", ' X ■ 
■ ■ DR. ROBERT KOCH 
Who discovered the germ of tuberculosis which kills over four hundred 
people daily in tne United States. THE 
HUMAN BODY AND HEALTH 
REVISED 
A TEXTBOOK OF ESSENTIAL ANATOMY, 
APPLIED PHYSIOLOGY, AND 
PRACTICAL HYGIENE 
J 
BY 
ALVIN DAVISON, M.S., A.M., Ph.D. 
*"late professor of biology 
LAFAYETTE COLLEGE 
ADVANCED 
AMERICAN BOOK COMPANY 
NEW YORK. CINCINNATI CHICAGO 
BOSTON ATLANTA Copyright, 1908, by 
ALVIN DAVISON. 
Copyright, 1924, by 
AMERICAN BOOK COMPANY. 
HUMAN BODY, REVISED, ADV. 
W. P. I 
MADE IN U.S.A. PREFACE 
The most noted of England's prime ministers said, "The 
first duty of the statesman is the health of the people." One 
of our own statesmen asserts that the greatest asset of this 
nation is the health of its citizens. Inasmuch as recent science 
has shown clearly the cause and prevention of many diseases, 
it is important that this knowledge should form a part of every 
individual's equipment for the duties of life. The greatest 
enemies of the human race are microbes, which annually lay 
prostrate in this country and Europe seventy million people, 
of whom three million die. The microbes feeding on human 
blood have caused the destruction of armies and the downfall 
of a nation. On this account a knowledge of these infinitely 
small forms of life is of vast importance. 
Since the foundation of many diseases is laid during child- 
hood, and since new ideas are accepted most readily in youth, 
every boy and girl during school years should be carefully 
and thoroughly instructed as to the cause of human wretched- 
ness and the means of preventing it. The numerous text- 
books on elementary physiology have largely neglected the 
discussion of facts relating to public health. As a result not 
one in a hundred graduates of our public schools could state 
any evidence showing whether vaccination is beneficial or 
harmful, or describe how malaria, diphtheria, and yellow fever 
are acquired, and how they may be prevented. 
The pupils have spent much time in learning meaningless 
words, but when information is sought concerning the evidence 
that typhoid fever is caused by drinking polluted water they 
remain silent. A pupil is rarely found who can state clearly 
how the fact has been established that bacteria produce dis- 
5 6 
PREFACE 
ease. In consequence very many do not yet believe that 
disease is preventable, and so pay little heed to the laws made 
by the state for the welfare of its people. 
The facts that in this country nearly one hundred persons 
die daily of typhoid fever and four times as many from tuber- 
culosis, and that these diseases are largely preventable, are 
unknown to most public school pupils. As a result the people 
continue to use bad air, bad water, and bad food. Holmes 
wrote fifty years in advance of his age: - 
" God gave his creatures light and air 
And water open to the skies ; 
Man locks him in a stifling lair 
And wonders why his brother dies." 
This book contains a sufficient amount of anatomy to enable 
the pupil to understand the physiology upon which is based 
much of the hygiene. Numerous original diagrams, drawings, 
and halftones from photographs have been introduced to im- 
press upon the learners the most important truths relating to 
the human machine. For many of the drawings, I am in- 
debted to Professor W. H. Reese of Muhlenberg College. 
A considerable number of pages have been given to a dis- 
cussion of the effects of alcohol on human society, showing 
that its power for evil is far more marked in producing poverty 
and crime than in wrecking the physical health. 
That a knowledge of practical hygiene does prevent waste 
of life, is shown by the fact that the death rate per thousand 
declined from thirty in 1870 to less than nineteen in 1905. 
Diphtheria, tuberculosis, yellow fever, and malaria claim fewer 
victims every decade, and when knowledge such as these pages 
afford reaches all our citizens, the vital records will show a 
still more rapid decrease in the death rate. CONTENTS 
CHAPTER PAGE 
I. Introduction ... 9 
II. Plan of the Body . . 14 
III. Composition of the Body ...... 22 
IV. Life Processes 28 
V. Food and its Uses . 35 
VI. Microbes and Molds 46 
VII. Milk . . 54 
VIII. Narcotics and Stimulants 68 
IX. The Digestive System 76 
X. How Food is Digested 90 
XI. The Blood 106 
XII. The Circulatory System 114 
XIII. The Respiratory System 132 
XIV. Air and Health . 151 
XV. Alcoholic Drinks and their Effect on the Human 
Race • . . . . 163 
XVI. The Excretory System 175 
XVII. The Osseous System or Bones 191 
XVIII. The Muscular System 203 
XIX. How the Nervous System is Constructed . . . 215 
XX. How the Nervous System Works ..... 225 
XXI. The Sense Organs ........ 237 
XXII. The Sense Organs (Continued') ..... 246 
7 8 
CONTENTS 
CHAPTER PAGE 
XXIII. The Cause of Disease 259 
XXIV. The Prevention of Disease 272 
XXV. Accidents and Emergencies ... . . 294 
Pronunciation and Explanation of Difficult Words . . 307 
Index . . . . « . . « . . = » 315 THE HUMAN BODY AND HEALTH 
I. INTRODUCTION 
The Meaning of Anatomy. - The science of anatomy de- 
scribes the parts and structure of the body. It teaches 
the relative locations of the many organs, such as the heart, 
lungs, and liver. Without a knowledge of anatomy it 
would be impossible to understand the operation of the 
human machine. Ignorance of its operation prevents 
the proper management, protection, and care necessary 
to health. Health is wealth, and the lack of health is 
responsible for much human misery. An understanding 
of the parts of the body concerned in the preparation of 
the food, of the vessels conveying it through the body, 
and of the structures for admitting air and getting rid of 
waste materials, may be a great aid to human happiness. 
The Meaning of Physiology. -This science tells the 
function, or use, of each part of the human machine. It 
explains how the food eaten is used to build up muscles, 
bones, and brain, and how the nerves, heart, and blood per- 
form their duties. The study of physiology helps one to 
understand the necessity of chewing food thoroughly, by 
what means the food is taken from the alimentary canal 
to the head, arms, and legs, and how the brain causes the 
body to move. It shows how the lifeless bread, meat, and 
milk may become a part of the living human body, and 
9 10 
INTRODUCTION 
how potatoes, oatmeal, or fat meat when eaten may help 
to keep a person warm. 
Importance of studying Physiology. - Knowing how the 
stomach and intestines act in making the food into a 
solution to be received by the blood has resulted in finding 
out the causes of dyspepsia, and also how to prevent it 
and how to cure it. The discovery of the fact that the 
germs in old or unclean milk often cause disease and death 
among infants, has made it possible to prevent much 
suffering and to save many lives. Until the real use of 
the blood was understood, patients suffering from various 
ailments were bled in order to remove the supposedly 
bad humors from the body. 
Prior to the Revolutionary War the insane were com- 
monly thrust into sunless dungeons, and chained to the 
walls with iron bands riveted about the waist or neck 
because they were thought to be demons. Since physiology 
has shown the relation of the mind to the brain and the 
influence of health upon the brain, the insane have been 
cared for in a more humane manner. As a result very 
many recover their health and are restored to their friends. 
It is only by a clear understanding of the actions of the 
various organs that one can know when they are out of 
working order and the kind of remedy to be applied to 
cure the sickness. The prevention of sickness is, how- 
ever, far more important than curing it. The greatest bene- 
fit, therefore, derived from the study of physiology is the 
information which enables us to understand hygiene. 
The Meaning of Hygiene. - The science of hygiene shows 
how one should live in order to keep the body in a healthy 
state. It explains how any one may avoid taking cold, and IMPORTANCE OF STUDYING HYGIENE 
11 
how to avoid such diseases as yellow fever, typhoid fever, 
tuberculosis, and malaria. It teaches what to do in case of 
an injury to the body, such as the breaking of a leg or the 
cutting of a blood vessel. The success of the Japanese 
army in the late Russo-Japanese War was in part due to 
the strict observance of the laws of hygiene by the 
soldiers and officers of Japan. Army physicians declare 
that in most wars before the present century, negligence 
in regard to the laws of hygiene resulted in more deaths 
than were caused by the bullets of the opposing army. 
Importance of studying Hygiene. - A sound body is a 
fortune. Sickness is expensive. Knowing how to pre- 
vent illness is worth more than knowing how to cure it. 
Before 1796, smallpox was the most dreaded and the com- 
monest of all diseases. In cities having a population 
of 100,000, more than 2000 cases of smallpox occurred 
every year, resulting in hundreds of deaths. Some cities 
suffered from much more severe epidemics. In 1721, 
Boston, with a population of 11,000, had 5989 cases of 
smallpox. Eighteen thousand people died of this disease 
in Iceland during the years 1707-1709. This pest, which 
once was a great affliction to the civilized world, has now 
become almost unknown in many regions, owing to vacci- 
nation. About one fourth of all children born die in a 
few months. This is due largely to ignorance and care- 
lessness concerning hygiene, on the part of the parents. 
Recent investigations indicate that one half of the 
1,000,000 people who died of tuberculosis in this country 
during the years 1900-1906 might have escaped the disease, 
or might have recovered from it, by observing the laws of 
hygiene. Knowing and heeding what hygiene teaches 12 
INTRODUCTION 
would have enabled 100,000 of the 200,000 victims of 
typhoid fever in the year 1906 to escape the malady. 
Living in a hygienic way has, in Massachusetts, decreased 
the death rate from tuberculosis one half since 1875. 
Cities where the water and milk supply are managed 
according to the demands of hygiene have less than one 
half as many deaths from typhoid fever as other cities simi- 
larly situated but making no special effort to secure pure 
milk and pure water. Four hundred thousand of the 
1,600,000 deaths occurring yearly in the United States 
could be prevented if the people understood hygiene and 
lived in accordance with its teachings. Students of this 
science are confident that 3,000,000 of the 8,000,000 cases 
of serious illness could be averted by hygienic living. 
Value of Hygiene to the Young. - Success in life depends 
largely upon health. Health depends much upon habits. 
Habits are formed in youth. The youth is to the future 
man what the roots are to a tree. The foundation for 
much of the illness in later life is laid by the boy and girl 
during school years. That instruction which helps the 
pupils to understand the care of the body, and the true 
value of fresh air, proper food, exercise, and cleanliness, 
will add much to the wealth of a nation and the happiness 
of its people. 
Suggestions for the Teacher 
To make the subjects of Physiology and Hygiene of real value, the 
teacher must impress the more important truths upon the pupils by 
calling attention to specific facts related to the pupils' own welfare. 
A few demonstrations and simple experiments are of great use in 
helping the learners to get correct and well-fixed ideas. Material for 
showing important structures, such as the heart, larynx, and brain of 
a calf or a sheep, may be preserved for years in a stone jar or large- SUGGESTIONS FOR THE TEACHER 
13 
mouthed fruit jar containing a five per cent solution of formalin. 
This is made by pouring about one third of a teacupful of formalde- 
hyde, to be had at any drug store, into a pint of water. 
The writing of short essays on certain topics of vital importance 
not only will widen the interest and knowledge of the pupils, but also 
will serve to give valuable training in expression. A few bulletins 
and reference books may be made to furnish the information for such 
exercises. Many of the states publish sanitary bulletins or health 
circulars which may be had free of charge by addressing the State 
Board of Health at the capital of the state. The following valuable 
bulletins will be sent free to those requesting them from the Depart- 
ment of Agriculture, Washington, D.C. : Sanitary Milk Production; 
Rabies or Hydrophobia; Sewage Disposal on the Farm; Source and 
Nature of Bacteria in Milk ; Trichinosis, a Danger in the Use of Raw 
Pork; How Insects affect Health in Rural Districts; Bovine Tuber- 
culosis and Public Health; Butter Making on the Farm; The Unsus- 
pected but Dangerously Tuberculous Cow; Fish as Food; Eggs and 
their Uses as Food; The Nutritive Value of Foods; The Care of 
Milk ; Milk as Food. 
The following reference books will be helpful to the teacher and 
should be in every school library. 
Overton, Frank, Applied Physiology. American Book Company, 
N.Y. 
Eddy, W. H., Experimental Physiology and Anatomy. American 
Book Company, N.Y. 
Adams, S. H., The Great American Fraud. American Medical 
Association, 103 Dearborn Ave., Chicago. 
Bashore, H. B., Outlines of Practical Sanitation. John Wiley and 
Sons, N.Y. 
Crandall, F. M., How to Keep Well. Doubleday, Page, and Com- 
pany, N.Y. 
Frankland, Mrs. P., Bacteria in Daily Life. Longmans, Green, and 
Company, N.Y. 
Public Health Papers and Reports. C. O. Probst. Columbus, 
Ohio. 
Pyle, W. L., A Manual of Personal Hygiene. W. B. Saunders 
Company, Philadelphia. 
Shaw, E. R., School Hygiene. Macmillan Company, N.Y. 
Warwick, F. J., First Aid to the Injured. Penn Publishing Com- 
pany, Philadelphia. II. PLAN OF THE BODY 
The Cells. - Since the year 1840 it has been known 
that all plants and 
animals are made 
up of one or more 
tiny lumps of mat- 
ter called cells. A 
cell, whether in 
a weed, a worm, 
or man, consists 
mainly of a sub- 
stance named pro- 
toplasm, which is 
like the white of a raw egg. A minute and usually 
spherical body floating 
in the protoplasm is the 
nucleus. The thin sac 
ordinarily surrounding 
the protoplasm is called 
the cell wall. The thin 
membrane between the 
successive layers of an 
onion is formed by a 
single layer of cells 
placed edge to edge. 
Each egg of a toad or 
frog when first deposited. 
Fig. 1. - A cell much enlarged. 1, surface view; 
2, view of the upper part of 1 cut through the 
line ae; p, protoplasm; the dark spot is the 
nucleus and the line around the outside is the 
cell wall. 
Fig. 2. - Slipper animalcules in a drop of 
water. Photographed through the micro- 
scope. 
14 THE NATURE OF A CELL 
15 
is a single cell, but it is more than thirty times as large as 
the average cell in the human body. 
The Nature of a Cell. - The cell is called the unit of 
life because it is the smallest portion of matter capable of 
independently living, eat- 
ing, and growing. A 
muscle cell, a brain cell, 
or a skin cell will of 
course not continue to 
live long when removed 
from the body, because 
it has no means of get- 
ting food. There are, 
however, in most pools of 
stagnant water thousands 
of free, living cells, each 
of which is an animal or 
plant. One of the largest 
and very easily found 
forms of life consisting of 
a single cell is the slipper 
animalcule, a million of 
which may be present in 
a quart dish of water. 
By adding to a glass of 
pond water a small bunch 
of hay or dead grass, and allowing it to stand in a warm 
room a week or ten days, numerous slipper animalcules 
may be grown. If a drop of water containing them is 
placed on a glass slip, they appear to the naked eye 
like tiny white specks floating about. 
Fig. 3. - A compound microscope such 
as is used to study the cells of the 
body and disease germs. 16 
PLAN OF THE BODY 
A One-celled Animal. - By means of the microscope the 
slipper animalcule may be seen to have the general shape 
Fig. 4. - Drawings of sections of cells. Magnified, b, bone cell; c, 
epithelium cell from the intestine; e, flat epithelium cell from the 
mouth; f, fat cell; n, nerve cell from the brain; m, muscle cell. 
of a slipper, though its outline changes much when it 
rubs against an object. The delicate cell wall is elastic 
and transparent, and is 
covered with fine hair- 
like processes called 
cilia, by moving which 
it swims rapidly. A 
faintly darker oval spot 
near the center is the 
nucleus. It takes in 
food consisting chiefly 
of tiny plants called 
bacteria, through a 
groove on one side. The 
food, when within the 
protoplasm, is dissolved, 
and some of it becomes 
Fig. 5. - Slipper animalcule beginning to 
divide and thus to form two cells, each of 
which will swim away as a distinct animal. 
The nucleus has already divided. Photo- 
graphed through the microscope. KINDS OF CELLS 
17 
a part or the animal itself, while the rest is pushed out 
through the cell wall. This tiny living thing has no 
bones, muscles, liver, stomach, blood vessels, lungs, or 
nerves, yet it moves, eats, and gives off the same kind of 
substances as those cast out by the lungs and kidneys 
of man. It is 
affected by heat, 
cold, light, and 
touch. This sin- 
gle cell performs a 
dozen duties, for 
each of which in 
the human body 
there is a separate 
group of cells. 
Kinds of Cells. - 
In the human 
body there are 
more than a score 
of different kinds 
of cells. Each 
kind has a special 
duty to perform 
and is worthless 
for any other serv- 
ice. The muscle cells are threadlike and can become 
shorter or longer to move the bones. The fat cells are 
nearly spherical, while the cells lining the stomach and in- 
testines are columnar and take from the blood something 
which they change into a juice to dissolve the food. The 
nerve cells are of various shapes, but most of them have 
Fig. 6.- Frog's eggs photographed through the mi- 
croscope. A few hours earlier each egg was 
a single cell. Some are now se«n to be made of 
four cells, some of eight cells, aud others of a 
greater number of cells. 
DAV. PHYS. 2 18 
PLAN OF THE BODY 
several branching processes, one of which may be two or 
three feet long. While among the lowest animals one 
cell serves many pur- 
poses, in all the higher 
creatures there is a 
different group of cells 
for each of the processes 
of life, such as eating, 
moving, and feeling. 
This separation of the 
cells into companies, 
each with its own 
special work, is known 
as the physiological di- 
vision of labor. 
Growth of Cells. - 
The slipper animalcule 
never gets any larger 
than the point of a pin. As soon as rich food tends to 
make it grow, the nucleus divides into two parts, and a 
few minutes later a constriction, or furrow, appears cross- 
wise of the body. The furrow continues to deepen, so 
that in less than a half 
hour the tiny creature 
has separated into two 
animals. This marvelous 
process may be easily seen 
by placing on a glass 
slide, under the low power 
of the microscope, a drop 
of water containing the 
Eig. 7. - A bit of muscle as thick as a hair, 
photographed through the microscope. In 
one place the several fibers are separated 
to show the fibrous connective tissue bind- 
ing the muscle fibers together. 
Fig. 8. - Epithelial cells forming the tissue 
lining the mouth and esophagus, n, 
nucleus. Magnified. ORGANS 
19 
small beings. These two new animals in a few hours grow 
to full size, and then each divides to form two others. 
Thus in a few days from one tiny animal may come a thou- 
sand. In the same way the cells of the body are increased, 
but instead of each leading a separate existence they all 
cling together in one mass. When the upper cells of the 
skin are rubbed off, the 
ones in the lower layer 
divide, and so produce 
a new lot from week to 
week. 
The Tissues. -A com- 
bination of cells of a 
similar kind forms a 
tissue. The muscle cells 
constitute the muscular 
tissue known as lean 
meat (Fig. 7). The 
nerve cells make up the 
chief part of the nerve 
tissue composing the brain, spinal cord, and nerves. The 
epithelial cells, covering the entire body and lining the 
alimentary canal and other tubes, constitute the epithelial 
tissue (Fig. 8). Numerous cells and fibers serving to bind 
together the parts of all the other tissues are known as 
connective tissue (Fig. 9). It is this that holds the skin to 
the muscles and unites the muscles to the bones. It ap- 
pears as fine weblike threads in a piece of boiled beef 
picked to pieces on the dinner plate. 
Organs. - A group of tissues having a special use is 
called an organ. The heart is an organ for pumping 
Fig. 9.-Connective tissue fibers photo- 
graphed through the microscope. 20 
PLAN OF THE BODY 
blood, the stomach an organ to 
digest food, and the brain an 
organ concerned in thought. 
Systems. - Several organs, 
each of which performs a part 
of the same general process, con- 
stitute a system. The digestive 
system is composed of the organs 
used in digestion. The heart 
and blood vessels make up the 
circulatory system. The lungs 
and the air passages of the nose, 
throat, and windpipe constitute 
the breathing or respiratory 
system. The kidneys belong to 
the excretory system. All the 
bones form the bony or osseous 
system, and the muscles form the 
muscular system. The brain, 
spinal cord, and nerves through- 
out every part of the body consti- 
tute the nervous system. 
Each system is dependent on 
the others for its health. When 
the cells of any tissue do not 
work properly, the body becomes 
sick. To keep the body well, 
each system, each tissue, and 
each cell must do its own part 
of the work in preparing, digesting, and using food, and 
also in giving off waste products of the body Fresh air, 
Fig. 10.-Diagram showing the 
position of the organs of the 
human body, viewed from the 
side, a,aorta; op,vermiform 
appendix; c, large intestine; 
d, diaphragm; e, pharynx; 
g, lung; &, kidney; I, canal 
for spinal cord ; m, branch of 
aorta to the leg; n, pancreas; 
np, spines of vertebrae; o, 
esophagus; s,spleen; t, vena 
cava,or great vein ; tr,trachea. SUGGESTIONS FOR THE TEACHER 
21 
daily exercise, good food, and temperate habits are the 
surest means of keeping the systems in working order. 
Questions 
1. Where are cells found? 2. Name the three parts of a cell. 
3. What is a cell? 4. Where can you get animals composed of only 
one cell? 5. Why cannot a cell removed from man's body continue 
to live? 6. How does the slipper animalcule live? 7. Name several 
kinds of cells. 8. Describe how the cells differ in shape. 9. Describe 
the growth of cells. 10. Define a tissue. 11. Name some tissues. 
12. What is an organ? 13. How many systems in. the body? 
14. What is the best way to keep well ? 
Suggestions for the Teacher 
1. Frog's eggs, appearing like dozens of shot in a mass of jelly- 
like substance as large as one's fist, may be found during April in 
ponds, and used to show how cells multiply. If the lower half of 
the eggs are white, each is probably a single cell, and if they are kept 
in water, furrows will appear on the surface as the cells increase in 
number. The eggs may be preserved in a jar containing a half pint 
of water to which has been added a half of a teacupful of for- 
maldehyde. 
2. Secure a piece of transparent membrane just inside of the outer 
layer of an onion, and lay it in a drop of water on a piece of glass. 
By looking through it toward the light with a common magnifying 
glass, thousands of rectangular cells may be seen. 
3. Slipper animalcules may be produced in abundance by placing 
in a glass of stagnant water some dry grass and any plant found grow- 
ing in water. The glass should be kept for a week or more in a warm 
room. The animals appear as minute oval bodies in a drop of water 
placed on a glass slide and examined with a common magnifying 
glass. They are just visible to the naked eye. III. COMPOSITION OF THE BODY 
Water.-The body of a person weighing one hundred 
pounds contains in it about sixty-five pounds of water. 
If an ounce of beef is placed in a warm but not hot oven 
for a day, it will lose three fourths of its weight. This 
shows that the muscles of our body, which have about the 
same composition as lean beef, consist of only a fourth 
part solid material. Nearly nine tenths of the blood 
and one half of the bones are made of water. 
Use of Water in the Body.-Without water the blood 
could not circulate through the tissues to carry food 
to them and bring away the waste products. Dry 
sugar will not go through a paper or membrane, but 
when dissolved in water it passes through readily. In 
the mouth, stomach, and intestines the water aids in 
softening and dissolving the food so it may pass into the 
blood. Muscles cannot contract without water, as they 
would be hard and fixed like a piece of dried beef. The 
passing off of water through the skin helps to keep the 
body cool. In fact, no organ could do its work without 
water, the amount of which taken in daily with food and 
as drink is about two quarts. 
Solids. - One third of the body is composed of solid 
materials consisting chiefly of the following substances: 
1. mineral matter, such as salt, soda, lime, and iron ; 
2. proteids, like the white of an egg ; 3. fats, such as lard 
22 PKOTEIDS 
23 
and tallow; 4. carbohydrates, of which sugar and starch 
are good examples. The mineral matter makes up much 
of the bones, but in most other parts of the human 
structure proteids are present in the greatest abun- 
dance. 
Mineral Matter. - This is the ashes left after burning 
a piece of wood or flesh. The mineral substances form 
about one half of a 
bone and are chiefly 
compounds of lime. 
More than a teacup- 
ful of common salt is 
distributed through- 
out the body. Iron 
in amount sufficient 
to make a piece as 
large as a cent oc- 
curs in the liver, blood, and hair. A few other mineral 
compounds are present in various organs, but no gold, 
silver, lead, or copper are constituents of the human 
structure. As minerals are constantly passing out of the 
body in the excretions, a new supply must be furnished 
by the food. Milk, meat, eggs, and vegetables contain 
all the mineral substances required by the body. 
Proteids. -These make up four fifths of the solid part 
of the muscles and are present in all the tissues. The 
easiest form of proteid to observe is albumin which with 
water forms nearly all the white portion of a hen's egg, 
and is also the chief part of the protoplasm in the cells of 
the body. Albumin is so named because when heated to 
near the boiling point it becomes white, and it is then 
Fig. 11. - Mineral matter in muscle, a, piece of 
fresh muscle; b, the mineral matter remaining 
after the muscle was burned. 24 
COMPOSITION OF THE BODY 
changed from a fluid to a solid state. The change of a 
proteid from a liquid to a solid is called coagulation. 
The clotting of blood is the coagulation of the proteid 
in the blood. The clabber of sour milk is the coagulated 
casein which is the proteid of milk. Gluten, the proteid 
of wheat, may be separated from the other parts of the 
flour by placing flour in a handkerchief or muslin bag, 
and kneading or squeezing it ten minutes in a pan of 
water. The sticky 
and stringy ma- 
terial left in the 
bag is the proteid. 
Fats. - Fats are 
found in nearly all 
parts of the body. 
They constitute 
nearly one tenth of 
the brain, one fifth of the nerves, while more than four 
fifths of the tissue called adipose, or fatty, is made of 
pure fats. The fat of the cow is known as tallow, and that 
of the hog lard. In the living body the heat keeps the 
fats in a liquid form. Fats which remain liquid at the 
temperature of a living room are called oils. Linseed 
oil, olive oil, and castor oil are examples of fats derived 
from plants. 
To determine the presence of fat in a substance, place it 
on unglazed paper and warm it a few minutes. If fat is 
present, it will melt and soil the paper. The fat of the 
body is stored in cells so small that a bunch of fifty would 
be no larger than the head of a pin. Most of our fat is 
made from the sugars and starch eaten, 
Ftg. 12. - Fat cells in the connective tissue just 
under the skin, b, blood vessel; f, oil; n, nu- 
cleus. Magnified. USE OF FAT 
25 
Properties of Fats.-Pats will not form a lasting mix- 
ture with water; but if the two liquids be shaken in the 
same bottle, the fat will in a few minutes rise to the top. 
If a few drops of ammonia or a piece of potash is added to 
the liquids before shaking, the fat is then broken up into 
tiny globules and will remain scattered throughout the 
mixture. This is called an emulsion. 
The fats eaten form 
an emulsion in the in- 
testines before they 
pass into the blood. 
Milk is a natural emul- 
sion, and therefore an 
easy food to digest. A 
drop of milk under the 
high power of the mi- 
croscope will show over 
a thousand globules of 
fat. When milk stands 
a few hours, many of the 
globules rise to the top 
and form a layer of cream. 
When any fat is heated with a solution of potash or 
soda and water, soap is formed. This process is called 
saponification. Glycerine is made at the same time. 
Use of Fat. - The layer of fat just beneath the skin is 
from one tenth to five tenths of an inch thick and pro- 
tects the body from the cold. The living processes going 
on in the body cause the fat to be changed into carbon 
dioxide and water. This change produces heat to warm 
the body just as burning a tallow candle makes heat. 
Fig. 13.-Part of a drop of cream photo- 
graphed through the microscope to show 
the fat globules. COMPOSITION OF THE BODY 
26 
Bat stored in the body can be used as food by the 
muscles, heart, and brain when one is not able to procure 
or eat food. A man named Tanner lived forty days with- 
out taking any food, and during this time he lost thirty- 
six pounds. Almost all of this was fat, but there was 
some loss from the 
other tissues. The fat 
surrounding some of the 
organs, such as the eye 
and kidney, is useful in 
protecting them from 
injury. 
Carbohydrates. - 
These are the starches 
and sugars. More than 
two thirds of the solid 
part of vegetable foods, 
such as corn, wheat, 
peas, and potatoes, con- 
sists of starch. It oc- 
curs in the form of little 
grains which may be seen by placing the scrapings of 
a potato under the microscope. Potato starch grains are 
somewhat egg-shaped, but corn-starch grains are more 
cubical. If starch is chewed in the mouth for several 
minutes, the saliva will change it into sugar. A great 
deal of starch is present in green fruit, such as apples, 
pears, and cherries, but when they become ripe, the 
starch is changed to sugar. 
Use of Carbohydrates. - Starch and sugar, by means of 
the living cells, are changed into carbon dioxide and 
Fig. 14. - A tiny slice of potato showing 
three of the cells full of starch grains. 
Magnified. SUGGESTIONS FOR THE TEACHER 
27 
water, and thereby give off heat. This helps to keep the 
body warm. At the same time, power to move the mus- 
cles is also furnished. The starch and sugar not used for 
these two purposes are changed into fat and stored up in 
the body. 
Questions 
1. How much of the body is composed of water? 2. How can you 
separate the water from a piece of beef ? 3. In what way is water 
useful to the body? 4. Mention several kinds of solids present in the 
body. 5. Name some minerals in the body. 6. Where have you 
seen a proteid? 7. Describe coagulation. 8. Name three kinds of 
proteids and tell where each is found. 9. State some facts about fats. 
10. How do you learn whether fat is present in a substance ? 11. How 
is soap formed ? 12. Of what use is fat ? 13. In what foods are car- 
bohydrates found? 14. Of what use are carbohydrates? 15. Why 
should more carbohydrates and fats be eaten in winter than in sum- 
mer? 16. Should a banker eat the same kind of food as a black- 
smith? Why? 
Suggestions for the Teacher 
1. Light a match and let it burn up completely to show the min- 
eral matter remaining. 
2. To show coagulation let some milk stand in a glass in a warm 
room one or two days, or pour a teaspoonful of vinegar into the milk. 
3. Place a little of the white of egg in boiling water and note 
the coagulation. 
4. Exhibit some lard, tallow, and castor oil and warm the first 
two in a cup, to show that the fat of the body is in a fluid condi- 
tion. 
5. Put a tablespoonful of water in a bottle or test tube and add a 
few drops of castor oil. Then shake and observe how soon the water 
and oil separate. Now add twice as much ammonia as you did oil 
and shake again. Note that a permanent emulsion results. IV. LIFE PROCESSES 
How Dead and Living Bodies Differ. - Every object in 
the universe is either dead or alive. Movement is not a 
sure sign of life. A trolley car and a locomotive move, as 
do also the earth and the other planets, yet they are dead 
bodies. Some living bodies, such as a blade of grass, a 
flower, or a tree, have no motion in themselves, but they 
may be swayed by the wind. Living bodies are able to 
grow and change their form and size by taking within 
them lifeless material of certain kinds, and by transform- 
ing it into a part of themselves. No dead body can ab- 
sorb material from the soil, as does a tree, and change 
it into the substance of its own body. A nestling bird 
makes bones, flesh, and feathers of the thousands of insects 
brought by the mother. 
The Change from Dust to Man.-Animals and plants 
grow only when they obtain food such as can be built 
into their bodies. Plants feed on substances in the earth, 
such as potash, saltpeter, limestone, and gypsum, but 
much of their food is the carbon dioxide of the air. 
Animals cannot use any of these simple substances, but 
must consume vegetables or animal flesh to nourish them. 
Grass is only a portion of the air and earth made over into 
a new form by sunlight and the action of the tiny sprout 
from the grass seed. Some of this grass carried into the 
cells of the cow's body becomes beef, which, eaten by man, 
28 ELEMENTS OF LIFE 
29 
becomes a part of a human being. Thus indirectly man s 
flesh is made of the air and the dust of the ground. 
When death claims the grass, cow, and man, their bodies 
crumble again to dust and make up part 
of the earth. The crumbling, or decay, 
is produced by molds and millions of 
other tiny plants called bacteria. In this 
way the dead hay or straw, acted on by 
these agents, may appear the next sea- 
son in the form of a field of waving 
grain. This, when ground into flour by 
the mills, becomes, upon being eaten by man, a part of 
the human race. 
Kinds of Compounds. - The three common classes of 
compounds are acids, 
alkalies, and salts. 
Acids are sour and turn 
blue litmus paper red. 
Alkalies are not sour 
and will turn red litmus 
paper blue. Sulphuric 
acid, vinegar, and sour 
milk are examples of 
acids. Potash, soda, 
and ammonia are alka- 
lies. Table salt and 
limestone are salts. 
Elements of Life. - 
The elements most 
abundant in a living body are carbon, hydrogen, oxygen, 
and nitrogen. Carbon composes half of the solid part of 
Fig. 15. - Bacteria 
which change dead 
matter into a food 
for plants. Mag- 
nified. 
Fig. 16. - Separating wood into gas and 
charcoal, p, clay pipe containing hits of 
shavings and covered with mud; a, alco- 
hol lamp; I, flame made by the gas lit as 
it issued from the stem. 30 
LIFE PROCESSES 
lean meat, more than half of a stick of dry wood, and is 
plentiful in nearly all foods eaten. Carbon is the chief 
solid element in muscles, fat, sugars, starches, and wood. 
The other abundant elements are 
gases. If, therefore, some bits of 
wood be heated very hot in a clay 
pipe while the top of the bowl is 
covered with wet clay to keep out the 
air, the gases will go out through the 
stem, and as they issue may be lighted 
with a match. After fifteen minutes' 
heating, carbon, called charcoal, is left 
in the pipe. In a similar way gas for 
lighting houses was formerly made by 
heating soft coal in iron boxes. 
Hydrogen.-This is present in nearly 
all foods and composes two thirds of 
water. It is a colorless gas, and may 
be easily made by pouring some weak 
sulphuric acid into a bottle containing 
a few nails or tacks. The iron pushes 
off the hydrogen, which forms part 
of the acid, and the gas appears in 
bubbles (Fig. 17). It will pass out 
of a glass tube inserted through the 
cork, and will burn when a flame is 
applied to it. This burning is the 
union of the hydrogen with the oxygen of the air. As a 
result water made of hydrogen and oxygen is formed. 
This appears in drops on a bottle held upside down at 
the top of the flame. 
Fig. 17. - Making hydro- 
gen. The bottle con- 
tains five nails and 
weak sulphuric acid. 
To the right of the 
flame of hydrogen at 
the tip of the glass tube 
are two drops of water 
formed by the union 
of the hydrogen com- 
ing out of the bottle 
and the oxygen in the 
air. PROPERTIES OF OXYGEN 
31 
Oxygen. - This is a colorless and odorless gas which 
constitutes one fifth of the air, one third of the water, and 
about one fifth of the solid portion of all living things. 
Many lifeless compounds contain it. 
Oxygen may easily be prepared by heating together in 
a test tube black oxide of manganese and chlorate of pot- 
ash. To catch the 
gas, arrange a bent 
glass tube with its 
one end through the 
cork in the test tube 
and the other pass- 
ing just within the 
mouth of a bottle 
filled with water 
and turned upside 
down in a dish of 
water (Fig. 18). 
The bottle is filled 
with water at first 
to expel the air. 
Properties of Oxygen. - Oxygen is the most important 
of all the elements, and is absolutely necessary for the life 
of animals. No fire can burn without it. It differs from 
the other elements in the fact that it may be made to join 
itself to nearly all the elements. Iron exposed to the 
air rusts. The rust is the union of iron and oxygen, 
and is called iron oxide. Carbon, when heated, unites 
with oxygen to form carbon dioxide. 
When oxygen combines with any substance, the pro- 
cess is named oxidation. The substance with which the 
Fig. 18. - Making oxygen, e, rubber tube; n, 
chlorate of potash and black oxide of manga- 
nese; o, oxygen which is bubbling out from 
the test tube. LIFE PROCESSES 
32 
oxygen unites is said to be oxidized. Burning a match 
means oxidizing the wood. Any piece of timber lying out- 
of-doors slowly rots. 
This is slow oxida- 
tion. The oxygen 
of the air is made 
to combine with the 
wood by means of very tiny plants called bacteria. These 
cannot grow unless 
some moisture is 
present. Oxidation 
produced by living 
cells of the body 
is constantly going 
on within every 
plant and animal, 
and without this 
process life cannot 
continue. 
Oxidation in the 
Body. - The oxy- 
gen of the air is re- 
ceived through the 
nose and windpipe 
into the lungs. 
Here it passes into 
the blood, and is 
then carried to every 
cell in the body, 
where living action causes it to unite with the tissues or 
the food present. As a result heat is slowly produced, 
Fig. 19. - A match being oxidized. 
Fig. 20. - Roots of red clover with swellings 
which are the home of bacteria enabling the 
plant to feed on the nitrogen of the air. OXIDATION IN THE BODY 
33 
just as when the match was quickly oxidized by lighting 
it. Oxidation also produces energy, which makes the mus- 
cles move the body and the other organs do their work. 
When running or working hard, we breathe very last in 
order to get enough oxygen to make the muscles do their 
work. To make the fire burn faster, the draft must be 
opened below to send the air containing oxygen into the 
stove so it may oxidize the wood. The heat thus pro- 
duced may be made to boil water and change it into 
steam, which can be transformed into power to run an 
engine. 
Nitrogen. - This constitutes four fifths of the air and 
forms an important part of most of the tissues of the 
body. It is one of the chief elements in the food of 
plants and animals. Any substance, such as skim-milk 
cheese, containing a large amount of it is called nitrogenous 
material. No animals can make direct use of the nitrogen 
of the air, but some plants, such as clover, beans, and 
peas, are able to get it from the air and use it for food by 
the assistance of bacteria growing on their roots and form- 
ing little swellings like the head of a pin. 
Questions 
1. Give two differences between a dead body and a living body. 
2. How are we able to use air and soil for food? 3. What changes 
dead leaves and wood to dust or earth ? 4. Name five elements. 
5. How does an element differ from a compound? 6. Name three kinds 
of compounds. 7. How does an alkali differ from an acid ? 8. What 
four elements are most abundant in man ? 9. How can you make 
carbon? 10. Describe the preparation of hydrogen. 11. Explain 
oxidation. 12. Why are the drafts of a stove opened below to make 
the fire burn? 13. Why do we breathe faster when at hard work ? 
14. Where is nitrogen found? 15. Why must one eat some nitrogenous 
food? 
DAV. PHYS. 3 34 
LIFE PROCESSES 
Suggestions for the Teacher 
1. Fill the bowl of a clay pipe wTith wood shavings and cover over 
the top with wet clay or mud. Heat over a hot flame, and in five 
minutes the gas issuing from the stem inclined upward may be lit. 
When the gas which is formed from the carbon and hydrogen of th( 
wood ceases to burn, carbon will remain in the bowl of the pipe 
2. Place in a small bottle water to the depth of two inches and 
add a half inch of sulphuric acid. Prepare a tight-fitting cork con- 
taining a hole, through which is thrust a small glass tube. Drop into 
the bottle a dozen tacks or nails, then insert the cork, and after five 
minutes, try lighting the colorless gas coming from the tube. Use a 
long splinter and stand off about two feet from the bottle to avoid any 
accident that might possibly occur. Do not let acids drop upon the 
clothing or the hands. 
3. Hold a vial over the flame formed in experiment 2 and note the 
water forming on the glass. Explain. 
4. Ask one of the pupils to secure the roots of a clover, bean, or pea 
plant growing in loose soil. After it is washed, let him show in class 
the swellings or tubercles produced by the growth of bacteria taking 
nitrogen from the air. V. FOOD AND ITS USES 
Need of Food. - Food is required to replace dying parts 
and to furnish heat and energy. The weight of a boy 
after taking part in a game of football, or other vigorous 
exercise, during which no water or food has been taken, 
will be several ounces less than before the play ; but in 
the same period the weight of the boy who sat quietly and 
watched the game will show almost no decrease. This 
shows that the muscles wear out by use. Some of the 
worn-out parts pass off in the sweat and breath. The 
temperature of the body is the same in both cold and warm 
weather. This shows that material is being burned inside 
of it to produce heat. Food must therefore be supplied 
to replace what is burned up to keep the body warm. 
Kinds of Foods. - The term food includes everything 
that is consumed for the purpose of nourishing the body 
or supplying it with heat and energy. The five chief food 
stuffs, or proximate principles, are mineral salts, water, pro- 
teids, fats, carbohydrates. All these substances except 
either carbohydrates or fats are absolutely necessary to 
maintain the body in health. Proteids serve to replace 
dying particles of tissues. As both the carbohydrates and 
fats are used largely for furnishing heat and energy, either 
one may be dispensed with, provided an extra supply of 
the other is used. 
Mineral Salts and Water. - These are necessary for 
35 36 
FOOD AND ITS USES 
the proper nourishment of the body. A little common 
salt is present in all meat, but to make it palatable, more 
is usually added. The salts of potash, lime, and iron are 
present in many vegetables and fruits. Dr. Forster fed 
dogs with food from which all the salt had been extracted, 
and as a result they died in about one month. An adult 
takes daily with his food about as much table salt as can 
be held on a large tablespoon. Lime salts are especially 
necessary in the young to help build the bones. Iron salts 
are constantly needed to form an important part of the 
red blood corpuscles. 
Water is a carrier of the foods through the body and 
an aid to the organs in performing their functions. More 
than half of most foods consists of water. 
Proteids. - The white of egg is composed of water and 
albumin, which is one of the commonest forms of proteid. 
Lean beef is made almost entirely' of proteid and water. 
Skim-milk cheese consists of nearly one third proteid and 
two thirds water. Proteids form a part of every cell in 
all plants and animals. 
Heating a proteid or adding to it either alcohol or ni- 
tric acid usually causes it to coagulate, that is, form a 
tough, jellylike mass similar to the boiled white of egg. 
The proteid part of food keeps the tissues of the body in 
repair. If more proteid is eaten than is necessary to re- 
build the worn-out part of the machine, it may be trans- 
formed into fat and may also provide heat and energy by 
becoming oxidized. 
Carbohydrates. - Sugar and starch are nearly pure carbo- 
hydrates. Starch, which occurs abundantly in most vege- 
table foods, is the source from which the body derives STIMULANTS 
37 
nearly all its carbohydrate materials. More than half of 
wheat bread, dried peas, beans, and corn consists of 
carbohydrates, and more than three fourths of wheat flour 
and rice is made of carbohydrates. Meat contains almost no 
carbohydrate material, and eggs none whatever. Carbo- 
hydrates furnish most of the energy of the body and 
some heat. When eaten in large quantities, they tend 
to make a person fat. 
Fats. - Fat occurs in most animal foods. Butter is the 
kind of fat present in milk. Cream cheese is nearly one 
third fat, and eggs about one eighth fat. The fats ex- 
tracted from plants are often called oils. Such are cotton- 
seed oil, linseed oil, and castor oil. Very little fat is 
present in most vegetable foods. Fat eaten and taken to 
the tissues is made to unite with oxygen received Into the 
blood from the lungs, and by this union heat Is pro- 
duced.- The consumption of more fat than the body 
needs may cause one to become fat. 
Condiments and Flavors. - Pepper, salt, vanilla, cinna- 
mon, nutmeg, vinegar, and mustard are called condiments, 
or flavors. They are generally added for the purpose of 
making food more appetizing. The pleasant odors and 
spicy tastes increase the flow of the digestive juices, and 
in that way aid digestion and so increase the real value of 
the food eaten. Too much of the condiments, especially 
pepper vinegar, and mustard, may have an unwholesome 
effect on the cells of the stomach and some of the other 
organs. 
Stimulants. - Tea, coffee, cocoa, chocolate, beef tea, and 
alcoholic drinks are called stimulants because sometimes 
they hasten the action of certain organs. They are all dis- 38 
FOOD AND ITS USES 
cussed in a later chapter, with the exception of beef tea. 
This contains very little nourishment, but is of great value 
in setting the digestive glands to work, and thus preparing 
for the true food which should follow later. The use of 
much beef tea is harmful. 
There is a dispute as to whether alcohol is really a food. 
Whether a food or not, there is danger in using it, owing 
to the fact that many thousands yearly acquire an alcohol 
thirst which causes much ill health and many untimely 
deaths. The Harveian Society has shown that one seventh 
of the deaths of adults in London are due to alcoholic 
drink. Numerous experiments and observations made by 
business men and scientists prove that alcoholic drinks, 
such as beer, whisky, and wine, form the greatest single 
factor in the making of criminals and paupers in this 
country. 
Food Values. -The real value of food does not depend 
upon the amount eaten but upon how much is digested 
and carried from the alimentary canal into the tissues of 
the body. Food has two kinds of value: a tissue value 
and a fuel value. Proteids, 
such as lean meat and skim 
milk, have largely a tissue 
value because they can be 
used in building up the 
parts of the cells and tis- 
sues being worn out. 
Sugars, fats, and starches 
have a large fuel value 
because they unite with oxygen in the body and 
produce heat, muscular movement, and activity of the 
Fig. 21. - Heat-making power of food. 
a, amount of fat required to make 
one calorie or heat unit; b, quantity 
of sugar or pure proteid necessary 
to produce one calorie. AMOUNT OF FOOD NEEDED 
39 
organs. The fuel value is reckoned in heat units. Ex- 
periments show that food burned outside of the body gives 
off the same quantity of heat as when oxidized, or burned 
by the living cells in the body. 
Amount of Food Needed. - Most people eat too much 
of one kind of food, such as meat or sweets. No one can 
live on sugar and fat alone longer than a few weeks, because 
Cornmeal- 
2 lbs. 
I5cts. J 
Beef sirloin, Ji lbs. [ 
54cts. | 
Codfish, 5 lbs. I/Ocents 
Fig. 22. - Diagram showing the difference in cost of three foods each of 
which furnishes about the same amount of nourishment. 
these substances have no tissue value and cannot rebuild 
the worn-out cells. They have only a fuel value, giving 
heat and energy. 
A man at hard labor needs much more fats and 
starches as fuel to furnish energy than one who is idle. 
Experiments on hundreds of persons show that the 
average man should have daily food containing one 
eighth of a pound of pure proteid for the tissues, and 
there should also be fats and starches to furnish a fuel 40 
FOOD AND ITS USES 
value of 3000 heat units. A woman needs about one fifth 
less. To select food with the proper fuel and tissue value, 
one must know of what certain meats and vegetables are 
composed. 
Diet. - Diet is a course of food selected with reference 
to health. A knowledge of diet is important not only 
because it enables one with a small amount of money to 
select the most suitable fare, but because a proper diet 
does much in preventing sickness and in helping the sick 
to get well. 
Recent studies have shown that if the proper attention 
were given to the tissue and fuel value of food, the people 
of this country could purchase the same amount of nour- 
ishment as they now take for $500,000,000 less annually 
than the present cost. 
In some institutions of learning where the average price 
of board is eight dollars per week, the boys anxious to 
economize have been known to board themselves in their 
room at a cost of about three dollars per week. The 
daily fare generally consisted of one quart of milk, some 
fruit, and sufficient bread and oatmeal to satisfy the appe- 
tite. These foods are rich in proteid and have a large 
fuel value. 
Oysters, fish, and beef sirloin are expensive foods. Skim 
milk, potatoes, oatmeal, wheat bread, and corn mush are 
cheap foods that furnish the necessary nourishment. The 
table on the following page (Fig. 23) shows that twenty- 
five cents' worth of corn meal contains nearly five times 
as much proteid and has ten times as much fuel value as 
twenty-five cents' worth of beef sirloin. 
In sickness the diet is more important than medicine. DIET 
41 
25 CENTS 
WORTH OF 
PURCHASE 
PRICE 
OUNCES OF PROTEID 
HEAT UNITS OF FUEL VALUE 
1 
2 
314 
5 
6 
1000 
2000 
3000 
4000 
5000 
6000 
7000 
Beef, round 
39* per lb. 
Beef, sirloin 
47* " " 
- 
Beef, shoulder 
30* " " 
■■I III 
Mutton, leg 
38* " " 
-■ 
Pork, loin 
30* " " 
Pork, salt, fat 
22* " " 
Ham, smoked 
45* " " 
-■ 
Codfish dressed 
29* " " 
Oysters 
70* " qt. 
Milk 
16* " 
Butter 
60* " lb. 
Cheese, cream 
60* " " 
Eggs 
70* " dz. 
Wheat bread 
9* " lb. 
Corn meal 
7* " " 
- 
- 
Oat meal 
Beans, dried 
8 * " " 
11* " " 
Rice 
10* " " 
Potatoes 
3*" " 
Sugar 
9* " " 
TABLE SHOWING HOW TO GET THE MOST FOOD FOR 25 CENTS 
FIG. 23. TABLE OF FOOD VALUES. 42 
FOOD AND ITS USES 
The recovery from dyspepsia, typhoid fever, tuberculosis, 
and all bowel troubles depends largely upon the diet of 
the patient. Constipation, or clogging of the large intes- 
tine, and appendicitis, sometimes resulting from it, may be 
avoided in many cases by choosing a diet from such food^ 
as corn-meal mush, bread from whole wheat, dried and 
fresh fruits, rhubarb, onions, tomatoes, peas, beets, spinach, 
liver, and wild game. Much water should also be taken. 
Hot bread, crackers, pastry, cake, dried and smoked 
meats, cheese, boiled milk, tea, potatoes, and rice should 
seldom be eaten by one troubled with constipation. 
It is said that Germany owed her success in the Franco- 
Prussian War to diet. The disease of beriberi, once so 
common in the Japanese army, was held in check by using 
certain foods and avoiding others. Scurvy, so prevalent 
among the sailors and explorers years ago, now seldom 
occurs because more vegetables and less dried and salt 
meats are used. 
Fruits. - Most fruits contain a large percentage of water 
and only a small amount of the food elements. However, 
they form a very important part of the diet because of 
their agreeable flavor, which increases the flow of the 
digestive juices, helping in the digestion of the other foods. 
They aid much in stimulating in a healthy way the activity 
of the digestive organs, which otherwise may become slug- 
gish and then be harmed by the careless use of pills or 
other drugs. Ripe fruits also furnish some of the mineral 
foods. Overripe fruit and unripe fruit should never be 
used. 
Adulteration of Foods. - A food is said to be adulter- 
ated when a cheaper material is mixed with it or some SPECIAL FOODS 
43 
chemical is employed to preserve it. Alum is sometimes 
added to wheat flour to increase the whiteness. Wheat 
flour, gypsum, clay, and radish seeds are often present in 
prepared mustard. Ground corn, rice, buckwheat hulls, 
cocoanut shells, crushed olive stones, and sawdust are 
frequent adulterants of pepper. Coffee is occasionally 
adulterated with the ground-up root of the chicory plant. 
Olive oil sometimes contains large quantities of cotton- 
seed and peanut oils. Milk is frequently diluted with 
water. 
Of 8651 samples of food examined in Massachusetts in 
1904, over twenty-six per cent was found to be adulterated. 
As only those foods thought to of poor quality were 
selected, it is probable that the actual proportion of adulter- 
ated foods in the market is much less. The recently 
enacted pure food laws and the appointment of inspectors 
are doing much to lessen the sale of impure foods. 
Special Foods. - The breakfast foods which are sold' 
cooked and ready for the table are pure and wholesome, 
as most of them are made from steamed and crushed 
wheat, oats, or corn. For nourishment, well-cooked oat- 
meal is equal to them, is much cheaper, and is quite as 
palatable when mixed with a few chopped dates, figs, or 
bananas. 
Renovated butter, made by purifying a rancid or poor 
quality of butter, is sold at a lower price than genuine 
butter, but contains about the same food value. Butterine 
and oleomargarine, of which 70,000,000 pounds are sold 
yearly, are made from tallow, lard, cottonseed oil, and 
cream. They are good foods, but are not worth so much 
as butter. Fruits, vegetables, and meats put up in cans 44 
FOOD AND ITS USES 
are usually wholesome, but it is preferable to use the fresh 
articles when they can be obtained. 
Cooking. -■ Foods are cooked for three purposes: to ren- 
der them more easily digestible, to develop the flavors, and 
to kill the germs of disease which occasionally may be pres- 
ent. Meats are most healthful when baked, roasted, boiled, 
or broiled. To boil meats and vegetables, they should be 
at the first immersed in boiling water to coagulate the sur- 
face layer, and thus prevent the escape of the nourishment. 
In making stews and soups, the meat and vegetables 
should be put into cold water and slowly heated to near 
the boiling point. In this way the water draws out the 
flavors and nourishment to form delicious soup. Old 
bread and toasted bread are much more easily digested 
than that newly baked. Fried foods often cause indi- 
gestion. 
Hard-boiled eggs are not so easily digested as those par- 
tially cooked. A good method of preparing eggs for the 
table is to put them in a pan off the stove and pour on 
sufficient boiling water to cover them one inch deep. In 
fifteen or twenty minutes the white will be in a creamy 
state easy to digest, and the yolk will also be well cooked, 
but not hard. Eggs thus cooked are easily digested by 
invalids and year-old children. 
To cook food so that it shall be highly nutritious and 
delicious, is an art which every girl ought to acquire. 
Poorly cooked food causes ill temper, ill health, and un- 
happiness. The dry and insipid bread often bought at the 
store or bakery should not replace the appetizing home- 
made article. The girl who knows how to prepare a 
dainty meal and serve it with a pleasant smile is sunshine SUGGESTIONS FOR THE TEACHER 
45 
in any home. The boys who obtain the greatest profit 
and pleasure from camping know how to cook. 
Questions 
1. What is a food? 2. Which of the food stuffs are necessary to life ? 
3. Where do proteids occur ? 4. What foods contain much carbohy- 
drate? 5. Mention a food containing no carbohydrate. 6. Name 
several kinds of fats. 7. What is the effect in some cases of eating 
much fat and carbohydrates ? 8. What evidence can you give show- 
ing that some mineral salts are necessary for health ? 9. How much 
water does a man take into his body daily? 10. Which of the condi- 
ments may harm the system? 11. What are stimulants? 12. Give 
three reasons why alcoholic drinks should not be used. 13. What two 
kinds of value has food? 14. How does food keep the body warm ? 
15. How much food does an average man need daily ? 16. Explain 
why five cents' worth of corn meal is of more value as a food than 
twenty-five cents' worth of sirloin. 17. Show that five cents' worth 
of oatmeal has as much food value as twenty-five cents' worth of 
mutton leg. 18. Why is ten cents' worth of beans equal in food value 
to a dollar's worth of oysters? 19. Of what importance is diet in 
sickness? 20. Describe renovated butter, butterine, and oleomar- 
garine. 
I 
Suggestions for the Teacher 
1. Ask a pupil to weigh a peeled apple, and after drying it in the 
oven a day or two, to weigh it again. Request another pupil to do 
the same with a potato. Calculate what part of these foods is 
water. 
2. Ask several of the pupils to try cooking eggs at home so that 
the yolk may be made palatable and yet the white remain like a tnick 
cream instead of being rendered hard and tough. VI. MICROBES AND MOLDS 
The Ancient Belief as to the Origin of Life. - Until the 
middle of the last century, people generally believed in what 
is known as spontaneous generation. This is the changing 
of dead particles of matter into living forms without the 
aid of any other life. Aristotle said over 2000 years ago 
that some animals spring from putrid matter, certain in- 
sects come from dew, threadworms originate in the mud 
of wells, and lice proceed from the flesh of other creatures. 
Even to-day some people believe that the maggots, or little 
wormlike animals found on meat in warm 
weather, have come from the meat. The 
fact is that the maggots result from the 
hatching of the eggs of flies which were 
laid on the meat. 
If flies are kept away from meat in 
warm weather by netting, it will nevertheless spoil. The 
microscope shows that the spoiling is due to millions of 
tiny plants now called bacteria. 
Discovery of the Cause of the spoiling of Food. - Milk 
or meat broth standing exposed a day or two in warm 
weather begins to decay. In it are formed great numbers 
of bacteria which until forty years ago were thought by 
many to be particles of the milk or broth changed to life 
by spontaneous generation. Tyndall, Pasteur, and others 
have shown that the bacteria came from the growth of 
Fig. 24. - Bacteria 
that cause meat 
to spoil. Magni- 
fied. 
46 THE NATURE OF BACTERIA 
47 
other bacteria always found floating in the air. This was 
proved by placing some broth in several jars, some of which, 
after being boiled to kill all life, were tightly sealed, while 
the others were left open. In a few days all of those re- 
maining open were found to contain numerous tiny living 
Fig. 25. - Mold growing on bread. The little knobs on the top of some 
of the threads contain hundreds of tiny round bodies called spores or 
germs. 1'hese break loose and being blown about get on food and cause 
another growth of mold. 
and moving bodies. Even after weeks the sealed jars con- 
tained no life. 
The Nature of Bacteria. - Bacteria are one-celled plants. 
They are often called microbes or germs. Minute one-celled 
animals are also called microbes or germs. A piece of mold 
is sometimes spoken of as a germ. Molds differ from bac- 
teria in being much larger, forming long threads, and not 
dividing in the middle to produce new plants. Some molds 
are useful in giving flavor to cheese, others cause decay in 
any vegetable or animal material on which they grow, and 48 
MICROBES AND MOLDS 
a few kinds may produce disease, such as ringworm and 
barber's itch. 
Over 1000 different kinds of bacteria are now known, 
but it is impossible, except in a few cases, to distinguish 
one kind from 
another by merely 
examining them 
with the micro- 
scope, because 
several different 
varieties have ex- 
actly the same 
shape. There are 
three general 
forms: the spheri- 
cal ones, named 
cocci; the rodlike, 
known as bacilli; 
and the curved 
ones, called spi- 
rilla. The bacilli 
are the most com- 
mon forms, but the spirilla are the largest, some of them 
in stagnant water being easily seen under a microscope 
magnifying only 100 diameters. 
Bacteria are abundant in milk, water, soil, and air. A 
bit of rich earth as large as a pea may contain over 
5,000,000. The usual water often consumed in one drink 
contains more than 50,000, and a glass of good buttermilk 
has in it millions of bacteria. Vast numbers live on 
the surface of the body, and millions dwell in the alimen- 
Fig. 26. - This flat cell, having on its surface over 
200 bacteria, is from the mouth of a well person. 
Thousands of such cells with bacteria are present 
in all mouths. Photographed through a micro- 
scope. BACTERIA AND DISEASE 
49 
tary canal, while still others are being blown about in the 
air. When the air is quiet, they settle down and stick 
fast on all moist surfaces. Most bacteria are harmless to 
man when taken into the nose or stomach. A few kinds 
produce disease, and some others are of great use in 
nature. 
How Bacteria grow and Multiply. - With favorable sur- 
roundings, such as warmth, moisture, and food, bacteria 
increase rapidly in num- 
bers. Their method of 
growth is to lengthen 
out slightly and then to 
divide crosswise into two equal parts. A germ can divide 
every half hour so that one plant might produce many 
millions of descendants in one day. Most of them can 
live for months in a dry state, and some can remain alive 
all winter in a cake of ice. Certain kinds are able, when 
food fails, to surround a portion of their living material 
with a thick, protecting coat, and thus form a spore (Fig. 
28). The spores of some germs may be boiled over 
twenty minutes without killing them. Fortunately none 
of our common disease-producing bacteria can 
form spores, and they are therefore easily 
killed by heat. 
Bacteria and Disease. - Only about thirty 
different kinds of bacteria produce disease in 
man. Diseases caused by germs are known 
as infectious diseases because the germ infects 
or makes its way into the body. Bacillus 
tuberculosis causes consumption, scrofula, and white swell- 
ing. The diphtheria bacilli, growing in the throat, produce 
Fig. 27.-Diagram showing how bacteria 
divide to form new bacteria. 
Fig. 28. - Bac- 
teria, four of 
which contain 
spores. 
D*V. PHYS. 4 50 
MICROBES AND MOLDS 
diphtheria. Pneumonia, sore throat, and colds occur 
when certain bacteria are present in great numbers. 
Whether disease-producing bacteria, after gaining en- 
trance to the body, shall cause disease or not, depends upon 
the ability of the tissues 
to destroy them. 
How Bacteria produce 
Disease. - Bacteria must 
get into the tissues and 
multiply in order to cause 
disease. They may find 
entrance through the ali- 
mentary canal, the lungs, 
or the skin. Germs like 
those of tuberculosis and 
typhoid fever may reach 
the intestine with food or 
water, and penetrate the 
cells there, and even pass 
through the walls of the 
intestine into the blood 
to be carried to any part 
of the body. Throwing 
dead animals or waste matter into a stream of water is a 
crime, because the bacteria in them may cause disease and 
death to persons living along the stream and using the 
water for drinking. With the air, bacteria enter the 
lungs when some of the ciliated cells lining the air tubes 
are injured. A break in the skin or even a faulty skin 
gland may permit bacteria to reach the tissues beneath 
and produce a running sore; or blood poison may result 
Fig. 29. - Germs that cause tuberculosis 
or consumption growing in clusters ap- 
pearing as w'hite spots on a piece of 
potato smeared with glycerine. THE USEFUL BACTERIA 
51 
if they are carried through the system. Knives, needles, 
and dressings used in any operation, such as removing 
a splinter, or vaccination, should first be 
boiled to kill the germs on them. 
Bacteria injure the body in two ways. 
They consume the tissue, and they give 
off poisons. The bacteria causing boils 
eat away the tissues so as to form little 
holes, but they do not give off much 
poison. The diphtheria bacilli do not destroy much 
tissue, but excrete a great deal of poison, affecting the 
heart and other organs. 
The Useful Bacteria. - The souring of 
cream for churning, the flavor of some 
cheese, the manufacture of linen, the 
making of vinegar, and the fertility of 
the soil depend upon different groups of 
bacteria. The action produced by bac- 
teria on any substance is known as fermentation. The 
cider by means of yeast always present on fruit is fer- 
mented to form a weak alcohol, 
and then certain bacteria by fer- 
mentation change the alcohol to 
vinegar. 
Straw, hay, and the bodies of 
dead animals cannot decay without 
bacteria. This decay is absolutely 
necessary before dead material can 
become food for the green plants. 
If there were no bacteria to rot waste matter and thus 
fertilize the soil, the plants would soon use up all the 
Fig. 30. - Bacteria 
that cause boils. 
Maguified. 
Fig. 31. - Bacteria 
that cause milk to 
sour. Magnified. 
Fig. 32. - Plants that cause 
fermentation, a, yeast 
plants which change cider 
partly to alcohol; b, bac- 
teria which change the 
alcohol to vinegar. 52 
MICROBES AND MOLDS 
nourishment in the ground and die. The animals would 
then have no food, and their death must result, and man 
would follow the same fate. It is evident, therefore, that 
this world is saved from becoming a dreary waste by the 
action of tiny bacteria. 
The Preserving of Food. - Since intense cold prevents 
the growth of bacteria and molds, foods are put in ice 
houses and refrigerators to prevent spoiling. Meat at 
freezing temperature may be preserved for years. Some 
meats, such as smoked ham and dried beef, have been 
soaked in a salt solution several weeks or well rubbed 
with salt, and then smoked and dried on the surface. 
This keeps out the bacteria, and the salt restrains greatly 
the growth of bacteria and molds. 
Fruits and vegetables are heated to kill the germs and 
then sealed up tight in cans. Even then mold often 
grows on top of the food in the can because the lid and 
can were not kept in boiling water the ten minutes nec- 
essary to kill the spores of mold. The best plan in 
canning food is to put it into the jars and then cook it 
by placing the filled jars with the covers screwed on 
loosely in the oven or in a wash boiler on top of the 
stove. If the boiler is used, an inch or more of water and 
a cloth to prevent breakage must be put in the bottom. 
The occasional poisoning resulting from the use of 
canned fish or meat is due to bacteria which were not 
killed in the cooking. They grow and form a poison 
called ptomaine. Sickness from cold-storage food is often 
due to the meat-poisoning bacillus which grows and gives 
off a poison after reaching the intestine. Food should 
never remain in a metal can after it has been once opened. SUGGESTIONS FOR THE TEACHER 
53 
Eggs may be preserved in a good condition for a period 
of about five months by immersing them in a tin or stone jar 
or wooden keg of dilute soluble glass (silicate of sodium). 
The pure soluble glass may be purchased at the drug store. 
The dilute soluble glass is made by adding one quart of 
pure soluble glass to ten quarts of water. 
Questions 
1. What did the ancients believe as to the origin of life? 2. flow 
was the cause of the spoiling of food discovered ? 3. flow do molds 
differ from bacteria? 4. Where are bacteria found and how numer- 
ous are they ? 5. About how many bacteria are required to make a mass 
as large as the head of a pm ? 6. How rapidly do bacteria multiply ? 
7. What proves that bacteria can endure severe cold and heat ? 
8. Name some diseases due to bacteria. 9. How may bacteria get into 
the body? 10. How do bacteria injure the body? 11. Of what use 
are bacteria to the fruit and dairy industries ? 12. Why could not life 
continue to exist without the aid of bacteria? 13. What prevents 
bacteria from destroying food? 14. How may the housekeeper pre- 
vent mold from growing on her canned fruit ? 15. Why do canned 
meats occasionally poison people ? 
Suggestions for the Teacher 
1. Moisten well some bread and then touch it to the floor in a few 
places to get the spores or germs of mold. Place in a tightly covered 
bowl in a warm room, and observe in from three to six days the 
threadlike growth of mold on the surface of the bread and erect 
branches bearing at their ends knobs which contain spores. 
2. Colonies or groups of bacteria may be secured as follows: Ask 
several of the pupils to boil a potato a half hour, and then cut it into 
halves with a knife cleaned in boiling water. Stand each half in a 
cup containing about a spoonful of water. Set the cups in a room 
being swept for a minute or two, and then cover with a saucer tightly 
and keep in a warm room about a week. Note the white and yellow 
slimy spots which are colonies or clusters of bacteria produced wher- 
ever a single germ fell. VII. MILK 
Why a Knowledge of Milk is Important. - Milk forms 
the greater part of the food of every individual during 
the first year of life, and is often the chief nourishment 
for invalids. Nearly all of the thousands of patients now 
recovering from tuberculosis are using from one to three 
quarts of milk daily. A recent circular of the State Board 
of Health of New Jersey says: "The 
most important element in the enormous 
saving of child life, which is now occur- 
ring, consists in a better understanding 
of the dangers attending the use of 
unclean milk." 
Professor Sedgwick, a leading sani- 
tarian, says: " Among all the vehicles 
of infectious disease there is perhaps 
„ none more dangerous than milk." The 
Fig. 33. - Diagram of & 
a bottle of milk, United States Census and Health Re- 
showmg of what it pOrts spow that 50,000 children under 
is composed. x 
five years of age died from the use of 
unclean milk during the years 1900-1904. Many other 
children, as well as adults, were made sick by the use 
of milk handled in a careless way. 
Composition. - Cow's milk contains all five kinds of 
food stuffs. It consists of 87 parts of water, 4 parts of 
proteids, 4^ parts of carbohydrates, 3| parts of fats, and 
Mat 
^ugar 
^protetd 
^Xminerali 
water 
54 FOOD VALUE 
55 
| part of mineral matter. The chief proteid of milk is 
casein, which is coagulated into a jellylike mass called 
curd when milk becomes sour. The fat is in the form 
of minute globules two or three thousand of which are 
required to make a piece of butter as large as a pin 
head. The carbohydrate is milk 
sugar, much used by druggists in 
making pills. The most important 
of the several minerals in milk is 
lime. 
Food Value. - Milk is the only 
single article of food that contains 
all the elements necessary to the 
growth of the body. It is a perfect 
food, however, only for the very 
young, as the substances required 
for nourishing the adult are not 
present in the right proportions. 
Since cow's milk is quite different 
in composition from human milk, 
water, cream, and sugar are usually 
added to it when it is to be used 
for infants. 
It would require about one gallon 
of milk daily to furnish a working- 
man the necessary amount of tissue-repairing substance, 
but the fats and sugars would not be sufficient to give 
the required heat and energy. Milk combined with 
bread and potatoes makes a diet enabling men to perform 
the heaviest work. A quart of milk contains the same 
amount of nourishment as three fourths of a pound of 
Fig. 34.- A quart of milk 
and a chicken weighing 
about one pound. The 
chicken furnishes the 
same nourishment for 
the body as the milk, 
but costs four times as 
much. 56 
MILK 
beef. Milk surpasses many foods in real nourishing 
value not only because it contains more nutrition, but 
also because it is almost completely digested and ab- 
sorbed, whereas from one tenth 
to one fourth of some vegetables 
consumed remain undigested. 
Economy in using Milk. - 
Milk, at six cents per quart, 
forms a cheap nourishment 
when used with other foods, 
at the rate of one quart per day. 
An ordinary restaurant lunch 
of soup, beef, potatoes, turnips, 
bread, butter, and coffee, cost- 
ing fifty cents, will furnish 
no more nutrition than a dairy 
lunch consisting of a half loaf 
of bread and a pint of skim 
milk, costing five cents. 
A pound of sirloin steak, 
costing twenty cents, contains 
about the same amount of 
tissue builder as two quarts 
of milk, costing twelve cents, but the meat has only two 
thirds of the fuel value of the milk. 
Skim Milk. - When milk is allowed to remain undis- 
turbed in a vessel for several hours, much of the cream, 
containing the fat, rises to the top and may be removed. 
The fluid left is called skim milk. It contains the same 
nutriment as whole milk except the fat, which is dimin- 
ished from three fourths to nine tenths. Skim milk is 
Fig. 35. - A bottle of very sour 
milk (photographed), showing 
what it consists of. After 
Swithenbank and Newman. CREAM 
57 
therefore an excellent food, as it contains much proteid 
for tissue building and considerable sugar for fuel value. 
Two and a half quarts of skim milk have the same food 
value as a pound of the best lean beef. Two quarts of 
skim milk, costing six or eight cents, contain more nour- 
ishment than a quart of oysters, costing forty or fifty cents. 
Fig. 36. - Globules of fat in skim milk, milk, and cream, as seen through the 
microscope. 
About one tenth of skim milk is composed of solids 
which have all the value of whole milk for making blood, 
muscles, and bones, but only half the fuel value. 
Buttermilk is soured milk from which the fat globules 
have been removed after being collected by churning into 
large masses called butter. Butter milk contains about 
the same nutriment as skim milk. As a food for calves 
and pigs it is worth at least one cent per quart. 
Cream. - About one sixth part of milk consists of cream, 
which rises to the top when a vessel of fresh milk is let 
stand a few hours. It is formed of fine globules of 58 
MILK 
fat with some milk entangled among them. Cream con- 
tains less muscle-building substance than skim milk, but 
is of great value in the treatment and cure of consump- 
tion. It costs less than cod-liver oil, and is quite as effec- 
tive in the treatment of 
all forms of tuberculosis. 
Condensed Milk.- 
This is cow's milk which 
has been heated to kill 
the germs and to evapo- 
rate about two thirds of 
the water. Sugar is 
often added to prevent the growth of any germs remain- 
ing. Some condensed milk is made from skim milk. 
Condensed milk should not be used regularly for feeding 
infants. 
Souring of Milk. - The souring of milk is caused by 
bacteria. They are everywhere present in the air, on the 
cow, on the hands, and in the unclean milk pail. Most of 
them, when in milk not kept cold, grow very rapidly and 
change part of the milk sugar into an acid. Milk in a 
pail surrounded by ice may remain sweet a week, but 
if left in the warm living room will turn sour in a day< 
When milk becomes sour, there are usually about 250,000 
bacteria in each drop. 
Bacteria in Milk. - All milk sold contains bacteria. The 
number in each drop usually varies from 500 to 90,000. 
They are generally harmless to health. The milk while 
in the udder of healthy cows contains no bacteria, but 
thousands are present in the lower part of the canal of 
each teat. The first two or three squirts of milk, there- 
Fig. 37. - A tiny drop of milk prepared for 
examination with the microscope, g, glass 
slide; m, milk; c, thin piece of glass over 
the milk. BACTERIA IN MILK 
59 
fore, washes out hundreds of them. The milk pail is 
another source of bacteria. Wooden buckets cannot be 
kept clean and should never be used. A metal pail, 
rinsed with hot water and hung upside down, will in most 
cases after twelve hours contain more than a million bac- 
teria. A single hair falling 
from the cow into the pail 
has been shown to have on it 
over 1000 bacteria, and every 
little particle of dirt brushed 
off from the udder adds from 
a hundred to several thousand 
germs to the milk. Others 
come from the unclean hands 
of the milker. The throwing 
down of hay or the kicking 
about of dry straw has been 
shown to fill the air with bacteria to such an extent 
that over 3000 per minute fell into the open milk pail. 
Milk immediately after being drawn from the cow 
usually contains from 200 to 2000 germs in every drop, 
depending upon the cleanliness of the milker, the cow, 
the pail, and the stable. Feeding the cows dry hay or 
cleaning the stables just before or during milking will 
quadruple the number of germs in the milk. Persons 
neglecting to wash the hands thoroughly before milking 
may infect the milk with the germs of scarlet fever, ton- 
silitis, diphtheria, or typhoid fever. The following table 
gives clear evidence that in warm milk the bacteria grow 
nearly a million times as fast as in milk kept in a cool 
cellar or in cold spring water. 
Fig. 38. - Drawing of the bacteria, 
in the milk within the tiny circle 
shown in Figure 37, as seen 
through the microscope. 60 
MILK 
Development of Bacteria in a Drop of Milk 
Bacteria in 
Fresh Milk 
After 9 Hr. 
After 24 Hr. 
After 48 Hr. 
Temperature at 
which Milk was 
Kept 
1500 
250,000 
1,000,000,000 
unknown 
summer heat, 94° 
1500 
30,000 
200,000 
1,000,000,000 
living room, 68° 
1500 
3,000 
10,000 
2,000,000 
cool cellar, 55° 
1500 
1,600 
2,000 
16,000 
refrigerator, 45° 
1500 
1,550 
1,600 
2,500 
packed in ice, 35° 
How to produce the Best Milk. - The stable should be 
well lighted and have enough openings to admit plenty of 
fresh air. Except in very severe weather the cows ought 
not to remain in the stables between the milkings, because 
plenty of fresh air prevents tuberculosis. The floors 
should be cemented and kept clean, and the loose hair and 
dirt removed from the cows an hour before each milking. 
The udders can be cleaned with a damp cloth. Only tin 
or agate pails, washed with cold water and then with 
boiling water and soda, are to be used. Neither a cloth 
nor the hands should touch the inside of a milk receptacle 
after it has been rinsed well with boiling water. The 
milker should wash his hands thoroughly just before 
milking. Bacteria and dirt may be still further excluded 
by laying a piece of cheese cloth across the mouth of the 
pail and milking through it. Milk thus produced brings 
from ten to fifteen cents per quart in the market, and will 
make the highest quality of butter. 
Care of Milk. - Although most of the market milk con- 
tains nearly 10,000 bacteria in each drop, milk produced 
in the way described above, and cared for properly, 
should be CARE OF MILK 
61 
contains only from 100 to 180 bacteria per drop. Such milk 
will remain sweet four days in an ordinary cellar during 
J uly. The certified milk which is approved by medical soci- 
eties in cities usually 
contains less than 500 
germs per drop and 
no bacteria which 
will produce disease. 
Straining the milk 
immediately after 
milking, through one 
or two thicknesses of 
cheese cloth and a 
thin layer of absorb- 
ent cotton, will re- 
move the finest par- 
ticles of dirt and 
many bacteria. It 
is said that 300 
pounds of dirt are 
consumed daily in 
the milk supplied to 
New York. As soon 
as strained, the milk should be cooled by means of a 
patent cooler or by placing the cans in cold water and 
stirring several times for a few minutes. It should 
then be kept in a clean cold room free from flies and all 
odors. 
Milk ought to be sent to market in glass bottles sealed 
with paraffined pieces of pasteboard. The thousands of 
germs carried on the feet of flies and blown with the dust 
Fig. 39. - A dish with a thin layer of beef broth 
jelly, in which most bacteria will grow. A fly 
was allowed to walk around on the jelly a 
few minutes, and wherever it left a germ from 
its feet it grew to form a cluster or colony of 
germs within a day or two. Each white spot 
is a colony containing millions of bacteria 
which would have grown in much the same 
way if the fly had carried them into the milk. 62 
MILK 
into the milkman's measure are then avoided. Many 
of these germs come from spittoons and the filth in 
gutters. I have found as many as 800 bacteria per 
minute falling upon an area equal to the opening into 
an ordinary milk measure. Cream rises quickly on milk, 
and unless it is bottled as soon as milked, one customer 
will receive more and another less than the correct pro- 
portion of cream. 
Adulteration. - Before the enactment of the pure food 
laws and the appointment of inspectors, a considerable 
amount of the milk in every town and city was adul- 
terated with water, and had added to it chemicals to 
make it remain sweet. It is a crime to add anything 
whatever to milk. Every town should have an in- 
spector to see that sickness and death do not occur on 
account of impure milk. It is responsible for much of the 
cholera infantum and other bowel troubles of children. 
In Rochester, from 1891 to 1896, when no special effort 
was made by the city to maintain a pure milk supply, 
1000 more children died than during the years 1897 to 
1902, when every effort was put forth to secure clean 
milk. Actual experience in the city of Leeds shows 
that among children using pure milk about one fourth less 
die than among those using the ordinary market milk. 
Diseases conveyed by Milk. - Careful investigations by 
more than a hundred men prove clearly that sore throat, 
cholera infantum, typhoid fever, scarlet fever, diphtheria, 
and tuberculosis have been in many cases transmitted by 
means of milk. The germs of all of these diseases except 
tuberculosis and perhaps scarlet fever grow rapidly in 
milk not too cold. It has been shown that a single germ TYPHOID FEVER AND MILK 
63 
of diphtheria dropped from the lips or hands into milk, 
can in twelve hours produce over 100,000 of its kind. 
The cow is not subject to any of these diseases except 
tuberculosis, and therefore the germs of the other dis- 
eases must find their way into the milk from the water, 
the hands, the clothing, 
the dust, or flies. Over 
300 epidemics of infec- 
tious diseases, each af- 
fecting from 10 to 500 
persons, have been caused 
by milk. Dirty cows, 
dirty stables, dirty hands, 
or dirty vessels used in 
the production of milk 
will sooner or later bring 
sickness and in some 
cases death to some of 
those using it. 
Typhoid Fever and Milk. - At Cambridge, Massachu- 
setts, there was a typhoid epidemic affecting 73 persons, 
all of whom had used milk from a farm where the father 
nursed his son sick with the fever and also did the milking. 
At Elkton, Maryland, in 1900, one milkman, whose wife as- 
sisted in caring for a typhoid patient and also did the dairy 
work, supplied 39 families with milk, and in every home 
from one to three members became ill with the fever. 
In 1903, in Palo Alto, California, 236 cases of fever re- 
sulted from the use of milk part of which came from a 
dairy along a stream known to contain typhoid germs. 
These reached the water from patients living on the bank 
Fig. 40. - Drawing of typhoid germs as 
seen through the microscope. 64 
MILK 
three miles above the dairy. The water from the stream 
was used to wash the milk cans. Over 200 epidemics of 
typhoid, each affecting from 10 to 500 persons, have been 
traced to milk as the source. 
Diphtheria and Scarlet Fever in Relation to Milk.- 
Over 100 epidemics of these diseases are known to have 
had their source in the 
milk supply. At Ashta- 
bula a hundred persons 
were infected with diph- 
theria, by germs from one 
dairy where a man with 
a light case of the disease 
helped care for the milk. 
In January and February 
of 1907 the milk of one 
company caused over 600 
cases of scarlet fever in 
Boston and vicinity. 
No one who has suffered 
from any of these dan- 
gerous diseases should 
handle the milk until a month after recovery, because the 
germs sometimes remain several weeks in the system. 
Tuberculosis and Milk. - Many cows have tuberculosis 
in a mild form. Very few herds kept most of the time 
in stables are free from this disease. The recent govern- 
ment reports indicate that over 1,000,000 cows in this 
country have tuberculosis, and some of them are shed- 
ding these germs into the milk, while nearly all tubercu- 
lous cattle give off the germs in their excretions. 
Fig. 41. - Intestine from child having tu- 
berculosis. The half hundred little lumps 
are tubercles full of germs developed 
from a few which the child swallowed. 
Bureau of Animal Industry. PASTEURIZATION 
65 
There is no longer any doubt that children may acquire 
tuberculosis by using the milk of cows afflicted with this 
disease. Twelve girls, having healthy parents, contracted 
tuberculosis in a young ladies' boarding school in Paris. 
Five died, and an examination showed that the disease had 
begun in the intestines. The cow which had furnished 
the girls with milk 
was then suspected 
of being diseased and 
was killed. The milk 
ducts upon being 
opened were found to 
be badly affected 
with tuberculosis. 
Many similar cases 
are now on record. 
In some cities as 
many as 10 in every 100 samples of milk examined con- 
tained the germs of tuberculosis. It is a crime to sell the 
milk from cattle known to be diseased. The only way to 
determine whether a cow has tuberculosis is to have an 
expert use the tuberculin test. 
Pasteurization. - When one is not sure that the milk to 
be given a child or invalid is perfectly fresh and clean, 
and from healthy cows, it is wise to pasteurize it. Pas- 
teurization, so called from Pasteur the inventor, consists 
in heating the milk twenty minutes at about 160° Fah- 
renheit. This renders all disease germs harmless and 
kills most of the souring germs, but does not make the 
milk less easily digestible. Boiling renders the milk a 
little more difficult of digestion by a weak stomach, and 
Fig. 42. - Pasteurizing apparatus. 
DAV. PHYS. 5 66 
MILK 
changes the taste. Pasteurized milk will remain sweet 
twice as long as raw milk. 
The easiest way to pasteurize is to place the milk in a 
quart fruit jar or an agate vessel having the shape of a 
fruit jar. This is then to be set into a vessel of boiling 
water just removed from the stove, and the milk stirred 
with a clean spoon for ten minutes. It must then be 
covered and left fifteen minutes longer in the water, after 
which it should be cooled quickly by placing on ice or in 
cold water. It is necessary that the amount of boiling 
water in the teakettle or other vessel be four or five times 
as much as the milk, and deep enough so that its surface 
will be about on a level with the suiface of the milk in 
the jar. If a glass jar is used, it must be placed on the 
back part of the stove a few minutes until it becomes 
about as warm as the hand to avoid being broken by the 
hot water. Pasteurized milk has saved the lives of many 
infants and invalids. A special pasteurizing apparatus, as 
shown in Figure 42, may be purchased for a small amount. 
Questions 
1. Of what importance is milk ? 2. Give the composition of milk. 
3. What can you say of the food value of milk? 4. By the table on 
page 41 compare the food value of milk and beef. 5. Show that milk 
at ten cents per quart is a cheaper food than eggs at twenty-four cents 
per dozen. 6. Explain the food value of skim milk. 7. What is 
buttermilk ? 8. Of what value is cream ? 9. How is condensed milk 
produced? 10. Why does milk become sour ? 11. What are bacteria? 
12. How do bacteria get into milk ? 13. Explain the effect of tem- 
peratures on the bacteria in milk. 14. Give some directions to be 
observed in producing the best grade of milk. 15. What care should 
be given milk? 16. Why should milk be marketed in bottles? 
17. State some facts about the adulteration of milk. 18. What disease 
germs grow after finding their way into milk ? 19. How may the SUGGESTIONS FOR THE TEACHER 
67 
germs of typhoid fever get into milk? 20. Give facts showing that 
no one caring for patients with diphtheria or scarlet fever should 
handle the market milk. 21. Give evidence showing that persons 
may acquire tuberculosis by drinking milk from tuberculous cows. 
22. How may milk be pasteurized ? 23. What is the benefit of pas- 
teurization? 
Suggestions for the Teacher 
1. Ask the pupils to note whether the milk used at home leaves an 
unpleasant taste in the mouth. Pure milk gives no unpleasant after- 
flavor reminding one of the smell of a cow. Ask the pupils to observe 
whether there is any sediment in the milk pail or bottle after the 
milk has stood several hours and is then carefully poured off. 
2. Ask some of the pupils to put the lid tightly on the milk can 
at night after washing it, and the following morning note the odor, due 
to the fact that the germs were not washed out clean. Babies fed 
milk from such vessels often get cholera infantum or other bowel 
trouble, which frequently results in death. Ask the same pupils to clean 
the milk can the next night by rinsing it well with cold water and 
then washing it out with boiling water and finally scalding it by 
placing it on the stove, with an inch or two of water in it, to boil five 
minutes with the lid on. Note the absence of odor the following 
morning. 
3. If possible, have one of the pupils draw milk from the clean 
udder of a cow into a scalded glass jar, which should be immediately 
placed in a pan of cold water and stirred with a clean spoon ten min- 
utes. Cover and keep cool, noting that it will remain sweet twice as 
long as milk cared for in the ordinary way. VIII. NARCOTICS AND STIMULANTS 
Characteristics. - Narcotics are substances which act on 
the system so as to relieve pain and tend to produce 
sleep. If taken in large doses, they cause a person to 
fall into a kind of a stupor or deep sleep. The com- 
monest narcotics are tobacco, alcohol in large doses, opium, 
morphine, laudanum, paregoric, and many of the patent 
medicines. 
Stimulants are substances which cause any organs of the 
body to act more vigorously than is their custom. Tea 
and coffee are stimulants frequently used. Neither nar- 
cotics or stimulants are necessary to enable an individual 
to make the greatest success in life. Moreover, it is well 
known that persons not accustomed to the excessive use 
of these drugs are much healthier and happier than those 
who are slaves to them. 
Tobacco is a poison. Like other poisons, one may be- 
come so accustomed to its use by beginning with small 
doses and gradually increasing them, that large quantities 
smoked or chewed have but little apparent effect in older 
persons. 
In certain parts of Italy some of the people have become 
so accustomed to the use of arsenic that they take ten 
times as much in a single dose as would be fatal to a 
person not in the habit of eating this poison. 
The active principle in tobacco is nicotine. It is this 
which makes one so sick and sleepy when he for the first 
68 HOW TOBACCO HARMS 
69 
time smokes even an inch of a cigar or takes one or two 
chews of tobacco. Tobacco consists of the dried leaves 
of the tobacco plant grown extensively in the valley of 
the Connecticut River and in Kentucky, West Virginia, 
and many other parts of the South, as well as in the West 
Indies. It cannot be considered a food, but it lessens the 
feeling of hunger by its sleep-producing effect. 
How Tobacco Harms. - If there is an inherited tendency 
to cancer, the irritation of the membranes of the mouth by 
the constant presence of tobacco is likely to cause the dis- 
ease to break out in that place. Catarrh, hoarseness, and 
throat trouble are common among those using tobacco to 
excess. 
While a person is chewing tobacco, the salivary glands 
are kept in a continual state of. activity, so that much 
saliva is lost in spitting. As a result the saliva that flows 
when food enters the mouth is of a poor quality, fails to 
act on the food properly, and then indigestion may be the 
consequence. 
The nicotine absorbed by the vessels in the membrane 
of the mouth has, especially in the young, an injurious 
effect on the heart. About one fourth of all steady 
smokers show an irregular pulse beat. This condition 
has caused a large number of candidates for the United 
States Naval Academy to be rejected. Students in the 
Naval Academy are no longer permitted to use tobacco. 
Alfred A. Woodhull, a surgeon in the United States 
Army, says: "Tobacco degrades the tissues generally, and 
it predisposes to neuralgia, vertigo, indigestion, and other 
disturbances of the nervous, circulatory, and digestive 
systems." 70 
NARCOTICS AND STIMULANTS 
Cigarettes. - Cigarette smoking is the most harmful 
form in which tobacco is used. This is not due to the 
presence of more nicotine or other narcotic drugs. Ciga- 
rettes are especially damaging to health because it is the 
habit of those using them to inhale the smoke. This act 
carries the nicotine down into the air spaces in the lungs. 
Here it is much more readily absorbed than in the mouth. 
The user of cigarettes is also more likely to smoke to ex- 
cess than one addicted to the cigar or the pipe. The use 
of the cigarette makes one more a slave to the drug, so that 
when he is deprived of it, a longing desire takes possession 
of him. He is unfitted for work or for enjoyment until 
another dose of the poison has been administered. 
So pronounced is the opinion of the best people against 
the use of the cigarette that a number of states have 
passed laws prohibiting their sale. The supreme court 
of Tennessee made the following statement: "We think 
cigarettes are not legitimate articles of commerce, because 
they are wholly noxious and deleterious to health. Their 
use is always harmful, never beneficial. They possess 
no virtue, but are inherently bad, and bad only. They 
find no true commendation or merit or usefulness in any 
sphere. On the contrary, they are widely condemned as 
pernicious altogether. Beyond question their every tend- 
ency is toward the impairment of physical health and 
mental vigor." 
Crime and Cigarettes. - Some railroad companies and 
numerous other business corporations demanding workers 
mentally, physically, and morally sound refuse to employ 
a person who is a cigarette smoker. The probation officer 
at Kansas City said that of 90 boys who had been PATENT MEDICINES 
71 
put in jail during six months of 1902 all but two 
were addicted to the use of cigarettes. A police magis- 
trate in New York declares that 99 out of every 100 boys 
between the ages of ten and seventeen years who come be- 
fore him charged with crime have their fingers stained 
with nicotine from cigarettes. 
Opium and Morphine. - Opium is a sleep-producing drug 
made from the milky juice dripping out of the cut fruit 
capsules of the white poppy. The plant is grown in Asia 
Minor, Persia, and India. Morphine is a white powder 
separated from the opium by a chemical process. It is 
four times as strong as opium. Neither opium nor mor- 
phine should be taken except by the advice of a physician. 
Persons sometimes begin the use of these drugs to relieve 
them from pain or produce sleep, and after a few days' or 
weeks' use are unable to stop taking them. Like alcohol, 
they create an unnatural appetite which is only satisfied 
by constantly larger doses. Hundreds of persons are 
being treated yearly in sanitariums and otherwise to help 
them break loose from this terrible habit of using mor- 
phine and cocaine. Cocaine is made from the leaves of 
the coca plant. The numerous advertisements in the 
papers stating that medicines will be sent at slight cost to 
cure the morphine, cocaine, or alcohol habit are issued by 
fraudulent persons seeking to rob unfortunate people. 
Laudanum is a mixture of opium, alcohol, and water, 
and is therefore a dangerous drug. Paregoric is a com- 
pound of opium, alcohol, camphor, and some other drugs. 
Patent Medicines. - Most of the liquid patent medicines 
are stimulants or narcotics. Some have both properties. 
The narcotic contained in many of them is alcohol. 72 
NARCOTICS AND STIMULANTS 
Nearly all contain more alcohol than beer, and many are 
richer in alcohol than the strong wines. A few have 
nearly as much alcohol as whisky has. It is just as dan- 
gerous and just as wrong to use these patent medicines as 
it is to use wine, whisky, or beer. The help which these 
nostrums seem to afford the sick is generally due to the 
alcohol which makes one feel good for a time. Late 
Fig. 43.-Diagram showing the amount of alcohol in some of the alcoholic 
drinks and patent medicines. 
investigations have shown that patent medicines have 
wrecked many lives and caused numerous untimely 
deaths. 
Soothing sirups for children contain some kind of 
opiates which may ruin the constitution of a child. Most 
of the advertised remedies for coughs owe their soothing 
qualities to morphine or opium. Nearly all catarrh pow- 
ders give temporary relief only because they contain opium 
or cocaine. Every one should remember that the constit- 
uents of the patent medicines claiming to cure all disease 
are known to our trustworthy physicians. If these reme- COFFEE 
73 
dies helped the sick without injuring the health, they 
would of course be used by the reputable doctors. Some 
of our best newspapers and magazines, having lately 
learned of the worthlessness and evil effects of patent 
medicines, have refused to advertise them. 
Tea. - Tea consists of the dried leaves of an evergreen 
plant grown in China. There are two general classes of 
teas, the one being black and the other green. Black tea 
is prepared by exposing the fresh leaves to the rays of 
the sun and later rolling and breaking them up. They 
are then allowed to ferment, after which they are again 
exposed to the sun and then dried in the oven. 
In preparing green teas, the leaves are withered by heat 
or steamed, then broken up and sweated in bags, and 
finally roasted. For general use black tea is preferable to 
green tea because the tannic acid in it is less soluble. 
Tannic acid delays digestion, and on this account green tea 
used at mealtime may produce dyspepsia. In order to 
make any kind of tea so as to contain as little tannic acid 
as possible, the leaves should be placed in a jar and have 
boiling water poured on them. The jar must then be 
covered a few moments, after which the liquid tea is to be 
poured off into a clean vessel. 
Tea contains practically no nourishment. The stimu- 
lating effect is due to caffein. The drinking of large 
quantities of tea may cause dyspepsia, heart trouble, sleep- 
lessness, and other nervous disorders. Tea should not be 
used by children. 
Coffee. - Coffee is prepared from the seeds of the coffee 
plant grown in Arabia, Java, Costa Rica, and Brazil. 
The seeds, often called beans, are made ready for use by NARCOTICS AND STIMULANTS 
74 
being dried in the oven, then roasted and ground. A cup 
of black coffee contains about as much tannic acid and 
caffein as a cup of strong tea. 
It stimulates mildly the brain and heart and deepens 
the respirations. Coffee should not be taken by children 
or by those in ill health, as it tends to disturb digestion, 
and to produce nervousness and sleeplessness. 
Chocolate. - Chocolate is made by grinding to fineness 
the kernels of the roasted seeds of the cacao tree. Chocolate 
contains a considerable amount of fat, starch, andproteids, 
and on this account it makes a nutritious drink. It also 
contains a small quantity of a mild stimulant which has 
little effect on the body. Cocoa differs from chocolate in 
that it has been deprived of a portion of its fat and has 
been more finely pulverized. It is an excellent drink for 
children and those recovering from illness. 
Alcoholic Beverages. - Alcohol is such a health de- 
stroyer, has ruined so many homes, and resulted in so 
much crime and poverty, that an entire chapter is later 
devoted to the subject. While it is true that an adult 
can occasionally take a drink of wine, beer, or whisky 
without injury to health, yet there is always the probability 
that he may before he is aware of it develop the alcohol 
thirst. These drinks often wreck not only the body but 
also the character. 
Questions 
1. How does a narcotic differ from a stimulant? 2. Name some 
narcotics and stimulants. 3. From what is tobacco made? 4. How 
does tobacco injure the health? 5. Give evidence showing that tobacco 
is injurious to the young. 6. Why is the cigarette more harmful than 
the pipe or cigar ? 7. Why have some states made laws preventing SUGGESTIONS TO THE TEACJIER 
75 
the sale of cigarettes ? 8. What evidence is there that cigarettes make 
criminals? 9. Why should one never use opium or morphine except 
on a physician's prescription? 10. State some facts about patent 
medicines. 11. Explain the danger in using soothing sirups and 
catarrh powders. 12. How is tea prepared for the market ? 13. What 
is the proper method of making tea ? 14. Of what use are tea and 
coffee ? 15. In what way does cocoa differ from chocolate? 
Suggestions to the Teacher 
1. Boil for ten minutes an ounce of tobacco in a half pint of water. 
Place in the tobacco tea thus made an earthworm, a tadpole, or a snail, 
and note how soon it becomes unconscious from the narcotic effect of 
the tobacco. 
2. Ask some of the children to make tea at home by boiling the 
leaves in water, and then make another cup of tea by merely pouring 
boiling water on the leaves. Note the difference in taste. 
3. Assign to several members of the class the preparation of brief 
reports on the ingredients and use of certain harmful patent medi- 
cines. Information may be obtained from a booklet, The Great 
American Fraud, referred to on page 13. • IX. THE DIGESTIVE SYSTEM 
THE ALIMENTARY CANAL 
The general cavity within the body is divided into two 
parts by the diaphragm, which is a dome-shaped sheet of 
muscle and tendon. Above the diaphragm is the thoracic 
cavity, surrounded by the ribs and other bones and also 
muscles forming the thorax. It contains the heart, lungs, 
esophagus, and large blood vessels. Below the diaphragm is 
the abdominal cavity, surrounded by structures constituting 
the abdomen. It holds the stomach, liver, spleen, pancreas, 
kidneys, bladder, intestines, and many large blood vessels. 
All the organs in the body cavity form the viscera. They 
are enveloped by a semitransparent, glistening membrane, 
named serous membrane because of the colorless fluid, the 
serum, which it extracts from the blood. It is this 
fluid which allows the organs to move freely against one 
another without friction. The serous membrane of the 
thoracic cavity is known as the pleura, while that in the 
abdominal cavity is called peritoneum. 
Parts of the Digestive System.-The collection of 
organs used in grinding, mixing, dissolving, and otherwise 
changing the food so as to render it capable of being 
absorbed by the blood, together with the canal used in 
carrying the rejected remnants of the food out of the body, 
constitutes the digestive system. It consists of two chief 
parts, the alimentary canal and the assisting glands of 
digestion. 
76 THE MOUTH 
77 
The divisions of the alimentary canal are the mouth, 
pharynx, esophagus, or gullet, stomach, and the coiled 
tube called the intestines filling up 
much of the abdominal cavity be- 
low the liver and stomach (Fig. 44). 
The assisting glands are for the pur- 
pose of secreting from the blood a 
liquid for softening and dissolving 
the food so that it may be taken into 
the tissue. They are the salivary 
glands, forming the saliva or spit, 
and the liver and pancreas, adjacent 
to the stomach. 
Mucous Membrane. - All sur- 
faces exposed to the air are covered 
with one or more layers of epithelial 
cells. If the surface is not freely 
exposed, so that it may be cleansed 
by air, sunshine, and washing, the 
cells have the power to make from 
the blood a thin, slippery substance 
called mucus to serve as a cleanser. 
Such mucus-secreting cells, with 
the thin layer of underlying con- 
nective tissue, form mucous mem- 
brane (Fig. 45). It lines the entire 
alimentary canal and all other 
tubes of the body touched by air. 
The Mouth. -The important organs in the mouth are 
the tongue and teeth. The tongue is composed of several 
niuscles covered with mucous membrane, and is used in 
Fig. 44. - Diagram showing 
the relations of the organs 
of the body cavity, viewed 
from the side, a, vermi- 
form appendix; c, spinal 
column inclosing the spinal 
cord; d, diaphragm; e. 
esophagus; i, the great vein, 
or vena cava ; k, kidney; 
lu, lung; li, large intestine; 
p, pancreas; s, spleen; t, 
trachea; u, ureter; v, vena 
cava. 78 
THE DIGESTIVE SYSTEM 
speaking and in moving the food 
about in masticating. In the adult 
there are 32 teeth, eight being in 
either half of each jaw. Because of 
their chisel shape, the two front ones 
in the half of each jaw are called 
incisors. The next one is the canine, 
the two following are the premolars, 
or bicuspids, and the three farthest 
back are the molars. 
The incisors are for the purpose of 
cutting the food, while the molars, 
with their large, flat, grinding sur- 
faces, serve to crush it. The teeth 
are set firmly in sockets about a half 
inch deep in the jaw bones. The thickened mucous 
membrane in the region 
of the teeth forms the 
gums. 
Milk Teeth. - An in- 
dividual living to ma- 
turity has two sets of 
teeth. The first set, 
called milk or tempo- 
rary teeth, are twenty 
in number. The two 
middle incisors of the 
lower jaw usually appear 
at the age of from, four 
to eight months. A 
few weekt^ l^cr the t\yo 
Fig. 45. - Section across 
a mucous membrane, 
showing blood vessels. 
Magnified, e, epithelial 
cells. 
Fig. 46. - Mounted set of adult teeth. Photo- 
graphed in the Wistar Institute of Anat- 
omy. Viewed from the right side, i, in- 
cisors; c.canine; p,premolars; m,molars, Al ILK TEETH 
79 
middle incisors of 
the upper jaw break 
forth. At the end 
of the first year, the 
child should have all 
the eight incisors. 
The first four molars, 
the four canines or 
eye teeth, and the 
last four molars ap- 
pear in the order 
named, during the 
second year. About 
the seventh year of 
age the permanent teeth begin to grow beneath the 
milk teeth, and by pressure against the blood vessels cut 
off their nourishment, caus- 
ing the roots to be absorbed, 
so that the milk teeth drop 
out between the seventh and 
twelfth year, or may be 
easily pulled, as they are 
held fast only by mucous 
membrane. 
Sometimes the second set 
of teeth do not press in such 
a way as to cut off the 
nourishment of the first set, 
but appear at the inner or 
outer side of them. Unless 
the milk teeth are then ex- 
Fig. 47. - Roof of the mouth of a skull of a boy 
18 years old. The last molars or wisdom teeth 
are breaking through. Photographed in the 
Wistar Institute of Anatomy. 
Fig. 48. - Milk teeth of a child from 
the left side, c, incisors; i, ca- 
nines; m, premolars. Photo- 
graphed in the Wistar Institute 
of Anatomy. 80 
THE DIGESTIVE SYSTEM 
traded, the permanent ones will project and disfigure the 
countenance and also be in the wrong position for chew- 
ing. The twelve permanent molar teeth are not preceded 
by any temporary teeth. The first pair of these in each 
jaw appear at the age of six years; the second pair 
during the twelfth or 
thirteenth year ; and 
the last pair, called 
the wisdom teeth, break 
through between the 
seventeenth and twenty - 
fifth year of life. 
Structure of a Tooth. 
- The part of a tooth 
above the gum is the 
crown, the part below 
the gum is the root, or 
/a^and the constricted 
region between these two 
parts is the neck. The 
hard interior part of a 
tooth is the dentine, 
which is a bonelike sub- 
stance. The crown is covered with a very hard, glisten- 
ing substance known as enamel, while the surface layer 
of the fang is cement. The small cavity within the 
tooth is filled with pulp, which is a soft mass of fatty 
material, together with blood vessels and nerves entering 
at the tip of the root. The two large tusks of the elephant 
used for ivory are the overgrown incisor teeth made of 
very compact dentine. 
Fig. 49. - Part of a skull, with the side 
of the jaw bone cut away to show the 
teeth, a, e, n, I, and i ready to break 
through the gum. Photographed in the 
Wistar Institute of Anatomy. CARE OF THE TEETH 
81 
Care of the Teeth. - There are always living in the 
mouth several kinds of bacteria, some of which, when 
present in large num- 
bers, cause the teeth to 
decay. Therefore the 
teeth should be brushed 
twice daily with a brush 
dipped in warm water. 
Fig. 51.- Section from before backward 
through the front part of the head. 
ad, Adam's apple, or cartilage of the 
larynx; an, nostrils, or anterior nares; 
be, mouth; ep, epiglottis; e, Eustachian 
tube; n, soft palate; pn, posterior 
nares; ph, pharynx; lx, larynx; oe, 
esophagus; sc, spinal cord; se, part 
of the septum turned up; sp, dividing 
the nostrils; tr, trachea; tn, tonsil 
partly hid by the uvula; v, is just 
above the vocal cord. 
Fig. 50. - Section through a 
tooth, a, crown; b, neck; c, 
fang; d, pulp of blood vessels 
and nerves; e, dentine; f, 
enamel; g, cement; h, nerve. 
The removal, after eating, of the particles of food cling- 
ing to the teeth, by means of a strong thread or wooden 
toothpick, will help much in preventing decay. A metal 
pick should never be used, as it is likely to break or 
DAV. PHYS. 6 82 
THE DIGESTIVE SYSTEM 
scratch the enamel, and it is this hard covering which 
prevents the bacteria from entering the dentine to cause 
decay. The enamel is often broken by cracking nuts or 
biting other hard substances. 
The whitish material called tartar is a limy deposit from 
the saliva. It should 
be removed once or 
twice a year by a den- 
tist, who can then dis- 
cover any cavities pres- 
ent and at once fill 
them, thus stopping 
further decay. The 
milk teeth as well as 
the permanent set fre- 
quently decay and need 
to be filled. Poor teeth 
lead to ill health in 
many persons and are 
responsible for much 
neuralgia and indiges- 
tion. 
Pharynx and Esoph- 
agus. - The irregular 
cavity back of the mouth and in the throat region is the 
pharynx. The passages conducting air through the nose 
open into its top part, and from either side a small canal 
called the Eustachian tube leads up to the middle ear, 
while from the back part extend the esophagus and larynx. 
The conical body hanging from the soft palate forming 
the roof of the posterior portion of the mouth is the uvula. 
Fig. 52. - Front view of the viscera, a, 
spleen; b, heart; d, diaphragm ; e, liver; 
g, lung; h, stomach; i, large intestine; 
j, small intestine; k, bladder. THE STOMACH 
83 
An oval body a half inch long and buried in the mucous 
membrane on either side of the root of the tongue is the 
tonsil. Its use is unknown. A 
growth of certain bacteria on it 
and other parts of the throat 
causes tonsilitis, which may be 
conveyed from one member of a 
school to another by the use of 
a common drinking cup. 
The pharynx narrows into 
the esophagus just back of the 
larynx, whose large part forms 
beneath the chin a projection 
known as Adam's apple. The 
esophagus is a half inch in diam- 
eter and nine inches long. Its 
muscular coat aids in propelling 
food from the mouth to the 
stomach, and the mucous lining 
secretes enough fluid to keep the 
interior well moistened. 
The Stomach.-The esophagus 
opens below the diaphragm into 
the stomach. This is an en- 
largement of the alimentary 
canal for the purpose of hold- 
ing the foods from one to five 
hours while the juices it secretes 
act on them. It has the form of 
a long hen's egg, and is capable of holding over two quarts. 
Its muscular coat, made of involuntary muscle arranged ir 
Fig. 53. - Front view of the 
organs of digestion removed 
from the body, a, c, and e, 
colon; d, duct of the gall 
bladder; dm, diaphragm; g, 
gall bladder; h, hepatic duct 
from the liver; k, kidney; l,i, 
small intestine; Iv, liver; n, 
opening of the bile duct in- 
to the small intestine; oe, 
esophagus; pn, pancreas; r, 
rectum; st, stomach; sp, 
spleen; vx, vermiform ap- 
pendix. 84 
THE DIGESTIVE SYSTEM 
three layers, keeps the food in motion while the glands of 
the mucous membrane force out the gastric juice. This 
softens and more or less dissolves the food, which is re- 
tained the proper time by a circular muscle forming the 
pylorus, the opening of the stomach into the intestine. 
The Intestines. - The small intestine is a very much 
coiled tube about 25 feet in length, and is over an 
inch in diameter. The 
two layers of involun- 
tary muscle forming the 
muscular coat serve to 
move the food along 
and mix it with the 
secretion from the thou- 
sands of little glands 
forming much of the 
inner or mucous coat. 
From this coat millions 
of minute, fingerlike processes, the villi (Fig. 61), no 
thicker than a hair and one sixteenth of an inch 
long, project and take up the nourishing portions of the 
food. 
The small intestine leads by a valve into the large 
intestine at the lower right side of the abdominal cavity. 
The colon and rectum are the main parts of the large 
intestine. 
Vermiform Appendix. - The vermiform appendix is a 
blind tube projecting from the large intestine. It is as 
large around as a lead pencil and from one to six inches in 
length. Its cavity is scarcely larger in diameter than the 
head of a pin, so that it sometimes becomes clogged up 
Mg. 54. - The small intestine joining the 
large one. ap, vermiform appendix; c, 
beginning of the large intestine; co, 
colon; sm, small intestine. THE NATURE OF A GLAND 
85 
with material from the intestine. This may cause a very 
rapid growth of the bacteria present, and as a result the 
organ becomes inflamed and often must be removed to 
prevent the bacteria from eating through into the abdomi- 
nal cavity. This inflammation of the appendix is called 
appendicitis. 
The appendix has no function in man at present, but 
long ago, in prehis- 
toric times, it was 
wider and longer, and 
then was perhaps of 
service in digestion, 
as is the case now in 
the rabbit, ground- 
hog, and cow. 
DIGESTIVE GLANDS 
The Nature of a 
Gland. - A gland is 
a simple tube lined 
with cylindrical 
cells, or a collection 
of such tubes, all 
of which may be 
branches of the one 
main tube called a 
duct. The purpose 
of a gland is to manufacture some special material from 
the blood. The thousands of gastric glands in the walls 
of the stomach and the intestinal glands of the intestines 
are simple or slightly branched tubes too small to admit 
Fig. 55. - Diagram of a gland, c, alveolus, 
or enlarged end of tube; i, common duct to 
carry off the secretion made by the cells from 
that part of the blood passing through the 
walls of the capillaries; a, arteries; v, veins. 86 
THE DIGESTIVE SYSTEM 
a hair. Nearly all mucous membrane contains in it glands 
for secreting mucus with which to moisten the surface and 
prevent the entrance of germs. 
Salivary Glands. - Three pairs of very richly branched 
salivary glands pour their secretions into the mouth. The 
parotid gland lying just 
beneath the skin and be- 
low the ear forms an 
irregular, flat mass 
about as large as the 
ear. Its duct opens on 
the inner side of the 
cheek. The submaxil- 
lary gland is somewhat 
the size and shape of an 
almond, and lies be- 
tween the lower jaw 
and base of the tongue. 
Its duct opens beneath 
the tongue on a papilla 
visible to the naked eye. 
The sublingual gland is 
the smallest, and lies 
under the tongue in front of the submaxillary. Its 
several ducts open beneath the tongue. The secretions 
of these three pairs of glands, together with the glands of 
the mucous membrane of the mouth, form the saliva, 
which acts on the starch of food. 
Gastric Glands. - The mucous membrane lining the 
stomach is composed almost entirely of tubelike gastric 
glands arranged side by side and held in place by a little 
Fig. 56. - Skin removed and front part of the 
lower jaw cut away to show the salivary 
glands, pa, parotid gland; su, submaxil- 
lary gland; si, sublingual gland; dt, duct 
of parotid gland; d, duct of submaxillary 
gland; t, tongue. INTESTINAL GLANDS 
87 
connective tissue between them. They yield pepsin, 
rennin, and hydrochloric acid. These substances, dissolved 
in a watery liquid 
issuing also from 
the glands, form the 
gastric juice which 
acts on the proteids 
of the food. 
Intestinal Glands. 
- The mucous 
membrane of the 
intestine is com- 
posed largely of 
simple, tubelike 
glands standing 
side by side, with 
their mouths open- 
ing at the bases of 
the villi which stick 
out into the cavity 
of the intestine. 
These glands se- 
crete about three 
quarts daily of a watery fluid containing several products 
of great importance in digestion. 
The Liver. - The liver is of a brownish red color, and 
is the largest gland in the body, being about equal in size 
to the upper half of the head. It lies immediately under 
the diaphragm. A number of deep incisions separate it 
into five lobes, each of which is made of thousands of lobules 
about the size of a pin's head. A lobule consists of several 
Fig. 57. - Diagram of a tiny block of tissue 
smaller than a pin's head, cut from the wall of 
the stomach, a, mucous membrane; c and d, 
muscular coats; e, mouths of gastric glands; 
h, gastric glands; i, capillaries supplying the 
gastric glands with blood; m, artery; n, vein. 88 
THE DIGESTIVE SYSTEM 
hundred cells having the power of separating certain 
substances from the blood and manufacturing them into 
a dark green liquid called bile. This escapes from the 
liver through the hepatic duct leading to the small intes- 
tine near its junction 
with the stomach. 
A branch from the 
hepatic duct carries 
the excess of bile 
to the gall cyst, or 
gall bladder, where it 
is stored until needed 
for digestion. The 
liver receives the 
sugar absorbed by 
the blood vessels from 
the intestines, stores 
it, and deals it out as needed by the body. It also aids in 
freeing the blood of poisons and waste. 
The Pancreas. -The pancreas is a pinkish white gland 
having somewhat the shape and size of the little-finger 
half of the hand. In butchered animals it is known as 
one of the siceetbreads. It extends from the curve of the 
stomach end of the small intestine across the body back of 
the stomach. Its cells form nearly a quart of juice daily, 
which is carried by numerous small ducts into a larger 
tube, the pancreatic duct. This enters the small intestine 
with the bile duct. Sickness of certain kinds of cells 
scattered in bunches throughout the pancreas causes 
diabetes, an incurable disease characterized by sugar in 
the blood. 
Fig. 58. - Front view representing the stomach 
pulled up to show the pancreas, a, aorta; 
c, gall bladder; d, stomach end of the small 
intestine; e, esophagus; o, liver; sp, spleen. SUGGESTIONS FuB THE TEACHER 
89 
Questions 
1. Name the contents of the thoracic cavity. 2. What organs are 
located in the abdominal cavity ? 3. What is the peritoneum ? 
4. Name the assisting glands of digestion. 5. Describe a mucous mem- 
brane. 6. Give eight facts concerning an adult's teeth. 7. At what 
age do the milk teeth appear? 8. When do the milk teeth give place 
to the permanent teeth? 9. Name the parts of a tooth. 10. Give 
some points concerning the care of the teeth. 11. Name the parts 
seen in your mouth wide open when you are standing before a mirror. 
12. What is a tonsil? 13. Locate the stomach. 14. Write five im- 
portant facts about the intestines. 15. What is a gland ? 16. Locate 
the salivary glands. 17. Give three facts about the gastric glands. 
18. Describe the liver. 19. Point out the location of the liver on your 
own body. 20. State five facts concerning the pancreas. 
Suggestions for the Teacher 
1. Exhibit a full set of teeth, which may usually be had for the 
asking from a dentist. Crack a tooth open and note the structure. 
2. Ask the children to examine the mouths of the younger ones at 
home and report what teeth are present and whether any are coming 
in out of place. 
3. The entire alimentary canal of a cat, squirrel, or rabbit may be 
removed from a freshly killed animal and kept for demonstration for 
many years, if placed in a jar of formaldehyde solution (formaldehyde, 
three tablespoonfuls, and water, one quart). X. HOW FOOD IS DIGESTED 
The Meaning of Digestion. - When food is taken into 
the mouth, it is not in such a state that the blood vessels 
are able to absorb it and carry it to the cells in all parts 
of the body. Dry food to be readily swallowed must be 
broken up and well moistened. The stomach is of such a 
nature that it will usually not allow any substance to pass 
out of it before the substance has been softened and made 
into a liquid state. The food on reaching the intestine 
is changed into a more perfect solution. 
The operations of chewing, softening, dissolving, and 
otherwise changing the food so as to fit it to pass through 
the cell walls into the vessels for transportation, constitute 
the process called digestion. The changes produced in the 
food digested are due largely to the ferments made by 
the glands in the walls of the alimentary canal and by the 
salivary glands and pancreas. Ferments are substances 
formed by living cells and are capable of acting on food 
without any change taking place in themselves. About 
a dozen kinds of ferments are generated in the body. 
Mouth Digestion. - The touch, taste, and odor of food 
cause the salivary glands to send forth an abundance of 
saliva. About one pint is secreted daily. It contains the 
important ferment which acts on the starch of foods so as 
to change it to sugar. The time required for this trans- 
formation is from ten minutes to twenty minutes for 
90 TASTE AND ODOR OF FOOD 
91 
cooked foods, and from one hour to two hours for chose 
uncooked. 
The saliva does not continue to act on the food more 
than an hour after it enters the stomach, because the food 
has then become mixed with the acid gastric juice, which 
stops the action of the ferment. 
Importance of Thorough Mastication.-Mastication means 
chewing the food. It has been well and truthfully said 
that if every mouthful of food 
were chewed for one minute, the 
common complaint about indiges- 
tion would seldom be heard. Much 
chewing of food produces much 
saliva and a complete mixture of 
the two, so that the ferment may 
reach every particle of the starch. 
Moreover, the pleasant taste and 
odor of food, prolonged by mas- 
tication, excite the flow of the 
digestive juices in the stomach. 
Gladstone is said to have accounted 
for his long life and excellent 
health by the fact that he chewed 
each mouthful of food at least 
thirty times. 
Taste and Odor of Food. -In the dozen or more large 
circumvallate papillae on the back part of the tongue and 
in other portions of the tongue and mouth cavity are mi- 
nute oval bodies called taste buds or organs of taste. From 
each a nerve fiber leads to the brain. The food which 
excites these end organs must be in solution, and for this 
Fig. 59. - Top view of the 
tongue. I, circumvallate 
papillae; e, epiglottis. 92 
HOW FOOD IS DIGESTED 
the watery saliva is well adapted. A minute or two is 
often required to effect this solution, and because of this, 
food swallowed hastily has but little taste. Since any- 
thing pleasant to the taste stimulates greatly the flow of 
the digestive juices, it is wise for one to select delicious 
eatables. Much of the pleasing effect of taking food is 
due to the odor. Such articles as coffee, tea, grapes, 
horse radish, and onions affect the sense of smell much 
more than that of taste. This may be readily determined 
by holding shut the nostrils while chewing and swallowing. 
The Chewing of Gum and Tobacco. - Pepsin chewing- 
gum, which is widely advertised as a remedy for indiges- 
tion, owes its usefulness not to the pepsin it contains but 
to the pepsin which it causes the stomach to produce. 
The sweet taste and the chewing act on the nerves con- 
trolling the flow of the saliva and the gastric juice. The 
chewing of dry bread or crackers aids digestion quite as 
much as the use of gum. 
The chewing or smoking of tobacco causes a great waste 
of valuable saliva, as it is spit out of the mouth. On this 
account the use of tobacco is an uncleanly habit as well as 
an unhealthy one, especially for the young. The stale odor 
always clinging to the person and clothing of the constant 
user of this weed is very unpleasant to most women and 
many men. Tobacco not only lessens the natural appetite 
for food and the power of digestion, but has such a perni- 
cious effect on the health of youth that the Minister of 
Public Instruction in France issued a circular forbidding 
the use of tobacco in the public schools. 
Stomach Digestion. - The food at the first part of a meal 
is, in a few minutes after entering the stomach, mingled MOVEMENTS OF THE STOMACH 
93 
with the acid gastric juice, but that entering later is not 
affected by the stomach secretions for a half hour or more. 
It remains near the entrance, and the saliva from the 
mouth continues its action. The gastric juice is composed 
of a watery liquid containing a small amount of hydro- 
chloric acid, pepsin, and rennin. The last two are ferments. 
Pepsin changes the proteids to peptones so that they can 
be taken up by the blood vessels of the intestines. Ren- 
nin curdles milk. The food, when ready to pass from the 
stomach through the pylorus, is similar to thick gravy and 
is called chyme. 
How the Gastric Juice is Formed. - The 5,000,000 mi- 
croscopic tubelike glands completely lining the interior of 
the stomach manufacture from the blood the gastric juice. 
The glands are made to act either by the taste and odor 
of food or by the presence of food in the stomach. At the 
beginning of the meal certain foods, such as cake, bread, 
and potatoes, cause a much less flow of juice than soups 
and meat. On this account a small amount of soup at the 
beginning of the meal is helpful to digestion. As a pleas- 
ing odor and taste tend to increase the amount of stom- 
ach secretion, the kind of food easily digested by one per- 
son may cause dyspepsia in another. Grief or mental 
excitement tend to decrease the action of the gastric 
glands. 
Movements of the Stomach. - In order that the food 
may be moved forward and mixed with the gastric juice, 
the stomach must perform certain movements. It was 
once thought that these movements were of such a nature 
as to cause the contents of the organ to pass round and 
round from one end to the other. Lately it has been HOW FOOD IS DIGESTED 
94 
shown by the use of the X rays on man and by experiments 
on rats that no such rotary motion of the food occurs. 
The large end of the stomach has little or no motion, while 
contraction of the circular fibers begins about the middle 
and extends toward the pylorus, squeezing and mixing 
the food with the juices. One wave of contraction after 
another begins at the middle and progresses toward the 
small intestine, tending 
to press the contents of 
the stomach into the in- 
testine. The material 
is prevented from leav- 
ing the stomach by 
the contraction of a 
ring of muscle, the py- 
loric valve, which re- 
laxes only when pushed 
against by a liquid. 
Time Required for Digestion. - The length of time re- 
quired for gastric digestion depends upon how well the 
food is masticated, how it is cooked, the kind of food, and 
the character of the gastric juice. The strength of the 
gastric juice is much greater in healthy adults than in in- 
fants and invalids. Observations on the food in the 
stomach have been made through a hole formed by a 
gunshot wound, and further information as to digestion 
has been gained by pumping out the contents through 
a rubber tube at various intervals after certain kinds 
of products have been eaten. The following tables show 
the time required for the digestion of some of the common 
foods: - 
Fig. 60. - The stomach, with the circular 
muscle fibers removed from the right half 
to show the other muscular fibers. USE OE FLUIDS WITH MEALS 
95 
Hours 
Rice, boiled 1 
Eggs, raw and whipped . . 1| 
Eggs, raw 2 
Eggs, soft boiled 3 
Eggs, hard boiled . . . . 3| 
Milk, boiled 2 
Milk, raw 2| 
Brains, boiled 1| 
Potatoes, roasted . . . . 2| 
Beans, in pod, boiled . . . 2J 
Hours 
Beef, boiled 2| 
Beef, roasted 3 
Beef, fried 4 
Oysters, raw 2| 
Oysters, stewed 3| 
Bread, white 3| 
Bread, corn 3| 
Mutton, roasted 3{ 
Pork, roasted 3| 
Cabbage, boiled 4| 
Results of Overeating. - When the stomach is too full, 
its natural movement cannot take place. As a result, the 
gastric juice is small in quantity and changed in quality 
and is not properly mixed with the food. These conditions 
cause an irritation of the nerve endings in the lining of 
the stomach, producing a feeling of sickness. If then the 
pylorus does not allow the undigested food to pass, vomit- 
ing occurs. Many headaches are due to an overloading 
of the stomach. Eating more than three times a day is 
likewise unhealthy for any one except invalids and chil- 
dren whose diet consists largely of milk. The digestive 
glands are prevented from resting, and therefore give out 
a weak juice of poor quality. Candies and other sweets 
often cause digestive disorders if taken at any other time 
than at the close of the meal. 
Use of Fluids with Meals. -Very hot or very cold fluids 
hinder digestion, because they decrease the flow of the 
gastric juice. The use of more than one glass of water at 
a meal is usually not desirable, as the stomach secretion is 
liable to be too much diluted. It is especially harmful to 
wash the food down the throat by taking a swallow of 
coffee or tea after every two or three bites of food. 96 
HOW FOOD IS DIGESTED 
A vast amount of experience shows it is unwise to use 
habitually beer, wine, ale, or any other form of alcoholic 
drink. The large amounts of these narcotics so often 
taken hinder digestion. The Committee of Fifty, who 
recently studied this question, state that chronic inflam- 
mation and catarrh of the stomach are common among 
those using alcohol to excess. Dr. Woodhull, of the 
United States Army, says: " Its use in health only disturbs 
health, leading to numerous diseases. So much ill health 
ultimately depends upon alcoholic indulgence that the 
habitual drinker both lays the foundation for serious 
disturbances and steadily builds upon it." The govern- 
ment reports of Switzerland, where alcohol is moderately 
used, state that one in every ten deaths of men over twenty 
years of age results from alcohol. Wine may in rare 
cases be of some benefit to digestion, but the late work of 
Horsley and Sturge shows that alcohol enfeebles the churn- 
ing action of the stomach and thus delays digestion. 
Intestinal Digestion.- The most important part of the 
digestive process is carried on in the small intestine. In 
order that the liquid chyme may be thoroughly acted on 
by the juices in tire intestine, it is forced out by the 
stomach in small amounts at intervals of one or two 
minutes. Two or three quarts of intestinal juice are 
secreted daily by the microscopic tubular glands forming 
much of the lining of the intestine. This juice contains 
four ferments, one of which splits up the proteids, another 
changes the common sugar to grape sugar, and a third 
stimulates the flow of the pancreatic secretion. 
Pancreatic Juice. - The pancreas secretes nearly a quart 
of fluid daily, which contains the most important of all MOVEMENTS OF THE INTESTINES 
97 
the ferments for digestion. One changes starch to sugar, 
a second transforms the proteids into peptones, and a third 
splits the fats into glycerin and fatty acids. The acids 
unite with some of the alkali present in the bile and other 
juices, and thus form soap. In this way the starch which 
escapes the action of the saliva, and also the proteids un- 
changed by the gastric 
juice, are perfectly di- 
gested in the intestine. 
The dark liquid mass of 
food material, composed 
largely of peptones, soap, 
and sugar, is now ready 
for absorption, and is 
called chyle. 
The Bile. - The bile is 
a greenish yellow liquid 
which is secreted by the 
liver at the rate of more 
than a pint daily. When 
there is no food in the 
intestine, it is stored in the gall bladder, capable of hold- 
ing a third of a teacupful. The bile has in itself no diges- 
tive power, but hastens the action of some of the other 
j uices. It also contains some waste matter from the body. 
When the bile duct becomes clogged, much of the fats 
escapes digestion, and the bile then gets into the blood and 
produces a disease called jaundice. 
Movements of the Intestines. - The longitudinal and 
circular muscular coats serve to give two movements 
to the intestines. Peristalsis or the peristaltic movement 
Fig. 61. - Slice of the wall of the cat's 
small intestine, i, villi; n, intestinal 
glands; m, muscular coat. Magnified. 
DAV. PHYS. 7 98 
HOW FOOD IS DIGESTED 
consists of a wave of contraction of the circular muscle, 
which passes along from the stomach end onward, and thus 
presses the food down the canal. Another movement is 
the swinging to and fro of several folds of the intestine 
by a kind of rhythmical contraction of the circular and 
longitudinal muscles. 
These motions not only 
propel the food toward 
the large intestine, but 
also mix it thoroughly 
with the digestive 
juices. 
The food remains in 
the small intestine from 
five hours to fifteen 
hours, during which 
time most of the 
nourishing part is ab- 
sorbed into the blood. 
The refuse passes into 
the large intestine, from 
which it should be 
ejected daily at about the same hour. Failure in perform- 
ing this important act regularly causes constipation, which 
results in much ill health. 
Absorption from the Intestine. - More than nine tenths 
of all the food reaching the blood has been absorbed by the 
villi of the small intestine. There are more than 20,000 
of them to every square inch. Each villus is composed 
chiefly of a layer of cylindrical cells covering a core 
made of a network of blood capillaries surrounding a-sin- 
Fig. 62. - Slices of the small intestine. 
m, cat; n, human. A score of villi are 
seen on the intestine of the cat. The 
four folds of the mucous coat seen in 
the human intestine bear dozens of villi 
appearing as tiny shaggy projections 
scarcely separated from one another. 
Magnified. THE LACTEALS 
99 
gle vessel leading into the lacteal system (Fig. 63). The 
food passes through the epithelial cells, and then the fats 
are taken up by the lacteal vessels, while the other part 
of the food is absorbed by the blood capillaries uniting 
to form the portal 
system leading to 
the liver (Fig. 64). 
The Lacteals. - 
These vessels form 
a part of the lymph 
system,which serves 
to return to the 
veins in the neck 
that portion of the 
blood constantly 
oozing out of the 
capillaries in all 
regions of the body. 
The lacteals consist 
of millions of mi- 
nute vessels begin- 
ning blindly in the 
villi and other parts 
of the intestine and 
uniting into a score 
or more of threadlike tubes which converge in their 
course to enter the lower part of the left thoracic duct 
(Fig. 64). This duct is a tube about as large as a lead 
pencil, lying in front and to one side of the backbone. 
It leads into a large vein in the neck. The fats, upon 
entering the lacteals, are forced along by the pressure of 
Fig. 63. - Diagram of the structure of a block 
of tissue smaller than a pin's head, cut from the 
wall of the small intestine, a, mouths of the 
intestinal glands; b, villus cut lengthwise to 
show the blood capillaries and white lacteal 
within; e, lacteal vessel sending branches to 
many villi; i, intestinal glands; m, artery; v, 
vein; I and t, muscular coats. 100 
HOW FOOD IS DIGESTED 
the moving intestines, by breathing, and also by the suc- 
tion in the thoracic duct caused by the rushing along of 
the blood past its mouth. If a cat or dog be given a meal 
of rich milk and killed about three hours later, the 
numerous small lacteal vessels will 
appear white, because of the fat 
in them. 
The Portal System. -The portal 
system consists of a large portal 
vein, with its tributaries beginning 
in the capillaries of the intestine, 
stomach, and other abdominal 
organs, and its branches ending in 
the capillaries of the liver. The 
capillaries do not actually termi- 
nate in the liver, but are continuous 
with the capillaries forming the 
hepatic vein carrying blood away 
from the liver. Through this 
portal system all the food except 
the fats are transported from the 
villi to the liver. 
How Food passes through the 
Intestinal Wall. - Since the ali- 
mentary canal is merely a tube 
through the body, food while in it is not within the body 
where it can be used by the tissues. The final product 
of digestion in the small intestine is the chyle, which 
passes into the villi by three processes: 1. osmosis, which 
is the tendency of two liquids of different density sepa- 
rated by a membrane to mix; 2. filtration, which is the 
Fig. 64. - Diagram showing 
how the food reaches the 
heart to be sent with the 
blood to all parts of the body. FOOD PASSING THROUGH THE INTESTINAL WALL 
101 
forcing of a liquid through a membrane by pressure 
such as would occur when the muscular walls of the 
intestine contract; 3. imbibition, which is the prop- 
erty possessed by a cell of drinking in a liquid in 
contact with it, somewhat as a sponge absorbs water. 
Osmosis may be shown with the egg experiment (Fig. 
66). By cracking the shell on the large end of an egg 
it may be removed with- 
out breaking the thin 
skin beneath. Through 
a hole made in the small 
end of the egg a knife 
blade may be thrust 
down to pierce the mem- 
brane around the yolk. 
A glass tube is then to 
be pushed through the 
small end into the yolk, 
and the tube firmly 
cemented to the shell 
with paraffin or sealing 
wax melted in place with a hot nail. The egg is then 
placed tube up in a glass of water, and propped up 
with a stick so as to be only half immersed. In less 
than an hour enough water will have passed through 
into the egg to force the yolk far up in the glass 
tube, but none of the proteid of the egg will have 
been pushed through the membrane into the water, 
because proteids must be acted on by the digestive juices 
before they can pass through a membrane. Some of the 
salt in the egg will have passed out into the water. 
Fig. 65. - Part of the intestine, showing the 
veins taking the food from the villi to 
the liver. 102 
HOW FOOD IS DIGESTED 
How the Body uses Proteids and Carbohydrates. - Most 
of the proteids are used in rebuilding the worn-out tissues 
of the body, but some may be oxidized to produce heat. 
It is possible for a proteid to be changed into fat. The 
carbohydrates, before entering the 
blood, are all changed into sugar, 
which passes through the villi and 
veins to the liver. Here one part of 
it is changed into animal starch, called 
glycogen, and is retained until the 
cells of the body call for it. A 
second part of the sugar is carried 
to the muscles, and stored, while a 
third part circulates in the blood, and 
combines with oxygen to make heat. 
As oxygen combines with sugar more 
readily than with proteids, the sugar 
is used for heat and energy first, thus 
leaving the proteids for muscle re- 
pair. 
Glycogen. - The form in which 
plants store up food is plant starch, 
as seen in the potato. Glycogen, or 
animal starch, is one form in which 
food is stored for use within an 
animal. After a meal rich in car- 
bohydrates nearly ten per cent of the liver may con- 
sist of glycogen. After a period of rest one per cent of 
a muscle consists of glycogen, which is completely used 
up by an hour's exercise. An impulse sent through 
the nerve to the muscle causes the oxygen from the 
Faj. 66. -Egg experi- 
ment, showing os- 
mosis. The shell is 
removed from the 
egg at m so as not 
to break the mem- 
brane lying close 
within it. a, glass 
tube; p, paraffin; 
e, height to which 
the contents of the 
egg were forced in 
an hour. HOW THE BODY USES FATS 
103 
blood to unite with the gly- 
cogen to produce the con- 
traction of the muscle. It is 
the starches and the sugars, 
therefore, that furnish the 
energy-making stuff for a 
workingman. 
How the Body uses Fats 
Fats pass into the villi in the 
form of fatty acids, soaps, and 
glycerin. These products then 
unite at once to form fat, 
which, by the lacteals and 
thoracic duct, is taken into 
the veins in the neck and 
thence to the heart (Fig. 64). 
From here it is sent with the 
blood to all parts of the body, 
where it is oxidized. This 
oxidation, or burning, makes 
heat to keep the body warm. 
It is for this reason that 
people in cold climates con- 
sume oils and much fat meat. 
When more fat than is neces- 
sary to furnish the required 
heat and energy reaches the 
tissues, it is stored in the 
connective-tissue cells to form 
the fat of the body. If 
too little food is taken at 
Fig. 67. - Connective-tissue cells 
changing to fat cells, a, fat pass- 
ing from the blood vessel to the 
cells; b, where the fat forms two 
or three globules of oil in each 
cell; c, cells largely filled by a 
single oil globule. 104 
HOW FOOD IS DIGESTED 
any time, this stored-up fat is used to provide heat and 
energy. 
How to make the Body Fat- Some people are always fat, 
whether they eat little or much. In some cases, however, 
the amount of fat in the body can be controlled by diet 
and exercise. The fact that the eating of fat makes body 
fat has been shown by feeding a dog with mutton fat for 
a week, at the end of which time much mutton fat was 
found deposited in his tissues. That the carbohydrates 
are greater fat formers than fat itself has also been 
clearly demonstrated by feeding experiments. In order 
to become fleshy, therefore, one should eat a great deal of 
carbohydrate food, considerable fat, and enough proteid 
to take the place of the tissue waste. Rich milk, rice, 
potatoes, fat meat, olive oil, oatmeal, and soft-boiled eggs 
form a diet that will enable some persons to gain a pound 
or two weekly. An hour or more of daily exercise and 
ten hours of sleep in the open air are also of great help in 
increasing the body weight. 
One who is too fat should live largely on lean meat, 
fish, fruit, and salads, and take plenty of exercise. No 
medicines advertised to make one fat or lean are of any 
value, and they sometimes produce serious results. The 
fat retained in the body is stored in the connective-tissue 
cells. These are named fat cells when most of their 
contents consist of fat or oil. 
Alcoholic drinks tend to make the body fat, because 
alcohol injures the cells producing oxidation. The worn- 
out cells are not burned up and cast out in the excretions 
as they should be in health, but become fatty and hinder 
the work of the organs. SUGGESTIONS FOR THE TEACHER 
105 
Questions 
1. Where are ferments produced and what is. their use? 2. How 
does saliva affect food ? 3. Why should food be well chewed ? 
4. Give five points relating to the odor of food. 5. Why is the chew- 
ing of gum and tobacco generally harmful ? 6. Explain the produc- 
tion of the gastric juice. 7. Describe the movements of the stomach. 
8. Name the three foods most quickly digested. 9. Name the three 
foods requiring the longest time for digestion. 10. What frequently 
causes dyspepsia ? 11. In what one part of the alimentary canal are 
all kinds of foods partly digested ? 12. Describe the action of the 
pancreatic juice. 13. Of what use is the bile? 14. Why and how 
do the intestines move ? 15. How is the food absorbed from the intes- 
tines? 16. Give the use of the lacteals. 17. Describe the portal 
system. 18. For what purpose does the body use lean meat ? 19. Of 
what use are starches and sugars? 20. Explain the use of fats in the 
body. 
Suggestions for the Teacher 
1. Ask one of the boys to secure from the slaughterhouse a small 
piece of intestine or stomach. On the cut edge of this may be seen 
the mucous coat, containing the glands, and the muscular coat, produc- 
ing the movements of the digestive organs. The villi are clearly seen 
only in the intestine of a dog or cat. 
2. Ask some of the pupils to try the egg experiment, as showm in 
Figure 66. XI. THE BLOOD 
Parts. - The blood is composed of a colorless liquid, 
the plasma, in which float millions of round, platelike or 
cup-shaped cells called corpuscles. These are two kinds, 
the one being red and 500 times as 
numerous' as the other, which are white. 
It is the presence of the red corpuscles 
which gives the color to the blood. 
The Red Corpuscles. - These form 
almost half of the weight of the blood. 
About 25,000,000 are present in every 
drop of blood as large as the head of a 
pin. They are easily seen by examining 
with the high power of the microscope 
a smear of blood made by placing a drop 
on a glass slide and immediately drawing 
over it the smooth end of another slide 
held obliquely to the first. 
Hemoglobin, the red coloring matter, 
is the most important part of the corpus- 
cle. The iron contained in the hemoglobin enables it 
to carry oxygen from the lungs to supply the tissues 
in all regions of the body. The red corpuscles also 
transport about half of the carbon dioxide from the 
tissues back to the lungs to be cast out. 
Fig. 68. - A test tube 
of blood, showing 
relative amounts of 
plasma, p, and cor- 
puscles, c. 
106 WHITE BLOOD CORPUSCLES 
107 
White Blood Corpuscles. - There is only one white 
blood cell to 500 red ones, and as it is colorless, it is 
not easily seen under 
the microscope unless 
stained with some dye. 
Some of the white cells 
are of the same size as 
the red ones, while 
others are more than 
twice as large. Many 
are capable of changing 
their shape very much 
after the manner of a 
little one-celled animal 
living in stagnant water 
and called the amoeba. 
This amceba-like or amoe- 
boid motion of the white cells may be seen by examining 
with the microscope a drop of the fluid taken from a 
blister. This liquid is 
the blood plasma, with 
many white corpuscles 
which have leaked out 
of the minute blood 
vessels. The white 
cells creep through be. 
tween the cells forming 
the walls of the capil- 
laries in all parts of 
the body. In healthy tissues they are taken up by the 
lymph vessels to be carried back to the veins. 
Fig. 69. - One white corpuscle and several 
red ones, photographed through the mi- 
croscope. 
Fig. 70. - White blood corpuscles, photo- 
graphed to show their form when crawling. 108 
THE BLOOD 
Wherever there is inflamed or diseased tissue, the white 
sells are attracted in great numbers. They creep out of 
the capillaries, and 
often large quanti- 
ties are destroyed 
and then they form 
most of the pus, or 
white matter, pres- 
ent in a boil or other 
suppuration. The 
white corpuscles 
have three uses: 
they aid the villi in absorbing certain food from the intestine; 
they have some part 
in causing the clot- 
ting of the blood; 
and they help pro- 
tect the body from 
harmful germs by 
devouring them. 
Birth and Death 
of Corpuscles. - 
Since the coloring 
matter of the bile 
is derived from the 
dead red cells, and 
since millions of 
white corpuscles are 
being killed wher- 
ever pus is formed, 
there must be some 
Fig. 71. - Diagram of a capillary network, show- 
ing the white corpuscles crawling through the 
capillaries to eat the bacteria, causing aboil at m. 
Fig. 72. - Diagram of the capillaries uniting an 
artery and vein. The plasma is passing through 
the walls of the capillaries to nourish the body 
cells, after which some of it enters the mouths 
of the lymph vessels and the rest returns to the 
the capillaries. Arrows show the direction of 
the circulation. THE USE OF BLOOD 
109 
means by which new blood corpuscles are rapidly devel- 
oped. The chief place of their birth has been found to be 
the red marrow contained in the ends of all the long bones, 
and abundant throughout the interior of the other bones. 
The small white corpuscles are derived from the division 
of cells in the several hundred lymph glands scattered 
throughout the body. Experiments on animals, in 
which millions of red corpuscles are lost by bleeding, 
show that they are regained so rapidly that more than 
a thousand must be formed every minute. 
The Plasma. - This is the colorless part of the blood 
which is constantly filtering out of the capillaries for the 
purpose of supplying the tissues with food. While bath- 
ing these it not only gives to them nourishment, but 
receives from them ashes or waste products, such as car- 
bon dioxide and that which becomes the chief solid in the 
urine. Then these waste products pass through the cap- 
illary wall into the blood, but the escaped plasma, which 
is not able to return to the capillaries, is now called lymph. 
Nine tenths of blood plasma is water. 
The Lymph. - This is the blood plasma filtered and dif- 
fused from its vessels. It occurs in all spaces within the 
body cavity and in the crevices between the tissues. It con- 
tains numerous white blood corpuscles. Its purpose is to 
convey material to the tissues from the blood, and to the 
blood from the tissues. It is carried back into the blood sys- 
tem by thousands of microscopic vessels uniting into larger 
and larger vessels, of which two enter the veins in the neck. 
The Use of Blood. -The blood performs four functions : 
It regulates the temperature of the body, transfers food 
to the tissues, bears oxygen to the tissues, and transports 110 
THE BLOOD 
waste matter from all regions to the organs casting it 
out of the body. The heat formed by the active cells 
in the deep tissue is carried by the blood to the minute 
vessels near the surface of the body, where the cool air 
and the evaporating perspiration have a cooling effect. 
The food is carried in the plasma of the blood to all 
parts of the body. A muscle cannot contract without 
oxygen, the vital organs refuse to act in the absence of 
oxygen, and the brain refuses to give 
orders if oxygen is shut off only for a 
minute. Therefore the distribution of 
this element by the blood is of prime 
importance. Life could not continue 
without the transportation of the waste 
products to the lungs, kidneys, and 
sweat glands for elimination. 
The Clotting of Blood. - As soon as 
blood escapes from the vessels, it under- 
goes a change and becomes like jelly. 
This is called a clot. It is composed of all the cor- 
puscles entangled in a white fibrous substance known 
as fibrin. The chief part of the plasma, much of 
which at first is contained in the clot, gradually works 
out, and appears around it as a yellowish fluid named 
serum. If blood is secured in a tall vessel from the 
butcher shop and placed twenty-four hours in a cool room, 
the serum will appear on top of the clot. There is no 
fibrin in the blood while in the body, but there is a 
proteid called fibrinogen, from which fibrin is formed in 
shed blood through the agency of a ferment not active 
in the blood vessels. 
Fig. 73. - A glass of 
blood, showing the 
clot, c, floating in 
the serum almost 
filling the vessel. PURE AND IMPURE BLOOD 
111 
The fibrin may be easily separated from the clot by 
putting clotted blood into a muslin bag or enveloping it in 
a handkerchief, and then kneading or squeezing it five or 
ten minutes under water. The clotting of blood is very 
important, as by this means nature often stops the flow 
from a wound. 
The Amount of Blood. - A full-grown person contains 
about six quarts of blood. Half of this quantity may 
be lost through a break in the vessels without causing 
death. When one has suffered the loss of much blood, 
the lack of fluid in the vessels is remedied by injecting a 
normal salt solution (7 parts of common salt to 1000 
parts of water) into the veins. If pure water were used, 
many of the red blood cells would be destroyed, and the 
blood of another animal cannot be used because it like- 
wise causes the red cells to go to pieces. 
Pure and Impure Blood. - The blood carried in the 
arteries, except the artery leading to the lungs, is spoken 
of as pure or arterial blood because it contains very little 
carbon dioxide. It has a rich red color, while the blood 
of the veins, called venous blood, is of a bluish hue, as seen 
through the skin in the veins of the wrist. This color 
is due to the carbon dioxide gathered from the tissues. 
People who feel weak and languid or have pimples on the 
face are sometimes told that their blood is bad. What- 
ever the condition of the blood may be, it is due to the 
healthy or unhealthy state of the organs of the body, be- 
cause the blood is made by the tissues and the impurities 
are removed only by certain organs. Therefore, when one 
is said to have bad blood, it means that the cells of some 
organ are failing to perform their task properly. 112 
THE BLOOD 
Bacteria in the Blood. - When the body is in health, no 
bacteria are present in the blood except just after a meal. 
The germs may gain access to the blood with the food 
taken in by the villi. This is a common occurrence in 
children. The bacteria present in the food of young 
guinea pigs have been found to pass into the blood in 
large numbers, while in older guinea pigs very few reach 
the blood. It is therefore important that one should not 
eat food containing disease germs, such as those of tuber- 
culosis, sometimes found in milk and butter. 
Harmful germs may get into the blood and yet no dis- 
ease result, because the plasma has the power to destroy 
a few bacteria of almost any kind. This power may be 
greatly increased by the use of vaccines and antitoxins, so 
helpful in preventing smallpox, hydrophobia, diphtheria, 
and tetanus. The white corpuscles also destroy germs. 
The Spleen. - The spleen is a dark red body somewhat 
oval in shape and much flattened, so that it is an inch 
thick and four inches broad by five inches long. It lies 
on the left side of the body in the abdominal cavity, and 
is partly covered by the ribs. Its function is not known. 
It enlarges very much a few hours after digestion, and 
probably has something to do in making a ferment to 
aid the pancreatic juice in digestion. It has no duct, 
and whatever its product is, it must go directly into the 
blood. In structure it is like the lymphatic glands, and 
it probably has a share in making some of the small white 
blood corpuscles. 
The Thyroid Gland. - This is a flat two-lobed body 
weighing two ounces. It lies in front of the trachea below 
Adam's apple. It has no duct. A dog from which the SUGGESTIONS FOR THE TEACHER 
113 
thyroid has been removed is able to live only three weeks. 
Persons from whom the thyroids have been removed on 
account of disease are kept alive by eating the thyroids of 
calves or pigs, or by taking an extract prepared from 
these glands. The exact use of the thyroid gland is not 
known, but its secretion is turned directly into the blood 
and has a marked effect on the mind as well as the general 
development of the body. 
Questions 
1. Name the parts of the blood. 2. Give five facts about red blood 
corpuscles. 3. What service do the white blood corpuscles render? 
4. Where are the blood corpuscles formed? 5. How fast may corpus- 
cles be formed? 6. What is the nature and use of blood plasma? 
7. State what you know about lymph. 8. What are the chief functions 
of the blood? 9. When does blood clot? 10. How much blood does 
the body contain? 11. How does arterial blood differ from venous 
blood ? 12. Give some facts in reference to bacteria in the blood. 
13. Point out the location of the spleen on your body. 14. State the 
probable use of the spleen. 15. Give the function of the thyroid 
gland. 
Suggestions for the Teacher 
1. If possible, borrow a microscope and ask the lender to prepare 
a slide of blood so that you may show the corpuscles to the children. 
2. Ask the class to observe the blood in the veins of the wrist, and 
explain why it appears blue. 
DAV. PHYS. 8 XII. THE CIRCULATORY SYSTEM 
This system consists of the heart, arteries, capillaries, 
veins, and lymphatics. The heart propels the blood, the 
arteries carry it from 
the heart, the veins 
and lymphatics re- 
turn it to the heart, 
and the capillaries 
connect the arteries 
with the veins. . 
The Location of 
the Heart. - The 
heart, composed of 
involuntary muscle, 
is shaped like an egg 
and has its apex, 
or pointed end, di- 
rected downward 
and toward the left 
side of the body. 
It is surrounded by 
a tough membrane, 
the pericardium, con- 
taining half a tea- 
cupful of lymphlike 
fluid. This protects the heart from injury. It lies 
between the lungs and almost in the center of the 
Fig. 74. - Organs of the chest. The front part 
of the pericardium is cut away. The lungs 
have been slightly separated, a, right auricle; 
b, diaphragm; e, left auricle; h, vena cava; 
k, kidney; n, right ventricle; p, artery to the 
lungs; r, one of the several cut-off ribs; t, 
vena cava; u, arteries to head and arms; v, 
left ventricle. 
114 THE CAVITIES OF THE HEART 
115 
thoracic cavity, where it is held in place by the great 
blood vessels attached at the upper and back part, and 
also by fibrous tissue connecting the 
pericardium with the breastbone. 
The Cavities of the Heart. - 
The heart contains four cavities, 
the two upper and smaller ones 
being called auricles, while the two 
Fig. 75. -The human heart 
from in front, a, aorta; 
ao, aorta descending back 
of the heart; c,venacava; 
ca, carotid arteries to the 
head; e, esophagus; i, 
left auricle; m, arteries 
to the arm; p, pulmonary 
artery; r, right auricle; 
t, left ventricle; tr, tra- 
chea or windpipe. 
Fig. 76. - Diagram showing the 
front half of the heart cut away. 
a, aorta; I, arteries to the lungs; 
la, left auricle; Iv, left ventricle; 
m, tricuspid valve open; n, bi- 
cuspid or mitral valve closed; 
p and r, veins from the lungs; 
ra, right auricle; rv, right ven- 
tricle; v, vena cava. Arrows 
show direction of circulation. 
lower are named ventricles (Fig. 74). The auricles are thin- 
walled sacs which receive the blood from all parts of the 
body and pass it to the thick-walled ventricles, which send 116 
THE CIRCULATORY SYSTEM 
it out to the tissues. The cavities on the left side of the 
heart are known as the left auricle and left ventricle, the 
other two being termed the right auricle and right ven- 
tricle. The muscular walls of the left ventricle are more 
than twice as thick as those of the right, because the one 
sends the blood all 
over the body, while 
the other sends it 
only to the lungs. 
The two openings 
into the right auricle 
are the ascending 
vena cava and the 
descending vena 
cava. There is no 
opening between 
the two auricles, 
but a large aperture 
guarded by valves 
permits the blood 
to pass from an 
auricle to the ven- 
tricle below it. 
Four pulmonary 
veins open into the left auricle and bring the pure blood from 
the lungs. There is only one artery leading from each ven- 
tricle. From the left ventricle the aorta,& great artery larger 
than the thumb, carries the blood to the body. From the 
right ventricle the pulmonary artery extends to the lungs. 
The Valves of the Heart. - In order that the blood may 
pas§ in ojijy one direction,, through the heart, four sets of 
Fig. 77. - Calf's heart cut open, a and ao, 
arteries; c and o, parts of tricuspid valve; 
v, right ventricle; e, cut wall; n, cut wall 
held up by a stick. THE VALVES OF THE HEART 
117 
valves are present. Between the right auricle and ven- 
tricle is the tricuspid valve, composed of three membranous 
flaps whose free edges 
are prevented from 
being pushed back into 
the auricle by the sev- 
eral tough cords, an inch 
or two long, extending 
from them to the walls 
of the ventricles (Fig. 
77). The free margins 
of this valve, hanging 
down into the ventricle, 
permit the blood to pass 
from the auricle to the 
ventricle, which contracts and presses the blood against 
the lower surface of the flaps. This pushes them up and 
together, thus closing the aperture 
so that the blood must pass out of 
the pulmonary artery. 
The mitral or bicuspid valve 
guards the passage between the 
left auricle and left ventricle. 
It works in the same way and 
exhibits the same structure as the 
tricuspid valve, except there are 
only two membranous flaps. 
In the mouth of the artery 
leading from each ventricle are three half-moon-shaped 
pieces of membrane attached by their convex sides only 
so that their free margins may be pushed out to prevent 
Fig. 78. - The pulmonary artery cut open 
to show the semilunar valves, 1, 2, 3. rv, 
right ventricle. 
Fig. 79.-The aorta cut off 
at the heart, showing the 
three somewhat triangular 
semilunar valves closed. 118 
THE CIRCULATORY SYSTEM 
the backward flow of the 
blood. On account of the 
shape of the parts, these valves 
are called semilunar (Fig. 79). 
How the Heart Works. - 
The auricles are filled with 
blood at the same time, and 
then they contract and push 
the blood into the ventricles, 
which at once contract to 
send the blood out to the 
arteries. Then there is a 
pause of about a half second, 
while the heart is filling, be- 
fore another contraction takes 
place. The contraction of 
any part of the heart is called 
a systole, and the pushing out 
of the walls while being filled 
is the diastole. The alternate 
contraction and expansion of 
the walls of the heart con- 
stitute the heart beat, which 
occurs about 75 times per 
minute in the adult and 140 
times in the young child. 
Exercise and the Heart. - 
The heart must beat faster 
during exercise in order to 
drive through the lungs a 
larger volume of blood to 
Fig. 80. - The chief blood vessels 
of the human body. On the left 
arm and leg the vessels are shown 
as they appear just beneath the 
skin. The veins are in black. 
a, location of the heart; b, brach- 
ial artery and veins; c, carotid 
artery; f, femoral vessels; i, 
iliac vessels; j, jugular vein; 
I, pulmonary vessels to the lungs; 
ra, radial vessels; t, anterior 
tibial; u, ulnar vessels. HEART DISEASE 
119 
secure enough oxygen to supply the demand of the muscles. 
Every muscular contraction uses up oxygen, and therefore 
the greater the exercise, the greater is the amount of 
oxygen needed. This need of the muscles is carried by 
the nerves to the spinal cord, where the proper cells send 
the order to the heart to work 
more rapidly. Prolonged and 
severe exercise, such as bicycle 
riding and running, if indulged 
in frequently, sometimes causes 
enlargement of the heart, re- 
sulting in serious trouble. 
The Pulse. - The pulse is 
the wave of blood produced in 
the arteries by the heart beat. 
It may be felt wherever an 
artery runs near the surface, as 
on the thumb side of the wrist 
or just in front of the ear. 
Sickness usually affects the 
heart beat, because poisons are 
being generated in the body, 
and they act on the nerves controlling the heart. On this 
account, the frequency and strength of the pulse furnish 
the doctor with valuable information concerning the 
bodily health. 
Heart Disease. - Some form of heart disease is a com- 
mon ailment in people over sixty years of age, and occa- 
sionally in those much younger. The census report of 
1906 shows that more than 100,000 people died of heart 
disease in that year in the United States. Fatty degen- 
Fig. 81. - Small artery. Mag- 
nified. Part of the coats re- 
moved at one end to show 
structure. 120 
THE CIRCULATORY SYSTEM 
eration of the heart, caused by the muscle being changed 
to fat, is likely to affect fleshy persons, and is especially 
prevalent among beer drinkers. 
A most serious affection of the heart is the inability of 
the valves to prevent the blood from flowing backward. 
Disease of the valves often 
results from rheumatism, 
scarlet fever, and diph- 
theria. The medicines 
much advertised to cure 
heart ailments are of no 
use, and should never be 
taken by those who want 
to live. A physician 
should be consulted. The 
very rapid and irregular 
beating of the heart is 
spoken of as palpitation 
of the heart. It is fre- 
quently caused by some 
digestive trouble in the 
stomach. 
The Arteries. - The 
vessels carrying the blood 
away from the heart are 
the arteries. Prior to the 
seventeenth century they were thought to conduct air, 
hence the name. They are empty after death, and the 
blood is found in the heart and veins. The walls of the 
arteries are much thicker and more elastic than those of 
the veins. They are made of elastic fibers, other con- 
Fig. 82. - Microscope arranged to see 
the blood circulating in the tail of a 
tadpole. THE CAPILLARIES 
121 
nective tissue, involuntary muscle cells, and a layer of 
flat epithelial cells within. 
The chief artery of the trunk is the aorta, which leads 
from the left ventricle, and at once forms an arch to pass 
behind the heart down through the body cavity in front 
of the backbone. It 
gives off more than 
thirty branches to the 
trunk and the internal 
organs. In the lower 
part of the abdominal 
cavity it divides into 
a right iliac and a left 
iliac to supply the legs 
with blood. From the 
arch of the aorta three 
branches are given off 
to supply the arms, 
neck, and head. The 
large artery on either 
side of the windpipe is the carotid, taking blood to the 
head and brain. 
The pulmonary artery is a large vessel leading from 
the right ventricle to the lungs. This is the only artery 
transporting venous blood. All the arteries branch again 
and again, like the branches of a tree, until the little 
vessels are too small to be seen with the naked eye. 
The Capillaries. - The capillaries are the smallest blood 
vessels of the body and serve to connect the arteries with 
the veins. A capillary is about as long as the diameter 
of an ordinary pin, while its breadth is one fifth that of 
Fig. 83. - Arteries dividing into capillaries 
in a muscle. Photographed through the 
microscope. THE CIRCULATORY SYSTEM 
122 
a hair. From each terminal minute artery branch several 
capillaries, which reunite so as to form a network in all 
regions of the body. These vessels are so numerous that 
a needle cannot penetrate the flesh without piercing some. 
The walls of the capillaries are made of a single layer 
of epithelium, so thin that the oxygen and food in the 
blood may easily pass through while the waste of the 
tissues enters the blood. The capillaries with the blood 
moving in them may be easily seen in the 
tail of a tadpole or a small fish on a large 
glass slip put under the low power of the 
microscope (Fig. 82). 
Use of the Capillaries. - Arteries and 
veins merely conduct blood. The capil- 
laries perform three functions : they con- 
nect the arteries with the veins ; they 
allow the oxygen, some white cells, and 
some plasma to escape among the tissues; 
and they let waste matter pass from the 
tissues into the blood. Sufficient time is afforded for 
the exchange of these elements, as the blood flows very 
slowly through the capillaries. 
The Veins.-The walls of the veins are much thinner 
than those of the arteries, but have a similar structure. 
They carry the blood to the auricles of the heart. The 
venous blood differs from the arterial in containing little 
oxygen and much carbon dioxide. The pulmonary veins, 
leading from the lungs to the heart, convey oxygenated 
blood. The two great veins of the trunk are the descend- 
ing vena cava, bringing the blood from the head, neck, and 
arms, and the ascending vena cava, returning blood from 
Fig. 84. - Vein 
cut open to show 
valves, i, free 
edge of valve v. LOCATION OF THE VESSELS 
123 
the trunk, the internal organs, and the legs. The large 
vein on either side of the neck is the jugular. 
Within the veins, especially those of the extremities, 
are numerous valves permitting the blood to pass in only 
one direction. The arteries, except at their openings from 
the heart, do not have valves. By breathing and move- 
ment of the muscles 
of the trunk and 
limbs, the blood 
vessels are pressed 
on, and their con- 
tents are then 
forced toward the 
heart, because the 
valves of the veins 
permit the blood to 
flow in only one 
direction. 
How the Blood 
Vessels are Named. 
- The names of the arteries and veins, as well as the 
nerves supplying an organ, are usually derived from the 
Latin name of the organ. Brachial is the name of the 
large vessels in the arm, renal applies to the vessels of 
the kidneys, hepatic to those of the liver, cardiac to those 
of the heart, mesenteric to those of the intestines, radial 
to those along the radius, and femoral to those along 
the femur. 
Location of the Vessels. - Most of the arteries lie in 
protected places deep beneath the muscles. In the 
forearm and also in the leg below the knee, two or three 
Fig. 85. - Regions where large arteries lie near 
the skin. 124 
THE CIRCULATORY SYSTEM 
routes are provided for the blood to and from the ex- 
tremities, as may be seen in the figures. The brain is 
a most important organ, and there are four different 
channels provided 
for carrying .to it 
the blood from the 
large vessels in the 
chest. 
In the limbs the 
chief veins, arteries, 
and nerves lie close 
together and usually 
near the bone. An- 
other set of veins, 
known as superficial, 
lie just beneath the 
skin. These may 
be seen plainly in 
the arm. 
Lymph Vessels, 
or Lymphatics.- 
There are numerous 
chinks and crevices 
among the tissues 
called lymph spaces. 
Large lymph spaces exist within the serous membranes of 
the thoracic and abdominal cavities. From all of these 
spaces the lymph is conveyed by minute vessels called 
lymph capillaries. They form a thick network in many 
parts of the body. They unite to form larger vessels, and 
these combine tn form trunks, of which there are several 
Fig. 86. - a is bluing injected through the skin on 
a cat's ear, to show how from this lymph space 
the many tiny lymph vessels take up the blue 
material and pass it on to larger vessels. LYMPH VESSELS, OR LYMPHATICS 
125 
extending up each limb and downward from the head. 
I hose from both legs, the left side of the body, neck, 
head, and left arm join the left thoracic duct. This is 
about the size of a lead pencil, and extends from the lum- 
bar region along the back side of the body cavity to unite 
with the large vein in 
the neck. The trunks 
of the right side of the 
body, right arm, and 
right side of head and 
neck join the very short 
duct emptying into a 
vein on this side of the 
neck. 
Vessels also lead 
from the internal organs 
to the thoracic duct. 
Those extending from 
the small intestine are 
called lacteals, because 
in addition to the lymph 
they convey the fatty 
portions of the food, 
appearing white like milk. The purpose of the lymph 
vessels is to return to the veins that part of the blood 
which escapes from the blood capillaries. 
Any substance injected beneath the skin will be taken 
up by the lymph vessels and rapidly distributed over the 
system. Vaccine germs and the poison from a snake bite 
are usually gathered up by the lymphatics, as are also the 
medicines administered by hypodermic injections. 
Fig. 87. - The lymphatics, or lymph ves- 
sels. The dark spots are lymph glands, 
or nodes, lac, lacteals; rc, thoracic duct. 126 
THE CIRCULATORY SYSTEM 
Lymph Glands, or Nodes. - These are small, round, oval, 
or oblong bodies, some of which are no larger than the 
head of a pin, while others are a half inch in diameter. 
They occur most abundantly in the region of the neck and 
in a fold of the peritoneum, which holds the intestine in 
place. Other groups are found where the limbs join the 
body and behind the lungs. 
No lymph is turned into the veins without first passing 
through one or more lymph glands, which tend to with- 
hold the bacteria or other harmful substances from enter- 
Fig. 88. - Lymph vessels of the finger. 
ing the blood. A boil or other inflammation on the arm 
may cause many germs and so much poison to be carried to 
the glands in the armpit that they enlarge and become 
very tender in their effort to destroy these enemies to 
health. The lymph nodes are also of use in making 
some of the white blood corpuscles. 
Cause of the Flow of the Lymph. - Lymph vessels filled 
with colored fluid may be recognized by their knotted ap- 
pearance, due to the numerous valves which permit the 
lymph to flow in only one direction. The pressure of the 
lymph in the spaces about the lymph capillaries tends to 
force the fluid along in the vessels, and the pressing of a 
contracted muscle or even the filling of the lungs with 
air squeezes the lymph vessels and, on account of the THE COURSE OF THE BLOOD 
127 
valves, moves the contents toward the veins. One of the 
greatest benefits derived from exercise is the freeing of 
the tissues from the lymph with its collected impurities. 
Massage produces somewhat the same effect as exercise. 
The Course of the Blood. -The movement of the blood is 
from the left ventricle 
to the arteries of the 
body, then through the 
capillaries to the veins 
and lymphatics return- 
ing it to the right 
auricle. From here it 
goes to the right ven- 
tricle forcing it to the 
pulmonary artery into 
the lungs, where it 
passes by capillaries to 
the pulmonary veins 
conveying it to the 
left auricle opening 
into the left ventricle. 
The word v-a-v-a-c is 
an aid in remembering 
that the blood passes 
from veins to auricles 
and thence to ventricles forcing it through arteries to 
capillaries. 
The passage of the blood around through the lungs to 
the left auricle is called the pulmonary circulation, while 
its flow through the other parts of the body is known as 
the systemic circulation. A part of the systemic circula 
Fig. 89. - Lymph vessels of the head. Note 
more than a score of lymph nodes in the 
neck. (From the " Reference Handbook 
of Medical Sciences.") 128 
THE CIRCULATORY SYSTEM 
tion is called the portal circulation. This consists of the 
flow of blood from the capillaries and veins of the ab- 
dominal viscera into the portal vein and its branches 
dividing into capillaries within the liver. 
Rate at which the Blood Flows.-The rapidity with 
which the blood travels has been determined by experi- 
ments on the lower 
animals. It passes 
through the largest 
arteries ten times as 
fast as through the 
very small ones, and 
flows less than one five- 
hundredth as fast in 
the capillaries as in the 
aorta. In the carotid 
artery of the horse it 
flows one foot per 
second, and it is esti- 
mated that it requires 
one second to pass 
through the entire 
length of a capillary. 
Regulation of Blood 
Flow. - Since more 
oxygen is required during exercise, the blood must flow' 
more rapidly to and from the lungs to supply the demand. 
The heart is made to beat more quickly by an order 
sent to it by nerve cells. These cells have been stimu- 
lated by the oxygen-hungry muscles sending a notice 
of their wants. 
Fig. 90. - Method of stopping the flow of 
hlood from a cut by twisting tight a 
handkerchief under which a piece of wood 
has been thrust over the brachial artery. CIRCULATION AND HEALTH 
129 
Hemorrhage, or Bleeding.- A blow on the skin often in- 
jures the small blood vessels, so that the red cells escape 
or the vessels become distended with blood, giving the 
place a bluish black appearance. If the skin and vessels 
are broken, the blood pours out, and this is called a hemor- 
rhage. 
If an artery is cut, the blood issues in spurts corres- 
ponding to the heart beats, while from a vein the flow is 
steady. Unless the vessel is large, a clot will soon form 
and check the flow. The hand or a clean cloth held over 
the cut helps very much in the formation of a clot. The 
flow from an artery may be checked by pressing tightly 
on the vessel on the side of the wound toward the heart. 
A handkerchief or cord should be tied loosely around the 
limb between the cut and the heart, and where the vessel 
lies nearest to the skin. A stick or folded cloth is then 
to be slipped under the ligature and over the vessel, and 
the ligature then tightened by twisting it with a stick. 
To stop the bleeding from a vein, the pressure or ligature 
should be applied on the side of the wound away from the 
heart. 
A quart of blood may be lost by an adult without dan- 
ger, and twice that amount may escape without causing 
death. 
Circulation and Health.-Any wearing apparel which 
hinders the free circulation of the blood should not be 
used. Garters that encircle the leg and tight clothing 
about the waist are detrimental to health. When lymph 
collects in the tissue spaces faster than it is removed, a 
disease known as dropsy results. Exercise for an hour 
daily is necessary to promote circulation in health. 
DAV. PHYS. 9 130 
THE CIRCULATORY SYSTEM 
Alcohol and the Circulatory System. - A glass of beer 
or a glass of wine has a perceptible effect on the circula- 
tion. The arteries of the skin become enlarged and the 
extra blood sent to the surface produces the redness in 
the face. This is often constantly present in persons 
using alcohol daily. Since so much blood is near the 
surface, where the cold air may carry off the heat, alcohol 
in cold weather makes the body colder. A drink of 
whisky in winter may cause a man to feel warm, because 
much blood is forced into the skin, where the sense of 
heat is most acute, but a thermometer shows that the body 
throughout becomes colder. The experience of arctic 
travelers proves positively that those using alcohol in 
severe weather are the ones who soonest freeze to death. 
The investigations of the Committee of Fifty, composed 
of well-known business men and scientists, show that in 
those who drink large quantities of beer enlarged hearts 
are comparatively frequent. The use of beer is a promi- 
nent cause of fatty degeneration of the heart muscle. One 
in every sixteen patients in the hospitals of Munich dies 
from enlargement of the heart, due to the drinking of 
beer. In habitual drunkards the coats of the arteries are 
liable to become hardened, so that a little extra pressure- 
will produce a rupture. The breaking of a vessel in the 
brain often results in apoplexy or paralysis. 
The elements in the blood warding off all kinds of 
germ diseases are weakened in those using much alcoholic 
drinks, so the chances of life are greatly in favor of total 
abstainers. A recent publication of the Committee for 
the Prevention of Tuberculosis in New York states: 
" Alcoholism is admitted by all authorities to be an ini- SUGGESTIONS FOR THE TEACHER 
131 
portant factor in predisposing to tuberculosis. Liquor as 
a beverage is never useful and nearly always harmful. 
Alcoholism must be considered the greatest enemy of the 
welfare of a nation, the most frequent destroyer of family 
happiness, and certainly the most active cooperator of 
the deadly bacillus tuberculosis." 
Questions 
1. Point out the location of the heart on your own body. 2. In 
what way do the cavities of the heart differ ? 3. Describe the pulmo- 
nary veins. 4. Describe the valves of the heart. 5. Explain how the 
heart works. 6. How many times per minute does your pulse 
beat after running? Wherein do the arteries differ from the veins? 
7. Name four arteries and tell to what parts they lead the blood. 8. De- 
scribe the capillaries. 9. Name the largest vein and largest artery 
in the body. 10. According to what plan are the arteries and veins 
named? 11. Describe the largest lymph vessel. 12. How does lymph 
of the finger reach the blood system? 13. What causes the flow of 
lymph ? 14. Describe the course of the blood through the body. 
15. At what rate does the blood flow ? 16. Explain how a hemorrhage 
may be checked. 17. In what way does exercise benefit circulation ? 
18. What effect has alcohol on the blood vessels? 19. How does 
alcohol affect the heart ? 20. State the influence of alcohol on the 
blood. 
Suggestions for the Teacher 
1. Ask a boy to secure from the butcher or slaughterhouse the 
heart of a sheep, pig, or calf. Request the butcher to leave in place an 
inch or two of all vessels attached to the heart. Arteries may be dis- 
tinguished from the veins by their thickness. Note the soft, small, 
and thin-walled auricles at the top of the heart and the veins entering 
them from the back. Cut a large piece out of the front side of each 
auricle and ventricle to show the valves. Slit open the pulmonary 
artery at its junction with the heart, and observe the three semilunar 
valves. This specimen may be preserved in the formaldehyde solu- 
tion. 
2. Ask a pupil to show how to stop the flow of blood in case a large 
artery is cut in the wrist or a vein in the arm. XIII. THE RESPIRATORY SYSTEM 
The Use. -The union of oxygen with any substance 
produces heat. The burning of wood is the union of the 
oxygen of the air with the carbon of the wood. In the 
same way the body is kept warm by the union of 
breathed-in oxygen with the food or tissues in the system. 
Moreover, energy or power to act may also be produced 
by the union of oxygen with another substance, as seen 
in the locomotive, where steam is formed from water 
heated by fire. Fire is the oxidation of the fuel. The 
oxygen, uniting with the dead tissues, burns them to ashes, 
so that they may be carried out of the body. Depriving 
the brain of oxygen causes fainting or unconsciousness. 
In many worms and salamanders the oxygen needed 
passes through the thin, moist skin to the blood, while in 
all insects there are along the sides of the body several 
openings from which tubes branch like a tree among the 
tissues to convey oxygen. Oysters, fish, and many other 
creatures dwelling in the sea have gills for absorbing the 
oxygen contained in the air lying between the particles of 
the water. In the higher animals lungs are the only means 
of procuring oxygen for the system. The respiratory ap- 
paratus also serves to get clear of the carbon dioxide, which 
is a part of the ashes resulting from oxidation. Speech 
is likewise dependent upon the organs of respiration. 
The Parts. - The respiratory system consists of the 
nasal passages, the pharynx, the larynx, the trachea, and 
132 THE PHARYNX 
133 
the lungs. The nasal passages are the two channels 
within the nose. The pharynx is the irregular cavity at 
the back of the mouth. The larynx is the cartilaginous 
box at the top of the trachea, or windpipe conducting air 
to the lungs (Fig. 51). 
The Nasal Passages. - These two air channels of the 
nose are separated by the nasal septum. They open behind 
at the upper and back part of the mouth. They are lined 
with mucous membrane, in which are glands giving out a 
secretion called mucus. This is sometimes watery, as at 
the beginning of a cold, or thick and stringy, as when one 
is recovering. The mucus is of great service in preventing 
disease, as it has the power to destroy most germs. Thou- 
sands of these are caught daily on the hairlike processes, 
called cilia, sticking out from the surface of the cells. 
The numerous hairs in the passages also aid in holding 
back the germs and dust from entering the windpipe. Be- 
cause of these facts one should breathe through the 
nose and not through the mouth, which has no special 
structures for restraining the dust and germs from the 
lungs. 
The nasal duct, extending from the inner corner of the 
eye obliquely through to the nasal passages, permits the 
tears, constantly being secreted, to escape without running 
down the cheek. In case of weeping, the duct is too small 
to convey the many tears, and so they overflow. The 
nerve of smell is distributed to special cells of the mucous 
membrane in the upper part of the passages. 
The Pharynx. - This is the large cavity at the root of 
the tongue, formed by the union of the nasal passages 
and the mouth. From the front and upper part of the 134 
THE RESPIRATORY SYSTEM 
pharynx a Eustachian tube leads to either middle ear. 
From its lower part open the esophagus and larynx. On 
either side of the root of the tongue is an oval body 
nearly an inch long, called the tonsil (Fig. 91). Its use 
is not known, and 
it is often removed 
by the doctor when 
it becomes enlarged, 
as is the case in 
many children. 
The uvula is a 
small finger-like 
body hanging down 
into the pharynx 
from the soft palate 
which forms the roof 
of the back part of 
the mouth. The 
hard palate is the 
roof of the mouth in 
front of the soft pal- 
ate. Its mucous 
membrane lies 
against bone (Fig. 
51). 
The Larynx. - At the top of the windpipe is a tube 
about two inches long and an inch wide, made of two large 
pieces of cartilage and several small ones. The pro- 
jecting part of the large cartilage, the thyroid, forms 
Adam's apple, the prominence in the neck under the chin. 
The cartilages are united by membrane and muscle. 
Fig. 91.-The tongue and opening into the 
larynx, seen from above, a, opening from 
pharynx to esophagus; b, epiglottis pushed 
forward with a needle; c, tonsil; e, vocal cords, 
between which is the opening to the larynx. THE VOICE 
135 
Within the larynx is a layer of mucous membrane, whose 
surface cells have cilia projecting from them to catch and 
throw upward the germs and dust. 
The narrow, slitlike opening from the pharynx into the 
larynx is the glottis. A small, somewhat triangular lid, 
the epiglottis, has its base attached just in front of the 
glottis. A projecting fold of membrane, passing from 
before backward on either side within the upper part of 
the larynx, forms the vocal cords. 
The Vocal Cords. -These are two ligamentous folds of 
membrane, the ends of which are attached to the cartilage 
of the larynx (Fig. 91). The cords may be rendered 
more or less tense by certain muscles which may by con- 
traction move the pieces of cartilage. 
The stretching of the cords makes the passage between 
them small, so that the breathing out of air from the 
lungs causes them to vibrate and produce sounds called 
voice. When sounds are so modified by certain positions 
of the tongue, palate, teeth, and lips as to form words 
speech is produced. All animals from frogs to man have 
vocal cords, which may be easily seen by cutting a 
larynx of a calf or pig lengthwise from before back- 
ward. However, no animals except man can talk because 
they do not know how to use the organs of the mouth and 
throat in the right way to form the proper sounds. 
The Voice. -The vocal cords are longer in men than in 
women, and therefore the women have a more shrill high 
voice. The longer the cords, the less frequently they 
vibrate when the air rushes out between them. The 
pitch of the voice depends upon the number of vibrations 
per second. The lowest bass note is produced by 44 136 
THE RESPIRATORY SYSTEM 
vibrations per second, while the highest note, five and a 
half octaves above, is made by 1980 vibrations per second. 
The loudness of sound depends largely upon the force 
with which the air is expelled through the larynx. 
In whispering, the opening between the vocal cords is 
so wide that the air passes 
out without causing any 
vibration, and the current 
is checked at intervals and 
modified by the lips, tongue, 
and teeth. 
The quality of the voice, 
which differs so much in 
singers and speakers, de- 
pends not only on the con- 
dition of the vocal cords, but 
also upon the shape of the 
mouth, pharynx, and larynx, 
and their modification by 
the contraction of certain 
muscles. The nasal twang 
is produced when the nasal 
passages are partly closed by a cold or by a growth of 
tissue called adenoids. Hoarseness is due to a swelling 
of the cords, resulting from the blood and lymph collect- 
ing in them because of a cold or too long-continued use. 
It is important that every one should cultivate a smooth 
and pleasant tone of voice and avoid making harsh and rasp- 
ing sounds. The mouth should be well opened in speaking, 
the soft palate elevated, and the lips moved with firmness. 
Some years ago deaf people who were unable to talk 
Fig. 92.-Human lungs, h, heart; 
t, trachea. THE TRACHEA, OR WINDPIPE 
137 
except by making characters with the fingers were called 
deaf and dumb. They are not dumb, but their deafness 
prevents them from learning to speak by hearing. They 
can learn to talk, however, by observing how another holds 
the lips, tongue, 
and teeth when 
speaking. 
The Trachea, or 
Windpipe. - This is 
a tube about an inch 
in diameter and 
four inches long, 
extending from the 
larynx to near the 
center of the chest, 
where it divides into 
two parts called 
bronchi. These 
branch to help form 
the lungs. Since 
the pressure of the 
muscles and the air 
have a tendency to 
push together the 
walls of the trachea, 
they are stiffened by 
more than a dozen 
rings of cartilage, incomplete at the back. Mucous mem- 
brane forms tiie inner layer of the trachea, and cells with 
cilia cover the surface and aid much in working all bac- 
teria and dust particles up to the mouth. 
Fig. 93.-Wax cast of the trachea of a cat, show- 
ing the branches of the trachea in the lungs. 
The trachea was poured full of melted wax, 
which became solid when cooled, and the lung 
tissue was then eaten away with acid, t, 
trachea; b, bronchus; h, bronchial tube; e, 
bronchioles. Blood vessels, black. (Prepara- 
tion by Sylvester, of Princeton University.) 138 
THE RESPIRATORY SYSTEM 
The Lungs. - Ihere are two lungs, the left one being 
slightly smaller than the right. Both have their bases 
resting on the diaphragm, while the apex, or top, of each 
lies just back of the collar bone. Between them is the 
heart. The lungs are covered by a transparent membrane, 
the pleura, which also lines the thoracic cavity. Pleurisy, 
which is the soreness or inflammation of the pleura, is 
caused by the growth of germs on 
the membrane. These are car' 
ried there by the blood or lymph. 
The lungs are spongy bodies 
consisting of the two bronchi 
with all their tubular branches, 
enveloped by numerous blood 
vessels, nerves, air sacs, and con- 
nective tissue. The branches of 
each bronchus are named bron- 
chial tubes. The smaller termi- 
nal branches beyond the bronchial tubes are the bron- 
chioles, each of which ends in a group of air spaces, 
called air sacs. The walls of these air sacs are pushed 
out in a dozen or more places, forming tiny pouches 
called air cells (Fig. 94). 
The Air Cells. - In the lungs are millions of air cells, 
all of which form part of the walls of the air sacs at the 
termination of the tubes conveying air. By air cells 
is meant air spaces and not cells such as are spoken of 
through the body. The walls of the air cells are as 
thin as tissue paper and are covered with a network of 
blood capillaries. The oxygen breathed into the air 
cell as part of the air is thus able to reach the blood, 
Fig. 94. -The termination of 
one of the thousands of 
bronchioles, br, like e in 
Figure 93. al, air sac with 
a dozen or more air cells. HOW BREATHING IS MAINTAINED 
139 
while the carbon dioxide passes from the blood to 
the air cell. 
The air in the air cells must be constantly changed to 
keep up the supply of oxygen and to get rid of the carbon 
dioxide. This is done by the action of many muscles, 
producing an inward and then an outward flow of aii 
through the trachea 
and tubes of the 
lungs. This pro- 
cess is called breath- 
ing and is necessary 
for respiration. 
How Breathing 
is Maintained. - 
Breathing consists 
of inspiration, or 
inhaling air into 
the lungs, and ex- 
piration, or exhal- 
ing air out of the 
lungs. The air or 
atmosphere presses 
upon every object it touches in the same way as water 
presses on anything immersed in it. Air flows toward 
the place where the pressure is least. The pressure of air 
in a vessel or cavity may be decreased by increasing the 
size of the vessel or cavity and not permitting any air to 
enter. 
When the lungs are removed from the body of a mouse 
and placed in a bottle, with a glass tube extending from 
the trachea out through a hole in a tight rubber cork, and 
Fig. 95. - The position of the diaphragm and 
ribs when the chest cavity is enlarged to admit 
air into the lungs is shown at the right. The 
figure on the left shows how the chest cavity is 
decreased to push out the air from the lungs. THE RESPIRATORY SYSTEM 
140 
the air then pumped out of the bottle, the lungs will ex- 
pand. The air runs down the tube and presses out every 
air sac, thus filling the space that the air had occupied. 
During life air goes into the lungs when the pressure on 
the outside of the lungs is decreased by enlarging the 
cavity of the chest (Fig. 95). This decrease of pressure 
is produced by the contraction of certain muscles, and 
when these muscles are relaxed, the pressure of the ribs 
on the lungs causes the breathing out of the air. 
How Breathing is Regulated. - Breathing occurs usually 
at the rate of about fifteen times per minute. During sleep 
it is slower; while violent exercise increases it to more 
than thirty times per minute. This is due to the fact that 
in sleep the tissues are more quiet, and therefore requin 
little oxygen, while during exercise the muscles are con- 
suming oxygen rapidly, and it can be supplied from the 
lungs only. When the tissues need oxygen, a message 
is sent to the cells of the spinal cord, which orders the 
muscles of the chest used in breathing to work faster. 
Respiration. - Passing air in and out of the lungs is 
wrongly called respiration. True respiration is of two 
kinds: the external or blood respiration occurs in the 
lungs, while internal or tissue respiration takes place in the 
tissues all over the body. Blood respiration consists in 
the passage of oxygen from the air cells into the blood 
and of the carbon dioxide from the blood into the air cell. 
The air received into the lungs contains in every 10,000 
parts 4 parts of carbon dioxide, 2096 parts of oxygen, 
and 7900 parts of nitrogen. When it issues from the 
lungs, there are 438 parts of carbon dioxide, 1602 parts of 
oxygen, and 7900 parts of nitrogen. THE CAPACITY OF THE LUNGS 
141 
Tissue respiration consists in the giving up of the 
oxygen of the blood to the cells of the tissues, and the 
receiving of the carbon 
dioxide from the tissues 
into the blood. No 
cell can do its work 
without a constant 
supply of oxygen, and 
in doing its work some 
of the oxygen must 
unite with the carbon 
to form carbon dioxide. 
The Capacity of the 
Lungs. - In ordinary 
breathing, only one pint 
of air passes in and out 
of the lungs. This is 
called the tidal air. In 
addition to this three 
pints of air may be 
breathed in by effort. This is complemental air. After 
the ordinary expiration about three pints of air, named 
the supplemental air, may by effort be forced out, but 
there will still remain some air in the lungs. This is 
residual air. The vital capacity of the lungs is the 
quantity of air that can be breathed out by the deepest 
expiration after the deepest inspiration. The usual 
amount is about four quarts for an adult. 
Measuring the Lung Capacity. - Some idea of the ca 
pacity of the lungs may be derived by measuring the cir- 
cumference of the chest after as much air as possible is 
Fig. 96. - Measuring the capacity of the 
lungs. The bottle was filled with water, 
which is being forced out by expiring 
the air from the lungs through the rubber 
tube slipped up into the mouth of the 
bottle kept under water in the pan. 142 
THE RESPIRATORY SYSTEM 
forced out, and then again measuring it after the fullest 
inspiration. The difference is usually from two to four 
inches. More accurate knowledge of the lung capacity 
may be gained by filling a gallon bottle with water, cork- 
ing it, turning it upside down in a pan of water, pulling 
out the cork, and then by means of a rubber or glass tube 
Fig. 97. - On the left is shown the normal position of the organs and on 
the right the effect of tight clothing worn around the waist. Z, liver; 
s, stomach; i, large intestine. 
slipped up in the neck of the bottle, blowing the fullest 
expiration of air into it. The air will force more or less 
of the water out. By measuring the water left in the 
bottle and subtracting the amount from one gallon, the 
vital capacity of the lungs may be known. 
How Clothing affects Breathing. - In order that all 
parts of the lungs may easily be filled with air, both the 
diaphragm and the ribs must be free to move. Tight 
clothing about the waist not only hinders free respira- 
tion, but stops in soipe degree the circulation of the 143 
SHORTNESS OF BREATH 
blood, and worst of all presses the internal organs of the 
abdomen out of place. In this way serious ill health is 
often caused in later life. The evil results of tight bands 
worn about the waist, especially by young girls, frequently 
Fig. 98.-Method of restoring breathing in a person partially drowned. 
This individual was unconscious about a quarter of an hour after being 
taken from the water. (From a photograph taken after recovery.) 
continues to make the life of the victim miserable to its 
end. 
Shortness of Breath. - The least exertion sometimes 
causes a person to breathe very rapidly. This may be 
due to heart disease or may result from tuberculosis 
having destroyed part of the lung tissue. Excitement 
frequently causes the nerves to send a message to the 
muscles forming part of the walls of bronchioles, and THE RESPIRATORY SYSTEM 
144 
makes them contract and shut off much of the air from 
the air cells. The catching for breath in case of asthma 
is due to the contraction of the muscles of the air 
tubes. 
Modified Breathing. - Sneezing is a forced expiration, in 
which most of the air is made to pass through the nose. 
Hiccoughing is a sudden inspiration, caused by the quick 
contraction of the diaphragm. Coughing is a forced ex- 
piration; in which the larynx is suddenly opened wide. 
Snoring is an inspiration with the tongue and soft palate 
held in such a position as to make the air pass partly 
through the mouth and partly through the nose so as 
to produce a fluttering of the soft palate. Whistling is 
either an expiration or an inspiration with the lips so 
puckered as to cause a vibration of the air within the 
mouth. 
Artificial Breathing. - The bite of a poisonous snake, 
electrical shocks, or partial drowning may cause the mus- 
cles controlling breathing to cease acting for a few min- 
utes. If some artificial means are used to make the air 
pass in and out of the lungs for a few minutes, the ner- 
vous system may recover from the shock, and normal 
breathing again take place. 
Of the several methods in use to produce artificial 
breathing that brought into use by Schaefer, in 1904, 
seems to be the most effective. The patient is immedi- 
ately turned face downward, and a heavy folded coat, 
plank, or bunch of weeds is laid under the chest and 
upper part of the abdomen (Fig. 98). The operator then, 
standing astride and facing the head of the subject, places 
his hands, one on either side, over the lowest part of the EXERCISING THE LUNGS 
145 
ribs. By slowly bending forward and thus pressing on the 
thorax, the air is driven out, and by gradually relaxing the 
pressure without moving the hands from their places, the 
air is drawn into the lungs. These movements should 
be performed about a 
dozen times per minute. 
A half hour is some- 
times required to estab- 
lish normal breathing. 
Exercising the Lungs. 
- The lungs, when 
filled to their fullest 
extent, contain nearly 
five quarts of air. In 
ordinary breathing 
only about a half quart 
of air passes out and 
in. It is evident, there- 
fore, that many of the 
air cells are not being 
used to their fullest extent, and under such conditions 
disease germs are more likely to set up growth. There 
is much evidence to show that consumption may be 
prevented, and in many cases even cured, by spending a 
few minutes several times daily in filling the lungs to 
their fullest capacity at every breath, and by living in 
the open air with an abundance of food. 
Breathing exercises also cause the lymph with its col- 
lected impurities to pass on into the blood stream for 
purification by the kidneys and lungs. These exercises, 
practiced daily for three months, will often enlarge the 
Fig. 99. - Air sacs at the end of air tubes in 
the lungs, a, from a lung not exercised; 
b, from a lung well exercised. The figures 
above are cross sections magnified. 
DAV. PHYS. - 10 146 
THE RESPIRATORY SYSTEM 
chest of a person under thirty years of age from one inch 
to three inches in circumference. If, when the lungs are 
full of air, the chest is beat lightly with the fists, the 
exercise is still more effective. Round and drooping 
shoulders and weak back 
muscles are corrected in 
a great measure by lung 
exercises together with 
the arm movements 
upward and downward, 
outward and inward, 
and forward and back- 
ward to their full ex- 
tent. 
Some Common Dis- 
eases of the Respiratory 
System. - Nearly all 
of the diseases of this 
system are due to germs. 
About one fourth of all deaths result from disease of the 
lungs. Tuberculosis kills over 4,000,000 in the world 
annually, and pneumonia destroys about as many in the 
United States as tuberculosis. The way for these two 
diseases is often prepared by catarrh, an inflammation of the 
mucous membrane. A temporary inflammation of the lin- 
ing of the air passages, caused by germs overcoming the body 
cells when weakened by exposure, is called a cold. Mem- 
branous croup and diphtheria are diseases of the throat, pro- 
duced by a special kind of bacteria often transferred from 
mouth to mouth by the drinking cup. Since the sputum 
coughed up from the throat and lungs may contain some 
Fig. 100. - Expression often present in 
children with adenoid growths in the 
back part of the nose. TOBACCO AND THE RESPIRATORY SYSTEM 
147 
of these harmful germs, they should never be deposited on 
the sidewalk or on the floor of a car or a house. When 
dried, they will be blown 
about in the air, breathed, 
and thus make others sick. 
Adenoids. - Adenoids 
are spongy growths fre- 
quently occurring in the 
back part of the nasal 
cavities of children. They 
interfere with the blood 
supply to the brain, clog up 
the nasal passages, cause 
mouth-breathing and indis- 
tinct pronunciation of 
words. Listlessness, inat- 
tention, poor memory, par- 
tial deafness, and frequent 
colds, or earache may re- 
sult from adenoids. These 
structures are very common 
in children of school age. 
Signs indicating their presence are parted lips, prominent 
eyeballs, a narrow and high-arched roof of the mouth, and 
nasal speech. They are easily removed by a physician. 
Tobacco and the Respiratory System. - While tobacco 
affects more seriously the heart and nervous system, yet it 
also leaves its evil impress on the respiratory organs. 
The heat and gases, produced in smoking tobacco, tend 
to dry the mucous membrane and act as irritants to the 
throat, nasal passages, and larynx. After some years 
Fig. 101. -Section of the head show- 
ing adenoid growths a and 6; i, 
uvula; u, tonsil; t, tongue. Arrows 
show the direction of the air. 148 
THE RESPIRATORY SYSTEM 
those addicted to the chewing of tobacco or the smoking 
of the cigarette nearly always have a husky voice, due to 
the effects of tobacco on the vocal cords. 
In cigarette smokers it is through the lungs that the 
poison chiefly reaches the blood. Those using pipes and 
cigars seldom inhale the smoke into the lungs, while over 
nine tenths of the cigarette users do. This permits the 
carbon monoxide, a poisonous gas generated from the burn- 
ing of the tobacco, and the nicotine to pass readily into 
the blood and poison the nerves. 
An examination for nine years of the boys in one of the 
large eastern colleges showed that the non-users of tobacco 
gained during four years in chest development 26.7 per 
cent more than the habitual users of tobacco. The con- 
tinual use of tobacco decreases very markedly the lung 
capacity, as has been shown by many careful measure- 
ments taken at a New England college. 
Alcohol and the Organs of Respiration. - One of the 
most constant effects of alcohol, especially if used in con- 
siderable amounts, is to lessen the rate and depth of 
breathing. In this way many of the air cells of the lungs 
fail to be expanded, and disease is invited. Of all the 
cases of tuberculosis in the New York Hospital on Black- 
well's Island, one half are declared to be due to the use of 
alcohol. Dr. Crandall, in his book " How to Keep Well," 
states that users of alcohol are particularly liable to pneu- 
monia. The United States Census Reports show that 
with the increased use of alcoholic drinks in this country 
there has been a marked increase in the number of deaths 
resulting from pneumonia. Physicians declare that the 
use of alcoholic drinks causes the death of a large proper^ SUGGESTIONS FOR THE TEACHER 
149 
tion of the three hundred thousand who die in this country 
yearly from disease of the respiratory organs. 
Questions 
1. Of what use is oxygen in the body ? 2. IIow is oxygen supplied 
to the tissue? 3. Name the parts of the respiratory system. 4. Of 
what special use are the nasal passages ? 5. Describe the pharynx. 
6. What are the chief features of the larynx ? 7. Describe the vocal 
cords. 8. IIow is voice produced ? 9. On what do the loudness and 
the quality of the voice depend ? 10. Describe the trachea. 11. Ex- 
plain how the air tubes end. 12. Of what use are the air cells? 
13. What causes the air to rush in and out of the lungs ? 14. Why 
do you breathe quicker after running ? 15. Explain what is meant 
by two kinds of respiration. 16. State some facts concerning the 
capacity of the lungs. 17. IIow does clothing affect breathing? 
18. What causes shortness of breath? 19. Describe how artificial 
breathing may be produced. 20. Why is it important to exercise the 
lungs? 21. State five facts concerning disease of the respiratory 
system. 22. In what way does tobacco harm the respiratory system ? 
23. Give some evidence showing that cigarettes are harmful. 24. How 
does alcohol affect the respiratory system? 25. What is the evi- 
dence that alcohol does not prevent disease ? 
Suggestions for the Teacher 
1. Procure from the butcher the lungs of a small pig or lamb. 
Pick loose with a pin some of the transparent glistening pleura cover- 
ing the surface of the lungs. Slit open the trachea and bronchi, not- 
ing the mucous membrane lining them, and observe the numerous 
branches of each bronchus as it pierces deeper into the lung. 
2. The larynx of a calf or other animal secured from the butcher 
will, when cut open from before backward, show clearly the vocal cords 
very similar to those in man. 
3. By means of a gallon bottle and tube, as shown on page 141, ask 
several pupils to measure the capacity of their lungs and also the 
amount of air ordinarily expelled at a breath. This will tell them 
how much of the lungs is unused, and therefore in a condition to be- 
come diseased. See that the end of the tube put into the mouth is 150 
THE RESPIRATORY SYSTEM 
well cleaned after each pupil uses it. A glass tube is preferable to 
rubber. 
4. Have the pupils perforin the following lung exercises : Standing 
erect, with shoulders thrown back, breathe in through the nose until 
the lungs are entirely filled; then exhale. Do this at the rate of a 
dozen times per minute for five minutes. For a few minutes, at the 
rate of thirty times per minute, swing the arms up and down from the 
sides of the body to above the head. Then, at the rate of forty times 
per minute, extend the arms forward in front of the body and draw 
them back until the closed fists strike the chest. During the next 
three minutes swing the extended arms forward so that the palms 
strike together in front of the body and then backward until they 
strike together behind the back. Explain that these exercises, prac- 
ticed daily in the fresh air, are of great importance in warding off 
consumption and other diseases. XIV. AIR AND HEALTH 
Composition of Air. - Air is composed chiefly of the 
two gases oxygen and nitrogen, which are merely mixed 
and not combined chemically like carbon and oxygen 
in carbon dioxide. Because of this fact the blood is 
able to take up the oxygen only, without in any way 
affecting the nitrogen. The fact that there are four parts 
of nitrogen in the 
air to one part 
of oxygen may be 
shown by causing 
the oxygen in a jar 
to unite with the 
head of a match. 
About a fourth of 
a match bearing the 
head should be laid 
on a chip of wood or cork floating in a pan of water. 
After lighting the wood of the match with a taper, a 
glass is to be set over it just as the flame reaches the 
match head. The oxygen in the jar will be used up 
by the burning sulphur and phosphorus, and no more can 
get in on account of the water at the mouth of the jar. 
The white fumes formed from the burned-up oxygen will 
be absorbed by the water, which will then rise and occupy 
the same space before filled by the oxygen. By slipping 
Fig. 102. - Experiment showing the amount of 
oxygen in the air. In the figure at the left c 
is a cork bearing a piece of match, which, by 
burning, used up the oxygen so that the water 
rose in its place, as shown in the figure at the 
right. 
151 152 
AIR AND HEALTH 
a piece of paper under the water and over the mouth of 
the glass, it may be turned up without allowing oxygen to 
enter. If the paper cover be then moved to one side a 
little and a burning stick thrust in, the flame will at once 
go out, because there is no oxygen present. There are 
about 4 parts of carbon dioxide in every 10,000 parts of 
air. 
The Extent of the Air. - The air, or atmosphere, ex- 
tends to a distance of ninety miles from the earth, and is 
present in the soil and the tissues of all plants and ani« 
mals. Its presence in water makes it possible for fish to 
get oxygen by means of the gills, between which the water 
is continually passing from the mouth outward through 
the opening at the side of the head. At high elevations, 
as on mountain tops, the air is much less dense, and it is on 
account of the thinness of the air that ascent in a balloon 
above five miles proves fatal to the occupants. 
The Source of the Air. - Billions of creatures are con- 
stantly using the oxygen to maintain life, and a new sup- 
ply is continually being formed through the agency of 
plant life. All grass and trees or other plants of a green 
color give off large quantities of oxygen under the influ- 
ence of sunlight. At the same time they use up much 
carbon dioxide breathed out by the animals. Plants use 
oxygen also in respiration, but they get during daylight 
much more oxygen than they can use from the carbon 
dioxide, and therefore set it free. Carbon dioxide and 
nitrogen are the two most important of all plant foods. 
If a small candle is lit and put in a glass box having 
a space of twelve cubic feet, it will be extinguished 
in about one hour by the carbon dioxide given off. If IMPURITIES IN THE AIR 
153 
the same experiment is made again and the box is filled 
with large leafy plants, and exposed to the bright sun, the 
candle will continue to burn, because the carbon dioxide 
is consumed by the plants. 
Gases pass to and from the plants through breathing 
pores, which appear in young apple and pear branches 
as minute white elevations smaller than the head of a pin. 
Breathing pores are more numerous on the leaves, but 
much smaller, so they can be seen only with the aid of 
the microscope (Fig. 103). 
An acre of grass will give off enough oxygen on a 
Fig. 103. - Surface of a leaf, showing eight breathing pores. Photo- 
graphed through the microscope. 
bright day to supply the wants of ten people at ordinary 
labor. The fact that plants do yield oxygen may be 
shown by placing a funnel over some water plants in the 
water exposed to bright sun, and running the tube of the 
funnel into a small vial filled with water. The oxygen 
may be seen rising in bubbles, and in the course of an hour 
enough of it will have collected in the bottle to be tested 
by a live coal on a burnt stick. If oxygen is present, the 
stick will burst into a flame when thrust into the bottle. 
Impurities in the Air.-The commonest impurities in 
the air out of doors are dust and germs, some of which 154 
AIR AND HEALTH 
produce disease. Only air far out over the ocean or on 
the top of high mountains is quite pure. During the 
first hour after a prolonged rain almost no impurities are 
present in the air of country places. The number of 
germs in city air during business hours and on dry days 
varies usually from 1000 to 10,000 in every cubic yard. 
By keeping the streets well sprinkled these numbers may 
be lessened more than four fifths. Dust and particles 
of soot, together with many germs, tend to make city life 
much less healthy than life in the country. 
Foul Air. - This is air so full of gases from decaying 
matter or other sources that it has a bad odor and cannot 
be breathed long without affecting the health. The air 
of a room containing many people for an hour without 
ventilation becomes foul. In mines or deep wells carbon 
dioxide sometimes collects and causes quick death by 
suffocation to any one descending into them. It does 
this by preventing the red cells of the blood from get- 
ting enough oxygen to carry to the tissue. Foul air, 
such as that from sewers or cesspools, generally contains 
no germs, and therefore cannot convey to a person such 
diseases as diphtheria and typhoid fever, as some people 
suppose. 
Night Air. - Until late years night air was considered 
unhealthy, because those who were out after night, espe- 
cially in wet regions, were often attacked a few days later 
with malaria. It is now known that the malaria was not 
due to night air, but to minute animal germs trans- 
ferred from one person to another by the bite of a certain 
kind of mosquito, in which the malaria germs live and 
multiply after the insect has sucked blood from a malaria MOUNTAIN AIR 
155 
patient. One may sleep in the swamps and morasses 
in any part of the world without taking malaria if the 
mosquitoes are kept away by netting. 
No one can get too much night air if he keeps warm. 
Night air has by analysis been shown to be much purer 
than day air, because the dust and germs settle to the 
earth when no one is 
about to stir them up. 
At night the windows 
of the bedroom should 
be kept open if one 
wishes to avoid colds, 
pneumonia, and espe- 
cially consumption. 
During cool weather it 
is important that the 
head should be- pro- 
tected by a nightcap 
if there is any tendency 
to catarrh or sore throat. 
Sleeping in the night air has been one of the most 
efficient means used in curing thousands of cases of 
tuberculosis. 
Mountain Air. - Some people feel better when living 
in a mountainous region, and frequently those affected 
with lung disease are sent to the mountains to recuperate. 
The beneficial effect of mountain air may be due in part 
to the fact that it contains less germs and dust and is 
drier, but the chief benefit comes from the fact that the 
air is not so dense and the patient must exercise his lungs 
more to get the necessary amount of oxygen to feed the 
Fig. 104. - Two malaria germs each in a 
blood corpuscle. Photographed through 
the microscope. 156 
AIR AND HEALTH 
tissues. It has been found that lung disease can be cured 
almost as well in any pure air if the patient will follow 
the physician's rules in reference to hygiene. 
Seashore Air. - There is undoubtedly some element in 
the air along the sea not to be found inland. Certain 
forms of tuberculosis, especially that affecting the bones, 
get well in seashore air sooner than elsewhere. The sea- 
shore is also beneficial to sufferers from hay fever. 
Respired Air. - This is air which has been acted on by 
the blood in the capillaries of the lungs and then expelled. 
It consists of about 80 parts nitrogen, 16 parts oxygen, 
and 4 parts carbon dioxide. This shows that the blood 
has taken up 4 parts of oxygen and given out in return 4 
parts of carbon dioxide, while the nitrogen is in no way 
affected. Although germs are always present in the in- 
spired air, no germs are given out in the expired air, even 
if the person is suffering from some disease. The germs 
are held fast on the moist mucous membrane. A sudden 
expiration, such as a cough or a sneeze, will, however, throw 
out many germs. As the expired air contains much more 
moisture and heat than that inspired, this is one way in 
which the body loses heat and water. A minute amount 
of organic matter is also present in respired air, and it is 
partly this which makes the air of unventilated rooms so 
unhealthy. 
Need of Ventilation.-No one is expected to eat the 
rood which has been once in his stomach or that of an- 
other and then cast out. Neither should one be expected 
to take into his lungs the air which has just come from 
them or from the lungs of some one else. This uncleanly 
habit, however, is common in most churches, schools, and HOW TO VENTILATE 
157 
other public indoor gatherings. Ventilation, which means 
allowing the free entrance of pure air and the passing 
out of the impure air, is poorly provided for in most school- 
houses. As a result the children become listless and in- 
attentive, and the teacher frets and scolds because of a 
weariness of the flesh produced not by work but by bad 
air. Boys and girls at school do not break down from 
overstudy, but from lack of exercise and fresh air. Liv* 
ing in closed rooms by 
day and sleeping with- 
out windows raised at 
night is a gentle way of 
committing suicide. 
How to Ventilate. - 
Since the flow of cold 
air upon the body may 
make one ill, the fresh 
air must have inlets 
where it will not strike 
directly on any one in the room. Two or three windows 
all on one side of the room, pulled down several inches 
from the top and raised a few inches at the bottom, afford 
excellent ventilation. If a board, slanting inward, is 
placed in the bottom of the window so as to direct 
the current of air upward, no draft will usually be 
felt, even by those within a few feet of the window. 
The height of the board should be twice as great as 
the opening in the window, and triangular pieces at the 
ends will shut out the current tending to enter there. 
To show clearly how to ventilate, a box with a small 
lighted candle, as in Figure 105, may be used. The candle 
Fig. 105. - Experiment in ventilation. A 
pane of glass forms the front side of the 
box. 158 
AIR AND HEALTH 
uses up oxygen, makes heat, and gives off carbon dioxide 
in the same way that people do. Four half-inch holes, 
bored in each end of a box with a capacity of 400 cubic 
inches, are fitted with corks 
and a pane of glass serves 
for one side. By removing 
the corks from one group 
of holes at a time, it is 
easy to determine which 
supplies the larger amount 
of air, as the candle flame 
goes up and down accord- 
ing to the amount of oxy- 
gen and carbon dioxide 
present. With all the 
corks in, the candle is ex- 
tinguished in one minute. 
If two corks on the same 
end at the top are removed, 
the candle will burn two 
minutes. The removal of 
the two corks at the top in 
both ends allows the candle 
to burn three minutes, 
while if the corks are all 
in except two in the same 
end, one being out at the 
top and the other at the 
bottom, the candle will continue to burn until con- 
sumed. This is clear proof that only two openings, 
one low and one high, on the same side of a room afford 
Fig. 106.-Diagram showing how to 
open the windows so that all pupils 
may have fresh air. The course of 
the air currents were determined by 
smoke and the brightness of the 
candles burning in different parts of 
the box. i, inlet for air; o, outlet 
for foul air. The dotted line is the 
level of the heads of the pupils. HOW TO VENTILATE 
159 
better ventilation than twice as many opening at the 
top. 
When a basement heater is used, plenty of fresh air 
may be furnished by leading it through a duct from the 
outside to the furnace to be heated and sent to the rooms 
above. On this 
account hot air is 
much more healthy 
than steam for heat- 
ing purposes unless 
a special arrange- 
ment is made for 
supplying fresh air 
or drawing the im- 
pure air out by 
means of a fan. 
When air is forced 
into a room, it 
should enter near 
the ceiling, and an 
opening for the 
escape of the impure air should be on the same side 
of the room near the floor. 
The thousands of schoolrooms in rtiral districts where 
the stove is used may be well ventilated by adopting the 
plans shown in the figure. The stove is surrounded by a 
sheet-iron jacket standing off about six inches. The pure 
cold air enters through the duct beneath the stove, which 
warms it as it flows upward and then over the room, as 
shown by the arrows. Behind the stove is an opening 
into a brick flue for the escape of the impure air. This 
Fig. 107. - Section of a schoolroom heated by a 
stove. Arrows show the course of air currents. 
a, fresh air duct; b, stove; c, sheet iron jacket; 
d, outlet for impure air; e, smokepipe; f, flue 
for impure air. AIR AND HEALTH 
160 
nue extends above the root and contains the sheet-iron 
smoke pipe, which warms the air and thus makes an up- 
ward draft. Good ventilation, with a pan of water on the 
stove to keep the air moist, will prevent much of the 
catarrh and colds from which children suffer. 
One certain means of 
getting a supply of fresh 
air in a schoolroom is to 
have a few minutes' recess 
at the end of each hour and 
open wide the doors and 
windows. Prevention of 
ill health is better than cur- 
ing it. Late investigations 
prove that fresh air is one 
of the three greatest pre- 
ventives of disease. 
Amount of Air Breathed. 
- At each breath an adult 
uses about 30 cubic inches 
of air, and as breathing 
occurs nearly 20 times per 
minute, 600 cubic inches of 
air are inhaled, making a 
jotal of 36,000 cubic inches 
per hour. The air of the schoolroom should never con- 
tain more than 7 parts of carbon dioxide in 10,000. To 
prevent the air from becoming impure, 2000 cubic feet of 
fresh air should be supplied every hour for each pupil. 
Temperature and Moisture. - One cannot think well or 
work to his greatest capacitv in a room that is too warm. 
Fig. 108. - A window board that admits 
fresh air. VENTILATION 
161 
If the room is too cold, illness may result. The most 
favorable temperature for a schoolroom is sixty-eight de- 
grees. Overheated rooms cause many children to take 
cold in winter. Frequently the air of a room, on account 
of the heat, is so much drier than the atmosphere that it 
gives rise to a catarrh or inflammation of the mucous 
membrane of the nose and throat. The air may be kept 
moist by a pan of water set on the stove or radiator. 
Recent experiments have shown that the ill effects 
occasioned by a poorly ventilated room are due at least 
as much to uncomfortable skin sensations as to the 
excess of carbon dioxide in the air. Two adjoining 
rooms were used. Pipes led through the walls of one 
room into the other. The first room with tightly closed 
windows was filled to capacity with students who were 
given a stated amount of work to do. Five of these 
students were placed next to the wall with coverings 
over their noses and mouths connected with the pipes 
leading into the adjacent room. This room was perfectly 
ventilated. Thus these five students were breathing 
pure air although they were seated in the close room. 
Soon it was found that all the students showe I disin- 
clination for work, drowsiness, and flushed cheeks. Those 
seated at the pipes showed no advantage over the others. 
In the next room were five other students seated near the 
wall and breathing the used air of the first room. These 
showed no signs of discomfort or of diminished working 
power. When electrical fans and other means were 
taken to regulate the humidity, the students regained 
much of their lost energy. 
Use has been made of this knowledge in installing 
DAV. PHYS. 11 162 
Alli AND HEALTH 
various types ot ventilators in new office buildings the 
chief purpose of which is to keep a good circulation of 
air in the rooms. 
Sweeping and Dusting. - 
Rugs are preferable to nailed- 
down carpets, for they may 
be put out of doors in the 
sun for cleaning. The dust 
may be then beaten out of 
them without settling in the 
room. Floors and furniture 
should be wiped with a damp 
cloth to which the dust and 
germs will adhere and not 
fly into the mouth of the 
cleaner. There is evidence 
to show that disease germs 
are present on the floors of all public buildings and of 
most houses in towns and cities. Care in cleaning means 
escape from sickness. 
A short time ago the Upsala Street School of Worcester, 
Massachusetts, decided to throw away the old feather 
dusters and use moist cloths for dusting. As a result there 
was not a case of contagious disease in a school of 425 
pupils during the entire school year. This condition of 
health had never prevailed before in the history of the 
school. 
Disease and Air. - Dust-laden air and air in poorly 
ventilated rooms is known to be responsible for much of 
the illness affecting the respiratory system. Tool grinders, 
cement workers, and factory hands, breathing air laden 
Fig. 109. - A revolving fan will re- 
move the bad air. DISEASE AND AIR 
163 
with minute particles of matter cast off from the ma- 
terials upon which they are working, are specially liable 
to lung diseases. All patients at sanatoria for consump- 
tion are compelled to remain practically out of doors night 
and day. Even with the thermometer twenty degrees 
below zero, one entire side of the room in which the 
patient sleeps is left open. More than half of those tak- 
ing this fresh air, rest, and food treatment at the sanatoria 
in this country recover from their sickness. If fresh air 
will cure disease, it surely will prevent disease. 
Questions 
1. What is the composition of air? 2. How can you separate the 
nitrogen from the oxygen of the air ? 3. What is the source of the 
oxygen of the air ? 4. How can you show that plants give off oxygen ? 
5. Name some of the impurities in air. 6. Describe foul air and its 
effect on health. 7. Why should persons sleep with their windows 
open ? 8. Explain fully how to ventilate a room in summer. 9. Ex- 
plain how to ventilate a schoolroom heated with a stove. 10. How 
much pure air is required for each person per hour? 11. How do 
temperature and moisture affect health? 12. How may the air of 
a room be kept moist ? 13. Why should nailed-down carpets not be 
used ? 14. What is the effect of breathing much dust ? 
Suggestions for the Teacher 
1. Prepare a cup of limewater by pouring slowly a half glass of 
warm water on a heaping tablespoonful of fresh lime. Five minutes 
later add to this a glass of water, stir well and pour it into a bottle 
which should be well corked. The clear liquid appearing in a day or 
two on top of the sediment is limewater. Put some of this into a cup, 
and with a glass tube let a child breathe a few times into the liquid. 
The white material resulting is calcium carbonate, formed by the union 
of the carbon dioxide of the breath with the lime. Place a dish of 
limewater and a lighted candle in a box for a few minutes, and note 
the result. Let some dishes of limewater stand an hour or two in 164 
AIK AND HEALTH 
rooms that are well ventilated and some dishes in other rooms not 
well ventilated, and note the result. 
2. Ask some of the pupils to make a box for ventilating experi- 
ments, as shown on page 157. Show how poorly the candles burn 
when there is poor ventilation, and explain that the human body is 
weakened in the same way by an insufficient supply of pure air. 
3. Demonstrate upon a pupil the method of producing artificial 
breathing and then require some of the pupils to continue the 
demonstration. XV. ALCOHOLIC DRINKS AND THEIR 
EFFECT ON THE HUMAN RACE 
The Nature of Alcohol. - There are many different 
kinds of alcohols, but all are compounds of carbon, oxygen, 
and hydrogen, the elements we have found present in 
nearly all our daily foods. Alcohols are as a matter of 
fact largely derived from carbohydrates which undergo 
a process known as fermentation. Alcohol burns readily 
and is fuel outside of the body. Inside the body it is 
also readily oxidized, and for this reason some people 
have regarded it as a food. However, as the effect of 
the alcohol is to cause an excessive amount of blood to 
flow to the skin where its heat is quickly lost to the 
surrounding air, the result is a decrease rather than an 
increase in body energy. Since, therefore, it cannot be 
used to rebuild tissue, and since it causes a loss of heat, 
its effect on the body in the long run is injurious, and it 
ought not to be classed as a food. 
Wood alcohol is derived from materials containing a 
quantity of woody fiber. It has value as a fuel and as a 
solvent of the materials which are used in making shellacs 
and varnishes, but it is so poisonous that its use is de- 
creasing in the industries. The effect of the fumes of 
wood alcohol is to produce blindness by attacking the 
nerves of the eye. Even a very small quantity taken 
internally may produce death. 
165 ALCOHOLIC DRINKS 
166 
Effect of Alcoholic Drink. - So intemperate and beast- 
like does alcohol sometimes render people that they fre- 
quently have no control over their appetites after taking 
a few drinks. 
Millions of dollars' worth of patent medicines contain- 
ing alcohol are sold yearly. Dr. A. P. Grinnell, who has 
made a study of this subject, declared, before the pro- 
hibition law was passed, that more alcohol was consumed 
in patent medicines 
than was dispensed by 
the licensed saloon. 
Use of Alcoholic Drink 
Decreasing. - Owing to 
the education of the 
public concerning the 
evils of the drink habit, 
the consumption of 
strong alcoholic liquors 
has decreased greatly. 
In 1840, when nearly every family used some whisky, the 
average amount consumed for each inhabitant was two 
and a half gallons, while in 1896 the amount was only 
one gallon for each individual. 
In 1920 the Eighteenth Amendment to the Constitution 
of the United States became effective. This prohibits 
the manufacture, sale, and transportation of intoxicating 
liquors anywhere in United States territory. The law 
defines "intoxicating liquor" as liquor which contains 
one half of one per cent, or more, of alcohol. Several 
other countries have also passed laws regulating the sale 
of liquor within their boundaries. 
Fig. 110. - The sizes of the rectangles show 
how the use of alcohol has decreased 
each decade in seven of the large London 
hospitals while the number of patients 
has greatly increased. ALCOHOL IN HEALTH 
167 
Alcohol in Health. - While it is possible for some older 
persons to drink small amounts of liquor daily for many 
years without apparent injury to themselves, yet experi- 
ence shows that of those beginning the use of beer, wine, 
or whisky before the age of twenty-five a large percentage 
are injured in health by the alcohol. A few years ago a 
report of the Committee of Fifty, known far and wide for 
its thoroughness and accuracy, furnished evidence that 
about 1,000,000 men were every year drinking to such 
an excess as to cause evident injury to health. 
The excuse often given for the use of these beverages 
is that they help one to perform more work. The Com- 
mittee of Fifty declared that the use of alcoholic drinks 
just before or during physical or mental work usually 
diminishes the total amount of work done. Dr. Wood- 
head, a professor in Cambridge University, writes as fol- 
lows: "No amount of alcohol, however given, can increase 
the amount of work done in that same period without 
giving rise to very serious disturbances in some part or 
other of the body." Dr. T. G. Roberts says: "It was 
formerly thought that alcohol augmented strength, but it 
has been found by experiment that the man who drinks 
it cannot lift so heavy a weight as those who do not." 
A good proof of the loss of working power was an experi- 
ment performed on workmen in a printing establishment. 
These laborers were paid for the amount of work accom- 
plished each day instead of for the number of hours spent. 
The work consisted of composing words from separate 
pieces of type. On alternate days they were given a 
small amount of alcohol. The workmen themselves be- 
lieved that they worked better on the days on which 168 
ALCOHOLIC DRINKS 
they had their liquor than on the days on which they 
abstained. It was found however that the actual work 
accomplished was 10% less on the days on which they 
drank the liquor and that there- 
fore their wages were decreased 
to the same degree. 
In England during the last 
war when shipbuilders were 
exerting themselves to the ut- 
most to build large numbers of 
ships in a short time, their 
worst enemy was found to be 
alcohol. The laborers, although 
they realized the importance of 
their work, lost, in the average, 
two days' work a week on 
account of drink. 
The habitual use of liquor 
has a tendency to weaken 
stomach digestion and decrease 
the value of food consumed. 
Dr. Brubaker, of the Jefferson 
Medical College, in Philadel- 
phia, says: "Alcohol deranges 
the activities of the digestive 
organs, lowers the body tem- 
perature, impairs muscle power, 
diminishes the capacity for sustained mental work, and 
leads to the development of structural changes in the 
connective tissues of the brain, spinal cord, and other 
organs." Beer is often advertised as a nutritious drink, 
Fig. 111. - Diagram showing 
how a small amount of alcohol 
taken on alternate days af- 
fected a type setter. The fig- 
ures at the left show the num- 
ber of letters set up. 169 
ALCOHOL AND DISEASE 
but analysis shows that it contains almost no nourish- 
ment. All scientists agree that in health beer, whisky, 
or wine should not be used for food. 
Alcohol and Disease.- Very few, if any, persons can 
drink liquor daily without causing disease or a tendency 
to disease in some of the tissues. The Committee of 
Fifty, as a result of years of investigation, say that " the 
excessive and continued use of alcohol affects the liver, 
kidneys, heart, blood vessels, and nervous system." A 
considerable amount of the dyspepsia afflicting moderate 
drinkers is due to the alcohol consumed. Most of the 
cases of shrinking and hardening of the liver result from 
alcohol. Excessive indulgence in alcoholic liquors is an 
important cause of Bright's disease, and in those who 
drink large quantities of beer diseased hearts are com- 
paratively frequent. There are many cases in which 
alcoholic poisoning is evidently the cause of serious disease 
of the brain, spinal cord, and nerves. One result of beer 
drinking is the unhealthy production of fat which may 
occur among the muscle fibers of the heart. The use of 
wine and strong beer or porter may produce gout. The 
records of one of the large insurance companies show that 
those not using alcohol suffer a ti'ifle over one half as 
many weeks' sickness annually as those who are not 
abstainers. 
Physicians state that pneumonia and tuberculosis are 
much more likely to produce death in habitual drinkers 
than in others. The Committee of Fifty finally says: "-The 
general conclusion is that fine old whiskies and brandies 
are nearly as likely to produce ill effects as the cheaper 
varieties," 170 
ALCOHOLIC DRINKS 
Professor Welch, of the Johns Hopkins University, says: 
" Catarrh of the larynx, pharynx, and bronchi is common 
in alcoholic patients." The famous Dr. Weichselbaum, of 
Vienna, in speaking of the effects of alcohol on the body, 
says: " The blood gradually becomes sluggish in the 
different organs ; namely, in the respiratory, digestive, 
and nervous systems. Such persons have an irregular 
weak heart, a chronic laryngeal and bronchial catarrh 
develops, and digestion becomes constantly poorer and 
slower; there are also brain and nerve derangements, due 
not only to the stagnation of the blood, but also to the 
direct action of alcohol on the nerve cells." 
Experience clearly proves that the persons soonest 
overcome with cold in winter or heat in summer are the 
users of alcohol. This is true because of the weakening 
or poisonous effect liquor has on the cells of the body. 
Alcohol and Poverty. - While the use of alcohol does 
not always make one poor, records show that thousands of 
families in need of help owe their condition to liquor. 
A constant drinker, in addition to consuming several 
hundred dollars' worth of beer, wine, or whisky yearly, 
renders himself unfit to earn much money. 
The Committee of Fifty, which spent much time and 
money to learn how much poverty alcohol caused, ascer- 
tained these facts: About one fourth of all cases of 
poverty brought to the notice of the Charity Organiza- 
tions are caused by alcohol, and more than one third of 
the inmates of almshouses are brought there through the 
use of liquor. The presence there of two fifths of the 
males is due to alcohol. Of 5136 cases of destitute chil- 
dren over 2300 were found to owe their sad state to the ALCOHOL AND CRIME 
171 
use of alcohol by the parents. The annual report of the 
Bureau of Labor of Massachusetts shows that two fifths 
of all the paupers in the almshouses in that state were 
brought to that condition by strong drink. 
Effects of Alcohol on the Offspring. - Experiments per- 
formed on alcoholized animals - dogs and rats - show 
that not only is the birth rate twenty per cent lower than 
that of the normal animals, but that many of the young 
are born dead or deformed. Statistics show that the 
children of alcoholic parents are born with badly devel- 
oped brains and nervous systems. They are stunted in 
growth, deficient in weight, suffer from anemia, and are 
far more susceptible to the children's diseases than the 
children of normal parents. 
Alcohol and Crime. - The wide and accurate scientific 
investigations lately completed by the Committee of Fifty 
prove beyond a doubt that alcohol not only wrecks the 
mind and body of thousands yearly, but also destroys 
character. The facts which they collected relate to 
13,402 convicts in state prisons and state reformatories 
in various portions of the United States. The first cause 
of crime in over 4000 of these was alcohol. Intemperance 
in over 6000 cases was one of the important causes of crime. 
Police records show that in one year there were arrested 
for drunkenness in Boston 24,000 persons, in Chicago, 
31,164, in Philadelphia 24,661, and in New York 31,534. 
National Loss through Liquor. -It is of course impos- 
sible to estimate the real value of homes, bodies, and char- 
acters ruined by strong drink. It is certain that over 
10,000 convicts in our prisons have been brought there 
through intemperance, and over thirty per cent of the ALCOHOLIC DRINKS 
172 
inmates of the almshouses owe their unhappy state to 
alcohol. The disease, suffering, and death due to liquor 
cannot be accurately computed, but the amount of money 
spent by the government and charitable organizations in 
caring for those poverty-stricken through drink is not less 
than $100,000,000. The time lost by the intemperate, if 
used in honest labor, would be worth at least $100,000,000. 
Alcohol as a Medicine. - Many years ago nearly every 
family kept a jug of whisky in the house to be used in 
case of sickness. To-day very few educated people keep 
spirits in the home, because the latest scientific investiga- 
tions show that neither whisky nor beer is of much if any 
value in curing disease. In most cases they make a 
disease worse. People should never use patent medicines, 
as many in the liquid form contain from ten per cent to 
thirty per cent of alcohol or other injurious drugs. It is 
due to the stimulating effects of the alcohol that most of 
these medicines make the consumer feel better for a time. 
Many people have contracted the terrible alcohol thirst 
by taking patent medicines. Dr. Knopf, an expert of 
international reputation, says: "Alcohol has never cured 
and never will cure tuberculosis. It will either prevent 
or retard recovery." 
Why Alcohol is called a Poison. - A poison is any sub- 
stance which, when taken into the body in sufficient 
quantity, will produce sickness or death. A single spoon- 
ful of wine or a small glass of beer would not perhaps 
make any adult sick, and therefore would not be a poison. 
If this small amount were taken daily for some weeks, it 
would in some cases so change the tissues that there 
would be a continual longing for strong drink, and the DANGER FROM THE USE OF ALCOHOL 
173 
craving might be so strong as to overpower the will. 
Under these circumstances the alcohol acted as a poison 
because it made some cells in the body sick. A small 
amount of strychnine or arsenic will not make one sick, 
yet we call them poisons. Whether alcohol is a poison 
or a food is of little consequence in judging its effects on 
humanity. The results of its use in any community are 
to increase crime, poverty, and death, and on this account 
the great statesman Gladstone said : " It is productive of 
greater evils than the combined scourges of war, famine, 
and pestilence." 
Danger from the Use of Alcohol. - Some persons can 
drink beer or wine occasionally without perceptibly injur- 
ing their health, yet their example may cause many to 
indulge who will be led on little by little until they be- 
come drunkards. Many who do not continue until 
drunkenness results, weaken their bodies and minds, and 
make themselves more liable to disease and crime. Re- 
ports secured from various parts of the United States 
show that at least one in every ten occasional drinkers 
becomes positively intemperate. Many people, after be- 
coming accustomed to the use of alcohol, are unable to 
stop drinking without being placed in confinement and 
kept there until the tissues have again become well. The 
tissues of the young are affected much more quickly, and 
an incontrollable appetite developed much sooner than in 
persons past fifty. 
The younger the individual the greater is the danger 
in taking an occasional drink. Helenius, in a paper read 
at the University of Copenhagen in 1902, showed that 
alcohol had fatally poisoned in the nineteenth century 174 
ALCOHOLIC DRINKS 
7,500,000 persons in the civilized countries of Europe, 
America, and Australia. All of these were at one time 
occasional drinkers. 
The one safe plan, then, is never to take the first drink. 
A young man can display no greater patriotism than 
to fight against that which brings to his country woe, 
want, and poverty. To be a total abstainer, that is, to 
refuse to use liquor at any time, requires the courage of 
principle that dares to do right in the face of scorn, a 
kind of courage that may be called the perfection of 
humanity. 
Questions 
1. What is alcohol? 2. Is alcohol a food? 3. What is wood 
alcohol? 4. In what ways is wood alcohol useful? 5. What is the 
effect of wood alcohol on the human system? 6. What law went 
into effect in 1920 regarding intoxicating liquors? 7. How much do 
our people pay yearly for alcoholic patent medicines? 8. What facts 
show that alcohol unfits men for doing their best work? 9. How 
many men in our country formerly drank to such excess as to injure 
health? 10. Give evidence showing that alcohol does not enable 
one to do more work. 11. State ten facts showing that alcohol may 
produce ill health. 12. Why do not drinkers resist disease as well as 
abstainers? 13. Give facts showing that alcohol has much to do 
with poverty. 14. What are the effects of alcohol on offspring? 
15. To what extent does alcohol contribute to crime? 16. When 
may alcohol be considered a poison? 17. Why is it not wise to take 
the first drink in youth ? 
Suggestions for the Teacher 
Prepare three glasses with an inch of soil in each. Moisten the 
soil of number 1 with 5 % denatured alcohol, number 2 with a solu- 
tion of 2 % denatured alcohol, and number 3 with pure water. In 
each plant several seeds of corn, wheat, or beans. Keep the glasses 
covered with a piece of glass, and place them in a light and warm 
room, but not in direct sunlight. Observe the growths during the fol- 
lowing weeks, and ask the pupils to tell what the experiment teaches, XVI. THE EXCRETORY SYSTEM 
Excretions. - The excretions of the body such as sweat 
and urine differ from the secretions like gastric juice and 
saliva in that they are of no further use to the system. 
Every active cell is giving off several substances as a re- 
sult of the life processes. The carbon dioxide is carried 
by the blood to the lungs, and 
through them is expelled. Waste 
flesh is constantly passing out of 
every living cell, and would in a 
few hours poison the body if it 
were not taken up by the capil- 
laries of the circulatory system 
and transported to the kidneys 
and sweat glands to be separated 
from the blood. 
The Kidneys. - These are two 
bean-shaped organs a little longer 
than the middle'finger. They lie 
against the posterior surface of 
the abdominal cavity, one on either side of the backbone 
just below the diaphragm. Any vessel or nerve dis- 
tributed to the kidney is named renal, because the Latin 
word renalis means pertaining to the kidney. The renal 
artery comes direct from the aorta, and the renal vein 
leads the blood to the vena cava. 
Fig. 112. - Human kidney. 
u, ureter. 
175 THE EXCRETORY SYSTEM 
176 
Within the kidney the artery divides like the branches 
of a tree, and each of the thousands of branchlets ends in 
a very tiny ball of capillaries. There are about a half 
million of these balls. Every one of them is enveloped 
by the enlarged end of a minute crooked tube, which 
unites with several of the 
thousands of other similar 
tubes to carry the urine to 
the inner edge of the 
kidney (Fig. 114). Here 
a somewhat funnel-shaped 
cavity, the pelvis, receives 
the urine and lets it pass 
into the ureter. This is 
a tube leading from the 
kidney to the bladder, a 
globular sac which is 
larger than the fist. It 
lies in the lower part of 
the abdomen. 
How the Kidneys Work. 
- In the blood coming to the kidneys, there is much 
water, mineral matter, and waste flesh called urea. By 
the pressure of the blood and the living action of the 
kidney cells forming the fifteen miles of tubes, the water, 
salts, and urea are passed through the blood capillaries 
into the kidney tubes, and thence on to the pelvis, ureter, 
and bladder. Although the nutrition for the tissues is 
in the blood, yet the cells of the kidney tubes prevent 
it from being excreted, and cause to pass through them 
only that which would be harmful if left in the system. 
Fig. 113. - Section of a kidney, ar, 
artery; v, vein ; &, pelvis; u, ureter; 
py, one of the several places where 
the thousands of tubes represented 
by the fine black lines empty into 
the pelvis. THE KIDNEY EXCRETION 
177 
Each cell seems to act with wonderful precision, and 
makes no error unless it is overworked or made sick. 
The Kidney Excretion. - One twenty-fifth of the urine 
consists of solids, and the remainder is water. Of the 
solids more than half 
is composed of urea. 
The amount of broken- 
down flesh passing off 
from the system daily 
in this way is about 
one ounce. The more 
water one drinks, the 
more the kidneys ex- 
crete, and if one uses 
very little water, there 
is sometimes not suf- 
ficient fluid to wash 
properly the waste sub- 
stances from the tissues 
and through the kid- 
neys. Illness then re- 
sults. 
A good preventive 
of rheumatism, and con- 
stipation or clogging 
of the lower bowel, is 
the drinking of much 
pure soft water. A grown person should consume at 
least a quart of milk or water daily, and it would 
result in better health if two quarts of fluid were taken 
daily. 
Fig. 114. - Diagram of the part of the 
kidney between the letters m and n in 
Figure 113. ar, artery; v, vein; t, ball of 
capillaries; n, capillaries. From these 
two sets of capillaries the urine is taken 
into the tube xc and d. 
DAV. PHYS. 12 178 
THE EXCRETORY SYSTEM 
Alcohol and the Kidneys. - When the cells forming the 
tubes of the kidneys become sick, they allow part of the 
albumen of the blood to escape with the urine, resulting 
in serious ill health. This condition is known as inflam- 
mation of the kidneys, or Bright's disease. It is sometimes 
caused by alcoholic drink. It may also be brought on in 
some persons by eating too much meat or other nitroge- 
nous foods for days and weeks in succession, while taking 
but little exercise. It sometimes follows scarlet fever 
and other diseases where there is a great deal of tissue 
waste which must be passed out through the kidneys. 
In any case the cells of the kidneys become sick because 
they are overworked. Bright's disease is twice as com- 
mon now as it was a quarter of a century ago, and scien- 
tists agree that this increase is due in part, at least, to the 
increased use of the light alcoholic drinks. It caused 
nearly 100,000 deaths in the United States in the year 
1905. 
Structure of the Skin.-The skin is composed of two 
layers, known as the cuticle, or epidermis, and the cutis, or 
true skin. The cuticle consists of epithelial cells, the sev- 
eral upper layers of which have no nuclei and are flat. 
The deeper cells are cubical. No blood vessels or nerves 
are present, but every square inch is pierced by a hundred 
or more tubes leading from sweat glands. Under a mag- 
nifying glass, the mouths of these appear as minute pits 
arranged in rows on the little ridges in the palm of the 
hand. The cells on the surface of the epidermis are be- 
ing constantly shed, while new ones are being developed 
from the lower layers. In caterpillars, crabs, frogs, and 
snakes the cells on the surface of the skin hold together STRUCTURE OF THE SKIN 
179 
and are shed in one entire mass. The use of the epider- 
mis is to prevent injuries to the more delicate structures 
beneath and to keep germs from entering the tissues. 
Fig. 115. - Section through the skin, a, dead epidermis; d, live epidermis: 
all below is the derma or true skin, ar, artery seen dividing into capillaries 
again uniting to form a vein; e, sweat glands; f, fat cells; n, nerve endings. 
rriie cutis, or derma, lies beneath the epidermis and 
consists of a tough elastic network of fibers mingled with 
a few cells. In it are numerous capillaries and the end- 180 
THE EXCRETORY SYSTEM 
ings of nerves, some of which are acted on by heat, some 
by cold, and others by touch. The skin is bound to the 
underlying muscles and fatty tissue by a loose elastic 
connective tissue. 
Use of the Skin. - The epidermis prevents injury to the 
more delicate structures beneath. Touching the naked 
nerve endings would cause pain, and contact with rough 
material would destroy them and break the delicate walls 
of the blood capillaries. This may be observed on any raw 
surface. The dry and horny nature of the epithelium 
excludes germs and poisons with which the body frequently 
comes in contact. 
The derma, or cutis, is the seat of the important senses 
of pressure, pain, and temperature. We receive our 
knowledge of pressure and temperature entirely through 
nerve endings in the cutis, but nerve endings for the sense 
of pain are present all over the body. The cutis is also 
an important means of regulating the body heat. When 
the body becomes hot, the capillaries of the skin enlarge 
so that the hot blood can come to the surface and be 
cooled. Evaporation of the sweat also cools the body. 
Injuries to the Skin. - Slight pressure or friction for a 
long time on the skin causes the epidermis to become 
thicker. For this reason it is more than twice as thick 
on the palms of the hands and the soles of the feet as else- 
where. Hard pressure or friction will sometimes produce 
a blister or a corn. A blister, which may also be made by 
the application of mustard or other irritating substance, 
is a portion of the epidermis separated from its deepest 
layer by a collection of lymph having oozed out of the 
underlying vessels. THE SWEAT GLANDS 
181 
A corn is a thickening of a spot of epidermis so that it 
presses on the tissues beneath. The best remedy for a 
corn is to soak the feet in warm water and then with a 
razor or sharp knife pare off the thickened cuticle, being 
careful not to cut deep enough to cause pain. The pres- 
sure of the shoe may 
then be removed by 
pasting on one side 
of the corn a piece 
of thick cloth with 
dried mucilage on 
one surface. Reg- 
ular corn rings may 
be purchased at the 
drug store for the 
same purpose. 
Sometimes large 
areas of skin are de- 
stroyed by burning 
or otherwise. It is 
then necessary to 
cut small bits of 
skin from other parts of the body or from another person's 
body and lay them upon the raw surface. They will 
absorb the lymph diffusing from the capillaries, and the 
cells will multiply in a few weeks so as to cover the naked 
tissues. This is called skin grafting. 
The Sweat Glands. - There are about 2,000,000 sweat 
glands distributed in the deeper layers of the dermis. 
They are thickest in the palms of the hands, on the soles 
of the feet, and on the forehead. Each gland consists of 
Fig. 116. - Mouths of sweat glands. Magnified. 182 
THE EXCRETORY SYSTEM 
a minute coiled tube in the cutis and a duct extending in 
a slightly wavy course through the epidermis to the sur- 
face (Fig. 115). With a magnifying glass these openings 
may be seen in the hand. These glands give forth a fluid 
called perspiration. Their activity is greatly increased by 
heat or exercise. 
Perspiration.-The amount of sweat given out by a 
laboring man in warm weather may be as much as one 
gallon daily. The average quantity excreted by an adult 
is a little less than a quart in twenty-four hours. More 
than ninety-nine per cent of sweat is water. A slight 
amount of urea, common salt, and a few other substances are 
present. The chief use of the perspiration is to control the 
temperature of the body. Heat arouses certain nerves 
which control the sweat glands and makes their excretions 
flow out in larger quantities on the surface of the body. 
Here it evaporates and thus cools the skin. One seventh 
of the heat of the body is lost by the evaporation of the 
sweat. Dr. Zuntz tells of a man who had no sweat 
glands, and was unable to work in the hot weather be- 
cause the temperature of his body became too high. 
Sitting in a wind after sweating often causes a cold. 
The Sebaceous or Oil Glands. - These are present in 
the skin wherever hair occurs, whether it is long, as upon 
the head, or pale and short, as on other parts of the body. 
Each gland, scarcely as large as the point of a pin and 
somewhat like a bunch of grapes, opens by a single duct 
near the top of the sac inclosing the root of the hair. 
The secretion is an oily semiliquid mass which sets, upon 
exposure to the air, into a cheesy mass, as seen in the 
pimples frequently occurring on the face. These pimples BALDNESS AND GRAY HAIR 
183 
may be avoided in many cases by eating but little meat, 
refraining from sweets and pies, and taking much out- 
door exercise. 
The secretion of the sebaceous glands is of some use in 
keeping the skin soft and making the 
hair more pliable. It is, in fact, 
nature's hair oil, and no other dress- 
ing for the hair should be used. 
The glands may be made more 
active by massaging or gentle pinch- 
ing of all parts of the scalp daily. 
The Hair.-The hair is composed 
of minute horny scales and is widely 
distributed over the body. Each 
hair is situated in a tubelike sac 
called the follicle, made by the dip- 
ping down of the epidermis into the 
lower tissues. At the bottom of the 
follicle is a little knob, the papilla, 
made of capillaries and other tissue. 
It is from this papilla that a new 
hair grows as often as the old one is 
pulled out. The little teacuplike 
cavity in the end of the hair fits over 
the papilla, whereby nourishment 
from the blood readily reaches the 
hair (Fig. 117). 
Baldness and Gray Hair. -The falling out of the hair 
does not, except in rare cases, result from bacteria, mi- 
crobes, or any kind of germs, but is due to a lack of 
nourishment furnished by the papilla at its root. If the 
Fig. 117. - Section of the 
scalp, magnified, h, 
hair; w, hair sac; s, 
sebaceous gland; m, 
muscle which may 
sometimes cause the 
hairs to stand erect. 184 
THE EXCRETORY SYSTEM 
papilla is dead, no substance will cause the hair to grow, 
and therefore no attention should be paid to the numerous 
advertisements offering for sale drugs or apparatus that 
will make hair develop on a bald head. The fact that 
Indians and others who never wear close-fitting hats do 
not become bald indicates that the pressure of the hat 
about the head, thereby shutting off to some extent the 
blood, may be one cause of baldness. Another cause may 
be the exclusion of fresh air from the head. 
Dandruff commonly results from an unhealthy condi- 
tion of the cells of the scalp. This may be remedied by 
washing the scalp thoroughly with tepid water and any 
good toilet soap weekly or bi-weekly. The soap should be 
well washed out with soft water, and the hair then dried as 
quickly as possible. The tendency to baldness is often 
hereditary, and frequently nothing will prevent it. In 
many cases, the hair, when beginning to fall out, may be 
invigorated by massaging, that is, pinching and wrinkling 
together various portions of the scalp a few minutes daily. 
Fright, anxiety, or great care may turn the hair gray in 
a few weeks or even a single night, but usually the gray 
color appears gradually after the age of forty. It is due 
to air taking the place of the pigment in the central por- 
tion of the hair. There is no way of preventing the hair 
from becoming gray except by dyeing it frequently, a pro- 
cedure which usually injures the hair and sometimes the 
general health. 
The Complexion. - The great difference in the com- 
plexion of persons is due largely to the pigment lying in 
the lower part of the epidermis. In negroes there is 
much of the pigment, and it is very dark. In people of THE COMPLEXION 
185 
light complexion only a little pigment is present. Tan- 
ning is the temporary development of extra pigment 
influenced by the rays of the sun. 
The skin cannot be made soft, beautiful, and white 
by means of paints and 
powders. Some of them 
contain poisons, such 
as arsenic, and more- 
over they are likely to 
clog the openings of the 
glands, eventually giv- 
ing an ugly complexion. 
Washing the skin with 
soft water and soap, 
eating fruits instead of 
sweetmeats, drinking 
much water or lemon- 
ade, taking plenty of 
exercise in the open air, 
and keeping the mind 
free of evil thoughts 
by thinking good ones are certain aids in producing a 
pleasing complexion and countenance. 
Hair growing on the face or in other regions where it 
is not wanted can be permanently removed only by means 
of the electric needle. Therefore, it is foolish to give 
heed to any of the numerous offers made by quacks in the 
newspapers to sell a drug that will permanently remove 
hair. The preparations so much advertised usually con- 
tain a compound of sulphur, which will dissolve the hair 
on the surface but will not kill the roots. If applied 
Fig. 118. - Hand, showing the effects of 
chewing off the finger nails. 186 
THE EXCRETORY SYSTEM 
several times, the skin becomes very sore and the hair 
tends to become thicker. 
The Nails. - The nails are hardened epidermis. They 
protect the ends of the fingers if they are not cut too 
short. The very bad habit of chewing off the ends of the 
nails causes short and blunt fingers. The nails should 
be filed off every morn- 
ing even with the finger 
tips, and the dirt should 
be removed from be- 
neath the nails each time 
after washing the hands. 
Growths on the Skin. 
Warts are overgrowths 
of the epithelial cells. 
Their cause is not 
known. They are not 
harmful and may be 
easily removed by a 
physician, but are in no 
way affected by any 
words a fortune teller 
can say. Moles are slight elevations of the epidermis 
containing an increased growth of hair. They are usually 
inherited. 
Cancer is probably not, as was once thought, the result 
of germs growing in the tissues, but is due to the cells of 
the body becoming deranged. They multiply rapidly and 
consume the other tissues, eating away blood vessels and 
nerves, so that in a year or two death often results. Can- 
cer is not contagious. No one should pay any attention 
Fig. 119. - Hand, showing nails properly- 
cared for. THE COLD BATH 
187 
to the numerous advertisements by doctors offering to cure 
cancer. Many tumors are called cancers and are easily 
cured, while some cancers cannot be cured by any means. 
Reliable physicians and surgeons never advertise cures. 
It is best to follow the advice of the family physician. 
The Hot Bath. - Cold water will not cleanse the body 
thoroughly, and therefore every one should bathe the 
entire body at least once a week in hot water, using soap 
and friction to remove not only dirt but also the outer 
dead skin likely to clog the pores. Such bathing is an aid 
to health and a preventive of the unpleasant odors given 
off from an uncleanly body. The feet and certain other 
portions of the body should be washed daily to be kept 
odorless. The proper time for a hot bath is at night, as 
the heat draws the blood away from the brain, makes it 
less active, and tends to produce sleep. The bath should 
not be taken just after a meal, as the blood is drawn 
away from the digestive organs to the surface of the 
body. 
The Cold Bath. - The hot bath may be taken as hot as 
one can bear it, but the cold bath should be from about 
sixty-eight to seventy-eight degrees. The most favorable 
time for a cold bath is immediately upon rising in the 
morning or just after exercising, when the body is warm. 
It should not last longer than one or two minutes, after 
which the body ought to be briskly rubbed with a rough 
towel. If a tub or regular shower bath cannot be had, 
almost equal results may be reached by standing in a wash 
bowl or small tub and pouring the cold water on the 
shoulders and letting it run down over all parts of the 
body. 188 
THE EXCRETORY SYSTEM 
Cold bathing is of great use in treating patients with 
nervous disorders or consumption, and in the healthy it 
tones up the system, and is a great preventive of colds if 
taken daily. Within a few minutes after leaving the 
cold bath, reaction should occur, when the capillaries and 
small arteries enlarge, the skin flushes, and there is a 
general sense of warmth and well-being. 
Swimming and Bathing. - Swimming is one of the most 
helpful forms of exercise. It should, however, usually 
not be indulged in more than once a day, and then for a 
period not exceeding a half hour. When one is jumping 
about or swimming, the heat produced by the muscular 
exercise counteracts the effect of the cold water on the 
skin. 
It is the duty of every one to learn to swim. The 
census report shows that during the years 1900 to 1904 
about 40,000 people lost their lives by drowning. The 
ability to swim would doubtless have saved a large per- 
centage of these. It is important to remember that there 
is danger in going into the water to swim when one is 
very tired, as the weary muscles are likely to go into 
cramps. The safest plan is never to go alone into water 
over one's head. Swimming just before, or sooner than 
two hours after, a heavy meal is unwise. 
Clothing and Health.- The chief use of clothing is to aid 
the body in keeping a constant temperature and thus pre- 
vent sickness. Woolen clothing is warmer than cotton or 
linen clothing because it contains many meshes or tiny 
open spaces filled with air. This air prevents the escape 
of heat from the body. Therefore the clothing for cold 
weather should generally be of wool. Since woolen goods ALCOHOL AND THE SKIN 
189 
de not absorb and pass off the sweat so quickly as cotton 
or linen cloth, the clothing worn next to the skin by vig- 
orous and healthy persons should consist of loosely woven 
cotton or linen material for all seasons. As the clothing 
worn next to the skin absorbs the excretions coming from 
the sweat pores, it should be frequently washed. It is 
wise to change the underclothing weekly in winter and 
twice weekly in summer. 
The body can be made comfortable while out-of-doors 
in cold weather, by wearing an overcoat or wrap. The 
feet should be protected from the wet by rain-proof shoes 
or overshoes. One should never sit in wet clothing but 
exercise until it can be exchanged for dry garments. 
Alcohol and the Skin. - Repeated indulgence in the use 
of alcoholic drink makes the skin of the face puffy, and 
may give to it a blotched appearance, so characteristic 
of the confirmed drunkard. Alcohol enlarges the arteries 
and capillaries of the skin, and thus makes the face red, 
and in cold weather cools the body very rapidly, because 
so much of the warm blood is brought to the surface. In 
health seventy-five per cent of the heat leaving the body is 
lost by passing off from the capillaries of the skin. The 
use of alcohol may increase this loss of heat by ten per cent. 
The shivering fits on recovery from drunkenness, which 
frequently occur, are due to the fact that the body has lost 
a considerable amount of heat. The lowering of the tem- 
perature of the body by alcoholic drink may result in death. 
During a very cold night in winter several of a group of 
men, camping in the mountains in the West, drank consid- 
erable whisky before retiring, and as a result froze to 
death. Those who refrained from drink survived. 190 
THE EXCRETORY SYSTEM 
Questions 
1. What are excretions ? 2. Describe the kidneys. 3. How do the 
kidneys work? 4. Why should much water be drunk? 5. Ex- 
plain the effect of alcohol on the kidneys. 6. Describe the epidermis. 
7. Describe the cutis. 8. Of what use is the skin ? 9. How does a corn 
differ from a blister ? 10. Describe the sweat glands. 11. State five 
facts concerning perspiration. 12. Describe the oil glands. 13. What 
may cause baldness? 14. Give the cause and cure for common 
dandruff. 15. How may the complexion be improved ? 16. Describe 
the care of the nails. 17. Why should one never employ a doctor ad- 
vertising to cure cancer? 18. Of what use is a hot bath? 19. How 
often and when should a hot bath be taken ? 20. Why should most 
people take a cold bath daily ? 21. What care should be observed 
when swimming ? 22. Explain the influence of alcohol on the skin. 
Suggestions for the Teacher 
The teacher should take this opportunity to impress upon the 
pupils the necessity of personal cleanliness, and the importance of 
caring properly for the nails and hair. Some of the pupils may be 
asked to give their personal experience in reference to the benefit 
derived from the hot and cold baths. 
To show that wool is more serviceable than cotton in keeping 
the body warm, heat two small tin cans of water. Wrap around one 
a piece of cotton cloth and around the other a piece of woolen cloth 
weighing the same as the cotton cloth. Let the pupils note the 
difference in temperature by touching the water in each can at the 
end of a half hour or more. 
To prove that wet clothing cools the body quickly, secure two 
pieces of cotton cloth of the same size and two jars of warm water 
Wet one cloth and wrap it around one of the jars and put the other 
cioth dry about the other jar. At the end of a half hour test with 
the finger which jar of water is the cooler. The teacher may save 
some of the children from many colds and serious sickness by im- 
pressing upon them the danger of sitting still while the clothing is wet. XVII. THE OSSEOUS SYSTEM, OR BONES 
The Use of Bones. - The bones of the body are neces- 
sary for its support and also to enable it to move. The 
muscles, which are made to act by the nerves, pull upon 
some of the bones so as to move them in various ways. 
The bones protect the vital organs, such as the brain, 
spinal cord, lungs, and heart. All the red blood cor- 
puscles, and many of the white ones, are made in the red 
bone marrow, occupying a portion of the interior of the 
bones. 
The Parts of the Skeleton. - There are about 200 bones 
in the body. These joined together in their natural rela- 
tions form the skeleton. It is divided into the skull, or 
bones of the head, trunk, and extremities, according to the 
table given on the next page. 
The cranium is composed of the bones surrounding the 
brain, while the other bones of the head form the face. 
The spinal column is not a single bone, but is constructed 
of a chain of 24 bones, called vertebrce, in addition to the 
sacrum and coccyx formed of vertebrae grown together. 
Within a canal extending through the vertebrae lies the 
spinal cord. The same bones present in the human 
skeleton are also found in the dog or cat, and therefore 
the skeleton of these animals often discovered in the 
woods or fields may be used for study. 
191 192 
THE OSSEOUS SYSTEM, OR BONES 
Fig. 121. - Side view of ver- 
tebral column and skulL 
See description below. 
Figs. 120-121. - a, tarsals; c, meta- 
carpals; cl, clavicle; f, femur; Ji, fib- 
ula; h, humerus; i, innominate or 
hip bone; k, patella or kneecap; m, 
metatarsals: p, phalanges; r, radius; 
s,sacrum; t,tibia or shin bone; u,ulna. 
7, frontal bone; 2, parietal; 3, occip- 
ital ; 6, orbital cavity; 7, temporal 
bone; 8, maxillary; 9, malar; 16, 
mandible; 37, cervical or neck verte- 
brae ; 40, dorsal or thoracic vertebrae : 
41, lumbar vertebrae; 42, sacrum; 
43, coccyx; 38 and 39, spines of axis 
and atlas. 
Fig. 120. - Human skeleton. See 
description in next column. KINDS OF BONES 
193 
Table of Bones 
frontal 1 
parietal 2 
temporal 2 
occipital 1 
ethmoid 1 
sphenoid 1 
Cranium 
The Skull 
or 
Bones 
of the 
Head 
nasal 2 
inferior turbinated 2 
lachrymal 2 
maxilla or upper jaw 2 
mandible or lower jaw 1 
palate 2 
malar or cheek bone 2 
vomer 1 
Face 
hyoid 1 
Spinal column 
or- backbone 
Other bones of 
the trunk 
vertebra 24 
sacrum 1 
coccyx 1 
Bones of the 
Trunk 
sternum or breast bone 1 
ribs 24 
innominate or hip bone 2 
Shoulder girdle 
Arm 
Forearm 
Wrist 
Hand 
Fingers 
clavicle or collar bone 2 
scapula or shoulder blade 2 
humerus 2 
Bones of the 
Upper 
Extremity 
radius 2 
ulna 2 
carpal 16 
metacarpal 10 
phalanges 28 
femur or thigh bone 2 
tibia or shin bone 2 
fibula 2 
patella or knee pan 2 
Bones of the 
Lower Ex- 
tremity 
Leg 
Ankle 
Foot 
Toes 
tarsal 14 
metatarsal 10 
phalanges 28 
Kinds of Bones. - Tn respect to shape, there are five 
groups of bones : they?a£ bones, such as those of the cra- 
nium, the shoulder blade, and the ribs ; the irregular bones, 
including the ethmoid, sphenoid, and vertebra); the short 
DAV- PHYS 1.8 194 
THE OSSEOUS SYSTEM, OR BONES 
bones, represented by those in the 
wrist and ankle; the long bones, 
composed of a hollow shaft and 
two enlarged ends, such as those 
in the leg and arm; and the 
sesamoid bones, like the patella, 
formed in the region of joints by 
friction or pressure. The number 
of sesamoid bones increases in 
accordance with age and the 
amount of physical labor done. 
Composition of Bone. - Bone is 
composed of animal and mineral 
matter, the latter of which is 
chiefly phosphate and carbonate 
of lime. By placing a slender 
bone from any animal in water 
containing one tenth part of nitric 
acid or hydrochloric acid, the 
mineral matter 
will be so com- 
pletely dissolved out in four days 
that the bone will be as limber as 
cartilage. From another bone the 
animal matter may be removed by 
burning it a half hour in the stove, 
after which it will be so brittle as to 
crumble into dust at the touch of 
the fingers. 
The Parts of a Bone. - All the 
bones are covered with a tough con- 
Fig. 122. - A,leg. B, arm. 
a, tarsus; c, carpus; cl, 
clavicle; m, metacarpus: 
mt, metatarsus; p, pha- 
langes ; s, scapula. 
Fig. 123. - Rib from 
which the mineral 
matter has been dis- 
solved by acid. THE PARTS OF A BONE 
195 
nective-tissue membrane, named 
the periosteum. This serves for 
the attachment of tendons and 
muscles, and has the power of 
renewing any portion of bone 
removed by the surgeon on ac- 
count of disease or accident. 
The bony tissue itself is of 
two kinds. One is called com- 
pact or hard lone, and the other 
is the cancellous or spongy bone. 
The outer part of the skeleton 
is made of compact bone, but 
it forms a very thin layer, 
except in the long bones, where it makes nearly all of 
the shaft, or middle 
part, between the en- 
larged extremities. 
The cancellous tissue 
is abundant in the 
interior of all bones, 
except the long ones, 
where it is chiefly 
present only at the 
ends. The shaft con- 
tains a cavity known 
as the medullary 
canal. This is oc- 
cupied by the medulla, 
or white marrow. It 
is largely made of fat. 
Fig. 124. - Upper part of the 
femur cut open to show 
c, compact tissue; cn, 
cancellous tissue; I, med- 
ullary canal. 
Fig. 125. - Thin slice of bone half the size 
of the cross section of a pin. The two 
white circles are Haversian canals, and the 
black spots are lacunae or spaces for the 
living bone cells. Photographed through 
the microscope. 196 
THE OSSEOUS SYSTEM, OR BONES 
The Structure of Bone. - If a slice is sawed from a 
bone and ground very thin on a whetstone, it will pre- 
sent under the microscope many circular openings, called 
Haversian canals, which in life contained blood vessels 
and nerves. The 
numerous small 
holes in the sur- 
face of a bone are 
for the entrance of 
vessels and nerves 
to the Haversian 
canals. Irregular 
oval spaces, the 
lacunce, with fine 
radiating channels 
are arranged in 
circles about the 
Haversian canals. 
Each lacuna in live 
bone is filled with 
a cell, which is 
nourished by the 
blood escaping from 
the vessels in the 
Haversian canals 
(Fig. 125). 
The Development 
of Bone. - Most of the bones, except those forming 
the top and sides of the skull, are developed from 
cartilage. This is a tough white substance, commonly 
called gristle. It may be easily bent and pressed out 
Fig. 126. - X-ray view of the hand of a child five 
years of age. Only three of the eight bones of 
the wrist are formed and many of the end pieces 
of the other bones are not united to the shafts. 
Photographed by Dr. W. W. Seibert. THE DEVELOPMENT OF BONE 
197 
of shape. In the young child, since much of the 
cartilage is not yet changed into bone, the legs may be- 
come bent or bowed if it is allowed to stand too much. 
In older children, during the first years of school, the 
thigh bones may be 
given a permanent 
curve backward if 
the seat is so high 
that the feet cannot 
touch the floor. 
The ends of most 
of the long bones 
are joined to the 
shaft by cartilage 
only until the six- 
teenth year, or even 
later. At birth the 
skull is quite in- 
complete on the 
sides and top, so 
that between the 
bones are six spaces 
where only mem- 
brane separates the 
brain from the skin. 
These are not completely closed by bone until near the 
end of the second year, so that a slight stroke on the 
head of a young child might prove very serious. Unless 
the clothing about the waist of children is worn loose, 
the bones of the thorax may be pressed in so as to pre- 
vent the internal organs from doing their work. 
Fig. 127. - X-ray view of the hand of an adult. 
Photographed by Dr. W. W. Seibert. 198 
THE OSSEOUS SYSTEM, OR BONES 
Broken Bones. -A break m a bone is called & f racture. 
As the bones of children bend easily, they are seldom 
broken off completely, but are cracked somewhat like a 
tough stick when bent. This is known as a green-stick 
fracture. When the bone of an older person is broken, 
the ends usually separate some- 
what, owing to the pull of the 
muscles. In order to set the 
bone properly, the two ends 
must be brought together and 
held firmly in place by a thin 
board or sheet of metal band- 
aged on the limb. No one 
but a good physician is capable 
of setting a broken bone success- 
fully. However, if a person 
with a fracture must be moved 
from the place of accident, it 
is wise to hold the broken bones 
in place by binding firmly on 
either side of the fracture, en- 
veloped in clean cloth or cotton, 
a narrow board or flat stick. 
When the parts of the bone 
broken render little injury to the flesh, the fracture 
is said to be simple. A compound fracture is one in 
which the ends of the bone protrude through the 
skin. In young persons broken bones usually knit 
together in three or four weeks, but in persons over 
sixty years of age healing sometimes requires several 
months. 
Fig. 128. - Femurs which were 
fractured. The one on the 
right was not properly cared 
for, and the ends have pushed 
over each other. DISEASE OF BONES 
199 
Disease of Bones. - The com- 
monest disease of bones is 
tuberculosis, caused by the 
growth of a minute plant, the 
consumption germ. White 
swelling, hunchback, curvature 
of the spine and hipjoint dis- 
ease may result from bone 
tuberculosis. It is the most 
frequent in children fed on the 
raw milk of diseased cows or 
living in daily contact with a 
person suffering from consump- 
tion. It has lately been found 
that many cases can be cured by 
good food and fresh air, especially along the seashore. 
The first of the sea- 
shore sanatoria needed 
to treat the 60,000 
children in this country 
suffering from bone tu- 
berculosis was estab- 
lished in 1906. 
A felon is an inflam- 
mation of the perios- 
teum, caused by bacteria 
finding entrance and 
developing. Rickets 
occur in children not 
sufficiently nourished 
to permit the deposit 
Fig. 129.- Temporary bandage 
for a broken bone until the 
surgeon arrives, n is a piece 
of board, and a similar piece 
is on the back of the arm. 
Fig. 130. - Hip bone and end of the thigh, 
to show the character of a joint. 200 
THE OSSEOUS SYSTEM, OR BONES 
of enough mineral matter in the bones to render them 
hard. 
The Joints. - The juncture of two or more bones is a 
joint, or articulation. The two general classes of joints 
are the movable and immovable. The immovable joints 
occur between the bones of the 
skull, and are often called sutures. 
The two important kinds of mov- 
able joints are the ball and socket 
joint, like that at the shoulder and 
hip, and the hinge joint, as seen at 
the knee and elbow. 
In the movable joints the adja- 
cent ends of the bones are covered 
with a thin pad of cartilage, and 
several tough inelastic bands of 
white fibrous connective tissue, 
called ligaments, hold the bones in 
place, and form about the space 
between the ends of the bones a 
capsule. This is lined with a deli- 
cate membrane, called the synovial 
membrane (Fig. 131). It secretes 
from the blood a thick fluid, the synovia, similar to the 
white of egg. This glairy fluid is necessary to keep 
the joint moist. 
Strain and Sprain. - By bending a joint too far or push- 
ing the end of a bone to one side, the ligaments may be 
stretched and slightly torn, resulting in swelling and ten- 
derness, called a strain. A severe strain is a sprain. The 
best immediate treatment is to immerse the injured part 
Fig. 131.-Diagram of 
a section through a 
joint. The hones are 
shown more separated 
and the cartilage 
thicker than in nature, 
c, cartilage; I, liga- 
ment ; s, synovial 
membrane. 201 
NARCOTICS AND BONE GROWTH 
in hot water or wrap it in cloths wrung out of hot water, 
and change them every few minutes. At the end of a 
half hour the joint should be massaged by rubbing it 
toward the body in order to move the collected lymph 
away to the veins. Unless the ligaments are torn, com- 
plete rest is not so helpful as careful exercise and frequent 
massaging. 
Dislocation of Bones. - When at a joint the end of one 
of the bones is forced backward, forward, or to one side 
of the other bone so far that it does not slip back into 
place, it is said to be dislocated. The ligaments may be 
torn or greatly stretched. The services of a physician 
are usually necessary to remedy the difficulty. The bones 
at the knee and shoulder joints are the ones most fre- 
quently dislocated, and fortunately are often quite easily 
put in place by a strong pull on the limbs. 
Narcotics and Bone Growth. -The bones derive material 
for they? development from the food eaten. When the 
food has reached the stomach and intestine, it must be 
properly digested before it can be absorbed and carried 
through the body to build up the bones. Alcoholic drinks, 
soothing sirups for children, and tobacco have a tendency 
to diminish digestion. They, therefore, in some degree 
prevent the proper food supply from reaching the bones. 
When the bone-building cells of the body are ever so 
slightly stupefied by narcotics of any kind, they fail to 
take from the blood and use what is needed to make sound 
bones. Evidence is gradually accumulating which indi- 
cates that the stunted frames of some children in alcoholic 
families are due in part at least to the effects of alcohol. 
On this account, beer should never be given to children 202 
THE OSSEOUS SYSTEM, OR BONES 
Questions 
1. Of what use are the bones? 2. What are the three parts of the 
skeleton? 3. Point out on your head the two parts of the skull. 
4. Point out the location of five bones of the cranium. 5. Point out 
five bones of the face. 6. Of what is the vertebral column formed? 
7. Give the number of ribs. 8. Name five bones in your upper ex- 
tremity. 9. How many phalanges in each finger ? 10. Wherein does 
the arrangement of the bones of the leg differ from that in the arm ? 
11. Give the composition of bone. 12. State five facts concerning the 
parts of a bone. 13. From what are bones developed ? 14. Explain 
how broken bones should be cared for. 15. Why should a heavy strain 
not be put upon the bones of the young ? 16. Point out on your body 
and name three kinds of joints. 17. Describe the parts of a joint. 
18. How should a sprain be treated? 19. What is meant by the dis- 
location of a bone? 20. How does alcohol affect bone growth? 
Suggestions for the Teacher 
1. Ask a pupil to procure from a butcher a bone about a foot long, 
sawed lengthwise. Observe in class the periosteum, the red marrow, 
the white marrow, and the two kinds of bony tissue. 
2. Secure from the butcher a joint. Look for the ligaments unit- 
ing the bones, by tearing away all muscle and fat. Cut open the joint 
and note the few drops of sticky synovial fluid and the transparent 
synovial membrane as thin as tissue paper on the inside of the liga- 
ments. 
3. Ask one pupil to show on another's arm how a fracture is to be 
treated when the patient must be moved before the arrival of the 
surgeon. XVIII. THE MUSCULAR SYSTEM 
The Parts. - The muscular 
system, like the other systems, 
is composed of parts or organs, 
each of which is a muscle. 
The muscle is the lean meat 
of the body and is made of a 
tissue which has the property 
of contracting or becoming 
shorter in length while its 
thickness increases. This 
change in shape is produced 
by a peculiar chemical action, 
resulting from a stimulus pass- 
ing from the nervous system 
to the muscle. We can send 
this stimulus to most parts of 
the muscular system at will, 
and the muscles thus made to 
act are named voluntary. We 
cannot, however, control by 
our will the muscles helping 
to form the walls of the blood 
vessels, stomach, and intes- 
tines, and on this account they 
are known as involuntary 
muscles. 
Fig. 132. - Muscles and tendons 
on the back of the arm. 
203 204 
THE MUSCULAR SYSTEM 
The Involuntary Mus- 
cles. - They are often 
called plain or unstri- 
ated muscles, because of 
the smooth appearance 
of the cells seen under 
the microscope. The 
muscles in the skin 
and in nearly all of 
the tubes of the body 
are involuntary. The 
movements of the 
stomach and intestines 
and the contraction of 
the blood vessels helping to regulate the heat of the 
body are produced by the involuntary muscles. The 
will has no control 
over them, but when 
food comes into the 
intestines, it affects 
the endings of nerves 
there which are 
aroused to action, 
and the stimulus 
goes to the cells of 
the spinal cord, caus- 
ing them to send 
out a stimulus to 
make the muscles of 
the intestines act. 
Cold, acting on the 
Fig. 133. - A tiny bit of involuntary mus- 
cle magnified to show the cells, n, 
nucleus. 
Fig. 134. - A bit of voluntary muscle as thick 
as a hair magnified to show the striations of 
fibers. Photographed through the microscope. THE IS ATU RE OF A VOLUNTARY MUSCLE 
205 
nerves, causes the muscles in the skin to contract and 
produce the rough goose flesh often seen on the bare 
arm after a cold bath. 
The heart is made of involuntary muscle, but the cells, 
being short, thick, and striped, are quite different from 
those of the other in- 
voluntary muscles. 
The Nature of a Vol- 
untary Muscle. -What 
is usually spoken of 
as flesh or lean meat 
is composed of the 
voluntary or striated 
muscles. There are 
about 400 of them 
in the human body. 
They are of a reddish 
pink color, and each 
one is surrounded by 
a transparent sheath 
which is joined to the 
adjacent muscles. 
The important ele- 
ments of a muscle are the fibers, which have the shape of 
rods. They vary in length from less than a quarter 
of an inch to over two inches, and are so slender that 
a dozen of them together would not be as thick as 
a hair. The fibers are easily seen by tearing into bits, 
in a drop of water on a glass slide, a small piece of beef 
or other muscle, and examining it with the microscope. 
Between the fibers are numerous arteries, capillaries, and 
Fig. 135. - Action of biceps muscle, b, 
extended; a, contracted; h, humerus; 
s, scapula. 206 
THE MUSCULAR SYSTEM 
veins for the purpose of supplying oxy- 
gen and food, and taking away the 
waste resulting from the life processes. 
The Use of Muscles. - The chief func- 
tion of the muscles is to produce motion 
in any part of the body. Usually the 
ends of a muscle are attached to dif- 
ferent bones, so that when it contracts 
one of the bones must move. Several 
of the muscles attached 
to the bones of the 
fingers have their 
other ends fixed on 
the humerus (Fig. 
136). The muscles 
pulling on the femur 
have an attachment on 
the hip bone. A mus- 
cle is able to contract 
nearly one fourth of 
its length. 
The contracting muscles serve an 
important purpose in pressing upon 
the veins and lymphatics so as to move 
their contents, which must always go 
toward the heart on account of the 
valves in the vessels. Other uses for 
the muscles are to protect the blood 
vessels and nerves from injury and add 
beauty and symmetry to the form of 
the body. 
Fig. 136. - Flexor 
muscles on the 
front of the fore- 
arm with ten- 
dons at the wrist. 
Fig. 137. - Muscles 
on the front of the 
thigh, v, a, and i 
are the three parts 
of the quadriceps 
extensor. I, hip 
bone. THE ARRANGEMENT OF THE MUSCLES 
207 
The Arrangement of the Muscles. - In some regions of 
the body only a single layer of muscles covers the bones, 
while in other parts as many as three layers occur. 
Usually a muscle is attached to two different bones, but 
one end may be 
fastened to the skin 
or another muscle, 
and in some cases 
one end of the mus- 
cle is divided into 
several parts. The 
end of the muscle 
fixed on the bone 
which it moves is 
called the insertion, 
while the other end 
is the origin. The 
masseter, or chewing 
muscle, has its origin 
on the cheek bone 
and its insertion on 
the mandible. 
In some cases the 
muscle fibers join 
directly to the peri- 
osteum of the bone, but in others a tough white cord, 
called a tendon, apparently continuous with the muscle 
fibers, occurs at either or both ends of the muscle to con- 
nect it to the bone. The largest is the Achilles' tendon, 
which feels like a hard cord a half inch thick just above 
the heel. Several tendons may be felt in the wrist. 
Fig. 138. - Some of the muscles used in breath- 
ing. a, muscles under the scapula; e, car- 
tilage part of the rib; A, humerus; m, 
muscles pulling on the ribs when the arms 
are thrown backward; n, intercostal muscles; 
r, rib; s, sternum. 208 
THE MUSCULAR SYSTEM 
Kinds of Muscles. -• In reference to the action effected, 
the muscles are divided into five groups : 1. the fiexors 
are those which bend a limb; they occupy the palm side 
of the hand and arm, and the back of the leg (Fig. 136) ; 
2. the extensors straighten a limb, and therefore lie on 
the side of the limbs 
opposite to the flexors 
(Fig. 132) ; 3. the ab- 
ductors pull a limb or a 
part of a limb outwards, 
as when the arms are 
stretched outward on 
either side ; 4. the ad- 
ductors oppose the ab- 
ductors, as seen in the 
action of the pectoral 
muscles of the chest 
when drawing the arm 
across the breast; 5. 
the sphincters are ring- 
like muscles and sur- 
round openings, such as 
the mouth and the eye. 
The score of muscles 
controlling the eyes, 
mouth, and other features of the face are the muscles of 
expression, and on their action depends largely whether one 
has a pleasing or unattractive countenance. In one who is 
accustomed to pout, frown, or cry about every trifle, the 
muscles become so trained to pulling down the corners 
of the mouth, pushing out the lips and wrinkling the 
Fig. 139. - Portrait showing how the 
shoulders are rounded and the chest com- 
pressed, thus inviting tuberculosis. EXERCISE 
209 
forehead that the face can never have a pleasant aspect. 
Persons called homely are often the most delightful com- 
panions because of their pleasant looks and kind words, 
helping every one to wear a smile. 
A charming expression can be culti- 
vated by any one. 
The diaphragm and most of the 
other muscles attached to the ribs are 
concerned in respiration, because it 
is only when the diaphragm is pulled 
down or the ribs drawn up that the 
pressure is decreased in the chest so 
as to cause the air to flow into the 
lungs. The muscles of locomotion 
are those controlling the legs. 
Exercise.-No one can remain in 
good health very long without tak- 
ing some form of exercise. If one's 
regular work does not compel him to 
move nearly all of the muscles of the 
body, he must devise some plan that 
will bring the muscles into action. Neither a gymnasium 
nor expensive apparatus is necessary for the best form of 
exercise, though they are great aids in influencing the 
young in the right direction. The playing of some game 
in the open air, such as paper chase, and swimming, row- 
ing, climbing trees, botanizing, and studying nature, are 
splendid ways of bringing all muscles into play. A 
tennis court well used will save doctor's bills. 
Round shoulders, narrow chests, diseased lungs, slug- 
gish liver, and constipation may be prevented or remedied 
Fig. 140.-Ungraceful 
attitude preventing the 
full expansion of the 
lungs. 
DAV. PHYS. 14 210 
THE MUSCULAR SYSTEM 
by exercise regularly taken. A good position in stand- 
ing and sitting and a graceful carriage in walking should 
be practiced both for health and appearance. The droop- 
ing of the shoulders and the projecting of the chin and 
abdomen are common faults in young people. Exercise 
and fresh air have cured ten times 
more cases of consumption than all 
medicines combined. It is not over- 
study that breaks one down and 
causes nervous prostration, but lack 
of exercise and fresh air. One of 
the most important parts of the 
treatment for the sick in sanatoria 
consists of certain forms of exercise. 
Massaging. - This process consists 
in pinching, pressing, squeezing, and 
kneading the muscles, skin, and in- 
ternal organs in such a way as to 
cause the lymph with its collected 
impurities to pass away and the 
organs to become more active. A 
massage has somewhat the same 
effect as exercise. The circulation 
is stimulated, and the tissues purified. It likewise has 
a very beneficial effect on the nervous system. To 
massage most efficiently, one should have special train- 
ing from an expert, but almost any one, with a little 
practice, can accomplish much in relieving pain and 
sleeplessness by rubbing and kneading the muscles so 
as to force the lymph and impure blood toward the 
heart. 
Fig. 141. - A graceful 
and restful position 
conducive to health. HOW ALCOHOL AFFECTS THE MUSCLES 
211 
Tobacco and the Muscles. - Nicotine causes the invol- 
untary muscles of the small blood vessels to contract, and 
thus shut off some of the nourishment intended for the 
growth of the muscles. The habitual use of tobacco 
affects the growth of the young in a very marked degree. 
At Yale University during four years the non-users of 
tobacco gained 24 per cent more in height and 26.7 per 
cent more in the girth of the chest than the habitual 
users of tobacco. Dr. Seaver, of New Haven, found, on 
examining a large number of young men, that the tobacco 
users at 18 years of age were not so large and well devel- 
oped as the non-users only 17 years old. That the use 
of tobacco dwarfs the ycung there is no doubt. 
For perfect control of the muscles there must be a per- 
fect nervous system. The nerve cells of the young are 
very delicate structures and cannot perform their duties 
accurately when dulled by such a poison as nicotine. 
Professor Drawing, of the Naval Academy, says that 
smokers are not able to control their muscles accurately, 
and he can discover the tobacco users by their inability to 
draw a straight line or hold the hand perfectly still. 
How Alcohol affects the Muscles.- Alcohol may stimu- 
late the muscles for a few minutes somewhat in the same 
way that a whip urges forward a horse, but recent experi- 
ments all agree in showing that the daily amount of work 
accomplished by men using alcohol is always less than that 
done by the total abstainers. On this account no athlete 
while in training makes use of whisky, wine, or beer. 
Soldiers on forced marches are found to make better prog- 
ress when denied the use of alcohol and given beef tea. 
Brigadier General A. W. Greely says that it should be 212 
THE MUSCULAR SYSTEM 
strongly urged that no alcoholic drink be used by soldiers 
undergoing great physical hardship and frequent exhaust- 
ing labor. 
Scientists, as a result of recent investigations, are unani- 
mous in the opinion that a man can run faster, shoot 
straighter, and lift more without the use of alcohol than 
he can by using it in either small or large quantities. 
Sir Frederick Treves, in speaking df his experiences in the 
Boer War, says: "It is also curious that troops cannot 
work or march on alcohol. I was, as you know, with the 
relief column that moved on to Ladysmith, and, of course, 
it was an extremely trying time by reason of the hot 
weather. In that enormous column of 30,000, the first 
who dropped out were not the tall men, or the short men, 
or the big men, or the little men-they were the drinkers, 
and they dropped out as clearly as if they had been 
labeled with a big letter on their backs." The excessive 
use of beer tends to change the muscle cells of the heart 
into fat, so that the organ finally becomes weakened 
sufficiently to refuse to act, and sudden death results. 
Questions 
1. What special property is possessed by muscle? 2. Where are 
involuntary muscles found? 3. How are muscles made to act? 
4. Give two features of involuntary muscles. 5. Explain the nature 
of voluntary muscle. 6. Of what use are muscles? 7. Explain the 
meaning of origin, insertion, and tendon. 8. Point out on your body 
and name four kinds of muscles. 9. Why does the expression of the 
face depend upon the muscles? 10. Explain how and why the mus- 
cles should be exercised. 11. Describe massaging and its effects. 
12. How does tobacco affect the muscles? 13. Give facts showing 
that tobacco is injurious to muscular development. 14. How does 
alcohol affect the muscles ? 15. How many muscles in the body ? SUGGESTIONS FOR THE TEACHER 
213 
Suggestions for the Teacher 
1. The leg of a frog or chicken in which the muscles have been 
loosened from each other by cutting the connective tissue uniting them 
may be prepared by the teacher or some of the older pupils and kept 
permanently for demonstration. Ask the pupils to note the difference 
between the muscle and tendon, and how the muscle or tendon is joined 
to the bone. 
2. Observe through the skin the three tendons on the front of the 
wrist, and by working the fingers and thumb determine where the 
tendons are inserted. 
3. Require the class to perform some simple gymnastic exercises 
helpful in preventing round shoulders and flat chests. Call the 
attention of the pupils to the graceful positions in walking and 
standing. 
4. When possible, it will prove of great interest and value to have 
a trained nurse or physician show the pupils how to massage and 
produce most helpful results in such simple ailments as a slightly 
sprained wrist or a stiff neck. Fig. 142. - The nervous system, c, cerebellum; the large nerve of the 
leg is the sciatic; the white line down the back is the spinal cord. XIX. HOW THE NERVOUS SYSTEM IS 
CONSTRUCTED 
Parts. - The nervous apparatus of the body may be 
considered in three parts : the central nervous system, in- 
cluding the brain and spinal cord ; the nerves, extending 
from the brain and 
cord to all parts of 
the body ; and the 
sympathetic system, 
composed of bunches 
of cells, chiefly in 
the body cavity, 
with their nerves 
supplying the 
glands, and the in- 
voluntary muscle in 
the entire body. 
The nervous system 
bears the same re- 
lation to the organs 
of the body as the 
manager of a large establishment, with the telephone wires 
leading to all departments, does to the workmen. The 
brain and spinal cord direct the other organs as to the 
amount of work to be done, and the time to do it. 
The Brain.-The brain fills loosely the cavity of the 
skull, in which it is securely fastened and protected by 
Fig. 143. - The brain in the skull, with its 
upper half removed. Membranes of the brain 
are taken off to show the convolutions ap- 
pearing as folds separated by the sulci. 
215 216 
HOW THE NERVOUS SYSTEM IS CONSTRUCTED 
three membranes, named the dura mater, arachnoid, and 
pia mater. The dura mater is tough and sticks closely to 
the skull, while the other two are very delicate. The pia 
mater, carrying blood vessels, dips down into all crevices 
of the brain. These crevices are known as sulci, and the 
larger ones, being an inch or more deep, are named fissures. 
. The irregular convex portion 
of matter between any two 
sulci is a convolution (Fig. 
144). 
The brain is in communi- 
cation with all parts of the 
body by means of white 
cords, the nerves. Some of 
them branch in several 
places from the lower side 
of the brain, and extend to 
the head and neck, while 
others at the back part of 
the brain unite into a large bundle, called the spinal 
cord. This extends down the back within the inch- 
wide canal of the vertebrae, and gives off between the 
bones of the spinal column branches leading to the arms, 
trunk, and legs. 
The Parts of the Brain. - The three parts of the brain 
most clearly marked off on the surface are the medulla 
oblongata, or medulla, the cerebellum, or little brain, and the 
cerebrum, or forebrain. 
The medulla is the stem or bulb joining the higher parts 
of the brain with the spinal cord. With it are connected 
eight pairs of nerves distributed chiefly to the head. 
Fig. 144. - The brain from the side, 
ce, cerebellum; c, spinal cord; m, 
medulla oblongata; p, pons Va- 
rolii; s, fissure of Sylvius in the 
cerebrum. 217 
THE CEREBRUM 
The cerebellum, almost as large as one's fist, lies above 
and back of the medulla. Its surface is marked by deep 
cuts or sulci, forming plates of matter. The cerebellum 
is united to the other 
parts of the brain and 
the spinal cord by 
several bands of nerve 
fibers. The middle 
part of one of these 
is the pons Varolii, ap- 
pearing as a flat band 
on the lower side of 
the brain just in front 
of the medulla. 
The cerebrum is di- 
vided incompletely by 
the great longitudinal 
fissure into two equal 
parts, called hemi- 
spheres. They are 
connected with each 
other at the base and 
also with the other 
parts of the brain and 
cord by means of nerve 
fibers (Fig. 146). 
The Cerebrum. - Each hemisphere is divided into five 
indistinct parts, called lobes, and named according to the 
bones of the skull nearest them. 
The two chief fissures, in addition to the great longi- 
tudinal one between the hemispheres, are the fissure 
Fig. 145. - View of the brain from beneath, 
showing a dozen pairs of cranial nerves 
cut off. oi, olfactory tract, or roots of the 
nerve of smell, bearing at the end the 
bulb; op, the nerve of sight; oc, band 
of fibers connecting the cerebrum with 
the cerebellum and spinal cord; a, pons 
Varolii; h, medulla oblongata. 218 
HOW THE NERVOUS SYSTEM IS CONSTEUUTEO 
of Sylvius, above the ear, and the fissure of Rolando, 
extending from the crown 
obliquely forward and down- 
ward. 
The General Structure of the 
Brain. - A section across the 
brain shows it to be composed 
of a thin outer layer of gray 
matter, called the cortex, and 
near the center other masses 
of gray matter, while the re- 
mainder appears white. Ex- 
amination with the microscope 
shows that the gray matter is 
composed of very irregular, 
spherical, or oval cell bodies 
from which extend threadlike processes, called fibers, 
forming the white matter. 
Each cell body with all its 
processes is a true nerve cell, 
or neuron. There are usually 
several short processes, and 
frequently one long process, 
the axon, called by the older 
books axis cylinder process 
(Fig. 148). Some of the 
axones are more than two feet 
long and extend from the brain 
to near the end of the spinal 
cord. Axones are commonly 
called nerve fibers. Those which cross from one side of 
Fig. 146.-The brain from above, 
showing the two hemispheres 
separated by the great longi- 
tudinal fissure. 
Fig. 147. - Cross section of the 
brain, c, band of fibers called 
corpus callosum. The thin 
membrane around the outside 
is the dura mater. Note the 
dark layer of gray matter or 
cortex on the surface. 219 
THE STRUCTURE OF THE SPINAL CORD 
the brain to the other and connect parts of the same name 
form bands, known as commissures, like the pons Varolii. 
The largest commissure is the corpus callosum, uniting the 
hemispheres of the cerebrum. Other fibers connect one 
lobe of the cerebrum with another. 
The Spinal Cord. - The spinal cord is securely fastened 
in the upper three fourths of 
the canal of the backbone. 
It is about as thick as the 
little finger, and is surrounded 
by other membranes like those 
of the brain. It is round, 
except in the shoulder and 
lumbar region, where it is 
slightly flattened. In these 
two places it is also enlarged, 
owing to the great number of 
nerve fibers joining it from 
the arms and legs (Fig. 142). 
A deep crevice, the anterior 
fissure, extending the entire 
length of the cord in front, and a similar - incision, the 
posterior fissure, incompletely divide the cord into 
halves. 
The Structure of the Spinal Cord. - A cord cut into 
crosswise shows two kinds of matter like that in the brain. 
The white substance, formed of fibers, is on the outside, 
while the central portion of the cord is gray matter, which 
in cross section appears H-shaped. This gray matter is 
made of the body of the nerve cells. These cells send 
many of their axones, or long processes, out to help form 
Fig. 148. - A complete nerve cell, 
or neuron, ax, long process 
cut off; n, nucleus. 220 
HOW THE NERVOUS SYSTEM IS CONSTRUCTED 
the nerves supplying the arms, trunk, and legs. Some of 
the fibers forming the white matter of the cord convey 
messages toward the brain, while others carry messages 
in the opposite direction. On any fiber the message 
always travels in the same direction. 
Fig. 149. - Cross section of the spinal cord, showing nerve roots on one side. 
ag, anterior horn of gray matter; pg, posterior horn of gray matter 
(nerve cells are black; the tiny circles are the ends of nerve fibers ex- 
tending lengthwise of the cord); ps, sensory root; an, motor root (these 
two roots unite before coming out between the vertebrae); c, cell body 
whose fiber a extends to the finger; m, fiber extending to the finger 
(arrows show the direction of the impulse; only a few of the thousands of 
fibers actually present are shown); v, ventral fissure; d, dorsal fissure. 
Kinds of Nerves. - The cranial nerves, of which there 
are twelve pairs, are those united to the base of the brain. 
The spinal nerves, numbering thirty-one pairs, join the 
spinal cord. Some of the nerves are for the purpose of 
transmitting orders from the central nervous system to 
the muscles, and are therefore called motor nerves. The 
Sensory nerves carry messages from various parts of the 221 
CRANIAL NERVES 
body to the spinal cord and 
brain. The nerve leading 
from the retina of the eye 
is a sensory nerve, while 
the nerve extending from 
the brain to the muscles 
to move the eye is a 
motor nerve. Frequently 
motor and sensory fibers 
are bound together in the 
same nerve, as is the case 
in all those nerves con- 
nected with the spinal 
cord. 
Cranial Nerves. - All of 
the twelve pairs of cranial 
nerves, with the exception 
of one pair, supply the 
head, neck, or upper part 
of the shoulders. They 
are numbered from before 
backward according to the 
order in which they are 
joined to the brain. They 
are also named according 
to their function or in ac- 
cordance with the region 
which they supply. The 
first pair of cranial nerves 
are the olfactory, or nerves 
of smell, and the second, or 
Fig. 150. - View from the side of part 
of the sympathetic nervous system 
within the body cavity. The white 
lines are nerves, a, spinal nerves to 
the arm; h, heart; i, intestines; n, 
ganglia, or bunches of cell bodies on 
the sympathetic nerve cord ; p, one of 
the four large plexuses of the sym- 
pathetic system ; t, stomach ; 10, tenth 
cranial nerve to lungs and stomach. 222 
HOW THE NERVOUS SYSTEM IS CONSTRUCTED 
optic, are the nerves of sight. The eighth pair are the 
auditory nerves, leading from the ear. 
Spinal Nerves. - All the 31 pairs of spinal nerves 
contain both motor and sensory fibers. Each nerve is 
united to the cord by two branches, named roots, the back 
one of which is the dorsal root, and the front one is the 
ventral root. If the dorsal root of a spinal nerve is cut, 
the part of the body supplied by the nerve is without 
feeling, while if the other root is cut the muscles it sup- 
plied cannot be moved (Fig. 149). 
The Nerves to the Limbs. - About 200,000 fibers are 
present in the nerves in the upper part of the arm. The 
two largest nerves are the median and the musculo-spiral. 
A continuation of one division of the median nerve along 
the radius is the radial nerve, and the other division along 
the ulna is the ulnar nerve. 
Usually the larger nerves, veins, and arteries lie to- 
gether, and are not near the surface. The ulnar nerve, 
however, is so near the surface at the inner side of the 
elbow that it is often struck. It is then usually said that 
the funny bone has been hit, because of the queer feeling 
in the ends of the fingers to which the nerve extends. 
Several spinal nerves in the lumbar region are united by 
fibers to form a network or plexus, from which branches 
are distributed to the legs. The largest nerve of the leg 
is the sciatic. 
The Sympathetic Nervous System.-The sympathetic 
nerves connect all internal organs with the central ner- 
vous system and supply the glands and involuntary mus- 
cles of the entire body. This system consists of three 
parts; 1. a nerve cord uniting 23 ovoid ganglia, lying on SUGGESTIONS FOR THE TEACHER 
223 
either side and somewhat in front of the spinal column; 2. 
numerous fibers extending from these two main cords and 
ganglia to the viscera, on which they form networks, called 
plexuses; 3. many fine fibers which accompany the spinal 
and cranial nerves to supply the glands and involuntary 
muscles throughout the body (Fig. 150). 
This system is connected with the main nervous system 
by numerous branches. The will has no direct control 
over the sympathetic nerves, which, against one's wish, 
may refuse to make the gastric juice run or may relax the 
muscles of the arteries and produce blushing. 
Questions 
1. Give the three parts of the nervous system. 2. What is the re- 
lation of the brain and spinal cord to the rest of the body ? 3. Ex- 
plain the terms sulci, fissures, and convolutions. 4. What connects the 
brain with other parts of the body? 5. Give the parts of the brain. 
G. Describe the cerebellum. 7. Give four features of the cerebrum. 
8. What part of a neuron composes the gray matter of the brain? 
9. Explain axon. 10. What is a commissure? 11. Give the size and 
location of the spinal cord. 12. Of what use are the nerve fibers ? 
13. Why are some nerves called cranial and others spinal? 14. flow 
does a motor nerve differ from a sensory? 15. Name the cranial 
nerves of sight, smell, and hearing. 16. To what parts do most of the 
cranial nerves extend ? 17. Explain how a spinal nerve is attached 
to the cord. 18. State five facts concerning the nerves to the limbs. 
19. Over what nerves does the will have no control ? 20. To what 
organs do the nerves of the sympathetic system extend? 
Suggestions for the Teacher 
1. The brain of a calf or sheep may be secured from the butcher. 
Request him to break it as little as possible in removing it from the 
skull and to leave the membranes on. Note the tough dura mater 
which should be cut loose with the scissors. The two other membranes 
are so thin that the brain may be seen through them. Note that the 224 
HOW THE NERVOUS SYSTEM IS CONSTRUCTED 
convolutions are much fewer than in the human brain, and that the 
cerebrum does not cover the cerebellum. Observe the depth of 
the fissures and the white and gray matter, seen by cutting through 
the brain. On the under side look for the two bands of fibers diverg- 
ing in front of the pons Varolii, the one going to the right and the 
other to the left hemisphere. Through these, impulses travel to and 
from all parts of the body. The brain may be hardened so that it can 
be sliced, by dropping it into the formaldehyde solution for a week. 
2. A piece of the spinal cord of a sheep or pig may be had for 
the asking at the butcher shop. The arrangement of the white and 
gray matter is easily seen, and if care is used in removing the cord, the 
nerve roots may also be seen. The nerves may be studied in the hind 
leg of a frog or of a chicken, where they appear as white glistening 
cords as thick as a pin or thicker. 
3. The interest of the pupils may be greatly increased and lasting 
impressions may be made by showing with a microscope a thin slice 
of the brain or spinal cord. If the school has no microscope, a physi- 
cian may usually be found in every locality who will take pleasure in 
showing the children the wonderful cells upon which every thought 
and movement depend. XX. HOW THE NERVOUS SYSTEM WORKS 
The Use of Nerve Cells. - It is by means of the nervous 
system that all parts of the body are made to work har- 
moniously. The muscles are directed when to act, and the 
stomach makes known its needs by messages sent through 
the nerve fibers to the cord and 
brain. How the message travels 
no one knows, but it goes very 
quickly. The time required to send 
a message from a man's toe to the 
brain and back again is about one 
third of a second. The processes 
of the nerve cells serve the same 
purpose as the telegraph wires of a 
railway, but the bodies of the nerve 
cells are of two kinds. Those in the 
spinal cord and medulla are like the 
telegraph operator, and can send only 
such messages as are given them. 
The cell bodies in the cortex of the brain are like the 
manager of the railway, and can form the message in 
themselves, and then direct the nerve cells in the lower 
parts of the brain and in the cord to send it to a part 
of the body. How these cells in the cortex of the brain 
are related to the mind is not known. 
Fig. 151. - Nerve cell 
from the cortex of the 
brain, a, axon, which 
may extend to the end 
of the spinal cord. 
Magnified. 
DAV. PHYS. - 15 
225 226 
HOW THE NERVOUS SYSTEM WORKS 
How the Brain Acts. - Each part of the brain has its 
own work to do. The medulla oblongata is the only por- 
tion of the brain whose destruction causes immediate 
death. A knife may be run through the cerebrum and 
all of the cerebellum cut away without fatal results. The 
cells in the medulla 
control the breathing 
and the heart beat, 
and also have much 
to do with the motion 
and secretions of the 
alimentary canal. 
The use of the cere- 
bellum is not well un- 
derstood. Animals in 
which it is injured can 
move the muscles, but 
they are unable to 
contract at the same 
time and in the right 
degree the score or 
more of muscles nec- 
essary for any act, 
such as walking. As 
a result they tumble about like a drunken man. This 
inability to make the muscles act in harmony is lack of 
coordination of muscular movements. 
The Use of the Cerebrum. - The cerebrum is the seat 
of the mind. All processes of thought depend upon the 
nerve cells in this portion of the brain. That part of the 
cortex along the front of the fissure of Rolando is called 
Fig. 152. - Skull cut away to show parts of 
the brain used for various purposes, c, 
cerebellum; rr, fissure of Rolando; I, cells 
moving the leg; a, cells moving the arm; 
h, cells moving the hand; f, cells moving 
the muscles of the face; t, cells receiviug 
the impression of touch; v, cells used in 
seeing; e, cells used in hearing. WHAT THE SPINAL CORD DOES 
227 
the motor area, because the cell bodies here are able to 
produce motion in all voluntary muscles of the body (Fig. 
152). A slight knock on top of the head causes one 
to fall down, because the cells of the motor area are 
stunned. Most of the long processes of these cells extend- 
ing down through the brain cross over to the opposite side 
in the medulla to form part of the white matter of the 
spinal cord. Therefore an injury to the left hemisphere 
affects the muscles on the right side of the body. 
The sensory area is along the posterior side of the 
fissure of Rolando. The cells of this region receive the 
impulse aroused in the skin by pressure, heat, and cold. 
Destruction of all the sensory area makes one insensible to 
heat, cold, and touch. The area for sight is in the cortex 
of the back part of the cerebrum. If this is destroyed 
one cannot distinguish by sight a ball from a top or 
a butterfly from a wasp, because the cells which told 
the mind the visible characters of those things are 
gone. 
The area for hearing is in the temporal lobe, and near 
by are the cells concerned in smelling and tasting. 
What the Spinal Cord Does.-The cord serves two pur- 
poses. It is a path of communication between the nerves 
supplying the arms, trunk, and legs, and the brain. An 
impulse to kick starts from the brain's motor area, formed 
by cell bodies, and passes along their processes down the 
spinal cord to the lumbar region. Here another set of cell 
bodies receives the message, and through their processes 
forming part of the sciatic nerve carries it to the muscles 
of the leg. 
The second function of the cord is to act independently 228 
HOW THE NERVOUS SYSTEM WORKS 
of the brain and produce many of the muscular movements 
necessary in routine work. This is spoken of as reflex 
action (Fig. 153). 
Reflex Action. - This is any action of the nervous sys- 
tem without the use of the will. Tickling the foot of the 
soundest sleeper causes it to be moved, but the brain is 
asleep and the will did not act. The cells in the cord 
aroused by the tickling sent a message to make the mus- 
cles move. The squirming of a snake with a mashed 
head, the jumping of a chicken with its head cut off, and 
the wriggling of the pieces of a freshly cleaned eel placed 
in the hot frying pan are reflex acts in which the brain 
can have no part. 
Reflex action causes the hand stuck with a pin to be 
withdrawn before the brain can act. The stimulus travels 
up the nerve fibers of the arm and through the sensory 
cells of the dorsal root, then out their processes to pass 
over to the motor cells in the spinal cord. These cells are 
thus aroused to send the message to the muscles to con- 
tract. A twentieth of a second later the brain is aware 
of the pin, because the sensory fibers, upon entering the 
cord, split and send branches also up toward the brain 
(Fig. 153). 
The Use of the Sympathetic System.-The working of this 
system consists of a series of reflex actions. These nerves 
control the involuntary muscle in all parts of the body. 
They help govern the movements of the intestines and 
the heart beat, and determine the amount of blood sup- 
plied to various parts of the body by contracting or 
loosening the muscle in the walls of the small arteries. 
This system regulates the activity of the sweat glands Fig. 153. - Diagram of reflex action. - Arrows show which way the impulse 
is traveling; n, spinal nerves. When the finger is pricked by a tack t, the 
nerve ending p receives the pain impulse and it is carried along the fiber 
a through the sensory root arouud into the spinal cord. Here the impulse 
is given to the cell m, and its fiber then conveys the impulse down the arm 
to the muscle causing the finger to be withdrawn. The sensory fiber 
passing in atpo splits inside of the cord, and one branch takes the message 
to the brain. Here it passes to the motor cells, which may order the 
finger held still or withdrawn. 230 
HOW THE NERVOUS SYSTEM WORKS 
and influences the secretion of the salivary glands, and 
causes the flow of tears. 
Paralysis and Apoplexy. - Paralysis is inability of the 
nerves to act because of injury to the cell bodies or the 
processes. The breaking of a blood vessel in the brain or 
cord, so as to produce a clot to press on the cells or fibers, 
will cause paralysis in those parts of the body to which the 
fibers help convey impulses. The growth of a tumor in 
the brain or the pressing of a bone on nerves may also 
result in paralysis. Apoplexy is quick paralysis, usually 
brought on by the bursting or clogging of a blood vessel 
in the brain. 
How the Uses of the Brain have been Determined. - 
Since the dog, rabbit, pigeon, frog, and all other animals 
with a backbone possess the five parts of the brain ar- 
ranged in the same order as in man, much information 
about the use of the brain has been secured by experi- 
menting on the lower animals. In these creatures, put to 
sleep by drugs, the effects of stimulating the nerves have 
been noted, and the influence of all parts of the nervous 
system on the various organs learned. Other knowledge 
has been derived from studying those sick with nervous 
ailments, and then, after death, cutting open the bodies to 
see exactly where the cause of the trouble was. Much of 
the physiology of all organs has been learned from the 
study of the lower animals. Experiments on them have 
given the doctors information enabling them to save 
thousands of human lives and a vast amount of suffering. 
Brain Weight and Intellect. - The brain is smaller in 
women than in men because the body is smaller. The 
average weight of the male brain is three pounds and two WHY THE BRAIN NEEDS EXERCISE 
231 
ounces, while that of the female is two pounds and twelve 
ounces. In mental workers the brain grows until the 
age of 40 years, and after the age of 50 it loses about one 
ounce during every 10 years. The brain of those doing 
the same work from day to day, such as shoveling coal or 
working in a factory, so that the mind is not kept active, 
ceases to grow after the twentieth year of age. 
A good mind does not depend so much upon the size of 
the brain as upon the development of the processes of the 
nerve cells. In a general way, however, the size of the 
cerebrum and especially the number of the convolutions 
and the depth of the sulci indicate the degree of intelli- 
gence in animals. A man's brain is larger than that of 
any other creature, except the elephant and the whale. 
A whale weighing 12,000 pounds has a brain only 10 
ounces heavier than the brain of a man weighing 120 
pounds. 
Why the Brain needs Exercise. - A muscle grows by 
use, and the same is true of the brain. In the young 
there are many nerve cells with short processes or none at 
all. The processes may be made to develop by exercising 
the cells, as when one studies. Thinking causes the blood 
to flow to the brain, and so brings more nourishment for the 
cells. To express a thought in one's own language is worth 
ten times more for mind growth than to state it in words 
learned from the book. 
Observing the features of a bird and then striving to 
identify it from the description in the book, or noting the 
characters of a cow so as to tell her value compared with 
other cows, develops important brain cells and is worth 
vastly more than memorizing a half-dozen pages in a 232 
HOW THE NERVOUS SYSTEM WORKS 
book. Professor Donaldson, who examined the brain of 
naura Bridgman deprived early of sight and hearing, says 
that the nerve cells in the sight and hearing areas of the 
brain were much smaller than those in other persons. 
Like the other tissues, the brain, upon which the mind de- 
pends, grows faster in youth, and no amount of exercise 
will make it develop late in life. On this account one 
should hold steadfastly to school while young. 
Habits. - The doing of one thing over and over again 
calls into action the same set of nerve cells, and they 
finally become so accustomed to act that they do so with- 
out the aid of the will and often even against it. This is 
habit. A boy long accustomed to swearing, acting rudely, 
eating rapidly, or looking sullen cannot refrain from these 
ungentlemanly habits later in life, even when honestly try- 
ing to do so. The cultivation of agreeable manners and 
pleasant looks not only makes friends in school, but makes 
success in later life. Evil thoughts passing often through 
the cells leave a blot there which can never be entirely 
erased. The first step toward wrong doing is in wrong 
thinking. Many cases are known where the reading of 
books and newspapers describing wicked acts has affected 
the nerve cells so as to cause the reader to commit robbery 
and other crimes. 
The youth who causes to pass through his nervous 
system into the mind noble thoughts from good people 
and good books, and who learns industry, patience, and 
politeness, is sure of friends and success in life. The 
mind is like a piece of ground which, if not sowed with 
good seed and cultivated, will grow up with worthless 
weeds. It is therefore important that one should keep 233 
THE NERVOUS SYSTEM AND TOBACCO 
the mind busy in doing what will yield the right kind of 
harvest. 
Sleep. - It is just as important to rest as to work. 
The only time when the nervous system rests completely 
is during sleep. Adults, as a rule, should sleep eight 
hours every night, while those younger should add fifteen 
minutes for every year under the age of twenty. Loss of 
sleep is sure to result in ill health sooner or later. The 
time for retiring should be the same every night, so 
that one will drop off to sleep within five minutes after 
lying down. Without the advice of a physician medicine 
should never be taken to produce sleep. Placing the feet 
in hot water a few minutes, taking a hot bath, or a half 
glass of hot milk is an aid to sleep. 
The Nervous System and Tobacco. - Tobacco habitually 
used by the young has a more serious effect on the ner- 
vous system than on any other part of the body. It pre- 
vents the brain cells from developing to their full extent 
and results in a slow and dull mind. Justice Brewer, 
of the United States Supreme Court, says: "No ciga- 
rette smoker can attain the highest position in the world." 
At Harvard University during fifty years no habitual 
user of tobacco ever graduated at the head of his class. 
The New York Division of the Reading Railroad, which 
prohibits cigarette smoking by employees, says: " Men who 
smoke cigarettes are liable to lapses of memory, and it is 
not safe to trust the lives of passengers in the hands of 
men who have that failing." 
Recent careful investigations by many persons show 
that cigarette smoking not only clouds the intellect, but 
tends to make criminals of boys. Dr. Hutchison, of 234 
HOW THE NERVOUS SYSTEM WORKS 
the Kansas State Reformatory, says: "Using cigarettes 
is the cause of the downfall of more of the inmates of this 
institution than all other vicious habits combined." Of 
4117 boys received into the Illinois State Reformatory, 
4000 were in the habit of using tobacco, and over 3000 
were cigarette smokers. 
It is unwise to begin the use of tobacco, because when 
the habit is once acquired it can be broken only by one 
with a strong mind who is willing to endure suffering 
caused by the longing nerve cells during the first few 
weeks after being deprived of their accustomed poison. 
How Alcohol affects the Nervous System. -Much of the 
alcohol consumed is absorbed by the blood vessels of the 
stomach, so that it reaches the nerve cells in a few minutes. 
A large amount of alcohol paralyzes them, as may be 
judged by the actions of a reeling drunken man. In 
many persons a half teacupful of strong wine will affect 
the brain perceptibly. 
A drink of whisky or wine may help one to talk more, 
because it removes the careful judgment which one 
should give a thought before he utters it. On this ac- 
count persons, after drinking, often reveal secrets and 
say very silly things. All late investigators declare that a 
student can perform more mental work in a day without 
alcohol than he can by the aid of either small or large 
quantities of any alcoholic drink. The excessive use of 
alcoholic drinks, whether pure or impure, may cause delir- 
ium tremens. This is a severe poisoning of the nerve cells, 
resulting in trembling, weakness, and great fear. Often 
the victim thinks he sees horned animals, spitting insects, 
and snakes. HOW ALCOHOL AFFECTS THE NERVOUS SYSTEM 
235 
The continued use of liquor in many cases produces a 
gradual change in the nerve cells so as to affect the mind 
and cause a tendency to crime. This fact is very clearly 
shown by the careful investigations of the Committee of 
Fifty, who inquired into the history of 13,402 convicts, 
and ascertained that intemperance was a strong factor in 
the downfall of over 6000 of them. Alcohol was the 
first cause of crime in over 4000 of these convicts. The 
government report of Massachusetts states that one sixth 
of all of the crime in that state is due solely to alcohol. 
Russia reports that one fourth of her crime results from 
alcohol. Intemperance causes a little over one half of the 
crime in England. 
The mind cannot be strong and sound when the brain 
cells are being constantly injured by large daily doses of 
beer, wine, or whisky. Numbing the cells of the brain or 
affecting them in any way by alcoholic drink always has 
some influence on the mind. The reports of the Com- 
missioners of various insane asylums show that nearly 
one fourth of the male persons confined in them owe 
their insanity to alcohol. The report of the Waterford 
Lunatic Asylum in Ireland for 1903 states that the most 
frequent cause of insanity of those admitted was in- 
temperance. 
The poisonous effects of alcohol on the nervous system 
of the parent are in many cases transmitted to the chil- 
dren. Havelock Ellis says that some of the most charac- 
teristic cases of criminality in children are solely or 
chiefly due to the use of strong drink by the parents. 
Dr. Keer reports that in one family after the birth of 
a healthy son and later a healthy daughter, the father HOW THE NERVOUS SYSTEM WORKS 
236 
became a drunkard. Of the four children born after this, 
three were idiots. 
Professor Hodge, of Clark University, tells of 10 alco- 
holic families in which there were 57 children, and only 
ten of them were healthy. Some were idiots and some 
were epileptics. There are about 200,000 idiots and epi- 
leptics in the United States, and it is probable that some 
of them owe their condition to the drunkenness of their 
parents. During the next ten years after the spirit tax 
was removed in Norway, drunkenness increased markedly 
and the proportion of idiots born increased 150 per cent. 
Scientific investigations confirm the warning of the Scrip- 
ture : " The sins of the parents shall be visited upon the 
children even unto the third and fourth generation." 
Questions 
1. How do the nerve fibers differ in function from the cell bodies ? 
2. Explain the use of the medulla. 3. What work does the cerebellum 
perform? 4. Upon what part of the brain does thought largely de- 
pend? 5. What is meant by motor area? 6. Explain the sensory 
area. 7. What are the two uses of the spinal cord ? 8. Explain reflex 
action. 9. What causes paralysis? 10. How have the uses of the 
different parts of the brain been learned ? 11. Give some facts con- 
cerning the weight of the brain. 12. What elements in the brain 
determine the making of a good mind? 13. How can one increase 
the amount of nourishment carried to the brain? 14. Why should 
you not memorize the words of your lesson? 15. Why is it important 
to exercise the brain in youth? 16. What habits are dangerous and 
why? 17. State five facts about sleep. 18. What effect has alcohol 
on the nervous system ? 19. Explain the cause of delirium tremens. 
Suggestions for the Teacher 
Ask some of the pupils to tell how they have been able to stop some 
bad habits, such as chewing the finger nails, speaking in a loud and 
rude manner, or frowning. XXT. THE SENSE ORGANS 
The Nature of the Sense Organs. - The sense organs are 
the terminations of the sensory nerves serving to carry 
impressions to the spinal cord or brain. They are the 
means by which all messages of information get on to 
the nerves to be carried to the central nervous system. 
One's knowledge of an apple is secured through certain 
sense organs in the skin touching the apple, through the 
sense organs in the nose affected by the odor of the apple, 
through the sense organs in the tongue aroused by its 
sweetness, and through the sense organs of sight stimulated 
by the light reflected from the apple. None of these im- 
pulses excited in the sense organs can give rise to sensa- 
tions until they reach the brain. A man had his back 
broken so that the bones pressed on the cord, preventing 
its nerves from carrying any message up to the brain. 
When his feet were tickled, the legs would jump about, 
showing that the sense organs of the skin had sent the 
stimulus up the nerves to the cord, exciting an impulse in 
the motor cells there, but the man said he felt no touch on 
the feet. No sensation of tickling was produced, because 
the impulse received by the organs of sense could not 
reach the brain. 
The Kinds of Senses.-Two general classes of senses 
are known. The interior or general senses are those tell- 
ing a person of the condition of the body. To this class 
237 238 
THE SENSE ORGANS 
belong the senses of hunger, pain, thirst, and fatigue. 
The exterior senses are the special senses, such as those 
of temperature, pressure, smell, taste, hearing, and sight. 
The senses of temperature, pressure, and pain, which the 
older books call the sense of touch, are now known to be 
just as different from each other as sight and hearing. 
The Senses of the 
Skin.-These are 
often called cutaneous 
senses and include 
temperature, pressure, 
and pain. There are 
certain nerves with 
their special endings 
scattered throughout 
the skin to receive 
the stimulus of cold, 
and an entirely dif- 
ferent set of nerves 
and sense organs to 
receive the knowl- 
edge of heat. The 
sharp point of an icicle can be placed on certain very 
small spots of the skin without any cold being felt, 
because the sense organs for cold are in many places a 
quarter of an inch or more apart. 
The sense organs for pressure are the nerve endings 
around the roots of hairs, and where these are absent 
minute oval bulbs, called tactile corpuscles, occur. A hair 
cannot be disturbed ever so gently without a sensation 
of touch or delicate pressure. The lining of the alimeu- 
Fig. 154. - Section of the skin showing various 
kinds of nerve endings at om, m, e, and a; 
h, hair. THE SENSE OF SMELL 
239 
tary canal below the mouth does not possess any sense 
organs of temperature or pressure, and therefore the 
movement of the food is not felt except when sickness 
makes the end organs of pain more sensitive. 
The sense of pain has separate nerves with their organs 
of sense widely dis- 
tributed throughout 
the body. This sense 
is of great service in 
telling an individual 
when any of the 
organs are sick or 
are being injured. 
Freezing or an ap- 
plication of cocaine 
numbs the sense 
organs of pain and is 
often used in opera- 
tions by the surgeon. 
The Sense of Smell. 
- The sense organs 
of smell are located 
in the mucous mem- 
brane lining the upper part of the cavity of the nose. 
They consist of hundreds of long columnar cells, each ot 
which bears on its outer end from six to eight hairlike 
processes. Particles of matter in the form of gas, 
striking these processes, send a stimulus by the olfactory 
nerves to the brain, producing the sensation of smell. 
A cold excites a secretion of mucus in the nose so as 
partly to cover the organs of smell, and also results in an 
Fig. 155. - Section through the nose, a, dis- 
tribution of the nerve of smell connected 
with ol, the olfactory lobe lying beneath the 
fore part of the brain. 240 
THE SENSE ORGANS 
inflammation of the membrane bearing them, so that they 
are not able to act. During a cold many foods seem to 
have little taste, because it is the odor rather than the 
taste that gives the desired quality to some eatables. 
The pleasure from eating onions, coffee, and cheese will 
be greatly lessened 
if one holds his 
nostrils shut. 
The Sense of 
Taste. - The end 
organs for taste 
occur in the mucous 
membrane of the 
tongue, soft palate, 
and other regions of 
the throat. They 
are minute oval 
bodies, called taste 
buds, each of which 
is connected with a 
nerve fiber extend- 
ing to the brain. 
The taste buds are most abundant in the dozen or less 
circumvallate papilloe, at the back of the tongue, and in 
the fungiform papilloe, appearing as white dots all over 
the top of the tongue (Fig. 91). 
A substance can arouse the sense of taste only when in 
the form of a liquid or dissolved in a liquid. It is im- 
portant that all food should be chewed many times and 
dissolved as completely as possible in the mouth so as to 
affect the taste buds. This causes the gastric juice to 
Fig. 156. - Section through one side of a large 
papilla on the tongue, showing five taste buds 
and the nerve of taste, n. 241 
THE SENSE OE HEARING 
flow abundantly. Careful experiments teach that chew- 
ing each mouthful thirty times will do more to cure 
dyspepsia than all medicines combined. 
The Sense of Hearing. - The organs of hearing are the 
ears. Each one consists of three parts, named the external 
Fig. 157. -Temporal bone cut open to show the bony internal ear. c, coch- 
lea ; v, vestibule; sem, semicircular canals; m, middle ear; d, malleus; 
t, tympanic membrane; n, auditory nerve. The internal and middle ear 
are shown about double natural size. 
ear, the middle ear, and the internal ear. The external 
ear is composed of the pinna, projecting from the side of 
the head, and the tube, an inch long, called the auditory 
canal, extending inward. Across the inner end of the 
canal is a thin membrane, named the tympanic membrane. 
The cavity of the middle ear, or tympanum, also called 
ear drum, is nearly large enough to contain three pennies 
standing close together on their edges. It contains air 
DAV. PHYS. - 16 242 
THE SENSE ORGANS 
which may pass in and out through the Eustachian tube 
leading to the throat. The mouth of the tube is usually 
closed, but it opens every time a bit of food or even saliva 
is swallowed. Three bones, the malleus, or hammer, incus, 
or anvil, and stapes, or stirrup, form a chain stretching 
from the tympanic membrane to another membrane 
closing an oval opening into the internal ear (Fig. 
157). 
The internal ear, or labyrinth, is composed of several 
irregular connected cavities in the temporal bone contain- 
ing within them correspondingly shaped membranous sacs 
supporting the end organs of the nerve of hearing. The 
three parts of the internal ear are the vestibule, cochlea, and 
the three semicircular canals. The bony cavities are filled 
with a watery fluid, called perilymph, serving to float the 
delicate membranous parts containing a similar fluid, the 
endolymph. 
The fluid in the bony vestibule about the size of a pea 
is separated from the cavity of the tympanum at one place 
by a mere membrane to which is fixed the foot of the stapes. 
The semicircular canals are bent tubes placed at right 
angles to each other. They have nothing to do with hear- 
ing, but enable one to balance the body and know its posi- 
tion even with the eyes closed. 
The cochlea, so named from its resemblance to a snail 
shell, is a coiled tube having three coils, with those nearer 
the center becoming successively smaller and more ele- 
vated. On the interior of the membranous cochlea is 
located the sense organ of hearing, consisting of columnar 
cells with hairlike processes projecting into the endo- 
lymph. DEAFNESS 
243 
How Sound is Heard. - The striking of a hard object, 
the crack of a gun, or any other similar action disturbs 
the air and causes in it waves like the waves produced in 
water by a stone cast into a quiet pool. The sound waves 
are vibrations of particles of air which knock against the 
delicate tympanic membrane. This causes motion in the 
chain of bones of the middle ear, and these in turn trans- 
mit the vibration to the perilymph of the inner ear, touch- 
ing the membrane attached to the foot of the stapes. 
The waves in the perilymph beat on the delicate mem- 
branous part of the cochlea, and thus make vibrations in 
the endolymph which affect the hairlike processes on the 
cells at the termination of the nerve fibers of hearing. 
These fibers, forming the auditory or eighth cranial nerve, 
conduct the stimulus to the brain. 
The Care of the Ears. - Hard objects, such as pencils 
and sticks, should not be pushed into the external ear for 
fear of breaking the ear drum. The wax, which tends to 
keep insects and dirt from lodging on the tympanic mem- 
brane, sometimes collects in too large quantities in the 
canal. It may then be removed with the round end of a 
wire hairpin. Insects finding their way into the ear may 
be killed or made to come out by putting in a few drops 
of warm soapy water while the patient is in a reclining 
position, with the affected ear uppermost. In ten minutes 
the ear may be turned down on the pillow, when the water 
will flow out and carry the insect with it. 
Deafness. - The ear is a very delicate organ, and injury 
to any of its parts may result in deafness. A box on the 
ears may rupture the ear drum, but in many cases nature 
will mend this break. Closure of the Eustachian tube by 244 
THE SENSE ORGANS 
catarrh, so that the pressure of the air in the middle ear 
cannot be made equal with that outside, sometimes causes 
partial deafness. A growth of germs in the tympanum, 
producing an inflammation, as in running ears, may make 
the three little bones grow together solidly at their ends, 
and then they cannot move freely to transmit sound. More 
than half of the school children in the United States 
suffer from a defect in the ears, eyes, nose, or throat. 
The deaf and dumb are unable to hear because the 
sense organ in the cochlea is imperfect. Some cases of 
deafness resulting from disease or accident can be cured, 
but one should never pay attention to the numerous ad- 
vertisements in newspapers and magazines offering to 
cure deafness. They are the words of quack doctors who 
rob people of thousands of dollars and are likely to dam- 
age the ear seriously. An honest physician does not ad- 
vertise a sure cure for deafness, but does all in his power to 
enable his patients to recover their hearing. 
Questions 
1. Explain the nature of sense organs. 2. Name eight senses. 
3. Name the senses having organs located in the skin. 4. Of what 
use are the sense organs ? 5. Why do we not feel the particles of food 
brushing against the sides of the stomach? 6. Describe the sense 
organ of smell. 7. Explain the sense of taste. 8. Give the three 
parts of the organ of hearing. 9. Describe the middle ear. 
10. Name the three parts of the internal ear. 11. How is the fluid 
arranged in the internal ear ? 12. Of what use are the semicircular 
canals? 13. Explain the location and use of the cochlea. 14. De- 
scribe how sound is heard. 15. Give some points in reference to the 
care of the ears. 16. What may cause deafness ? 17. Why is it un- 
wise to patronize doctors who advertise to cure deafness ? 18. Test 
each ear by closing one with the finger and then listening to the tick 
of a watch in a distant part of the room. SUGGESTIONS FOB THE TEACHER 
245 
Suggestions for the Teacher 
1. Let the children test the sense of taste on different portions of 
the tongue by placing bits of sugar and salt on various regions of the 
tongue. 
2. Test the hearing of the pupils by placing a ticking watch at 
varying distances from them. Ask the pupils to note through which 
ear they hear the more distinctly. The test can be made by closing 
one of the ears with the finger. It is important that the teacher may 
discover any defects in the hearing among the children, as dullness and 
apparent stupidity are often due to some diseased condition of the ears 
which may in early life be corrected by a physician. The children 
who do not hear distinctly should always be given the front seats. 
3. The teacher may render a great service to any pupil partially 
deaf by talking the matter over with the parents and impressing upon 
them the danger of patronizing quack doctors, and the need of an 
immediate examination and advice by a physician. It is well to 
remember that in many cases partial deafness has resulted from 
adenoid growths described on page 147. XXII. THE SENSE ORGANS (Continued) 
THE EYE 
The Location of the Eye. - The dome-shaped cavities in 
the front of the skull and just below the region of the 
eyebrows are the orbital cavities, in which the eyeballs are 
lodged. Thick layers of fat within each cavity make 
a secure resting 
place for the eye- 
ball, which is held 
loosely by six mus- 
cles and the optic 
nerve. The optic, 
or second pair of 
cranial nerves, 
pass through holes 
in the skull to the 
brain and serve 
to convey the im- 
pressions made by 
light. 
How the Eyeball is Moved. - Four muscles attached to 
the upper, lower, outer, and inner surfaces of the ball are 
connected with the bones in the back part of the orbit. 
These are called recti muscles, because they are straight. 
A contraction of the inner one turns the ball toward the 
nose, while the outer one pulls in the opposite direction, 
Fig. 158. - Side of the orbital cavity cut out to 
show the muscles moving the eyeball, o, optic 
nerve ; a, muscle cut loose. 
246 THE WALLS OR COATS OF THE EYEBALL 
247 
and the upper and lower muscles turn the ball upward 
and downward respectively. Two oblique muscles give 
other motions to the ball. Cross eyes are caused by the 
inner recti muscles being stronger than the outer ones. 
The Parts of the Eye. - The complete eye consists of 
the eyebrows, which 
prevent the perspira- 
tion from running 
down into the eyeball, 
the eyelids, which 
protect the eyeball 
in front, and the eye- 
ball itself. The eyeball 
is nearly spherical, 
and consists of an 
outer wall one tenth 
of an inch thick filled 
with three transparent 
substances, called hu- 
mors. As the eye of 
a cow, pig, or cat has 
the same structure as 
a human eye, the dis- 
section or cutting apart 
of the eyeball of any one of these animals will be a 
great help to pupils in their study of the organ of sight. 
The Walls or Coats of the Eyeball.-The wall of the 
eyeball is composed of three coats. The outer coat consists 
of the tough and thick sclerotic part behind, and the trans- 
parent cornea in front. The middle coat, about as thick as 
paper, is formed largely of the black choroid portion, con- 
Fig. 159. - Horizontal section through the 
eye. a, aqueous humor; ac, fovea; b, 
blind spot; ci, fibers of ciliary muscle; co, 
cornea; ch, choroid coat; ir, iris; I, crys- 
tallinelens; n, ciliary processes; op, optic 
nerve; s, sclerotic coat. 248 
THE SENSE ORGANS 
tinuous in front with the iris appearing blue, gray, or 
brown according to the color of the eye. A circular 
opening in the center of the iris is the pupil, through 
which light passes to the interior (Fig. 159). By means 
of muscular fibers forming part of the iris the pupil is 
made to vary in size so as to regulate the amount of light 
reaching the inner coat of the eye. A bright light dimin- 
nishes the size of 
the pupil. The 
inner coat of the 
eyeball is the ret- 
ina. It is thinner 
than the paper of 
this book, very 
tender, and of a 
pinkish white color. 
It is made of connective tissue and nerve matter, and 
forms the end organ of the optic nerve. 
The Humors of the Eye. - The interior of the eyeball is 
divided into two chambers by the most solid humor, called 
the crystalline lens. The anterior chamber, between the 
cornea and lens, is filled with a watery fluid, known as 
the aqueous humor. The much larger posterior chamber is 
occupied by the vitreous humor, which appears like a 
colorless jelly. 
If the posterior half of the wall of a cow's eyeball, 
freshly secured, is cut away with the scissors and the ball 
then laid so that the cornea rests on fine print, the letters 
will appear greatly magnified. The crystalline lens, 
which is held in place by a delicate ligament attached 
where the cornea unites with the sclerotic coat, may be 
Fig. 160. - Diagram showing how the convex 
lens na brings the rays of sunlight to a focus 
at/. Note how the ray is bent at b and also at 
d, while the ray at n or a is not affected. THE NATURE OF LIGHT 
249 
removed and supported on a paper with a small hole and 
used temporarily for a magnifying glass. 
The Nature of Light. - Light is produced by the waves 
or vibrations of a substance called ether. It is present 
in all space, and even where air does not exist. The 
waves of ether aroused by the sun or lamp make impres- 
sions on the retina, 
which are trans- 
mitted to the brain 
by the fibers of 
the optic nerve. 
Many objects, such 
as a pencil or a 
table, have no 
power in them- 
selves to produce 
light, but they 
reflect or throw 
back the light 
waves started by 
the candle or sun. 
The waves of light are like the waves in water caused 
by tossing a stone into it, but they travel much faster. 
The rate of progress is about 186,000 miles per second. 
They travel in straight lines. Each of the millions of 
lines of light radiating from an object in all directions is 
called a ray. Substances like glass, which permit the 
rays of light to pass through them readily, are said to be 
transparent. A ray of light passing through a glass with 
curved surfaces may have its direction changed, as seen in 
the diagram. 
Fig. 161. - Diagram of the shape of the lens; A, 
when viewing far objects; B, when viewing 
near objects; a, ligament of the lens; e, attach- 
ment of ciliary muscle m which in B is con- 
tracted so as to draw forward the choroid coat 
at n and thus loosen the ligament of the lens. 250 
THE SENSE ORGANS 
The Bending of the Rays of Light. - A ray of light 
passing through glass whose surface it does not strike 
perpendicularly is bent out of its direct course. A piece 
of glass whose opposite surfaces curve outward forms a 
convex lens, while one with the opposite surfaces curving 
inward toward each 
other is a concave lens. 
Rays of light passing 
through a convex lens 
are made to converge 
so that all meet in one 
point called the focus, 
as shown in the figure. 
The Process of Seeing. 
- In order that the ret- 
ina may be stimulated 
in a way to give the 
brain a clear image of 
any object, the rays of 
light coming from the 
object must be made to 
meet at one point on the 
retina. To effect this, 
the crystalline lens is convex. Since the rays passing 
through the lens near its edge are bent more than those 
passing through near the center, it is necessary to have 
behind the crystalline lens another lens, the vitreous 
humor. This together with the aqueous humor so acts 
as to bring the rays to one point on the retina. 
The eyeballs are so held by the muscles that the rays 
of light coming from an object are focused on a corre- 
Fig. 162. - Diagram showing how near- 
sightedness as in B and farsightedness as 
ki A can be corrected by glasses. The 
dotted lines show how the rays of light 
are affected by the glasses, while the un- 
broken lines show the direction of the 
rays when the glasses are not present. NEARSIG HT EDNESS 
251 
spending area in each eye. This area, called the fovea, or 
point of acute vision, is a quarter of an inch to the outer 
side of where the optic nerve pierces the eyeball. After 
slightly rotating one eyeball by pushing on it with the 
finger, the rays of light will not strike the fovea in that 
eye, and consequently the object will appear double. 
The Power of Accommodation. - The change frequently 
taking place in some parts of the eye in order that it may 
see distinctly objects that are near by or those far off, is 
called accommodation. After reading several hours, the 
eyes grow tired, 
because a con- 
stant effort must 
be made to render 
more curved the 
convex surfaces 
of the crystalline lens. This greater bulging of the lens 
is necessary to bring the rays of light from a near-by 
object to a focus on the retina. The bulging is produced 
by contracting the ring of muscular fibers, the ciliary 
muscle, lying in the sclerotic coat at the edge of the cornea 
where the ligament of the lens is fastened. The con- 
traction of the ciliary muscle loosens the ligament which, 
when tight, tends to flatten somewhat the curved faces 
of the lens (Fig. 161). 
Nearsightedness. - This is usually due to the eye being 
longer than normal from before backward. The rays of 
light are brought to a focus before they reach the retina. 
Sometimes, however, the eye is of usual length, but the 
lens or cornea is too convex and therefore focuses the 
light before it reaches the retina. This defect is seldom 
Fig. 163. - Snellen's test letters. These should be 
seen distinctly by a correct eye at a distance of 
twenty feet. 252 
THE SENSE ORGANS 
present in children under four years of age. It is pro- 
duced in later years by pressure of the muscles on the 
sides of the eyeballs whose coats have become weak. 
Nearsightedness is remedied by wearing double concave 
glasses, which prevent the rays of light from coming to 
a focus too soon. 
Farsightedness. - This is caused either by the eye 
being shorter than normal from before backward or by 
Fig. 164. - To test for astigmatism. When looking with one eye at either 
figure, if some of the lines appear blurred, astigmatism is present. 
too little curvature of the surfaces of the lens. This is 
an exceedingly common ailment among persons over 
50 years of age. In young people the lens is soft, and 
therefore its shape is easily changed by tightening or 
relaxing the ligament enveloping it. The eye at rest has 
the lens so shaped as to focus the light from objects a 
hundred feet or more distant. Farsightedness is reme- 
died by the use of convex glasses. 
Astigmatism. - This is a serious defect in the eye, 
caused by the unequal curvature of the surface of the 
cornea or of the lens. That is, the curve of the line HOW TO KEEP THE EYES STRONG 
253 
passing across the center of the cornea from side to side is 
greater or less than the curve of a line extending up and 
down across the center of the cornea. Headache and the 
smarting of the eyes after continued use are signs of astig- 
matism. It may be remedied by glasses, which can be 
provided only by an oculist after the eyes have been 
carefully measured. 
Color Blindness. - One out of every 20 male persons is 
color blind, while only one out of every 200 females is 
similarly afflicted. Color blind people are in most cases 
able to distinguish all colors except red and green with 
their various shades. No one who is color blind can 
become a railway engineer or a pilot on a vessel. Its 
cause is unknown, and it cannot be cured. 
Tears. - The tears, composed of water and a very slight 
amount of salts, are continually formed by the lachrymal 
gland in the upper and outer part of the orbital cavity 
just within the rim of the orbit. It is about as large 
as a peanut seed. The tears, which are for the pur- 
pose of moistening the cornea and eyelids, are carried 
away by the tear duct. This leads from the inner corner 
of the eye through the bone into the nose. Certain 
emotions cause the tears to be formed so abundantly that 
they overflow and run down the cheek. 
How to keep the Eyes Strong. - Examination of the 
children in one of the large city schools showed that at 
six years of age four fifths of them had perfect eyes, and 
only four out of a hundred had serious defects in sight. 
At eight years of age three fourths of the children pos- 
sessed perfect eyes, and eight out of every hundred had 
some bad defect in the eye. At eleven years of age 254 
THE SENSE ORGANS 
eleven out of a hundred had some serious eye trouble, and 
only a little over two thirds had perfect eyes. These 
facts show that most people are born with good eyes, but 
they injure them 
by use in a wrong 
way. 
The book should 
never be held nearer 
to the eyes than one 
foot, and the read- 
ing of print finer 
than that used in 
this book should be 
avoided by young 
people. The fine 
print used as foot- 
notes and explana- 
tions of the main 
text in many text- 
books and even 
physiologies is re- 
sponsible for start- 
ing many eyes on 
the road to ruin. 
Trying to see in a dim light and leaning the head forward 
while reading cause pressure on the eyeball and produce 
nearsightedness. While using the eyes, the head should 
be held erect and the light be so arranged as not to 
come from in front. The aching or smarting of the 
eyes, pain in the head or back of the neck, frowning, 
or dizziness indicate that the eyes are not in perfect 
Fig. 165. - Portrait showing how the eyes may 
be injured. THE COMMON INJURIES TO THE EYE 
255 
working order. Out of 58,948 children whose eyes were 
tested in New York, 17,928 were suffering from defective 
vision. 
No person should use glasses until discomfort is experi- 
enced after using the eyes one or two hours in reading 
print as coarse and clear as that in this book. In seeking a 
remedy for poor sight, one should consult a physician and 
not take the risk of having the eyes permanently injured 
by purchasing glasses from a quack doctor. Quacks may 
be known by the 
large advertise- 
ments they insert 
in newspapers or 
magazines. 
The Common 
Injuries to the 
Eye. - Cinders 
and bits of other 
hard substances 
often get beneath the lids of the eye. They irritate 
the delicate transparent membrane lining the lids of the 
eye and passing over the cornea. By having the patient 
look downward one may seize the edge of the upper lid 
and turn it backward over a rounded match stick. The 
particle of matter can then be removed with a corner of 
a clean handkerchief or a bit of absorbent cotton wound 
around the head of a pin. The lower lid may be merely 
drawn down to see and clean off the surface. 
When the eyes are red or inflamed from any cause, 
some relief may be had by bathing them several times 
daily with a solution of boracic acid, made by dissolving 
Fig. 1(56. - Method of turning the eyelid up to 
remove dirt. 256 
THE SENSE ORGANS 
in a teacupful of water as much boracic acid as will lie on 
a silver half dollar. 
Sore eyes are usually much relieved by being washed out 
with the boracic acid solution, because this tends to kill 
the germs causing the trouble. Care should be taken 
that the germs in the sore eyes do not get on pencils, 
towels, or handkerchiefs used by other persons and thus 
make their eyes sick. 
Cataract is a serious affection which may produce com- 
plete blindness. It is due to the crystalline lens becom- 
ing opaque. The removal of the lens and the use of 
proper glasses often remedy the difficulty. 
How Narcotics Affect the Sense Organs. - The use of 
tobacco daily seems in some degree to affect the sense 
organs of the mouth so as to lead to a desire for strong 
drink. Much chewing and smoking tend to lessen the 
sense of taste. Hearing, as a rule, is but little injured by 
either tobacco or alcohol, though occasionally a catarrh ex- 
tending up the Eustachian tube to the middle ear may be 
made more severe in the young by the use of cigarettes. 
Excessive smoking is likely to decrease the keenness of 
the sense of smell, because the delicate mucous membrane 
containing the olfactory organs is irritated by tobacco 
smoke. 
It has been reported that the excessive use of tobacco 
causes wasting of the optic nerve leading from the eye to 
the brain. Late investigations, however, show that this 
is probably not true. Nevertheless frequent smoking in 
the young has been known to affect the sight seriously. 
Dr. Alfred Woodhull, of the United States Army, says : 
" Tobacco is liable to render vision weak and uncertain, 257 
QU ESTIONS 
causing objects to appear nebulous, or it creates the sensa- 
tions of floating spots." One well-known eye specialist 
alone reports 35 cases of injured vision produced by the con- 
tinual irritation of the optic nerve by tobacco. Dr. Mc- 
Sherry says when sight fails in smokers and no change in 
structure can be seen, tobacco poisoning may be assumed. 
Candidates for the United States Naval Academy rejected 
on account of poor eyesight have in most cases admitted 
using tobacco while young. 
The period of life before twenty is the time when the 
sense organs are most markedly affected by the unwise 
use of tobacco and alcoholic drinks. Even later in life, 
narcotics may do lasting injury to the senses. The use 
of much liquor produces bloodshot eyes, because the 
muscles of the walls of the arteries are relaxed and so 
become enlarged. Long use of intoxicants has been 
known to do permanent injury to the optic nerve, which 
was probably due to the paralyzing effect of the alcohol 
on the nerves controlling the blood vessels of the head. 
Questions 
1. Explain the location and attachments of the eyeball. 2. How 
is the eyeball moved ? 3. Name the parts of the eye. 4. Name the 
parts composing the three coats of the eyeball. 5. Describe the 
retina. 6. What is the color of your iris and what is its use? 
7. Name the three humors. 8. Explain the nature of light. 9. By 
means of a drawing show how the rays of light are bent in passing 
through a lens. 10. Describe the process of seeing. 11. What de- 
fects in the eye cause near sight? 12. How may near sight and 
tar sight be remedied? 13. What is color blindness? 14. Explain 
the formation of tears. 15. Give facts showing that the eyes are 
more perfect in children than in older ones. 16. What may help 
keep the eyes in good condition ? 17. How may particles of dirt be 
DAV. PHYS 17 258 
THE SENSE ORGANS 
removed from beneath the eyelids? 18. What care should be given 
sore eyes? 19. What effect has tobacco on the sense organs? 20. At 
what period of life are narcotics liable to do most injury to the sense 
organs ? 
Suggestions for the Teacher 
1. Several eyes of pigs or cows may be secured from the butcher. 
Note the attachment of the several muscles to the tough sclerotic 
coat. In very cold weather one or two eyes should be left out over 
night to freeze, or they may be frozen in a few hours in a mixture of 
cracked ice and salt. With a sharp knife cut one of the frozen eyes 
through the middle from before backward, and note the arrangement 
of the three humors and coats, and then place the eye in a dish of 
pure formaldehyde solution. A fresh eye should be cut open from 
side to side with a pair of sharp-pointed scissors. Keep the point of 
the blade near to the inner surface of the eyeball. The vitreous 
humor and lens may be turned out together, and when laid on tine 
print, will show considerable magnifying power. The retina appears 
as a thin, grayish, very tender lining of most of the eyeball. Note the 
black choroid as thin as paper. 
2. Show with a magnifying glass or convex lens of any kind how 
the rays of light are brought to a focus by holding the glass in the 
sun at the right distance from a piece of paper to show a spot of light 
as large as a pin's head on the paper. 
3. Test the eyes of the pupils with Snellen's test letters, and note 
how close the pupils hold the book to the eyes when studying. Re- 
port any defects to the parents and advise that an oculist be consulted. 
Insist that the pupils maintain the right position in reading to avoid 
injuring the eyes. It is far more important that the pupil should 
nave perfect eyes and ears than that he should learn his lessons. XXIII. THE CAUSE OF DISEASE 
The Work of Parasites. - Only one in every forty per- 
sons dies of old age. About twice that number meet 
death by accidents, while disease is responsible for over 
nine tenths of the mortality of the human race. The 
numerous diseases 
affecting man may be 
divided into two classes, 
known as infectious and 
non-infectious. 
The infectious dis- 
eases are caused by 
tiny plants or animals, 
called parasites, feed- 
ing upon the human 
body which is their 
host. These parasites, 
the smaller of which 
are commonly called 
microbes or germs, make one ill chiefly by means of their 
poisonous excretions. In Europe and America 60,000,000 
people are annually laid prostrate by infectious diseases 
which result in over 3,000,000 deaths. 
Kinds of Diseases. - Such infectious ailments as con- 
sumption, smallpox, and scarlet fever which may be con- 
tracted by breathing in the germs floating in the air are 
Fig. 167.-Germs that cause lockjaw. 
Photographed through the microscope. 
259 260 
THE CAUSE OF DISEASE 
called contagious diseases, because the healthy acquire the 
disease by coming near where the sick are or have been. 
Maladies like yellow 
fever, lockjaw, and ma- 
laria belong to the 
group of non-contagious 
diseases for the reason 
that persons living in 
the same house and even 
sleeping in the same bed 
with the sick do not 
become ill unless a 
mosquito or a sharp 
instrument conveys the 
germs from the sick to 
the well. 
The non-infectious diseases such as alcoholism, diabetes, 
insanity, and cancer are due to changed methods of work 
and growth on the part of cells in certain regions of the 
body. More people die 
from infectious diseases 
than from non-infec- 
tious. This means that 
most ill health results 
from tiny forms of life 
growing within our 
bodies. 
The Discovery of 
what causes Disease. - 
Several hundred years ago disease was thought to be due to 
evil spirits which took up their abode in the body. Ilere 
Fig. 168. -Louis Pasteur. 
Fig. 169. - Glass slip g, to which the lower 
lip was touched at a-e as one would 
touch a cup in drinking. A fourth part 
of the circle n was photographed through 
the microscope, giving the picture as 
seen in Figure 170. THE DISCOVERY OF WHAT CAUSES DISEASE 
261 
they produced con- 
tinuous suffering until 
driven out by various 
devices such as beat- 
ing the patient with a 
strap or giving him 
so-called medicine 
consisting of pow- 
dered human bones. 
Although for fifty years 
it has been thought 
by some that many 
diseases were due to 
bacteria, yet the fact 
that each of certain diseases is caused by a particular bac- 
terium was not clearly proved until 1876. In that year 
Louis Pasteur, of France, showed that anthrax, a sickness 
of cattle, was caused 
by a rodlike plant. 
He secured a few 
of these plants from 
the blood of a sick 
cow, and planted them 
in broth, where they 
increased rapidly in 
number. A few were 
then injected under 
the skin of a healthy 
cow which soon after 
became sick. In her 
blood the same plants 
Fig. 170.-Numerous epithelial cells from 
the mouth left on the glass as described 
in Figure 169. 
Fig. 171. - One of the cells like those shown 
in Figure 170 left by the lip on the glass. 
The 200 or more black bodies are bacteria. 262 
THE CAUSE OF DISEASE 
were found in vast numbers. Dozens of similar experi- 
ments and the presence of these particulai- plants and no 
others in the blood 
of all animals with 
anthrax have made it 
certain that the disease 
is caused by this special 
germ. In a similar 
manner or by some 
other equally reliable 
method it has been shown that each of the following ail- 
ments is produced by its own particular kind of germ: 
diphtheria, typhoid fever, malaria, pneumonia, leprosy, 
lockjaw, hydrophobia, influenza, or grippe, erysipelas, 
and tuberculosis. 
There is no doubt 
that measles, scarlet 
fever, smallpox, and 
mumps are also pro- 
duced by germs, but 
no one has yet been 
able to find them. 
Inasmuch as all infec- 
tious diseases may be 
prevented by keeping 
the germs out of the 
body, much effort has 
been made to learn how 
they gain entrance. 
How Germs enter the Body. - The germs of any conta- 
gious disease may be taken in by breathing, but other 
Fig. 172. - Spot a, on a glass slide g, 
touched with the thumb moistened from 
the lips as in turning the pages of a book. 
Fig. 173. - The fourth part of the circle in 
Figure 172, showing a score of cells from 
the lips. Photographed through the 
microscope. HOW GERMS ENTER THE BODY 
263 
channels of infection 
are also known. In- 
fluenza, or grippe, 
pneumonia, diphtheria, 
sore throat, and whoop- 
ing cough are no doubt 
often contracted by a 
healthy person drink- 
ing from the same cup 
lately used by those 
just recovering from 
sickness. Numerous 
disease germs as well 
as harmless ones are 
present in the sputum 
of such patients. By 
examining with the microscope a glass touched by the lips, 
I have found over 20,000 bacteria. I have seen more than 
5000 germs deposited on a glass slip by a single touch of 
a finger moistened with saliva 
to aid in turning the pages 
of a book. The fingers touch- 
ing soiled books, clothing, 
pencils, or other things han- 
dled by the sick may convey 
the germs to the mouth. The 
number of days elapsing from 
the time the germs enter the 
body to the time when the 
disease appears is known as 
the incubation period. 
Fig. 174. - One of the cells like those left by 
the thumb on the glass slide, as shown in 
Figure 173. The hundred or more tiny 
black bodies are bacteria, always abun- 
dant on the lips. Photographed through 
the microscope. 
Fig. 175. - Two flies feeding on 
spit containing millions of bac- 
teria, many of which will be 
carried on their feet to the food 
on the table. 264 
THE CAUSE OE DISEASE 
The Character and Incubation Period of Infectious Diseases 
Lockjaw 
Yellow fever 
Hydrophobia 
Malaria 
Sleeping sickness 
Blood poisoning 
Dysentery 
Peritonitis 
Appendicitis 
Trichinosis 
Non-contagious 
Period of 
Incubation 
in Days 
Diphtheria .... 1-6 
Tuberculosis 20-10,000 
Typhoid fever 8-20 
Leprosy unknown 
Pneumonia unknown 
Grippe 1-5 
Cholera 1-10 
Bubonic plague .... 3-12 
Contagious 
Scarlet fever 1-7 
Smallpox 8-16 
Measles 8-16 
Mumps 14-21 
Chicken pox 12-16 
Whooping cough .... 8-16 
Certain colds 6-12 
Very contagious 
How the Germs of Tuberculosis enter the Body. - Tubercu- 
losis, commonly called consumption, the most common of all 
maladies, is generally acquired by breathing into the lungs 
the germs which come from the dried sputum of persons 
having the disease. It has lately been shown that the germs 
may also reach the lungs by passing through the walls of the 
alimentary canal into the lymph vessels and thence by the THE DANGER FROM TUBERCULOSIS IN COWS 
265 
blood to the lungs. Here the thin-walled capillaries per- 
mit the germs to pass through into the tissues. The 
germs once in the body may lie there without growing 
for twenty years. 
The lungs of ten healthy guinea pigs fed on milk con- 
taining tubercle bacilli became in about two months badly 
affected with tuber- 
culosis. These 
germs, injected 
under the skin of 
hogs or cows, in 
most cases produce 
disease of the lungs. 
Calves fed on the 
milk of tuberculous 
cows only a few 
days acquire tuber- 
culosis of the lungs. 
The sputum of tu- 
berculous patients 
contains millions of 
the disease germs. 
These may get on 
the furniture, may 
be carried by flies 
from the spittoon to food, or may dry and be blown 
about in the wind. In any case they are liable to reach 
the mouth of a healthy person. 
The Danger from Tuberculosis in Cows. - A large number 
of cows have tuberculosis, but it is often not detected by a 
farmer until the animals become very sick. Nearly one 
Fig. 176. - A dish of beef broth jelly on which 
a fly was allowed to walk for a few minutes. 
Wherever a germ was rubbed off from the 
fly's feet, it grew and made millions of germs, 
appearing as a white spot the next day. The 
white spots in the picture therefore show how 
many germs that fly would have left on food 
over which it crawled. 266 
THE CAUSE OF DISEASE 
third of the cattle of Great Britain are said to be tuber- 
culous, and investigations show that there are not less 
than a quarter of a million tuberculous cows east of the 
Mississippi River. Fortunately less than half of them 
shed the germs in their milk, but vast numbers of the 
germs are found in their manure. This often soils the 
Fig. 177. - Showing how disease germs often reach the drinking water, c, 
cesspool; Im, layer of rock; w, wash water. 
cow, then becomes dry, and is later brushed off into 
the milk pail. 
Germs of tuberculosis have been frequently found in 
milk, and numerous cases are on record where the use of 
milk from sick cows has given the disease to children. 
Tuberculosis germs lodging in the lungs produce con- 
sumption or phthisis; in the lymphatic glands, scrofula ; 
in the skin, lupus; in the bone, white swelling, hip-joint 
disease, or other trouble; and in the membranes of the 
spinal cord or brain, meningitis. TYPHOID FEVER AND WATER 
267 
Typhoid Fever and Water - The germs of typhoid fever 
gain access to the body in most cases with food or water. 
In 200 epidemics, during each of which from 10 to 1300 
people were affected with the fever, 71 per cent were 
caused by water and 28 per cent by milk. In the winter 
of 1885 the excreta from a 
typhoid patient were cast out 
on the snow along the moun- 
tain stream supplying Plym- 
outh, Pennsylvania, with 
water. During the first thaw 
of spring, the excreta were 
carried with the melted snow 
into the reservoir, and two 
weeks later numerous cases of 
fever appeared daily in the town 
until there was a total of 1104 
persons sick. When an in- 
vestigation showed that none 
who had used water from 
other sources than the mountain 
stream were affected with the 
fever, there was no doubt about 
the cause of the epidemic. Other serious epidemics have 
occurred through the use of polluted water as follows : in 
1893-1894 Windsor, Vermont had 130 cases, Grand Forks, 
North Dakota had 1245 cases, and Montclair, New Jersey 
had 108 cases; in 1895 Stamford, Connecticut had 406 
cases ; in 1903-1904 Leadville, Colorado had 450 cases, 
Marshaltown, Iowa had 418 cases, Butler, Pennsylvania 
had 1364 cases, and Watertown, New York had 600 cases. 
Fig. 178. - Drawing of a piece 
of deltoid muscle of a girl 
who ate pork not well cooked, 
and died of trichinosis. Note 
the many-coiled trichina. 
Magnified. 268 
THE CAUSE OK DISEASE 
The scattered cases of typhoid occurring in nearly ah 
communities may be due to a very slight pollution of the 
water, to flies carrying the germs from human excreta to 
food, or to eating raw oysters, lettuce, and celery, in or 
upon which the germs may lodge. 
Typhoid Fever transmitted by Milk. - Many severe epi- 
demics of fever have resulted from infected milk. As 
the cows never suffer 
from this malady, it is 
evident that the germs 
must get into the milk 
from an outside source. 
This source is often 
the water used from a 
polluted well or stream 
to wash the cans. A 
single germ remaining 
in the water, clinging 
to the can, is capable of 
developing so rapidly 
in milk as to give rise 
to over 1,000,000 germs in 12 hours. Frequently germs 
have been known to get into the milk from the hands or 
clothes of those who have just recovered from the disease, 
or from those who have been nursing a typhoid patient. 
Infectious but not Contagious Diseases. - The germs of 
lockjaw live in the soil and get into a wound with dirt. 
Hydrophobia is caused by the bite of rabid cats or dogs 
with the germs of this disease in their saliva. Trichina 
are tiny worms sometimes found in pork, which if not well 
cooked may cause sickness. Yellow fever and malaria are 
Fig. 179. - Two malarial germs, each in a 
blood corpuscle. Magnified. ALCOHOL AND DISEASE 
269 
caused by germs put into the blood by the bite of mos- 
quitoes. Only one kind can transmit the yellow fever. 
The few kinds of mosquitoes bearing malaria germs can 
be recognized by their oblique position in standing. 
The Hookworm Disease. - 
This is common among the 
people of the South. It is 
caused by tiny worms suck- 
ing blood from the lining of 
the intestine and giving off 
poison. This makes the per- 
son feel weak and lazy, and 
may cause death. The eggs 
of the worms pass out with 
the bowel excretions and hatch 
into tiny young which may 
crawl to the well or spring 
and so reach another person. 
They often spread through the 
soil and enter the body by bor- 
ing through the skin of those 
going barefooted, causing " dew 
itch" or "ground itch." 
Alcohol and Disease. - The 
continual use of liquor weakens 
the cells of the body which 
naturally kill off the harmful germs. Late investigations 
clearly show that those consuming alcoholic drinks, except 
in very small quantities, are not only attacked sooner than 
others by infectious diseases, but are also less able to resist 
the effects of the disease. The greatest Kussian scientist 
Fig. 180. - Position taken by a 
common mosquito (Culex) a, 
and by a malaria mosquito 
(Anopheles) b, when alighting. 
Note that in the malaria mos- 
quito the two palpi just below 
the sucking bill are about 
four times as long as in the 
common mosquito. After 
Howard. 270 
THE CAUSE OF DISEASE 
has lately said that alcohol paralyzes those elements in the 
body tending to prevent disease. By experimenting he 
found that in exposing rabbits to certain disease germs 
only those animals which had been given alcohol ever 
contracted the 
disease. 
Constant users 
of alcoholic drinks 
are especially lia- 
ble to fall a prey 
to diseases of the 
respiratory sys- 
tem. Alcohol so 
weakens the body 
cells which ordi- 
narily destroy the 
germs of pneu- 
monia that the 
disease is often 
able to gain a 
hold in the sys- 
tems of drinkers. 
The enlargement 
of the blood vessels of the lungs produced by the stupe- 
fying effect of the alcohol increases the tendency to 
inflammation. 
Indulgence in the use of beer, wine, and whisky is con- 
sidered to have such a serious effect on the tissues of the 
body that The International Congress of Tuberculosis in 
1905 passed the following resolution : " In view of the 
close connection between alcoholism and tuberculosis, this 
Fig. 181.-Well, to, containing very impure water 
causing intestinal sickness. Analysis of the 
water showed many germs indicating that it was 
dangerous for use. SUGGESTIONS FOR THE TEACHER 
271 
Congress emphasizes the importance of combining the 
fight against tuberculosis with the struggle against alco- 
holism." 
Diseases of the liver, kidneys, blood vessels, and heart 
often result from the long-continued use of beer or 
whisky. . 
Questions 
1. Of every hundred deaths how many result from disease? 
2. What is the cause of infectious diseases ? 3. Give facts showing 
that infectious diseases result in much sickness. 4. What is a conta- 
gious disease? 5. Name some contagious diseases. 6. Name some 
infectious diseases not contagious. 7. How has it been shown that a 
special germ causes a special disease ? 8. Name ten diseases caused by 
germs. 9. How may diphtheria, sore throat, whooping cough, and 
grippe be contracted ? 10. How may the germs of some diseases be 
transferred to the leaves of a book? 11. Explain the incubation period 
of disease. 12. Name three diseases with short incubation periods. 
13. Name two diseaseswith long incubation periods. 14. Name four 
very contagious diseases. 15. How do the germs of tuberculosis enter 
the body? 16. What facts show that the germs of tuberculosis get- 
ting into the blood are most likely to lodge in the lungs? 17. How 
do germs of tuberculosis get into milk ? 18. What diseases are 
caused by the germs of tuberculosis? 19. How do the germs of 
typhoid fever enter the body? 20. Give facts showing that typhoid 
fever is generally acquired by drinking impure water. 21. How 
may flies be the means of causing typhoid fever ? 22. How is it pos- 
sible for milk to be the source of typhoid fever? 23. What cause 
lockjaw and hydrophobia? 21. IIow do the germs of malaria enter 
the system ? 25. Give evidence showing that alcohol is a factor in 
producing disease. 
Suggestions for the Teacher 
Bulletins or pamphlets published by the State Board of Health 
should be distributed among the pupils and each one asked to write 
on one or two sheets of paper what he considers the most important 
things to be remembered in the bulletins. These bulletins may be had 
free in most states by requesting them from the State Board of Health 
at the capital of the state. XXIV. THE PREVENTION OF DISEASE 
The General Methods. -There are three general methods 
of preventing infectious disease. One way is to destroy 
the harmful germs continually passing out of the sick 
body with the excretions, and so prevent them from reach- 
ing the healthy. A second plan is to stop the disease 
germs scattered about by careless people from entering the 
body. A third 
means of keeping 
away disease is to 
develop in the body 
tissues a substance 
which has the 
power to destroy 
certain disease 
germs entering the 
system. 
Destroying the 
Cause of Disease. 
- Until 1890 but little attention was given to the 
scientific prevention of disease. A sure method of re- 
straining criminals from robbing and killing, is to keep 
them shut up in prisons or to kill them. Likewise, a 
certain method of preventing harmful germs from robbing 
some citizens of health and killing others is to destroy 
the germs when they escape from the body of the sick. 
Fig. 182.-Diagram of a part of our nation's 
cemetery. The black dots represent the num- 
ber of graves made daily for persons dying of 
the four diseases. 
272 DESTROYING THE CAUSE OF DISEASE 
273 
The bowel and kidney excretions of a person suffering 
from any of the contagious diseases should always be 
treated in a way to kill the germs. This may be done by 
adding to them four times the quantity of boiling water. 
The easiest and surest method of killing the germs is to 
add to the excretions an equal amount of formalin, made 
by mixing a teacupful of formaldehyde solution with a 
gallon of water. After adding the 
germ killers, called disinfectants, 
the material should stand a half 
hour before being disposed of in 
the usual way. 
Nearly 300,000 cases of typhoid 
fever occur annually in this coun- 
try, resulting in about 40,000 
deaths. Careful investigations 
have shown that three fourths of 
this suffering and loss of life was 
due to negligence in permitting 
the living typhoid germs in the 
kidney and bowel excreta of the sick to escape into the 
streams, wells, and soil. The soil about many homes and 
schools in the South contains thousands of hookworms 
hatched from the eggs in the bowel waste allowed to touch 
the ground. These worms will pierce the skin of bare 
footed children and travel through the blood, lungs, and 
windpipe to suck the blood in the intestine. Where there 
is no sewer connection, tight tubs or cement tanks should 
be used for the body waste. It is wise to avoid going 
barefooted. 
It should be remembered that the disease germs often 
Fig. 183.'- A receptacle 
frequently receiving the 
germs of grippe, tuber- 
culosis, tonsilitis, and 
diphtheria to be distrib- 
uted by flies. 
DAV. PHYS. 18 THE PREVENTION OF DISEASE 
274 
continue in the excretions of the sick a week or more 
after recovery. Failure to kill the germs in the ex- 
creta of a single patient at Plymouth, Pennsylvania, 
resulted in 1104 cases of typhoid fever and many deaths. 
The sputum from the sick should be received on pieces of 
cloth or in well-greased pasteboard boxes covered to pre- 
vent the entrance of flies. The cloths or boxes should be 
burned at the end of each day. Flies are known to 
distribute the bacteria of consumption and typhoid 
fever. 
The Isolation of the Sick. - A person suffering from a 
contagious disease should in most cases be quarantined. 
To quarantine means to isolate or to separate the sick 
from the well. The patient should be placed in a large 
airy room shut off from the rest of the house as much as 
possible and exposed to the sun, nature's germ killer. 
The hangings and carpets and all unnecessary furniture 
should be removed. Only the nurse and doctor are to be 
allowed to enter the room, and no clothing, dishes, or 
other articles should be taken from the room without 
being soaked in boiling water. 
Disinfection of the Room. - Disinfection means the kill- 
ing of the agents producing disease. An antiseptic is a 
substance which merely restrains the germs from growing. 
Ice, vaseline, a one-per-cent solution of carbolic acid, and 
a weak solution of boracic acid are common antiseptics. 
The three best disinfectants are a five-per-cent solution of 
carbolic acid, sunlight, and formaldehyde solution. 
During the patient's sickness the room should not be 
swept, but wiped up daily with a cloth wrung out of a 
quart of water to which have been added two or three DISINFECTION OF THE PERSON 
275 
tablespoonfuls of formaldehyde solution. When the pa- 
tient has recovered, the room should be disinfected by 
closing it tightly, inserting wet paper in cracks and key- 
holes, and evaporating, by heating on an oil stove, two 
quarts of water to which has been added a pint of pure 
formaldehyde solution. In the absence of a stove the 
liquid maybe sprinkled 
on the floor and bed- 
ding, but the results 
are not so good. The 
room should remain 
closed twelve hours, 
and then be exposed 
to sunshine and fresh 
air a day or two. 
Disinfection of the 
Person.-After touch- 
ing a patient or han- 
dling his clothing, the 
hands should be thor- 
oughly washed with 
soap and water. The 
clothing used about the 
sick must be boiled 
before it is safe. Toys handled by a scarlet fever patient 
have been known to give the disease to others more 
than a year later. When the patient has recovered, 
his entire body, including the hair, should be carefully 
washed with water and plenty of soap. The outer 
clothes of the nurse should also be boiled, and in the 
more contagious diseases the hair thoroughly washed. 
Fig. 184. - Why a sick room should not be 
swept. A dish of beef broth jelly was 
left open for two minute in a room that 
was being swept. Wherever a germ fell 
it grew an .1 produced millions forming a 
white spot. Therefore the white spots 
show how many germs fell on a circle two 
inches in diameter. 276 
THE PREVENTION OF DISEASE 
Keeping the Germs out of the Body. - With great care 
it is possible to keep out of the body the agents causing 
at least five of the infectious diseases. The germs re- 
sponsible for diarrhea, dysentery, cholera infantum, and 
typhoid fever may generally be avoided by keeping flies 
away from food, and 
by drinking from clean 
vessels water or milk 
known to be pure, or 
by heating these fluids 
up to the boiling point. 
It is better to pas- 
teurize the milk, as 
described in Chapter 
VII. The use of 
boiled drinking water 
in Philadelphia, Cin- 
cinnati, Cleveland, 
Louisville, Memphis, 
New Orleans, St. 
Louis, and Washing- 
ton during the years 
1900-1904 would have prevented 50,000 cases of typhoid 
fever. The use of boiled water in Pittsburg during the 
same five years would have prevented 10,000 cases of 
fever in that city. 
The germs of malaria and yellow fever are easily ex- 
cluded from the system by preventing the two kinds of 
mosquitoes carrying them from biting. As the young of 
these insects live only in quiet pools of water with no fish, 
their numbers may be much lessened by draining the 
Fig 185. - Wigglers, the young of mosqui- 
toes, trying to breathe through their air 
tubes sticking out on the surface of the 
water covered with oil. KEEPING THE GERMS OUT OF THE BODY 
277 
puddles and pouring out the water in tubs and old cans. 
Where this cannot be done the young may be killed by 
kerosene poured on the tVater, using one pint for every 
hundred square feet of surface. 
Fig. 186. - Diagram showing how supplying a city with good water lessens 
the sickness and death. The lines b above each city show the relative num- 
ber of persons dying of typhoid fever before the water was filtered. The 
lines a show the number dying of typhoid after the water was filtered. The 
figures are the number of typhoid deaths occurring annually out of every 
100,000 inhabitants. 
The terrible bubonic plague, or black death, is also con- 
veyed to man by the bite of a flea living on rats and 
man. Leprosy may be transmitted by the bite of bedbugs 
or fleas. 
When near patients with severe colds, scarlet fever, 
smallpox, grippe, measles, mumps, and chicken pox there 278 
THE PREVENTION OE DISEASE 
is no way of shutting the germs out of the system, 
beeause they beeome mingled with the air. The germs 
of diphtheria and tuberculosis' are also likely to mingle 
with the air and enter the body of the healthy unless the 
patients use great care. The secretions of the mouth 
and nose should always be received into a cloth or special 
pasteboard cup and burned, and a cloth, to be later burned, 
should be held over the mouth while coughing. In quiet 
breathing no germs of any kind are given off. 
Importance of Filtered Water. - Many cities getting 
their water from streams likely to contain disease germs 
pass the water through a layer of sand and coarse gravel 
to remove the germs. Most sand filters remove about 
ninety-eight per cent of the germs in the water. The 
small house filters, made of specially prepared material, 
take out all germs, but must be cleaned daily and boiled 
weekly to be effective. 
Table showing the Saving of Life at Albany by Use of 
Filtration compared with Troy where during the Same 
Period the Water was not Filtered 
Death rate per 
100,000 in Albany, N.Y. 
Before filtration 
1894-1898 
After filtration 
1900-1904 
Typhoid fever .... 
104 
26 
Diarrheal diseases . . . 
125 
53 
Children under 5 yrs. . . 
606 
309 
Death rate per 
Water not filtered 
Water not filtered 
100,000 in Troy, N.Y. 
1S94-1898 
1900-1904 
Typhoid fever .... 
57 
57 
Diarrheal diseases . . . 
116 
102 
Children under 5 yrs. 
531 
435 THE POWER OF THE TISSUES TO KILL GERMS 
279 
Since the city filter ha been in use at Albany, New York, 
only one fourth as many deaths occur from typhoid fever 
as previously, and less than half as many deaths from 
diarrheal diseases. 
Sewage Disposal. - The liquid waste resulting from 
nousekeeping or manufacturing processes is named sew- 
age. This should 
never be permitted 
to run direct into a 
stream because of the 
germs and poisons it 
may contain. Such 
germs as those of ty- 
phoid fever have been 
known to cause dozens 
of cases of sickness and 
death after being car- 
ried a week in the water. 
The sewage should be 
passed through a 
storage tank and 
oxidizing filter. 
In the country or village, or when camping, gal- 
vanized iron cans should be used for the excretions 
from the body. A pint of dry earth thrown into the 
can daily will prevent odor and help change the waste 
matter to mineral earth. When the can is full the 
contents should be buried in a shallow hole in the 
garden or field. 
The Power of the Tissues to kill Germs. - There is no 
doubt that disease germs get into the mouth and nose 
Fig. 187. - The germs causing pneumonia 
are the small oval bacteria usually in 
pairs. Photographed through the micro- 
scope magnifying 1000 diameters. 280 
THE PREVENTION OF DISEASE 
every day. The bacteria causing sore throat and pneu- 
monia have been frequently found in the mouth and 
throat of healthy people. These germs can provoke 
disease only when one becomes chilled so that his body 
cells are weakened and permit the intruders to get a start. 
In health the nasal mucus, gastric juice, and other se- 
cretions destroy thousands of germs daily. The body 
Fig. 188. - A healthful bedchamber for clear summer nights whereby the 
germ-killing power of the blood may be greatly increased. 
cells manufacture and turn into the blood and other se- 
cretions of the body a substance capable of dissolving bac- 
teria. There are also other agents in the blood called 
opsonins which affect the bacteria so that the white blood 
corpuscles are able to swallow them. This power of the 
blood and other secretions to kill germs varies in dif- 
ferent persons, and also may be greater at one time than 
another in the same person. In adults this power to 
destroy the germs of scarlet fever and diphtheria is so HOW THE BODY BECOMES SAFE 
281 
great that healthy persons over 30 years of age seldom 
take these diseases. 
Alcohol and the White Blood Corpuscles. - It has for 
a long time been known that habitual drinkers when 
exposed to a contagious disease are much more likely to 
become ill than the total abstainers. The reason for this 
was not clearly under- 
stood until 1906, when 
it was found that the 
white blood corpuscles, 
which destroy disease 
germs, are stupefied 
by alcohol and thus 
prevented from doing 
their work. 
How the Body be- 
comes Safe from Some 
Diseases. - In case 
disease germs reaching 
an individual have no 
effect on him, he is 
said to be immune to that disease. This immunity, or 
safety, depends upon the germ-killing power of the 
body fluids. This power may be developed in two 
different ways, one of which is known as the natural 
method, while the other is the artificial method. The 
natural method consists in the use of an abundance of 
nutritious food well chewed, plenty of sleep, fresh air 
night and day, and an hour of daily exercise. This is 
the most successful method of preventing tuberculosis 
and colds. The artificial method is by the use of anti- 
Fig. 189. - Germs of tuberculosis from the 
spit of a consumptive. Photographed 
through the microscope. 282 
THE PREVENTION OF DISEASE 
toxins and vaccines secured from the domestic animals. 
Diphtheria, smallpox, lockjaw, and hydrophobia may 
always be prevented by this method if used in time. 
Tuberculosis. - The tiny plants causing this disease are 
so abundant everywhere that it is impossible for those 
living in towns and cities to keep them out of the system. 
More than half of the people over 25 years of age have at 
some time had growing in their tissues the bacillus tuber- 
culosis. The examination of a large number of bodies after 
death showed that 96 per cent of those between the ages of 
18 and 30 had been infected with the germs ; 50 per cent of 
those between the ages of 14 and 18 ; 33 per cent of those 
between the ages of 5 and 14 ; and 17 per cent of those be- 
tween the ages of 1 and 5 years. In most of these persons, 
the germs had not multiplied sufficiently to cause any dis- 
comfort, because the germ-killing power of the body fluids 
had kept them in check. The fact that 400 people are 
dying daily in the United States from this one disease 
and that one third of all deaths occurring between the 
ages of 15 and 45 years result from tuberculosis shows 
the importance of trying to render the body immune. 
Making the Body Safe from Tuberculosis. - Proper 
living will in 99 per cent of all well persons render the 
body capable of killing the germs of tuberculosis. The 
living or working rooms should be well ventilated, and 
the area of the open windows in the bedroom occupied by 
two should not be less than ten square feet in winter and 
twice as large in summer. Good food, including plenty 
of milk and eggs, should be taken. Exercise, especially 
such as calls into action the chest muscles and fills the 
lungs full of air, ought to be indulged in a half hour or MAKING THE BODY SAFE FROM TUBERCULOSIS 
283 
more twice daily. Eight hours of sleep with an extra nap 
after the midday meal are necessary. There should be 
no indulgence in alcoholic drinks. 
Evidence that living according to the above plan will 
render one practically safe from tuberculosis is furnished 
Fig. 190. - Sleeping quarters in the foreground at the sanatorium for con- 
sumptives at White Haven. Note that the rooms are wide open to the 
fresh air on three sides. Hundreds of patients have been cured here. 
from three sources. Not one of those who follow these 
rules of life suffer from the disease. Three fourths of 
the half million persons with the disease in this country 
have been overworked or underfed or lived in poorly ven- 
tilated rooms with sunshine shut out. After the disease is 
once established in the body, living according to the above 
rules cures more than half of all those who continue the 
hygienic life, while very few of those who seek help from 
medicine and follow the ordinary mode of living recover. 284 
THE PREVENTION OF DISEASE 
How to cure Consumption. - A pain in the chest, a 
hacking cough, especially in the morning, loss in weight, 
and an evening temperature of about 100 degrees or more 
are strong evidences of consumption if they continue a 
month or more. A physician should be consulted. Long 
experience has shown that patent medicines are of no use 
whatever for the consumptive. Some may seem to help 
for a time because 
of the alcohol or 
other tonic they 
contain, but the 
help is only tem- 
porary, and many 
of them hasten the 
progress of the 
disease. Scientists 
agree that the use 
of any alcoholic 
drink advertised to 
cure consumption 
only makes it worse, because the alcohol has been shown 
to weaken the germ-killing power of the blood. 
The one treatment which has been tried by over 100,000 
patients and found most successful, is living a hygienic 
life to increase the germ-killing power of the blood. 
Keeping in the fresh air by day and by night, drinking 
daily a quart or more of rich milk containing a half dozen 
raw beaten eggs, in addition to eating three nutritious 
meals, and exercising according to strength has cured 
fifty-five per cent of the tubercular patients taking the 
treatment in the early stages of the disease. 
Fig. 191. - Open shed facing southward where 
the consumptive patients breathe pure air all 
day. METHOD OF MAKING THE BODY IMMUNE 
285 
The Danger from a Consumptive.-If proper care is 
taken, there is but little probability of contracting con- 
sumption from living in the same house with a patient. 
No germs are given off in the ordinary breathing, and in 
coughing, a cloth 
to be later burned, 
should be held 
before the mouth. 
The sputum must 
be received into a 
paraffined paper 
cup with a cover 
to keep out the 
flies and burned 
at the end of the 
day. More than 
10,000,000 germs 
are known to be 
given off daily by 
some patients. 
The drinking cup 
and other table 
ware should be 
scalded immedi- 
ately after use. Observing these precautions and living 
a more hygienic life has decreased the yearly deaths from 
tuberculosis in this country one fourth during the last 
fifteen years. 
Artificial Method of Making the Body Immune. - Safety 
from certain diseases is acquired by inoculation with 
antitoxins or vaccines. Inoculation means injecting a 
Fig. 192. - Showing why open spittoons should 
not he used by consumptives or any other 
persons. 286 
THE PREVENTION OF DISEASE 
substance under the skin. In 1880 Pasteur discovered 
that when a healthy chicken was inoculated with cholera 
germs weakened by exposure to the air, the bird became 
only slightly ill instead of dying, as was the case when 
fresh germs were used. When the same bird was inocu- 
lated later with strong 
germs, no sickness 
whatever resulted, be- 
cause the growth of 
weak germs had given 
the body tissues time 
to produce a substance 
destroying the cholera 
germs. This process 
of rendering a person 
immune to a severe 
form of a disease by 
inoculating him with 
weak germs is known 
as vaccination. 
Millions of dollars' 
worth of cattle have 
been saved by vacci- 
nating them against 
anthrax. Since 1904 vaccination of calves against tuber- 
culosis has been tried with great success. 
Vaccination for Smallpox. - About the year 1800 Jen- 
ner, of England, discovered a method of preventing small- 
pox by inoculating a person with the germs of cowpox. 
The cowpox germs are the human smallpox germs after 
they have become weakened by being grown in the 
Fig. 193. - Edwin Jenner, whose discovery 
of the method of vaccination has pre- 
vented millions from suffering from the 
loathsome disease of smallpox. VACCINATION FOR SMALLPOX 
287 
tissues of the cow. Prior to the practice of vaccination, 
smallpox was the worst of human maladies. Scarcely 
any one lived beyond the age of thirty years without be- 
ing attacked by the disease, and one in every seven who 
suffered from it died, while many others were made deaf 
or blind. Macaulay describes its ravages in the follow- 
ing words: " That disease over which science has since 
achieved a succession of glorious and beneficent victories 
was then the most terrible of all the ministers of death. 
The havoc of the plague had been far more rapid ; but the 
plague had visited our shores only once or twice in living 
memory; and the smallpox was always present, filling the 
churchyard with corpses, tormenting with constant fears 
all whom it had not yet stricken, and leaving on those 
whose lives it spared the hideous traces of its power." 
In 1721 more than half of the inhabitants of Boston had 
the disease, and a few years later 18,000 of the 50,000 
residents of Greenland died of this terrible malady. It 
killed 60,000,000 inhabitants of Europe in the eighteenth 
century. 
During the years 1874-1894 Austria, because it 
did not compel its people to be vaccinated, lost 239,800 
of its citizens by smallpox. During the same years 
Prussia compelled vaccination, and lost only 8500 by 
smallpox. 
To-day smallpox is a rare disease, because vaccination 
properly performed absolutely prevents it. In the small- 
pox epidemic of 1902 in Philadelphia none of the 50 
vaccinated nurses caring for the smallpox patients took 
the disease. In Germany, where the law compels every 
person to be vaccinated twice, the deaths from smallpox 288 
THE PREVENTION OF DISEASE 
are only one twentieth as great in proportion to the popu- 
lation as they are in the United States. Every one, unless 
in ill health, should be vaccinated in infancy and again in 
the twelfth year or oftener if near a case of smallpox. 
Hydrophobia, likely to develop from the bite of a rabid 
dog, may be prevented by taking the Pasteur treatment, 
• which consists in 
several vaccinations 
with weak hydropho- 
bia germs. 
Antitoxins. - Other 
means of preventing 
some diseases or cur- 
ing them are by using 
antitoxins secured 
from the blood of 
domestic animals. 
Diphtheria antitoxin 
is secured from the 
horse by inoculating 
it several times at intervals of a day or more with 
some broth in which diphtheria germs have been grow- 
ing and have given off their poisons, called toxins. 
Before the broth is used the germs are removed by a 
filter. Each successive dose given the horse is in- 
creased, and to overcome these constantly larger quan- 
tities of poison, it develops in its tissues a substance 
known as antitoxin. This occurs abundantly in its 
blood, a gallon or more of which is later drawn from 
a vein in its neck. After the corpuscles are allowed to 
settle, the clear part, called serum, containing the anti- 
Fig. 194. - Germs of diphtheria. Photo- 
graphed through the microscope. HOSPITALS AND SANATORIA 
289 
toxin, is put up in tubes and sent out to physicians to 
prevent and cure diphtheria. 
Antitoxin does not affect the heart, as many people sup- 
pose, but the poison of the diphtheria germs does. Anti- 
toxin used in the early stages of the disease is a sure cure 
in nearly all cases. It saves the lives of 45,000 children 
in Germany every year. The mortality from diphtheria 
is only one third as great as in former years. Antitoxin 
saves the lives of more than 10,000 persons annually in 
the United States. In the Boston City Hospital before 
the use of antitoxin 46 per cent of the diphtheria patients 
died, but with the use of antitoxin since 1895 only 12 
per cent die. 
Hospitals and Sanatoria. - In nearly every city in the 
United States with a population of over 20,000 there 
are one or more hospitals. These are institutions with 
nurses, surgeons, and physicians and all appliances for the 
treatment of the sick and wounded. Serious operations 
are usually performed with more safety and less expense 
at the hospital than at the home. The thousands who are 
living in hotels and private boarding houses find the 
hospital a convenient place to receive them in case of 
sickness. A specially equipped wagon, called an am- 
bulance, is kept by most hospitals for conveying the sick 
and injured to the institution. 
Although many persons using the hospitals pay for 
their accommodations, yet there are hundreds who cannot 
afford the expense, and are therefore treated free. A 
department of the public hospitals, known as the dis- 
pensary, furnishes free of charge treatment and medicines 
to the poor making application at certain hours each day. 
DAV. PHYS. 19 290 
THE PREVENTION OF DISEASE 
Public hospitals are largely maintained by the generous 
gifts of benevolent persons or by the government. A 
hospital for taking care of those not in their right mind 
is an insane asylum. Each state usually supports one or 
two such institutions. A sanatorium is a hospital where 
the sick are treated largely by the use of fresh air, nutri- 
tious food, proper exercise, and baths. 
It is not only humane to prevent suffering, but it is 
economy for the government to endeavor to prevent sick- 
ness and cure the sick, because the average work of each 
person done between the ages of 21 and 75 years is worth 
to the country about $4000. The captivity of the Jews 
was delayed 122 years by the plague that fell upon the 
army of Sennacherib. Herodotus, the great Greek his- 
torian, tells us that nothing reduced the Athenian power 
more than the plague or contributed more largely to the 
downfall of Athens. One of the greatest assets of any 
nation is healthy citizens. 
The Board of Health. - In nearly every community 
there are several persons appointed to protect the health 
of the people. These persons constitute the Board of 
Health. One of their number, the health officer, is re- 
quired to see that certain laws are enforced to prevent the 
cause of sickness and the spread of contagious diseases. 
One of his duties is to placard all houses in which are 
contagious diseases, to quarantine the inmates, and to 
disinfect the home after the sick have recovered. 
It is the duty of the health board to see that the gar- 
bage is burned or buried and the sewage properly disposed 
of, to prevent the sale of unhealthful milk and provide for 
a pure supply of water. HEALTH RULES FOR SCHOOL CHILDREN 
291 
All persons should obey the instructions of the board of 
health and endeavor to assist them in preventing much 
sickness which frequently afflicts every negligent com- 
munity. 
HEALTH RULES FOR SCHOOL CHILDREN 
FROM THE MICHIGAN PUBLIC HEALTH QUARTERLY 
1. Health is wealth. 
2. Do not put pins in your mouth. 
3. Do not hold money in your mouth. 
4. Do not put your fingers in your mouth. 
5. Do not put pencils in your mouth or wet them with 
your lips. 
6. Do not wet your finger in your mouth when turning 
the leaves of books. 
7. Do not put anything into your mouth except food 
and drink. 
8. Never spit on your slate, or upon the floor or side- 
walk. 
9. Do not pick your nose, or wipe it with your hand 
or sleeve. 
10. Keep your face, hands, and finger nails clean. 
11. Keep the interior of your body clean by allowing 
nothing to go into it excepting pure, food and pure 
drink. 
12. Don't keep your rubbers on in the schoolroom. 
13. Don't sit with wet feet or damp clothing ; resort to 
the stove or register until they are dry. 
14. Do not swap parts of apples, candy, chewing gum, 292 
THE PREVENTION OF DISEASE 
. half-eaten food, whistles, or anything that is to be 
put in the mouth. 
15. Never cough or sneeze in a person's face. Turn 
your face to one side, and hold a handkerchief 
before your mouth. 
16. When drinking rinse out the cup, and empty what 
water you leave into the wash basin or sink. 
17. Breathe only fresh air day and night - simply avoid 
drafts. 
18. Breathe, sit, stand, and walk correctly. In so doing 
you will do more to prevent consumption than all 
the physicians combined. A good pair of lungs 
is the most efficacious barrier to this disease. 
19. Go to bed early, rise early; and take plenty of 
" physical culture," helping father and mother 
before and after school with the " chores." 
20. Study the physiology - to know how to use rightly 
and take proper care of every part of the body. 
Questions 
1. Name three methods of preventing disease. 2. Why should the 
germs in the excretions of the sick always be killed ? 3. How should 
the excretions be treated? 4. Who are largely responsible for the 
many deaths from typhoid fever? 5. Why should open spittoons not 
be used ? 6. How should the spit of the sick be disposed of ? 7. Why 
and how should those sick with contagious diseases be isolated ? 
8. Name some antiseptics. 9. What is an antiseptic ? 10. Why 
should a room containing a person sick with a contagious disease not 
be swept? 11. How should a room be disinfected ? 12. Explain how 
the person should be disinfected. 13. When one case of typhoid 
occurs in a family, why do other members of the house often get the 
disease? 14. What five kinds of disease germs may usually be kept 
out of the body? 15. How may these germs be kept out of the body? 
16. When should one use only boiled water ? 17. How may the germs SUGGESTIONS FOR THE TEACHER 
293 
of malaria and yellow fever be kept out of the system ? 18. Give two 
differences between the malaria mosquito and the common mosquito. 
19. How may the plague and leprosy be transmitted ? 20. In what 
way are the germs given off by those sick with diphtheria and tuber- 
culosis? 21. Why should every one hold a handkerchief over the 
mouth when coughing? 22. How is water filtered and what is the 
result? 23. What facts show that filtering river water saves much 
sickness and death ? 24. How are disease germs often killed within 
the body? 25. How may the body be rendered safe against some 
diseases? 26. How frequently are the germs of tuberculosis present 
in the body ? 27. Give the number of people dying annually from 
tuberculosis. 28. Explain the method of preventing tuberculosis. 
29. Give evidence showing that hygienic living will in most cases pre- 
vent tuberculosis. 30. Why is it better for tubercular patients to sleep 
out of doors? 31. How may a person often distinguish consumption 
from a cold or catarrh ? 32. Are patent medicine or alcoholic drinks 
of any use in curing consumption? 33. Give three great helps in cur- 
ing consumption. 34. Give evidence showing that in most cases con- 
sumption may be cured in the early stages. 35. Can one live in the' 
same house with a consumptive without danger? 36. What is vacci- 
nation? 37. How is smallpox prevented? 38. State some facts 
showing that smallpox was once a much-dreaded disease. 39. What 
facts show that vaccination for smallpox prevents the disease ? 
40. What care should be used in vaccinating? 41. Where is anti- 
toxin for diphtheria secured ? 42. Of what use is a hospital, a dispen- 
sary, or a sanatorium ? 
Suggestions for the Teacher 
1. Write to the Department of Agriculture, Washington, D.C., for 
bulletins relating to tuberculosis and health. They furnish excellent 
material for short essays by the pupils. 
2. Ask the pupils to find the young of mosquitoes by looking into 
any quiet ponds, tin cans, or barrels containing water. The young 
will hatch into full-grown mosquitoes in a few days if kept in a jar of 
water. Let the pupils suggest plans for destroying mosquitoes. 
3. Ask the pupils to note how many persons spit upon the sidewalk 
and floor of cars and public buildings. Ask the class to think the 
matter over and suggest a remedy for the uncleanly habit. Ask some 
of the boys to count the flies seen feeding in spittoons. XXV. ACCIDENTS AND EMERGENCIES 
Importance of Early Aid. - It is estimated that over 
10,000 people die annually in this country from lack of 
the quick aid after injury which this chapter explains. 
During the late hours of night it is not easy to secure a 
physician in less than an hour, and in the country many 
residents have no doctor within five or more miles of 
them. The most effective aid in cases of fainting, con- 
vulsions, sunstroke, snake bite, croup, choking, bleeding, 
and drowning is that given during the first half hour 
after the person is affected. 
Injuries to the eye and ear are discussed in the chapters 
treating of those organs. Treatment for sprains and dis- 
locations is given in the chapter on bones. 
Fainting. - Fainting may be caused by pain, fatigue, 
loss of blood, the sight of some gruesome object, such as 
flowing blood, or by a hot and badly ventilated room. 
The face is pale, the lips white, and the breathing is 
quickened, while cold sweat appears on the brow and the 
palms of the hands. As fainting is caused by an insuf- 
ficient supply of blood to the brain, the patient should be 
laid flat on the floor. Then the doors and windows must 
be opened and the clothing loosened, while cold water is 
sprinkled on the face. Recovery should occur in a few 
minutes. As soon as the patient is able to swallow, 
294 FITS OR CONVULSIONS 
295 
give sips of hot milk or water. Swallowing stimulates the 
heart. Do not give alcohol. 
Intoxication. - This may be caused by the drinking of 
beer, wine, whisky, hard cider, or patent medicines con- 
taining alcohol. The victim seems half asleep, eyes 
are red and bloodshot and have a fixed stare. The 
breathing is slow, and the smell of liquor is often in the 
breath. The stomach should be emptied by giving the 
patient a tablespoonful of mustard in warm water to 
make him vomit. Then let him sip slowly two or three 
cups of strong hot coffee, after which he may be put to bed. 
Fits or Convulsions. - There are in this country about 
135,000 people w'ho are attacked at intervals of several 
hours or days with epileptic fits. The victim is unable to 
control his muscles and throws his arms and legs in all 
directions. He seems to be in agony, but really does not 
suffer. No remedy is effective. The patient should be 
prevented from injuring himself, and especially from bit- 
ing his tongue, by placing a folded handkerchief between 
the teeth. The fit will last only a few minutes. 
Convulsions or spasms are usually ailments of children 
less than five years of age. They are frequently caused 
by eating indigestible foods, such as fruits and nuts, which 
are not well chewed. The child jerks at first with con- 
tractions of the muscles and then struggles violently. It 
is unconscious, and therefore does not suffer. Relief is 
usually given by placing the feet and legs in water as hot 
as the hand can bear and applying a cloth wrung out of 
cold water to the forehead and temples. The wet cloth 
should be changed every minute or two to keep the head 
as cold as possible. The bowels should be moved. 296 
ACCIDENTS AND EMERGENCIES 
Sunstroke and Heat Exhaustion. - Sunstroke is caused 
by fatigue and exposure to the rays of the sun on a hot 
day. The patient feels giddy at first, then weak and 
sick at the stomach. He may become sleepy and more 
or less unconscious. The eyes are bloodshot and the 
skin is hot and dry. The remedy is to keep the patient 
Fig. 195. - Method of producing artificial breathings 
cool by throwing cold water on the head, neck, and chest 
or by wrapping sheets wrung out of cold water around 
him. Chopped ice wrapped in flannel may be applied to 
the head 
Tn heat exhaustion the skin Is cold and pale, and 
therefore cool applications should not be used. Drinking 
strong hot coffee and rest in bed are most helpful. THE CLOTHING ON FIRE 
297 
Alcoholic drink should never be given for sunstroke or 
heat exhaustion. 
Suffocation from Gas or Drowning. - Suffocation may be 
produced by remaining in a closed room where the gas 
used in lighting is escaping, or by the gas from a coal 
stove when the chimney draft is closed. The first remedy 
is fresh air in abundance. All tight clothing must be 
loosened and artificial respiration begun at once by lay- 
ing the patient face downward with his chest on a thick 
folded coat or blanket. Then stand astride him, and plac- 
ing one hand on either side of the lower ribs, let the 
weight of your body fall forward slowly, and thus press 
out the air in the lungs and mucus in the larynx. The 
hands should not be moved from their places, but the 
pressure should be slowly relaxed by bringing your body 
to a more upright position so that the air will be drawn 
into the lungs. The operator should bend forward and 
backward, pressing on the ribs and relaxing the pressure 
about fifteen times a minute, while another person is 
dashing cold water upon the head and rubbing the body 
to warm it. 
In case of apparent drowning the artificial breathing 
should be begun at once without making any effort to get 
the water out of the internal organs. The wet clothing 
should be removed as soon as possible, and dry blankets 
used with hot bricks to warm the body. Strong hot 
coffee is useful as a stimulant as soon the patient can 
swallow. 
The Clothing on Fire. - To extinguish the burning 
clothing of a person, it is necessary to wrap him in a coat, 
quilt, or blanket so as to exclude the air. Rolling him 298 
ACCIDENTS AND EMERGENCIES 
over and over in the dirt and dust is also effective. As 
the patient is in pain and much excited, he is likely to 
break loose and run out into the open air unless held 
firmly. If the burning is sufficient to cause the clothes 
to adhere to the skin in places, these should be soaked in 
a quart of water to which a teacupful of washing or bak- 
ing soda has been added, while the physician is sent for. 
The slightly burned places may be anointed with vaseline. 
Burns and Scalds. - Hot water or escaping steam may 
cause severe scalds. Burns are produced by fire, hot ob- 
jects, acids, and alkalies. Every household should keep on 
hand a quart bottle filled with one pint of limewater and 
one pint of linseed oil well shaken. This is carron oil, the 
most effective of all remedies for burns and scalds. Linen 
cloths or pieces of lint are soaked in this and applied at 
once to the burn. Cloths spread with vaseline or soaked 
in kerosene or in a pint of water containing a half tea- 
cupful of soda and bound on the injured skin give great 
relief. 
Burns from acids should be first drenched with water 
containing a little soda before the above remedies are 
applied. Burns from alkalies should be washed with 
water containing a little vinegar before using the other 
remedies. 
Frostbite.-Frosted ears, fingers, and toes are very 
common, and often cause much discomfort for several 
weeks if not properly cared for. The parts affected 
should be rubbed with snow or ice water in a cold room 
until a tingling sensation is felt. This shows that the 
circulation which had stopped has returned, and the 
patient may then be brought nearer a warm stove. BRUISES 
299 
Cuts and Nail Punctures. -A small cut or the puncture 
of the skin by a nail has been known to result in death. 
This was due to bacteria, which cause the pus or white 
matter in a sore. If a wound bleeds freely, the germs are 
likely to be washed out. In case the skin is torn or 
punctured by a blunt instrument like a nail the wound 
should be well washed 
out by forcing into it 
with a syringe tur- 
pentine or a five per 
cent solution of car- 
bolic acid. A clean 
linen cloth folded sev- 
eral times should then 
be laid over the wound 
and tied firmly in place. 
If the wound causes 
a considerable flow of 
blood, it should be 
stopped, as directed 
in the chapter on the circulatory system. Do not use 
unboiled water or a soiled cloth or hands in cleaning a 
wound. 
Bruises. - These result from blows on the person with 
blunt instruments. The part affected swells and becomes 
more or less black and blue, owing to the bursting of the 
blood vessels. The dark coloration may be prevented to 
a certain extent by applying for a half hour cloths wrung 
out of very hot water. The cloths should be changed 
every two or three minutes. Cold water will serve 
almost as well as hot water. 
Fig. 196. - Bacteria which get into wounds 
and produce blood poison. 300 
ACCIDENTS AND EMERGENCIES 
Bleeding from the Nose. - This is rarely dangerous, and 
no remedy is necessary unless the blood continues to flow 
for an hour or more. The patient should not lean over, 
but sit erect or with the head thrown slightly backward 
and use a damp cloth to soak up the blood. Broken ice 
tied in a cloth and applied to the back of the neck and 
between the shoulder blades is the best remedy. Cloths 
Fig. 197. - How a copperhead snake, or pilot sinks its poison fangs or teeth 
into the flesh. 
wrung out of cold water may be held to the back of the 
neck and over the nose and forehead. If bleeding con- 
tinues, the nose should be held shut and the mouth used 
in breathing. 
Bites and Stings of Animals. -The bite of a healthy dog 
or cat should be treated like any other wound. If there 
is any reason to suppose the dog is rabid, a physician 
should be called to cauterize the bite and arrange to 
vaccinate the patient for hydrophobia. 
The bite of a venomous or harmful snake, such as a copper- 
head, rattlesnake, or moccasin, usually results in death in CHOKING 
301 
from 12 to 24 hours unless some remedy is used. A physi- 
cian should be called at once. The best means of avoiding1 
o 
serious results if the bite is on a limb is to tie just above 
the punctures a loose bandage and twist it tight by turn- 
ing a stick slipped underneath. Then a cut lengthwise 
of the limb two inches long and nearly a half inch deep 
should be made through the wound to let out the poi- 
soned blood and lymph. The application to the bite of 
crystals of permanganate of potash is of great value. If the 
physician does not arrive soon, the taking of a tablespoon- 
ful of aromatic ammonia at half-hour intervals until the 
patient feels the effect tends to keep up the heart action. 
Some of the snakes, such as the water snake, without any 
poison, bite sufficiently to make the blood run, but no 
serious results follow. The bite of a poisonous snake can 
be recognized by the presence of two little holes made by 
the two fangs in the upper jaw of the reptile. The bite 
of a spider need cause no alarm unless it is one of the 
large Southern spiders. 
The stings of wasps and bees are not dangerous, but may 
cause considerable swelling and pain. This may be re- 
lieved by bathing the part in ammonia or a strong solution 
of baking soda in water. 
Choking. - The lodging of a button, thimble, or a piece 
of meat in the throat may cause death in a few minutes. 
A blow with the fist on the back between the shoulder 
blades will cause the air to rush out of the lungs and 
sometimes expel the object. If the sufferer is a child, it 
should be held by the feet with the head hanging down- 
ward while two or three blows are struck on the back of 
the chest. 302 
ACCIDENTS AND EMERGENCIES 
Sometimes the object is in the upper part of the throat 
and may be pulled out with the finger or the end of a 
bent spoon handle. When hard objects, like keys or 
tacks, are swallowed, plenty of hard-boiled eggs, bread, 
and potatoes should 
be eaten. These will 
prevent the jagged 
points of the object 
from injuring the in- 
testine. 
Croup. - There are 
two kinds of croup. 
False or catarrhal croup 
usually comes on sud- 
denly at night. The 
child has a hoarse 
metallic cough and 
may at times have to 
gasp for breath. Re- 
lief may be quickly 
given by making a 
tent of a sheet or 
quilt in which the 
child should be held, 
while a tin cup partly filled with a mixture of equal parts 
of vinegar and water is kept boiling or very hot on an 
oil stove in the tent. A common lamp may be used to do 
the heating if two nails for the support of the cup are 
laid across the top of the chimney to prevent smoking. 
Membranous croup is a form of diphtheria in which there 
is a membrane formed in the narrow part of the throat. 
Fig. 198. - The death cup, a poisonous mush- 
room which has killed more people than 
any other. The different forms show the 
plant at different ages. SPECIAL POISONS 
303 
Poisons and Emetics. - An emetic is a substance which, 
when taken into the stomach, causes vomiting. Since the 
first step in treating a person poisoned is usually to free the 
stomach of its contents, an emetic must be given. It is 
well to remember that no 
emetic should be used when 
from stains or burns on the 
fingers, lips, or mouth, or 
by any other means it is 
known that the person has 
taken a strong alkali or 
an acid. 
The following are good 
emetics: a tablespoonful of 
mustard in a glass of warm 
water; two tablespoonfuls 
of common salt in a glass 
of warm water; a pint of 
warm water followed by 
tickling the back of the 
throat with a feather or 
other soft object. Poisons 
cause the death of about 
8000 persons annually. 
Special Poisons. - The remedy for carbolic acid poisoning 
is a tablepoonful of " salts," properly called Epsom salts, or 
sulphate of magnesia, in a glass of warm water. Im- 
mediately after a pint or two of milk should be swallowed. 
A cup of strong coffee may then be given to stimulate the 
heart. Ammonia or potash poisoning may be helped by 
giving the patient the juice of two or three lemons or 
Fig. 199. - Water hemlock, whose 
poisonous roots have killed a num- 
ber of children. The height of the 
plant is from three to five feet and 
the leaves are two or three inches 
long. 304 
ACCIDENTS AND EMERGENCIES 
oranges, or a glass of water containing two tablespoonfuls 
of vinegar. 
Arsenic poisoning is common, as this poison forms a part 
of Paris green, many rat poisons, and preserving fluids. 
After giving an emetic, a glass 
or two of soapy or greasy water 
should be taken. A cup of 
water which has been several 
days in a -rusty kettle or con- 
tained rusty nails or iron of 
any kind should be drunk. 
Certain plants found grow- 
ing in yards and fields contain 
strong poisons. The deadly 
nightshade, some kinds of 
mushrooms, holly berries, jimson 
weed, and water hemlock have 
caused the deaths of many 
persons, especially children. 
The roots, berries, or leaves of 
wild plants should never be 
chewed or eaten unless they 
are known to be harmless, as 
there are more than thirty 
poisonous plants growing in the United States. The 
best remedy for their poisons is an emetic, followed by 
a large dose of Epsom salts to cause the harmful materials 
to pass out of the alimentary canal. A physician should 
be called at once. 
The external poisoning of the skin by poison ivy or sumac 
often results seriously. Numerous pimples or blisters 
Fig. 200. - Poison ivy, which is 
common along old fences and 
in waste places. Touching it 
or sometimes even coming 
near it poisons the skin of 
many persons. SUGGESTIONS FOR THE TEACHER 
305 
may form with more or less redness and swelling, some- 
times sufficient to close the eyes. Poison ivy may be 
distinguished from similar vines by the division of each 
leaf into three leaflets instead of five. If one has been 
touching the plant, poisoning may usually be prevented 
by washing as soon as possible the face and hands with 
soapsuds. A good remedy for the poison is the applica- 
tion to the affected parts of a cloth soaked in a hot one per 
cent solution of permanganate of potash in water. If the 
skin is not broken use a two per cent solution. 
Questions 
1. Why should every one understand howto give first aid to the 
injured? 2. What may cause fainting? 3. How should a fainting 
person be treated ? 4. What is the remedy for intoxication? 5. What 
is the treatment for epileptic fits? 6. How can you tell when a 
child is having a spasm? 7. Explain the treatment for a spasm. 
8. Describe the difference between sunstroke and heat exhaustion. 
9. How is a patient to be treated in case of suffocation ? 10. Explain 
the relief for scalds and burns. 11. What is the remedy for frost- 
bite? 12. Describe the treatment for cuts and nail punctures. 
13. How should a bruise be treated? 14. Give some methods for 
stopping the flow of blood from the nose. 15. Why is the bite of a 
black snake, garter snake, or common water snake harmless ? 16. How 
is the bite of a copperhead or rattlesnake to be treated ? 17. Describe 
the relief for choking. 18. How does false croup differ from mem- 
branous croup? 19. What relieves false croup? 20. Name some 
emetics. 21. Of what use are emetics ? 22. When should an emetic 
not be given ? 23. What is the remedy for carbolic acid poisoning ? 
24. Name some poisonous plants. 25. Explain how poisoning of the 
skin by poison ivy may be relieved. 
Suggestions for the Teacher 
Any one able to render efficient first aid to the injured is a valuable 
person in any community. It is worth while for the teacher to take 
time to impress upon the children what to do when the various 
DAV. PHYS. - 20 306 
ACCIDENTS AND EMERGENCIES 
common accidents of life occur. This may be done by full and clear 
explanations followed by careful questioning of the pupils. Actual 
demonstrations of how to proceed in case of certain accidents, such as 
fainting, choking, burns, and wounds, may be given, using some pupil 
for the subject. 
Permitting the children to tell of accidents that have occurred in 
their own families and the results of the wrong or right treatment 
given, may often help to emphasize the importance of understanding 
what this chapter teaches. Procure from the Department of Agricul- 
ture at Washington the free pamphlets on poisonous plants and 
mushrooms. PRONUNCIATION AND EXPLANATION OF 
DIFFICULT WORDS 
Ab do'men : that part of the body between the chest and legs. 
Ab dom'i nal: pertaining to the abdomen. 
Ad'e noids: spongy growths in the upper part of the throat back of 
the nose. 
A dul ter a'tion: making any substance impure by mixing with it 
something of less value. 
Al bu'min: one kind of proteid. It occurs in all cells of the body. 
Al'co hoi ism : a diseased condition of the body caused by using much 
strong drink. 
Am'bu lance : a wagon for carrying the sick. 
A moe'ba: a tiny one-celled animal which is constantly changing its 
shape. 
A moe'boid: like an amoeba. 
A nat'o my : the study treating of the parts of the body. 
An ti sep'tic : that which stops the growth of bacteria. 
An ti tox'in: a substance which prevents certain poisons from harm- 
ing the body. Anti means against, and toxin, a poison. Anti- 
toxin for diphtheria makes the poison given off by the diphtheria 
germs harmless. 
Ap'o plex y: sudden loss of motion and fainting caused by the clog- 
ging or bursting of a blood vessel in the brain. 
Ap pend i ci'tis : an inflammation of the vermiform appendix. 
A'que ous (a'kwe us) : the kind of humor or watery fluid in the front 
part of the eyeball. 
A rach'noid (a rak'noid) : a delicate membrane covering the brain 
and spinal cord. 
Asth'ma (as'ma) : a disease in which the air tubes are squeezed so 
tight by their muscles as to hinder proper breathing. 
A stig'ma tism: a condition of unequal curvature in the lens or 
cornea. 
307 308 
PRONUNCIATION AND EXPLANATION OF WORDS 
Au'di to ry: relating to the ear. 
Ax'on : the long process of a nerve cell carrying the stimulus from the 
cell body. 
Bacil'li: rodlike bacteria such as the germs of diphtheria and con- 
sumption. 
Ba cil'lus: singular of bacilli. 
Bac te'ri a: tiny one-celled plants often called germs or microbes. 
Bi cus'pid: another name for a premolar tooth, also the valve on the 
left side of the heart. 
Brach'i al (brak'i al) : pertaining to the arm. 
Bron'chi (bron'ki) : plural of bronchus. 
Bron'chi al tubes (bron'kl al) : the air tubes of the lungs. 
Bron chi'tis (bron ki'tis) : inflammation of the bronchial tubes. 
Bron'chus (bron'kus) : one of the two branches of the windpipe enter- 
ing the lungs. 
Caf fe'in: a bitter substance in coffee and tea. 
Cal'o rie : a heat unit. 
Ca nine' teeth: the stomach or eye teeth. 
Cap'il la ry: the smallest blood tube. 
Car bo hy'drate: any food stuff made mostly of starch or sugar. 
Car bol'ic ac'id : a poison which burns the skin. It is used as a disin- 
fectant. 
Car'di ac : near to or belonging to the heart. 
Ca'se in: the proteid in milk and cheese. 
Ce ment': the substance covering the dentine in the roots of the teeth. 
Cer e bel'lum : the little brain ; the large lobe of the hind brain. 
Cer'e brum: the large part of the brain. 
Chol'e ra infan'tum: a dangerous disease of children usually caused 
by impure milk, or dirty milk bottles. 
Cho'roid (ko'roid) : the middle coat of the eyeball. 
Chyle (kile) : the digested food in the intestine. 
Chyme (kime) : the partly digested food leaving the stomach. 
Cil'i a: tiny hairlike projections in the nose and air tubes. They 
catch dust particles and mucus, and move them outward by con- 
stantly waving. 
Clav'icle: collarbone. 
Co'ca ine (ko'ka in) : a narcotic made from coca leaves. 
Coc'ci (kok'si){ spherical bacteria. PRONUNCIATION AND EXPLANATION OF WORDS 
309 
Coc'cyx (kok'siks) : the small bone at the end of the spinal column. 
Coch'le a (kok'le a) : coiled part of the internal ear. 
Com'mis sure: a band of fibers in the brain or spinal cord. 
Con sti pa'tion: a condition in which the refuse part of the food hardens 
and is not easily expelled daily from the large intestine. 
Con sump'tion : tuberculosis of the lungs. 
Con ta'gious (con tabus') : catching. 
Cor'pus cal lo'sum: a band of fibers joining the two halves of the 
cerebrum. 
Cor'pus cle (cor'pus s'l) : a blood cell. 
Cra'ni al: pertaining to the cranium. 
Cra'nium : the bones surrounding the brain. 
Den'tine (den'tin) : the hard inner part of the teeth. 
Di'a phragm (di'a from) : the muscle separating the cavity of the chest 
from that of the abdomen. 
Di ar rhe'a: a condition in which the bowel excretions contain too 
much liquid. 
Di as'to le : the expanding of the walls of the heart. 
Di'et: a course of food. 
Dis in fect'ant: a substance which kills germs. 
Dis pen'sa ry: a place where the poor receive free medical advice. 
Dys'en ter y: inflammation of the large intestine with the discharge 
of some blood. 
Dys pep'si a : a failure to digest the food properly. 
E met'ic: an agent which causes vomiting. 
E mul'sion : a liquid full of fine particles of fat. 
Ep i the'li um: the layer of cells covering a free surface. 
E soph'a gus (e sof a gus) : the tube taking the food from the throat to 
the stomach. 
Eu sta'chi an tube (u sta'ki an)-, the tube from the throat to the 
middle ear. 
Ex cre'ta : the natural discharges from the body. The excreta of the 
bowels are called feces. 
Fel'on: an inflammation of the periosteum. 
Fem'o ral: pertaining to the femur. 
Fi'brin: a proteid in coagulated blood. 
Fi brin'o gen: the substance in the blood from which fibrin is formed. 310 
PRONUNCIATION AND EXPLANATION OF WORDS 
Fis'sure (^sh'ur) : a crevice between the parts of an organ. 
Fo'cus : the point where the rays of light meet after passing through 
a lens. 
Fol'li cle (fol'li k'l) : a little pouch. 
For mal'de hyde: a germ-killing gas. The gas dissolved in water 
makes formaldehyde solution or formalin. 
For'mal in: a solution of formaldehyde gas in water. It is a much 
better disinfectant than sulphur. 
Germs: bacteria and also tiny animal parasites. 
Gly'co gen : animal starch. 
Grippe (grip) : a contagious disease often called influenza. 
Hem o glo'bin : the red coloring matter of red blood corpuscles. 
Hem'or rhage (hem.'or raj) : flow of blood from a vessel. 
He pat'ic : pertaining to the liver. 
Hy'dro gen: a gas forming two thirds of water. 
Hy gi en'ic : healthful. 
Il'i ac: pertaining to the ilium or top of the hip bone. 
Im bi bi'tion (im bi bish'un) : drinking in. 
Im mune': safe from disease. 
In ci'sors : front teeth. 
In flam ma'tion: the condition of a tissue which becomes gorged with 
blood as a result of irritation, usually by germs. 
In oc u la'tion: planting the germs of disease in the body. 
In vol'un ta ry : unable to control. 
I'ris: the colored curtain around the pupil admitting light to the eye, 
Ju'gu lar vein : the large vein in the neck. 
Lach'ry mal (lak'ri mal) : the name of the tear gland and its duct. 
Lac'te als : that part of the lymphatic system carrying the food from 
the intestines to the thoracic duct. 
Lar'ynx (lar'inks) : the voice box at the top of the windpipe. 
Lau'da num: a solution of opium in alcohol. 
Lu'pus: tuberculosis of the skin. 
Lym phat'ics: small vessels for returning escaped blood to the veins 
in the neck, and carrying food from the intestines. 
Ma la'ri a: a disease attended with chills and fever. 
Mas'sag ing (mas'saj ing) : pressing and squeezing any part of the 
body in a definite way. PRONUNCIATION AND EXPLANATION OF WORDS 
311 
Me dul'la ob Ion ga'ta : the stem of the brain. 
Med'ul la ry : the name given to the cavity in a long bone. 
Men in gi'tis: an inflammation of the membranes of the brain or 
spinal cord caused by bacteria such as germs. 
Mi'crobes: bacteria and other germs. 
Mi'tral: the bicuspid valve in the heart on the left side. 
Mo'tor: the name of those nerves and that part of the brain control- 
ling the muscles of the body. 
Mu'cous mem'brane: that which lines cavities of the body touched by 
air. 
Mu'cus: the secretion of glands in the mucous membrane. 
Neu'ron: a nerve cell with all its processes. It may be three feet 
long. 
Nic'o tine (nic'o tin) : the poison in tobacco. 
Ni'tro gen: a gas forming four fifths of the air. 
Ni trog'e nous (ni troj'e nous) : said of foods containing much proteid. 
Peas, milk, beans, and lean meat are nitrogenous foods. 
Oc cip'i tai (ok sip'i tai) : name of a bone at the back of the head. 
0 le o mar'ga rine : a substitute for butter. It is made of tallow or 
lard churned with milk and cotton-seed oil. 
01 fac'to ry : pertaining to the nose. 
Op'tic: relating to the eye. 
Or'bit al cav'i ty: the cavity for the eyeball. 
Or'gan: any part of the body having a definite work to perform. 
Os mo'sis: the oozing of a liquid through a membrane, separating it 
from another liquid. 
Ox i da'tion: the union of another substance with oxygen. 
Ox'i dize: to burn or unite with oxygen. 
Pa pil'la: a little elevation on the skin or mucous membrane. 
Pa ral'y sis: loss of power to move or feel in any part. It is caused 
by injury to the nerves, cord, or brain. 
Par'a sites: animals or plants that feed upon other living animals or 
plants without at once destroying them. 
Par e gor'ic : a solution of water, alcohol, opium, and other drugs. 
Pa ri'e tai: a bone on the side of the head. 
Pa rot'id: the salivary gland below the ear. 
Pas'teur: the world's greatest benefactor. lie discovered the cause 
and prevention of disease. 312 
PRONUNCIATION AND EXPLANATION OE WORDS 
Pas teur i za'tion: heating a substance to about 160 degrees for a 
sufficient time to kill most of the germs. 
Patent med'i cines: secret preparations advertised to cure disease; 
most of them are worthless and many are very harmful to health. 
Pep'sin: a digestive ferment made in the stomach. 
Pep'tone : a digested proteid. 
Per i car'di um: the membrane around the heart. 
Per i os'te um: the membrane around the bone. 
Per i stal'sis: the movements of the intestines. 
Peritone'um: the delicate membrane lining the abdominal cavity 
and holding the organs in place. 
Per i to ni'tis : inflammation of the peritoneum. 
Pha lan'ges: the bones of the toes and fingers. 
Phar'ynx (far'inks) : the cavity of the throat. 
Phthi'sis (thi'sis) : tuberculosis of the lungs. 
Poste'rior: behind. 
Pro'te id: a substance forming most of the dry part of the muscle. 
Pro'to plasm: the chief part of every cell in plants and animals. 
Pto'ma ine (to'ma in) : a poison developed by bacteria in stale or 
canned food. 
Pul'mo na ry : relating to the lungs. 
Quack doc'tors: dishonest persons who advertise that they can cure 
disease. 
Ret'i na: the inner coat of the eye. 
Sa'crum: the bone between the hips ; part of the spinal column. 
Sa li'va: the slippery fluid used to moisten the food in the mouth. 
Sabi va ry glands: those glands in the head forming saliva. 
Scle rot'ic (skle rot'ic) : the tough outer coat of the eyeball. 
Scrof'u la: tuberculosis of the lymph glands. 
Se'rum: the clear part of blood clotted in a cup or other vessel. 
Ses'amoid bones: small bones formed about the joints in the hands 
and feet and at the knee. 
Spu'tum: the spit. 
Stim'u lant: that which hastens the action of an organ without later 
slowing it. 
Stim'u lus: an impulse or excitement carried by a nerve fiber. 
Sul'ci (sul'si) : the crevices between the folds on the surface of the 
brain. 313 
PRONUNCIATION AND EXPLANATION OF WORDS 
Syn o'vi a: the slippery fluid in all movable joints. 
Sys'to le: the contraction or squeezing together of the walls of the 
heart. 
Tac'tile (tac'tiT) : pertaining to touch. 
Tho rac'ic (tho ras'ik) : pertaining to the thorax or chest. 
Tis'sue (tish'u) : a combination of cells or of cells and fibers. 
Ton si li'tis: a contagious disease of the tonsils. 
Tra'che a (tra'ke a) : the windpipe. 
Trich i no'sis: a disease caused by little worms. 
Tym'pa num: the middle ear. 
U re'a: the chief solid in urine. 
Ure'ter : one of the two tubes from the kidneys to the bladder. 
U'rine (u'rin) : the excretion of the kidneys. 
U'vu la: back part of the soft palate. 
Vac'ci nate: to prevent disease by putting into the body through the 
skin, weakened germs or the excretions of the germs causing that 
disease. 
Vac'cine : smallpox germs weakened by growing in calves. 
Ver'te bra: one of the bones of the spinal column. 
Vis'cera: the internal organs. INDEX 
Abdominal cavity, 76. 
Absorption of food, 98-101. 
Accidents, treatment for, 294-305. 
Accommodation of eye, 249, 251. 
Acids, 29. 
Adam's apple, 81, 134. 
Adenoids, 136, 146, 147. 
Adipose tissue, 24. 
Adulteration of food, 42, 43, 62. 
Air, composition of, 151, 152; impur- 
ities in, 153, 154; in relation to 
health, 151-162. 
Air cells, 138. 
Albumin, 23. 
Alcohol, 38, 51, 71, 72, 74, 75: and 
crime, 170, 171; and disease, 131, 
168, 169, 269-271, 284; danger 
from, 172, 173; effect on blood, 
281; on bones, 201; on circulatory 
system, 130, 131; on heart, 120, 
168, 169; on heredity, 235, 236; 
on kidneys, 178; on mind, 235 ; on 
muscles, 211, 212; on nervous sys- 
tem, 234-236; on respiratory sys- 
tem, 148, 149; on sense organs, 
256. 257; on skin, 189; poisoning 
by, 295. 
Alcoholic drink, 96, 104; effect on 
the race, 165-174. 
Alcoholism, 260. 
Alimentary canal, 76-85. 
Alkalies, 29. 
Ambulance, 289. 
Amceba, 107. 
Amceboid motion, 107. 
Anatomy, meaning of, 9. 
Ankle, bones of, 193, 194. 
Anthrax, 261. 
Antiseptic, 274. 
Antitoxin, 282. 
Aorta, 20, 116. 
Apoplexy, 130, 230. 
Appendicitis, 85, 267. 
Appendix, vermiform, 77, 84. 
Aqueous humor, 247, 248. 
Arsenic poisoning, 304. 
Arteries, 118, 120, 121. 
Artery, structure of, 119. 
Articulation, 200. 
Artificial breathing, 143, 144. 
Asthma, 144. 
Astigmatism, 252. 
Atlas, 192. 
Auricles, 116. 
Axis, 192. 
Axon, 219. 
Bacilli, 248. 
Bacteria, 16, 29, 46-52, 261, 263, 
279; beneficial, 32, 33, 34, 51; dis- 
ease-producing, 49-51; in air, 154; 
in blood, 112; in breath, 156; in 
milk, 13, 51, 54, 58-64; in mouth, 
48, 81 ; in soil, 48; in water, 48, 
266-268; killing of, 49, 280. 
Baldness, 183. 
Bathing, 187, 188. 
Beef tea, 38. 
Beer, 72, 96, 97, 120, 130, 168. 
Bile, 97. 
Bladder, 20, 176. 
Bleeding, 129, 300. 
Blister, 180. 
Blood, 106-112; corpuscles of, 105- 
109; plasma, 109; poisoning of, 
50, 264; serum, 110. 
Blood vessels, 118. 
Blushing, 223. 
Boils, 51, 268. 
Bone, parts of, 194, 195; structure, 
196. 
Bones, 191-202; development of, 
196; diseases of, 199 ; dislocation 
of, 201; of ear, 242. 
Brain, 215-218, 226-227; exercise 
of, 231; weight of, 230, 231. 
315 316 
IN DEX 
Breakfast foods, 43. 
Breathing, 138-145, 150. 
Bright's disease, 178. 
Broken bones, 198. 
Bronchi, 137. 
Bronchioles, 137, 138. 
Bruises, 299. 
Bubonic plague, 264, 267. 
Burns, 298. 
Butterine, 43. 
Buttermilk, 57. 
Caffein, 73. 
Cancer, 186. 
Capillaries, 108, 121, 122. 
Carbohydrates, 23, 26, 27, 36, 102, 
165. 
Carbolic acid, 303. 
Carbon, 29, 34. 
Carbon dioxide, 25, 27, 152, 153. 
Carpus, 194. 
Cartilage, 196. 
Casein, 24, 55, 56. 
Cataract, 256. 
Catarrh, 146. 
Cells, 14, 15, 16, 18, 21. 
Cerebellum, 216, 217, 226. 
Cerebrum, 216-219, 226. 
Certified milk, 61. 
Cheese, 37. 
Chicken pox, 264, 277. 
Chocolate, 74. 
Cholera, 264. 
Cholera infantum, 62, 269, 276. 
Choroid coat, 247. 
Chyle, 97. 
Chvme, 93. 
Cigarettes, 70, 71, 148, 149, 233. 
Cilia, 16. 
Ciliary muscle, 249, 251. 
Circulatory system, 114-131. 
Clavicle, 192,' 193. 
Clothing, 142, 188, 189. 
Coagulation, 24, 27. 
Cocaine, 71, 72. 
Coccyx, 191, 192. 
Cochlea, 241, 242. 
Cocoa, 74. 
Coffee, 73. 
Colds, prevention of, 188, 189. 
Color blindness, 253. 
Complexion, 184, 185. 
Compound, 29. 
Condepsed milk, 58. 
Condiments, 37. 
Connective tissue, 19. 
Constipation, 42. 
Consumption, see Tuberculosis. 
Contagious diseases, 259, 260, 264. 
Convulsions, 295. 
Cooking, 44. 
Corn, 180, 181. 
Cornea, 247, 249. 
Cranial nerves, 217, 220, 221. 
Cranium, 191, 192. 
Cream, 57. 
Croup, 302. 
Cutis, 178. 
Cuts, 299. 
Dandruff, 184. 
Deafness, 243, 244. 
Decay, 51. 
Diabetes, 88. 
Diaphragm, 76, 77, 209. 
Diet, 40, 42. 
Digestion, 89 ; intestinal, 96; stom- 
ach, 92-94. 
Digestive organs, 76-88. 
Diphtheria, 49, 51, 63, 64, 146, 264, 
272, 282, 283. 
Disease, cause of, 49-51, 260-262 
contagious, 259-269; infectious, 
260; prevention of, 272-293. 
Disinfectants, 273, 274. 
Disinfection, 273, 274, 275. 
Dislocation, 201. 
Dispensary, 289. 
Drinking cup and disease, 260, 261, 
263, 285. 
Dropsy, 129. 
Drowning, treatment for, 144, 296, 
297. 
Duct, 85. 
Dysentery, 264, 276. 
Ear, 241-243 ; care of, 243. 
Ear drum, 241. 
Eggs, 44, 53; use of, for tuberculosis, 
284. 
Emetics, 303. 
Emulsion, 25, 27. 
Epidermis, 178. 
Epiglottis, 134, 135. INDEX 
317 
Epilepsy, 295. 
Epithelium, 16, 18. 
Esophagus, 20, 82, 83. 
Eustachian tube, 134. 
Excreta, disposal of, 279. 
Excretions, 177, 181. 
Excretory system, 175-187. 
Exercise, 209, 210, 213, 231. 
Expiration, 139. 
Extensor muscles, 206, 208. 
Eye, 246-253. 
Eyeball, 247. 
Eyes, care of, 253-255, 256; testing, 
251. 
Fainting, 294. 
Farsightedness, 252. 
Fat, cells of, 16, 17, 103; making of, 
103, 104; use of, 25, 38. 
Fats, 22, 24, 25, 26, 37. 
Felon, 199. 
Femur, 192, 193, 194. 
Fermentation, 51, 165. 
Ferments, 90, 93, 97, 110. 
Fibrin, 110. 
Fibula, 192, 193, 194. 
Filtration of water, 278. 
First aid, 13, 294. 
Fits, 295. 
Flexor muscles, 206, 208. 
Flies and disease, 268, 273, 274, 285. 
Focus, 248. 
Food, 35-45 ; adulteration of, 42-44, 
62; cooking of, 44; digestion of, 
90, 95; preserving of, 46, 52. 
Food stuffs, 35. 
Formaldehyde, 13, 273, 275. 
Formalin, i3, 273. 
Fracture of bone, 198, 199. 
Fresh air and disease, 161, 284. 
Frostbite, 298. 
Fruits, 42. 
Gall bladder, 88. 
Ganglia, 221. 
Gastric glands, 86, 87; juice, 93. 
Germs, 47, 50, 61, 262, 264, 265; of 
air, 154; of body, 280; of disease, 
49, 279, 281, 288; of milk, 262- 
268; of sewage, 279; of water, 
266, 267, 270. 
Gland, nature of, 85. 
Glands, digestive, 85-88, 87, 93 
intestinal, 87; sebaceous, 182 
sweat, 179, 181; thyroid, 112. 
Glasses, 251, 252, 255. 
Gluten, 24. 
Glycogen, 102. 
Grippe, 264. 
Habits, 232. 
Hair, 183, 184. 
Haversian canals, 195, 196. 
Headache, 95. 
Health, rules of, 291. 
Health board, 230. 
Hearing, 243, 245. 
Heart, 114-120; beating of, 118. 
Heat, making of, 38, 132. 
Heat exhaustion, 296. 
Heating rooms, 159. 
Hemoglobin, 106. 
Hemorrhage, 129. 
Heredity, 235, 236. 
Hip bone, 192, 193, 199. 
Hookworm disease, 269, 273. 
Hospital, 289. 
Hydrogen, 30, 34. 
Hydrophobia, 13, 264, 269, 282, 288. 
Humerus, 192, 193, 194. 
Humors of eye, 247, 248. 
Immunity, 281. 
Incubation period, 263, 264. 
Infectious diseases, 49, 259-269. 
Inoculation, 285. 
Insects and health, 13, 268, 273, 285. 
Inspiration, 139. 
Intestines, 82, 84-87; movements of, 
97; structure, 99. 
Intoxication, 295. 
Involuntary muscles, 203, 204. 
Iris, 247, 248, 249. 
Iron, 23, 36, 106. 
Ivy poisoning, 304, 305. 
Jenner, 286. 
Joint, 199, 200. 
Kidneys, 77, 175-177. 
Kneecap, 192. 
Lachrymal gland, 253. 
Lacteals, 99, 100, 125. 318 
INDEX 
Lard, 24. 
Larynx,134-136. 
Laws on prohibition, 166. 
Lens, 248, 250. 
Leprosy, 264, 277. 
Ligament, 200. 
Light, 249. 
Liver, 70, 77, 87, 88. 
Lockjaw, 259, 260, 264, 268. 
Lungs, 136-144; diseases, 146; ex- 
ercising, 145. 
Lymph, 109, 127. 
Lymphatics, 124-129. 
Lymph glands, 126, 127. 
Lymph nodes, 126, 127. 
Malar, 192. 
Malaria, 264, 269, 276. 
Malaria germs, 155. 
Mandible, 192. 
Massaging, 210. 
Mastication, 91. 
Maxillary, 192. 
Measles, 264. 
Medulla oblongata, 216, 226. 
Medullary canal, 195. 
Membranous croup, 146. 
Meningitis, 266. 
Metacarpals, 192. 
Metacarpus, 194. 
Metatarsals, 192, 193. 
Metatarsus, 194. 
Microbes, 46-53. 
Microscope, 15 
Milk, 54-66 ; bulletins on, 13 ; care 
of, 60-61; diseases conveyed by, 
54, 62-65, 26S; food value, 55- 
57; germs in, 58-64 ; pasteuriza- 
tion of, 65-66; souring of, 51, 
58. 
Milk teeth, 78, 79. 
Mind, 231. 
Mineral matter, 22, 23, 27. 
Molds, 46, 47, 48. 
Moles, 186. 
Morphine, 71, 72. 
Mosquitoes and disease, 269. 
Motor nerves, 220. 
Mouth, 77-82. 
Mucous membrane, 77. 
Mucus, 77, 133. 
Mumps, 264, 277. 
Muscles, 202-213; fibers of, 18; in- 
voluntary, 203, 204. 
Mushrooms, poisonous, 302. 
Nails, care of, 185, 186. 
Narcotics, 68-75; effect on bones, 
201; on sense organs, 256-257. 
Nasal passages, 133. 
Nearsightedness, 251. 
Nerve cell, 16, 17, 218, 219, 225, 226. 
Nerve endings, 179, 238. 
Nerves, 214, 215, 220-222. 
Nerve tissue, 19. 
Nervous svstem, 214-245. 
Neuron, 1*6, 218, 219. 
Nicotine, 68-71. 
Nitrogen, 33, 151. 
Nucleus, 14. 
Occipital, 192. 
Oils, 24. 
Oleomargarine, 43. 
Opium, 71. 
Opsonins, 280. 
Orbital cavity, 192, 246. 
Organ, 19. 
Osmosis, 100, 103. 
Oxidation, 31. 
Oxidized, 32. 
Oxygen, 31, 151. 
Pain, 239. 
Palate, 81, 134. 
Pancreas, 88. 
Paralysis, 130, 230. 
Parasites, 259. 
Paregoric, 71. 
Parotid gland, 86. 
Pasteur, 260, 261, 286. 
Pasteurization, 65, 66. 
Patent medicines, 71-73, 75, 166. 
Pepsin, 87. 
Peptones, 93. 
Pericardium, 114. 
Periosteum, 195, 202. 
Peristalsis, 97. 
Peritoneum, 76. 
Peritonitis, 264. 
Perspiration, 182. 
Phalanges, 192, 193, 194. 
Pharynx, 81, 82, 133, 134. 
Phthisis, 266. INDEX 
319 
Physiology, 9, 10, 
Plasma, 106, 109. 
Pleura, 76, 138. 
Pleurisy, 138. 
Plexus,'221, 222. 
Pneumonia, 146, 169, 264, 272, 279. 
Poisoning from canned food, 52. 
Poisonous plants, 304. 
Poisons, remedy for, 303. 
Pons Varolii, 217, 219. 
Portal system, 100. 
Preserving material, 12, 13. 
Proteids, 22, 23, 24, 36; use of, 38, 
102. 
Protoplasm, 14. 
Proximate principles, 35. 
Pulmonary, circulation, 127 ; ves- 
sels, 116. 
Pulse, 119. 
Pupil, 248. 
Pus, 108. 
Quack doctors, 244. 
Quarantine, 274. 
Radius, 192, 193, 194. 
Recti muscles, 246. 
Reflex action, 228, 229. 
Respiration, 140. 
Respiratory system, 132-150. 
Respired air, 156. 
Retina, 247, 248. 
Ribs, 193. 207. 
Rickets, 199. 
Ringworm, 48. 
Sacrum, 191. 
Saliva, 26, 90, 91, 92, 93. 
Salivary glands, 86. 
Salt, 22, 36. 
Salts, 29. 
Sanatoria, 289; for tuberculosis, 199. 
Saponification, 25. 
Scapula, 193, 194. 
Scarlet fever, 62, 64, 264, 275, 277. 
Sciatic nerve, 214, 222. 
Sclerotic coat, 247. 
Scrofula, 49, 266. 
Sebaceous glands, 182. 
Seeing, 250. 
Semicircular canals, 241, 242. 
Semilunar valves, 117, 118. 
Sense organs, 237-258 ; of cold, 238 , 
of hearing, 211; of heat, 238; of 
pain, 239; of pressure, 238; of 
sight, 246; of smell, 239; of taste, 
240. 
Senses of skin, 238. 
Sensory nerves, 220. 
Serous membrane, 76. 
Serum of blood, 110. 
Sesamoid bones, 194. 
Sewage, 13, 279. 
Sickness, cause of, 49-51, 260-262, 
from milk, 54, 62-65 ; prevention, 
of, 272-293. 
Sick room, care of, 274, 275. 
Skeleton, 191-194. 
Skim milk, 56. 
Skin, structure of, 178, 238; use of, 
180. 
Skull, 191-193. 
Sleep, 233. 
Sleeping sickness, 264, 269. 
Smallpox, 264, 277, 282; deaths 
from, 11, 287 ; prevention of, 286- 
288. 
Smell, 239. 
Snake bite, 300. 
Soothing sirups, 72. 
Souring of milk, 58. 
Spasms, 295. 
Spectacles, 251, 252. 
Spinal column, 77, 192. 
Spinal cord, 77, 214, 216, 219, 227- 
229. 
Spinal nerves, 214, 220, 222. 
Spittoons and health, 285. 
Spleen, 88, 112. 
Spores, 47, 49. 
Sprain, 200, 201. 
Sputum, 263, 273, 274, 285. 
Starch, 24, 26, 36; use of, 38. 
Stimulants, 37, 68-75. 
Stings, 300. 
Stomach, 82-84, 87; movements of, 
93, 94. 
Strain, 200, 201. 
Suffocation, 297. 
Sugars, 24, 26; use of, 38. 
Sunstroke, 296. 
Sweat, 182; glands of, 179, 181, 238. 
Sweeping and dusting, 160. 
Sweetbreads, 88. 320 
INDEX 
Sympathetic nerves, 215, 222, 223, 
228. 
Synovial fluid, 202; membrane, 
200. 
Systemic circulation, 127. 
Systems, 20. 
Tallow, 24. 
Tarsals, 192. 
Tarsus, 194. 
Taste, 91, 240. 
Tea, 73. 
Tears, 253. 
Teeth, 78-82. 
Temperature and health, 160. 
Temporal bone, 192. 
Tendons, 203, 207. 
Thoracic cavity, 76. 
Thoracic duct, 99, 100, 125. 
Thyroid gland, 112. 
Tissues, 19. 
Tobacco, 68-71, 75; effect on bones, 
201; on digestion, 92 ; on muscles, 
211; on nerves, 233, 234; on res- 
piratory organs, 147, 148; on 
sense organs, 256, 257. 
Tongue, 91, 134. 
Tonsil, 83, 134. 
Tonsilitis, 83. 
Touch, 238. 
Trachea, 20, 137. 
Trichinosis, 264, 267, 269. 
Tuberculosis, 11, 50, 63-65; bulle- 
tins on, 13; deaths from, 272, 
282; decrease in deaths from, 12; 
disease of, 146, 161, 169, 199, 265. 
266 ; germs of, 281; prevention of. 
208, 264-266, 278, 282-285 ; symp- 
toms of, 284; treatment of, 58, 
284. 
Tumors, 187. 
Typhoid fever, 12, 62, 63, 64, 264, 
272; cause of, 267, 268, 277; pre- 
vention, 276, 278, 279. 
Ureter, 176. 
Vaccination, 286-288. 
Vaccines, 282. 
Valves of heart, 116. 
Veins, 122. 
Vena cava, 116. 
Ventilation, 156-164. 
Villi, 97, 98, 99. 
Vocal cords, 134, 135. 
Voice, 135, 136. 
Warts, 186. 
Water, disease from, 276, 277 ; filtra- 
tion of, 278; germs in, 15, 266- 
268; need of, 12, 22, 50. 
Whisky, 72. 
White blood corpuscles, 107, 280, 
281. 
White swelling, 199, 266. 
Whooping cough, 264. 
Wine, 96. 
Wrist, bones of, 194. 
Yellow fever, 264, 269.