From the collection of the
San Francisco, California
fh <s book
A CLEAN BARN
WHOLESOME MILK MEANS CLEAN MILK
FRANK OVERTON, A.M., M.D.
AUTHOR OF "APPLIED PHYSIOLOGY"
NEW YORK STATE DEPARTMENT OF HEALTH
NEW YORK. r-CINCINNATL:. CHICAGO
AMERICAN BOOK COMPANY
COPYRIGHT, 1913, BY
COPYRIGHT, 1913, IN GREAT BRITAIN.
OVERTON, GENERAL HYGIENE.
. P. 31
THE personal welfare of each individual depends
largely on the efficiency of his bodily machinery.
The effects of mental and moral habits on the
health of the body have long been known, but the
recognition of the effects of bodily health upon
the mind and the moral character is of recent date.
Bodily health is readily within the control of either
the individual himself or his parents. The modern
science of hygiene and sanitation is founded upon
the idea of personal responsibility of each individual
for both the transmission and the acquisition of
The experiences of sailors and of explorers in un-
inhabited lands prove that a small number of healthy
persons, separated from the rest of their fellows, and
moving from place to place, will be remarkably free
from diseases and infirmities in spite of hardships
and exposure. The preservation of the same degree
of healthfulness in the midst of crowded communi-
ties is one of the greatest problems of modern life ;
and it will be solved only when every person ac-
quires a knowledge of the elementary principles of
modern hygiene and sanitation.
This is a textbook on the general subjects of
hygiene and sanitation. It is adapted for pupils in
the intermediate grades. It fulfills the require-
ments of modern courses of study in physiology,
and also conforms to the laws of the states requiring
instruction in sanitation and in the prevention of
diseases. It is also a textbook on anatomy and
physiology, but all the topics discussed have a
practical application to everyday living. The sub-
jects are presented from the point of view of a
health officer on active duty among all classes of
people, rather than that of a science teacher whose
activities are confined to a classroom.
One reason why a knowledge of hygiene is not
more widespread is that its literature is usually full
of technical terms and scientific phrases that are
not intelligible to untrained minds. This book is
not a vocabulary of new terms which must be
mastered before a knowledge of hygiene may be
acquired; but it employs everyday words and un-
derstandable English to inspire the reader to live
healthfully and to promote the cause of public
I. THE STUDY OF HYGIENE 9
II. ORGANS AND CELLS 18
III. COMPOSITION OF THE BODY 28
IV. BACTERIA 35
V. ALCOHOL 46
VI. NARCOTICS 58
VII. BONES AND JOINTS 64
VIII. MUSCLES 76
IX. CIRCULATION OF BLOOD 88
X. EMERGENCIES . .106
XI. RESPIRATION 116
XII. HINDRANCES TO BREATHING 125
XIII. FOUL Am 134
XIV. VENTILATION 144
XV. BODY HEAT 152
XVI. THE SKIN . . . . . . . . .162
XVII. EXCRETION 173
XVIII. WATER SUPPLY 184
XIX. VERMIN . .197
XX. FOOD ELEMENTS 211
XXI. DIGESTION 222
XXII. ABSORPTION AND ASSIMILATION 231
XXIII. FOODSTUFFS 238
XXIV. WHOLESOME FOOD 251
XXV. CARE OF THE NOSE AND MOUTH .... 263
XXVI. INFECTIOUS DISEASES 270
XXVII. PREVENTION OF INFECTIOUS DISEASES . . .282
XXVIII. TUBERCULOSIS 297
XXIX. THE NERVOUS SYSTEM 307
XXX. THE BRAIN ........ 318
XXXI. THE SENSES 337
XXXII. THE EYE . 346
XXXIII. THE VOICE 357
XXXIV. PUBLIC HEALTH AGENCIES 361
THE STUDY OF HYGIENE
Body and Mind. The body is a living machine,
and the mind is the engineer that controls it. The
body is useless without the mind, and the mind can
do nothing except by means of the body. The two
must work together. When either one is out of order,
the other also suffers.
One of the greatest of all the differences between
a man and a tree is that a man has a mind, and a
tree has none. A tree grows in the way in which the
soil, the weather, and other trees compel it to grow.
But a man can use his mind to choose his home, his
food, the air which he breathes, and the work which he
does. He can avoid those things which will harm his
body, and can do those things which will keep it strong
and sound. If the body is in good order, we say that it
10 THE STUDY OF HYGIENE
The Joy of Health and Strength. The mind
takes delight in directing the actions of a sound body.
A healthy boy runs for the fun of running fast, and
climbs hills and trees for the pleasure of using his
strength. He studies difficult lessons for the joy of
thinking, and puts his whole mind to a puzzle for the
delight of solving it. He has no pains or other un-
comfortable feelings, and he performs all his actions
so smoothly and easily that he almost forgets that he
has a body.
Most boys and girls do not always feel bright and
active, but sometimes they have aches and pains in
their bodies, and are too weak to work or play or
think. When they feel like this, they are either over-
tired or sick.
Is Sickness Necessary ? Men used to think that
sickness was necessary. They supposed that diseases
were caused by mighty powers in the air or ground,
just as storms and earthquakes were caused. They
thought that sickness could no more be prevented than
rainy days. Now we know that sickness is not often
caused by those things which are naturally found in
the air or ground. Most forms of sickness come from
causes which may readily be prevented, such as dirt,
spoiled food, foul air, and wrong eating. A school
child can understand how the common forms of sick-
ness are caused, and how they may be prevented.
Progress in Health Matters. In the United States
there are always over a million persons who are sick.
THE STUDY OF HYGIENE II
About two hundred thousand doctors are occupied in
caring for them. The expenses of the sickness and the
value of the time lost by the sick are at least a billion
dollars a year. But no one can estimate the suffering
and anxiety which are borne by the sick and their
There is not so much sickness among civilized nations
now as there was in former days. We know this from
a study of the records of deaths, and from the history
1. The death rate of a country is the number of
persons dying each year in every thousand inhabitants.
The governments of all civilized lands have long been
keeping records of all persons who die in those countries,
Before the year 1800, about fifty or sixty persons died
each year in every thousand inhabitants of England,
Germany, and the United States. Now, only sixteen or
eighteen persons die in every thousand inhabitants.
But in India the death rate is now as high as it was in
England a century ago. This is because the people of
India are as ignorant of health matters now as the
people of England were a century ago.
2. The average age at which persons die in civilized
lands is now nearly double the average age at which
they died a century ago. The tombs and mummies of
ancient Egypt show that the Egyptians died at an
average age of about twenty-two years. In the city
of Geneva, Switzerland, the average age of persons dy-
ing in the year 1600 was twenty-one years; in 1700,
12 THE STUDY OF HYGIENE
thirty-two years; in 1800, thirty-eight years. Now,
the average age of those dying in Geneva is over forty-
five years. This is about the average age at which
persons die in the United States, England, and Ger-
many. But in India and Russia the average age at
death is now about twenty-five years, or about the
same as it was in ancient Egypt. The people of
those countries which are the most advanced in civi-
lization and knowledge live about twice as long as the
people of the less civilized lands.
3. A disease which spreads through a whole town
or country is called an epidemic or pestilence. The
people of olden times were always in fear of war and
pestilence. Thousands of men were killed each year
by useless and cruel wars, but millions of men, women,
and children were killed by diseases which are now
seldom seen. In England in the fourteenth century,
half of the population died from the plague in a single
year. One hundred and two English colonists landed
at Plymouth, Massachusetts, in December, 1620, and
before the next spring fifty-two of them had died from
what is supposed to have been typhus fever. In 1879
one tenth of the inhabitants of the Philippine Islands
died from cholera. The plague, typhus fever, and
cholera are now almost unknown among civilized
people, but these diseases still go on in India and other
half -civilized lands. Now and then a few cases reach
the United States, but the diseases do not spread
because great care is taken to check them.
THE STUDY OF HYGIENE 13
Cause of Epidemics. - The great epidemics of olden
times were spread in very simple ways, and could easily
have been prevented. The plague was spread by rats
and fleas which swarmed over the thatched roofs and
mud floors of the huts of the people. About the year
1900 rats from foreign countries brought the plague to
San Francisco, but the disease was stopped by making
the foundations and cellars of the buildings rat proof,
so that the animals could not find hiding places.
Typhus fever spreads among people who are over-
crowded. The colonists of Plymouth were badly over-
crowded both on their ship and in their houses. They
had no proper means of bathing and no way of separat-
ing the sick from the well. To-day, there is hardly a
place in the United States where people have to live in
the way the colonists lived, and therefore typhus fever
is almost unknown in this country.
Cholera is spread principally among those who drink
impure water. In 1832 an epidemic of cholera broke
out in New York, and all the people who could get away
from the city left it in terror. At that time the drink-
ing water was drawn from wells which were dug along
the edges of the streets, and the water was foul from
slops and garbage which were thrown upon the ground.
The people were made sick by drinking house slops and
sewage. In 1840 pure water was brought to the city
through the Croton aqueduct, and since that time the
people of New York have not been in real danger of
14 THE STUDY OF HYGIENE
These examples are given to show the simple nature
of the causes of most diseases, and how they are in our
control. It is not nice to have rats in our houses ; it
is not fashionable to be dirty ; and we are ashamed to
have a bad odor about our clothes or houses. But the
feelings which educated persons have about dirt and
bad odors are not founded merely upon style and show.
Failure to keep rats and other vermin out of our houses,
and failure to keep clean, would mean sickness and death
now, just as in olden times. You may prevent a great
deal of sickness by doing the simple things which every
polite and thoughtful person in a modern town is ex-
pected to do.
Diseases of the Present. Leprosy, plague, typhus
fever, and smallpox were formerly extremely common
in all civilized lands. Now, they are seldom seen.
Yellow fever and malaria have been wiped out of Pan-
ama simply by exterminating the mosquitoes from the
place. But a great deal still remains to be done. Only
about one third of all deaths in the United States are
due to old age, and over half are caused by diseases
which may easily be prevented. Typhoid fever is
still a common disease, and what we call colds are ex-
tremely common. Consumption is now so common
that it is called the great white plague, and one tenth of
all deaths among white races is due to it. We think it
is a terrible thing that one tenth of the people of the
Philippine Islands should have died from cholera in
1879, and yet one person in every ten who now live in
THE STUDY OF HYGIENE 15
the United States will die from consumption, unless a
great deal more is done in the near future than in the
past to prevent the disease.
Helping Each Other to Keep Well. You cannot keep
well by thinking of yourself alone. You must think of
the health of others in order to protect your own health.
If you allow some one to catch tonsillitis from you, he
may give the disease to a third person, who may give
the disease back to you a month or two after you re-
cover from your first sickness.
You will often be soiled with dust from streets over
which diseased persons and animals have scattered
the germs of sickness. You will often breathe air which
the sick have breathed, and will often buy food which
has been handled by unhealthy persons. What others
do will affect your own health, and what you do will
affect the health of other persons. You are only one
among thousands of the inhabitants of a town, but the
healthfulness of your town will depend on what each
separate inhabitant does. When you help others to
keep well, you also help yourself to be healthy.
Teaching the Care of Health. A little child learns
a great deal about the care of his body from his parents.
When he goes to school, he learns more about its care
from his teachers, and from the books which he studies.
Later in life he learns from the advice of doctors, from
public lectures, and from articles in books, newspapers,
Public schools are among the best of all means for
16 THE STUDY OF HYGIENE
teaching the preservation of health. Most states now
have laws that every public school shall teach its pupils
how to take care of their bodies, and how to prevent dis-
eases. If all boys and girls will learn to do their part
in the promotion of health, the next generation of men
and women will be a vigorous, happy race. Colds /
and consumption will be as rare as leprosy is now. All
will live to a ripe old age, and sickness and pain will
be almost unknown. No one will feel that life is a bur-
den, but all will feel the joy that comes from health
and strength (p. 10).
Hygiene. The study of keeping the body in good
health is called hygiene. In it you will study such
subjects as bathing, eating, drinking, clothing, breath-
ing, exercise, and sleep.
Hygiene also includes the study of the methods and
conditions by which diseases are prevented. It there-
fore treats of such subjects as the purity of food, the
wholesomeness of drinking water, the freshness of the
air, and the disposal of sewage.
Anatomy and Physiology. Before you can under-
stand the care of the body, you must know something
about the structure of its living machinery, and how it
does its work. The study of the structure of the body
is called anatomy, and the study of its work and action
is called physiology. You must study the anatomy and
physiology of each part of the body in order to under-
stand the care of that part.
THE STUDY OF HYGIENE 17
What are some of the signs of good health ?
What are some of the signs of poor health ?
What effect does sickness of the body have upon the mind ?
About how many persons in the United States are sick at one
About how much money does sickness cost the people of the
United States each year ?
Give some reasons for thinking that there is less sickness now
What is the average death rate in the United States ?
What is the average length of life in the United States ?
What is an epidemic ?
Name some epidemics which used to be common, but are now
What are some of the reasons why deadly epidemics no longer
Name some deadly diseases which are now common.
How does a person protect his own health when he helps
others to keep well ?
What is hygiene ?
What is physiology ?
What is anatomy ?
What is the object of teaching hygiene in schools ?
GEN. HYG. 2
ORGANS AND CELLS
Life and Growth. - - The food upon which the body
lives has no life, but it becomes living blood, flesh, and
bone in the body. After remaining alive for a few
days or weeks, the living flesh becomes worn out and is
changed back to dead and lifeless forms, and new flesh
is formed to take its place.
The constant building up of worn-out parts of the
body is what is called life and growth. Lifeless things
change and go to pieces, and cannot build themselves
up again. Living things are said to be alive because
they build themselves up as fast as they wear out.
Voluntary and Involuntary Actions. A person can
use his mind in thinking, and his body in moving, when-
ever he wishes to do so. These two kinds of work are
directed by the mind, and are called voluntary actions.
The actions of growth and repair are only slightly
under the control of the mind, and are called involuntary
actions. These actions go on while a person is asleep
even better than they do while he is awake. The same
kinds of action go on in a tree, which has no mind at all.
Division of Labor in the Body. Each action takes
place in a particular part of the body, and in no other
ORGANS AND CELLS
part. One part of the body thinks, another prepares
food, another supplies air to all the rest of the body,
and other parts get rid of the worn-out flesh. A part of
the body which has a particular work to do is called
Organs of Digestion. - - The act of changing food to
forms which living flesh can use is called digestion.
There are four principal
organs of digestion: i, a
bag, called the stomach,
which receives the food
when it is swallowed ; 2, a
long tube, called the intes-
tine, in which the food is
dissolved ; 3, a mass of
flesh, called the pancreas,
in which a liquid is pre-
pared for dissolving the
food ; and 4, a large mass
of flesh, called the liver, in
which the food is made a
part of the blood.
Organs of Circulation.
Blood carries digested
food through all parts of
the body, and its flow
is called the circulation.
There are two principal
Diagram of the position of the prm-
Organs of circulation: I, a cipal organs of the body.
20 ORGANS AND CELLS
pump, called the heart, which keeps the blood in
motion ; and 2, a vast number of tubes, which con-
duct the blood through all the flesh and bones.
Organs of Respiration. - - The body cannot work,
or even live, unless a constant supply of air reaches every
part. Taking air into the body, and the changes pro-
duced by the air, are called respiration. The principal
organs of respiration are the lungs.
Organs of Excretion. Getting rid of worn-out
substances is called excretion. There are two principal
organs of excretion: the kidneys and the skin. The
lungs, the liver, and the intestine are also important
organs of excretion.
Organs of the Nervous System. All the parts of the
body are made to help one another, and to work to-
gether, by means of the nervous system. There are
three principal organs of the nervous system: i, the
brain, situated in the top of the head; 2, the spinal
cord, situated in the backbone ; and 3, long strings of
flesh, called nerves, which extend from the brain and
spinal cord to all parts of the body.
Organs for Voluntary Work. - - There are two organs
for doing voluntary work: i, the brain, which does the
work of thinking ; 2, a large number of bundles of lean
meat, called muscles, which produce motions. Stiff
rods and plates, called bones, support the soft flesh and
assist the muscles to produce nearly all the voluntary
movement of the body.
Cells. An organ is not like a lump of clay which is
ORGANS AND CELLS
the same throughout its
whole mass r but it is made
up of microscopic living
things called cells. All flesh
is composed of cells which
do their work like separate
Cells in Lower Animals
and Plants. All animals
and plants are composed of
cells. In the lowest forms
of living beings each animal
and plant is Composed of a Slipper animalcules. Magnified.
single cell. A common one-celled animal is called the
slipper animalcule, or paramecium. It is microscopic
in size, and is found in stagnant
Place a handful of hay or dry
grass in a jar of water, and leave
I9tjj\ the jar in a warm room. After
two or three weeks the water will
usually contain great numbers of
tiny white specks, each of which
is a paramecium. If you look at
a drop of the water with a micro-
scope, you can see the shape and
structure of the animals as they
move rapidly through the water.
Threads of pond algae. ...
Magnified Collect some of the green, silky
ORGANS AND CELLS
threads which float on still ponds, or grow on sticks
and stones in the water. These threads are green
plants called alga. Examine a few of the plants
under a microscope. Each plant is a thread which
consists of a single row of oblong cells joined end to
All higher plants and animals, such as wheat or a
bird, consist of masses of cells.
Size and Shape of Cells. - - The different kinds of
cells in the human body vary in size and shape, but not
one of them is large enough
to be seen with the naked
eye. If you scrape the skin
with a knife, you will get a
white powder which looks
like flour. This powder con-
sists of cells from the outer
covering of the skin. If you
look at the powder with a
microscope, the separate cells
appear like flat scales. The
largest of these cells measure
about one five-hundredth of
an inch across.
A muscle cell is shaped like a string, and is about
one five-hundredth of an inch in diameter and about one
fiftieth of an inch in length. A blood cell is round and
almost flat, and measures about one three-thousandth
of an inch across. If you put a bit of flesh under a micro-
Cells scraped from the back of
the hand. Magnified,.
ORGANS AND CELLS
Cells of epithelium from the
scope, you can tell from what organ it came by noticing
the size, shape, and arrangement of its cells.
How Cells Grow. Most of
the cells of a baby*s body are
of the same size and shape as
the cells of a grown man, but
there are not so many of them.
A child does not grow by mak-
ing the cells of its body larger,
but by making their number
A cell consists of two parts:
i, a soft jellylike substance, which forms the greater
part of the cell; and 2, a darker bit
of matter, called the nucleus, which
is situated near the center of the cell.
When a cell reaches full size, its nu-
cleus divides into two parts, and the
rest of the cell then splits itself in
half between 'the halves of the nu-
cleus. Thus a young cell is just half
the size of a full-grown cell, but it is
like a full-grown cell in all other re-
Connective Tissue. A group of
cells which look and act alike is
called a tissue. The working cells of
every organ are held in place by a tissue called con-
nective tissue. These cells are small, and have long,
ORGANS AND CELLS
slender arms which are tough and strong. These arms
extend around and between the cells, and hold them in
place. If you examine the
end of a piece of beefsteak,
you will find a white net-
work of tough connective
tissue lying between red
bundles of soft muscle cells.
Some connective tissue is
found in every part of the
body. It forms the greater
part of the skin.
Epithelial Tissue. The
whole skin is covered with
cells which are like soft
scales. These cells are called
epithelial tissue, or epithe-
lium. One of their principal uses is to protect the
soft and delicate flesh under them.
Glands. - The skin is always moist with a liquid,
called the sweat, or perspiration. The sweat comes
from pores, which are the openings of deep, narrow tubes
extending into the skin. Each tube is lined with cells
of epithelium, which extend down the tube from the
surface of the skin. The use of the cells of epithelium
inthe tube is to form the sweat or perspiration out of
material brought to them by the blood.
A tube composed of cells of epithelium, which form
a substance out of the blood, is called a gland. The
Beefsteak. Connective tissue
around bundles of muscle cells.
ORGANS AND CELLS 25
substance which a gland forms is called a secretion.
Sweat glands are found in the skin on nearly every part
of the body.
The kidneys, liver, and
pancreas are glands. They
are composed of tubes of epi-