jokes, beer con-
versation, and beer literature. They have stifled in Germany the idealism,

The Nervous System

231

352. No Precise Boundary in the Different Stages of
Alcoholic Intoxication. Large doses of alcohol cause the
condition known as
drunkenness, or in-
toxication, a term
which comes from
the word " toxic,"
meaning "poison."
The effect of wine
seen at a social
dinner where those
who have taken
moderate amounts
begin to grow talk-
ative, excitable, and
hilarious, repre-
sents a pathologi-
cal state of the
nervous system;
that is, a disturb-
ance of the natural
conditions of the
body. Such a per-
son is poisoned,

FIG. 125. Trunk of the Left Pneumogastric.

even though he is (Showin& its distribution by its branches and ganglia to
the larynx, pharynx, heart, lungs, and other parts.)

only in the first

stage of intoxication, which is that of mental excitement.
There is no precise boundary between the quantity which
produces the first and that which produces the second,

the taste for the classics, and the finer mental pleasures throughout broad
parts of the nation, and in both sexes, to an extent that makes one cry for
help. Among the academic youth of Germany the drinking of beer has
truly killed the ideals and the ethics and has produced an incredible
vulgarity."

232 Life and Health

that is, the stage of unsteadiness of muscle ; nor between
that which causes the second and that which eventuates
in the third, the stage of drunkenness.

353. The Effects of the Habitual Use of Alcohol upon
the Brain. The effects of the habitual use of alcohol on
the substance of the brain itself have been studied by
means of high-power microscopes and staining methods,
which show actual changes in the brain cells caused by
frequent contact with alcohol. The fine granular struc-
tures on the outer branches and twigs of the nerve cells
soften and swell and appear to run together in small
masses, causing local coarseness.

These changes in the cells whose function is the evo-
lution of thought make the brain slower in receiving
impressions, because the fine structures thus changed are
concerned in the formation and association of images.
This is also verified in real life, where changes in mental
power and in moral character keep pace with the increasing
indulgence of the drinker.

354. The Power of Self -Control weakened by Alcohol.
The effect of even a small amount of alcohol upon the
brain is shown by its action in weakening the power of
self-control. No one can tell, if he begins to drink, how
many indulgences in even a moderate amount of alcohol
may make him the victim of an overmastering alcoholic
appetite. A single glass, in the case of a person who has
at any previous time been overcome by such an appetite,
may at once, for the time being, take away his self-control.
It is the general testimony of such men that if they take
but one glass of any alcoholic liquor, their power of further
resistance is destroyed. It is not that such men had in
the beginning less power of self-control, but that alcohol
weakens the will by its effect upon the nervous system.

The Nervous System 233

355. Evil Results of Alcoholism inherited. Children may
inherit from drinking parents a disordered nervous sys-
tem which makes them more liable to acquire a craving
for strong drink. Careful statistics of a large number
of families descended from drunkards show that a large
proportion of them give undoubted proof of well-marked
hereditary neuroses, i.e., diseases of the nervous system.
This heredity is proved by the unusual prevalence in such
families of infant mortality, convulsions, epilepsy, hysteria,
obscure brain diseases, and imbecility.1

356. Opium and its Common Forms. Opium is a gum-
like substance, the dried juice of the unripe capsule of a
variety of poppy which is grown chiefly in Asia Minor and
India. It is usually seen as a powder of a yellowish-brown
color.

Morphine, a white powder, is a very condensed form of
opium. Laudanum is an alcoholic solution of opium.
Paregoric is a diluted and flavored form of an alcoholic
tincture of opium.

357. Poisonous Effects of Opium. Opium is often used
solely for its narcotic and intoxicating influence. The drug
thus used lays its benumbing hand upon the brain. The
mind is befogged ; thought and reasoning are dulled.

The moral sense after a time may become benumbed ;
persons once honest resort to fraud and theft, if need be,
to obtain the drug, till at last health, character, and life
itself all become a pitiful wreck.

1 After careful examination of the whole question, physiologists — and
among physiologists I include those who maintain alcohol may be useful,
as well as those who hold that it is harmful — have come to the conclusion
that the principal action of alcohol is to blunt sensation, and to remove
what we may call the power of inhibition by blunting the higher centers of
the brain. — DR. G. SIMS WOODHEAD, Professor of Pathology in Cambridge
University, England.

234 Life and Health

358. The Victim of the Opium Habit. Occasionally per-
sons convalescing from serious sickness in which anodynes
were taken unwisely cling to them long after recovery.
Other persons, jaded with business or with worry, and
unable to sleep, unwisely resort to some narcotic mixture
to procure rest. In these and other similar cases the use
of opiates is always most pernicious. The amount must
be steadily increased to obtain the desired repose.

Even if the desired sleep is procured, it is hardly the cov-
eted rest, but a troubled and dreamy slumber, leaving the
body in the morning quite unrefreshed, the head aching,
the mouth dry, and the stomach devoid of appetite. But
far worse than even this condition may be the opium habit,
which soon becomes a bondage in which life is shorn of its
wholesome pleasures, and existence becomes a burden.

359. Chloral. Chloral is a powerful drug that has been
much resorted to by unthinking persons to produce sleep.
Others, yielding to a morbid reluctance to face the prob-
lems of life, have sought shelter in artificial forgetfulness.
The chloral habit is a source of great danger and is difficult
to cure.

360. Ether and Chloroform. Ether and chloroform, those
priceless blessings to the human race if properly bestowed,
may become instruments of death when carelessly trifled
with. Persons who have been accustomed to inhale the
vapor in slight whiffs for neuralgia or similar troubles do
so at great peril, especially if lying down. They are liable
to become slowly unconscious, and so to continue the
inhalation till life is ended.

361. Other Powerful Drugs. There is still another class
of drugs, often carelessly used, whose effect, while less
directly serious than those mentioned, is yet far from
harmless. They have sprung into popular use since the

The Nervous System 235

disease la grippe began its dreaded career, and include
phenacetin, antipyrine, antifebrine, and many other similar
preparations.

The popular use of the narcotic drug known as cocaine
is beset with danger. The cocaine habit is easily formed,
but difficult to relieve.

These drugs, taken freely and carelessly for all sorts
and conditions of mental and physical ailments, are power-
ful depressants. . They lower the action of the heart and
the tone of the nervous centers.

362. Effect of Tobacco on the Nervous System. The
profound effect of tobacco upon the nervous system is shown
by the distressing prostration and pallor, the dizziness and
faintness, with nausea and vomiting, which follow its use
by the beginner.

The morbid effect of tobacco upon the nervous system of
those who habitually use it is often shown in the irregular
and enfeebled action of the heart, with dizziness and mus-
cular tremor. The character of the pulse may show plainly
the unsteady heart action caused by the partial paralysis
of the nerves controlling this organ.

The nervous breakdown of many men in mature life is
often due to the continued use of this depressing agent.
This is shown more especially in men of sedentary habits.

363. Effects of Tobacco on the Mental Abilities of Young
Men. The mind of the habitual user of tobacco may lose
its capacity for study or successful effort. This is especially
true of the young. The growth and development of the
brain having been once retarded, the youthful user of tobacco
has established a permanent drawback which may hamper
him all his life. The keenness of his mental perception
may be dulled and his ability to seize and hold an abstract
thought may be impaired.

236 Life and Health

The honors of the great schools, academies, and colleges
are very largely taken by the abstainers from tobacco. This
is proved by the result of repeated and extensive compari-
sons of the advanced classes in a great number of institu-
tions in this country and in Europe. Our military and
naval academies and very many seminaries and colleges
very properly prohibit the use of tobacco by their "students.
The laws of many states rigidly forbid the sale of tobacco,
especially of cigarettes, to minors. \ L—

ADDITIONAL EXPERIMENTS

Experiment 98. To illustrate the cooperation of certain parts of
the body. Tickle the inside of the nose with a feather. This does
not interfere with the muscles of breathing, but by reflex action they
'come to the help of the irritated part and provoke sneezing to clear
and protect the nose.

Experiment 99. Pretend to aim a blow at a person's eye. Even
if he is warned beforehand, the lids will close in spite of his effort to
prevent them.

Experiment 100. To illustrate how sensations are referred to the
ends of the nerves. Strike the elbow end of the ulna, where the
ulnar nerve is exposed, against anything hard (commonly called
" hitting the crazy bone "), and the little finger and the ring finger
will tingle and become numb.

Experiment 101. To show that every nerve is independent of any
other. Press two fingers closely together. Let the point of the finest
needle be carried ever so lightly across from one finger to another,
and we can easily tell just when the needle leaves one finger and
touches the other.

Experiment 102. To paralyze a nerve temporarily. Throw one
arm over the sharp edge of a chair back, bringing the inner edge of
the biceps directly over the edge of the chair. Press deep and hard
for a few minutes. The deep pressure on the nerve of the arm will
put the arm "asleep," causing numbness and tingling. The leg and
foot often fall " asleep " by deep pressure on the nerves of the thigh.

CHAPTER XI
THE SPECIAL SENSES

364. The Special Senses. The senses are the avenues by
which we obtain information concerning our bodily condi-
tion and the world around us.

In a general way, our senses may be compared to a cer-
tain number of disciplined picket-guards, along the outposts
of the mind, whose business it is to take note of events
and to report to headquarters any information which may
be within the range of their duty.

In other words, we are provided with special senses, or
"five gateways of knowledge," as they are often called,
by means of which information is given us regarding out-
ward forces and objects.

These special senses are touch, taste, smell, sight, and
hearing, to which may be added the muscular sense and a
sense of temperature.

365. General Sensations. The body, as we have learned,
is made up of a great number of complicated organs, each
doing its own part of the general work required for the
welfare of the bodily structure. Through the agency
of the nervous system each of these organs is desig-
nated to work in harmony with the others for the good
of the whole. Now we must have some means of know-
ing whether this harmony is maintained, and of receiving
timely warning if any organ fails to do its particular
duty.

237

238 Life and Health

Such information is supplied by the general sensations.
Thus we have a feeling of hunger or thirst, indicating the
need of food, and a feeling of discomfort when imperfectly
clad, warning us of the need of more clothing. To these
may be added the sensations of pain, tickling, and itching.

The great majority of sensations result from some outward
stimulus or agency ; and yet some sensations, such as those
of faintness, restlessness, and fatigue, seem to spring up
within us in some mysterious way, without any obvious
cause.

366. Essentials of a Sense Organ. Certain conditions are
necessary for a sensation. First, there is a special structure
adapted to a particular kind of influence. Thus the ear is
formed specially for being stimulated by the waves of sound,
while the eye is not influenced by sound, but responds to
the action of light. These special structures are called
terminal organs.

Again, a nerve proceeds from the special structure, and provides
direct communication with nerve cells in the brain in the region of
consciousness. This last point is important to remember,
for if for any reason the impression is arrested in the
connecting nerve, no sensation will result. Thus a man
whose spine has been injured may not feel a severe pinch
on either leg. The impression may be sufficient to produce
as marked a reflex act as in a person with a healthy cord,
but the man thus hurt does not feel the pinch, because
the injury has prevented the impression from being carried
up the cord to the higher centers in the brain.
J 367. The Condition of Sensation. It is thus evident that
while an impression may be made upon a terminal organ, it
cannot strictly be called a sensation until the person becomes
conscious of it. The consciousness of an impression is, therefore,
the essential element of a sensation.

The Special Senses 239

It follows that sensation may be prevented in various
ways. In the sense of sight, for example, one person may
be blind because the terminal organ, or eye, is defective or
diseased. Another may have perfect eyes and yet have no
sight, because a tumor presses on the nerve between the
eye and the brain. In this case the impression fails because
of the break in the communication. Once more, the eye
may be perfect and the nerve connection unbroken, and yet
the person cannot see, because the center in the brain itself
is injured from disease or accident and cannot receive the
impression.

368. The Functions of the Brain Center in the Perception
of an Impression. Sensation is really the result of a change
which occurs in a nerve center in the brain, and yet we refer
sensations to the various terminal organs. Thus, when
the skin is pinched, the sensation is referred to the skin,
although the perception is in the brain. We may think it
is the eyes that see objects ; in reality, it is only the brain
that takes note of them.

This is largely the result of education and habit. Thus,
from the effects of a blow on the head one often sees flashes
of light (familiarly known as " stars ") as vividly as if torches
actually danced before the eyes. Impressions have reached
the seeing center in the brain from irritation of the optic
nerve, or the center itself may have been irritated, pro-
ducing the same effect as real lights would cause. In this
case, however, knowing the cause of the flashes, the injured
person is able to correct the erroneous conclusion.
^ 369. Organs of Special Sense. The organs of special
sense, the means by which we are brought into relation
with surrounding objects, are usually classed as five in
number (sometimes fancifully called " the five gateways of
knowledge ") : the skin, the chief organ of touch ; the tongue,

240

Life and Health

the chief organ of taste ; the nose, of smell ; the eye, of
sight ; and the ear, of hearing.

370. The Organ of Touch. The organ of touch, or tactile
sensibility, is the most widely extended of all the special
senses, and perhaps the simplest. It is this sense to
which we instinctively appeal to escape from the illusions
into which the other senses may lead us. It has its seat
in the skin all over the body, and in the mucous membrane
at the entrance to various passages. All
parts of the body, however, have not this
sense in an equal degree.

We learned in Chapter IX that the super-
ficial layer of the skin covers and dips in
between the papillae, which are richly pro-
vided with blood vessels and sensory nerve
fibers. Now many of these nerve fibers
terminate in oval-shaped bodies about one
three-hundredth of an inch long, around
fied View of a Pa- which the nerve fibers wind, and which
pilia of the Skin, they finally enter. These are called touch

with a Touch Cor- Qr ^ CQ Uscle and are found in great

puscle.

numbers on the fingers and toes, and more
scantily in other places, as on the edges of the eyelids
(Figs. 104 and 126).

Again, many of the nerve fibers terminate in corpuscles,
the largest about one-twentieth of an inch long, called
Pacinian corpuscles. These are most numerous in the palm
of the hand and the sole of the* foot.

^ 371. The Sense of Touch. Touch includes the sense of
contact and the sense of pressure. The sense of heat and
cold may be regarded as a distinct sense.

The sense of contact is the most important element in
touch. By it we judge of the form, size, and texture of the

Magni-

The Special Senses 241

surface of the body touched. As we all know, the sense
of touch varies in different parts of the skin. It is most
acute where the outer skin is thinnest. The tips of the
fingers, the edges of the lips, the forehead, and the tip of
the tongue are especially sensitive.

.372. How the Sense of Touch may be educated. The
sense of touch is capable of education and may be devel-
oped to an extraordinary degree in persons who are deprived
of some other special sense, as sight or hearing. We read
of a famous blind sculptor who was said to model excel-
lent likenesses, guided entirely by the sense of touch. An
eminent authority on botany was a blind man, able to dis-
tinguish rare plants by the fingers and by the tip of the
tongue. The blind learn to read with facility by passing
their fingers over raised letters.

It is impossible to contemplate, even for a moment, the
prominence assigned to the sense of touch in the physical
organism, without being impressed with the manifestations
of design, — the work of an all-wise Creator.

^ Experiment 103. To illustrate how the sense of touch is a matter
of habit or education. Shut both eyes and let a friend run the tips
of your fingers, first lightly, over a hard plane surface ; then press
hard, then lightly again, and the surface will seem to be concave.

? Experiment 104. Cross the middle finger over the index finger,
roll a small marble between the fingers ; one has a distinct impression
of two marbles. Cross the fingers in the same way and rub the
crossed ends against the point of the nose. A similar illusion is
experienced.

/ Experiment 105. To test the sense of locality. Ask a person to
shut his eyes, touch some part of his body lightly with the point of
a pin, then remove it, and ask him to indicate the part touched.

0 373. Muscular Sense. When a heavy object is laid upon
' certain parts of the body it produces a sensation of pressure.

242 Life and Health

By it we are enabled to estimate differences of weight. If
an attempt be made to raise this object, it offers resistance,
which the muscles must overcome. The feeling of effort
accompanying an action is known as the muscular sense. It
depends on sensory nerves in the muscles, which carry
impressions from them to the nerve centers.
^ 374. Sense of Temperature. The skin also judges, to
a certain extent, of heat and cold. These sensations can be
felt only by the skin and the mucous membrane at the
entrance to various passages. Direct irritation of a nerve
does not give rise to them. Thus, the exposed pulp of
a diseased tooth, when irritated by cold fluids, gives rise,
not to a sensation of heat or cold, but simply to pain.
Various portions of the body have different degrees of
sensibility. The hand will bear a degree of heat which
would cause pain to some other parts of the body.
i 375. Sense of Pain. The sense of pain is due to an
excessive stimulation of the sensory nerves, and in it all
finer sensations are lost. Thus, when a piece of hot iron
burns the hand, the sensation is the same as when the iron
is very cold. Extreme cold feels like intense heat.
J 376. The Tongue as an Organ of Taste. The sense of
taste is located chiefly in the tongue but may also be
referred even to the region of the fauces. Taste, like
touch, has its seat in special nerve endings.

The tongue is a muscular organ, covered with mucous
membrane, and is richly supplied with blood vessels and
nerves. It is an important factor in chewing, in swallow-
ing, and in articulation.

The surface of the tongue is nearly covered with irreg-
ular projections called filiform papillae, — fine, thread-like
processes, about one-twelfth of an inch high. Interspersed
with these are the fungiform papillae. These are shaped

The Special Senses

243

something like a puffball fungus and may often be detected
by their bright red points when the rest of the tongue
is coated.

Towards the root of the tongue is another kind of
papillae, the circum-
vallate, eight to
fifteen in number,
arranged in the
form of the letter
V, with the apex
directed back-
wards.

In many of the
papillae are peculiar
structures called
taste buds or taste
goblets. These exist
in great numbers
and are believed to
be connected with
nerve fibers. These
taste buds are
readily excited by
savory substances

and transmit the

FIG. 127. The Tongue.

impression along ^ epiglottis . 5, glands at the base of tongue; C, tonsil;
the nerves of taste. V% median, circumvallate papilla; E, circumvallate
•-pi . • papillae; F, filiform papillae; H, furrows on border

of the tongue ; K, fungif orm papilla;.

supplied with sen-
sory nerve fibers which confer taste on the front and on
the back part. Nerve branches also pass to the soft palate
and neighboring parts and confer taste on them to a limited
extent.

244 Life and Health

^ 377. The Sense of Taste. The sense of taste is excited
by stimulation of the mucous membrane of the tongue
and of the palate, affecting the ends of the nerve fibers.
Taste is most acute in or near the circumvallate papillae.
The middle of the tongue is scarcely sensitive to taste, while
the edges and the tip are, as a rule, highly sensitive.

Certain conditions are necessary that the sense of taste
may be excited. First, the substance to be tasted must
be in solution, or be soluble in the fluids of the mouth.
Insoluble substances are tasteless. If we touch our tongue
to a piece of rock crystal, there is a sensation of contact or
cold, but no sense of taste. On the other hand, when we
bring the tongue in contact with a piece of rock salt we
experience the sensations of contact, coolness, and saline
taste.

Again, the mucous membrane of the mouth must be
moist. When the mouth is dry and receives substances
not already in solution there is no saliva ready to dissolve
them ; hence they are tasteless. This absence of taste is
common with the parched mouth during a fever.

Experiment 106. Put a drop of vinegar on a friend's tongue, or on
your own. Notice how the papillae of the tongue start up.

Experiment 107. Rub different parts of the tongue with the pointed
end of a piece of salt or gum aloes, to show that the back of the tongue
is most sensitive to salt and bitter substances.

Experiment 108. Repeat the same w:th some sweet or sour sub-
stance, to show that the edges of the tongue are the most sensitive to
these substances.

Experiment 109. We often fail to distinguish between the sense of
taste and that of smell. Chew some pure, roasted coffee, and it seems
to have a distinct taste. Pinch the nose hard while chewing it, and
there is little taste. Coffee has a powerful odor, but only a feeble
taste. The same is true of garlic, onions, and various spices.

The Special Senses 245

378. Modifications of the Sense of Taste. Taste is modi-
fied to a great extent by habit, education, and many other
circumstances. Articles of food that are unpleasant in
early life often become agreeable in later years. The most
savory dishes may excite disgust, while the simplest articles
may have a delicious flavor to one long deprived of them.
The taste for certain articles is certainly acquired. This
is often true of raw tomatoes and olives.

The organs of taste and smell may be regarded as neces-
sary accessories of the general apparatus of nutrition and are,
therefore, more or less essential to the maintenance of
animal life. While taste and smell are generally main-
tained until the close of life, sight and hearing are often
impaired by time and may be altogether destroyed in
extreme old age.

Experiment no. Light helps the sense of taste. Shut the eyes,
and palatable foods taste insipid. Pinch the nose," close the eyes,
and see how palatable one-half of a teaspoonful of cod-liver oil
becomes.

Experiment in. Close the nostrils, shut the eyes, and attempt to
distinguish by taste alone between a slice of an apple and one of a
potato.

379. Effect of Tobacco and Alcohol upon Taste. Alcoholic
liquors and tobacco tend to impair the delicate sensibility
of the tender papillae of the tongue. The keen appreciation
of fine flavors is destroyed. The once clear and enjoyable
taste for plainly cooked foods is diminished. Highly spiced
and seasoned articles of diet are craved, indulgence in
which usually results in various forms of indigestion.

380. Smell. The sense of smell is lodged in the delicate
membrane which lines the nasal cavities. Man, in common
with all air-breathing animals, has two nasal cavities. They
communicate with the outer air by two nostrils opening in

246 Life and Health

front, while two other passages open into the pharynx
behind.

To increase the area of the air passages the two light,
spongy turbinated bones, one on each side, form narrow,
winding channels. The mucous membrane, with the
branches of the olfactory nerve, lines the dividing wall
and the inner surfaces of these winding passages.

381. The Sense of Smell. The sense of smell is excited
by the contact of odorous particles contained in the air
with the fibers of the olfactory nerves, which are distributed
over the delicate surface of the upper parts of the nasal
cavities.

In ordinary quiet breathing, the air simply flows along the
lower nasal passages into the pharynx, scarcely entering the
olfactory chamber at all. This is the reason why, when we
wish to perceive a faint odor, we sniff up the air sharply.

The delicacy of the sense of smell varies greatly in dif-
ferent individuals and in different animals. It is generally
more acute in savage races. Many animals are more highly
endowed with this sense than is man. The dog appears to
depend on the sense of smell almost as much as on sight.
Deer, wild horses, and antelopes probably surpass all other
animals in vividness of the sense of smell.

382. Association of Smell and Taste. Smell has been
denned as "taste at a distance," and it is obvious that
these two senses not only form a natural group, but are
clearly associated in their physical action, especially in
connection with the perception of the flavor of food. The
sense of odor gives us information as to the quality of food
and drink, and more especially as to the quality of the air
we breathe.

Taste is at the gateway of the alimentary canal, while
smell acts as the sentinel of the respiratory tract. Just as

The Special Senses

247

taste and flavor influence nutrition by affecting the digestive
process, so the various odors about us have an important
bearing upon respiration.

/^383. The Marvelous Sense of Sight. Sight is well
regarded as the highest and the most perfect of all our
senses. It plays so com-
mon a part in our daily
lives that we scarcely
appreciate the marvelous
gift. Sight is essential not
only to the simplest mat-
ters of daily comfort and
necessity, but is also of
prime importance in the
culture of the mind and
in the higher forms of
pleasure. It opens to us
the widest and the most

varied range of observa- FIG. 128. Distribution of Nerves over the

Interior of the Nostrils. (Outer wall.)

A, branches of the nerves of smell, — olfactory
nerve, or ganglion ; B, nerves of common
sensation to the nostrils ; E, F, G, nerves
to the palate springing from a ganglion at
C; //, vidian nerve, from which branches
Z>, 7, and / spring to be distributed to the
nostrils.

tion and enjoyment.

Unlike the senses of
taste and smell, the sense
of vision seems to make us
aware of the existence of
objects which are entirely
apart from us and have no direct or material link connect-
ing them with our bodies.

4 384. The Eye. Apart from its uses, the eye itself is an
interesting and instructive object of study. It presents
beyond comparison the most beautiful example of design
and artistic workmanship to be found in the bodily structure.
It is the watchful sentinel and investigator of the external
world.

248 Life and Health

All the parts of this most wonderful and ingenious
machine are arranged with such a delicate adjustment to
one another, and such an exquisite adaptation of every
part to the great object of the whole, that the eye is
properly regarded as one of the wonders of nature.

385. The Eyeball and the Orbit. The eyeball is nearly
spherical in shape, but is slightly elongated from before
backwards. The front part is clear and transparent and
bulges somewhat prominently to allow the entrance of the
rays of light.

The eye rests in a bowl- shaped socket called the orbit,
formed by parts of various bones of the head and face.
The margins of this cavity are formed of strong bone
which can withstand heavy blows.

The socket is padded with loose, fatty tissue, which
serves as a soft and yielding bed in which the eyeball can
rest and move without injury. In a severe sickness this
fatty tissue is absorbed, and this fact explains the sunken
appearance of the eyes. The eye is bathed with a watery
fluid and protected by the eyelids and the eyebrows ; it is
moved in various directions by muscles, all of which will
be described later.

| 386. The Optic Nerve. The orbit is pierced through its
posterior surface by an opening through which the nerve
of sight, the optic, passes to the eyeball. We may think
of the optic nerve holding the eyeball much as the stem
holds the apple. It is the function of this most important
nerve to transmit impressions of light to the seat of con-
sciousness in the brain, where they are interpreted.
\ 387. The Coats of the Eyeball. The eyeball proper is
composed of three coats, or layers, each of which performs
important functions. These coats are the sclerotic, the
choroid, and the retina.

The Special Senses

249

388. The Sclerotic Coat. The sclerotic coat is the outside
layer and enclosing membrane of the eyeball. It is a tough •
fibrous coat for the protection and maintenance of the
shape of the eye. It is white and glistening in appear-
ance ; the part of it which is visible is known as " the white

SUPERIOR REGIUS

CILIARY PROCESSES
SUSPENSORY LIGAMENT

SUSPENSORY LIGAMENT
CILIARY PROCESSES

OPTIC NER\E

CHOROID

-INFERIOR RECTIIJ.

FIG. 129. Section of the Human Eye.

of tne eye." To this coat, which serves as a kind of
framework for the eye, are attached the muscles which
move the eyeball.

389. The Cornea. In front of the globe the sclerotic
passes into a transparent circular portion forming a kind of
window, through which one can see into the interior. This
is the cornea, a clear, transparent, circular disk, which fits

250 Life and Health

into the sclerotic, somewhat as the crystal fits into the
metallic case of a watch, forming a covering for its dial.
It projects from the general surface of the eyeball, not
unlike a rounded bay window, and is often spoken of as
the " window of the eye."

390. The Choroid Coat. Lining the inner surface of the
sclerotic is the second coat, the choroid, which is made up
almost entirely of blood vessels and nerves. As the choroid
approaches the front part of the eyeball its parts become
folded upon themselves into a series of ridges, called ciliary
processes. These folds gradually become larger and at last
merge into the ciliary or accommodation muscle of the eye.
391. The Iris and Pupil. The circular space thus left

front by the termination of the choroid is occupied by
the iris, a thin circular curtain, suspended in the aqueous
humor behind the cornea and in front of the crystalline lens.

In the center of the iris is a round opening for the
admission of light. This is the pupil, which appears as if
it were a black spot. It seems to be black, just as the
open doorway to a dark closet seems black. The back of
the iris is lined with dark pigment. The color of the iris
varies with the quantity of this pigment, being darker when
the coloring matter is abundant. This pigment layer and
that of the choroid and retina absorb the light entering
the eye, so that little is reflected.

-V 392. The Retina. The third and innermost coat of the
eyeball is the retina, upon which the images of external
objects are received. It lines all but the extreme front of
the inner surface of the posterior chamber.

The retina is a very thin, delicate membrane which forms
the terminal organ of vision. It is really an expansion of the
ultimate fibers of the optic nerve, by means of which
impressions are sent to the brain.

The Special Senses

251

OBJECT

EYE

393. Inner Structure of the Eye. Let us imagine an
eyeball divided through the middle from above downwards.
Let us now start in front and observe its parts. We come
first to the cornea,
which has just
been described
(Fig. 129). The

iris forms a sort 1Ncnvt \\\ CHAMBER
of partition, divid-
ing the cavity of

the eyeball into FIG. 130. Diagram illustrating the Manner in which

two chambers tne Ima§e °f an Object is brought to a Focus on

,-r,, the Retina.

1 he anterior

chamber occupies the space between the cornea and the
iris. It is filled with a thin, watery fluid called the aqueous
humor.

Experiment 112. The retina is not sensitive where the optic nerve
enters the eyeball. This is called the "blind spot." Put two ink
bottles, about two feet apart, on a table covered with white paper.
Close the left eye and fix the right steadily on the left-hand inkstand,
gradually varying the distance from the eye to the ink bottle. At a
certain distance the right-hand bottle will disappear, but nearer or
farther than that, it will be plainly seen.

Experiment 113. Close one eye and look steadily at the small a in
the figure below. The other letters will also be visible at the same
time. If now the page be brought slowly nearer to the eye, while the
eye is kept steadily looking at the small a, the large A will disappear
at a certain point, reappearing when the book is brought still nearer.

oAx

On the reappearance of the A it will be noted that it comes into view
from the inner side, the x being seen before it. If now we move the
book back towards its original place, the A will again disappear, com-
ing again into view from the outer side when the o is seen before it.

252 Life and Health

The portion behind the iris forms the posterior chamber
and contains the crystalline lens and the vitreous humor.

The vitreous humor fills about four-fifths of the eyeball,
and serves to hold the choroid and the retina in position
and to maintain the proper relations of the inner structures
of the eye.

The iris consists of a framework of connective tissue, the
surface of which is lined by cells containing pigment, which
gives color to the eye. Bundles of involuntary muscular
fibers are found in the substance of the iris, which are
arranged to allow the pupil to contract or dilate more or
less widely.

* 394. The Crystalline Lens. Just behind the pupil and
close to the iris is a semisolid, doubly convex body, called
the crystalline lens. It is shaped like a magnifying glass,
convex on each side, but with the posterior surface more
convex than the anterior. In health it is perfectly clear and
transparent, and highly elastic. When the lens becomes
opaque, from change in old age, or from ulcers or wounds,
we have the disease known as cataract.

The crystalline lens is not placed loosely in the eyeball,
but is enclosed in a transparent and elastic capsule sus-
pended throughout its circumference by a ligament called
the suspensory ligament. This ligament not only retains the
lens in place, but is capable of altering its shape.
V 395. The Ciliary Muscle. All around the edge, where
the cornea, sclerotic, and choroid meet, is a ring of invol-
untary muscular fibers, forming the ciliary muscle. When
these fibers contract, they draw forwards the attachment
of the suspensory ligament of the lens, the pressure of
which on the lens is consequently diminished. The elas-
ticity of the lens causes it at once to bulge forwards, and
it becomes more convex.

The Special Senses

253

The ciliary muscle is thus known as the muscle of accom-
modation, because it has the power to accommodate the eye
to near and distant objects. In this respect it corresponds
in its use to the adjusting screw in the opera glass and the
^microscope.

396. The Refractive Media of the Eye. The eye is a
closed chamber, into which no light can pass except through

FIG. 131. Diagram showing the Change in the Lens during
Accommodation.

(On the right the lens is arranged for distant vision, the ciliary muscle is relaxed,
and the ligament D is tense, so flattening by its compression the front of
the lens C; on the left the muscle A is acting, and this relaxes the ligament
and allows the lens B to become more convex, and so fitted for the vision
of near objects.) *

the cornea. All the rays that enter the eye must also
pass through the crystalline lens, which brings them to
a focus as would an ordinary lens.

Now, if the media through which the light from an
object passes to reach the retina were all of the same
density as the air, and were also plane surfaces, an
impression would be produced, but the image would not
be distinct.

The action of the crystalline lens is aided by several
refractive media in the eye. These media are the cornea,
the aqueous humor, and the vitreous, humor. By reason
of their shape and density these media refract the rays of
light, and bring them to a focus upon the retina, thus

254 Life and Health

aiding in producing a sharp and distinct image of the
object. Each point of the image, being the focus or
meeting place of a vast number of rays coming from the
corresponding point of the object, is sufficiently bright to
stimulate the retina to action.

Thus, the moment rays of light enter the eye they are
bent out of their course. By the action of the crystalline
lens in altering its convexity so that the eye is capable of
adjusting itself to different distances, and aided by the
refractive media, the rays of light that are parallel when
they fall upon the normal eye are brought to a focus on
the retina.

Experiment 114. With a hand mirror reflect the sunlight on a
white wall. Look steadily at the spot for a full minute, and then let
the mirror suddenly be removed. The "complementary" color — a
dark spot — will appear.

Experiment 115. To show that impressions made upon the retina
do not disappear at once. Look steadily at a bright light for a
moment or two, and then turn away suddenly, or shut the eyes.
A gleam of light will be seen for a second or two.

Look steadily at a well-lighted window for a few seconds, and then
turn the eyes suddenly to a darkened wall. The window frame may
be plainly seen for a moment.

Experiment 116. Take a round piece of white cardboard the size
of a saucer, and paint it in alternate rings of red and yellow, — two
primary colors. Thrust a pin through the center and rotate it rapidly.
The eye perceives neither color, but orange, — the secondary color.

397. Old Sight. " Old sight," known as presbyopia, is
- a common defect of vision in advancing years. This is a
partial loss of the power to accommodate the eye to differ-
ent distances. This defect is caused by an increase in the
density of the crystalline lens, and an accompanying dimi-
nution in the ability to change its form. The far point of

The Special Senses 255

vision is not changed, but the near point is removed so far
from the eye that near objects are no longer visible.

Hence, when a person about forty-five years of age com-
plains of dim light, poor print, and tired eyes, the time has
come to seek the advice of an oculist. A convex lens
may be needed to aid the failing power to increase the con-
vexity of the lens, and to assist it in bringing the divergent
rays of light to a focus.

-\ 398. Long or Far Sight. In "long sight," or hyperme-
tropia, both the near and far point of vision are concerned,
and there is no distinct
vision at any distance
without a strain. It is
a defect in the focus,
dependent upon the form
of the eyes, and often .

* FIG. 132. Diagram illustrating the Hyper-

existS in childhood. The metropic (Farsighted) Eye.

axis of the eyeball is too The image P/ of a point /> falls behind the

Short, and the foCUS falls retina in the unaccommodated eye. By

, 11 • t, • t, means of a convex lens (Z,) it may be focused

beyond the retina, WhlCh On the retina without accommodation (dotted

is tOO near the Cornea. lines). (To save space P is placed much

T i -i 11 j ...I. • • to° near the eye.)

In childhood this strain

may pass unnoticed, but sooner or later it manifests itself
by a sense of fatigue, dizziness, and a blurred and indistinct
vision. The remedy is in the use of convex glasses to
converge parallel rays of light before they enter the eye.
The muscles of accommodation are thus relieved of their
extra work.

^, 399. Short or Near Sight. "Short sight," known as
myopia, is one of the commonest defects of vision. In this
defect the axis of the eye, or the distance between the
cornea and the retina, is too long and the rays of light are
brought to a focus in front of the retina. The tendency

256

Life and Health

to shortsightedness exists in many cases at birth, and is
largely hereditary. It is alarmingly common with those

who make a severe
demand upon the eyes.

During childhood there
is a marked increase of
nearsightedness. The
results of imprudence and

FIG. 133. Diagram illustrating the
Myopic (Nearsighted) Eye.

abuse, in matters of eye-
sight, are so disastrous,

The image P' of a distant point P falls in especially during School

front of the retina even without accommo- Rf ^ the tion f

dation. By means of a concave lens (/,)

the image may be made to fall on the retina short sight becomes One

(dotted lines). (To save space /» is placed of much importance,
much too near the eye.) . r

Nearsightedness often

demands skillful advice and careful treatment. Concave
glasses, properly adjusted to meet the conditions of the
eyes, may be needed.

Experiment 117. To note the shadows cast upon the retina by
opaque matters in the vitreous humor (popularly known as floating
specks, or gossamer threads}, look through a small pinhole in a card
at a bright light covered by a ground-glass shade.

-/•Experiment 118. To illustrate accommodation. Standing near a
source of light, close one eye, hold up both forefingers not quite in a
line, keeping one finger about six or seven inches from the other eye,
and the other forefinger about sixteen to eighteen inches from the eye.
Look at the near finger ; a distinct image is obtained of it, while the
far one is blurred or indistinct. Look at the far image ; it becomes
distinct, while the near one becomes blurred. Observe that in accom-
modating for the near object, one is conscious of a distinct effort.

v 400. Astigmatism. There is an optical condition of the
eye known as astigmatism, in which the cornea is usually at
fault. In this defect of vision the curvature of the cornea

The Special Senses

257

is greater in one meridian than in another. As a result,
the rays from an object are not all brought to the same
focus. Objects appear distorted or are seen with unequal
clearness.

Glasses of a peculiar shape are required to counteract
this defect.

4- 401, The Movements of the Eyes. The mechanical
arrangement by which the eyeballs are moved in different

FIG. 134. Muscles of the Eyeball.

A, attachment of tendon connected with the four recti muscles ; B, external
rectus, divided and turned downward, to expose the internal rectus;
C, inferior rectus ; £>, internal rectus ; E, superior rectus ; F, superior
oblique ; H, pulley and reflected portion of the superior oblique ; K, inferior
oblique; L, levator palpebri superioris ; M, middle portion of the same
muscle (L).

directions is quite simple. It is done by six little mus-
cles, arranged in three pairs. Four of these muscles run
a straight course and are called the recti. The remaining
two muscles bend in their course and are called oblique.
The coordination of these tiny muscles is marvelous in its
delicacy, accuracy, and rapidity of action.

258 Life and Health

Thus the beauty of the internal mechanism of the eye
has its fitting complement in the precision, delicacy, and
range of movement conferred upon it by its muscles.

402. StraSbismus. When, for any cause, the coordi-
nation is faulty, "cross-eye," technically called strabismus,
is produced. Thus, if the internal rectus is shortened, the
eye turns in ; if the external rectus, the eye turns out,
producing what is known as " wall-eye."
\ 403. The Eyelids. The eyelids, two in number, move over
the front of the eyeball and protect it from injury. They
consist of folds of skin lined with mucous membrane, kept in
shape by a layer of fibrous material. Near the inner surface
of the lids is a row of glands, known as the Meibomian
glands, which open on the free edges of each lid (Fig. 137).

The inner lining membrane of the eyelids is known as
the conjunctiva ; it is richly supplied with blood vessels and
nerves. After lining the lids it is reflected on to the eye-
balls. Jt is this membrane which is occasionally inflamed
from taking cold.

\ 404. The Eyelashes and Eyebrows. The free edges of
the lids are bordered with two or more rows of hairs called
the eyelashes, which serve to protect the eyes from dust,
and to a certain extent to shade them. Their loss gives a
peculiar, unsightly look to the face.

The upper border of the orbit is provided with a fringe of
short, stiff hairs, the eyebrows. They help to shade the eyes
from excessive light, and to protect the eyelids from
perspiration, which would otherwise cause discomfort.
> 405. The Lachrymal Apparatus. Nature provides a spe-
cial secretion, the tears, to moisten and protect the eye.
The apparatus producing this secretion consists of the
lachrymal or tear gland and lachrymal canals or tear passages
(Figs. 135 and 137).

The Special Senses

259

Outside of the eyeball, in the loose, fatty tissue of the
orbit, in the upper and outer corner, is the lachrymal or tear
gland. It is about the size of a small almond, and from it
lead several little canals which open on the inner surface
of the upper lid.

The fluid from the gland flows out by these openings
over the eyeball, and is collected at the inner or nasal
corner. Here in each lid is
a little reddish elevation, or
lachrymal caruncle, in which
is an opening, communicating
with a small canal in the lid
which joins the lachrymal sac,
lodged between the orbit
and the bridge of the nose

(Fig. 137).

406, The Nasal Duct.

From the lachrymal sac there
passes a channel, the nasal
duct, about one-half of an
inch long, leading into the

lower portion of the nOStril. A, lachrymal gland, the size of a small

The fluid which has flowed fa^tD^^A^t^,^^

Over the eye is drained Off ducts, which form a row of openings

by these canals into the nose. into the conJunctival fold-
During sleep this secretion is much diminished. When the
eyes are open the quantity is sufficient to moisten the eye-
ball, the excess being carried into the nose so gradually
that the attention is not attracted to it.

The flow of the tears into the nose may be blocked by
inflammation of the nasal duct. The fluid collects in the
corners of the eyelids and overflows down the cheeks,
producing much discomfort.

FIG. 135. Lachrymal Gland and
Ducts.

260 Life and Health

\g 407. The Tears. If the eyelids are irritated the sensory
nerves are stimulated and the impression is carried to the
brain. Thence the nerve impulses travel
to the lachrymal glands, leading to an
increased flow of their secretion. Thus
the irritation of the sensory nerves in
the nasal passages by smelling such
substances as onions, or pungent salts,
may cause a copious flow of tears.

Various emotions, as joy and grief,
may produce similar results. In these
cases the glands secrete the fluid in
such quantities that it cannot escape

FIG. 136. Lachrymal , ., , , , , . .

Canals, Lachrymal b7 the lachrymal canals, and the excess

Sac, and Nasal Duct, rolls over the cheeks as tears. Exces-

opened by their Ante- sive grief sometimes acts on the nerve

centers in exactly the opposite manner,

so that the activity of the glands is arrested and less fluid

is secreted. This is the reason why some people do not

shed tears in times of deep grief.

Experiment 119. Gently turn the inner part of your lower eyelid
down. Look in a mirror, and the small lachrymal point, or opening
into the nasal duct, may be observed.

408, Color-Blindness. The power of discriminating be-
tween different colors is impaired in color-blindness. Experi-
ment shows that ninety-six out of every one hundred men
agree as to the identity or the difference of color. The
remaining four show a defective perception of color and are
said to be color-blind.

In its true sense, color-blindness is always congenital, often
hereditary. This condition of abnormal vision is totally in-
curable. A person may be color-blind and not know it until

The Special Senses

261

the defect is accidentally revealed. The common form of
defective color vision is the inability to distinguish between
red and green. This abnormal defect of vision may be a
matter of great practical importance to those employed on
steam and electric railways, on shipboard, and elsewhere.

Experiment 120. To test color-blindness. On no account is the
person being tested to be asked to name a color. In a large class of
students one is pretty sure to find some who are more or less color-
blind. The common defects are red and green.

Place worsteds on a white background in a good light. Select, as
a test color, a skein of light green color, such as would be obtained
by mixing a pure green
with white. Ask the
examinee to select and
pick out from the heap all
those skeins which appear
to him to be of the same
color, whether of lighter
or darker shades. A color-
blind person will select
amongst others some of
the confusion colors, e.g.,
pink, yellow. A colored
plate showing these should FIG. 137. Showing the Relative Position of
be hung up in the room. the Lachrymal Apparatus, the Eyeball, and
Any one who selects all the Eyelids.

the greens and no con- A, lachrymal canals, with the minute orifices repre-
fusion colors has normal sented as two black dots (puncta lacrymalia) to

the right ; £, tendon of the orbicularis palpe-
brarum muscle ; apparently under B is seen the
lachrymal sac. The minute openings of the
Meibomian glands are seen on the free margins
of the eyelids. Below A is seen a small conical
elevation, with black dots (the lachrymal papilla
or caruncle).

color vision. If, however,
one or more confusion
colors be selected, proceed
as follows : select as a
test color a skein of pale

rose. If the person be red
blind, he will choose blue and violet ; if green blind, gray and green.
Select a bright red skein. The red blind will select green and
brown ; the green blind will choose red or lighter brown.

262 Life and Health

409. How the Eyes may be abused in Reading. The bat-
tered type and poor presswork, now so commonly used in
the cheap editions of books and periodicals, are often inju-
rious to the eyesight. The habit of reading, in the cars or
elsewhere, the daily paper and poorly printed books, with
their blurred and indistinct type, is a severe strain on the
eyes. It is a dangerous practice to read in bed at night,
or while lying down in a darkened or shaded room. This is
especially true during recovery from illness.

410. Hints on giving the Eyes Rest. After reading
steadily for some time, the eyes should be rested by clos-
ing them for a short period or by looking at some distant
object, even if only for a few moments. The book, the
sewing, and work generally, should be held as far from the
eyes as is compatible with good vision. The natural tend-
ency is to reverse this rule.

We should never read, write, sew, stitch, or otherwise
use the eyes when they smart or tingle, or when the sight
is dim or blurred. The eyes are then tired and need a rest.
Much injury may be done by reading in twilight, or by
artificial light in the early morning, and by reading and
working in badly lighted and ill-ventilated rooms.

411. Additional Hints on the Care of the Eyes. Good
artificial light is much to be preferred to insufficient sun-
light. The artificial light should be sufficiently bright and
steady ; a flickering light is always bad. Riding against a
strong wind, especially on a bicycle, may prove hurtful, at
least for eyes that are inclined to any kind of inflammation.
The light reflected from snow is a common source of injury
to the eyes.

The eyes should never be rubbed when they are irritated
by any foreign substance. The sooner the offending sub-
stance is removed the better. The Germans have a quaint

The Special Senses 263

proverb that one should never rub his eyes except with
his elbows.

The eyes of young infants should not be exposed to
electric lights or to the direct rays of the sun. Special care
should be taken with children's eyes during and after an
attack of measles and scarlet fever.

Glasses should be worn when they are needed A failure
to do this usually causes much unnecessary suffering. It
is far from wise to postpone as long as possible the first
use of glasses.

412. Effect of Alcohol
and Tobacco upon Vision.

A wide comparison of cases FlG. ,38. The Actual Size of the Test-
by Careful observers proves Type, which should be seen by the
that a large fraction of Normal Eye at a Distance of Twenty

Feet,
those who indulge in

strong drink suffer from some disease of the eye. The
earlier and slighter forms of injury done to the eye by the
use of intoxicants are quite familiar, — the watery condition
of the eye and of the lids, and its red and bleared aspect.
The nerves controlling the circulation of the eye are
partially paralyzed, and thus the relaxed vessels become
distended.

Long use of intoxicants may produce diseases of the
retina, involving, in many cases, marked diminution of
acuteness as well as quickness of vision.

What is known to oculists as "tobacco blindness," and
a temporary form of color-blindness, may result from an
excessive use of tobacco.

The ill effects of tobacco, and especially of cigarettes,
upon the eyes of the young are generally recognized.

413. The Sense of Hearing. The structure of the human
ear is much more complicated than is generally supposed.

264

Life and Health

As a whole, it may be considered a peculiar form of nerve
ending.

The external ear forms only a part of a most elaborate
apparatus whereby sound waves may be transmitted inward
to the real organ of hearing. The really sensitive part of
the ear, in which the auditory nerve ends, is buried for
protection so deep in the bones of the head that sounds

cannot directly affect it.
Some arrangement, there-
fore, is required for con-
ducting the sounds inward
to this organ.

In studying the structure
of the ear we may divide it,
for convenience, into three
parts : the external ear, the
middle ear, and the deeply
placed portion, the inner
ear.

414. The External Ear.
The external ear consists of

FIG. 139. The Pinna, or Auricle.

an expanded portion known
as the pinna, or auricle, and
of a passage, the auditory canal, or meatus, leading inward
from it. The surface of the auricle is convoluted to collect
and transmit the vibrations of air by which sound is pro-
duced. Many animals move the auricle in the direction
of the sound. Thus the horse pricks up its ears when
it hears a noise, the better to judge of the direction of
sounds.1

1 The student who will take a little trouble in noticing the ears of the
persons whom he meets from day to day will be greatly interested and sur-
prised to see how much the auricle varies.

The Special Senses

265

415. The Auditory Canal. The auditory canal, the pas-
sage to the middle ear, conducts the vibrations of sound
to the tympanic membrane. It is about an inch and a
quarter long. Near its outer portion are a number of fine
hairs slanting outwards. These prevent the entrance of
insects. Embedded in the deeper parts of the canal are

FIG. 140. General View of the Organ of Hearing.

A, pinna; B, cavity of the concha, showing the orifices of a great number of
sebaceous glands; C, external auditory meatus; D, membrana tympani;
F, incus; If, malleus; 1C, handle of malleus applied to the internal surface
of the membrana tympani; L, tensor tympani muscle; between M and K
is the tympanic cavity ; N, Eustachian tube ; O, P, semicircular canals ;
R, internal auditory canal; S, large nerve given off from the facial gan-
glion ; T, facial and auditory nerves.

glands which secrete the cerumen, or earwax, which keeps
the canal moist and helps to protect it against foreign
bodies and insects.

416. The Middle Ear. At the inner end of the outer
ear passage is the middle ear or tympanum, or "the drum
of the ear." Stretched at an angle across the deep end
of the passage is a thin oval membrane which completely
closes it.

266 Life and Health

This membrane, the tympanic membrane, or drum mem-
brane, thus forms a partition between the passage of the
outer ear and the cavity of the middle ear. The latter is
a small air chamber in the petrous por-
tion of the temporal bone. On the bony
inner wall of this tympanum are two
openings, the round window, or foramen
rotundum, and the oval window, or fora-
men ovale, which lead into the labyrinth

Fia.4.. Ear Bones.

(Anterior view.) 3417. The Eustachian Tube. The tym-

x, malleus, or hammer; panic cavity communicates with the back

a, incus, or anvil; 3, part of the throat by the Eustachian tube.

stapes, or stirrup. . 1-1 i •

1 his tube is about one and one-halt inches
long and lined with mucous membrane similar to that of the
tympanic chamber and the throat. This passage is usually
closed, but is opened in the act of swallowing.

In health there is no communication between the cham-
ber of the middle ear and the outside, except by the
Eustachian tube. Thus a throat cold, with swelling of
the mucous membrane, is often accompanied with some
degree of deafness, because the swelling may block the
lumpen of the tube and thus prevent the free passage of
the air to and fro.

> 418. The Bones of the Ear. A most curious feature of
the ear is the chain of tiny movable bones which stretch
across the cavity of the middle ear. They connect the
tympanic membrane with the labyrinth and serve to con-
vey the vibrations communicated to the membrane across
the cavity of the tympanum to the internal ear.

These bones are three in number and from their shape
are called the malleus, or hammer ; incus, or anvil ; and
stapes, or stirrup.

The Special Senses 267

These little bones are connected with each other and the
tympanum by ligaments and moved by three tiny muscles.
Two are attached to the hammer and tighten and relax the
drum ; the other is attached to the stirrup and prevents it
from being pushed too deeply into the oval window.

Experiment 121. To 'vibrate the tympanic membrane and the
little ear bones. Shut the mouth and pinch the nose tightly. Try to
force air through the nose. The air dilates the Eustachian tube and
is forced into the ear drum. The distinct crackle, or clicking sound,
is due to the movement of the ear bones and the tympanic membrane.

419. The Internal Ear. The internal ear, one of the
most delicate and complex pieces of mechanism in the
whole body, receives the impression of sound and carries
it directly to the seat of consciousness in the brain.

The internal ear, or labyrinth, consists of three distinct
parts, or variously shaped chambers, hollowed out in the
temporal bone, — the vestibule, the semicir-
cular canals, and the cochlea, or snail's shell
(Figs. 144 and 145).

420. The Vestibule. The vestibule is an
oval-shaped chamber, about one-fifth of an
inch in diameter, occupy-
ing the middle part of the

internal ear. It is on the
inner side of the oval win-
dow, which is closed, as
we have seen, by the stir- FlG- I42- A Cast of

, T^, . , the External Audi- -^sm^^

rupbone. From one side tory Canal. (Posterior view.)
of this vestibule, or cen-
tral hall, the three semicircular canals pass off, and from
the other side the cochlea.

_, 421. The Semicircular Canals. The three semicircular
canals, so called from their shape, are simply bony tubes

268 Life and Health

about one-twentieth of an inch in width, making a curve
of about one-quarter of an inch in diameter. They pass
out from the vestibule, and, after bending around somewhat
like a hoop, return again to the vestibule. Each bony

canal has a swelling at the end
where it opens into the vestibule.
This is called the ampulla.
J422. The Cochlea. The coch-
lea, or snail's shell, is another
chamber hollowed out in the
FIG. 143. Section of Cochlea, solid bone. It is coiled on
(From A straight downwards is the itself somewhat like a snail's
direction of the central column, to shell. There is a central pillar,

which E points. B points to the i • • « • i •

projecting ridge, almost dividing around which winds a long spiral
the canal of the tube into an canal. One passage from the

upper compartment, D. and a ....

lower, c.) cochlea opens directly into the

vestibule ; the other leads to

the chamber of the middle ear and is separated from it by
the little round window already described.

The cochlea contains thousands of the most minute cords,
known as the fibers or organ of Corti. Under the micro-
scope they present the appearance of the keyboard of a
piano. These fibers appear to vibrate in sympathy with the
countless shades of sounds which penetrate the ear. From
the hair-like processes on these tightly stretched fibers,
auditory impulses appear to be transmitted to the brain.
> 423. The Membranous Sac. The tubes and chambers
of the inner ear enclose and protect a delicate membranous
sac of exactly the same shape as themselves. Between the
bony walls of the passages and the membranous bag inside
is a thin, clear fluid, the perilymph. The membranous sac
itself contains a similar fluid, the endolymph. In this fluid
are found some minute crystals of lime, like tiny particles

The Special Senses

269

of sand, called otoliths, or ear stones. Every movement of
the fluid itself throws these grains from side to side.
,-v 424. The Auditory Nerve. The auditory nerve, or nerve
of hearing, passes to the inner ear through a passage in
the solid bone of the skull. Its minute filaments spread at
last over the inner walls of the membranous labyrinth in
two branches. One goes to the vestibule and the ampullae
at the ends of the semicircular canals ; the other leads to
the cochlea.

3 425. Mechanism of Hearing. Waves of sound reach the
ear and are directed by the concha to the external passage,
at the end of which they reach
the tympanic membrane.
When the sound waves beat
upon this thin membrane it is
thrown into vibration, repro-
ducing in its movements the
character of the air vibrations
that have fallen upon it.

The vibrations of the tym-
panic membrane are now passed
along the chain of bones
attached to its inner surface
and reach the stirrup bone.
The stirrup now performs a to-

FIG. 144. Bony Internal Ear of
the Right Side. (Magnified ;
the upper figure of the natural
size.)

and-fro movement at the oval A> ™l window ,(foramf °:ale) ; *' ?

£>, semicircular canals ; * represents

the bulging part (ampulla) of each
canal ; E, F, G, cochlea ; //, round
window (foramen rotundum).

window, passing the auditory
impulse inwards to the internal
ear.

Every time the stirrup bone is pushed in and drawn out
of the oval window the watery fluid (the perilymph) in the
inner ear is set in motion more or less violently, accord-
ing to the intensity of the sound. The membranous

270 Life and Health

labyrinth occupies the central portion of the vestibule and
the passages leading from it. When, therefore, the peri-
lymph is shaken it communicates the impulse to the fluid
(endolymph) contained in the inner membranous sac.

The endolymph is now driven against the sides of the
membranous sac and so strikes the ends of the nerves of
hearing, which transmit the auditory impulses to the seat
of sensation in the brain.

It is in the seat .of sensation in the brain that the vari-
ous auditory impulses received from different parts of the
inner ear are interpreted as sounds. It is the extent of
the vibrations that determines the loud ness of the sound ;
the rapidity of them that determines the pitch.

NOTE. — The otoliths and the semicircular canals probably have
nothing to do with the sense of hearing. They enable us to feel the
position of the head, and thus help us to preserve our equilibrium.

•' Experiment 122. Hold a ticking watch between the teeth, or touch
the upper incisors with a vibrating tuning fork ; close both ears and
observe that the ticking or vibration is heard louder. Unstop one
ear and observe that the ticking or vibration is heard loudest in the
stopped ear.

Experiment 123. Hold a vibrating tuning fork on the incisor teeth
until it can no longer be heard. Close one or both ears, and it will
be heard again.

Experiment 124. Listen to a ticking watch or a tuning fork kept
vibrating electrically. Close the mouth and nostrils and take either
a deep inspiration or deep expiration, so as to alter the tension of the
air in the tympanun ; in both cases the sound is diminished.

- Experiment 125. With a blindfolded person test his sense of the
direction of sound, e.g., by clicking two coins together. It is very
imperfect. Let a person press both auricles against the side of the
head and hold both hands vertically in front of each meatus. If a
person makes a sound in front, the observed person will refer it to a
position behind him.

The Special Senses

271

VESTIBULE WITH OPENINGS
JOF SEMICIRCULAR CANALS

8CALA VESTIBULI

NCUS

_/_MALLEU8
—STAPES

426. Practical Hints on the Care of the Ear. The ears
are often neglected when skilled treatment is urgently
needed, and they are often ignorantly and carelessly tam-
pered with when they should be left alone.

Never insert into the ear canal the corners of towels,
ear spoons, the ends of toothpicks, hairpins, or any other
pointed instruments. It is a needless and dangerous prac-
tice, usually causing, in time, some form of inflammation.

Again, there is always risk that the elbow may be jogged
and the instrument pushed through the drumhead. There
is, of course, a
natural impulse to
relieve itching of
the ear when it
occurs. This
should be done
with the tips of
the fingers or not
at all.

Very cold water
should never be
used to bathe the
ears and nostrils. Bathe moderately and gently in lukewarm
water, using a wash rag in preference to a sponge ; dry
gently and thoroughly. Do not go to sleep with the head
on a window sill or in any position in which the ears are
exposed to draughts of cold or damp air.
. Never shout suddenly in a person's ear. The ear is
not prepared for the shock, and deafness has occasionally
resulted. Insects may gain entrance to the ears and
occasion annoyance, pain, and fright, perhaps leading to
vomiting, even to convulsions, with nervous children.
A lighted lamp held at the entrance of the ear will often

EXT. AUD. MEATUS.
-— MEMBRANA TYMPANI

EUSTACHIAN TUBE

FIG. 145. Diagram of the Middle and Internal Ear.

272 Life and Health

induce the offending insect to crawl out towards the
light. A few drops of warm water, sweet oil, or molas-
ses dropped into the ear will help remove the intruder.

427. Additional Suggestions on the Health of the Ears.
No effort should be made to remove the earwax unless it
unduly accumulates. The skin of the canal grows outward,
and the extra wax and dust' will be naturally carried out
if let alone. Never employ any of the many articles or
"drops" advertised to cure deafness. Neuralgic pain in
the auditory canal, usually classed as earache, may be due
to decayed or improperly filled teeth.

The practice of snuffing up cold water into the nostrils
is occasionally followed by an acute inflammation of the
middle ear, especially if some of the water finds its way
through the Eustachian tube into this part of the organ of
hearing. The nasal douche, so often advised as a home
remedy for nasal catarrh, should be used only in accordance
with directions from a physician.

Quinine, so generally used in its many preparations for
malaria, causes a peculiar ringing or buzzing in the ears.
This is a warning that it should be taken in smaller doses,
or perhaps stopped for a time. In some cases quinine may
produce temporary deafness.

428. Effect of Alcohol and Tobacco upon the Hearing.
Alcoholic beverages tend to inflame the mucous membrane
of the throat, then the lining of the Eustachian tube, and
finally may injure the delicate apparatus of the internal ear.

The sense of hearing may be injured by the immoderate
use of tobacco. The irritating smoke, filling all the inner
cavity of the mouth and throat, readily finds its way up the
Eustachian tube and irritates the delicate middle ear. Thus
alcohol and tobacco may produce a partial loss of hearing,
accompanied with ringing in the ears.

The Special Senses 273

ADDITIONAL EXPERIMENTS

Experiment 126. Use a small pair of wooden compasses, or an
ordinary pair of dividers with their points guarded by a small piece of
cork. Apply the points of the compasses lightly and simultaneously
to different parts of the body and ascertain at what distance apart the
points are felt as two. The following is the order of sensibility : tip
of tongue, tip of the middle finger, palm, forehead, and back of hand.

Experiment 127. By means of a spray producer spray the back
of the hand with ether and observe how the sensibility is deadened.

Experiment 128. Generally speaking, the sensation of touch is
referred to the cutaneous surfaces. In certain cases, however, it is
referred even beyond this. Holding firmly in one hand a cane or a
pencil, touch an object therewith ; the sensation is referred to the
extremity of the cane or pencil. If, however, the cane or pencil be
held loosely in one's hand, one experiences two sensations : one cor-
responding to the object touched, and the other due to the contact
of the rod with the skin.

Experiment 129. Wipe the tongue dry and lay on its tip a crystal
of sugar. It is not tasted until it is dissolved.

Apply a crystal of sugar to the tip, and another to the back of the
tongue. The sweet taste is more pronounced at the tip.

Experiment 130. Prepare a strong solution of sulphate of qui-
nine with the aid of a little sulphuric acid to dissolve it (bitter), a
5 per-cent solution of sugar (sweet), a 10 per:cent solution of com-
mon salt (saline), and a I per-cent solution of acetic acid (acid).
Repeat the process in Experiment 129 with sulphate of quinine in
solution. It is scarcely tasted at the tip, but is tasted immediately
on the back part of the tongue.

Test in the same way the places in which the salines and acids are
tasted most acutely.

Experiment 131. To illustrate the mtiscular sense. Take two
equal iron or lead weights ; heat one and leave the other cold. The
cold weight will feel the heavier.

Experiment 132. Place a thin disk of cold\v&&, the size of a silver
dollar, on the forehead of a person whose eyes are closed ; remove the
disk, and on the same spot place two warm disks of equal size. The

274

Life and Health

person will judge the two warm disks to be about the same weight,
or lighter, than the single cold disk.

Experiment 133. To illustrate the influence of excitation of one
sense organ upon the other sense organs. On listening to the ticking
of a watch, the ticking sounds feebler or louder on looking at a light
through glasses of different colors.

If the finger be placed in cold or warm water the temperature
appears to rise when a red glass is held in front of the eyes.

Experiment 134. To show the movements of the iris. Look
through a pin hole in a card at a uniform white surface, as the
white shade of an ordinary reading lamp. With the right eye
look through the pin hole, the left eye being closed. Note the size
of the (slightly dull) circular visual field. Open the left eye, the field
becomes brighter and smaller (contraction of pupil) ; close the left
eye, after an appreciable time, the field (now slightly dull) is seen
gradually to expand. One can thus see and observe the rate of
movements of his own iris.

- Experiment 135. To show the blind spot. The left eye being
shut, let the right eye be fixed on the cross as in Fig. 146. When

FIG. 146.

the book is held at arm's length both cross and round spot will be
visible ; but if the book be brought to about eight inches from the eye,
the gaze being kept steadily upon the cross, the round spot will at
first disappear, but as the book is brought still nearer both cross and
round spot will again be seen.

Experiment 136. To illustrate the
duration of retinal impressions. On
a circular white disk, about halfway
between the center and circumference,
fix a small, black, oblong disk, and rap-
idly rotate it by means of a rotating

™ ^. °P"CD'S*S- wheel. There appears a ring of gray
(The disk A, when rotated rap- , . , L Al .

idly, gives an even gray tint £ on the black> showmg that the imPrCS'
in £\ sion on the retina lasts a certain time.

The Special Senses

275

Experiment 137. Mark off a round piece of cardboard into black
and white sectors modeled after the disk in A (Fig. 147). Attach
it so as to rotate it rapidly, as on a sewing machine. An even gray
tint will be produced as in B.

Experiment 138. To illustrate imperfect visual judgments.
Make three round black dots, A, B, C, of the same size, in the same

line, and let A and C be equidistant from B. Between A and B
make several more dots of the same size. A and B will then appear
to be farther apart than B and C.

Experiment 139. Make on a white card two squares of equal size.
Across the one draw horizontal lines at equal distances, and in the
other make similar vertical lines. Hold them at some distance.
The one with horizontal lines appears higher than it really is, while
the one with vertical lines appears broader, i.e., both appear oblong.

Experiment 140. Look at the row of letters (S) and figures (8).
SSSSSSSS 88888888

To some the upper halves of the letters and figures may appear to be

of the same size as the lower halves,

to others the lower halves may appear

larger. Hold the figure upside down

and observe that there is a considerable

difference between the two, the lower

halves being considerably larger.

Experiment 141. The length of a
line appears to vary according to the
angle and direction of certain other
lines in relation to it (Fig. 148). The
length of the two vertical lines is

the same, yet B appears much longer FIG. I4g. TO show False
than A. Estimate of Size.

CHAPTER XII
THE THROAT AND THE VOICE

429. The Throat. The throat is a double highway, as it
were, through which the air we breathe passes to the larynx
on its way to the lungs, and through which the food we
swallow reaches the oesophagus on its passage to the stomach.
It is, therefore, a very important region of the body, being
concerned in the great acts of respiration and digestion.

The throat is enclosed and protected by various muscles
and bony structures, along which run the great blood vessels
that supply the head and the great nerve trunks that pass
from the brain to the parts below. The throat is lined
with mucous membrane covered with ciliated epithelium,
which secretes a lubricating fluid (mucus) which keeps the
parts moist and pliable.

• We have already described the food passages (Chapter VI)
and the air passages (Chapter VIII).

430. What may be seen in the Open Mouth. If we look
into the wide-open mouth of some friend and depress the
tongue, we can readily see the back wall of the pharynx.
This is common to the two main avenues leading to the
lungs and the stomach. Above, we notice the air passages
which lead to the posterior cavities of the nose.

The hard palate, the soft palate, the uvula, and the tonsils
have already been described (Figs. 45 and 51).

On looking directly beyond these organs we see the
beginning of the downward passage, — the pharynx. If

276

The Throat and the Voice

277

now the tongue be forcibly drawn forward, a curved ridge
may be seen behind it. This is the epiglottis, which, as
we have already learned, shuts down, like the lid of a
box, on the top of the larynx (sees. 156 and 246).

431. The Larynx. The larynx, the essential organ of
voice, forms the box-like top of the

windpipe. It is built of variously
shaped cartilages, connected by
ligaments. It is clothed on the
outside with muscles ; on the inside
it is lined with mucous membrane,
continuous with that of the other
air passages.

432. The Thyroid Cartilage. The
larynx has for a framework two
cartilages, the thyroid and the cricoid,
one above the other.

The larger of these, called the

thyroid, from a supposed resem-

FIG. 149. View of the Carti-

blance to a shield, Consists of two lages and Ligaments of the
extended wings which join in front Larynx. (Anterior view.)

but are separated by a wide interval A, hyoid bone; B, thyro-hyoid

behind. The united edges in front

project and form the "Adam's

apple," plainly seen and easily felt

on most people, especially on very

lean men.

Above and from the sides rise
two horns which are connected by bands to the hyoid bone,
from which the larynx is suspended (sec. 42 and Fig. 45).

From the underside of the thyroid two horns project
downwards to become jointed to the cricoid. The thyroid
thus rests upon, and is movable on, the cricoid cartilage.

membrane; C, thyroid carti-
lage; D, crico-thyroid mem-
brane ; E, cricoid cartilage,
lateral ligaments seen on each
side; F, upper ring of the
trachea. (" Adam's apple " is
in the V-shaped groove on a
line with B and C.)

278

Life and Health

433, The Cricoid Cartilage. The cricoid cartilage, so
called from its fancied resemblance to a signet ring, is
smaller but thicker and stronger than the thyroid and
forms the lower and back part of the cavity of the larynx.
This cartilage is quite sensitive to pressure from the fingers

and is the cause of the sharp pain
felt when we try to swallow a
large and hard piece of food not
properly chewed.

434. The Arytenoid Cartilages.
On the upper edge of the cricoid
cartilage are perched a pair of
very singular cartilages, pyramidal
in shape, called the arytenoid, which
are of great importance in the pro-
duction of the voice.

These cartilages are capped
with little horn-like projections
and give attachment at their
anterior angles to the true vocal
FIG. 1 50. Diagram of a Sec- cords, and at their posterior angles
tional View of Nasal and tQ the musdes which open and
Throat Passages.
C, nasal cavities; T, tongue; close the glottis, Or Upper Opening

L, lower jaw; M, mouth; u, of the windpipe. When in their

uvula; E epiglottis ; G, larynx; natural position the arytenoid
O, (Esophagus.

cartilages resemble somewhat the
mouth of a pitcher, hence their name.

435. The Vocal Cords. The mucous membrane which
lines the various cartilages of the larynx is thrown into
several folds. Thus, one fold, the free edge of which is
formed of a band of elastic fibers, passes horizontally out-
wards from each side towards the middle line, at the level
of the base of the arytenoid cartilages.

The Throat and the Voice

279

These folds are the true vocal cords, by the movement of
which the voice is produced.

Above them are other folds of mucous membrane called
the false vocal cords, which take no part in the production
of the voice.

The arrangement of the true
vocal cords, projecting as they do
towards the middle line, reduces to
a mere chink the space between
the part 'of the larynx above them
and the part below them. This
constriction of the larynx is called
the glottis.

- 436. The Mechanism of the Voice.
The mechanism of the voice may be
more easily understood by a study
of Fig. 151. We have here the
larynx, viewed from behind, with
all the soft parts in connection
with it. On looking down, the
folds forming the true vocal cords
are seen enclosing a V-shaped
aperture (the glottis), the narrow
part being in front.

The form of this aperture may
be changed by the delicately
coordinate action of the muscles of the larynx. For
instance, the vocal cords may be brought so closely together
that the space becomes a mere slit. Air forced through
the slit will throw the edges of the folds into vibration, and
a sound will be produced (Figs. 153 and 154).

The variations in the form of the opening will determine
the variations in the sound. If the various muscles of the

FIG. 151. View of the Carti-
lages and Ligaments of the
Larynx. (Posterior view.)

A, epiglottis; B, thyroid carti-
lage; C, arytenoid cartilage;

D, ligament connecting lower
cornu of the thyroid with the
back of the cricoid cartilage;

E, cricoid cartilage ; F, upper
ring of the trachea.

280

Life and Health

larynx be relaxed, the opening of the glottis is wider. Thus

the air enters and leaves the larynx during breathing, with-
out throwing the cords into vibration
enough to produce any sound.

In a general way, we may say that
the production of the voice is effected
by an arrangement like that of some
musical instruments, the sounds pro-
d.uced by the vibrations of the vocal
cords being modified by the tubes
above and below.

All musical sounds are due to move-
ments or vibrations occurring with a
certain regularity, and they differ in
loudness, pitch, and quality.

Loudness of the sound depends
upon the extent of the vibrations, and
pitch on the rapidity of the vibrations.
The quality depends upon the admix-
ture of tones produced by vibrations
of varying rates of rapidity, related to
one another.

X437. Factors in the Production of
the Voice. We have just learned that
the pitch of sound depends on the
rapidity of the vibrations. This
depends upon the length of the cords
and .their tightness, for the shorter
and tighter a string is, the higher is
the note which its vibration produces.
The vocal cords of women are about

one-third shorter than those of men, hence the higher

pitch of the notes they produce.

FIG. 152. Longitudinal
Section of the Larynx.
(Showing the vocal
cords.)

A, epiglottis ; B, section of
hyoid bone; C, superior
vocal cord; D, ventricle
of the larynx ; E, inferior
vocal cord ; P, section of
the thyroid cartilage ; //,
section of anterior portion
of the cricoid cartilage;
K, trachea ; L, section of
the posterior portion of
the cricoid cartilage ; M,
arytenoid cartilage ; A^,
section of the arytenoid
muscle.

The Throat and the Voice 281

In children the vocal cords are shorter than those of
adults. The voices of boys " break," or " change," because
of the sudden growth or enlargement of the larynx and
consequent increase in length of the vocal cords, at from
fourteen to sixteen years of age. Those qualities of the
voice which we speak of as sweet, harsh, and sympathetic
depend to a great extent upon the peculiar structure of
the vocal cords of the individual.

The general shape and structure of the trachea, the
larynx, the throat and mouth, also influence the quality
of voice. Thus the air passages, both below and above
the vibrating cords, act as resonators, or resounding
chambers, and intensify and modify the sounds produced
by the cords. It is this fact that prompts skillful teachers
of music and elocution to urge upon their pupils the
necessity of the mouth being properly opened during
speech, and especially during singing.

Experiment 142. To show the anatomy of the throat. Study
the general construction of the throat by the help of a hand mirror.
Repeat the same on the throat of some friend.

Experiment 143. To show the construction of the vocal organs.
Get a butcher to furnish the windpipes of two sheep or calves.
The vocal organs of these animals differ somewhat from those of the
human body, but the different parts which have been described can
be readily recognized.

One specimen should be cut open lengthwise in the middle line in
front, and the other cut in the same way from behind.

•7 438, Speech. Speech is to be distinguished from voice.
It may exist without voice, as in a whisper.

Speech consists of articulated sounds, that is, interrupted
sounds, the interruptions being produced by the action of
various parts of the mouth, throat, and nose.

282

Life and Health

Voice is common to most animals, but speech is the
peculiar privilege of man.

The organ of speech is perhaps the most delicate and
perfect motor apparatus in the whole body. It has been
calculated that upwards of nine hundred
movements per minute can be made by
the movable organs of speech during
reading, speaking, and singing. It is
said that a hundred different muscles of
the body are called into action in talking.
Each part of this delicate apparatus is
FIG. 153. Diagram- so admirably adjusted to every other that
matic Horizontal all parts of it act in perfect harmony.

Section of Larynx. y 439 production of Articulate Sounds.

(Shows the direction of ,_ . ,

pull of the posterior To secure an easy and proper production
crico-arytenoid mus- of articulate sounds, the mouth, teeth,

cles, which abduct the , . , , A , , , ,

vocal cords. Dotted hPs> tongue, and palate should be in per-
lines show position in feet order. The modifications in articu-
lation which are occasioned by a defect
in the palate or in the uvula, and by the loss of teeth, are
sufficiently familiar.

Many animals have the power of making articulated
sounds ; a few have risen, like man, to the dignity of
sentences, but accomplish this only by imitation of the
human voice. Both vowels and consonants can be dis-
tinguished in the notes of birds.

Persons idiotic from birth are often incapable of produ-
cing any other vocal sounds than inarticulate cries, although
supplied with all the internal means of articulation. Per-
sons born totally deaf are in the same situation, though
from a different cause ; the one being incapable of imitating,
and the other being deprived of the power of hearing the
sounds to be imitated.

The Throat and the Voice

283

( 440, Whispering and Stammering. In whispering, the

larynx takes scarcely any part in the production of the
sounds ; the vocal cords remain apart and comparatively
slack, and the expiratory blast rushes through without
setting them in vibration.

In stammering, spasmodic contraction of the diaphragm
interrupts the effort of expiration. The stammerer has
full control of the mechanism of articulation, but not of
the expiratory blast. His larynx and his lips are at his
command, but not his diaphragm. To conquer this defect
he must train his muscles of respiration to steady action
during speech.

The stutterer, on the other hand, has
full control of the muscles of expiration.
His diaphragm is well drilled, but his lips
and tongue are insubordinate.
/ 441. Hints on the Care of the Throat.
The throat, exposed as it is to unwhole-
some and overheated air, irritating dust FIG. 154. Direction
of the street, factories, and workshops, is

£l_ . ,, , . . J_.

often inflamed, resulting in that common
ailment, sore throat. The parts are red,
swollen, and painful on swallowing, but
rarely require any special treatment.

The action of cold air upon the heated
body, especially during active perspiration, is a very
common cause of throat trouble. For this reason a cold
bath should not be taken while a person is perspiring
freely.

The muscles of the throat are frequently overstrained
by loud talking, screaming, shouting, or by reading aloud
too much. People who strain or misuse the voice often
suffer from what is called " clergyman's sore throat."

of Pul1 of the

Lateral Crico-

ArytenoidS) which
adduct the Vocal
Cords.

284 Life and Health

Persons subject to throat disease should take special care
to wear suitable underclothing, adapted to the changes of
the seasons. Frequent baths are excellent tonics to the
skin and serve indirectly to protect one liable to throat
ailments from changes in the weather. It is not prudent
to muffle the neck in scarfs, furs, and wraps, unless per-
haps during an unusual exposure to cold. Such a dress
for the neck only makes the parts tender and increases
the liability to sore throat.

442. Hints for the Care of the Voice. Every teacher of
elocution or of vocal music should have a practical knowl-
edge of the mechanism of the voice. Good voices are
often injured by an injudicious and incompetent instructor.
Never use the voice when its weakness or failure gives
warning that the general health is impaired. Undue strain
is often put upon the voice even by conversation in steam
or electric cars, and other noisy places. Cease speaking or
singing the moment there is any hoarseness or sore throat.
Always stop before fatigue is felt. Avoid sudden changes
from hot to cold air, even when the voice has not been
used.

The voice should not be exercised just after a full meal,
for a full stomach interferes with the free play of the dia-
phragm. A sip of water taken at convenient intervals, and
held in the mouth for a moment or two, will relieve the
dryness of the throat during the use of the voice.

443. Effect of Alcohol and Tobacco upon the Throat and \
Voice. Alcoholic beverages often injure the throat, and
consequently the voice, by irritating the membrane of the
larynx and the vocal cords. The vocal cords may be thick-
ened, roughened, and enfeebled, and their delicate vibra-
tion may be impaired. The clearness and purity of the
vocal tones may be diminished. Hence vocalists, whose

The Throat and the Voice 285

fortune is the purity and compass of their tones, are carer
f ul not to impair these fine qualities by the habitual use of
strong drink.

Tobacco often produces a disease well known to physi-
cians as "the smoker's sore throat." It may also cause
inflammation of the larynx and thus may entail disorders
of the vocal cords, involving rough voice and harsh tones.
For this reason vocalists should not attempt to use the
voice in a room full of tobacco smoke.

ADDITIONAL EXPERIMENTS

Experiment 144. To illustrate the importance of the resonating
cavity of the nose in articulation. Pinch the nostrils and try to
pronounce slowly the words "Lincoln," "something," or any other
words which require the sound of m, In, or ng.

Experiment 145. To illustrate the passage of air through the
glottis. Take two strips of India rubber and stretch them over the
open end of a boy's " bean blower," or any kind of a tube. Tie them
tightly with thread, so that a chink will be left between
them, as shown in Fig. 155.

Force the air through such a tube by blowing hard,
and if the strips are not too far apart, a sound will be
produced. The sound will vary in character, just as the
bands are made tight or loose.

NOTE. — The limitations of a text-book on physiology
for schools do not permit so full a description of the voice
as the subject deserves. For additional details, the stu- FIG. 155.
dent is referred to Cohen's The Throat and the Voice, a
volume in the American Health Primer Series, and Browne and
Behnke's Voice, Song and Speech.

CHAPTER XIII
THE PRESERVATION OF HEALTH

444. The Teachings of Modern Hygiene. Modern hygiene
not only formulates rules for the preservation of health,
but it goes much farther and treats of the prevention of disease.
It warns us of the unseen and invisible foes which assail
our health at every moment and teaches us the best meth-
ods to check the prevalence of disease. Even if we obey
every law of hygiene, we cannot, of course, wholly avoid
these invisible enemies, but it is none the less true that
there is a power in every healthy human body that may
successfully battle the germs of disease. This power is
best conserved and developed by living up to the best
hygienic standards.

BACTERIA

445. Nature and Propagation of Bacteria. The words
bacteria, bacilli, germs, micro-organisms, and microbes are terms
commonly applied to certain low forms of plant life of
microscopic size.

If some finely chopped hay be covered with water and
set in a warm place for a few days, and a few drops of the
liquid are examined under a high power of the microscope,
the water is found to be swarming with various forms of
living organisms, chiefly bacteria.

These microscopic plants belong to the great fungus
division. They consist of many varieties, which may

286

The Preservation of Health

287

be roughly divided into groups, according as they are
spherical, rod-like, or spiral in shape. The term bacillus is
usually restricted to rod-shaped bacteria.

Bacteria are propagated in a very simple manner. Usu-
ally the parent cell divides into two ; these two into two
others, and so on. Under certain conditions, however,
bacteria reproduce
themselves by
spores which are
formed in the inte-
rior of cells and
then passed out.
These spores are
much more tena-
cious of life and
therefore are much

FIG. 156. Various Forms of Bacteria. (Drawn
from photographs.)

A, spheroidal bacteria (called cocci} in pairs ; J5, same
kind of bacteria in chains ; C, bacteria found in pus

(grouped in masses like a bunch of grapes). (Bacteria
in A, B, and C magnified about 1000 diameters.)
Z>, bacteria found in pus (tendency to grow in the
form of chains). (Magnified about 500 diameters.)

harder to destroy
than the fully de-
veloped cells. The
rapidity with which bacteria multiply under favorable con-
ditions makes them, in some cases, dangerous enemies
to plant and animal life.

446. General Action of Bacteria. Bacteria have the
power of bringing about decomposition of various kinds.
Thus, as we have learned in a previous chapter, a highly
organized fungus, like the yeast plant, growing in the
presence of sugar, has the power of breaking down this
complex body into simpler ones, viz., alcohol and carbon
dioxide (see Experiment 29).

In the same way various forms of bacteria have the
power of breaking down complex bodies, the products
depending upon the substance, the kind of bacteria, and
the conditions under which they act. Thus, the bacteria

288 Life and Health

lac t is act upon the milk sugar present in milk and con-
vert it into lactic acid, thus bringing about the souring
of milk.

447, The Place of Bacteria in the Economy of Nature.
The myriads of bacteria, with their marvelous rapidity of
propagation, would devastate the earth were it not for the
winds, rains, melting snow and ice which scatter them far
and wide and destroy them.

Like countless other species of living organisms, bacteria
are subject to the relentless law which allows only the fittest
to survive. The bacteria of higher and more complex types
devour those of a lower type. Myriads perish in the diges-
tive tract of man and other animals. The excreta of some
species of bacteria act as poison to destroy other species.

448. Disease-Producing Bacteria. Now, while many spe-
cies of bacteria are harmless, some may be the cause of
sickness and death when they gain admittance to the body

under certain con-
ditions. These
disease-producing, or
pathogenic, bacteria,
when established in

FIG. 157 .^Two Forms of Pathogenic Bacteria. the tlsSUeS °f the

(Drawn from phbtographs.) b°dy> ma7 P™duce

A, spiral form of bacteria found in cholera. (Magni- a particular disease.

fied about 1000 diameters.) B, rod-shaped bacteria It has been proved

(called bacilli) from a culture obtained in anthrax, -\ -, -,-, -, •, .

or malignant pustule, of the face. Diseased hides beyond all ^ doilbt

carry this micro-organism and thus may occasion that Certain dis-

disease among those who handle hides and wool. ' e<; arp nrOfli]red

(Magnified about 1000 diameters.)

through the agency

of bacteria. In yellow fever, diphtheria, typhoid fever, and
consumption the causal relation of a particular kind of bac-
teria to each disease has been definitely established.

The Preservation of Health

289

449. Disease-Producing Bacteria in the Soil. Surface
soils, especially those rich in organic matter, abound in
many kinds of bacteria. There seems to be an intimate
relation between the soil and important bacterial diseases.

The terrible disease called tetanus, or " lockjaw," is known
to be due to a micro-organism common in the soil of certain
localities.

Typhoid bacilli were kept alive for 456 days by one
experimenter in soil which had been polluted with organic
matter. Farm soils have been contaminated with the
bacilli of anthrax, or malignant pustule (Fig. 157), and have
retained the infectious virus for several months.

In brief, the disease-producing bacteria found in the
surface soils can and do retain their vitality, and some-
times even their virulence, for long periods of time.

450. Disease - Pro-
ducing Bacteria in
Foods. Good food as
well as bad frequently
contains large num-
bers of bacteria. It
is fortunate, however,
that harmful micro-
organisms are usually
killed by cooking.
Not all the persons
eating infected food
suffer equally, and
oftentimes some
escape altogether.

Bacteria have a
special fondness for milk. In a hundred different ways, milk
runs the risk of being polluted, — as from the animal, the

FIG. 1 58. Bacilli of Typhoid Fever.
(Magnified 1000 diameters.)

290 Life and Health

milker, unclean methods of milking, the addition of typhoid-
infected water, the use of unclean utensils and milk cans.

Typhoid fever and other infectious diseases have been
traced to eating raw oysters that were fattened in salt
water contaminated with the sewage. Disease-producing
bacteria, as the typhoid bacillus, have been found in ice,
and even in ice cream. Milk and meat from tuberculous
animals have not unfrequently produced disease. Persons
are occasionally poisoned from eating canned meats which
have been contaminated with bacteria or their products.

Other foods and beverages are often contaminated with
injurious bacteria, generally due to uncleanly manufacture
or unprotected storage.

451. Some Common Diseases caused by Bacteria. The
malign results brought about by certain bacteria vary greatly
in kind and severity. Thus the bacteria of Asiatic cholera
and diphtheria may destroy life in a few hours, while those
of consumption may take years to produce a fatal result.
Again, bacteria may attack some particular organ, or group
of organs, and produce mostly local symptoms. Thus, in a
boil there is painful swelling due to the local effect of bacteria,
usually accompanied with slight general disturbance.

The epidemic disease known as influenza, or la grippe,
or the "grip," is due to a specific germ. It attacks the
mucous membranes more commonly than any other parts
of the body, although hardly any organ has escaped.

452. How Bacteria gain Access to the Bodily Tissues.
There are several possible ways in which germs of disease
may gain access to the tissues. First, by contact between
diseased and healthy persons ; in brief, by contagion.
Thus, ringworm, often called barber's itch, is a familiar
example of bacteria " caught " from the germs on a razor
or a soiled towel.

The Preservation of Health

291

As stated before, bacteria may enter the body with the
food and water. We have already shown how the air may
become infected with the germs of disease from the dust
of dried sputa (page 177).

Finally, bacteria may gain access to the body by
inoculation, or by inserting the virus through a broken
surface of the skin. This may result from using soiled
instruments, from gunshot injuries, broken glass, rusty
nails, and from many other causes.

453. How the Body defends itself against Bacteria.
Germs of disease constantly assail the bodily tissues.
There is a continual
warfare between bac-
teria and the living
cells. The plasma of
the blood acts in some
unknown manner to
help kill the disease-
producing germs.

The white blood
corpuscles wage an
unceasing warfare
against bacteria and
the toxins. While
this warfare is going
on and disease shows
itself, a poison of

FIG. 1 59. Bacilli of Diphtheria.
(Magnified 1000 diameters.)

another type, called for convenience antitoxin, is formed in
the serum of the blood, which may antagonize the toxins
and destroy their poisonous action.

454. Antitoxin Treatment of Disease. Within the past
few years remarkable progress has been made by tireless
scientific workers in their efforts to modify the action of

292 Life and Health

disease-producing bacteria. For instance, the toxins of
diphtheria germs are injected into the blood of a horse.
In due time the antitoxin of the disease is removed from
the serum of the infected blood, and after proper prepara-
tion is injected into the blood of a person exposed to or
suffering from diphtheria. The effect is to modify decid-
edly the action of the poisonous germs of this dread
disease.

455. How the Bacteria may behave within the Body.
After gaining access to the body the bacteria may begin
a twofold sort of action. Thus, the bacteria themselves
may act, and their products, called toxins, may also play
their part. For example, the term "infection" is applied
to those conditions in which there is a multiplication of
bacteria after entering the body. The word "intoxication "
is often used to indicate a condition of poisoning brought
about by their products, or toxins. Until these toxins
begin to act there may be no symptoms of disease.
Thus, one may drink typhoid-polluted water. The bacilli
multiply for two weeks (the period of incubation) without
any sign, but at the end of about fourteen days the typhoid
toxins assert themselves, and symptoms of the disease
appear.

456. What may happen when Bacteria gain Access to a
Wound. Nowhere do the bacteria make their power more
distinctly felt than in the changes which they may produce
when they gain access to a wound. They now find just
the conditions upon which they thrive, as heat, moisture,
and an abundance of food in the form of broken-down
organic matter. Now comes the tug of war between the
germs of disease and the cells of the body, especially the
white blood corpuscles. Sometimes the cells of the body
conquer, and sometimes they are destroyed. More blood

The Preservation of Health 293

is sent to the affected part, resulting in redness and heat
about the wound. The bodily cells multiply rapidly and
form a barrier to retard the action of the bacteria. Usually,
these cells appear upon the surface of the wound and carry
along bacteria with them. The discharge, consisting of
these cells of the body, lymph, and bacteria, is known as
matter, or pus.

In this relentless warfare between the bacteria and living
cells, if the former win, a certain portion of the tissues about
the wound dies ; if the cells are victorious, the tissues heal.

457. Septic Poisoning. Bacteria, after gaining access to
a wound, may produce toxic substances, which may enter
the blood current and prove an additional source of poison.
This is known as septic infection, or commonly septicczmia.
The slight fever resulting from a boil or abscess may be
due to this cause.

Sometimes these bacteria may get fastened into a clot
of blood which softens, and portions of it may be carried
to distant parts of the body by the blood current and there
produce abscesses. This poisoning is known as py<zmia.

458. Alcoholic Fermentation and Bacteria. Men of all
ages and lands have known that when the sugary juice of
any fruit is left to itself for a time, at a moderately high
temperature, a change takes place under certain conditions,
and that the result is a liquid which, when drank, produces
a pronounced effect upon the body.

The real cause of this remarkable change in fruit juice
was not known until revealed in recent years by the aid of
the microscope. We know now that this change is due to
alcoholic fermentation, brought about by the action of micro-
scopic fungi (sec. 141).

In other words, alcoholic or vinous fermentation is the
result of the growth and activity of low forms of vegetable

294 Life and Health

life known as organized ferments. These ferments, whether
they are the commonly used brewer's yeast or any other
species of alcoholic ferments, have the power to decompose
or break down a large part of the sugar present in the
liquid into alcohol, which remains as a poison, and carbon
dioxide, which escapes more or less completely.

Thus man has now forced into his service the latest dis-
coveries in science, more especially in bacteriology, that he
may manufacture more scientifically and more economically
alcoholic beverages of all sorts and kinds.

It matters little how, when, or where this process of
alcoholic fermentation is brought about ; the outcome and
the intent are one and the same. The essential thing is to
produce an alcoholic beverage which will have a marked physiological
effect. This effect is poisonous, and is due solely to the
alcoholic constituent, without which man would have little or
no desire for an otherwise harmless liquid.

Experiment 146. The microscopic study of yeast. Draw off by
means of a pipette a drop from the sediment of the " working " mix-
ture in Experiment 29 and place it on a glass slide. Cover with a thin
cover-glass and examine under the high power of the microscope
(300 to 400 diameters). Note the yeast cells and the new cells
budding from the parent cells.

Experiment 147. The examination of pathogenic bacteria by
means of the microscope. Examine with the microscope prepared
slides of culture of the bacteria that produce diphtheria (Fig. 159),
typhoid fever (Fig. 158), consumption (Fig. 92), and such other
slides of pathogenic bacteria as can be readily obtained from
dealers in microscopical supplies.

The Preservation of Health 295

THE PREVENTION AND RESTRICTION OF DISEASE

459. Means to avert Danger of Disease. From the
preceding pages we have learned many of the simplest
principles which underlie the maintenance of good health.
Wholesome food, pure air, proper clothing, cleanliness,
and physical exercise all play their part in maintaining
good health and in preventing disease.

We have now to consider other means used to avert
danger of disease. The whole question strictly concerns
public sanitation, which does not come within the scope of
this book. It is well, however, for every intelligent person
to understand a few of the simplest facts of so important
a subject and one which affects the welfare of every
community.

460. Vaccination, Isolation, and Disinfection, One of
the most familiar means to prevent disease is the use of
vaccination for smallpox. That is, persons who are vacci-
nated are immune, as it is called, from smallpox, or have
it in a milder form.

The diphtheria antitoxin is now quite generally used to
secure immunity from this dangerous disease.

One very common safeguard against the spread of con-
tagious diseases is isolation. The patients, and often the
family, are isolated from other people ; a rigid system of
nursing is instituted, a placard is placed upon the house,
the premises are watched, and other familiar means of isola-
tion are employed.

Disinfection is universally recognized as a most efficient
and practical means to prevent the spread of disease.

461. A Few Words explained. Some substances kill
bacteria and are known as germicides; other substances
prevent the development of bacteria and resulting septic

296 Life and Health

action, and these are called antiseptics. The word "disin-
fectant " is used with more or less confusion to cover both
these words.

Disinfection is strictly the destruction of the germs of
disease by means of heat, chemical agents, fumigation,
or fresh air. An antiseptic, when used in a very strong
dose or for a long time may act as a germicide, while a
germicide in too weak solution to act as such may serve
only as an antiseptic.

A deodorant is a substance that removes or conceals offen-
sive odors. Deodorizers are not necessarily disinfectants.

462. Air and Water as Disinfectants. Nature has pro-
vided for our protection two most efficient means of dis-
infection, — pure air and pure water. The air of crowded
rooms contains large quantities of bacteria, whereas in
pure air there are comparatively few, especially after rain,
which carries them to the earth.

In water tainted with organic matter putrefactive bac-
teria will flourish, whereas pure water is fatal to their
existence. Surface water, because it comes from that
part of the soil where bacteria are most active, and where
there is most organic matter, generally contains great
quantities of these organisms.

463. The more Common Disinfectants. Disinfection
must be secured by other means than fresh air and clean-
liness. The destruction of infected material by fire is, of
course, a sure but costly means of disinfection. Heat in
various forms, as dry heat, steam, and boiling water, is a
valuable disinfectant and does not injure most fabrics.
These agents are generally used in combination with vari-
ous chemical disinfectants.

Certain chemical agents that are capable of destroying
micro-organisms have come, of late years, into general use.

The Preservation of Health 297

A compound of mercury, called corrosive sublimate, is a
most efficacious and powerful germicide, but is exceedingly
poisonous and can be bought only under restrictions.

Carbolic acid, chloride of lime, permanganate of potash,
sulphur, formaldehyde (formalin), and various preparations
made from zinc, iron, and petroleum are the disinfectants
which are most widely used at the present time.

There are also numerous varieties of commercial disinfect-
ants now in popular use which the manufacturers claim to
be efficient germicides.

The Prevention and Restriction of Dangerous Communicable Diseases.

The following directions for the prevention and restriction of danger-
ous communicable diseases are issued by the Michigan Board of
Health for the use of teachers of that state in giving instructions to
the children in the schools.

Consumption is now known to be a communicable disease. It is
spread by the dust of dried sputa, and also by milk and meat of
tuberculous animals. The most important measure for the restric-
tion of consumption is the disinfection or destruction of all sputa
of every consumptive person.

It is best that all persons who have a cough should carry small
pieces of cloth (each just large enough properly to receive one
sputum) and paraffined paper envelopes or wrappers in which the
cloth, as soon as once used, may be put and securely enclosed, and,
with its envelope, burned on the first opportunity. These pieces of
cloth must not be carried loose in the pocket and allowed to dry after
being used.

Pneumonia is spread by a germ which is in the sputum of those
who have the disease. Care should always be taken to destroy or
disinfect all sputa of those who have pneumonia.

Influenza, la grippe, or plain "grip," is now believed to be spread
by a germ which finds its way from infected handkerchiefs and other
articles and places into the nose, throat, and air passages of persons
susceptible to this disease.

298 Life and Health

Diphtheria is spread by the sputa, saliva, and whatever comes from
the throat and mouth of the patient, and by the dust which results
from the drying of such substances. The germs of diphtheria some-
times remain in the throat weeks after apparently complete recovery.
For its restriction and prevention, isolation and disinfection are the
important measures — isolation of every infected person and thing,
and complete disinfection.

Typhoid fever is not so often contracted directly from the sick
person, but usually from the discharges from the bowels and bladder
of the patient. These discharges should always be disinfected.
Undisinfected discharges, if dried and formed into dust, may spread
the disease through the air. The chief source of danger, however, is
believed to be drinking water contaminated by sewage or leachings
from outbuildings. The germs permeate the entire body of an infected
person, and sometimes are found some time after apparent recovery.
The germs of typhoid fever are not always killed by freezing, but are
killed by boiling. All suspected water should be boiled.

Scarlet fever has not yet been identified by its special germ,
but that there is a germ seems to be proved by the well-known com-
municability of the disease from person to person. It is spread by
the discharges from the nose, mouth, and throat, and probably also
by the minute scales which are thrown off from the surfaces of the
body. Isolation and disinfection are the measures by which this
disease is restricted.

THE CARE OF THE SICK ROOM

464. Ventilation of the Sick Room. Proper ventilation is
very essential to the sick room. One of the windows may
be let down an inch or more at the top, a screen being
arranged to avoid any draught on the patient. Remove
all odors by ventilation and not by spraying perfumery,
or burning pastils, which merely conceal offensive odors
without purifying the air.

Avoid ventilation by means of doors, for the stale 'air of
the house, kitchen smells, and noises made by the occupants

The Preservation of Health 299

of the house are apt to reach the sick room. The entire air
of the room should be changed at least two or three times
a day, and in addition a constant supply of fresh air should
be introduced in small quantities. During cold weather and
in certain diseases, the patient may be covered entirely with
blankets and the windows opened wide for a few minutes.

465, Location and Arrangement of the Sick Room. The
sick room, if possible, should be on the quiet and sunny
side of the house. Pure fresh air, sunshine, and freedom
from noise and offensive odors are almost indispensable.
A fireplace, as a means of ventilation, is invaluable. The
bed should be so placed that the air may get to it on all
sides and the nurse move easily around it. Screens should
be used to exclude superfluous light and draughts.

Remove all useless ornaments and articles likely to
collect dust, as unnecessary pieces of furniture and heavy
draperies. A clean floor, with a few rugs to deaden the
sounds of footsteps, is much better than a woolen carpet.
Rocking-chairs should be banished from the sick room, as
they are almost sure to disturb the sick.

A daily supply of fresh flowers tends to brighten the
room. The medicines may be close at hand, but all poisonous
drugs should be kept carefully by themselves and ordinarily
under lock and key. A small table should be placed at the
bedside, and on it the bell, food tray, flowers, and other
small things which promote the comfort of the patient.

466. Hints for the Sick Room. Do not worry the sick
with unnecessary questions, idle talk, or silly gossip. It
is cruel to whisper in the sick room, for patients are always
annoyed by it. They are usually suspicious that something
is wrong and generally imagine that their condition has
changed for the worse. Always strive to look cheerful
and pleasant before the patient. Whatever may happen,

300 Life and Health

do not appear to be annoyed, discouraged, or despondent.
Do your best to keep up the courage of sick persons under
all circumstances. In all things keep in constant mind the
comfort and ease of the patient.

Symptoms of the disease should never be discussed
before the patient, especially if he is thought to be asleep.
He may be only dozing, and any such talk would then be
gross cruelty. Loud talking must, of course, be avoided.
The directions of the physician must be rigidly carried out
in regard to visitors in the sick room. This is always a
matter of importance, for an hour or even a night of needed
sleep and rest may be lost from the untimely call of some
thoughtless visitor.

467. Additional Hints in taking Care of the Sick.
Keep, so far as possible, the various bottles of medicine,
spoons, glasses, and so on, in an adjoining room, rather
than make a formidable array of them on a bureau or
table near the sick bed. A few simple things, as an
orange, a tiny bouquet, one or two playthings, or even a
pretty book, may well take their place.

Sick people take great comfort in fresh linen and fresh
pillows. Two sets should be used, letting one be aired
while the other is in use. In making changes the fresh
linen should be thoroughly aired and warmed and everything
in readiness before the patient is disturbed.

Feather beds are always objectionable in the sick room
for many and obvious reasons. The proper making of a
sick bed, with the forethought and skill demanded in cer-
tain diseases, is of great importance and an art learned
only after long experience. The same principle obtains in
all that concerns the lifting and the moving of the sick.

468. Helps for the Sick Room. Do not deceive sick
people. Tell what is proper or safe to be told, promptly

The Preservation of Health 30 1

and plainly. If a physician is employed, carry out his
orders to the very letter as long as he visits you. Make
on a slip of paper a note of his directions. Make a brief
record of exactly what to do, the precise time of giving
medicines, etc. This should always be done in serious
cases, and by night watchers ; then there is no guess-
work. You have the record before you for easy reference.
All such things are valuable helps to the doctor.

Noises that are liable to disturb the patient, in other
parts of the house than the sick room, should be avoided.
Sounds of a startling character, especially those not easily
explained, as the rattling or slamming of distant blinds
and doors, are always irritating to the sick.

469. Hints on nursing Infectious and Contagious Diseases.
Strip the room of superfluous rugs, carpets, furniture,
etc. Isolate two rooms, if possible, and have these, if
convenient, at the top of the house. Tack sheets, wet
in some proper disinfectant, to the outer frame of the
sick-room door. Boil these sheets every third day. In
case of diseases to which the young are very susceptible,
send the children who have not yet been attacked, if
possible, to houses where there are no children.

The most scrupulous care should be taken in regard to
cleanliness. Old pieces of linen, cheese cloth, and paper
napkins should be used wherever convenient or necessary
and then at once burned. All soiled clothing that cannot
well be burned should be put to soak at once in disinfect-
ants and afterward boiled apart from the family wash.
Dishes and all utensils should be kept scrupulously clean
by frequent boiling. For the bed and person old and worn
articles of clothing that can be destroyed should be used
so far as possible.

CHAPTER XIV
FIRST AID TO THE INJURED

470. Prompt Aid in Common Accidents and Emergencies.

What we have studied in the preceding chapters will
become tenfold more interesting, instructive, and valuable
to us, if we are able to supplement such study with its
practical application to the treatment of the more common
and less serious accidents and emergencies.

While no book can teach one to have presence of mind,
a cool head, or to restrain a more or less excitable tempera-
ment in the midst of sudden danger, yet assuredly with
proper knowledge for a foundation a certain self-confidence
may be acquired which will do much to prevent hasty action
and to maintain a certain amount of self-control.

471. Hints as to what to do first. Retain so far as pos-
sible your presence of mind ; or, in other words, keep cool.
Act promptly and quietly, but not with haste. Whatever
you do in the presence of danger, do in earnest ; and never
act in a half-hearted manner. Be sure and send for a doctor at
once if the emergency calls for skilled service. All that is expected
of you is to tide over matters until the doctor comes.

Make the sufferer comfortable by giving him an abun-
dance of fresh air and placing him in a restful position.
Loosen all tight articles of clothing, as belts, collars, cor-
sets, and elastics.

472. Contusion and Bruises. An injury to the soft tis-
sues, caused by a blow from some blunt instrument or by a

302

First Aid to the Injured

303

fall, is a contusion, or bruise. A black eye, a knee injured
by a fall from a bicycle, and a finger hurt by a base-
ball are familiar examples of injuries which ordinarily
require very simple treatment.

Wring out old towels or pieces of flannel in hot water
and apply to the parts, changing as they become cool.
For cold applications, use cloths wet with water diluted
with vinegar, or witch-hazel.

When wounds are made with ragged edges, such as those
made by broken glass and splinters, more skill is called for.
Remove every bit of foreign sub-
stance. If the skin about the
wound seems to need washing it
should be done with one of the
many antiseptic solutions ; bring
the torn edges together, and hold
them in place with strips of
plaster.

Wounds made by toy pistols,
percussion caps, and rusty nails
and tools, if neglected, often lead
to serious results from blood
poisoning. Keep such wounds FIG. 1 60. Showing how Digital
clean by washing or syringing Compression should be ap-

, , / • ./, plied to the Brachial Artery.

them twice a day with anti-
septics, which kill the bacteria or prevent their growth.

473. Injuries to the Blood Vessels. It is very important
to know the difference between the bleeding from an artery
and that from a vein.

If an artery bleeds, the blood leaps in spurts and is of a
bright scarlet color.

If a vein bleeds, the blood oozes in a steady stream and
is of a somewhat darker color.

304

Life and Health

Bleeding from an artery is a dangerous matter in pro-
portion to the size of the vessel, and may speedily cause
the loss of life itself. When an artery is bleeding always
remember to make deep pressure between the wound and the
heart. In all such cases send for the doctor.

Do not be afraid to act at once. A resolute grip in the
right place with firm fingers will do well enough, until a
twisted handkerchief, stout cord, shoestring, suspender, or
an improvised tourniquet 1 is ready
to take its place. If the flow of
blood does not stop, change the pres-
sure until the right spot is found.

474. Where and how to apply Pres-
sure. The principal places in which
to apply pressure when arteries are
injured and bleeding should always
be kept in mind.

If in the finger, grasp it with the
thumb and forefinger and pinch it

1 A tourniquet is a bandage, handkerchief,
or strap of webbing into the middle of which
a stone, a potato, a small block of wood, or
any hard, smooth body is tied. The band is
tied loosely about the limb, the hard body is
held over the artery to be constricted, and
a stick is inserted beneath the band on the
opposite side of the limb and used to twist the band in such a way that
the limb is tightly constricted thereby, and the hard body thus made to
compress the artery.

The entire circumference of the limb may be constricted by any sort of
elastic band or rubber tube, or any other strong elastic material passed
around the limb several times on a stretch, drawn tight and tied in a knot.
In this way bleeding may be stopped at once from the largest arteries.
The longer and softer the tube the better. It requires no skill and but
little knowledge of anatomy to apply it efficiently. — ALEXANDER B.
JOHNSON, Surgeon to Roosevelt Hospital, New York City.

FIG. 161. Dotted Line
showing the Course of
the Brachial Artery.

First Aid to the Injured 305

firmly on each side; if in the hand, press on the bleeding
spot, or press with the thumb just above and in front of
the wrist.

For injuries below the elbow, grasp the upper part of the
arm with the hands and squeeze hard. The main artery
runs in the middle line of the bend of the elbow. Tie the
knotted cord here and bend the forearm so as to press
hard against the knot.

For the upper arm, press with the fingers against the
bone on the inner side and just on the edge of the bulging
part of the biceps muscle. Take a stout stick of wood,
about a foot long, and twist the cord hard with it, bringing
the knot firmly over the artery.

For the foot or leg, pressure as before, in the hollow
behind the knee, just above the calf of the leg. Bend the
thigh towards the abdomen and bring the leg up against
the thigh, with the knot in the bend of the knee.

Experiment 148." How to tie a square knot. If the student would
render efficient help in accidents and emergencies, to say nothing of
service on many other occasions, he must
learn how to tie a' square or "reef" knot.
This knot is secure and does not slip as does
the "granny" knot. The square knot is the
one used by surgeons in ligating vessels and
securing bandages. Unless one knew the
difference, the insecure " granny " knot might
be substituted. FIG. 162. Showing how

A square knot is tied by holding an end of a Scluare Knot may be
a bandage or cord in each hand, and then tied with a Cord and a

* , . , . 7J , , Handkerchief,

passing the end in the right hand over the

one in the left and tying ; the end now in the left hand is passed
over the one in the right and again tied.

With a handkerchief, shoestring, and cords of various sizes,
practice the square knot until it can be done accurately and
rapidly,

306 Life and Health

475. Bleeding from the Nose. Let the patient sit upright ;
leaning forward with the head low only increases the hemor-
rhage. Raise the arm on the bleeding side ; do not blow
the nose. Wring two towels in cold water; wrap one
around the neck and the other properly folded over the fore-
head and upper part of the nose. Plug the nostril with a
piece of absorbent cotton which has
been wet with strong borax or alum
water. When the nostril has been
plugged, especially if the patient is a
young child, it is important to make
'jf sure that blood is not trickling down
into the throat from the posterior
nares.

476. Burns or Scalds. Burns or
scalds are dangerous in proportion to
their extent and depth. A deep or
extensive burn or scald should always
^^ have prompt medical attendance.

' M In burns by acids, bathe the parts

jf . with an alkaline fluid, as diluted am-
FIG. 163. Dotted Line monia or strong soda in solution, and
showing the Course 6f afterwards dress the burn.

the Femoral Artery. jn bums causecj by lime, Caustic

potash, and other alkalies, apply lemon juice, vinegar diluted
with water, or any other diluted acid.

Remove the clothing with the greatest care. Do not
pull off the clothes from the burned places, but gently loosen
them or cut them away. Save the skin unbroken if pos-
sible, taking care not to break the blisters. The secret of
treatment is to prevent friction and to keep out the air.

If the burn is slight, put on strips of soft linen soaked
in a strong solution of baking soda and water, one heaping

First Aid to the Injured

307

tablespoonful to a cupful of water. This is especially good
for scalds.

Carron oil is one of the best applications. It is simply
half linseed oil and half limewater shaken together until
they form a cream. Soak strips of old linen or absorbent
cotton in this time-honored remedy, and gently apply.

If carbolized or even plain vaseline is at hand, spread it
freely on strips of old
linen and cover well
the burnt parts, keep-
ing out the air with
other strips carefully
laid on.

477. Frost Bites.
No warm air, warm
water, or fire should be
allowed near the frozen
or frost-bitten parts
until the natural tem-
perature is nearly
restored. Rub the
frozen part vigorously
with snow or snow
water in a cold room.
Continue this until a

burning, tingling pain is felt, when all active treatment
should cease. Pain shows that warmth and circulation
are beginning to return.

478. Setting the Clothing on Fire. When the clothing
catches fire throw the person down on the ground or floor,
as the flames will tend less to rise toward the mouth and
nostrils. Then, without a moment's delay, roll the person
in a carpet or rug, so as to stifle the flames, leaving only

FIG. 164. Showing how Hemorrhage from
the Femoral Artery may be arrested by
the Use of an Improvised Tourniquet.

308 Life and Health

the head out for breathing. If no carpet or rug can be
had, then take off your coat, shawl, or cloak, and use it
instead.

479. Foreign Bodies in the Throat. Bits of food or other
small objects sometimes lodge in the throat, and are easily
extracted by the forefinger, or they may be driven out by
sharp slaps on the back, or expelled by vomiting. If the
object has actually passed into the windpipe, causing sudden
fits of spasmodic coughing, with a dusky hue of the face
and fingers, surgical help must be called without delay.

If a foreign body, like coins, pencils, keys, nails, buttons,
etc., is swallowed, it is not wise to give a physic. Give
plenty of hard-boiled eggs, cheese, and crackers, so that
the intruding substance may be enfolded in a mass of solid
food and allowed to pass off through the bowels.

480. Foreign Bodies in the Nose. Children are apt to
push beans, peas, fruit stones, buttons, and other small
objects into the nose. Sometimes we can get the child
to expel the object by blowing the nose hard. At other
times a sharp blow between the shoulders will cause the

substance to fall out.

481. Foreign Bodies
in the Ear. It is a
much more difficult
matter to get foreign
bodies out of the ear
than from the nose.
Syringe in a little

FIG. 165. Showing how the Upper Eyelid ,. , m

may be everted with a Pencil or Penholder. Wai n water' Wni

often wash out the

substance. If live insects get into the ear, drop in a little
sweet oil, melted vaseline, salt and water, or even warm
molasses.

First A id to the Injured

309

If the tip of the ear is pulled up gently, the liquid will
flow in more readily. If a light is -held close to the out-
side of the ear, the insect
may be coaxed to crawl out,
having been attracted by the
bright flame.

482. Foreign Bodies in the Eye. Cin-
ders, particles of dust, and other small
bodies often get into the eye and cause
much pain. It will only make bad mat-
ters worse to rub the eye. Often the
copious flow of tears will wash the sub-
stance away. It is sometimes removed
simply by the twisted corner of a hand-
kerchief. Oftentimes the upper lid must
be turned back (Fig. 165).

This is done usually as follows : Seize
the lashes between the thumb and fore-
finger and draw the edge of the lid away
from the eyeball. Now, telling the
patient to look down, press a slender
lead pencil or penholder against the lid,
parallel to and above the edge, and
then pull the edge up and turn it over
the pencil by means of the lashes.

The eye is now readily examined,
and usually the foreign body may be
seen and easily removed with the cor-
ner of a pocket handkerchief. After the
substance has been removed bathe the
eye with hot water -until all pain stops.
483, Broken Bones. Broken limbs
should always be handled with great care and tenderness.

FIG. 1 66. Showing how
an Umbrella may be
used as a Temporary
Splint on a Broken Leg.

3io Life and Health

If the accident happens in the woods, the limb should be
bound with handkerchiefs, suspenders, or strips of clothing,
to a piece of board, pasteboard, or bark, padded with moss
or grass, which will do well enough for a temporary splint.
Always put a broken arm into a sling after the splints are on.
Never move the injured person until
the limb is made safe from further
injuries by putting on temporary splints.
If you do not need to move the person,
keep the limb in a natural, easy position
until the doctor comes.

A surgeon is needed at once to set
the broken bone.

484. Fainting. A fainting person
should be laid flat at once. Give plenty
of fresh air, and dash cold water, if neces-
sary, on the head and neck. Loosen all
tight clothing. Smelling salts may be
held to the nose, to excite the nerves
of sensation and thus stimulate respi-
ration.

FIG. 167. Showing how

a Pillow or a Blanket 485- Epileptic and Hysterical Fits,
may be used as a See that the person does not injure him-

Temporary Splint on sdf . crowd a d made from a folded
a Broken Leg. .. . ' .

handkerchief or towel between the
teeth, to prevent biting of the lips or tongue. Do not try
to make the sufferer swallow any drink. Unfasten the
clothes, especially about the neck and chest.

486. Sunstroke or Heat Stroke. The main thing is to lower
the temperature. Strip off the clothing ; apply chopped ice,
wrapped in flannel, to the head. Rub ice over the chest and
place pieces under the armpits and at the sides. If there is
no ice, use sheets or cloths wet with cold water.

First Aid to the Injured 3 1 1

If the skin is cold, moist, or clammy, the trouble is due
to heat exhaustion. Give plenty of fresh air, but apply no
cold to the body. Apply heat and give hot drinks.

487. Asphyxia, or Suspended Animation. The chief
dangers from poisoning by noxious gases come from the
fumes of burning coal in the furnace, stove, or range ;
from " blowing out " gas, turning it down, and having it
blown out by a draught ; from the foul air often found in
old wells or mines ; and from the fumes of burning charcoal.

The first and essential thing to do is to give fresh air.
Remove the person to the open air and place him on his

FIG. 1 68. Production of Artificial Respiration.
(First movement — inspiration.)

back. Remove tight clothing about the throat and waist,
dash on cold water, give a few drops of ammonia in hot
water or hot ginger tea. Friction applied to the limbs
should be kept up. If necessary, use artificial respiration
as described in section 489.

488. What to do in Apparent Drowning. Remove all
tight clothing from the neck, chest, and waist. Sweep
the forefinger, covered with a handkerchief or towel,
round the mouth, to free it from froth and mucus. Turn
the body on the face, raising it a little, with the hands
under the hips, to allow any water to run out from the
air passages. Take only a moment for this.

312 Life and Health

Lay the person flat upon the back, with a folded coat,
or pad of any kind, to keep the shoulders raised a little.
Remove the wet, clinging clothing as far as possible. If
in a room or sheltered place, strip the body and wrap it
in blankets, overcoats, etc. If at hand, use bottles of hot
water, hot flatirons, or bags of hot sand round the limbs
and feet. Watch the tongue ; it generally tends to slip
back and to shut off the air from the glottis. Wrap a
coarse towel round the tip of the tongue and keep it
well pulled forward.

489. How to produce Artificial Respiration. The main
thing to do in apparent drowning is to produce artificial
respiration until the natural breathing comes or all hope is
lost. This is the simplest way to do it : The person lies

FIG. 169. Production of Artificial Respiration.
(Second movement — expiration.)

on the back ; let some one kneel behind the head. Grasp
both arms near the elbows and sweep them upward above
the head until they nearly touch. Make a firm pull for a
moment. This tends to fill the lungs with air by drawing
the ribs up and making the chest cavity larger. Now
return the arms to the sides of the body until they press
hard against the ribs? This tends to force out the air.

First Aid to the Injured 3 1 3

This makes artificially a complete act of respiration. Repeat
this act about fifteen times every minute.

All this may be kept up for several hours. The first
sign of recovery is often seen in the slight pinkish tinge
of the lips or finger nails. That the pulse cannot be felt
at the wrist is of little value in itself as a sign of death.
Life may be present when only the most experienced ear
can detect the faintest heart beat.

When a person can breathe, even a little, he can swallow.
Hold smelling salts or hartshorn to the nose. Meanwhile
do not fail to keep up artificial warmth in the most vigorous
manner.

POISONS AND THEIR ANTIDOTES

490. Irritant and Narcotic Poisons. For convenience
poisons may be divided into two classes, irritants and
narcotics.

The effects of irritant poisons are evident immediately
after being taken. They burn, or corrode, the skin or mucous
membrane or other parts with which they come in contact.
They produce burning pains in the mouth, throat, stomach,
and intestines, with nausea and vomiting.

With narcotic poisoning the symptoms come on more slowly.
After a time there is drowsiness, which gradually increases
until there is a profound sleep or stupor, from which the
patient can be aroused only with great difficulty. There
are some substances which possess both the irritant and
narcotic properties and in which the symptoms are of a
mixed character.

491. Treatment of Poisoning. In the treatment of poison-
ing the first thing to do, if you know the special poison, is to
give its antidote at once. An antidote is a substance which will
either combine with a poison to render it harmless or which
will have a directly opposite effect upon the body, thus neu-
tralizing the effect of the poison.

If the poison is unknown, or there is any delay in obtain-
ing the antidote, the first thing to do is to cause vomiting as

314 Life and Health

quickly as possible. This may be done by stirring a table-
spoonful of mustard or of common salt in a glass of luke-
warm water and making the patient swallow the whole.
Repeat as often as is necessary. Vomiting may be hastened
by thrusting the forefinger down the throat.

For some poisons, as acids and alkalies, no emetic should
be given. Again, for poisons like carbolic acid, which cause
local irritation, but which also affect the system at large, no
emetic should be given. An emetic, however, should be given
in the case of arsenic.

492. Practical Points about Poisons. Poisons should never
be kept in the same place with medicines or other prepara-
tions used in the household. They should always be put in
some secure place under lock and key. Never use internally
or externally any part of the contents of any package or
bottle unless its exact nature is known. If there is the least
doubt about the substance, do not assume the least risk, but
destroy it at once. Many times the unknown contents of some
bottle or package have been carelessly taken and found to be
poison.

Careless and stupid people often take by mistake, with
serious, and often fatal, results, poisonous doses of carbolic
acid, insect poison, horse liniment, oxalic acid, and other
poisons. A safe rule is to keep all bottles and boxes con-
taining poisonous substances securely bottled or packed, and
carefully labeled, with the word POISON plainly written in
large letters across the label. Fasten the cork of a bottle
containing poison to the bottle itself with copper wire twisted
into a knot at the top. This is a simple but effective means
of preventing any mistakes which are likely to be made by
children or in darkness.

This subject of poisons assumes nowadays great impor-
tance, as it is a common custom to keep about stables,
workshops, bath rooms, and living rooms generally a more
or less formidable array of disinfectants, horse liniments,
insect destroyers, and other preparations of a similar charac-
ter. For the most part, they contain poisonous ingredients.

First Aid to the Injured

315

A TABLE OF THE MORE COMMON POISONS

With their prominent symptoms, antidotes, and treatment

Poison

Strong Acids:
Muriatic
Nitric

Sulphuric (vitriol)
Oxalic

Alkalies:

Caustic potash and

soda

Ammonia
Lye
Pearlash

Prominent Symptoms

Burning sensation in
mouth, throat, and stom-
ach ; blisters about mouth ;
vomiting ; great weakness

Burning sensation in the
parts ; severe pain in stom-
ach ; vomiting ; difficulty
in swallowing; cold skin;
weak pulse

Antidotes and
Treatment

No emetic. Saleratus ;
chalk; soap; plaster from
the wall ; lime ; magnesia ;
baking soda (3 or 4 tea-
spoonfuls in a glass of
water)

No emetic. Olive oil
freely ; lemon juice ; vine-
gar ; melted butter and
vaseline; thick cream

Arsenic:
Paris green
Rough on rats
White arsenic
Fowler's solution
Scheele's green

Other Metallic
Poisons :
Blue vitriol
Copperas
Green vitriol
Sugar of lead
Corrosive sublimate
Insect poison

Phosphorus from
Matches, rat poisons,
etc.

Intense pains in stom-
ach and bowels ; thirst ;
vomiting, perhaps with
blood ; cold and clammy
skin

Symptoms in general,
same as in arsenical poi-
soning. With lead and
mercury there may be a
metallic taste in the mouth

Pain in the stomach;
vomiting ; purging ; gen-
eral collapse

Vomit patient repeat-
edly; give hydra ted oxide
of iron with magnesia, usu-
ally kept by druggists for
emergencies ; follow with
strong solution of common
salt and water

Emetic with lead ; none
with coppar and iron ; white
of eggs in abundance with
copper ; with iron and lead
give Epsom salts freely;
afterwards, oils, flour, and
water

No emetic -with mercury ;
raw eggs; milk, or flour
and water

Cause vomiting. Strong
soapsuds ; magnesia in
water. Never give oils

316

Life and Health

Poison
Opium :

Morphine
Laudanum
Paregoric
Dover's powder
Soothing syrups, etc.

Carbolic Acid:
Creosote

Aconite:
Wolfsbane
Monkshood

Prominent Symptoms

Sleepiness ; dullness ;
stupor; "pinhole" pupils;
slow breathing ; profuse
sweat

Severe pain in abdomen ;
odor of carbolic acid, mu-
cous membrane in and
around mouth white and
benumbed ; cold, clammy
skin

Numbness everywhere ;
great weakness ; cold sweat

Antidotes and
Treatment

Cause vomiting. Keep
patient awake by any
means, especially by vig--
orous walking ; give strong
coffee freely; dash cold
water on face and chest

No emetic. M ilk, or flour
and water ; white of eggs

Vomit patient freely.
Give strong coffee freely.

Belladonna:

Deadly nightshade
Atropia

Various Vegetable
Poisons:

Wild parsley
Indian tobacco
Tobacco plant
Hemlock, etc.

Eyes bright, with pupil
enlarged; dry mouth and
throat

Stupor, nausea, great
weakness and other symp-
toms according to the poi-
son

Vomit patient freely

Cause brisk vomiting.
Give strong coffee freely.

NOTE. — The teacher or student who is disposed to study the subject of " First
Aid to the Injured " more thoroughly and in more detail than is possible in a class
text-book will find all the material that is needed in several excellent books. These
books are readily obtained by purchase, or may be found in the public libraries of
larger towns.

CHAPTER XV

THE CAUSE AND PREVENTION OF TUBERCULOSIS
OR CONSUMPTION

493. Consumption a Widespread and Deadly Disease.

Of all diseases known to mankind, consumption, often called
the " great white plague," is without doubt the most wide-
spread and the most deadly. For short periods other diseases,
like " black death " and cholera, have caused more dread and
even wider destruction, but consumption has been the most
constant and the most deadly of all.

Consumption is more common in certain climates and
among certain races, but it spares no nation, no age, no
occupation, and no class of people. It is said that of all people
who die every year, about one seventh die from this disease.
It is estimated that over 150,000 people die of consumption
every year in the United States, and that 1,000,000 lives are
annually lost by this disease in Europe.

494. Consumption a very Old Disease. Consumption is
a very old disease. Evidences of tuberculosis have been dis-
covered even in the old Egyptian mummies. Famous writers
of ancient times, whose writings may still be read, give us
graphic pen pictures of this disease. It was then known, as
it is now, as the " great white plague."

During what is known as the Dark Ages this dread disease
swept through Europe and destroyed people by thousands.
Consumptives were shunned and avoided as if they had
smallpox. They were confined in rooms with the doors and

318

Life and Health

windows closed. Fresh air and sunlight, things which we now
know are so important in curing the disease, were shut out.

495. What is Tuberculosis or Consumption? "Tubercu-
losis " and " consumption " are two names for one disease. It
is caused by a germ or microbe spoken of as the tubercle bacillus
or consumption germ. This germ is a very tiny plant. It is
so small that it would take 3000 put end to end to measure

one inch. This germ does not
readily grow outside of living
bodies ; but when it gains
entrance into the body, it may
grow and multiply. At last it
destroys the tissues and thus
causes the disease usually
spoken of as tuberculosis.

The germ which causes
tuberculosis was discovered by
Dr. Robert Koch (Koke\ a
famous German physician, in
the year 1882. He showed that
a special germ (tubercle bacil-
lus) was always present in every
case of tuberculosis. Up to this
time nobody knew what was the real cause of consumption.
This great discovery has made possible the present wide-
spread crusade against this infectious disease.

496. What Parts of the Body may be attacked by Tuber-
culosis ? Any tissue or organ of our bodies may be infected
by the consumption germ. The name given to this disease
depends upon the tissue or organ attacked. Thus, " hip dis-
ease " is tuberculosis of the hip ; " white swelling " of the
knee, tuberculosis of the knee; and "lupus," a skin dis-
ease, tuberculosis of the skin. The most common form of

FIG. 170. Dr. Robert Koch,
Discoverer of the Tubercu-
losis Germ.

The Cause and Prevention of Tuberculosis 319

tuberculosis, however, is that of the lungs, known generally
as " consumption." Thus when we speak of tuberculosis, we
usually mean consumption.

497. How the Germs of Consumption do their Work. The
presence of the tubercle bacillus in the body does not always
cause consumption.

When the germs of
this disease get into
the body, a contest
seems to take place
between these germs
and the cells of which
the body is composed.
If the germs gain the
victory, little tumor-
like knots, not unlike
the tiniest grains of
sand, called tubercles,
are formed. After a
time these tubercles
in the lungs soften
and break down.
The matter of which
they are composed
is coughed up into the mouth and is known as sputum.
This matter thus coughed up often contains millions of
tubercle baccilli and is therefore dangerous to the health of
other .people. It has been estimated that in the sputum
of one consumptive there may be more than twenty-four
millions of these germs in the course of twenty-four hours.

498. How Consumption is regarded as a Contagious Dis-
ease. We must remember that consumption is not contagious
in the sense in which we speak of scarlet fever, smallpox,

FIG. 171. Germs of Tuberculosis.

(A minute portion of sputum from a case of phthisis,
or consumption, magnified 1000 diameters. These
germs are rod-shaped bacteria, stained to show
black. The black spots in the figure are merely
the debris in the sputum, also stained to look black.)

320 Life and Health

measles, and so on, as being "contagious." We do not get
consumption from being in contact with a person suffering
from it or from his breath, but only by breathing in for a
longer or shorter time the germs from the matter coughed
up (sputum), or by means of food or drink which has been
infected with the consumption germs.

It is cruel and senseless to shun or neglect a consumptive
for fear of catching the disease. Much needless pain has been
inflicted upon the sick and suffering in so doing. A consump-
tive should be safe and harmless to work or live with, if he is
cleanly in his habits, is careful in properly disposing of his
sputum, and uses cloths or paper napkins before his mouth
when coughing. There is no reason why a consumptive who
carefully observes the precautions as set forth in this chapter
should be shunned or neglected as dangerous.

499. How Consumption Germs are scattered by Persons.
The germs of tuberculosis are scattered by consumptive per-
sons in many different ways. The commonest and most
important way is by the matter that leaves the mouth and
nose. The germs are present in the matter that is coughed
up by persons who have consumption of the lungs, and also
in the tiny drops of fluid sprayed from the mouth and nose
of such persons during coughing, sneezing, and talking.

The germ-laden substance from the mouths of consump-
tives may cling to glasses, cups, towels, napkins, handker-
chiefs, spoons, sheets, pillowcases, slates, slate pencils, toys,
and numerous other articles.

Tubercle bacilli are also scattered in the dust of dried
sputum.

Drinking from glasses or cups without thoroughly cleaning
them after they have been used by others is a practice through
which not only consumption but also diphtheria, scarlet fever,
and some other diseases may be communicated.

The Cause and Prevention of Tuberculosis 321

500. The Chief Mode of communicating Consumption.

The chief mode of communicating consumption is by the
dried sputum of consumptives. The germs of this disease
exist by the million in the sputum which may be hawked or
coughed up and cast upon the sidewalk, the floors of public
halls, schoolrooms, workshops, and public buildings, or upon

FIG. 172. Louis Pasteur (1822-1895).

(This picture represents Pasteur, the great master of modern science,
busily at work in his laboratory recording the results of his study
of bacteria.)

the floors or carpets in dwelling houses. In fact, any place
where the consumptive may choose to spit may become
infected.

When the sputum becomes dried, the germs which it con-
tains in countless numbers mingle with the air and dust. It
may thus infect susceptible persons and spread the disease to
many. The danger of infection is increased by the great
vitality of the germs, which exist for a long time after drying
and mixing with the dust.

322 Life and Health

The germs of consumption may often be found in the dust
and dirt of overcrowded tenement houses and other dwelling
places. In such places the germs may retain their vitality for many
weeks. Darkness, dampness, cast-off clothing, dirt, and dust
all serve as abiding places for consumption germs.

According to Pasteur and the more recent experiments of
other scientists, even the earthworm plays a very important
part in bringing to the surface disease-producing bacteria.
The studies of these men refer especially to Koch's bacillus
of tuberculosis. Hence cremation, in all cases of death from
infectious diseases, has often been advocated by sanitarians.
In recent years the experiments of scientists have shown that
tuberculosis should be included among such diseases. In
brief, it has been demonstrated conclusively that the con-
sumption germ (tubercle bacillus) can resist putrefaction
for years and be brought to the surface by the seemingly
innocent earthworm.

501. Some of the Early Symptoms of Consumption. Con-
sumption is usually a slow, insidious disease, the germs of
which may be in the body a long time before they cause a
noticeable change from health. Later on they cause general
weakening, loss of appetite, a more or less severe cough,
bleeding from the lungs, loss of flesh and strength, and other
symptoms by which it is easily recognized. Cough is not
always one of the early symptoms of consumption.

It is important that consumption should be recognized in
its early stage, because the longer the disease is neglected
the more difficult it is to cure.

502. Consumption is not inherited. Consumption is not
inherited. It is the tendency which is inherited, but not the
disease itself. In other words, consumptive parents may have
children who are naturally of a poor constitution, with weak
lungs, flat chests, and little or no power to resist infection.

The Cause and Prevention of Tuberculosis 323

Children in such families should be brought up with the
utmost care, and should be given the greatest amount of
fresh air and sunlight.

503. Tuberculosis in Animals. Tuberculosis is not only
the most widely spread of all diseases affecting human beings,
producing a greater mortality than any other, but there is
probably no disease which affects domestic animals so widely.
The disease is most common in cattle ; it is quite common
in pigs, but rare in sheep.

Tuberculosis in fowls is a common and very infectious
disease. Frequently nearly all the birds in a poultry yard are
affected. It is now held to be an established fact by many
scientific men that tuberculosis is transmissible from cattle to
human beings, and that the milk of tuberculous cows is a
common vehicle of transmission.

504. The Crusade against Consumption. The battle against
consumption is now being fought at a lively pace throughout
the civilized world. No disease is receiving such general
attention at the present time as is the "great white plague."
Nations, states, cities, and towns are all actively lending a
hand in the crusade. The campaign is directed not only
against the germ of consumption but quite as much against
the numberless conditions which produce the favorable soil
in the individual.

* In the crusade against consumption numerous agencies,
both public and private, are now at work in the effort to con-
trol and prevent the disease. There is not a state nor territory
in the United States which has not considered or taken action
on the subject of tuberculosis.

In the year 1908, of 43 legislatures in session, 36 debated
on matters pertaining to tuberculosis. A total of more than
$4,000,000 has been appropriated for the conduct of state
campaigns against this disease, and millions more have been

324 Life and Health

granted by cities for the same purpose, to say nothing of the
vast sums given by private subscription for the suppression
of the white plague.

505. Various Agencies at Work in this Crusade. The
campaign against consumption in the various states is along
two lines : First, that which is done by sanatoriums and

FIG. 173. Outdoor School for Consumptive Children,
Franklin Park, Boston.

(Chair bags of weatherproof canvas lined with blanketing, and special
ulster coats, wool mittens, and stockings and overshoes keep the
children warm in all weathers.)

hospitals ; second, that which is being done outside of these
institutions by medical men, boards of health, anti-tuberculo-
sis associations, and so on, in teaching people how to live in
their own homes.

Almost every country has one or more public sanato-
riums for the relief of early, curable cases. In this country

The Cause and Prevention of Tuberculosis 325

sanatoriums in the various states are rapidly .increasing. In
all of the large cities, and in many of the smaller cities and
towns in some states, various anti-tuberculosis associations
have been formed.

Dispensaries for the free examination and treatment of
the poor who are sick with consumption have been estab-
lished and are maintained at the public expense in almost all
large cities.

Hospitals for the isolation and care of advanced cases of
consumption are being rapidly established. Nothing is more
important in the prevention of tuberculosis than the isolation
in hospitals for consumptives of advanced cases which cannot
be safely treated at home.

506. Day Camps, Open- Air Schools, and Seaside Sana-
toriums. The " day camp " is now a popular and very valu-
able method of treating consumptive patients who cannot go
away from home. They come to the camp every morning,
spend the day out of doors, receiving good food and medical
supervision, and return to their homes at night. The " night
camp " is also being introduced, where patients who are
obliged to work by day can spend the night under open-air
conditions.

Open-air schools, called " forest schools" in Germany, are
like the day camp with the addition of daily lessons. These
schools are held in the summer out of doors, in winter in
buildings with wide-open windows. The children are dressed
warmly and are provided with proper food during the day.

It has been proved that sea air and sea bathing are very
beneficial for children sick with consumption. Many sana-
toriums for such cases have been established on the seacoast
in Europe. In this country the " Sea-breeze Hospital " at
Coney Island has become well known for its good work in
behalf of consumptive children.

326

Life and Health

507. The Outdoor Life. The outdoor life is one of the
great essentials in the treatment of consumption. It is in
striking contrast to the common indoor existence of most
city people. The patient is out of doors from seven to ten
hours every day, at rest a part or the whole of the time. He
also sleeps out of doors, or with the windows of his sleeping
room wide open, whatever the weather or temperature.

FIG. 174. The Open-Air Treatment of Tuberculosis.
Service of Dr. J. H. Pratt, Boston.

(This consumptive patient is taking the treatment in a canvas tent,
in a vacant lot in the rear of his home. The tent is converted into
a canopy by fastening up the sides and ends.)

Outdoor sleeping is advised, and is now frequently prac-
ticed by those in good health as well as by the consumptive.
For this purpose either a piazza, a so-called "shack" (which
is a small open building), or a sleeping porch (which can be
added to almost any house at a small expense), may be made
use of.

Outdoor conditions of sleeping may also be obtained by
means of the "window tent," which can be applied to any
window, and by this device the body remains indoors while

The Cause and Prevention of Tuberculosis 327

the head is practically out of doors. With proper protection
one can be comfortable even in winter weather.

508. The Education of the General Public. It is by these
agencies that we have just spoken of, and many others which
space does not allow us to refer to, that the prevention and
control of tuberculosis is being accomplished.

By means of tuberculosis clinics and district nurses the in-
numerable cases of consumption in homes, in overcrowded
tenement houses, and in factories and workshops are being
found out. The early cases are urged to go to the various
state sanatoriums.

Proper hospital accommodation is obtained for the advanced
cases, or they are taught how to live in their own homes.
The masses of the people are educated by means of lectures,
exhibits, cards and signs, etc. Boards of health are stimulated
to take proper measures as regards disinfection.

Physicians are urged to report their cases of consumption
as they do their cases of scarlet fever and diphtheria. Best
of all, the general, public is aroused to realize the importance
of the subject.

509. Suggestions on protecting your Health against
Consumption, i. All nose and throat troubles, a cough
which has lasted for some time, or a sudden loss of flesh
and strength, should lead you to seek medical aid.

2. Insist upon having plenty of fresh air in your sleep-
ing room, both day and night, in summer and winter.

3. Open the windows in all the living rooms often. Let
in the sunlight.

4. Stay out of doors whenever you can. A balcony may
be fitted up for both sitting and sleeping purposes. Chil-
dren should live as much as possible in the open air. Every
form of sport should be encouraged which tends to keep
them there.

328 Life and Health

5. A person who is ill with tuberculosis should be kept
in the open air for at least several hours each day, in spite
of fever or cough, although it is important that he should
be kept warm. Sudden, unnecessary exposure to extreme
changes in the weather should be avoided.

6. Wear light underwear of moderate weight, and put on
outside wraps according to changes in the weather.

7. Bathe the neck and chest, front and back, with cold
water every morning. After bathing rub the skin well with
a coarse towel.

8. Spend your money for good food rather than for
medicines. Patent medicines, or proprietary preparations, or
drugs of any kind should not be taken internally without the
advice or consent of a physician in good standing.

9. Avoid fatigue. If you are working, lie down when
you have a few moments to spare.

10. Remember that many persons who have suffered with
tuberculosis are now well, and that the disease is no longer
regarded as incurable.

1 1 . Do not spit on the sidewalk, the crosswalk, or on the
floor of any building, street car, or other public conveyance
where the sputum may become dry and permit the spread of
the germs which it may contain. Join the anti-spit crusade.
Favor the enactment and enforcement of laws prohibiting spit-
ting on sidewalks, on floors, in street cars or other conveyances.

510. How may School Children help in the Crusade
against Consumption. Every child and grown-up person can
help in the crusade against consumption. School children
can be helpful by heeding the following suggestions :

Do not spit except in a spittoon, a piece of cloth, or a
handkerchief used for that purpose alone. On your return
home have the cloth burned, or the handkerchief put in
water until ready for the wash.

The Cause and Prevention of Tuberculosis 329

Never spit on a slate, floor, playground, or sidewalk.

Do not wet the fingers in the mouth for the purpose of turn-
ing the leaves of books, especially library or school books, as
book leaves are
sometimes the
lurking places of
germs of disease.

Do not put pen-
cils in your mouth
or wet them with
your lips.

Do not hold
money in your
mouth. This is
extremely im-
portant, because
money is liable
to come in contact
with all sorts of
people and to be-
come contami-
nated with many
kinds of disease-
producing bacteria.

Do not put into
the mouth any-
thing that another
person has had in
his mouth. This

FIG. 175. The Open- Air Treatment of Tuberculosis.
Service of Dr. J. H. Pratt, Boston.

(The porch in this cut was built at small cost for a con-
sumptive patient who wished to sleep out of doors but
did not wish to use the yard or a porch off the first floor.
On a similar balcony a patient who had advanced tuber-
culosis spent most o'f the day and slept every night for
a year. He gained sixty pounds in weight while taking
the open-air treatment.)

refers to gum, apple cores, candy, whistles, bean blowers,
drinking cups, and many other things.

Never sneeze or cough in a person's face. Turn your face
to one side or hold a handkerchief before your mouth.

3 30 Life and He a Ith

Learn to love fresh air and learn to breathe deeply and
do it often. %

Even a knife or a spoon coming from the sick room should
be placed in boiling water before it is used by any other
person. Water that is simply hot is not sufficient for this
purpose. The water must be boiling, and it is better if the
articles are placed in the water and the water boiled for five
or ten minutes before they are taken out to be used.

NOTES

For additional material on tuberculosis, either for reading or for refer-
ence, the student and teacher are referred to the following books and
pamphlets, as the most useful and practical for these purposes :

The Great White Plaice: Tuberculosis, by Dr. Edward O. Otis. 321 pages.
T. Y. Crowell & Co., Publishers, New York. Price, $1.00.

Tuberculosis : A Preventable and Curable Disease, by Dr. S. Adolphus Knopf.
Fully illustrated. 394 pages. Moffat, Yard & Co., Publishers, New York.
Price, $2.00.

The Conquest of Consumption, by Dr. Woods Hutchinson. Illustrated. 138
pages. Houghton Mifflin Company, Publishers, Boston. Price, $1.00.

The Open-Air Treatment of Pulmonary Tuberculosis, by F. W. Burton-
Fanning. Illustrated. 184 pages. Paul B. Hoeber, Medical Publisher,'
69 East 59th St., New York. Price, $1.50.

These four books may be found in public libraries, should be provided
by local anti-tuberculosis associations, or may be ordered through any
local bookseller.

Teachers may consult with profit Allen's Civics and Health, espe-
cially Chapter XXIV, " The Last Days of Tuberculosis." Ginn & Com-
pany, Publishers, Boston. Price, $1.25.

A notable pamphlet, " The Cause and Prevention of Consumption,"
has been issued by the Illinois State Board of Health. Copies of the
latest edition may be obtained by any resident of Illinois, without cost,
by addressing the secretary at Springfield.

A most useful little pamphlet, "Tuberculosis and its Prevention,"
with suggestions to teachers, has been issued by the Massachusetts Board
of Education. This will be sent gratis to teachers upon application at the
statehouse, Boston.

For information on the subject of tuberculosis, sundry pamphlets
issued by the Boston Association for Relief and Control of Tuberculosis
may be obtained on application at the office of the association, 4 Joy
Street, Boston, at a nominal price.

For information concerning a most admirable series of booklets on
matters of health, including tuberculosis, correspondence is suggested
with the Health-Education League, 113 Devonshire St., Boston. These
booklets are sold at a nominal price.

331

APPENDIX

EXPERIMENTAL WORK IN PHYSIOLOGY IN HIGHER
SCHOOLS

1. The Experimental Method of Instruction. Every experienced
teacher knows that pupils gain a far better knowledge and keep up
a livelier interest in any branch of science, if they are able to see
with their own eyes and to do with their own hands that which serves
to illuminate and illustrate the particular branch of science in which
they are engaged.

The experimental method of instruction rivets the attention and
arouses and keeps alive the interest of the young student ; in
fact, it is the only true method of cultivating a scientific habit of
study.

2. Experimental Work in Physiology in Elementary Schools.
Unlike other branches of science taught in elementary schools from
the experimental point of view, the study of physiology has its limi-
tations. The scope and range of such experiments is necessarily
extremely limited compared with what may be done with the costly
and elaborate apparatus of medical laboratories.

The study of anatomy and physiology is based upon the system-
atic and painstaking dissection of the dead human body and of the
lower animals, together with experiments upon living animals. This
plan of research and study very properly is not permitted in elemen-
tary school work. Experiments upon the living human body and the
lower animals, now so generally depended upon in our medical and
more advanced scientific schools, for obvious reasons can be per-
formed only in a crude and quite superficial manner in high, and
normal schools.

3. Importance of Experiments in Physiology in Higher Schools.
While circumstances and regard for certain proprieties of social life
forbid a range of experiments in anatomy and physiology such as is

333

334 Life and Health

permitted in other branches of science in secondary schools, it by no
means follows that we are shut out altogether from this most impor-
tant and interesting part of the study. However simple and crude
the apparatus, the skillful and enthusiastic teacher has at his com-
mand a wide range of materials which can be profitably utilized for
experimental instruction.

The subject-matter as set forth in the preceding chapters of this
book should be mastered, of course, but at the same time the topics
discussed should be illuminated and made more interesting and prac-
tical by the series of experiments given in connection with the several
chapters, a goodly show of specimens, and a certain amount of micro-
scopical work.

4. Costly Apparatus by no Means Necessary. It will be noticed
that many of the experiments in this book can be performed with
very simple and often crude and homemade apparatus. This plan
has been rigidly followed by the author, first, because he fully realizes
the limitations and restrictions of the subject ; and secondly, because
he wishes to emphasize the fact that expensive and complicated appa-
ratus is by no means necessary to illustrate the great principles of
anatomy and physiology.

In schools in which both the funds and the time for experimental
work are limited, the zeal and ingenuity of teachers and students are
often put to a severe test. Fortunately, a very little money and a
great deal of ingenuity and patience will do much towards providing
a working supply of apparatus.

5. Use of the Microscope. The appearance of the various struc-
tures and tissues of the human body as revealed by the microscope
possesses a curious fascination for every observer, especially for
young students. No one ever forgets the first look at a drop of
blood, or the circulation of blood in a frog's foot as shown by the
microscope.

For elementary class work a moderate-priced but well-made and
strong instrument should be provided. If the school does not own
a microscope, the loan of an instrument should be obtained for at
least a few weeks from some person in the neighborhood.

To do thorough and satisfactory work in physiology in our higher
schools a compound microscope is almost indispensable. Inasmuch
as many of our best secondary schools are equipped with a micro-
scope for use in other studies, notably botany, it is much less difficult

Appendix

335

than it was a few years ago to obtain this important help for the
classes in physiology.1

6. Vivisection and Dissection. There should be no question at all
concerning vivisection. In no shape or form should it be allowed
in any grade of our schools. Nor is there

any need of much dissection in the elementary
grades. A few simple dissections which can
be made with fresh beef-joints, and legs of
chickens and turkeys, will never engender
cruel or brutal feelings toward living things.
A discreet teacher should rarely advise his
pupils to dissect a dead cat, dog, frog, or
any other animal. Instead of actual dissec-
tion, the pupils should examine specimens or
certain parts previously dissected by the
teacher, — as the muscles and joints of a
sheep, the heart of an ox, the eye of a codfish,
and so on. Even under these restrictions the
teacher should rarely use the knife or' scis-
sors before the class to open up any part of
the specimen.

Most teachers will find, however, even in
schools of a higher grade, that the whole sub-
ject is fraught with many difficulties. A
teacher's good sense and discretion are often
put to a severe test to avoid unjust and sense-
less criticism, which is often easily aroused
in any community.

7. Surface Anatomy and Landmarks of the
Body. In our leading medical colleges the

students are carefully and thoroughly drilled FIG. 176. A Compound
on a study of living models. The object is Microscope.

1 For detailed suggestions in regard to the manipulation and use of the
microscope the student is referred to any of the standard works on the
subject. The catalogues of scientific-instrument makers generally furnish
a list of the requisite materials or of handbooks which describe the use of
the various microscopes of standard make.

For the names and addresses of firms that deal with microscopes and
apparatus for experiments the reader is referred to the advertising pages
of leading scientific or educational publications.

336 Life and Health

to master by observation and manipulation what is known as surface
anatomy and landmarks. Now while detailed work of this kind is
not desirable in secondary schools, yet a limited amount of study
along these lines is deeply interesting and profitable. The habit of
looking at the living body with anatomical eyes and with eyes at our
fingers' ends, during the course in physiology, cannot be too highly
estimated.

In elementary work it is only fair to state that many points of sur-
face anatomy and many of the landmarks cannot always be defined
or located with precision. A great deal in this direction can, how-
ever, be done in higher schools with ingenuity, patience, and a due
regard for the feelings of all concerned. For example, the student
may be taught to examine the muscles and other parts of his own
face, his teeth, tongue, and palate, and the bones and muscles of his
shoulders and limbs. Two friends may thus work together, each
serving as a "model" to the other.1

8. Books for Collateral Reading in Experimental Work in Physiology.
A number of books, prepared for the use of teachers and students in
schools who wish to supplement the text-book with experimental work,
have been recently published. Of these books the teacher is advised
to use these excellent handbooks : Prudden's Dust and its Dangers
and The Story of Bacteria (G. P. Putnam's Sons) ; Tracy's Hand-
book of Sanitary Information (Appleton & Company) ; Woodhull's
Homemade Apparatus (E. L. Kellogg & Company); Bowditch's
Hints for Teachers of Physiology (D. C. Heath & Company); Pea-
body's Laboratory Exercises in Anatomy and Physiologv (H. Holt
& Co.) ; Brown's Physiology for the Laboratory (Ginn & Company) ;
and French's Manual of Dissection and Histology (J. B. Lippincott
Company).

1 For a syllabus of a very brief course of study on the living model see
BlaisdelPs Practical Physiology, pp. 415-419.

GLOSSARY

[Many words that are defined or explained as they occur in the text of this book,
or the meaning of which is readily understood, have been omitted in this Glossary.]

Ab-do'men (Lat. abdo, abdere, to conceal). The largest cavity of the body,
containing the liver, stomach, intestines, and other organs.

Ab-duc'tor (Lat. abducere^\.Q draw from). A muscle which draws from the
median line of the body or other median line.

Ab-sor'bent (Lat. absorbere, to suck up). An organ or part that absorbs;
a lymphatic vessel.

Ab-sorp'tion. The process of sucking up nutritive or waste matters by
the blood vessels or lymphatics.

Ac-com/mo-da/tion of the eye. The alteration in the shape of the crystal-
line lens, which adjusts the eye for near vision.

Ac-e-tab'u-lum (Lat. acetabulum, a small vinegar cup). The cup-shaped
cavity of the innominate bone which receives the head of the femur.

A-cro'mi-on (Gr. Axpov, the tip, and w/xos, the shoulder). The part of the
scapula forming the tip of the shoulder.

Ad-duc'tor (Lat. adducerc, to draw to). A muscle which draws towards the
median line of the body or other median line.

Af'fer-ent (Lat. ad, to, and ferre, to convey). Vessels or nerves carrying
the contents or impulses towards the center.

Al-bu'men (Lat. albus, white). Formerly used as a synonym for proteid,
now rarely used.

Al-bu'min (Lat. albus, white). A class of proteids, as egg-albumin, serum-
albumin, etc.

Al-bu/mi-nu/ri-a. Presence of albumen in the urine.

Al-i-men'ta-ry (Lat. alimentum, food). Pertaining to aliment, or food.

Al-i-men'ta-ry ca-nal' (Lat. alimentum). The digestive tube from the lips
to the end of the rectum.

Arka-li (Arabic al kali, soda-ash). Certain substances, such as soda,
potash, and the like, which unite with acids to form salts.

337

338 Life and Health

Al-ve'o-lus, pi. alveoli (Lat. alveolus, a little hollow). A small cavity, or

socket, as the sockets for the teeth in the jawbone, the air sacs of the

lungs, and the secreting recesses of certain glands.
A-mce'ba (Gr. d/iot/3^, a change). A single-celled, protoplasmic organism,

which is constantly changing its form by protrusions and withdrawals

of its substance.

A-mce'boid. Like an amoeba in form or in movement.
Am-puria (Lat. ampulla, a wine flask). The dilated part of the semi-
circular canals of the internal ear.
Am'y-lop'sin (Gr. &/JLV\OV, starch, and 6\f/is, appearance). A ferment found

in the pancreatic juice, which changes starch into sugar.
A-nab'o-lism (Gr. ava.pd\\eiv, to throw or build up). The process by which

simpler elements are built up into more complex.
An'aes-thet'ic (Gr. &v, without, and alae-rjcria, feeling). A substance which

produces insensibility to pain or to touch, etc., as chloroform, ether, etc.
An'ti-dote (Gr. avri, against, and 8i86vai, to give). A substance given to

prevent or counteract the action of a poison.
An'ti-sep'tic (Gr. avrl, against, and <rri\j/is, poison). A remedy or agent

which prevents the development of bacteria, or prevents the growth of

bacteria upon which putrefaction depends.
An'ti-tox'in (Gr. avri, against, and ro|t/c6i', poison). A substance which

neutralizes the action of the toxins of bacteria. Antitoxins are used in

the treatment of certain infectious diseases, like diphtheria.
An'trum (Lat. antrum, a cave). The cavity in the upper jaw.
Ap'o-neu-ro'sis (Gr. d?r6, from, and vevpov, a nerve). A fibrous, membranous

expansion of a tendon.
Ap'pa-ra'tus. Used to designate collectively organs which perform a

certain function.
Ap-pen/di-ci/tis (Lat. appendix, and if is). Inflammation of the appendix

vermiformis of the caecum.
A'que-ous hu'mor (Lat. aqua, water). The watery fluid occupying the

space between the cornea and crystalline lens of the eye.
A-racb/noid mem'brane (Gr. dpdxvi], a spider, and eTSos, form). The thin

covering of the brain and spinal cord, between the dura mater and the

pia mater.
Ar'bor vi'tse. Literally, "the tree of life"; a name given to the tree-like

appearance of a section of the cerebellum.
A-re'o-lar tis'sue (Lat. areola, a small space, dim. of area). Connective

tissue containing small spaces.
Ar-tic'u-la'tion (Lat. articulus, a joint). The more or less movable union

of bones, etc. ; a joint.

Glossary 339

A-ryt'e-noid car'ti-lages (Gr. dptrcuva, a ladle). Two small cartilages of
the larynx, resembling the mouth of a pitcher.

As-phyx'i-a (Gr. d, without, and 0-<£tf£i5, the pulse). Suffocation. The sus-
pension of vital phenomena when the lungs are deprived of oxygen.

As-sim'i-la'tion (Lat. ad, to, and similis, like). The conversion of food
into living tissue.

A-stig'ma-tism (Gr. d, without, and (rrfywct, a point). Irregular refraction
of the eye, producing a blurred image.

At'ro-phy (Gr. d, without, and rpo^, nourishment). Wasting of a part
from lack of nutrition.

Ba-cirius (Lat. dim. of baculum, a staff). Microscopic, rod-shaped form

of bacteria.

Bac-te'ri-a (Gr. fiaKT-ripiov, a little staff). A microscopic, vegetable organism.
Bac-te'ri-cide (bacterium and Lat. caedere, to kill). An agent that destroys

bacteria.

Bi-oro-gy (Gr. filos, life, and \6yos, a discourse). The science of life.
Blad'der (Saxon bleddra, a bladder, a goblet). A bag, or sac, serving as a

receptacle of some secreted fluid, as the gall bladder, etc.
Blight's dis-ease'. Disease of the kidneys, first described by Dr. Bright, an

English physician.

Bron-chi'tis. Inflammation of the bronchial tubes.
Bur/sa. A small sac interposed between parts that move upon one another.

Callus (Lat. callus, hardness). An excessive hardness of the skin caused

by friction or pressure ; the tissue which unites parts of a broken bone.
Cap'il-la-ry (Lat. capillus, hair). A minute vessel, as those that connect

by a network the arteries and veins.

Cap'sule (Lat. capsula, a little chest). A receptacle, or bag.
Car'bon di-ox'ide. A gas produced in the respiration of animals, and in

the decay or combustion of organic matter. Often called carbonic acid.
Car'di-ac or/i-fice (Gr. KapSia, the heart). The orifice of the stomach, near

the heart.

Car'ron oil. A mixture of equal parts of linseed oil and lime water.
Car'ti-lage. Gristle. A tough but flexible connective tissue forming a

part of the joints, air passages, nostrils, ears, etc.
Car'un-cle (lach'ry-mal) (Lat. caro, flesh). The small, red, conical-shaped

swelling at the inner angle of the eye.
Ca'se-in (Lat. caseus, cheese). A proteid substance found especially in

milk. The principal ingredient in cheese.
Ca-tarrh'. Inflammation of a mucous membrane.

34° Life and Health

Cau'da e-qui'na (Lat., horse's tail). The collection of large nerves
descending from the lower end of the spinal cord.

Cell (Lat. cclla, a storeroom). One of the ultimate units of which all living
bodies are composed. A granular mass of protoplasm containing a nucleus.

Cer'e-berium (Lat. dim. of cerebrum* the brain). The part of the brain
lying below the cerebrum and above the pons and medulla oblongata.

Cer'e-brum. The brain proper, occupying the upper portion of the skull.

Ce-ni'mi-nous (Lat. cerumen, ear wax). Pertaining to cerumen, or ear wax.

Chlo'ral. A powerful drug and narcotic poison used to produce sleep.

Chlo'ro-form. A narcotic poison generally used by inhalation ; of extensive
use in surgical operations to produce anaesthesia.

Chon'drin (Gr. x6v5/x>s, cartilage). A kind of albuminoid resembling gela-
tine obtained by boiling cartilage.

Chor'dae ten-di'ne-ae. Tendinous cords,. connecting the papillary muscles
of the heart with the auriculo-ventricular valves.

Cho'roid (Gr. ykpiov, skin, and efSos, form). The middle coat of the eyeball.

Cil'i-a (Lat. pi. of cilium, an eyelash). Minute thread-like processes found
upon the cells of the air passages and other parts.

Cil'ia-ry mus'cle. A small muscle of the eye which assists in accom-
modation.

Cir'cum-val'late (Lat. circum, around, and vallum, a rampart). The name
given to certain papillae of the tongue.

Co-ag'u-la'tion (Lat. coagular'e, to curdle). The process by which a liquid
like blood or milk clots, or solidifies.

Co'ca-ine. A bitter, white substance obtained from the leaves of coca,
capable of producing local insensibility to pain when applied to the
surface of mucous membranes or injected under the skin.

Coch'le-a (Lat. cochlea, a snail shell). The spiral cavity of the internal ear.

Co-lum'nae car'ne-ae. Fleshy projections in the ventricles of the heart.

Co 'ma (Gr. KW/LUI, lethargy). A deep stupor from which it is difficult or
impossible to arouse a person.

Com'mis-sure (Lat. con, together, and mittere, to put). A bridge-like
structure uniting similar parts.

Com'press. A pad or bandage applied directly to an injury.

Con'cha (Gr. xoyx^ * mussel shell). The shell-shaped portion of the
external ear.

Con-ges'tion (Lat. con, together, and gcrere, to bring). Abnormal collec-
tion of blood in a part or organ.

Con'junc-ti'va (Lat. con, together, and jurtgere, to join). A thin layer of
mucous membrane which lines the eyelids and covers the front of the
eyeball, thus joining the latter to the lids.

Glossary 341

Con-sump 'tion (Lat. consumer?, to consume). A wasting disease like tuber-
culosis, especially pulmonary tuberculosis.

Con-ta'gion (Lat. con, with, and tangere, to touch). The process by
which a specific disease is communicated from one person to another,
either by contact or by means of an intermediate agent. Also the
specific germ, or virus, which causes a communicable disease.

Con'trac-til'i-ty (Lat. con, together, and trahere, to draw). The property
of a muscle which enables it to draw its extremities closer together.

Con/vo-lu/tions (Lat. con, together, and volvcre, to roll). Tortuous fold-
ings, as those of the external surface of the brain.

Co-or'di-na'tion. The manner in which several different organs of the
body are brought into such relations with one another that their func-
tions are performed in harmony.

Cor'a-coid (Gr. /c6/m£, a crow, elSos, form). Shaped like a crow's beak.

Cor'ne-a (Lat. cornu, a horn). The transparent horn-like substance which
covers a part of the front of the eyeball.

Cor'o-na-ry (Lat. corona, a crown). A term applied to vessels and nerves
which encircle a part or organ, as the coronary arteries of the heart.

Cor'o-noid (Gr. nop&vt), a crow). Like a crow's beak; thus the coronoid
process of the ulna.

Cri'coid (Gr. /cpkoj, a ring, and cTSos, form). A cartilage of the larynx
resembling a seal ring in shape.

Crys'tal-line lens (Lat. crystallum, a crystal). One of the refractive media
of the eye ; a double-convex body situated in the front part of the eyeball.

Cu/mu-la-tive. The action from drugs which supervenes after the taking
of several doses with little or no effect.

Cu'ti-cle (Lat. dim. of cutis, the skin). Scarf skin ; the epidermis.

Cu'tis (Gr. ffKvros, a skin, or hide). The true skin, also called the dermis.

De-gen'er-a'tion (Lat. degenerare, to grow worse, to deteriorate). A morbid

process in the structure of an organ by which its tissues are converted

into some inert substance.

Deglu-ti'tion (Lat. deglutirc, to swallow). The act of swallowing.
Den'tine (Lat. dens, dcntis, a tooth). The hard substance which forms the

greater part of a tooth ; ivory.
De-o'dor-ant (Lat. de, without, and odorare, to smell). A substance which

removes or conceals offensive odors.
Dex'trin (Lat. dexter, right). A soluble carbohydrate into which starch is

converted by diastase or dilute acids or by dry heat.
Dex trose' (Lat. dexter, right). Grape sugar.
Di-as'to-le (Gr. Siao-rAXetv, to dilate). The relaxation of the heart.

342 Life and Health

Dip'lo-C (Gr. SiTrXoiJ, a fold). The spongy, osseous tissue between the dense
outer and inner tables of the skull.

Dip'so-ma'ni-a (Gr. Stya, thirst, and pavta, madness). The uncontrollable
desire for spirituous liquors.

Dis'in-fec'tants. Agents used to destroy the germs of disease, fermenta-
tion, and putrefaction.

Dis'lo-ca'tion (Lat. dislocare, to put out of place). An injury to a joint
in which the bones are displaced or forced out of their sockets.

Dis-sec'tion (Lat. dis, apart, and secare, to cut). The cutting up of an
animal in order to learn its structure.

Du'o-de'num (Lat. duodcni, twelve). The first division of the small intes-
tines, about twelve fingers' breadth long.

Dys-pep'si-a (Gr. Stfi-, ill, and irtirTeiv, to digest). Disturbed digestion.

Dysp-nce'a (Gr. 5«Js-, difficult, and irvteiv, to breathe). Difficult breathing.

Effer-ent (Lat. efferre, to carry out). Bearing or carrying outwards, as

from the center to the periphery.
Ef-flu'vi-a (Lat. efflutre, to flow out). Offensive odors coming from the

body, and from decaying animal or vegetable substances.
Ere-ment (Lat. elemcntum). One of the simplest parts of which anything

consists.
E-lim'i-na'tion (Lat. f, out of, and limen, liminis, a threshold). The act

of expelling waste matters. Signifies literally " to throw out of doors."
E-met'ic (Gr. ^/iert*c6s, causing vomiting). An agent which causes vomiting.
E-mul'sion (Lat. emulgere, to milk). A preparation consisting of a liquid,

usually water, containing an insoluble substance, as fat, in suspension.
E-nam'el (Fr. email}. Dense material covering the crown of a tooth.
En'do-lymph (Gr. ev5ov, within, and Lat. lympha, water). The fluid in the

membranous labyrinth of the ear.

En'dos-mo'sis (Gr. evdov, within, and oJ^6s, pushing). The current from with-
out inwards when diffusion of fluids takes place through a membrane. .
En'do-the'li-um (Gr. cvSov, within, and #17X77, nipple). The thin epithelium

lining the blood vessels, lymphatics, and serous cavities. •
En'zyme (Gr. tv, in, f>5/xr7, leaven). Any ferment formed within the living

organism. A chemical ferment, as distinguished from organized fer-
ments, such as the yeasts. See Ferment.
Ep'i-dem'ic (Gr. tirt, upon, and STJ/JLOS, the people). A disease which affects

large numbers, or which spreads over a wide area.
Ep'i-glot'tis (Gr. tirl, upon, and 7X0)7-1-15, the entrance to the windpipe). A

leaf-shaped lid which covers the top of the larynx during the act of

swallowing.

Glossary 343

Ep'i-lep'sy (Gr. eirlXvi^is, a seizure). A nervous affection accompanied by

fits and sudden loss of consciousness.
E'ther (Gr. ai&rip, the pure, upper air). A narcotic poison. Its chief use

is as an anaesthetic in surgical operations.
Eu-sta'chi-an tube (from an Italian anatomist named Eustachio). The

tube which leads from the throat to the middle ear.
Ex-cre'ta (Lat. excernere, to separate). The refuse matter which is passed

from the body in any form.
Ex-cre'tion (Lat. excernere, to separate). The separation from the blood

of the waste matters of the body ; also the materials excreted.
Ex'os-mo'sis (Gr. e£w, without, and u>6teiv, to push). The current from

within outwards when diffusion of fluids takes place through a

membrane.
Ex-ten'sion (Lat. ex, out, and tender e, to stretch). The act of restoring

a limb, etc., to its natural position after it has been flexed or bent;

the opposite of flexion.

Fau'ces (Lat. fauces). The part of the mouth which opens into the pharynx.

Fe-nes'tra (Lat.). Literally, "a window." Fenestra ovalis and fenestra
rotunda, the oval and the round window; two apertures in the bone
between the tympanic cavity and the labyrinth of the ear.

Fer/ment (Lat. fermentum). Any substance which in contact with another
substance is capable of setting up changes (fermentation) in the latter,
without itself undergoing much change. Ferments are classified into
unorganized, or soluble, and organized, or living, ferments. See
Enzyme.

Fer/men-ta'tion (Lat. fermentum, boiling). The process of undergoing an
effervescent change, as by the action of yeast; in a wider sense, the
change of organized substances into new compounds by the action of
a ferment. It differs in kind according to the nature of the ferment.

Fi-brilla (Lat.). A little fiber; one of the longitudinal threads into
which a striped muscular fiber can be divided.

Fi'brin (Lat. fibra, a fiber). A proteid substance contained in the flesh of
animals, and also produced by the coagulation of blood.

Fol'li-cle (Lat. dim. otfollis, a money bag). A little pouch or depression, as
the hair follicle.

Fo'men-ta'tion (Lz.t.fomentare, to keep warm). The application of heat
and moisture to a part to relieve pain or reduce inflammation.

Fo-ra'men (Lat. forare, to pierce). A hole, or an aperture.

Fron'tal si'nus. A blind or closed cavity in the bones 3f the skull just
over the eyebrows.

344 Life and Health

Fu'mi-ga'tion (Lat. fumigare, to smoke). Disinfection by means of a

vapor.
Func'tion (L&t.funcfw, a doing). The normal or special action of a part.

Gan'gli-on (Gr. ydyy\iov, a knot). A collection of nerve cells.

Gel'a-tine (Lat. gdarc, to congeal). An albuminoid substance which dis-
solves in hot water and forms a jelly on cooling.

Germ (Lat. germen, a sprout, bud). A portion of matter capable of devel-
oping into a living organism, — a micro-organism.

Ger'mi-cide (germ, and Lat. caedere, to kill). An agent which destroys
germs, especially bacteria.

Gland (Lat. glans, an acorn). An organ consisting of one or more follicles
and ducts, with numerous blood vessels interwoven.

Glot'tis (Gr. y\uTTa, the tongue). The space between the vocal cords.

Glu'cose'. A kind of sugar found in fruits, also known as grape sugar.

Gly'co-gen (Gr. y\vi<fa, sweet, and yevfa, producing). A substance
belonging to the carbohydrates, found especially in the liver; also
known as animal starch.

Gust'a-to-ry (Lat. gustare, to taste). Belonging to the sense of taste.

Haem'o-glo'bin (Gr. of/ia, blood, and Lat. globus, a globe or globule). A
complex proteid substance which forms the principal coloring con-
stituent of the red corpuscles of the blood.

Hem'i-sphere (Gr. ^-, half, and <r0cupa, a sphere). Half a sphere, the
lateral halves of the cerebrum, or brain proper.

Hem'or-rhage (Gr. afca, blood, and p-fiyvvfu, to burst). Bleeding, or the
loss of blood.

He-pat'ic (Gr. fjirap, the liver). Pertaining to the liver.

He-red'i-ty (Lat. hereditas, heirship). The predisposition or tendency
derived from one's ancestors to definite physiological actions or ana-
tomical peculiarities.

Hilum, sometimes written hilus. A small fissure, notch, or depression,
a term applied to the concave part of the kidney.

Ho'mo-ge'ne-ous (Gr. 6/*6s, the same, and ytvos, kind).. Of the same kind or
quality throughout; uniform in nature, — the reverse of heterogeneous.

Hu'mor. The transparent contents of the eyeball.

Hy'a-line (Gr. vaXos, glass). Glass-like, resembling glass in transparency.

Hy'dro-gen. An elementary gaseous substance, which, in combination
with oxygen, produces water.

Hy/dro-pho'bi-a (Gr. v8wp, water, and <f>optofjuti, to fear). A disease caused
by the bite of a rabid dog or other animal.

- .Glossary 345

Hy/per-me-tro/pi-a (Gr. virfy, over, ptrpov, measure, and w^, the eye).

Farsightedness.
Hy-per'tro-phy (Gr. inrtp, over, and rpo^, nourishment). Excessive

growth ; thickening or enlargement of any part or organ.

Im-mune' (Lat. immunis, free or exempt). Exempt from certain diseases

by inoculation, by previous attack, or by nature.
In-ci'sor (Lat. incaedere, to cut into). Applied to the four front teeth of

both jaws, which have sharp, cutting edges.

In'cus. An anvil ; the name of one of the bones of the middle ear.
In'di-an hemp. The common name of Cannabis Indica, an intoxicating

drug known as hasheesh and by other names in Eastern countries.
In-fec'tion (Lat. in, in, and facere, to make). The communication of

disease from one body to another, or from one part to another part of

the same individual (auto-infection). The material conveying the

disease ; the disease-producing agent.
In-fe'ri-or ve'na ca'va. The vein carrying blood from the lower part of

the body into the heart.
In'flam-ma'tion (Lat. in, in, and flammare, to flame). Tissue changes

accompanied with redness or swelling of any part of the body, with heat

and pain.
In-oc'u-la'tion (Lat. inoculare, to ingraft). The introduction of the

germs of disease, generally through the skin, so as to produce the

disease.
In-sari-va/tion (Lat. in, in, and saliva, spittle). The mingling of the saliva

with the food during the act of chewing.
I'ris (Lat. iris, the rainbow). The thin muscular ring which lies between

the cornea and crystalline lens, giving the eye its special color.

Jaun'dice (Fr. jaunisse, yellow). A disorder in which the skin, eyes,
mucous membranes, and secretions assume a yellowish tint, due to the
presence of bile pigments in the blood.

Ka-tab'o-lism (Gr. Kara^d\\eiv, to throw down). The process by means of
which the more complex substances are rendered more simple and less
complex. The opposite of anabolism.

Lab'y-rinth (Gr. Xa^pi^os, a maze). The internal ear, so named from its

many windings.
Lach'ry-mal, or lacrymal apparatus (Lat. lacrima, a tear). The organs

for forming and carrying away the tears.

346 Life and Health

La-ryn'go-scope (Gr. \dpvy£, larynx, and tr/coTretV, to behold). An instru-
ment consisting of a small mirror which may be held in the throat, and
a reflector to throw light on it, by which the interior of the larynx is
brought into view.

Lens (Lat., a'lentil). A piece of transparent glass or other substance so
shaped as either to converge or disperse the rays of light.

Lig'a-ture (Lat. ligarc, to bind). A thread of some material used in tying
arteries or other parts.

Lymph (Lat. lympha, pure water). The watery fluid in the lymphatic vessels.

MaHe-us (Lat. malleus, a hammer). The mallet; one of the small bones
of the middle ear.

Me-a'tus (Lat. meare, to pass). A natural passage or canal.

Me-dul'la ob-lon-ga'ta. The "oblong marrow," also called the spinal
bulb ; that portion of the brain which lies upon the basilar process of
the occipital bone.

Mei-bo'mi-an. A term applied to the small glands between the conjunc-
tiva and tarsal cartilages, discovered by Meibomius.

Mem-bra'na tym'pa-ni. Literally, " the drum membrane"; the membrane
separating the outer from the middle ear.

Mes'en-ter-y (Gr. /^<ros, middle, and evrepov, the intestine). A fold of the
peritoneum, surrounding an intestine, especially the small intestine.

Me-tab'o-lism. (Gr. /iera/SoXTj, change). The changes taking place in cells,
whereby they become more complex and contain more force, or less
complex and contain less force. The former is constructive metabolism,
or anabolism ; the latter, destructive metabolism, or katabolism.

Mi'crobe (Gr. /xt/cp6s, little, and £fos, life). A living organism of very small
size — a micro-organism — either animal or vegetable.

More-cule (Lat. dim. of moles, a mass). The smallest portion of a sub-
stance which can retain the properties of the substance.

Mor-phol'o-gy (Gr. /iop0^, form, and X67os, discourse). The science that
treats of form or structure of organized beings.

Mo'tor (Lat. movere, to move). The name of the nerves which conduct
to the muscles the stimulus which causes them to contract.

Mu'cous mem'brane. The thin layer of tissue which covers those internal
cavities or passages which communicate with the external air.

Mu'cus. The thin glaify fluid secreted by mucous membranes.

My-o'pia (Gr. friciv, to shut, and aty, the eye). A defect of vision dependent
upon too great length of the eyeball, rendering distant objects indistinct ;
nearsightedness.

My'o-sin (Gr. /xus, muscle). Chief proteid substance of muscle.

Glossary 347

Nar-COt'ic (Gr. vapicdeiv, to benumb). A substance that produces stupor,
convulsions, and sometimes death.

Nic'0-tine. The poisonous alkaloid found in the leaves of the tobacco
plant.

Nu-cle'o-lus (Lat. dim. of nucleus). A small body often found within the
nucleus of a cell.

Nu'cle-us (Lat. nucleus, kernel). An essential part of a typical cell, often
spherical and usually found near the center.

Nu-tri'tion (Lat. nutrire, to nourish). The processes by which the nourish-
ment of the body is accomplished.

0-don'toid (Gr. odofa, a tooth, and eiSos, shape). The name of the bony peg

of the second vertebra, around which the first turns.
(E-soph'a-gus (Gr. <ptpeiv, ofoeiv, to carry, and <j>ayeii>, to eat). The tube

leading from the throat to the stomach ; the gullet.
0-lec'ra-non (Gr. uXtvrj, the elbow, and Kpaviov, the top of the head). A

curved eminence at the upper and back part of the ulna.
Os-mo'sis (Gr. 0)07*65, impulsion). Diffusion of liquids through membranes.
Os'sa in-nom-i-na/ta, pi. of os innominatum (Lat.). The irregular or

" unnamed " bones of the pelvis, so called on account of their non-
resemblance to any known object.
O'to-co'ni-a (Gr. ofo, an ear, and Kovia, dust). Minute crystals of lime in

the vestibule of the ear; also known as otoliths.
Ox-i-da'tion (Gr. 6£us, sharp). The union of oxygen with other substances,

as in combustion. The essential part of burning and of breathing.

Pa-cin'i-an cor/pus-cles (Pacini, an Italian physician). One of the forms

of end organs for the sense of touch.
Pal'ate (Lat. palatum, the palate). The roof of the mouth, forming the hard

palate, and the curtain at the back of the mouth, called the soft palate.
Pal'pi-ta'tion (Lat. palpitatio, a frequent or throbbing motion). A violent

and irregular beating of the heart.
Pa-pilTae (Lat., a nipple). The small elevations found on the skin and

mucous membranes.
Pa-rary-sis (Gr. irapaXfaiv, to loosen; also, to disable). Loss of function,

especially of motion or feeling.
Par'a-site (Gr. ra/od, near, and <T?TOS, food). A plant or animal living upon

or within another organism, called the host.

Pervis. Literally, " a basin " ; the bony cavity at the lower part of the trunk.
Pep'sin (Gr. Trtirretv, to cook). A ferment found in the gastric juice, and

capable of digesting proteids in the presence of an acid.

348 Life and Health

Pep'tone (Gr. TT^TTTCIJ', to cook). A proteid body formed by the action of
ferments on albumins or other proteids during gastric and pancreatic
digestion.

Per/i-car/di-um (Gr. ire/>£, about, and Kapdla, heart). The sac enclosing the
heart.

Pert-os'te-um (Gr. ircpL, around, and do-rtov, a bone). A delicate membrane,
which invests and nourishes the bones.

Pert-startle move'ments, or peristalsis (Gr. irepl, round, and a-i-AXeii;, to
send). The slow, wave-like movements of the stomach and intestines.

Pert-to-ne'um (Gr. irepirriveiv, to stretch around). The investing mem-
brane of the stomach, intestines, and other abdominal organs.

Pha-lan'ges (Gr. <j>d\ay£, a body of soldiers closely arranged in ranks and
files). The bones of the fingers and toes.

Pharynx (Gr. 4>dpvy£, the throat). The cavity behind the mouth and the
nose, leading to the gullet.

Pi'a ma'ter (Lat.). Literally, "the tender mother"; the innermost of the
three coverings of the brain. It is thin and delicate; hence the name.

Pin'na (Lat., a feather or wing). External cartilaginous flap of the ear.

Plas'ma (Gr. TrXatro-etv, to mould). The fluid part of the blood and
the lymph.

Pleu'ra (Gr. TrXevpd, the side, also a rib). A membrane covering the lung
and lining the chest.

Plex'us (Lat. plectere, to braid). A network of vessels, nerves, or fibers.

Pneu'mo-gas'tric (Gr. irve^uv, the lungs, and yaffrrfp, the stomach). The
longest of the cranial nerves giving off branches to the lungs, the heart,
the alimentary canal, and other parts ; also called the vagus, or wander-
ing nerve.

Poi'son (Fr., from Lat. potio, a draught). A substance that when introduced
into the body either destroys life or impairs seriously the function of
one or more of its organs.

Pons Va-roli-i (Lat. pans, a bridge, and Varolius). The white fibers which
form a bridge connecting the different parts of the brain, first described
by Varolius.

Pop-li-te'al (Lat. poples, poplitis, the ham, the back part of the knee). The
space behind the knee joint is called the popliteal space.

Portal vein (Lat. porta, a gate). The venous trunk formed by the veins
coming from the stomach and the intestines. It carries the blood
to the liver.

Pres'by-o'pi-a (Gr. irptrpvs, old, and oty, the eye). A defect of the accom-
modation of the eye, caused by the hardening of the crystalline lens;
the farsightedness of adults and aged persons.

Glossary 349

Proc'ess (Lat. procedere, processus, to proceed, to go forth). Any projection

from a surface ; also, a method of performance, a procedure.
Pro-nation (Lat. pronus, inclined forwards). The turning of the hand with

the palm downwards.

Pro-na'tor. A muscle which turns the hand palm downwards.
Pro'te-ids (Gr. TrpcDros, first, and e!5os, form). A general term for the

albuminous constituents of the body.
Pro'to-plasm (Gr. irpuros, first, and TrXdoro'eij', to mould). The viscid

material constituting the essential substance of living cells, upon which

all the vital functions of the body depend.

Pter'y-goid (Gr. irrfyvi-, a wing, and efSos, form, resemblance). Wing-like.
Pto'ma-ine (Gr. TTTW^O, a dead body). One of a class of substances,

resembling the vegetable alkaloids, formed during the decomposition of

proteid. See Toxin.
Pty'a-lin (Gr. Trrfaiv, to spit). A ferment in saliva, having power to con-

vert starch into sugar.
Pu'pil (Lat. pupilla). The central, round opening in the iris, through which

light passes into the interior of the eye.
Pus (Gr. TTUOS, foul). A yellowish white, creamy liquid produced by the

process of suppuration. It consists mostly of cells floating in a liquid.
Py-ae'mi-a (Gr. irtov, pus, and al/m, blood). A form of blood poisoning

produced by the absorption into the blood of morbid matters usually

originating in a wound or local inflammation.
Py-lo'rus (Gr. irv\ovpfa, a gate keeper). The opening of the stomach at

the beginning of the small intestine.

Re'flex (Lat. reflexus, turned back). Involuntary movements or secretion
produced by an excitation traveling along a sensory nerve to a center,
where it is turned back or reflected along motor or secretory nerves.

Res'pi-ra'tion (Lat. rcspirare, to breathe). The act of breathing in and
breathing out air.

Ret'i-na (Lat. retc, a net). The innermost of the three tunics, or coats, of
the eyeball, being an expansion of the optic nerve.

Ri'ma glot'ti-dis (Lat. rima, a chink or cleft). The opening of the
glottis.

Roent'gen-rays, see X-rays.

Sar'co-lem'ma (Gr. <r<£/>£, flesh, and X^ujwa, a husk). The membrane which
surrounds the contractile substance of a striped muscular fiber.

Scle-rot'ic (Gr. o-fcXijpis, hard). The tough fibrous outer coat of the
eyeball.

350 Life and Health

Scur'vy. A disease caused by use of improper food for a length of time,

having prominent skin symptoms.

Se-ba'ceous (Lat. sebum, fat). Resembling fat ; the name of the oily secre-
tion by which the skin is kept flexible and soft.

Se-cre'tion (Lat. seccrnere, secretum, to separate). The process of separat-
ing from the blood some essential, important fluid, which fluid is also

called a secretion.

Sem'i-cir'cu-lar ca-nals'. Three canals in the internal ear.
Sep'ti-cae'mi-a (Gr. o-rjTrTiK6s, putrid, and afyta, blood). Blood poisoning,

a form of poisoning resulting from the presence in the blood of the

products of putrefactive micro-organisms.
Se'rum (Lat.). The clear, watery fluid which separates from the clot of the

blood.
Spu'tum, pi. sputa (Lat. spuere, sputum, to spit). Matter which is coughed

up from the air passages.
Sta'pes (Lat.). Literally, "a stirrup"; one of the small bones of the

middle ear.
Ster'il-ize (Lat. sterilis, without power to produce seed). The destruction

of micro-organisms, especially by heat. Commonly applied to the

preparation of milk for infants and to surgical dressings.
Stim'u-lant (Lat. stimulare, to prick or goad on). An agent which causes

an increase of activity in the body or in 'any of its parts without

increasing its supply of energy.
Styp'tics (Gr. O-TVTTTI^J, astringent). Substances that applied locally arrest

bleeding.
Sub-cla'vi-an vein (Lat. sub, under, and clavis, a key). A great vein, so

called because it is situated underneath the clavicle, or collar bone.
Su-pe'ri-or ve'na ca'va (Lat., upper hollow vein). The great vein of the

upper part of the body.
Syn-o'vi-a (Gr. aiiv, with, and u6v, an egg). The fluid secreted by the

synovial membranes, which lubricates the joints ; joint oil. It resembles

the white of a raw egg.
Sys'to-le (Gr. o-uo-rAXeiv, to contract). The contraction of the heart, by

which the blood is expelled from that organ.

Tem'po-ral (Lat. tempus, time, and tempora, the temples). Pertaining to
the temples ; so called because the hair begins to turn white with age
in that portion of the scalp.

Tet'a-nus (Gr. relveiv, to stretch). A disease marked by persistent contrac-
tions of all or some of the voluntary muscles ; those of the jaw are
sometimes solely affected ; it is then termed lockjaw.

Glossary 351

Thy'roid (Gr. Ovptos, a shield, and eUos, form). The largest of the carti-
lages of the larynx; its projection in front is called Adam's apple.

Tis'sue (Fr. tissu, from Lat. texere, to weave). Any substance or texture
in the body formed of various elements, such as cells, fibers, blood ves-
sels, etc., interwoven with each other.

To-bac'co (Indian tabaco, the tube, or pipe, in which the Indians smoked
the plant). A narcotic plant used for smoking and chewing, and in snuff.

Toxin (Gr. rogucl?, poison). A poison formed by bacteria, in both living
tissues and dead substances ; a poisonous ptomaine.

Tra'gus (Gr. rpdyos, a goat). The eminence in front of the opening of the
ear; sometimes hairy, like a goat's beard.

Tro-chan'ter (Gr. rpoxcieii/, to turn, to revolve). Name given to two pro-
jections on the upper extremities of the femur.

Tryp'sin (Gr. rptyis, a rubbing). The ferment principle in pancreatic juice
which converts proteid material into peptones.

Tu'ber-cle (Lat. tuberculum, a little lump). A pimple, swelling, or tumor ;
the specific lesion produced by the tubercle bacillus.

Tu-ber'cu-lo'sis (same derivation as tubercle). An infectious disease
due to the bacillus tuberculosis discovered by Koch. The form of
this disease with marked pulmonary symptoms is popularly known as
consumption.

Tu'ber-os'i-ty (Lat. tuber, tuberis, a swelling, a protuberance).

Tur'bi-na'ted (Lat. turbinatus, from turbo, turbinis, a top). Formed like
a top ; a name given to the bones in the outer walls of the nasal fossae.

Tym'pa-num (Gr. r^^iravov, a drum). The cavity of the middle ear, resem-
bling a drum in being closed by two membranes.

U're-a (Gr. otpov, urine). Chief solid constituent of urine ; nitrogenous

product of tissue decomposition.
U-re'ter (Gr. ovprjr^p, a tube for the urine). The tube through which the

urine is conveyed from the kidneys to the bladder.
U'vu-la (Lat. uva, a grape). The small pendulous body at the middle of

the soft palate.

Vac'cine vi'rus (Lat. vacca, a cow, and virus, poison). The virus used in

performing vaccination, now usually derived directly from heifers affected

with cowpox.
Varvu-lae con-ni-ven'tes (Lat. valvula, a small valve, and connivens, to

bring close together). A name given to transverse folds of the mucous

membrane in the small intestine.
Var'i-cose (Lat. varix, a dilated vein). Distended or enlarged, as a vein.

352 Life and Health

Vas'cu-lar (Lat. vasculum, a little vessel). Pertaining to or possessing
blood or lymph vessels.

Va/sO-mo/tor (Lat. vas, a vessel, and movere, motum, to move). Causing
motion to the vessels. Vasomotor nerves cause contraction and relaxa-
tion of the blood vessels.

Ve'nae ca'vse, pi. of vena cava. Literally, " hollow veins " ; a name given
to the two great veins which meet at the right auricle of the heart.

Ven'ti-la'tion (Lat. ventilare, to fan). The process of replacing the foul or
vitiated air in any room or confined space with air that is pure.

Ver'mi-form (Lat. vcrmis, a worm, and forma, form). Worm-shaped.

Ves'ti-bule (Lat. vestibulum, a porch). A portion of the internal ear, com-
municating with the semicircular canals and the cochlea.

Villi (Lat. villus, shaggy hair). Minute thread-like projections upon the
internal surface of the small intestine.

Vi'rus (Lat., poison). The poison of an infectious disease, especially one
found in the secretions or tissues of an individual or animal suffering
from an infectious disease.

Vi'tal knot. Common name for that part of the medulla oblongata the
destruction of which causes instant death ; the respiratory center.

Vit're-ous (Lat. vitrum, glass). Having the appearance of glass ; applied
to the humor occupying the largest part of the cavity of the eyeball.

Viv/i-sec/tion (Lat. vivus, alive, and secare, to cut). Dissection of a living
animal ; experimentation upon an animal while still alive.

Vo'cal cords. Two elastic bands or transverse folds of the larynx.

X-rays, or Roentgen-rays. The peculiar ether rays or waves discovered
by Roentgen in 1895. These rays penetrate substances like wood, the
bodily tissues, and many other substances which are opaque to the light
of the sun ; extensively used in the diagnosis of surgical cases.

Zy-go'ma (Gr. $vy6i>, a yoke). The arch formed by the malar bone and
the zygomatic process of the temporal bone.

INDEX

Absorption

by mouth and stomach .

by the intestines . . .
Accidents and emergencies .
Achilles, Tendon of ....
Air, made impure by breathing

Necessity of pure . . .

Foul, effect of, on health
Alcohol, Effect of, on bones .

Effect of, on muscular wo rk

Effect of, on capacity for
physical exercise .

Properties of

Effects of small quantities
of

not a food

as a poison

Effect of, on gastric diges-
tion

Effects of, on the liver

Effect of, on the blood .

Effect of ,on the circulation

Effect of, on the heart .

Effect of, on respiration .

Effect of, on pulmonary
diseases

Effect of, on kidneys . .

and the brain . ....

Effect of habitual use of,
upon brain

Self-control weakened by

Evil results of, inherited .

1 20
120
121
302
56

76
46
62

77
90

93
94
95

156

1S7
158
181

182
205
230

232
232
233

PAGES

Alcohol, Effect of, on taste . 245

Effect of, on vision . . 263
Effect of, on throat and

voice . . 284

Alcoholic beverages . . . . 90, 93

fermentation 91

fermentation and bacteria 293

Anabolism defined .... 5

Anatomy defined 6

Antidotes for poisons . . . 315

Antitoxin treatment of disease 291

Aorta and its branches . . . 145

Apparatus, Question of . . . 318

Appendicitis 112

Arteries 145

Arytenoid cartilages .... 278

Asphyxia ....... 311

Astigmatism 256

Atmosphere, how made impure 174

Auditory canal 265

Backbone 31

Bacteria, Nature of .... 286

Action of 287

Disease-producing . . . 288

Place of, in nature ... 288
Disease-producing, in

foods 289

Disease-producing, in soil 289

Access of, to body . . . 290

Diseases caused by ... 290

Defense of body against . 291

353

354

Life and Health

Bacteria, Behavior of, within
body

Behavior of, within
wounds 292

and alcoholic fermentation
Bathing, Hints on ....

Salt-water

Baths, and bathing ....

Hot

Cold

Beverages, Fermented . . .

Bicycle, Use of 76

Bile

Biology defined . . .

Bladder 204

Bleeding, from nose . .

How to stop . . . 304
Blood, corpuscles ... 136,

Physical properties of . .

Coagulation of ....

Apparatus for circulation
of

Effect of respiration upon

Gases of 171

Blood vessels, Nervous control
of

Effect of alcohol on . .

connected with heart 143,

Injuries to 303

Bodies, living, Main features of

our, Facts concerning . .
Bone, Chemical composition of

Physical properties of . .

Microscopic structure of .

Self -formative power of .
Bones, uses of, The ....

Growth of, how modified .

Broken 45, 309

broken, Treatment for

Effect of alcohol on .

PAGES
292

292

293
197
198

'95
196
196
92
76
"3
5
204
306
• 3°5
» i37
136
i37

i39
171
171

'52

J57
» M4
303
3

2
21
22

25
26

43
44
.309
46
46

Bones, Effect of tobacco on .
Table of

PAGES

47
48

210
21 I
212
2I4
222
D-232

I63
306

M7
9
37
J9
19
*9
T9
277
^78

Brain, as a whole
Weight of

Under surface of . . .
Membranes of . . . .
Reflex center in . . . .
Effects of alcohol on . 23
Bronchial tubes ....

Burns or scalds
Capillaries

Carbohydrates

Carpus
Cartilage

Hyaline

White fibro- . . . .

Yellow fibro-

Thyroid
Arytenoid .

278
10
ii
ii

12
13

'5

207

212

213
21 I
212

7
1 68

234

274

Cells
and the human organism
Differentiation of ...
Kinds of

Vital properties of ...
Epithelial

Nerve .... .

Cerebellum

Functions of

Cerebrum

Convolutions of . . . .
Chemical elements in the body
Chest, as air-tight chamber .
Chloral

Choroid coat

250
1 2O
109
I64

Chyle .

Chyme
Cilia of air passages ....

Index

355

PAGES

Ciliary muscle 252

Circulation, Portal .... 149

Pulmonary 147

Systemic 148

Effect of alcohol on . . 1 57

Clavicle 35

Cleanliness, Necessity for . . 195

Clothing, Use of 199

Precautions in use of . . 199

Suggestions for use of . 199

Effects of tight-fitting . . 200

catching fire 307

Coagulation of blood . . . 137

Cocaine 235

Coccyx 32

Cochlea 268

Coffee 89

Colon 112

Color-blindness 260

Condiments 87

Conjunctiva 258

Connective tissues .... 16

with elastic fibers ... 17

with white fibers ... 17

Consumption .... 297, 317

Contraction, Object of ... 54

Contusions and bruises . . 302

Cooking 89

Coughing 174

Cornea 249

Corpuscles, Blood .... 136

Red 136

White 137

Cranial nerves 217

Cranium, Bones of .... 27

Cricoid cartilage 278

Crying 174

Crystalline lens 252

Cuticle 187

Cutis vera, or true skin . . . 186

PAGES

Deglutition 104

Diaphragm 165

Diet, Important articles of . 83

Too generous .... 127

Digestion, Organs of ... 98

in small intestines . . . 1 18

in large intestines . . . 120
Effect of alcohol on . 132, 133

Diphtheria 298

Disease, Means to avert dan-
ger from 295

Diseases, infectious and con-
tagious, Management of 297
Hints on nursing . . . 301
Disinfectants, Air and water as 296

Common 296

Disinfection ". 296

Dislocations 45

Distilled liquors 93

Drowning, Apparent . . . . 311

Method of treating . . . 312

Duct, Hepatic 114

Common bile 114

Cystic 114

Thoracic 123

Nasal 259

Duodenum 109

Ear, External 264

Middle 265

Bones of the 266

Internal 267

Practical hints on care of 271

Suggestions on care of . 272

Foreign bodies in . ', . 308

Eating, Practical points about 129

Eggs as food 83

Elements, Chemical, in the

body 7

Endothelium 15

356

Life and Health

PACES I

Energy, Potential 5

Kinetic 5

Epidermis, or cuticle . . . 187

Epiglottis 104, 162

Epithelium 14

Ciliated 15

Columnar 15

Glandular 15

Squamous 15

Ether 234

Ethmoid bone 28

Eustachian tube 266

Excretion 184

Exercise, Physical .... 66
Importance of .... 66
Muscularcoordinationand 67
Effect of, on bodily tem-
perature 68

Effect of, on circulation

and digestion .... 68
Effect of, on digestion . 68
Effect of, on personal ap-
pearance 69

Effect of excessive . . 69, 70

Amount of, required . . 73

Time for 74

Physical, in school ... 76
Effect of alcohol and to-
bacco on capacity for . 77
Practical points about . 77
Experimental work in physi-
ology 317

Importance of . . . . 317

Expiration 167

Epre 247

Inner structure of ... 251

Refractive media of . . 253

Movements of .... 257

Hints on care of ... 262

Hints on using .... 262

PAGES

Eye, how abused 262

Effect of tobacco and

alcohol on 263

Foreign bodies in ... 309

Eyeball 248

Coats of 248

Eyelashes and eyebrows . . 258

Eyelids 258

Face 28

Bones of the 29

Fainting 310

Fats 9

and oils 81

Femur 39

Fermentation, Alcoholic . . 91

Nature of 91

Fibula 39

Fish as food 84

Fits, Epileptic and hysterical . 310

Food, Necessity for .... 79
Waste made good by . 79, 98
Quantity of, as affected

by circumstances. . . 126
Quantity of, as affected

by occupation . . . 127

Need of variety of . . . 128

Foods, Classification of . . 80

Nitrogenous 80

Proteid 80

Fatty 81

Starch and sugar ... Si

Saline 82

Proteid vegetable ... 84

Vegetable 84

Non-proteid animal . . 85

Non-proteid vegetable . 85

Table of 130

Food materials, Table of . . 86

Foot 40

Index

357

Foramen magnum .... 27

Forearm 36

Fractures, Different kinds of . 45

Framework, Body .... 21

Frontal bone 27

Frost bites 307

Fruits as food 87

Gallbladder 114

Gastric glands 107

Gastric juice 108

Action of 108

Glands 99

Salivary 102

Gastric 107

Mesenteric . . . . . 123

Lymphatic 124

Ductless 125

Suprarenal 125

Thymus 125

Thyroid 125

Sebaceous 188

Lachrymal 259

Glottis 279

Hair, Growth of 189

Color of 189

Structure of 188

and nails, Care of . . . 198

Hand 37

as a marvel of mechan-
ism 38

Haversian canals 25

Head, Bones of ..... 27

Hearing, Sense of .... 263

Mechanism of .... 269
Effect of tobacco and

alcohol on 272

Heart 140

Valves of 142

Heart, Blood vessels connected

with 143, 144

Rhythmic action of . . 150

Impulse of 150

Sounds of 151

Nervous control of . . 151

Effect of alcohol on . . 158

Effect of tobacco on . . 1 58

Heat, Animal 178

Sources of 178

Hepatic lobules 113

duct 114

Hiccough 174

Hip bones 34

Histology defined .... 6

Humerus 36

Hygiene defined 6

Hyoid bone 30, 277

Hypermetropia 255

Ileum no

Infection, pulmonary, Dangers

of 177

Influenza 297

Injured, First aid to . . . . 302

Inspiration 167

Intestine, Small 109

Coats of small . . . . 1 1 1

Digestion in small . . . 118

Large in

Iris and pupil 250

Jejunum no

Joints 40

Formation of .... 40

Different kinds of ... 42

Katabolism defined .... 5

Kidneys 201

General structure of . . 201

358

Life and Health

PAGES

Kidneys, Function of ... 202

Minute structure of . . 202

Action of, how modified . 204

Effect of alcohol on . . 205

Labyrinth 267

Lachrymal apparatus . . . 258

bones 29

glands ........ 259

caruncle 259

Lacteals 122

Landmarks of the body . . 319

Larynx 162, 277

Leg, Bones of 39

Lens, Crystalline 252

Levers in the body . . . 57, 58

Life, Incessant change of . . 4

Ligaments 42

Limbs, Upper 34

Lower 38

Liver 112

Lobules of 113

Blood supply of . . . . 115

Work done by . . . . 115

Formation of urea by . . 117

Glycogenic function of . 117

Effect of alcohol on . . 133

Long sight 255

Lungs, General structure of . 165

Minute structure of . . 166

Effect of alcohol on .181, 182

Lymph 147

Lymphatics 124

Work done by . . . . 124

Malar bone 29

Mastication 99

Maxillary, Superior .... 29

Inferior 30

Meals, Suggestions about . . 128

Meats as food 83

Medulla oblongata . . . . 215

Function of 215

Membrane, Synovial .... 57

Serous 141

Membranes of brain . . . . 214

Membranous sac 268

Mesenteric glands . . . . . 123

Mesentery in, 123

Metabolism defined . . . . 5

Metacarpal bones 38

Metatarsal bones 40

Microscope, Use of . . . . 318

Milk v • • • 83

Mineral foods 82

Morphology defined .... 5

Mouth 99, 162

What may be seen in . . 276

Movement, Mechanics of . . 57

Muscles, Kinds of ... 49, 55

Microscopic structure of . 50

striated, Structure of . . 50

unstriated, Structure of . 51

unstriated, Action of . . 52

how named 55

of chest and back ... 59

of head and neck ... 59

of lower extremities . . 61

of shoulder and arm . . 61

Effect of alcohol on . . 62

Effect of tobacco on . . 63

Effect of exercise on . . 66

Review table of .... 65

Muscular coordination ... 67
contraction .... 52, 54

movements 70

fatigue 71

sense 241

Myopia 255

Index

359

Nails 189

Care of 198

Nasal bones 29

duct ....*.... 259

Near sight 255

Nerve cells 207

fibers 207, 208

cells and fibers,Function of 209

Nerves, General structure of . 208

Cranial 217

Cranial distribution and

functions of . . . . 217

Spinal 219

Motor 220

Sensory 220

Nervous system, General view

of 206

compared to telegraph

system 209

Divisions of 210

Effect of alcohol on . . 230

Effect of tobacco on . . 235

Nitrogenous foods .... 80

Non-proteid vegetable foods . 85

animal foods 85

Nose, Bleeding from .... 306

Foreign bodies in ... 308

Occipital bone 27

QEsophagus 104

Old sight 254

Opium 233

Poisonous effects of . . 233

Victim of the, habit . . 234

Optic nerve 248

Organic compounds .... 8

Oxidation 178

Pain, Sense of 242

Palate bones 29

Pancreas 117

Pancreatic juice 118

Papillae, Kinds of 242

Parietal bones ...... 27

Patella 40

Pelvis 34

Pepsin 108

Pericardium 140

Periosteum 23, 25

Peritoneum in

Phalanges 38, 40

Pharynx 104

Physical exercise 66

Physical exercises in school . 76

Practical points about . 77

Physiology defined .... 5, 6

in schools I

Lessons taught by ... 2

Experimental work in . 317

Pleura 165

Pneumogastric nerve . .152,217

Poisoning, Treatment of . . 313

Poisons 313

and their antidotes . . . 313

Practical points about . 314

common, Table of . . . 315

Antidotes for 315

Prominent symptoms of . 315

Portal circulation 149

Portal vein 113

Presbyopia 254

Pressure, Where and how to

apply 304

Proteids 9, 80

Proteid vegetable foods . . 84

Protoplasm 10

Pulmonary artery 148

veins 146

circulation 147

infection 177

36°

Life and Health

PAGES

Pulse 154

wave '. 155

wave, how modified . . 155

Pupil of the eye 250

Radius 36

Receptaculum chyli .... 123

Rectum 112

Reflex action, Importance of . 223

in spinal cord .... 222

Reflex centers in the brain . 222

Renal secretion 204

Respiration, Nature and object

of 161

Essential step in . . . 161

of the tissues 161

Mechanism of . . . . 168

Nervous control of . . . 1 69

Effect of, on the blood . 171

Effect of, on the air . . 172

Changes of air in . . . 173

Modified movements of . 174

Effect of alcohol on . . 181

Effect of tobacco on . . 182

artificial, Method of . . 312

Respirations, Frequency of . 168

Rest, for the muscles ... 72

Need of 227

Benefits of 228

Retina 250

Ribs 33

Sacrum 32

Saline and mineral foods . . 82

Saliva 102

Salivary glands 102

Salt as food 88

Salts, Inorganic, in the body . 8

Scalds or burns 306

Scapula 35

Scarlet fever

School, Physical exercises in .

Sclerotic coat

Secretion . *

Semicircular canals . . . .

Semilunar valves

Sensation, Condition of . .
Sensations, General . . . .
Sense, special, Organs of . .

organ, Essentials of . .
Serous membranes . . . .
Sick room, Location and ar-
rangement of . . . .

Ventilation of . . . .

Hints for

Additional hints for . .

Helps for

Sighing

Sight, Sense of

Skating,swimming, and rowing
Skeleton

Study of

Review analysis of . . .
Skin, General structure of. .

as complex organ . . .

Color of

regulator of temperature .

Action of, how modified .

Absorbent powers of . .
Skull

Sutures of

Sleep, a periodical rest . . .

Amount of, required . .

Practical rules about . .
Smell

and taste

Sense of

Sneezing

Sobbing

Sounds, Articulate . . . .

PAGER

298

76

249

99
267
M3
238
237
239
238
141

299
298

299

300

300

174

247

75

24

21

48

I85

I85

188
192
193
194
27

30
228
229
229
245
246
246
174
174
282

Index

361

Special senses 237

Speech 281

Sphenoid bone 27

Spinal column 31

Spinal cord 218

Structure of 218

Functions of 220

Reflex center in . . . . 221

Reflex action of .... 222

Spinal nerves 219

Spleen 125

Sprains 44

Stammering 283

Starches and sugars .... 81

Sternum 34

Stomach 105

Coats of 107

Digestion in 108

Strabismus 258

Stuttering 283

Sunstroke 310

Suprarenal capsules . . . . 125

Sutures of skull 30

Sweat ......... 191

glands 189

Composition and . quan-
tity of 191

Visible . . 191

Secretion of, and nervous

control 193

Number of, glands . . . 190

Sympathetic system . . . . 224

General functions of . . 226

Special functions of . . 226

Synovial membrane .... 57

sheaths and sacs ... 57

Taste, Sense of 244

Effect of tobacco and alco-
hol on 245

Taste, Modifications of the

sense of 245

Tea 89

Tear gland and tear passages 259

Tears 260

Technical terms defined . . 5

Teeth 100

Development of ... 101

Structure of 101

Proper care of .... 129

Hints about saving . . 132
Temperature, Regulation of

bodily 179

Skin as a regulator of .180

Adjustment of . . . . 181

Sense of 242

Temporal bones ..... 27

Tendon of Achilles .... 56

Tendons 56

Thoracic duct 123

Throat 276

Care of 283

Effect of alcohol and to-
bacco on 284

Foreign bodies in ... 308

Thymus gland 125

Thyroid gland 125

cartilage 277

Tibia 39

Tissue, White fibrous ... 17

Yellow elastic .... 17

Adipose 18

Areolar 18

Adenoid 19

Tissues, Epithelial .... 14

Epithelial, classified . . 14

epithelial, Varieties of . . 15

Connective 16

Functions of 16

Tobacco, Effect of, on bones 47

362

Life and Jfcallh

Tobacco, Effect of, on muscles 63
Effect of, on physical

development .... 77
Effect of, on digestion . 134
Effect of, on the heart . 1 58
Effect of, on the respira-
tory passages .... 182
Effect of, on mental abili-
ties 235

Effect of, on the nervous

system 235

Effect of, on taste . . . 245

Effect of, on vision . . . 263

Effect of, on hearing . . 272
Effect of, on throat and

voice 284

Tongue 242

as organ of taste . . . 242

Touch, Organs of 240

Sense of 240

how educated .... 241

Trachea 163

Trunk, Bones of 31

Tuberculosis 3I7~33I

a widespread and deadly

disease 317

a very old disease . . . 317

what it is 318

Discovery of germ of . . 318
Parts of body infected

with 318

Growth and history of

germ of 319

as a contagious disease 319, 320
how germs are scattered 320
Chief mode of communi-
cating 321

Danger in sputum of, 321, 322

Early symptoms of . . 322

not inherited 322

Tuberculosis, in animals . . 323

Crusade against .... 323
Agencies at work in this

crusade 324

Camps, open-air schools,
and sanatoriums in
treatment of . . . . 325
Open-air treatment of . . 326
Education of general pub-
lic in regard to . . . 327
Suggestions on protect-
ing health .... 327, 328
How school children may
help in crusade against

328-330

Turbinated bones 29

Tympanum, Cavity of ... 266

Typhoid fever 298

Ulna 36

Urine 204

Vaccination 295

Valve, Mitral . .' . . . v 142

Tricuspid 142

Valves, of the heart . . . . 142

Semilunar 143

Vegetable foods .... 84, 85

Veins ......... 145

Flow of blood in . . . 146

Ventilation, Object of . . . 178

of sick room 298

Vermiform appendix . . . . 112

Vertebrae, Spinal 31

Vestibule of ear ...... 267

Vision, Common defects of 254-258

Effect of tobacco on . . 263

Vivisection and dissection . . 319

Vocal cords 278

Voice, Mechanism of ... 279

Index

Voice, Factors in the produc-
tion of ......

Care of .......

Effect of alcohol on . .
Effect of tobacco on . .

284
284

74

Walking, j umping, and running
Waste, how made good by

food 79, 98

Waste material, Nature of . 184

Waste products, Eliminationof 184

Formation of 184

Water, as food 82, 88

Amount of, in various

tissues 83

Need of pure 88

Whispering 283

Yawning

174

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