NEW-WORLD HEALTH SERIES 
BOOKS II AND III / 
PRIMER OF 
SANITATION AND 
PHYSIOLOGY 
BEING PRIMER OF SANITATION AND 
PRIMER OF PHYSIOLOGY IN 
ONE VOLUME 
BY 
JOHN W. RITCHIE 
IrOlTOR OF NEW-WORLD SCIENCE SERIES; JOINT AUTHOR OF 
NEW-WORLD HEALTH SERIES 
Illustrated by 
KARL HASSMAN 
HERMANN HEYER 
EARL HORTER 
HARRY FREEMAN 
1920 REVISION 
YONKERS-ON-HUDSON, NEW YORK 
WORLD BOOK COMPANY WORLD BOOK COMPANY 
THE HOUSE OF APPLIED KNOWLEDGE 
Established 1905 by Caspar W. Hodgson 
Yonkers-on-Hudson, New York 
2126 Prairie Avenue, Chicago 
“Our national health is physically our great- 
est asset. To prevent any possible deteri- 
oration of the American stock should be a 
national ambition.” These words of Theo- 
dore Roosevelt express the idea that has 
actuated authors and publisher of New- 
World Health Series. The texts explain 
the means by which young Americans can 
lay the foundations for sane and vigorous 
lives. They stand preeminent among Books 
That Apply the World’s Knowledge to the 
World’s Needs. This particular volume, 
which combines the second and third books 
of the series, teaches the essentials of sani- 
tation and physiology. The conservation 
of individual and national health is the pur- 
pose of the series 
Copyright 1909, 1913, 1915, 1920, 1923, by World Book Company 
Copyright in Great Britain 
. All rights reserved 
NWHS: RP OF SP-29 
PRINTED IN U.S.A. PREFACE 
“What you would have appear in the life of the people, 
that you must put into the schools,” is the substance of the 
advice given by a famous educator to his countrymen. The 
soundness of this advice has never been questioned, and the 
experience of the writer of this book has brought the conviction 
that in sanitary matters it can be applied with absolute literal- 
ness,— that our country can hope to shake off completely and 
permanently its burden of preventable disease only when the 
public schools give adequate instruction in the principles of 
preventive medicine and in the possibilities of public hygiene. 
The author has therefore followed with sympathy and very 
great interest the efforts that are being made to teach sanitation 
in the public schools, and has felt that the effectiveness of these 
efforts would be very greatly increased if they were supple- 
mented by an elementary text-book in this field. With this in 
mind he has tried to write down in a simple manner, and in a 
form suitable for school use, the more important facts in regard 
to germ diseases and their prevention. The public side of the 
question has been given considerable space, because the rela- 
tion of the government to the health of its citizens is an impor- 
tant and an intimate one, and because we seem destined to 
come into a realization of civic obligation largely through 
public sanitation. 
In presenting the subject of physiology, the author has 
attempted to give the pupil a general idea of the plan and 
working of his body ; to make plain to him the possibilities of 
health; and to point out the paths that lead to the realization 
of these possibilities. 
The author believes that hygiene is best taught by giving 
a solid basis of structure and function for it. He has little 
confidence in get-wise-quick methods in any subject, and he 
has not hesitated to include sufficient physiology, with the 
anatomy that is needed to make it intelligible, to give an 
outline knowledge of the human mechanism. At the same 
III IV 
PREFACE 
time, the attempt has been made to select for treatment, from 
the vast field of physiology, topics that have direct and vital 
hygienic applications, — to teach hygiene through the modern 
physiology that lies behind it, rather than to teach hygiene by 
rule-of-thumb methods or to teach physiology for its own sake. 
It has been thought best at times to go somewhat far afield 
with the hope of widening the pupil’s hygienic horizon; for the 
world is filled with people who for lack of a few large ideas are 
unable to use the many small ones that they have accumulated. 
With the idea that children ought not to be taught the matter 
that is in a book of this kind because it may bring into their 
minds thoughts of sickness, the author is, of course, not in 
agreement. The real and vivid ideas of disease that are in the 
minds of children come not from books, but from personal ex- 
perience on beds of sickness; from first-hand knowledge of the 
suffering of disease-stricken parents, brothers, and sisters ; and 
from the sudden vanishing of playmates and friends. As long 
as disease is in the lives of children, it will be in their minds, 
and the way to put it out of their minds is to banish it from 
their lives. The author has done his part in writing this book 
with the hope that it would do something to bring sunshine 
and happiness into the lives of the children that now are and 
are yet to be. He believes that modern hygienic knowledge 
is able to free our people from most of their illnesses, and that 
this knowledge ought to be given to the people by the schools 
that have been founded for their instruction. CONTENTS 
PART I. PRIMER OF SANITATION 
CHAPTER PAGE 
1. Why the Study of Disease Germs is Important i 
II. The Cells of the Body 3 
III. Disease Germs and how they get into the Body 6 
IV. The Struggle between the Body and the Germs ii 
V. Bacteria 18 
VI. The Skin 21 
VII. The Pus-forming Bacteria 24 
VIII. Tetanus (Lockjaw) 29 
IX. The Air Passages and the Lungs 33 
X. Diphtheria 36 
XI. Pneumonia 42 
XII. Influenza, Whooping Cough, and Colds . . 47 
XIII. Tuberculosis 53 
XIV. The Treatment of Consumption . . . .61 
XV. Dust and Germ Diseases 71 
XVI. Bacterial Diseases of the Intestine ... 76 
XVII. Typhoid Fever 77 
XVIII. Diseases caused by Relatives of Typhoid Germ . 81 
XIX. Other Bacterial Diseases of the Intestines . 83 
XX. Disease Germs in Water 86 
XXI. Other Bacterial Diseases 95 
XXII. Protozoa 101 
XXIII. Malarial Fever and Yellow Fever . . . 103 
XXIV. Mosquitoes no 
XXV. Smallpox 117 
XXVI. Other Germ Diseases 128 
XXVII. Intestinal Worms 135 
XXVIII. The Importance of Sanitation . . . .141 
XXIX. The Housefly 145' 
XXX. Disease Germs in Food 151 
XXXI. Disinfection 158 
XXXII. Unhygienic Habits 164 
XXXIII. Public Sanitation 171 
XXXIV. Governments and the Public Health . . . 177 
V VI 
CONTENTS 
CHAPTER PAGE 
XXXV. Practical Sanitation 187 
XXXVI. A New Kind of Disease Germ . . . .194 
XXXVII. New Discoveries in Regard to Germ Diseases . 200 
' PART II. PRIMER OF PHYSIOLOGY 
I. The Possibilities of Good Health . . . .213 
II. The Human Body and the Cells of which it is Built 219 
III. The Framework of the Body . . . . .228 
TV. The Muscles and the Carriage of the Body . 238 
V. The Heart and the Circulation of the Blood . 251 
VI. Respiration 265 
VII. Ventilation 272 
VIII. Adenoids and Colds 282 
IX. Clothing and the Body Heat 295 
X. The Nervous System 303 
XI. The Care of the Nervous System . . . .314 
XII. The Eye 321 
XIII. The Ear 334 
XIV. The Organs of Touch, Taste, and Smell . . 341 
XV. Foods and why we Need Them .... 347 
XVI. The Digestive Organs and their Work . . 357 
XVII. The Foods within the Body 370 
XVIII. Foods and Health 378 
XIX. The Teeth 394 
XX. Tobacco . . 409 
XXI. Alcohol 422 
XXII. Accidents 434 
XXIII. Realizing Health Possibilities 446 
XXIV. Further Facts concerning Health . . . 455 
XXV. Vitamins 472 
Appendix 479 
Pronouncing Glossary 485 
Index 487 PART I 
PRIMER OF SANITATION CHAPTER ONE 
WHY THE STUDY OF DISEASE GERMS IS IMPORTANT 
Suppose that in a happy and healthful village a 
strange plant should suddenly spring up and give off 
poisonous matter into the air. Suppose that every one 
who passed by it became ill, and that all the people who 
lived near it died because of the deadly gases from the 
plant. Would the people of the village allow that plant 
to ripen its seeds and scatter them abroad so that in a 
short time plants of the same kind would be growing 
along all the streets and in all the dooryards ? Or 
would the people cut down the plant and destroy it root 
and branch ? 
Suppose that poisonous serpents should appear in a 
town and should attack the people. Would the inhabit- 
ants of that town allow the serpents to live and multiply 
in the streets and about their houses? Or would they 
hunt out and kill the reptiles that were doing them so 
much injury ? 
The people would certainly destroy both the deadly 
plant and the poisonous serpents, for no one would wish 
to suffer illness or death because of them. 
Poisonous plants like the one described above do not 
exist, and, in most parts of the world, dangerous serpents 
are very rare. But in all the earth there is not a town 
or a village where there are not great numbers of very 
small plants and animals that attack the people and 
cause many of them to become sick and die. These 
small plants and animals are called disease germs, and 
they cause many of the worst diseases that afflict man- 
kind. 
1 2 
PRIMER OF SANITATION 
In a country where dangerous wild animals are found, 
the inhabitants know when they are safe and when they 
must be on their guard; they know that their enemies 
lurk only in certain places, and by avoiding these places 
they are usually able to live in security and peace. But 
a stranger in such a land often imagines that monsters 
are everywhere waiting for him; even when he is far 
from danger he is beset with constant fears ; and in spite 
of all his care he is likely to walk straight into the midst 
of his foes. 
So a person who understands about disease germs gives 
little thought to them, because he knows when he is safe 
and how and when to guard himself from them. But per- 
sons who do not understand about germs often foolishly 
imagine that the world is full of them; they live in con- 
stant fear and make many useless efforts to guard them- 
selves from them ; and then in some simple manner they 
allow the germs to get to them. 
In this book we shall study about disease germs and 
how to avoid them. It is important for you to under- 
stand this subject; for a knowledge of it will often 
enable you to protect yourself from germs; it will allow 
your mind to be at peace when there is no danger from 
them; and it will help you to do your part in hastening 
the time when there will be no more disease germs in 
our land. 
POINTS TO BE REMEMBERED 
1. Everywhere very small plants and animals called disease 
germs are attacking people and causing sickness. 
2. It is important for you to understand about disease germs 
in order to know how to escape them and avoid being 
frightened when there is no danger from them. CHAPTER TWO 
THE CELLS OF THE BODY 
As a house is built of bricks and a heap of sand is 
composed of a multitude of small grains, so is the human 
body made up of a great number of very small parts 
called cells. These cells are so small that we cannot 
Fig. 1. When we look at a house 
from a distance we cannot see the 
bricks in the walls. 
Fig. 2. But when we stand close to 
the house, we can easily see the 
bricks of which it is built. 
see them without a microscope, but if you could examine 
a small piece of skin or other part of the body under a 
microscope, you could very easily see the cells of which 
it is composed. The skin, the muscles, the liver, the 
stomach, the brain, and all the other body parts are 
built of these little cells.1 
The cells are alive. Each one of the little cells of the 
body is alive. Each one takes in food and grows, and 
does all those things that make a living being different 
from sticks and stones and other things that are not 
1 The cells of the body are exceedingly small. So small are they that it 
would take about 2500 of them placed side by side to make a row an inch 
long. There are 5,000,000 cells in a very small drop of blood, and accord- 
ing to one estimate, 400,000,000,000 cells in the average human body. 
3 4 
PRIMER OF SANITATION 
alive. When the cells are in health, the body is in 
health; and when the cells are dead, the body is dead; 
for the life of the body is in the cells of which it is built. 
Fig. 3. When we look at the body, we cannot see the cells of which it is made, 
But with a microscope the cells of the body are easily seen. 
Keeping our bodies in health. Certain things are 
necessary to the cells of the body. They must have 
food, they must have oxygen from the air, they must get 
rid of their poisonous wastes, and they must have a con- 
stant temperature, neither too hot nor too cold. If our 
cells do not have all these things, they will die. They 
may be killed in other ways, too, as by being crushed, 
by electricity, and by poisons. To keep our bodies in 
health, therefore, we must supply our cells with the 
things that they need and we must keep poisons and 
other injurious substances away from them. 
Disease germs. Our bodies are very wonderful ma- 
chines, but sooner or later sickness comes to most of 
us. Sometimes the stomach and other digestive organs 
fail to work properly, and then the cells suffer from a THE CELLS OF THE BODY 
5 
lack of food. Sometimes the heart and blood vessels 
become diseased, and then the blood fails to circulate 
through the body as it should. Sometimes the kidneys 
fail in their work, and then the cells are injured by 
poisonous wastes. But the most common of all causes 
Fig. 4. A is a single cell as it appears 
under the microscope. B is a cell drawn 
to show that it has length, breadth, and thick- 
ness. C is a group of cells, showing how 
they are built together in the body. 
FIG. 5. A section of the 
outer layer of the skin, as it 
appears under a microscope. 
The outer cells die and fall off 
as dry scales. 
of sickness is that disease germs get into the body and 
poison the cells. In the next chapter we shall learn 
more about these small germs and how they cause 
disease. 
POINTS TO BE REMEMBERED 
1. The human body is built of very small cells. 
2. The cells are alive. 
3. When the cells are in health, the body is in health, and 
when all the cells are dead, the body is dead. 
4. The cells must have food and oxygen, and they must not 
be poisoned or injured in other ways, or they will die. 
5. Disease germs cause sickness by poisoning the cells. CHAPTER THREE 
DISEASE GERMS AND HOW THEY GET INTO THE BODY 
Disease germs are the greatest enemies of mankind. 
Every day they kill thousands of people, and they cause 
the loss of an untold amount of time and money. To 
get an idea of the amount of sickness, sorrow, and loss 
that is caused by these small creatures, imagine a land 
where no colds, catarrh, consumption, influenza (grip), 
diphtheria, or pneumonia ever come; a land where 
boils, blood poisoning, and tetanus (lockjaw) are un- 
known ; where there is no smallpox, measles, scarlet 
fever, whooping cough, or mumps; a land without 
malaria, cholera, leprosy, yellow fever, or plague; a 
land free from typhoid fever, and from many of the 
other diseases that afflict mankind. Picture to yourself 
a country and a people free from all these diseases, a 
country where many of the inhabitants pass from child- 
hood to old age without sickness or disease, and you 
will have an idea of what a land without disease germs 
would be like.1 
What disease germs are. In water and in the soil 
there are millions of little plants and animals — plants 
and animals so small that they can be seen only with a 
powerful microscope. The body of one of these little 
plants or animals is composed of a single cell. The 
little one-celled plants are called bacteria (singular, 
bacterium). The little one-celled animals are called 
protozoa (singular, protozoon). Disease germs are bac- 
teria and protozoa that grow in the body and poiso?i 
the cells. 
1 It is within the power of man to cause all parasitic diseases to dis- 
appear from the world. — Pasteur. 
6 DISEASE GERMS 
7 
Where disease germs come from. At this point you 
should get it firmly fixed in your mind that disease 
germs are living plants and animals; and that just 
as a pine tree can come only from the seed of a pine 
FIG. 6. The great outdoor world is practically free from germs. 
tree, or as a chicken can come only from the egg of 
a chicken, so a disease germ can come only from an- 
other germ of the same kind. It is a common idea 
that germs spring from unclean and decaying matter — 8 
PRIMER OF SANITATION 
that “ filth breeds disease germs ” — but this idea is 
not correct. They are often found in unclean matter, 
and such matter is dangerous because germs may re- 
main alive in it for a long time. But germs can no 
more originate in such matter than a cow can come from 
the grass in the pasture, or a stalk of corn can spring 
up where no grain of corn has been planted in the 
earth. Nearly all the germs that attack us are spread 
from the bodies of persons who are sick with germ 
diseases. 
The world not swarming with disease germs. From 
the very beginning of your study of this subject you 
should clearly understand that the world is not filled 
with disease germs that are lying in wait to attack 
us. It is true that bacteria and protozoa are abun- 
dant in water, that bacteria are swarming in the soil, 
and that they are constantly being blown about in the 
air. But of all the many hundreds of kinds of bac- 
teria and protozoa that are in the world, only a few 
cause disease. The others are harmless, and even when 
they get into our bodies, it is not we, but the bac- 
teria and protozoa, that suffer. The germs of most 
diseases quickly die outside the human body. It is 
a mistake to think that every breath of air is dan- 
gerous, and that all food and water contain disease 
germs. The winds that blow over the meadows, the 
rain that falls from the clouds, the trees of the forest, 
the grass in the pasture, and, in general, the great out- 
door world, are practically free from germs. In the 
bodies of persons who are sick from germ diseases, 
in the houses where sick people live, and wherever 
the wastes from the bodies of the sick go, there, and DISEASE GERMS 
9 
in most cases there only, are disease germs to be 
found. 
The first great rule for the prevention of germ dis- 
eases. The first great rule for the prevention of germ 
diseases is : destroy the germs that come from the bodies 
of the sick. If all the diph- 
theria germs that come from 
human throats could be de- 
stroyed, there would soon be 
no more diphtheria. If all 
smallpox germs that come 
from the bodies of persons 
who have the disease could 
be destroyed, there would 
soon be no more smallpox. 
It is easier to destroy germs 
as they come from the bodies 
of the sick than it is to de- 
stroy them after they have 
been spread abroad, and a little intelligent care used in 
keeping germs from being scattered would every year 
save millions of lives. 
How germs enter the body. Except in a few cases 
which we shall discuss later, germs do not pass through 
the unbroken skin, but nearly all germs that enter the 
body get into it through wounds, or through the mouth or 
nose. In later chapters we shall learn what germs get 
into the body through cuts and sores; we shall study 
about biting insects (mosquitoes, flies, ticks, fleas, and 
bedbugs) that pierce our germ-proof armor (the skin) 
and place germs directly in the wounds that they make. 
We shall read of other germs that enter the body by 
Fig. 7. The germs that attack us 
come from the bodies of the sick. 10 
PRIMER OF SANITATION- 
way of the nose, and we shall learn how very dangerous 
germs may reach the mouth from flies, from the hands, 
from drinking cups, in food and water, and in many other 
ways. Here we wish only to call your attention to the 
fact that wounds (many of them made by insects), the 
nose, and the mouth are the gateways through which 
disease germs get into the body. 
The second great rule for the prevention of germ dis- 
eases. The second rule for the prevention of germ 
diseases is : take care of wounds, protect yourself from, 
biting insects, and guard the mouth and nose. The first 
rule aims to keep disease germs from being scattered 
abroad. The second rule aims to keep out of the body 
the germs that do get scattered abroad. If we neglect 
either of these laws, we cannot hope to escape the dis- 
eases that are caused by germs. 
POINTS TO BE REMEMBERED 
1. Disease germs kill more than half the human race. 
2. Disease germs are very small plants and animals. 
3. A disease germ can spring only from another germ of the 
same kind. 
4. Nearly all the germs that attack us come from the bodies of 
sick persons. 
5. The first great rule for the prevention of germ diseases is : 
destroy the germs that come from the bodies of the sick. 
6. Germs enter the body through wounds, through the nose, 
and through the mouth. 
7. The second great rule for the prevention of germ diseases 
is : take care of wounds, protect yourself from biting insects, 
and guard the mouth and nose. CHAPTER FOUR 
THE STRUGGLE BETWEEN THE BODY AND THE GERMS 
In spite of the greatest care that we can take, all of 
us are certain at times to get disease germs into our 
bodies. Between these germs and the body there is 
then war. The germs attack the body. They try to 
grow in it and use it for food. To defend itself the 
body kills the germs. In this chapter we shall learn 
how the body resists its small foes. 
How germs cause sickness. The germs of some 
diseases (diphtheria, tetanus) produce poisons that are 
called toxins. These toxins are carried through the 
body in the blood, and cause sick- 
ness by poisoning the cells. A 
little group of tetanus germs in a 
small wound, or a small patch of 
diphtheria germs growing in the 
throat, may produce enough toxin 
to poison and kill the whole body. 
The germs of other diseases (ty- 
phoid fever, pneumonia) produce 
no free toxins ; but when the germs 
are killed and broken up, toxins 
that have been produced within 
them are set free, and the materials of which the germs 
themselves are made act as poisons to the cells. In 
these diseases the end of the illness comes when the 
germs have all been killed, but the faster they are de- 
stroyed the more severe for the time will the disease be. 
How the body destroys toxins. One way in which the 
body protects itself against germs is by producing anti- 
toxins. When disease germs grow in the body and 
Fig. 8. A shows the white 
and B the red corpuscles 
of the blood as they appear 
under a microscope. 
11 12 
PRIMER OF SANITATION 
begin to poison it with toxin, the body begins to produce 
antitoxin. The antitoxin does not kill the germs, but it 
does destroy the toxin, and thus saves the cells from being 
poisoned until in other ways the body can kill out the 
germs.1 
How the body kills germs. If you should examine a 
drop of blood with a microscope, you would find a very 
great number of cells floating in the liquid part of the 
Fig. 9. A white corpuscle taking in a bacterium. 
blood (Fig. 8). These cells are of two kinds. Most of 
them are red in color, and these are called red corpuscles. 
Their work is to carry oxygen through the body. The 
other kind of cells in the blood are the white corpuscles. 
These are the soldiers of the body, and their work is to 
kill disease germs. 
A white corpuscle approaches a germ and flows about 
it, or swallows it, as you see in Figure 9. Then the 
corpuscle tries to digest and kill the germ, while the germ 
tries to grow in the corpuscle and use it for food. When 
the corpuscles are victorious, the germs are destroyed 
and the disease is stopped. But if the germs are too 
numerous and too powerful, the corpuscles are killed, 
and the disease goes on until the body dies. 
1 There is a different toxin and antitoxin in each different germ disease. 
The toxin and antitoxin of diphtheria, for example, are different from the 
toxin and antitoxin of tetanus or of typhoid fever. STRUGGLE BETWEEN BODY AND GERMS 
13 
Besides the white corpuscles, there is another great 
defender of the body, the germicidal (“ germ-killing ”) 
substance of the blood. There is always some of this 
substance in the blood of a healthy person, and when 
disease germs attack the body, more of the germicidal 
substance appears in the blood and helps to kill 
them. In our fight against the germs this germicidal 
substance is perhaps even more important than the 
white corpuscles.1 
Why we have certain diseases only once. When germs 
attack us, the body manufactures more of its germicidal 
substances to kill them. More and more of the germi- 
cidal substance is formed, and the blood becomes stronger 
and stronger in its power to kill germs. Finally, if the 
body is successful in its struggle with its enemies, the 
germicidal substance and the white corpuscles get the 
'upper hand of the germs and recovery begins. After a 
patient recovers from some diseases (for example, small- 
pox, measles, and whooping cough), a large amount 
of germicidal substance remains in the blood for years, 
or even for life. Any germs of these diseases that get 
into the blood are therefore promptly killed, and a person 
is seldom attacked by one of these diseases more than 
once. Cases of infantile paralysis, pneumonia, small- 
pox, and many other infectious diseases are treated with 
blood from a person who has recovered from the disease. 
Why could such blood be expected to kill the germs ? 
1 The body produces different germicidal substances in killing the 
germs of different diseases, just as different toxins and antitoxins are pro- 
duced in different diseases. A person therefore may have a great power 
of killing the germs of one disease, as, for example, smallpox, and at the 
same time fall an easy victim to some other disease, as consumption. 14 
PRIMER OF SANITATION 
Keepmg up the resistance of the body to germs. 
Through all your study of germ diseases you should 
bear in mind the importance of keeping up the germi- 
cidal power of the body. All of us, without knowing it, 
Fig. io. Dry feet, fresh air, and plenty of sleep help to keep up the power of 
the body to kill germs. 
take into our bodies the germs of deadly diseases. As 
the seeds of plants lie in the cold earth waiting for the 
warmth of spring to come, so these germs often lie in 
the body waiting for a chance to grow. The only safe 
way, therefore, is to keep the body always in health, 
so that it will be able to kill any disease germs that may 
enter it. Overwork, exposure to cold," wet feet, hunger, 
fatigue, worry, lack of fresh air, lack of sleep, alcohol — 
all of these things injure the body and lower its germi- 
cidal power. It is the duty of every one to keep himself 
in health — to care for his body intelligently and care- 
fully— and to fail to do this is no more sensible than it 
would be sensible for the soldiers in a fort to open the 
gates and lie down to sleep in the midst of their enemies. 
Alcohol and resistance to germs. Experiments on ani- 
mals prove that alcohol lessens the power of the body STRUGGLE BETWEEN BODY AND GERMS 
15 
to kill germs. When alcohol is given to rabbits it is not 
possible to save them from rabies (hydrophobia) by the 
Pasteur treatment (page 129). Other experiments show 
that the germs which cause boils and blood poisoning 
are able to attack rabbits that have had alcohol more 
easily than they can attack rabbits that have had no 
alcohol. Still other experiments show that animals 
which have been given alcohol cannot resist the germs 
of cholera, tetanus (lockjaw), and other diseases so well 
as animals which have not been given alcohol. Experi- 
ments like these leave no room to doubt that alcohol 
taken into the body lessens the power of the blood to 
kill germs. 
Many physicians have long believed that this was 
true, for they have known that drinkers suffer far more 
from many germ diseases than do those who use no 
alcohol. A spell of drinking often brings on an attack 
of pneumonia, and the death rate from pneumonia is very 
high among drinkers. Consumption is also very common 
among drinkers, the records of one foreign life insurance 
company showing a consumption death rate more than 
five times as high among brewers as among Protestant 
ministers. Wounds heal less rapidly in users of alcohol 
than in abstainers, and the inflammation is more likely 
to run on into blood poisoning in a drinker. So in 
cholera and typhoid fever it is the drinkers who suffer 
most, and there is every reason to believe that this is 
the case in all germ diseases. Drink no alcohol if you 
wish to keep up the power of your body to resist germs, 
for users of alcohol are attacked by germ diseases more 
frequently than abstainers, and many of them die of 
these diseases when they are attacked. 16 
PRIMER OF SANITATION 
The third great rule for the prevention of germ diseases. 
The third great rule for the prevention of germ diseases 
is: keep the body in health, so that it will be able to kill 
disease germs. A general does not risk the fate of his 
army on a single battle line, but behind the first line of 
soldiers he places a second line, and behind the second 
line he has still a third line of defense in case the enemy 
Fto. ii. The Castle of Health. Read the three rules for the prevention ol 
germ diseases, and tell what the two outer defenses of the castle, and the walls 
of the castle itself, represent. 
should break through the first and second lines. So in 
our warfare with the germs we should not depend on 
any single line of defense. We should try to keep 
germs from being spread about, we should guard the 
gateways by which they enter the body, and within the 
body we should have the defenders at their posts. For 
sooner or later, just when we cannot tell, our unsleeping 
enemies will pass through the first and second lines of 
our defense, and if at that time the health of the body 
is low and the defenders of the body are weak, it will be 
the worse for us. 
Increasing the defenses of the body by vaccination. 
Vaccination has been employed as a protection against STRUGGLE BETWEEN BODY AND GERMS 
17 
smallpox for more than a century (page 119) and of recent 
years it has been used to increase the resistance of the 
body to the germs of rabies, boils, typhoid fever, plague, 
and of many other diseases. In vaccination, weak or 
dead germs of the kind that cause the disease are in- 
troduced into the body. This causes the body to manu- 
facture germicidal substances, or it increases the activity 
of the white corpuscles, thus providing a defense against 
the living germs that cause the disease. In later chap- 
ters we shall discuss this subject in more detail. 
POINTS TO BE REMEMBERED 
1. Dangerous germs often get into the body in spite of the 
greatest care that we can take. 
2. These germs cause disease by growing in the body and 
poisoning the cells. 
3. The body defends itself by producing antitoxins that destroy 
the toxins. 
4. The body kills germs by means of the white corpuscles and 
the germicidal substances of the blood. 
5. We have certain diseases only once because after recovery 
from these diseases the germicidal substances remain strong 
in the blood. 
6. The germicidal power of the body should not be allowed to 
run low, because disease germs may be in the body waiting for 
a chance to grow, or may get into it at times unknown to us. 
7. Alcohol lessens the power of the body to kill germs. 
8. The third great rule for the prevention of germ diseases is : 
keep the body in health, so that it will be able to kill disease 
germs. 
9. The resistance of the body to certain germs may be increased 
by vaccination. CHAPTER FIVE 
BACTERIA 
Bacteria are the smallest of all living things. Mil- 
lions of them have plenty of room to swim in a drop of 
water. Twenty-five thousand of them placed side by 
side would make a row only an inch long. Examined 
under a microscope that would cause a man to appear 
as high as Mt. Washington or Mt. Mitchell, these small 
plants look about as large as periods and commas in or- 
dinary print. So exceedingly small are they that they 
can pass through the pores of a brick as easily as a man 
can pass through the doorway of a house. 
The multiplication of bacteria. Bacteria multiply by 
simply pinching in two. Some of them can divide and 
FIG. 12. A diagram showing the way 
a bacterium multiplies by pinching in 
two. 
Fig. 13. The three shapes of 
bacteria, — cocci, bacilli, and 
.spirilla. 
become full-grown in fifteen or twenty minutes; but 
this, of course, is very rapid, even for a bacterium. 
They can easily divide once an hour, however, and at 
this rate one bacterium even in a single day can increase 
to a multitude. It is this power of rapid multiplication 
that makes disease germs dangerous to mankind. 
The shapes of bacteria. Bacteria are cylindrical, spher- 
ical, or spiral — shaped like a fire-cracker, a marble, or 
a corkscrew. The cylindrical bacteria are called bacilli 
(singular, bacillus'). The spherical bacteria are called 
18 BACTERIA 
19 
cocci (singular, coccus), and the spiral forms are called 
spirilla (singular, spirillum'). The shapes of bacteria 
have nothing to do with the diseases which they cause, 
but often give a convenient way of distinguishing be- 
tween different kinds. 
Where bacteria are found in nature. Bacteria are 
.blown about in the air, clinging to particles of dust. 
They abound in the upper layers of the soil, but in or- 
dinary soils do not live deeper than six feet below the 
surface. They are very abundant in the waters of 
streams, ponds, lakes, springs, and shallow wells, a quart 
of ordinary well water having in it something like a mil- 
lion of them. They are always found in great numbers 
about the bodies of men and animals, flourishing espe- 
cially in the mouth, nose, throat, and intestine, and on 
the skin. 
Dangerous, harmless, and useful bacteria. Some kinds 
of bacteria cause disease, and a few kinds are useful to 
man. Most of them, however, lead their little lives in 
the soil, in water, or even in our own bodies, and neither 
help nor harm us. Among useful bacteria are those 
that take a part in butter and cheese making, and those 
that help to increase the fertility of the land. The 
bacteria of decay, although they destroy much of our 
food, are also, on the whole, useful to us. Imagine what 
the world would be like if all the animals and plants that 
have lived and died in it were lying about us, and you 
will be convinced that the bacteria of decay are our 
friends and not our enemies. 
The spores of bacteria. Certain kinds of bacteria 
produce spores when hard times come upon them. A 
spore is formed by the living matter of a bacterium 20 
PRIMER OF SANITATION 
gathering itself into a little, hard ball that rests, like a 
little seed, until food, moisture, and other good condi- 
tions for growth return. Then it grows again into an 
ordinary bacterium, which goes on growing 
and multiplying as before. So very diffi- 
cult are bacterial spores to kill, that some of 
them have been found alive after they had 
been dried for ten years, and others are not 
killed by boiling them for several hours. 
Fortunately for us, the germs of none of our 
most common diseases produce spores, and 
these germs may be killed by a very moderate amount 
of heat (page 158). 
Fig. 14. The 
right-hand fig- 
ure shows a 
spore of a bac- 
terium. 
POINTS TO BE REMEMBERED 
1. Bacteria are the smallest of all living things. 
2. They multiply with astonishing rapidity by simply pinching 
in two. 
3. A bacterium is called a bacillus, a coccus, or a spirillum, 
according to its shape. 
4. Some bacteria are useful, and many of them are harmless,, 
but a few kinds produce disease. 
5. Some bacteria produce spores that are much harder to kill 
than are the bacteria themselves. CHAPTER SIX 
THE SKIN 
Without the skin to protect us, it is probable that bac- 
teria would swarm into our bodies in such numbers that 
in a week there would not be a living human being in the 
world. We know that this is true, because most of the 
bacteria that attack us enter 
the body by way of two 
small openings (the mouth 
and the nose), and because 
when even a single cut or 
tear is made in the skin, the 
body is sometimes hardly 
able to hold back the germs. 
If the inhabitants of a be- 
sieged city were hard pressed 
to defend a single open gate 
of the city, we should not 
think that they stood much 
chance of holding back the 
enemy if the whole city wall 
were thrown down. So if 
the body is hardly able to 
defend itself when there is 
only one wound in the skin, 
we should not expect it to 
keep up the fight long if the covering behind which it 
is sheltered were removed. 
The structure of the skin. The skin is composed of 
an inner layer called the dermis, and an outer layer called 
che epidermis. The hairs stand in deep narrow pockets 
that are called hair follicles. Through the epidermis, the 
epidermis 
hair 
dermis 
Fig. 15. A section of the skin. 
sweat gland 
21 22 
PRIMER OF SANITATION 
sweat glands open on the surface of the skin by little 
pores or openings. 
Bacteria that enter the body through the skin. The 
weak places in our armor of skin are the hair follicles 
and sweat glands. Through these weak points certain 
Figs. 16 and 17. If bacteria were large enough for us to see them without a 
microscope, a pencil that had been in some one’s mouth would appear some- 
thing like this, and the legs of a fly would be seen to be loaded with germs. 
bacteria do sometimes work down and cause inflamma- 
tion, pimples, boils, carbuncles, and erysipelas. These 
same bacteria also enter the body through wounds, and 
a considerable number of other disease-producing bac- 
teria get into the body either through wounds or by the 
bites of insects. 
Bacteria real living plants. In the next chapter we 
shall discuss the bacteria that enter the body through 
the skin. During your study of this chapter, as well 
as during your study of later chapters, it will help you 
greatly if you can get a clear picture in your mind of 
what bacteria are really like. Remember that the moss 
which clings to the bark of a tree is on the tree, even 
though you cannot see it from a distance. So if you 
could only see them with your unaided eyes, there are, 
as it were, great forests of bacteria growing on your THE SKIM 
23 
skin, and clusters of bacteria hanging to particles of 
dirt and to the legs of flies. Whether we see them or 
not, bacteria are real living plants, and you should be 
able to call up pictures of these little plants in your 
mind. 
You can help yourself to get clear and correct ideas 
in regard to bacteria by asking your teacher about the 
points that you do not understand, and you can learn 
much about them from a physician. For physicians 
know many things about bacteria that are not found in 
a little book of this kind; they can tell you many things 
that a teacher cannot be expected to know; and some- 
times they allow boys and girls to look at bacteria 
through their microscopes. 
POINTS TO BE REMEMBERED 
1. The work of the skin in protecting us from germs is very 
important. 
2. The skin has two layers, the dermis and the epidermis. 
3. The hairs stand in small pockets in the skin that are called 
hair follicles. 
4. The sweat glands lie in the dermis and open on the surface 
of the skin from below. 
5. Certain disease-producing bacteria enter the body through 
the hair follicles and sweat glands, through wounds, or from 
the bites of insects. CHAPTER SEVEN 
THE PUS-FORMING BACTERIA 
The pus-forming germs are among the most wide- 
spread of all the germs that are capable of causing dis- 
ease. They are found in the soil around the dwellings 
of men and of animals, they are common in unclean 
water, and they always occur’ in great numbers on the 
human skin, where they feed on the dead cells and other 
matter on the skin. There are several different kinds of 
these bacteria, but they all cause inflammation and form 
pus, the thick, creamy, liquid matter that is found in 
boils and infected wounds. 
Diseases caused by pus-forming bacteria. The pus- 
forming bacteria may grow in almost any part of the 
body and cause inflammation of the part that is attacked. 
In wounds they cause pus to be formed. In the skin 
they cause pimples, boils, car- 
buncles, and erysipelas. Very 
commonly they attack the walls 
of the throat or intestine and 
cause tonsillitis, sore throat, 
inflammation of the bowels, 
or appendicitis. Occasionally 
they attack the membranes around the brain and cause 
meningitis, or set up their growth in the lungs and cause 
pneumonia. In like manner they may grow in the 
lining of the heart, or they may spread through all the 
body and cause blood poisoning. 
The different kinds of pus-forming bacteria. The most 
common of the pus-forming bacteria is a small coccus 
(.Staphylococcus2) thjt grows in bunches or clusters 
Fig. 18. The two most common 
pus-forming germs. 
1 Pronounced staf-il-o-kok'-kus. 
24 THE PUS-FORMING BACTERIA 
25 
(Fig. 18). This coccus is the usual cause of pus in small 
wounds, of pimples, boils, and carbuncles, and of inflam- 
mation and ulcers in the bones. It may also cause 
blood poisoning, and is sometimes found in other cases 
of inflammation. 
Another common pus-forming bacterium is a coccus 
(,Streptococcusx) that grows in chains (Fig. 18). This 
germ causes erysipelas by making a widespreading 
growth in the skin. It is sometimes found in small sores 
and boils, but it more commonly attacks the inner parts 
of the body. It is often the cause of tonsillitis, appen- 
dicitis, and blood poisoning. More commonly than any 
other germ it is found in inflammation of the middle 
ear,2 and it causes meningitis and pneu- 
monia more frequently than do the other pus- 
forming bacteria. It is the most dangerous 
of all the pus-forming germs. 
A third pus-forming bacterium is a slender 
bacillus (Bacillus pyocyaneusz) that some- 
times gets into wounds and causes bluish 
green pus to be formed. It is not so common in the 
body, nor is it so dangerous, as are the other kinds of 
pus-forming germs. 
Weak and strong races of pus-forming bacteria. Some 
varieties of the pus-forming germs seem to be entirely 
harmless. Others are exceedingly dangerous, and when- 
ever they have the opportunity produce the most violent 
Fig. 19. A 
pus-forming 
bacillus. 
1 Pronounced strep-to-kok'-kus. 
2 The running ears that are common among children should receive 
prompt medical attention, both because there is danger of injury to the 
hearing, and because there is danger that germs will reach the brain and 
cause meningitis or a brain abscess. 
8 Pronounced pl-d-si-a'-ne-us. 26 
PRIMER OF SANITATION’ 
cases of inflammation and blood poisoning. None of them 
should be allowed to enter the body when it can be pre- 
vented ; but germs from a carbuncle, an old abscess, a 
case of erysipelas, or a case of blood poisoning are far 
more to be feared than germs of the same race from the 
skin or from some other source outside the body. It is 
a common thing for a person with a boil to scratch the 
germs into the skin with his fingernails, and cause a 
whole crop of boils in different parts of the body. 
Care of wounds. For our protection against pus- 
forming germs it is very important to know how to care 
for small wounds. If the 
wound has been made by a 
clean instrument and bleeds 
freely, the blood will wash 
the germs outward, and by its 
germicidal power will prob- 
ably kill any bacteria remain- 
ing in the wound. In such a 
case, the best thing to do is 
to tie up the wound “ in the 
blood,” and not open it until 
it is healed, unless inflamma- 
tion sets in. A good plan 
is to wrap the wounded part 
in a thin, clean, inner cloth, and outside of a 
second cloth. The outer cloth can be changed ffrom 
time to time when it becomes soiled, while the in'net 
cloth is left undisturbed to keep germs from getting 
into the wound. Wounds on the feet and hands, where 
dust and earth are likely to get into them, should have 
especially careful attention. 
Fig. 20. If a nail or other in- 
strument is driven through the 
skin, it will carry germs down 
and leave them among the cells. THE PUS-FORMING BACTERIA 
27 
A wound that has been made with anything unclean 
should be carefully washed in pure water, and where 
particles of earth or other 
matter have lodged in the 
wound, it is often advisable 
to use a clean cloth and pure 
soap in removing them. 
Where there is dirt in a 
wound, the wound should be 
washed with a disinfectant, 
as a five per cent solution of iodine in alcohol or ether. 
It is not best, however, to wash a wound with an irritat- 
ing disinfectant, for these disinfectants injure the cells 
in the wound and weaken their resistance to the germs. 
Turpentine is an excellent agent with which to treat a 
wound, and a new disinfectant called dichloramine-T is 
highly recommended. 
After a wound has been bandaged, it should be care- 
fully watched, and if pain, redness, or swelling shows 
that germs are growing in it, the wound should be 
opened and disinfected. A salve, such as borated 
vaseline, that contains boric acid, is often very useful 
in treating small infected wounds, and peroxid of hydro- 
gen is used to flush out larger wounds and boils and to kill 
the germs in them. Peroxid of hydrogen must be used 
with care, however, or the tissues will be injured by it. 
The pus-forming bacteria injurious to the body. It is 
a common belief that boils, pimples, and wounds that 
refuse to heal are signs of “ impure blood,” and it is 
sometimes thought that boils are beneficial to the body. 
Both these ideas are incorrect. When pus-forming 
bacteria are able to set up their growth in the body, 
Fig. 21. A solution of iodine is 
excellent for treating a wound. 28 
PRIMER OF SANITATION 
it means that the blood is weak in its power to kill 
these germs, and not that there is any impurity in the 
blood; and it no more benefits the body to have pus- 
forming bacteria kill groups of the cells and poison the 
whole system with their toxins than it would benefit it 
to be attacked by the germs of typhoid fever, pneu- 
monia, or diphtheria. 
Vaccination against pus-forming bacteria. Vaccina- 
tion with dead germs is now a common treatment for 
boils and for any long-continued infection with either of 
the more common pus-forming bacteria. A serum 
prepared from the blood of the horse is also used in 
severe infections of one of these germs (streptococcus). 
This serum is similar to diphtheria antitoxin (page 39), 
but it is prepared by repeatedly vaccinating the horse 
with dead germs and instead of an antitoxin, it contains 
a substance for increasing the activity of the white 
corpuscles. 
1. The pus-forming bacteria may grow in almost any part of 
the body. 
2. These bacteria cause inflammation, pus formation, pimples, 
boils, carbuncles, erysipelas, tonsillitis, appendicitis, blood 
poisoning, and many other diseases. 
3. There are weak and strong races of pus-forming bacteria, 
and the strong races are greatly to be feared. 
4. Wounds should be cared for, to keep germs from growing 
in them. 
5. The growth of pus-forming bacteria in the body is a sign 
that the body is weak and that the health needs attention. 
6. The resistance of the body to pus-forming bacteria may be 
raised by vaccination. 
POINTS TO BE REMEMBERED CHAPTER EIGHT 
TETANUS (LOCKJAW) 
Tetanus is not a very common disease, but it is a 
most severe one. It affects chiefly man and the horse, 
but other animals may suffer from it. The incubation 
period (the time from the entrance of the germ into 
the body to the appearance of the 
disease) is usually from four to four- 
teen days. 
The germ of tetanus. The germ of 
tetanus is a rather long bacillus. It 
forms spores that are very difficult to 
kill (page 20). The natural home of 
the tetanus bacillus is in the soil, but it 
is swallowed by grass-eating animals, such as the cow, 
sheep, and horse, and not uncommonly grows in the 
intestines of these animals (especially in the intestine 
of the horse) without causing disease. It is therefore 
very common about stables. 
So abundant are tetanus germs in certain kinds of 
soil that a handful of earth from a barnyard is almost 
certain to contain them, and the savage tribes of the 
New Hebrides Islands poison their arrows with tetanus 
germs by smearing-them with earth from crab holes in 
swamps. A peculiar thing about the tetanus bacillus is 
that, unless other bacteria are present, it cannot grow 
except when shut away from the air. Along with other 
germs, however, it sometimes grows in an open wound. 
How the tetanus germ enters the body. The tetanus 
germ enters the body through wounds, sometimes 
through wounds so small that they are not noticed. 
It is most frequently found in wounds made by unclean 
Fig. 22. Germs of 
tetanus. Most of them 
have, formed spores. 
29 30 
PRIMER OF SANITATION' 
instruments, because such wounds are most likely to get 
tetanus germs into them, and because dirt and other 
bacteria are left in wounds of this kind. It grows best 
of all in small, deep wounds, like those made by an un- 
clean nail, because such wounas readily close over and 
Fig. 23. Wounds made by these are often infected with tetanus germs, 
leave the tetanus germ, with other germs and dirt, buried 
deep in the flesh. The percussion caps used on toy 
pistols, blank cartridges, and firecrackers also make 
dangerous wounds. The tetanus spores are in dust on 
the skin, and the small, sharp, flying particles of the cap, 
the wads of the blank cartridge, or pieces of the fire- 
cracker cut deep into the flesh and drive down these 
spores along with other bacteria and dust. 
The importance of disinfecting wounds. The bacillus 
of tetanus is so common that undoubtedly it often gets 
into wounds in which it never grows. Its home, indeed, 
is in the earth, and it grows in the human body only when 
it finds conditions favorable. The disease is so danger- 
ous, however, that it is always wise to look after and 
protect every wound, especially since the same measures TETANUS 
31 
that cleanse a wound of tetanus germs will also free it 
from pus-forming bacteria. Wounds made by unclean 
instruments should therefore be carefully disinfected. 
Wounds on the feet of barefooted children also should 
receive careful attention, since these will come in contact 
with the earth and probably will get tetanus germs into 
them. It is best to have a physician look after a wound 
that is especially likely to furnish a favorable place for 
the growth of tetanus germs; for usually the disease 
develops suddenly and without any symptoms, often 
days after the wound is supposed to be healed.1 
The toxin of tetanus. The tetanus germ makes only 
a very little growth in the body, but it produces a toxin 
of tremendous power. This toxin for man is a poison 
twenty times as strong as dried cobra venom, and almost 
three hundred times as strong as strychnin. It poisons 
the nervous system and causes all the muscles to be 
thrown into contraction. One of the first symptoms of 
tetanus is a stiffness of the muscles of the jaw and neck. 
Tetanus antitoxin. An antitoxin for tetanus is pre- 
pared from the blood of the horse, but it has not proved 
very valuable in curing the disease, except when used 
in the early stages and in large doses. It is very valu- 
able, however, in preventing the disease, and when a 
person has received a wound that is likely to bring on 
tetanus, a dose of the antitoxin should be given. When 
this is done, the disease is almost certain to be prevented.2 
1 Closing wounds with court plaster shuts out the air and creates con- 
ditions favorable for the growth of the tetanus germ. 
2 In 1903 there were in the United States 406 deaths from tetanus 
following 4449 Fourth-of-July injuries, while in 1907, when antitoxin was 
more extensively used, there were only 62 deaths from 4413 injuries. 32 
PRIMER OF SANITATION’ 
Other germs that infect wounds. In addition to the 
pus-forming bacteria and the tetanus bacillus, there are 
a number of other germs that often infect wounds in 
which the tissues are badly crushed and into which dirt 
or other foreign matter has been carried. One of these, 
a relative of the tetanus germ and commonly called the 
gas bacillus, produces a terrible inflammation. Like the 
tetanus germ, the gas bacillus produces a toxin, for which 
an antitoxin has been discovered. During the recent war 
great advances were made in the treatment of wounds of 
all kinds, and a physician who understands the new 
methods of preventing infection should be called to 
attend to any severe wound. 
POINTS TO BE REMEMBERED 
1. The tetanus bacillus has its home in the soil and is commonly 
found about stables. 
2. It enters the body through wounds. 
3. Usually it grows only in deep wounds and in wounds that 
dirt gets into. 
4. Wounds of a kind that are especially likely to bring on teta- 
nus should be looked after by a physician. 
5. The toxin of the tetanus germ is extremely powerful. 
6. Tetanus antitoxin is more useful in preventing tetanus than 
in curing it. 
7. It is advisable to give a dose of tetanus antitoxin as a pre- 
ventive measure when a wound that may cause the disease 
to develop has been received. 
8. Several dangerous bacteria besides the tetanus bacillus live 
in the soil. 
9. The presence of these germs in earth makes it the more 
necessary to care for wounds. CHAPTER NINE 
THE AIR PASSAGES AND THE LUNGS 
The air passages consist of the nasal chambers (nose) 
the pharynx (throat), the larynx (voice box), and the 
trachea (windpipe) and its branches (bronchial tubes'). 
The lungs are composed chiefly of air passages (bronchial 
tubes), some of which 
are very fine, and of 
millions of little air sacs 
that lie at their ends. 
The tonsils are two 
rounded elevations in 
the side walls of the 
pharynx. A tube from 
each of the middle ears 
opens into the pharynx. 
Communicable dis- 
eases of the air passages 
and lungs. Among the 
common germ diseases 
of the air passages are 
colds, catarrh, influenza, 
tonsillitis, bronchitis, diphtheria, and whooping cough. 
The most dangerous diseases of the lungs are consump- 
tion and pneumonia, which in the United States stand 
at the head of the list of germ diseases as causes of 
death. The air passages are infected in measles, scar- 
let fever, and smallpox also; and in mumps, meningitis, 
and infantile paralysis the germs are in the discharges 
from the mouth and nose. As will be seen, this is a 
formidable list of infections, and their control is now the 
most pressing problem in public health. 
Fig. 24. The solid arrows show the path 
of the air to the lungs; the dotted arrow, 
show the path of the food to the stomach. 
33 34 
PRIMER OF SANITATION 
How the germs of respiratory diseases are spread. The 
germs of respiratory diseases enter the body and leave 
the body through the mouth 
and nose. They reach the 
hands more easily than the 
germs of other diseases and 
pass more readily from one 
person to another, and in the 
army cantonments during the 
great war they were the dis- 
eases that were most difficult 
to control. From our present 
knowledge it seems probable 
that the germs are conveyed 
from one person to another 
chiefly by the hands; by public drinking cups and the 
dishes and glasses in public eating places and soda 
fountains; and by being coughed and sneezed out into 
the air (page 37). How important each of these methods 
of infection is we do not yet know. In certain army 
cantonments and among the workers in a number of 
public eating places there was less than one fifth as much 
influenza where the dishes were washed in boiling water 
as where they were washed by hand. One health officer 
conducted a state-wide campaign based on the two simple 
ideas of smothering coughs and sneezes and of keeping 
the hands away from the face, and he believes that by 
this campaign he reduced the respiratory infections in 
his state by 30 per cent. 
Preventing respiratory diseases. Patients suffering 
from respiratory diseases must be isolated to prevent 
the spread of the germs, and coughs and sneezes should 
-larynx 
-trachea 
hronchiaC 
\ tube 
-lung 
air 
sacs 
Fig. 25. The lungs. THE AIR PASSAGES AND THE LUNGS 
35 
be covered. To avoid these diseases a person should not 
touch objects that have been touched by others; he should 
not shake hands unless it is 
necessary; he should avoid 
public drinking cups and 
public eating and drinking 
places where the dishes are 
not sterilized; he should 
keep his hands away from 
his face and should wash 
them thoroughly with soap 
before eating; he should 
avoid crowds if possible; and he should keep himself in 
the best possible health so that his resistance to the 
germs will not be lowered. Experiments prove that 
fresh air increases the resistance of animals to germs, 
and all experience indicates that outdoor life, outdoor 
sleeping, and good ventilation are important in building 
up the defenses of the body. 
Fig. 26. Air sacs that lie at the ends 
of the small bronchial tubes in the 
lungs. 
POINTS TO BE REMEMBERED 
1. The air passages and lungs are favorable places for the 
growth of germs. 
2. The germs of respiratory diseases are spread chiefly by 
the hands, by public glasses and dishes, and by coughing 
and sneezing. 
3. Patients suffering from respiratory diseases should be 
isolated, coughs and sneezes covered, and the hands kept 
away from the face. 
4. A strong, healthy condition of the body is a great protec- 
tion against some respiratory diseases. 
5. Fresh air strengthens the body against the germs of these 
diseases. CHAPTER TEN 
DIPHTHERIA 
Some cases of diphtheria are so severe that death 
comes in a day or two. Other cases are so light that 
they are mistaken for colds in the head or for simple 
sore throats. The disease is most common in children, 
and there is always an increase in the number of cases 
when the children come together in school after the 
long vacation. The incubation period is usually from 
two to eight days, but may be less. 
The germ of diphtheria. The diphtheria germ is a 
bacillus. It grows most frequently in the throat, but 
often it is found in the mouth, nose, 
and larynx.1 It may grow also on the 
lips, on the lining of the eyelids, and 
in other parts of the body. 
The diphtheria bacillus does not 
usually grow outside the human body, 
except when it gets into milk. In most 
cases it is killed by drying, but when 
it is protected by matter about it, the bacillus can live for 
some time. On slate pencils that had touched the lips 
of children who were in the early stages of diphtheria, 
the germs were found to be alive after several days, and 
in dried “ membranes ” from the throats of diphtheria 
patients it is known that the germs can live for months. 
How diphtheria germs get into the body. Diphtheria 
germs enter the body by way of either the mouth or 
the nose. They are passed from one person to another 
Fig. 27. The bacillus 
of diphtheria. 
1 Diphtheria of the larynx is the disease often called membranous 
croup. 
36 DIPHTHERIA 
37 
in various ways. They may be coughed out into the air 
and inhaled,1 or by spitting they may be spread about 
in a most dangerous manner. 
They are almost certain to be on 
the handkerchiefs of the persons 
who are carrying these germs, 
and they can easily get on door- 
knobs, books, or furniture. They 
have been found on public drinking 
cups, and they may be on pencils, 
chewing gum, pieces of candy, 
toys, or any of the other objects 
that are handled and passed around 
by children. A number of diph- 
theria epidemics have been caused 
by milk (page 154), and flies may 
carry the germs about and leave 
them where they will reach the 
mouth and throat. Cats suffer 
from diphtheria and spread the 
disease, and other domestic animals probably do the 
same. 
Difficulties in controlling diphtheria. In spite of 
quarantining and the use of antitoxin, there were over 
Fig. 28. Diphtheria germs 
have been found on pencils. 
1 In coughing, sneezing, laughing, and to a certain extent in talking, 
small droplets of liquid are sent out into the air. They may fly to a dis- 
tance of several feet (three to and some of them are so very fine 
that they are said to float in the air for as long as twenty minutes. When 
a person is suffering from a disease like diphtheria, pneumonia, or con- 
sumption, these droplets are, of course, filled with the germs of the disease. 
One should not stand near a person who is coughing, and a sick person 
should hold a handkerchief or a paper napkin before his face, when he 
coughs. 38 
PRIMER OF SANITATION 
17,000 deaths from diphtheria in the United States 
during 1916. The chief difficulty in stamping it out is 
that the germs often linger in the throat for four or five 
weeks, and occasionally for several months, after re- 
covery from an attack of diphtheria. The germ is found 
also in the throats of a considerable number of healthy 
persons1 (often in those who have been in contact 
with cases of the disease), and in the noses and throats 
of persons who seem to be suffering only from ordinary 
colds or from light cases of sore throat. As a fire 
sometimes bursts forth into flames again after it seems 
to be dead, so diphtheria, after it seems to have disap- 
peared, often breaks forth anew from these germ 
carriers. For at any time one of these persons may 
pass on to others germs that will cause the most 
severe cases of the disease; or if his resistance to 
the germs runs low, he himself may be overcome 
by them. 
Quarantining in cases of diphtheria. To control 
diphtheria, every one who is carrying virulent diph- 
theria germs must be shut up in quarantine, whether 
he be sick or well. It should be understood that 
in doubtful cases it is not possible for a physician 
to tell by looking at the throat whether or not 
1 Investigations indicate that when diphtheria is in a city or town, from 
three to five healthy persons in every thousand carry virulent diphtheria 
germs in their throats. In these persons the body is holding the 
germs in check so that they cannot multiply enough to produce the 
disease, but it is not able to destroy them entirely. 
Many persons (the majority of adults) are immune to diphtheria. It is 
possible to determine by a simple skin test who these persons are and it is 
not necessary to give them antitoxin when they have been exposed to the 
disease. Persons not immune can be made so by the use of a mixture of DIPHTHERIA 
39 
it is free from diphtheria bacilli. To determine 
this, a microscopical examination for the germs must 
be made. 
Diphtheria toxin. The diphtheria germ occasionally 
produces death by causing the 
throat to close, but the usual 
cause of death in diphtheria is 
the very powerful toxin. So 
poisonous is this toxin that a 
patch of diphtheria germs the 
size of the thumbnail growing 
on the tonsil may produce toxin 
enough to cause death. The toxin 
attacks especially the nervous 
system, the kidneys, and the 
heart. 
The antitoxin treatment for 
diphtheria. In a former chapter 
(page 12) we learned that when 
disease germs produce toxin in 
the body, the body works up an 
antitoxin to destroy the toxin and 
save itself from being poisoned. 
Working in accordance with this principle, scientists 
have learned how to get a diphtheria antitoxin from the 
1st 
day 
2nd 
day 
no deaths 
3 deaths 
3rd 
day 
4th 
day 
11 deaths 
19 deaths 
5th 
day 
Fig. 29. Showing the num- 
ber of deaths in 100 cases 
of diphtheria when anti- 
toxin is used on the first, 
second, third, fourth, and 
fifth days. The sooner an- 
titoxin can be used in this 
disease, the better. The fig- 
ures are taken from the 
experience of the London 
hospitals. 
20 deaths 
toxin and antitoxin, and the inmates in a number of children’s homes have 
been protected in this way. It is probable that this method will be em- 
ployed to protect nurses and others who are especially exposed to the germs. 
Like vaccination against smallpox and typhoid fever, it may be generally 
used to check the spread of the disease. 
Chronic carriers of diphtheria germs usually have diseased tonsils, and 
removal of the tonsils causes such persons to become free from the germs. 
Infected tonsils seem also to make one more liable to the disease. 40 
PRIMER OF SANITATION 
blood of the horse.1 When a person is attacked by 
diphtheria, some of the antitoxin from the horse is in- 
jected into the body. This does not kill the diphtheria 
germs, but destroys their toxin and 
saves the cells from poisoning until 
the body can kill out the germs and 
so stop the disease. 
It is very important that the anti- 
toxin be given in the early stages of 
diphtheria, for after the toxin has 
poisoned the cells of the nervous sys- 
tem, kidneys, and heart, great damage 
has been done, and it is not possible 
to undo it. Antitoxin is useful in all 
stages of the disease, however, and 
should always be used. It is also very 
useful in preventing diphtheria, and 
when a person has been exposed to 
the germs, a dose of antitoxin is often 
given to prevent the development of 
the disease. 
The results of the antitoxin treatment. From the 
beginning of its use in the treatment of diphtheria, 
no antitoxin 
anti- 
toxin 
Fig. 30. When no 
antitoxin is used in the 
treatment of diphthe- 
ria, about forty-four 
patients in a hundred 
die. When antitoxin is 
used, there are only one 
fourth as many deaths 
(eleven in a hundred). 
1 The antitoxin is prepared in the following manner: Diphtheria germs 
are placed in beef broth, where they multiply and produce great amounts 
of toxin. A little of this toxin is then injected into the blood of a horse, 
and the horse begins to work up antitoxin to destroy it. A larger dose 
of toxin is then given to the horse, and still more antitoxin appears in the 
blood. More and more of the toxin is injected, until the blood of the 
horse is made as strong in antitoxin as possible. Then the horse is bled 
and the blood allowed to clot. The thin yellow liquid (serum) that 
appears around the clot contains the antitoxin. After being freed from 
certain impurities, this serum is sealed up in glass containers and sold as 
antitoxin. DIPHTHERIA 
41 
antitoxin has been a great success. Indeed, when anti- 
toxin is given in the very early stages of the disease, 
there are almost no deaths; and in some states when a 
death from diphtheria is reported an investigation is made 
to determine who was responsible for the failure to use 
the antitoxin in time. It should be understood that the 
paralysis which sometimes follows diphtheria is not 
caused by antitoxin, but by the disease. After an attack 
of diphtheria the heart is weak, and violent exercise 
should not be taken. 
POINTS TO BE REMEMBERED 
1. The diphtheria germ usually grows only in the body, but it 
may live for some time outside the body. 
2. It is transferred from one person to another in many dif- 
ferent ways. 
3. It is often found in the throat long after the patient has re- 
covered, and is occasionally found in the throats of healthy 
persons. 
4. Every one who is carrying virulent diphtheria germs should 
be quarantined, whether he is sick or well. 
5. The diphtheria germ produces a very powerful toxin that 
poisons especially the cells of the nervous system, the kid- 
neys, and the heart. 
6. By injecting diphtheria toxin into a horse, the blood of the 
horse can be made very strong in antitoxin. 
7. If this antitoxin is used when a person is attacked by diph- 
theria, it saves the body from being poisoned. CHAPTER ELEVEN 
PNEUMONIA 
Up to about ten years ago consumption caused more 
deaths in all parts of our country than any other germ 
disease. Now a better understanding of how to avoid 
the germ of consumption, and a better knowledge of how 
to treat the disease, have considerably lessened the death 
rate from consumption; and in some of our northern 
states the pneumonia germ now claims more victims 
than any other of our microbe enemies. Each year it 
causes about 125,000 deaths in the United States. 
Pneumonia is much more common in cities than it is in 
the country, probably because in a city, where the people 
are crowded together, the germ is more easily passed 
from one person to another, and because fresh air is less 
abundant in the city than it is in the country. 
The character of the disease. Pneumonia usually 
begins with a chill (often a very severe one), cough, 
fever, pain in the side, and rapid breathing. The 
sputum has a rusty color caused by blood from the air 
sacs of the lungs. The disease runs a swift and severe 
course, the crisis coming usually in from three to eight 
days. In rare cases death is caused by the closing of 
the air sacs in so great a portion of the lungs that the 
patient cannot breathe, but more commonly the heart is 
overwhelmed by the toxin that is carried from the dis- 
eased lungs by the blood. Pneumonia attacks particu- 
larly children under five years of age, aged persons, and 
those who for any reason are weak or sick. Users 
of alcohol are especially liable to pneumonia, and all 
physicians know that drinkers fare badly when attacked 
by this disease. 
42 PNEUMONIA 
43 
The germ of pneumonia. Pneumonia may be caused 
by a number of different germs, but in most cases a 
small coccus1 is the invader. This germ 
grows not only in the lungs but also in the 
nose, mouth, throat, and air passages; in 
children it is a very common cause of inflam- 
mation in the middle ear, and it is sometimes 
the cause of meningitis. The pneumonia 
germ attacks many animals, and it is possible 
for man to get the disease from animals. 
pneumonia 
menin 
gitis 
all other 
diseases 
accidents, 
etc. 
tuber- 
culosis 
measles 
scar- 
let 
fever 
diph- 
the- 
ria 
typhoid 
fever 
Fig. 31. Diagram showing death rate in U. S. Army for six months (Sept. 29, 
1917, to March 29, 1918) from pneumonia as compared with other diseases. 
How pneumonia germs enter the body. Pneumonia, 
like diphtheria, is an infectious disease. The germs are 
in the sputum and often in the discharges from the nose 
of a pneumonia patient; they are passed from one per- 
son to another in all the ways that diphtheria germs are 
spread abroad (page 37); and they enter the body 
through the mouth or nose. The germs are killed by 
drying, and outside of the body they quickly die. 
Preventing the spread of the germs. Pneumonia, like 
diphtheria, is a communicable disease. No one should 
go about a pneumonia patient except those who are 
1 Pneumococcus (neu-mo-kok'-kus). In the army cantonments during 
the great war, the streptococcus was also a common cause of pneumonia. 44 
PRIMER OF SANITATION- 
waiting on him, and the sputum of the patient should 
be destroyed.1 The avoidance of crowding is also im- 
portant in preventing pneumonia. Among the laborers 
on the Panama Canal it was the most troublesome dis- 
ease ; and in the army cantonments, during the recent 
war, it led all infections as a cause of death. It is be- 
lieved that a method of vac- 
cinating that gives protection 
against the disease has been 
found. 
Preventing pneumonia by 
keeping up the health. The 
pneumonia germ is one of the 
most widespread of disease 
germs, and it is not always 
possible, try as we may, to 
avoid it. During pneumonia 
epidemics, therefore, it is ad- 
visable to make a special ef- 
fort to keep up the general 
health so that the body may 
be able to kill any pneumonia 
germs that may reach the 
lungs. To keep up the health 
a person should avoid all ex- 
posure to wet and should wear sufficient clothing to 
protect himself from cold. He should avoid alcoholic 
drinks, for the man whose power to resist germs is 
FlG. 32. Kiss the baby on the 
cheek, not on the mouth. If it 
isn’t your own baby, do not kiss 
it at all. 
1 A physician reports the following as occurring in a rural community: 
An elderly woman suffered a severe attack of pneumonia. Two women 
from neighboring families who helped care for her contracted the disease. 
The husbands of these women were next stricken, and two other persons 
also were attacked. Two of the seven cases ended in death. PNEUMONIA 
45 
lessened by drink falls into the hands of a terrible foe 
when the pneumonia germ attacks him. A person should 
also eat good food, take plenty of sleep and exercise, 
and should spend as much time as possible in the open 
Fig. 33. Pneumonia patients being treated in the open air. (After photograph 
of patients in the Presbyterian Hospital, New York.) 
air. Anything that builds up the general health is a safe- 
guard against pneumonia, and anything that weakens the 
body may bring on pneumonia. In some of the army 
camps it was noticed that respiratory diseases increased 
when the ground thawed and the men’s feet became wet. 
The importance of fresh air. There is little doubt 
that the resistance of the body to pneumonia germs i# 
often weakened by a lack of fresh air. By many it is 
believed that the large .number of pneumonia cases in 
February and March is to be accounted for on the 
theory that we have been weakened by living indoors 
all winter, often in houses that are not sufficiently ven- 
tilated. Physicians and boards of health are more and 
more recommending fresh air as a means of keeping up 46 
PRIMER OF SANITATION 
the health, and in treating pneumonia some of the most 
successful physicians carry the patients outdoors even 
in the coldest weather, as is done in the treatment of 
consumption. Any one who wishes to keep up his re- 
sistance to the pneumonia germ cannot afford to neglect 
the fresh air factor. 
POINTS TO BE REMEMBERED 
1. Pneumonia causes more deaths in our country than any 
other germ disease except consumption. 
2. It runs a swift course, and death is usually due to toxins 
that are carried out of the lungs in the blood. 
3. Pneumonia may be caused by several different germs, but 
it is nearly always due to a small coccus (the pneumo- 
coccus) . 
4. This germ may grow in other parts of the body besides the 
lungs, and attacks animals as well as men. 
5. The pneumonia germ spreads by contact infection and 
enters the body through the mouth and nose. 
6. The sputum of pneumonia patients should be destroyed, 
and pneumonia should be treated as an infectious disease. 
7. The avoidance of crowding is important in the prevention 
of pneumonia. 
8. It is believed that a successful method of vaccinating 
against pneumonia has been found. 
9. The pneumonia germ is widespread, and we should keep 
up the health and the germicidal power of the body to 
protect us from this disease. 
10. Fresh air is one of the greatest factors in building up the 
resistance of the body to pneumonia. CHAPTER TWELVE 
INFLUENZA, WHOOPING COUGH, AND COLDS 
INFLUENZA 
Influenza (grip) was little known in the United 
States until 1889-1890. Then a great epidemic swept 
over the country, and the 
disease has been common 
with us ever since. It is, 
however, an ancient dis- 
ease, and epidemics of it 
were common in Europe 
in the Middle Ages. It 
was also common in other 
parts of the world before 
its introduction into the 
United States. Usually it 
causes in the United States 
about 12,000 to 15,000 
deaths a year, but in 1918 
a great epidemic broke 
out, and in six months 
more than a half million 
of our people died of it. 
The germ of influenza. 
Influenza is probably caused by a filterable virus (page 194). 
The germs are in the sputum and the discharges from the 
nose, and it is probable that the disease is communicable 
only in the early stages. The incubation period is very 
short, and it is the most catching disease known. 
Influenza a serious disease. The influenza germ pro- 
duces a powerful toxin that has a profound effect upon 
Fig. 34. A letter carrier during the 
great influenza epidemic. 
47 48 
PRIMER OF SANITATION' 
the whole body. It does not poison the body so acutely 
as does the toxin of the diphtheria germ, but it causes 
a depression and weakness that often last for months. 
Another bad feature of the disease is that other troubles, 
such as pneumonia, consumption, eye and ear diseases, 
bronchitis, and colds, often follow it, and it may leave 
a part of the body, as the stomach, the kidneys, or the 
nervous system, in a weakened condition. Because it is 
so widespread, and because its after-effects are so serious, 
influenza is a much-dreaded disease. The most impor- 
tant point in the treatment of the disease is for the 
patient to go to bed at once and remain in bed until the 
danger is over. 
Guarding against influenza. Influenza is so infectious 
that only a most careful quarantine of first cases will con- 
trol it. Masks have proved 
helpful in some hospitals in 
protecting nurses and physi- 
cians from respiratory dis- 
eases, but most health officials 
seem to think that the public 
will not wear them in a way 
to make them of much use in 
influenza time. To be effec- 
tive, masks must be made of 
closely woven material, they must be changed frequently, 
and they must not be turned wrong side out after being 
worn. To protect a person from germs coughed out by 
others a mask should cover the eyes as well as the mouth 
and nose. Good health is no protection against the 
disease. In the great 1918 epidemic the well and those 
in the prime of life were especially attacked. 
Fig. 35. In droplets that are 
coughed out into the air the germs 
of influenza, colds, and other res- 
piratory diseases are found (see 
footnote, page 37). INFLUENZA, WHOOPING COUGH, AND COLDS 
49 
WHOOPING COUGH 
The incubation period of whooping cough is usually 
from four to fourteen days, but it may be as long as 
three weeks, and the “ whoop ” may not show itself for 
some time after the commencement of the attack. It is 
especially infectious in the very early stages. A child 
may be permitted to return to school in five weeks after 
the beginning of the whoop, provided the severe cough- 
ing spells have ceased. 
Whooping cough dangerous to children. Whooping 
cough is not usually supposed to be very dangerous, 
and often cases of it are not carefully quarantined. As 
a consequence, it is a widespread disease and causes 
more deaths than scarlet fever and smallpox combined — 
more than any of the other common infectious diseases 
of children. Some persons make no effort to protect 
their children from whooping cough, or even purposely 
expose them to it. This is the most pernicious practice, 
for more than four fifths of all deaths from whooping 
cough are among children under two years of age. The 
older a child is, the better he resists the disease, and 
an adult usually either escapes it altogether or has a 
mild attack. 
Quarantining in cases of whooping cough. To children 
under five years of age, whooping cough is a very dan- 
gerous disease, and cases of it ought not to be allowed 
to run unchecked with the idea that every one must have 
it. During quarantine the patient need not be shut up 
indoors, but he ought to keep away from others who 
might become infected with the germs. A vaccine is 
now prepared that will often prevent the disease. It PRIMER OF SANITATION 
50 
will also shorten and lessen the severity of the attack if 
used promptly when the first symptoms appear. Dogs 
and cats suffer from whooping cough, and during epi- 
demics they may be a means of spreading the germs. 
COLDS 
Colds are caused by germs that are transferred from 
one person to another. In no other way can the fact 
that they run in epidemics be explained.1 They are 
the most common of all 
the germ diseases of tem- 
perate climates, and the 
most difficult to avoid. 
The germs pass easily 
from one person to an- 
other, and it is astonish- 
ing how quickly an epi- 
demic can spread through 
a community. 
The cause of colds. The first cause of an epidemic 
cold is probable a filterable virus (page 194). In later 
stages of an acute cold and in chronic colds, bacteria, 
often several different kinds together, are found grow- 
ing in great numbers in the air passages. Among the 
bacteria commonly present are the pneumonia germ, 
pus-forming bacteria (especially streptococcus), a bacil- 
lus that sometimes causes pneumonia,2 a small coccus 
Fig. 36- The germs of colds pass 
easily Irom one person to another. 
11 have long been satisfied from observation that people often catch 
cold from one another when shut up in close rooms and coaches, and when 
sitting near and conversing so as to breathe in each other’s transpiration. 
— Benjamin Franklin. 
2 Pneumo-bacillus. INFLUENZA, WHOOPING COUGH, AND COLDS 
51 
often found in catarrh, and a small bacillus often present 
in influenza. In ordinary colds it is probable that the 
filterable virus first attacks 
and weakens the linings of 
air passages and that the 
bacteria then set up their 
growth on them. 
Catarrh and bronchitis. 
Catarrh is a chronic cold, 
and bronchitis is a cold of 
the lining of the trachea 
and bronchial tubes. The 
small coccus (Micrococcus 
catarrhalis) that is some- 
times present in ordinary 
colds is very frequently 
found in chronic catarrh, 
and the pneumonia germ 
and pus-forming bacteria 
(streptococci) are common in cases of bronchitis. 
Chronic catarrh and bronchitis are difficult diseased to 
cure, and they should not be allowed to fasten them- 
selves on children. 
Avoiding the germs that cause colds. A person who 
is trying to avoid the germs of colds should not borrow 
pencils, books, or other articles from any one who has 
a cold; he should not touch soiled handkerchiefs, use 
public drinking cups, or stand near any one who is 
coughing without turning away from him; he should 
keep his hands away from his own mouth and nose, 
and should frequently wash his hands thoroughly with 
soap and water (page 161). He should also avoid wet 
Fig. 37. Benjamin Franklin, who was 
one of the shrewdest men and one of the 
best scientists of his day. More than 
a hundred years ago he observed that 
people catch colds from each other. PRIMER OF SANITATION 
52 
feet, chilling the body, alcoholic drinks, or anything else 
that will lower his resistance to germs. A person who 
has a cold should change handkerchiefs frequently, turn 
Fig. 38. One way in which the germs of colds and other respiratory diseases 
may be passed from one person to another. 
away from others when he coughs, disinfect his hands 
occasionally, and in other ways try to prevent the 
spread of the germs. 
POINTS TO BE REMEMBERED 
1. Influenza is a serious disease, and the germs should be 
avoided as much as possible. 
2. A person with influenza should go to bed at once. 
3. Whooping cough is a serious disease and should be quar- 
antined. 
4. Colds, catarrh, and bronchitis are caused by germs growing 
in the air passages and throat. 
5. These diseases are infectious, and care should be taken to 
prevent the spread of the germs. 
6. Keeping up the resistance of the body is an important safe- 
guard against colds. CHAPTER THIRTEEN 
TUBERCULOSIS 
Probably from the earliest times, mankind has been 
afflicted with tuberculosis, for a great Greek physician 
named Hippocrates wrote a treatise on consumption in 
400 b.c., and in the lungs of Egyptian mummies the 
marks of consumption have been found. At the present 
time Bacillus tuberculosis, or the tubercle bacillus, as it is 
sometimes called, is the most deadly of all the bacterial 
enemies of man. In our own country, more than one tenth 
of all deaths are caused by this germ, which means that 
the “ Captain of the Men of Death ” is killing our fellow- 
countrymen at the rate of 150,000 a year, over 400 a day, 
and one every three and a half minutes. Years ago 
Oliver Wendell Holmes called consumption the Great 
White Plague, and it richly deserves the name. 
The cost of tuberculosis. Because tuberculosis selects 
its victims especially from those who are in the active 
working years of their lives,1 and because it is a lingering 
illness, it costs us far more in money than does any 
other disease. It is difficult to calculate the cost of 
sickness in dollars and cents, but one estimate that has 
been widely accepted places the cost of tuberculosis to 
our country at a billion dollars a year. Just now great 
a sum this is you will realize better when you know that 
it is more than two sevenths as much as the yearly wages 
of all the factory workers in the United States, nearly 
one half more than the whole country spends on its pub- 
lic and high school system, and nearly ten times as much 
as it spends on its colleges and universities. Yet the 
1 One third of all deaths between the ages of fifteen and forty-five are 
from tuberculosis. 
53 54 
PRIMER OF SANITATION 
death rate from tuberculosis has fallen amazingly in 
the last thirty years, and it would be a simple matter to 
prevent nearly all cases of the disease. 
The germ of tuberculosis. The germ of tuberculosis is 
a slender bacillus. It is a slow-growing bacterium, but it 
is a very hardy one, and often it resists all 
attempts of the body to kill it and grows 
steadily on until it causes death. Outside the 
bodies of men and animals it does not grow at 
all in nature, and light and drying kill it. Yet 
in a dark, damp house the germs in the sputum 
of a consumptive may live for several months 
or perhaps for a whole year. Away from the habita- 
tions of men and animals the tubercle bacillus is not 
found, but it is often present in the earth and refuse 
about places where cattle are kept, and in the rooms of 
careless consumptives. 
Different forms of tuberculosis. The tubercle bacillus 
may grow in almost any part of the body and cause 
tuberculosis of the part attacked. Tuberculosis of the 
lungs, or consumption, is the best-known form of the dis- 
ease, and causes by far the most deaths. Tuberculosis of 
the bones is also a common trouble, and most of the lame 
and crippled people that we see have been deformed by 
tuberculosis of the spinal column, or of the bones of the 
hips, legs, or feet. Tuberculosis of the bones is especially 
common among children, as is also scrofula, or tubercu- 
losis of the lymphatic glands. Tuberculous meningitis, 
which causes more deaths than any other form of tuber- 
culosis except consumption, is more common among 
children than among older persons. The skin, kidneys, 
intestine, larynx, and other parts of the body also may 
Fig. 39. The 
bacillus of 
tuberculosis. TUBERCULOSIS 
55 
be attacked by this germ ; and when the tubercle bacillus 
is growing anywhere in the body, it is always possible 
for it to be carried by the blood to the lungs. 
How the tuberculosis germs enter the body. It is not 
possible in most cases of tuberculosis to tell how the 
germ got into the body. There is no doubt, however, 
Fig. 40. Many of the lame and crippled people that we see have been 
deformed by tuberculosis of the bones. 
that some cases come from breathing in germs from 
dried sputum and from droplets that have been coughed 
out by consumptives, and that many other cases come 
from germs that have been swallowed and that have 
passed through the walls of the intestine into the blood. 
It is probable that the germ gets into the body by way of 
the mouth more commonly than was formerly supposed. 
How tuberculosis germs are scattered. The form of 
tuberculosis that is most dangerous to those about the 
patient is consumption. In this disease, the germs may 
be coughed out into the air in droplets of saliva, they 
may be carried by flies if all sputum is not carefully de- 56 
PRIMER OF SANITATION 
stroyed at once, and they may be spread abroad in all the 
ways that pneumonia and diphtheria germs are scattered 
(page 37). Dishes that have been used by a consumptive 
are a source of danger unless they are disinfected, and 
food that a consumptive has prepared or touched may 
contain the germs. The tuberculosis germs may also be 
in milk or water, they may be carried on the feet from 
sidewalks and other places where people spit, and in 
almost countless other ways these germs can reach the 
mouth and nose. They can withstand considerable 
drying, and in dried sputum they remain alive and viru- 
lent after the germs of most other common diseases 
would be dead. This makes especially dangerous the 
habit of spitting that some careless consumptives have, 
for in the advanced stages of the disease several billion 
germs are thrown off daily from the 
lungs. Indeed, it is not right for any 
one to spit in public places, for it is 
probable that more than one half of the 
people in our country who have con- 
sumption, do not know that they are 
afflicted with the disease. 
Disinfecting sputum. The impor- 
tance of destroying the sputum of con- 
sumptives cannot be too strongly in- 
sisted on. It should be received either 
in pasteboard cups that can be burned, or in a vessel 
that contains a disinfectant. Carbolic acid is a good 
disinfectant to use for this purpose, but lysol is better, 
for it dissolves the mucus of the sputum and allows the 
disinfectant to get quickly to the germs (page 160). 
When the consumptive is traveling, the sputum may be 
Fig. 41. A water- 
proof pasteboard spu- 
tum cup. These are 
very cheap and they 
should be burned after 
being used. TUBERCULOSIS 
57 
received in waterproof envelopes or pocket sputum cups 
that are made for the purpose, or on pieces of cloth that 
may be carried in a paper bag until a fire is reached 
The sputum should not be swallowed, 
for if this is done, the germs may set 
up intestinal tuberculosis, or they may 
pass through the intestinal wall, be 
carried away in the blood, and start the 
disease in some part of the body that 
has not yet become infected. Under 
no circumstances should the sputum be 
allowed to dry, for in the dry condition 
it is impossible to keep the germs from 
being scattered about. 
Other precautions to be taken. A con- 
sumptive should hold a paper napkin 
or a handkerchief before his face when he coughs, and 
these napkins or handkerchiefs should be burned, or 
placed in a disinfectant, or kept in water until they can 
be boiled. A consumptive should learn to keep his 
hands away from his face and mouth, and should occa- 
sionally wash his hands in a disinfectant. He should 
have his own dishes, and these should never be washed 
with other dishes, nor allowed to come in contact with 
them until after being boiled for at least five minutes. 
His bedclothes, clothing, and furniture ought occasionally 
to be disinfected, or at least exposed to the bright sun- 
shine as much as possible, and his clothing should be 
boiled before it is washed with other clothes. A con- 
sumptive should have a sleeping room to himself, and 
this room should be kept bright and well ventilated, to 
help kill any germs that may be free in it. A house in 
Fig. 42. A pocket 
sputum cup, to be 
burned after being 
used. 58 
PRIMER OF SANITATION' 
which a consumptive has lived should be disinfected be- 
fore any one else moves into it.' 
Danger from a consumptive. In Indiana in 1910 the 
state health officials inves- 
tigated more than 900 new 
cases of consumption and 
found that in more than 
half of them the patient 
had been living or work- 
ing with a consumptive. 
These and other recent 
studies indicate that those 
who live with consump- 
tives run a great risk of 
becoming infected with 
the germs (page 200). 
A consumptive should, 
therefore, take great care 
not to endanger those about him. Any one who lives 
with a consumptive should take the greatest care to 
guard against infection, and he should be especially 
careful of his health so that his body will at all times 
have as much resistance as possible to the germs. 
Alcoholism and tuberculosis. In a former chapter 
(page 15) it was stated that alcohol lessens the power of 
the body to kill germs and that the death rate from con- 
sumption is much higher among brewers than among 
ministers; also that the person who uses alcohol makes 
himself more liable to tuberculosis. So closely connected 
are the use of alcoholic drinks and tuberculosis that in 
Paris, in 1905, the International Tuberculosis Congress 
adopted the following resolution : “ We strongly emphasize 
Fig. 43. This house stands at the edge 
of a small village. Sunshine and pure 
country air are abundant about it, but 
the house is infected with tuberculosis 
germs. In six years three different 
families lived in it, and each of these 
families had one or more members 
stricken with consumption while living 
in the house. TUBERCULOSIS 
59 
the necessity and importance of combining the fight against 
tuberculosis with the struggle against alcoholism.” 
TUBERCULOSIS IN ANIMALS 
Tuberculosis is a common disease of chickens and 
turkeys, but the tubercle bacillus of birds does not seem 
to be able to attack man. Many domestic animals also 
suffer from tuberculosis, the disease - being especially 
common among cattle and among hogs that have run in 
barn lots with tuberculous cattle or have been fed on 
milk from infected cows. The tubercle bacillus of cat- 
tle and of hogs (the “bovine type ”) of the germ can 
grow in the human body. It attacks children much 
more frequently than it does older persons, and it usu- 
ally grows in the bones, in glands, or in the walls of the 
intestine, rather than in the lungs. 
Tubercle bacilli in milk. The tubercle bacillus may 
at times get into the body from meats, but infection 
from milk is much more important. Where the disease 
is allowed to run uncontrolled, from 15 to 30 per cent 
of dairy cattle have the disease, and from 5 to 9 per 
cent of the unpasteurized milk sold in certain of our cities 
has been found to contain living tuberculosis germs. 
Danger from the bovine type of the tubercle bacillus. 
The bovine variety of the tubercle bacillus is fitted for 
growth in the body of the cow rather than in the human 
body, and it is believed to be much less virulent for 
man than is the “ human type ” of the germ that is 
usually found in the sputum of a consumptive. The 
question of tuberculosis among cattle is an important 
one, however; for 10 per cent of all deaths from tuber- 
culosis among children under five years of age are due 60 
PRIMER OF SANITATION' 
to the bovine type of the germ, and many thousands of 
other persons are being infected by these germs each 
year. A very simple and certain method of testing 
cattle for tuberculosis has been discovered, and even 
if there were no danger of man’s getting the disease 
from milk, tuberculous cattle should be separated from 
those that are free from the disease. This is economy; 
for by taking out of a herd all the animals that have tu- 
berculosis, the spread of the disease in the herd can be 
stopped. Milk from a dairy that is not known to be free 
from tuberculosis should be Pasteurized before it is used 
(page 156). 
POINTS TO BE REMEMBERED 
1. Tuberculosis costs the United States 150,000 citizens each 
year, and it is estimated that its annual cost in money is 
$ 1,000,000,000. 
2. The tubercle bacillus is slow-growing, but it is very difficult 
to kill. 
3. In tuberculosis any part of the body may be attacked, but 
consumption is by far the worst form of the disease. 
4. The germs enter the body either by being inhaled or by 
being swallowed. 
5. They withstand drying and are scattered in many ways. 
6. The sputum of consumptives is full of germs, and it should 
be burned or disinfected. 
7. Most cases of consumption are contracted by contact infec- 
tion, and a careless consumptive is dangerous to those about 
him. 
8. The tubercle bacilli that are often present in milk are dan- 
gerous to man. 
9. Milk that may contain tubercle bacilli should be Pas- 
teurized. CHAPTER FOURTEEN 
THE TREATMENT OF CONSUMPTION 
The steady manner in which consumption often runs 
on and on has caused many persons to think that it is 
an incurable disease. This is a great mistake. In very 
many persons who become infected in early life the 
germs are walled off and held dormant in the lymphatic 
glands or other parts of the body, and it is a very common 
occurrence for the tubercle bacillus to start its growth in 
the lungs and to be checked by the body without the 
person who is being attacked ever knowing what is 
happening. If consumption is taken in hand before 
the germs have gained a secure foothold, it yields to 
treatment much more readily than many other bacterial 
diseases. 
The importance of early treatment. In the treatment 
of consumption, everything depends on beginning in the 
early stages of the disease (Fig. 44). One who has 
symptoms1 of consumption, therefore, should not try to 
persuade himself that his symptoms have no existence, 
for this will not stop the growth of the germs. He should 
not lose valuable time experimenting with patent medi- 
1 The most common symptoms of consumption are cough, loss of appe- 
tite, gradual loss of weight and strength, fever in the afternoon, night 
sweats, and blood spitting. The cough may be absent in the very early 
stages of the disease, or it may be troublesome only in the early morning 
and after going to bed at night. Any one who loses weight or finds him- 
self becoming tired easily, should have himself examined at once, even 
though he have no cough. By writing to the Secretary of the State Board 
of Health at the capital of his state, or to the State Society for the Pre- 
vention of Tuberculosis, a consumptive can obtain helpful literature and 
trustworthy advice. In many cities and counties public dispensaries are 
maintained to which any one who wishes advice about tuberculosis may go 
61 62 
PRIMER OF SANITATION 
cines, for there is no medicine known that will cure con- 
sumption. The only sensible thing for him to do is to 
be examined at once by a physician who thoroughly 
understands the disease. Then, if he finds that the 
Fig. 44. The amounts of white in A, B, and C show the chances that a con- 
sumptive in the early, moderately advanced, and advanced stages of the disease 
has of being cured or of having his disease arrested. These figures are from the 
experience of the State Sanatorium at Rutland, Massachusetts. From 1889-1907 
this institution treated 1911 persons who were in the early stages of consumption, 
and in 1450 of them the disease was apparently cured or arrested. Of moder- 
ately advanced cases 16x6 were treated, and in 604 of them the disease was ap- 
parently cured or arrested. Of more advanced cases 784 were treated, and in 
only 147 was the disease apparently cured or its progress stopped. These figures 
show the very great importance of early treatment of the disease. 
germs have gained a foothold in his lungs, he should 
give himself the best possible treatment without delay. 
Important factors in treatment. In the successful 
treatment of consumption, the following are the more 
important factors : — 
Rest. If a consumptive can be kept quiet, much of 
the toxin that is produced by the germs will be thrown 
off in the sputum. Anything that causes the breathing 
to be quickened and deepened causes more of the toxin 
to be carried from the lungs through the body, and in- 
creases the fever. 
A consumptive should therefore have rest. If he has THE TREATMENT OF CONSUMPTION 
63 
fever, he should have absolute rest, not even walking 
about his room. Laughing and loud talking should be 
avoided, and coughing should be refrained from as much 
as possible. When there is no fever, a little exercise 
may be taken, but it should be 
taken with care. 
Food. A consumptive should 
have an abundance of nourish- 
ing food, especially of fatty 
food. Meat, eggs, milk, and 
any other good foods that he 
can eat and digest should be 
taken. Lunches should be eaten 
between meals and on retiring. 
The foods must be well pre- 
pared and served in different 
ways, or the patient will become 
•tired of them. “ Stuffing ” a 
patient, however, may cause in- 
digestion, and the diet of a con- 
sumptive should be looked after 
carefully. 
Outdoor life. Nothing in the treatment of consump- 
tion is more important than fresh air, and the disease has 
been most successfully treated when the patients have 
lived and slept in the open air, summer and winter. 
Often an upper porch can be arranged as a sleeping 
place. In outdoor sleeping in winter, it is necessary to 
have warm clothing and to wear some kind of hood to 
protect the head and neck, and in many places in sum- 
mer it is necessary to screen the patient from mosquitoes. 
Other important points. Warm and dry clothing is of 
Fig. 45. An outdoor sleeping 
place, of a kind that most con- 
sumptives can have. 64 
PRIMER OF SANITATION 
course important. Sunlight on the skin increases the 
number of white corpuscles in the blood and is used in 
the treatment of tuberculosis, but too much exposure to 
light is injurious, and the advice of a physician is needed 
Fig. 46. Consumptives taking the winter air on a city roof. 
in taking the light treatment. A consumptive should 
not remain in a damp house. 
Finally, every consumptive should have a skilled 
physician to watch over and guide him in his treatment 
of himself, and he should secure some of the many books 
and circulars that have been written on consumption and 
its treatment, and learn how to live in a way that will 
give the best possible chance for recovery.1 He should 
1 Hawes’s Consumption: What It Is and What to Do About It (Small, 
Maynard & Co., Boston) is an excellent little book for consumptives. Brown’s 
Rules for Recovery from Pulmonary Tuberculosis (Lea & Febiger, Phila- THE TREATMENT OF CONSUMPTION 
65 
always think of the safety of others and should take care 
not to endanger those about him. He should be cheer- 
ful and hopeful, for if he takes his disease in time he has 
every reason to expect recovery. 
Fig. 47. Window tents can be bought that allow a consumptive to obtain fresh 
air through an open window while his body remains in bed in a warm room 
This tent was designed by Dr. S. A. Knopf. 
The effect of climate on consumption. It was formerly 
supposed that climate was very important in the treat- 
ment of consumption, but in all our states consumptives 
are now being cured, and it has been found in treating 
this disease that rest, food, and fresh air are of much 
more importance than climate. Unless a consumptive 
delphia) is authoritative and most helpful in mastering the details of the 
treatment. The Journal of the Outdoor Life, New York City, is invaluable 
to consumptives. It contains advertisements of sanatoria and of clothing, 
chairs, and other articles used by consumptives. 66 
PRIMER OF SANITATION 
has money enough to support himself without work and 
to give himself proper care, he should not leave his home 
for a distant state. For in many places consumptives 
are not welcomed, and 
it is better to be at 
home and have the 
proper care than to be 
without money orfriends 
in the best climate in 
the world. In general, 
a cold, dry climate is 
best for consumptives, 
and they should avoid 
hot, moist climates and 
high elevations. 
Sanatoria for con- 
sumptives. Many 
states have established 
sanatoria to which con- 
sumptives can go and, 
at a slight expense, re- 
main until they recover 
from the disease. This is sensible, for in a sanatorium a 
consumptive can have proper food and care at much 
less expense than he can have them at home, and in 
sanatoria the spread of the disease is stopped. It is 
much more economical for the people of a state to 
care for their consumptives in sanatoria than out of 
them, and it is much pleasanter and better for the pa~ 
tients. In checking the spread of tuberculosis, sanatoria 
have been a wonderful help — perhaps a greater help 
than any other one thing. 
Fig. 48. Diagram showing the tubercu- 
losis death rate in Massachusetts since 1851 
for each 100,000 inhabitants. THE TREATMENT OF CONSUMPTION 
67 
Inheritance and consumption. Consumption is often 
spoken of as an inherited disease, and it is true that 
some families are more afflicted by it than are other 
families. This does not 
mean that children in these 
families are born with tuber- 
culosis germs in their bodies, 
but it means that they are 
born with less power of 
killing these germs than 
most people have. People 
who come of consumptive 
families cannot have con- 
sumption unless they get 
tubercle bacilli into their 
lungs} and if they can avoid 
the germ, they may be as 
well and strong as any one. 
It should be understood 
that persons who move into 
houses that are infected with 
tubercle bacilli often con- 
tract the disease, although 
there may be no history of 
consumption in their fami- 
lies. 
Hygiene and tuberculosis. A quick disease like meas- 
les or smallpox cannot be prevented by hygienic living; 
Fig. 49. This diagram shows the 
gradual decrease in the number of 
deaths from tuberculosis in the United 
States. The numbers given are the 
deaths per 100,000 in the part of the 
United States where statistics have 
been carefully kept. 
1 A tendency to consumption may be inherited, just as a tendency to 
drunkenness may be inherited. But without whisky or other alcoholic 
drinks we can have no drunkenness, and without the tuberculosis germ we 
can have no consumption. —Dr. Ennion G. Williams. 68 
PRIMER OF SANITATION 
the germs attack so rapidly that the disease is on in full 
force before the body has time to manufacture sub- 
stances to kill them. In tuberculosis the situation is 
very different. The body has plenty of time to work 
up its defenses, and 
even where the germs 
have begun to grow in 
the body they are 
checked and held in a 
harmless condition in 
the great majority of 
cases. It follows, 
therefore, that right 
habits of living and 
improving the condi- 
tions under which we 
live are a part of the 
fight against the dis- 
ease. From 15 to 30 
are the years when 
consumption is most common, and during this time of 
life special care should be used to keep the resistance of 
the body high. One important fact to remember is that 
after attacks of diseases like measles or typhoid fever 
the body needs special care until health and strength 
have returned in full. 
Progress in the prevention of tuberculosis. As we 
have seen, no germ has so spread itself through all so- 
ciety and has so extended its ravages to all parts of the 
world as has the tubercle bacillus. Yet the world is not 
full of tubercle bacilli. The air of the fields and woods, 
the streams of the forests and mountains, and the soil of 
Fig. 50. This diagram shows the decrease 
in deaths from tuberculosis in England and 
Wales. THE TREATMENT OF CONSUMPTION 
69 
the fields, are free from them. The millions of people 
who in the past have died of tuberculosis germs got these 
Fig. 51. Tent sanatorium for consumptives of the Modern Woodmen of 
America at Colorado Springs, Colorado. (After a photograph.) 
germs from either sick cattle or sick men. Practically 
all the millions of people now living who are carrying 
these germs in their bodies were infected either by 
human sputum or by milk. Some persons, some cities, 
some states, and some nations have to a greater or less 
degree known these facts for some years, and in some 
places a warfare on the Great White Plague has been 
started. This warfare has been most successful. Ex- 
amine Figure 48 and you will see that not one third so 
many people are now dying of tuberculosis in Massa- 
chusetts as died of it in that state sixty years ago. Ex- 
amine Figure 49 and you will see that what is true of 
Massachusetts is true also, to a great extent, of other 
parts of the United States; and Figure 50 shows that 
not only in our own country but also in other countries 70 
PRIMER OF SANITATION 
has this great enemy of mankind been checked. 
“Tuberculosis is communicable, preventable, and cur- 
able,” is the battle cry of the anti-tuberculosis host, and 
in that host hope swells high in every breast, for already 
in many places the battle line of the enemy has been 
broken, and his forces are being driven back. Much of 
the work that is being done has as yet hardly begun to 
show its effects, but the results prove clearly that it is 
not necessary for people to die of tuberculosis as they 
are dying now. 
POINTS TO BE REMEMBERED 
1. In curing consumption, the most important point is to begin 
treatment in the very early stages. 
2. In its early stages consumption is curable. 
3. Rest, food, and fresh air are the important factors in the 
treatment of the disease. 
4. Climate is not so important in the treatment of tuberculosis 
as was formerly supposed. 
5. Sanatoria are to be recommended because in them the 
patient can have the care that he needs, and in them there 
is no danger of the spread of the disease. 
6. The germ of tuberculosis is not inherited, but some persons 
do inherit only a slight resistance to the germ. 
7. A person who belongs to a consumptive family should take 
especial care to avoid the germ and to keep up his health. 
8. Great progress has been made in the war against tuber- 
culosis, and those who are fighting the disease are very 
hopeful for the future. CHAPTER FIFTEEN 
DUST AND GERM DISEASES 
In a cubic yard of ordinary air there are from a hun- 
dred to a thousand bacteria. These bacteria are cling- 
ing to particles of floating matter of one kind and 
another; for they themselves are heavier than air, and 
by themselves they would fall to the earth like little 
stones. Air that is free from dust is therefore free 
from bacteria also, and by stirring up dust the number 
of bacteria in the air can be increased to a multitude. 
How very abundant small floating particles are in the 
air may be seen when a ray of sunshine enters a dark- 
ened room through a narrow opening. 
Disease germs in dust. People who are forced to 
breathe dusty air always suffer greatly from sore throats, 
catarrh, bronchitis, pneumonia, and consumption. It 
was formerly believed that these diseases were air-borne, 
but later studies have shown that, generally speaking, 
the bacteria in the air are of harmless varieties; that 
disease germs die when they are exposed to light or 
thorough drying, and that dust under ordinary con- 
ditions is not an important carrier of germs. Neverthe- 
less, it is true that in a weak light germs may remain 
alive in sputum or in mucus from the nose until these 
discharges are dry enough to be powdered up and 
blown about in the air. We cannot, therefore, say that 
indoor dust, such as is stirred up by sweeping a school- 
room, is always free from germs. 
How germs get into dust. Practically all the disease 
germs that are in dust have been spit into it by human 
beings. If you will count up the dangerous germs that 
may be in saliva (the germs of consumption, pneumonia, 
71 72 
PRIMER OF SANITATION 
influenza, diphtheria, catarrh, bronchitis, colds, meningi- 
tis, infantile paralysis, whooping cough, scarlet fever, 
and measles), you will understand at once why every 
one should refrain from spitting on floors and in public 
Fig. 52. In a light and well-ventilated room germs are killed by the light 
and drying. 
places, especially in places where the sunlight has not 
an opportunity to kill the germs.1 
The greatest danger from dust. Dust is dangerous 
chiefly, not because it carries germs into the air pas- 
sages, but because it wounds the lining of the air pas- 
sages and allows the germs that have already gotten 
into these parts in other ways to set up their growth. 
That this is the most important effect of dust is shown 
by the fact that dust that is absolutely free from germs, 
like that breathed in by stone cutters or metal grinders, 
causes those who breathe it in to suffer from respiratory 
diseases. Dust itself is, therefore, a cause of disease, 
1 According to the newer ideas of sanitation the chief danger in spit- 
ting lies in the fact that the germs in the fresh sputum are often carried 
about until they reach the hands and food of other persons. DUST AND GERM DISEASES 
73 
and everything possible should be done to keep it from 
flying in the air. 
Keeping down dust. Streets should be sprinkled, and 
where it is possible they should be cleaned by washing 
instead of by sweeping them. Houses should be swept 
with carpet sweepers or damp brooms, and some damp 
material should be used in 
sweeping schoolrooms and other 
public buildings.1 Schoolrooms 
should be swept after school, 
so that there will be time for 
the dust to settle before the 
pupils assemble the next morn- 
ing, and other public buildings 
should be swept some time be- 
fore they are to be used. Dust- 
ing should be done with a damp 
cloth that will wipe off the dust 
and take it away, for it is simply 
foolish to stir up the dust into the air, where it will 
be inhaled or will settle again on objects in the room. 
In rooms that are much used, hard floors, rugs, and 
FlG- 53- The wrong way to re- 
move dust from furniture. 
aThe Michigan State Board of Health recommends the following prep- 
arations for use in sweeping the floors of public buildings: — 
(1) To a pailful of sawdust wet with hot or cold water add one half 
pint of kerosene and a tablespoonful of sulpho-naphthol or formaldehyde. 
(2) Heat one third part sand, and add two thirds part sawdust. To a 
pailful of this mixture add one half pint of paraffin oil (kerosene may be 
used) and mix thoroughly. This preparation produces excellent results. 
(3) Boil one pound of sal soda and one pound of chlorid of lime 
(bleaching powder) in a gallon of water. Dampen sawdust to be used 
for sweeping with this solution. This preparation is excellent for restor- 
ing the natural color of floors. 74 
PRIMER OF SANITATION 
plain furniture are more hygienic than heavy carpets 
and plush-covered furniture, because it is easier to keep 
them free from dust. Vacuum cleaners are recom- 
mended by health officials, because they remove dust 
and do not stir it up where it will be breathed into the 
lungs. 
Preventing dust in manufacturing processes. Dusty 
trades (for example, pottery, metal grinding, stone cut- 
ting, and cotton weaving) are exceedingly unhealthful, 
and in some of these trades respiratory diseases (es- 
pecially consumption) claim a majority of the workers 
unless measures are taken to guard against the breath- 
ing in of the dust. In some of the processes, the work- 
man protects himself by wearing a mask, while streams 
of water used to keep down the dust and air blasts ar- 
ranged to carry the dust away are each year saving 
hundreds of workers from death by diseases of the air 
passages and lungs. It is right that the workers in 
these trades should be protected; for dust, whether it 
be in the home,.school, or factory, is a cause of disease. 
POINTS TO BE REMEMBERED 
1. Bacteria are in the air only when floating matter or dust 
is in the air. 
2. People who are forced to breathe dust suffer from respira- 
tory diseases. 
3. Indoor dust may contain disease germs. 
4. The disease germs in dust come from the sputum of 
human beings. 
5. Dust is dangerous chiefly because it wounds the walls of 
the air passages and allows germs to start their growth. 
6. Every possible effort should be made to keep down dust. CHAPTER SIXTEEN 
THE ALIMENTARY CANAL 
The alimentary canal is a long passageway through 
the body. Its principal divisions are the mouth, 
throat, esophagus, stomach, small intestine, and large 
intestine. Like the air 
passages, the alimen- 
tary canal opens to 
the outside world and 
germs, therefore, eas- 
ily enter it. The 
juices of the stomach 
contain an acid that 
keeps most bacteria 
from growing in that 
part of the alimentary 
canal, but in the long 
reaches of the small 
intestine a number of 
germs grow and cause 
disease. 
Bacterial diseases of 
the intestine. Among 
bacterial diseases of 
the intestine are typhoid fever, cholera, dysenrery, diar- 
rhea, and meat poisoning. This group of diseases 
causes yearly in the United States over 100,000 
deaths, or about one thirteenth of all the deaths 
that occur; and of these 100,000 deaths about 70,00c 
are among children under two years of age. It should 
be understood that intestinal diseases are much more 
easily prevented than are respiratory diseases, for the 
liver 
esophagus 
stomach 
large 
intestine 
small 
intestine 
Fig. 54. The alimentary canal. 
75 76 
PRIMER OF SANITATION 
germs in most cases leave the body only in the intes- 
tinal wastes. 
Food poisoning. Food poisoning is sometimes caused 
by bacteria of the typhoid group (page 82), but in our 
country it is usually due to a soil bacillus that is a rel- 
ative of the tetanus germ. It gets into meat, fish, and 
canned vegetables and fruits, and, since it forms spores 
that are not killed except by considerable steam pressure, 
fruits and vegetables canned after being merely boiled 
may still be infected by it. It produces a most violent 
toxin, and it is the toxin that has been formed in the food 
before it is eaten, and not the germs, that does the 
damage. The toxin is destroyed by boiling, and any 
canned food that seems spoiled in the least should be 
cooked before it is even tasted, for death has followed 
tasting a spoonful of spoiled corn or “nibbling” a spoiled 
bean pod. Symptoms of the poisoning do not usually 
appear for from one to four days. Among the symptoms 
are great weakness, blurred vision, and paralysis of the 
throat. Limberneck in chickens is due to eating food 
infected by this same bacillus, and it is reported that 
forage poisoning (“blind staggers ”) in horses is caused 
by feeding hay and ensilage in which it has grown. 
An antitoxin has been prepared. 
1. Intestinal diseases cause more than 100,000 deaths in the 
United States each year. 
2. These diseases attack children especially. 
3. The germs are spread in the body wastes. 
4. Most cases of food poisoning are due to toxin from a bacillus 
that grows in foods. 
POINTS TO BE REMEMBERED CHAPTER SEVENTEEN 
TYPHOID FEVER 
Typhoid fever is found in all climates and in all coun- 
tries where man dwells. It is usually a severe dis- 
ease, but during some cases (“ walking 
typhoid ”) the patient is hardly ill 
enough to go to bed. In the United 
States it is rapidly decreasing, but it 
still causes more than 15,000 deaths 
each year. The incubation period is 
from seven to twenty-one days. 
Typhoid fever an important disease. The importance 
of typhoid fever is not shown by the number of deaths 
that it causes. For every person who dies from typhoid 
fever there are six or seven others who must be watched 
over through the anxious weeks of an attack, and of 
these a considerable number rise from their sickness 
with weakened kidneys, lame backs, crippled limbs, or 
other injuries that last through life. There are at least 
200,000 cases of this disease in the United States each 
year. 
The typhoid germ. The germ of typhoid fever is a 
plump bacillus. It is fitted to live in a liquid, and 
swims freely. It enters the body through the mouth 
and attacks especially the walls of the small intestine, 
but in cases of typhoid the germ is found in the blood 
and all through the body. Meningitis, pneumonia, and 
ulcers in the bones are caused by this germ, and the 
“ rose spots ” that appear on the abdomen in most cases 
of typhoid fever are caused by the germs growing 
in the skin. The germs leave the body in the discharges 
Fig. 55. The typhoid 
germ. 
77 78 
PRIMER OF SANITATION 
from the bowels and kidneys,1 and occasionally in mat- 
ter vomited by a typhoid patient. They may be in the 
perspiration, and if they are growing in the 
lungs, they will be found in the sputum. 
The typhoid germ outside the body. The 
typhoid germ is not known to attack animals. 
It can live in water for several weeks, and in 
the soil it is thought that it lives for several 
months. It multiplies rapidly in milk. Drying 
quickly kills it, and in general, typhoid germs 
usually die soon after they leave the human 
body. Typhoid victims are therefore persons 
who have taken into their mouths typhoid germs 
that not long before left the body of some one else. 
How typhoid fever is contracted. Persons in 
the same house with a 
typhoid patient may get 
the germ on their hands 
by handling bedding or 
in a hundred other ways. 
Flies will carry the germs 
in great numbers if all 
wastes from a typhoid 
patient are not carefully 
destroyed. Occasionally 
the germs are in oysters 
that have been grown in polluted waters, and for this 
reason cooked oysters are safer than raw ones. In a 
Pittsburg 
New York City 
London 
Fig. 56. Diagram showing the num- 
ber of deaths from typhoid fever for each 
100,000 inhabitants in Pittsburg, New 
York, and London in 1907. At that time 
the people of Pittsburg were drinking 
the polluted Ohio River water, New York 
had a good water supply, and London 
was using Thames River water filtered 
through beds of sand. 
1 In about 25 per cent of typhoid cases, the germs are in the urine, 
sometimes in enormous numbers (100,000,000 to 500,000,000 in a cubic 
centimeter, or 5,000,000 to 25,000,000 in a single drop). This must be 
carefully disinfected, or it will prove a most dangerous source of infection* TYPHOID FEVER 
79 
large number of cases, the typhoid germ has been 
carried in milk where some one having the disease has 
handled the milk, or where the milk ves- 
sels have been washed in water contain- 
ing the germs.1 In many other cases 
typhoid is contracted from water. In 
a later chapter we shall discuss the sub- 
ject of disease germs in drinking water 
(page 86). 
Germ carriers. It has been found that 
a considerable number of persons who 
have had typhoid carry the germs long 
after recovery from the disease. The 
germs usually locate themselves in the gall 
bladder and keep on passing into the 
intestine. One cook in New York gave 
the disease to twenty-seven persons in 
five years ; a cook in Richmond, Virginia, 
gave the disease to ten persons in four 
widely separated houses. In one case the 
germs were found in the discharges from 
the body forty-two years after recovery 
from the disease. As yet it has not been 
possible to free these persons from the 
germs, and they are a constant source of danger to all 
about them. 
Fig. 57. in 1895 
Chicago ran its 
sewage into Lake 
Michigan, from 
which its water 
supply was ob- 
tained. A drain- 
age canal now car- 
ries most of the 
sewage away from 
the lake. The di- 
agram shows the 
decrease in the 
death rate from 
typhoid fever, fol- 
lowing the im- 
provement of the 
water supply. 
1 In 1907 a case of typhoid fever occurred in a mountain house near 
Palo Alto, California. The wastes from the patient were thrown into a 
stream on which a dairy was located some distance below. The milk cans 
at the dairy were washed in the stream, and a typhoid epidemic of 236 
cases developed among the people who were supplied with this milk. Ir* 
the spring of 1908 one milkman in Boston who was suffering with typhoid 
caused an epidemic of over 400 cases. 80 
PRIMER OF SANITATION 
The prevention of typhoid fever. The great preven- 
tives of typhoid fever are pure water, pure milk, a safe 
method of disposing of human sewage, destroying care- 
fully the germs that come from the bodies of typhoid 
fever patients and others who are carrying typhoid 
germs, removal of the breeding places of flies, and vac- 
cination. In small villages and on farms, the great cause 
of typhoid fever is leaving human wastes exposed to flies 
(page 192). Vaccination against typhoid fever is now 
extensively practiced in armies, hospitals, communities 
where the disease is unusually prevalent, and among 
those who for any reason may run an unusual risk of 
being exposed to the disease. By vaccination the dis- 
ease can be almost entirely prevented, and some health 
officers advise anti-typhoid vaccination for the whole 
population. 
POINTS TO BE REMEMBERED 
1. There are annually at least 200,000 cases of typhoid fever 
in the United States. 
2. All cases of typhoid are caused by germs that have come 
from the human body. 
3. The germs enter the body through the mouth, very fre- 
quently in water. 
4. Some persons carry the germs long after they have recov- 
ered from the disease. 
5. Pure drinking water, proper disposal of sewage, destroying 
all wastes that contain typhoid germs, and the removal of 
the breeding places of flies are the great factors in the pre- 
vention of typhoid. 
6. Vaccination against typhoid fever is now successfully prac- 
ticed. CHAPTER EIGHTEEN 
DISEASES CAUSED BY RELATIVES OF THE TYPHOID GERM 
The causes of some of the germ diseases of the in- 
testine are not well understood, as so many different 
bacteria are found growing in the intestine that it 
is sometimes impossible to be sure which one is 
causing the trouble. Among the germs frequently found 
in the intestine are several that are closely related to 
the typhoid bacillus. In this chapter we shall study 
some of the more important and best-known of these 
germs. 
The colon bacillus. The colon bacillus is very much 
like the typhoid bacillus. It is always found in the in- 
testine of man and of all the higher animals. Usually it 
feeds on the contents of the intestines and does no harm, 
but when the body is weakened (as by hot weather), 
or perhaps when a more powerful race of the germs gets 
into the intestine, the colon bacillus seems to be a cause 
of diarrhea and other troubles. 
The bacillus of dysentery. Chronic dysentery is caused 
by a protozoon; this disease we shall study in a later 
chapter (page 131). The sudden attacks of acute dysen- 
tery, which sometimes run in epidemics, are caused by a 
bacillus that differs very little from the typhoid bacillus.1 
This is a severe disease, and one that is greatly feared 
by armies. In different parts of the United States 
there are epidemics of it every summer. The germs are 
scattered in the same ways that typhoid germs are 
scattered, and because the disease is a very dangerous 
one, all matter from a dysentery patient should be 
carefully destroyed. 
1 Acute dysentery is often called flux. 
81 82 
PRIMER OF SANITATION 
Illness from germs of the typhoid group in foods. One 
form of meat poisoning is due to a bacillus of the typhoid 
group that causes illness in cattle; horses, hogs, and goats. 
The germ is in the flesh before the animal is killed, and 
the flesh of sick animals should not be used as food. 
Meat infected with this germ has no odor and does not 
appear to be spoiled. 
Many of the sudden outbreaks of diarrhea and intes- 
tinal trouble that are due to foods are believed to be due 
to other relatives of the typhoid germ. Sometimes they 
get into the food from people, but it is known that ani- 
mals like the dog, cat, rat, and mouse carry germs of this 
group and it is believed that food is sometimes infected 
by these animals. 
Rats in particular are unclean, destructive, and in- 
sanitary animals (pages 205 and 206), and they should 
not be allowed about human habitations or where human 
foodstuffs are kept. Directions for rat-proofing build- 
ings may be obtained from the United States Depart- 
ment of Agriculture or from the United States Public 
Health Service. 
POINTS TO BE REMEMBERED 
1. The colon bacillus is always found in the intestine and at 
times causes mild forms of disease. 
2. Acute dysentery is caused by a bacillus that is a relative of 
the typhoid germ. 
3. Food may contain dangerous germs of the typhoid group. 
4. Germs of this group are carried by animals, and it is believed 
that food sometimes becomes infected from animals. CHAPTER NINETEEN 
OTHER BACTERIAL DISEASES OF THE INTESTINES 
Diarrhea and inflammation of the intestine are im- 
portant causes of death, especially among young children. 
All together these troubles cause in our country over a 
Fig. 58. In the Federal armies, during the four years of the Civil War, 110,07c 
soldiers were killed in action or fatally wounded. During the four years from 
1903-1907, in the United States, 271,773 children under two years of age died 
from diarrhea and other similar diseases. The height of the child and the 
height of the soldier show the relative number of deaths in each case. 
hundred thousand deaths a year. They are most to be 
feared in the summer, the time when children are weak- 
ened by the heat, and the time when germs multiply 
most rapidly in water and in foods. The germs enter the 
body in water, milk, and other foods. Flies are espe- 
cially responsible for the spread of these diseases. 
Germs that cause diarrhea. It seems probable that 
any one of several different kinds of bacteria may cause 
83 84 
PRIMER OF SANITATION 
diarrhea and inflammation of the intestine. In some 
cases pus-forming bacteria (sometimes streptococcus, 
sometimes Bacillus pyocyaneus) seem to be the guilty 
germs. In other cases it is probably the colon bacillus. 
Probably mild attacks of typhoid fever and dysentery 
are sometimes mistaken for simple diarrhea. The dis- 
ease is infectious, and germs from a sick person should 
be destroyed. 
Weak and strong races of intestinal germs. It is 
probable that among the germs that commonly grow in 
the intestine there are different races, some more pow- 
erful than others. It is also probable that new races of 
these germs give us more trouble than those to which 
we are accustomed; for water that does not seem to 
trouble those who use it daily will often start intestinal 
disturbances in visitors and travelers. This is probably 
because those who drink the water from day to day 
become accustomed to the germs in it and their systems 
learn to resist them, while a stranger is not prepared to 
overcome germs of these particular races. 
Cholera infantum, or summer complaint, in children. 
It has not been possible to prove that any one germ is 
the cause of cholera infantum. In a number of epi- 
demics the bacillus of dysentery has been discovered, 
but in many cases other germs seem to be the cause. 
The trouble seems to be that in summer babies are 
weakened by the heat until they have little resistance to 
germs, and at the same time the milk which is fed to 
babies is kept warm until it swarms with multitudes of 
bacteria of many different kinds. To prevent cholera 
infantum the milk must be kept clean and cold, and it 
should be used as fresh as possible. The milk vessels OTHER DISEASES OF THE INTESTINES 
85 
and the bottles should be thoroughly washed and 
scalded to kill germs that are on them, and no impure 
water that: is likely to contain 
germs capable of causing 
diarrhea should ever be given 
to a little child. 
Indigestible foods that will 
lie in the intestine and form a 
breeding place for germs 
should not be given to young 
children. Children should be 
given all the fresh air possible, 
and their general health should 
be built up in every way, so 
that they will be able to resist 
germs. It should be remem- 
bered that cholera infantum is 
infectious, and any person who 
is caring for a little baby should keep the baby away from 
the disease. Isolating the patient and disinfecting the 
body wastes has proved one of the most effective 
methods of checking the spread of the disease. 
Fig. 59. The wrong kind o5 
nursing bottle and the right kind. 
The bottle with the long, slender 
tube and the narrow mouth is 
hard to keep clean; the bottle 
with the wide mouth may be 
cleansed easily. 
POINTS TO BE REMEMBERED 
Diarrheas are caused by several different germs. 
2. It is probable that there are weak and strong races of these 
germs. 
3. Cholera infantum is generally caused by germs in milk. 
4. Babies should be carefully looked after, so that they will be 
able to resist the germs of intestinal diseases. 
5. Diarrheas and cholera infantum are infectious. CHAPTER TWENTY 
DISEASE GERMS IN WATER 
The disease germs that are most common in water 
are the germs of intestinal diseases. We shall therefore 
consider the question of a pure water supply. The im- 
portance of this subject is often not appreciated, for 
many people neither realize the great number of deaths 
that are due to impure water nor understand that it is 
possible to prevent most of these deaths. 
The importance of a pure water supply. By filtering 
their water supplies through beds of sand, Albany, New 
York, and Lawrence, 
Massachusetts, have 
saved two thirds of the 
people who would have 
died of typhoid fever, 
if they had continued 
drinking impure water. 
Niagara Falls installed a 
water-purifying plant, 
and five years later its 
death rate from typhoid 
was only one eighth of 
what it had been when 
polluted river water was 
used. Certain towns in 
the Philippine Islands now use artesian water, and in 
those towns there are only about one half as many 
deaths as there were when impure water was used. 
Germ diseases that are contracted from water. The 
diseases that are most frequently contracted from water 
are cholera, typhoid, dysentery, and diarrhea. The 
Fig. 6o. For many years Pittsburg 
had the highest death rate from ty- 
phoid fever of any of the large cities 
of America. Can you tell why? 
86 DISEASE GERMS /AT WATER 
87 
jrms of these diseases come from the bodies of human 
beings, reach water that is used for drinking purposes, 
and get back to the human mouth. In our country, 
typhoid fever is the most important of the water-borne 
diseases, although in the southern half of the United 
States dysentery and diarrheas are widespread and 
serious diseases. 
Not only are the deaths from typhoid and other in- 
testinal diseases reduced by using pure water, but for 
some reason a marked decrease in the number of deaths 
from pneumonia, tuberculosis, and several other diseases 
seems to follow changing from impure to pure water. 
The reason for this decrease is not yet fully understood. 
It is known, however, that in pneumonia, influenza, 
diphtheria, and tuberculosis the germs are practically 
always in the wastes from the alimentary canal, and 
tubercle bacilli have been found in the water of a stream 
that received the drainage of a tuberculosis sanatorium. 
It seems probable that the germs of respiratory diseases 
live in water and that many persons contract these dis- 
eases through impure drinking water. 
How disease germs get into drinking water. Usually, 
disease germs either get into water from sewage or are 
washed into the water from soils that have been polluted 
with wastes from the human body. They may get into 
a well or cistern if a person who has germs on his 
hands works around the pump or handles the water 
buckets; a stream may be polluted by washing clothes 
from a diseased person in it, or by a diseased person 
bathing in it; but in general, disease germs are washed 
out into waters from polluted soil. The following history 
of the typhoid epidemic that occurred in Plymouth, 88 
PRIMER OF SANITATION 
Pennsylvania, in 1885, shows how the water supply of a 
town may be infected with germs. During the winter of 
1884-85, a man living on the bank of a stream that 
flowed into the town reservoir was stricken with typhoid 
fever. The wastes were thrown out on the snow, and 
in the spring the waters from the melting snows and the 
rains washed these germs into the water supply of the 
town, and typhoid fever suddenly broke out. The city 
had a population of about 8000, and during the height 
of the epidemic from 50 to 200 persons a day were 
attacked. All together there were 1104 cases and 114 
deaths. People who drank from wells escaped, and there 
is no doubt that the germs came from the public water 
supply. 
Epidemics like the one in Plymouth are, of course, 
uncommon, but if you will investigate you will probably 
find that in the town or community in which you live, 
several persons die each year from diseases that are 
mainly due to water. 
Dangerous waters. Any water that comes from the 
surface of the ground is likely to contain disease germs. 
Shallow wells, springs, and small streams are the most 
dangerous of all waters. It is not safe to use water from 
these sources, no matter how clear and pure it may 
seem; for in the country, where people drink chiefly 
from wells, typhoid fever is more common than it is in our 
most crowded cities, and in the mountain regions, where 
the people drink from the most beautiful clear springs 
and streams, typhoid is a great scourge. Experience 
shows that intestinal diseases follow the drinking of 
surface water, and it is not the part of wisdom to fail to 
profit by the experience of those who have lived before us. DISEASE GERMS IN WATER 
89 
Safe waters. In general, waters that do not come from 
the surface of the ground are safe. Deep artesian wells 
(except in rare instances in mountain regions) furnish 
water that is absolutely safe. Rain water that is caught 
and stored away in tanks above the ground is safe also. 
There is a common idea that dangerous germs may be 
blown up on a roof in dust, but the germs of intestinal 
diseases die if they are thoroughly dried, and are not 
found in rain water that has been kept from touching 
the ground. Underground cisterns that are thoroughly 
cemented are much safer than wells. Yet there is 
danger of ground water getting into a cistern around the 
top, or if part of the pipe that carries the water from 
the roof is underground, germs may easily get into the 
cistern through this pipe. There is also danger of germs 
falling into an underground cistern from the platform 
above. Distilled water is perfectly safe, but some bottled 
spring waters contain bacteria. 
Keeping germs out of wells. In country regions wells 
will probably be the principal source of drinking water 
for many years, and it is important that they be made as 
safe as possible. In guarding a well from dangerous 
germs, the following are the chief precautions to be 
taken : — 
Keeping surface water out of wells. Very few bacteria 
live deeper than three or four feet in the ground, and 
water, as it comes from the ground into a well that is as 
much as twenty feet deep, is usually free from germs. In 
most cases the pollution of the water in such a well 
comes from the surface water getting into the well 
when it rains and carrying with it germs from the upper 
layers of the soil. 90 
PRIMER OF SANITATION 
To keep a well free from dangerous bacteria, it 
should first of all be located on high ground and away 
from all pigpens, stables, or other outbuildings. Under 
no circumstances should any puddles of water be al- 
lowed near it. Around the mouth of the well a 
tough clay should be spread and packed in thoroughly. 
cement 
FIG. 6i. A shows a well so arranged that surface water and germs are kept 
out of it. B shows how surface water and germs get into a well. 
to form a water-tight layer over the soil. This should 
slope so as to carry all water away from the well. The 
whole task is to keep surface water out, and this can 
be done still better by cementing the upper part of 
the wall and laying a circle of cement over the surface 
of the soil, as is shown in Figure 61. The platform 
should be wide enough to keep any surface water what- 
ever from running down in behind the wall and getting 
into the well. 
The above precautions will do much to keep out of a 
well not only bacteria that are in the soil, but matter on DISEASE GERMS IN' WATER 
91 
which bacteria can feed and multiply. Yet if the earth 
about a well is polluted (as it is in thickly settled regions 
where there are many dry closets), some germs are cer- 
tain to find their way into the water. For this reason it 
has often been necessary in towns and cities to fill up 
Figs. 62 and 63. From which well would it be safe to drink the water ? 
wells, and where there is reason to think that a well 
has been the cause of disease, the use of water from it 
should certainly be stopped. 
Keeping germ carriers away from wells. No person 
who is sick, or who is caring for a case of infectious 
disease, should work with well buckets or about a pump. 
Neither is it safe to use water from a well where many 
people handle the rope and buckets, for we are finding 
that germ carriers among healthy people are so common 
that there is always danger that one of them may have 
been about the well. Any person who walks over 
ground that has been polluted with human wastes (as 92 
PRIMER OF SANITATION 
many dooryards are) and then stands on a well platform, 
may leave disease germs where they will get into the 
water. For this reason, a well should always have a 
clean, sound platform, built of two layers of boards to 
make it as nearly water-tight as possible, and the pump 
should be so arranged that water will not run back into 
the well around it. A well that is covered by a small 
house and from which water is pumped by a windmill is 
much easier to make safe than one in the open, from 
which the water is taken by a hand pump or drawn out 
by buckets. 
Freeing water from disease germs. It is the duty of 
every city either to secure pure water for its inhabitants, 
or, by filtering or in some other way, to remove danger- 
ous germs from the water that it sends to the homes of 
its people. Many cities fail to do this, however, and 
when one is compelled to use impure city water or water 
from an ordinary well or spring, the best plan is to boil 
it. Simply bringing it to the boiling point will kill all 
dangerous germs (page 158). Most house filters are 
almost useless, and some of them are worse than use- 
less, for they catch and hold matter in which bacteria 
breed and multiply, and the bacteria pass through the 
pores in most of them. Very fine porcelain filters, if 
they are carefully cleaned and attended to, do strain out 
bacteria, but they work very slowly, it is a great deal of 
work to care for them, and it is easier to boil water than 
to look after one of them. Filtering through animal 
charcoal takes certain coloring matter out of the water 
and makes it look clear and bright, but it does not re- 
move germs. It is always to be remembered that to use 
fruits, vegetable dishes, or milk vessels that have been DISEASE GERMS IN WATER 
93 
washed in impure water may be as dangerous as to drink 
the water. Bringing water to the boil will make it safe 
for drinking purposes. 
The danger of bathing in polluted water. When a 
person bathes in polluted 
water he of course gets 
whatever germs are in 
the water on his hands 
and face and probably 
also in his mouth. For 
this reason it is not well 
to swim in polluted wa- 
ter, and swimming pools 
are a real danger when 
constant attention is not 
given to their cleanliness 
andthedisinfectionof the 
water. The water in a 
swimming pool is usually 
disinfected with chlorin 
or a compound of lime 
that contains chlorin. 
Clear water not nec- 
essarily safe. Because 
the water in a well is 
clear or because people 
have been drinking it 
for a hundred years does 
not mean that it is safe. 
Germs are so small that they cannot be seen by the un- 
aided eye, and it is possible for a well to have been in 
good condition twenty-five years ago and to be receiving 
Fig. 64. Water like this is free from dis- 
ease germs unless it has been polluted by 
wastes from the bodies of the sick. 94 
PRIMER OF SANITATION- 
surface water now. It is possible, too, that many of the 
people who have drunk water from the well during the 
hundred years have died of diseases that they contracted 
from the water. Do not make the mistake of thinking 
that a well can be made safe by cleaning it out occa- 
sionally. Typhoid germs live longer in clean water than 
in dirty water, and a well can be made safe only by keep- 
ing disease germs out of it. 
POINTS TO BE REMEMBERED 
1. Nothing is more important in preventing germ diseases 
than pure drinking water. 
2. Intestinal diseases in particular are spread through water. 
3. The disease germs in water come from the human body. 
4. They get into the water from germ-laden wastes, from 
the hands of germ carriers, and in other ways. 
5. Great epidemics of typhoid fever and cholera have been 
caused by polluted water. 
6. Water from the surface of the ground (water from streams, 
springs, and shallow wells) is unsafe for drinking. 
7. Artesian water is usually safe, as is rain water that has been 
kept free from pollution. 
8. To keep wells free from germs, surface water and dirt from 
the platform must be kept out of them, and persons who 
are carrying germs should be kept away from them. 
9. It is dangerous to bathe in waters polluted with sewage or 
in swimming pools that are not kept disinfected. 
10. Clear water is not necessarily safe. CHAPTER TWENTY-ONE 
OTHER BACTERIAL DISEASES 
Besides the diseases we have already studied, there are 
many other diseases of man that are caused by bacteria. 
Most of these are tropical diseases, and we shall not even 
mention them here. In a considerable number of other 
diseases the particular germ that is responsible has not 
been surely determined, and we cannot tell whether these 
diseases are due to bacteria or to protozoa. There is also 
a great number of bacterial diseases of animals, and a 
considerable number of bacterial and fungous diseases 
of plants, for animals are seldom sick, and plants are 
almost never sick, unless they are attacked by germs. 
In this chapter we shall take up a few very different 
diseases that it is well to understand. 
MENINGITIS 
Every year there are in the United States over 
10,000 deaths from meningitis. The disease is caused 
by germs growing in the membranes around the brain 
and spinal cord. About two thirds of all cases of this 
disease are caused by pus-forming bacteria, the pneu- 
monia germ, the influenza germ, the tuberculosis germ, 
or the typhoid germ. The other cases of meningitis are 
caused by a special germ (Meningococcus)* that is not 
found in other diseases. When meningitis is caused by 
this germ, it is an infectious disease, often runs in epi- 
demics, and is sometimes called epidemic cerebro-spinal 
meningitis. Its attack is sudden and severe, and until 
very recently most cases ended in death. 
How the germ of epidemic meningitis enters the body. 
The germ of epidemic meningitis is abundant in the dis- 
1 Pronounced men-in'-go-kok'-kus. 
95 96 
PRIMER OF SANITATION 
charges from the nose of a patient who is suffering with 
the disease. It dies quickly from drying, and does not 
grow naturally in animals or outside the 
human body. It is spread in ways that 
do not require it to be long outside the 
body, as by handkerchiefs, drinking cups, 
the hands, or by droplets that have been 
coughed or sneezed out into the air. It 
is sometimes found in the noses of persons 
who have been about meningitis patients, 
and it is believed that it reaches the brain 
by working upward through the roof of the 
nasal chambers. Any one who is carrying 
this germ should be quarantined, and the 
sputum and discharges from the nose of a meningitis 
patient should be carefully destroyed. 
Curing meningitis. Recently a serum prepared from 
the blood of the horse has been used in the treatment 
of epidemic meningitis.1 This serum contains both an 
antitoxin and a substance that kills the meningitis 
germs. It is proving of great value, for of 1294 patients 
that were treated with it only about 31 per cent died, 
while of cases that are not treated with the serum, about 
70 to 75 per cent end fatally. Like the antitoxins for 
diphtheria and tetanus, meningitis serum should be used 
as early in the case as possible. 
Fig. 65. The 
germ of epi- 
demic cerebro- 
spinal menin- 
gitis. 
Different germs—the diphtheria, the pneumonia, or 
the pus-forming bacteria—may cause sore eyes, but 
SORE EYES 
1 This serum is of no value in cases of the disease caused by germs 
other than the meningococcus. OTHER BACTERIAL DISEASES 
97 
there is a particular bacterium (Koch-Weeks bacillus) 
that causes the epidemic form of sore eyes often called 
“pink eye.” This germ dies quickly from drying, and 
is not found to any extent in dust, but 
it is easily transferred on handkerchiefs, 
towels, wash basins, on the hands, and by 
flies, and children with this disease should 
not attend school. The infected eye 
should be carefully covered to keep germs 
from getting into the other eye. It is 
never safe to wash the eyes in a public 
wash basin or to wipe them on a public 
towel (page 197). Any infection of the 
eyes should be promptly treated by a physician, for 
continued inflammation may injure the blood vessels and 
linings of the eyelids. 
Fig. 66. The 
b a c i 1 lus that 
causes “pink 
eye." 
RHEUMATISM 
Acute rheumatism is caused by bacteria that settle in 
the joints and cause inflammation there. The germ has 
been thought by some to be a variety of streptococcus. 
Others think that while it is very similar to strepto- 
coccus, yet it is a different germ. When it attacks the 
valves of the heart, it may cause death. 
LEPROSY 
Leprosy is caused by an exceedingly slow-growing 
bacillus that is similar in many ways to the bacillus of 
tuberculosis. The germ probably gets into the body by 
being inhaled, or through wounds, or possibly by the bite 
of the mosquito. It is believed that several lepers have 
been cured by the use of a new remedy. 98 
PRIMER OF SANITATION 
BUBONIC PLAGUE 
Bubonic plague is the disease, that in the Middle Ages 
was called the Black Death. The germ attacks rats as 
well as men, and men usually get the disease from the 
bites of fleas that have been living on plague-stricken rats. 
Recently there has been a widespread epidemic of plague 
in the world, the disease being in all the continents and 
in one year in fifty-two different countries. It is most 
severe in India, where in 1907 it caused nearly a 
deaths. In the United States, plague succeeded in land- 
ing in San Francisco, Seattle, and New Orleans. In the 
cities it was soon exterminated among the rats, but in 
California it spread to the ground squirrels and is still 
being fought among them. The disease spreads from 
one country to another by infected rats traveling by ship, 
and many of our seaports are now rat-proofing the 
wharves along their water fronts in order to guard against 
the introduction of this dreaded disease (page 205). 
CHOLERA 
The cholera germ grows in the intestines and produces 
a toxin so powerful that death sometimes comes in a few 
hours. The germs are spread in the same ways that 
typhoid germs are spread. At the present time cholera 
is feared only in those countries where the germ theory 
of disease is not understood. In all countries where 
people understand the germ theory of disease, cholera 
has now disappeared. 
MUMPS 
It is believed that the cause of mumps is a small coccus 
that grows in the salivary glands. The incubation period 
is from thirteen to twenty-one days, and the patient is OTHER BACTERIAL DISEASES 
99 
dangerous to others for a week after the swelling of the 
glands is gone. 
BACTERIAL DISEASES OF PLANTS AND ANIMALS 
Bacterial diseases of animals. Among bacterial dis- 
eases of animals are the following : Swine plague among 
hogs; roup, white diarrhea, and cholera among fowls; 
milk-sickness and black-leg among cattle; distemper 
and glanders among horses; Malta, or Mediterranean, 
fever, among goats and cattle ; and many other diseases 
of animals that cannot be mentioned here. The glan- 
ders bacillus may attack man (sometimes causing a fatal 
illness), and milk-sickness and Malta fever may be con- 
tracted by man from milk. 
Bacterial diseases of plants. Pear blight; a disease 
much dreaded by orchardists, called crown-gall; the 
wilt disease of young cucumbers, melons, squashes, and 
pumpkins; the brown rot of the 
potato, tomato, and eggplant; the 
black rot of cabbages, rutabagas, and 
turnips; a disease of sweet corn; a 
knot disease of the olive; a rot of 
the calla lily; and a widespread stem 
rot of the potato — all these are plant 
diseases that are caused by bacteria. 
It is thought that bees carry pear- 
blight germs from tree to tree during 
blossoming time, and that they are 
entirely responsible for the spread 
of the disease. The germs of wilt 
diseases are probably spread by beetles and squash bugs 
that feed on the diseased plants. 
FlG. 67. A muskmelon 
plant that has been at- 
tacked by wilt bacteria. 100 
PRIMER OF SANITATION 
Diseases caused by fungi. Many diseases of plants — 
rusts, smuts, mildews, many of the rots, and various 
other diseases — are caused by small plants (fungi) that 
are similar to molds. These fungi are much larger than 
bacteria, their bodies being composed of long, thread-like 
filaments. A few fungi enter the hair follicles and grow 
in the human skin. Among the diseases caused by them 
are ringworm, tetter, barber’s itch, and a kind of itch 
that attacks any part of the body. These diseases 
are infectious, and care is necessary to prevent their 
spread. Thrush, a white growth found in the mouths 
of young babies, also is caused by a fungus. 
POINTS TO BE REMEMBERED 
1. Meningitis may be caused by any one of several germs, but 
the epidemic form of the disease has a special germ of its 
own. 
2. In epidemic cerebro-spinal meningitis, the germ is in the 
discharges from the nose of the patient and enters the body 
through the nose. 
3. A new serum is proving very valuable in treating this 
disease. 
4. Great care should be taken to guard the eyes when sore 
eyes are epidemic, and all cases of infectious sore eyes 
should be quarantined. 
5. Acute rheumatism, leprosy, plague, and cholera are bacteria] 
diseases. 
6. Bacteria cause many diseases of animals and plants. 
7. Many plant diseases and some skin diseases in man are 
caused by fungi that are larger than bacteria. CHAPTER TWENTY-TWO 
PROTOZOA 
The bacteria are the smallest of all plants. The 
protozoa are the smallest of all animals. The smallest 
protozoa look like tiny specks under the most powerful 
microscope, and are no larger than very small bacteria. 
The largest of them are much larger than any bacteria, 
but they can barely be seen with the naked eye. 
Protozoa are abundant in both fresh and salt water. 
Many of those that live in the ocean have shells, and so 
Fig. 68. Phosphorescence in the water is caused by multitudes of protozoa. 
abundant are they that great beds of chalk and lime- 
stone are built by them. Others are phosphorescent 
(give off light), and in the warmer seas the waves at 
night are often fringed with light from the multitudes 
of protozoa in the water. 
Many kinds of protozoa live in the bodies of animals, 
and almost every animal, from worms and insects up 
to man, suffers from diseases that are caused by them. 
101 102 
PRIMER OF SANITATION 
Among the protozoan diseases of man are several that 
are carried by insects, and these diseases are worse in 
Fig. 69. Shells of protozoa in a piece of chalk as seen under a microscope 
the warmer parts of the earth, where insects are most 
abundant. 
In the following chapters we shall consider protozoan 
diseases and, along with them, several diseases due to 
very small germs that may or may not belong in the 
protozoan class (page 194). 
POINTS TO BE REMEMBERED 
1. Protozoa are very small animals. 
2. Protozoa are abundant in both fresh and salt water. 
3. They cause many diseases of animals and men. 
4. Several protozoan diseases are spread by insects. CHAPTER TWENTY-THREE 
MALARIAL FEVER AND YELLOW FEVER 
Malarial fever does not cause so many deaths as 
some other diseases, but because it is found over a great 
part of the world, and because in malarial countries a 
great number of people are affected by it for long periods 
of time, malaria must be counted as one of the most im- 
portant of the diseases that afflict mankind.1 No com- 
munity can prosper as it should while its people have 
malaria, for a person who is suffering from this disease 
cannot have the energy and ambition that he should 
have to carry on his work. 
The germ of malaria. Mala- 
ria is caused by small protozoa 
that live in the red blood cor- 
puscles. A malaria germ 
grows and becomes larger in 
a corpuscle and then divides 
into a number of parts, each of 
which is a young germ. The 
corpuscles then break into 
pieces, leaving the young 
germs free in the blood. Each young germ now enters 
a fresh red corpuscle, grows in it, and divides into a 
number of germs. These young germs then break 
forth and attack other corpuscles. 
The cause of the chill in malaria. While they are 
growing in the corpuscles, the malaria germs produce 
Fig. 70. The growth of the mala- 
ria germ in a red blood corpuscle. 
1 In malarial regions 50 per cent of the people may have the germ of 
malaria in the blood. Almost one half of these do not have chills and 
fever, but they are suffering from a slow, chronic form of the disease that 
robs them of their strength. It has been calculated that in a severe case of 
malaria there may be a pint of the germs in the blood. 
103 104 
PRIMER OF SANITATION 
toxin. When the corpuscles break down at the time 
the germs come out into the blood, a large amount of 
toxin is set free in the blood at one time. This toxin 
poisons the cells of the body and brings on the chill and 
fever. There are several different kinds of malaria 
germs, and the chill comes every day, every other day, 
or every third day, according to the length of time it 
takes for the germs to become full-grown and break out 
of the corpuscle. In their growth the malaria germs 
destroy great numbers of red blood corpuscles, and the 
loss of these millions of corpuscles, as well as the poison- 
ing of the cells by the toxin, injures the body. 
How the malaria germ gets into the body. The mala- 
ria germ grows in a certain kind of mosquito (page 112) 
as well as in man, and it gets into our 
bodies from the bites of these mosqui- 
toes. When the mosquito feeds on man, 
it thrusts its proboscis (bill) down through 
the skin and sucks out the blood. When 
a mosquito draws blood from a person 
who has malaria, it takes malaria germs 
into its stomach with the blood. These 
germs pass into the walls of the mosquito’s 
stomach and multiply in little sacs on 
the outside of the stomach walls. The 
sacs then burst, and great numbers of 
the germs pass through the mosquito’s 
body to the salivary glands. The germs appear in the 
saliva in about ten days from the time when they were 
first taben into the stomach. 
Now the opening in the proboscis of the mosquito 
is too small to allow the blood corpuscles to pass up 
Fig. 71. The stom- 
ach of a mosquito 
that is infected with 
malaria. The ma- 
laria germs grow in 
the sacs on the 
mosquito’s stomach. MALARIAL FEVER AND YELLOW FEVER 
105 
through it, and when the mosquito bites it injects saliva 
into the wound.1 The saliva breaks up and dissolves 
the corpuscles, and the mosquito is then able to draw 
out the blood. If the malarial germs are in the salivary 
Fig. 72. Diagram of a mosquito’s body. The malaria germs pass from the 
stomach to the salivary glands. Then they are injected through the proboscis 
into the persons whom the mosquito bites. 
glands of the mosquito, they will, of course, be injected 
into the wound with the saliva. Unless the body is able 
to destroy them, the germs then enter the red corpuscles, 
and in about a week from the time the man was bitten 
the disease appears. 
Malaria spread only by mosquitoes. It is a common 
idea that malaria is caused by drinking impure water or 
by “ miasmas,” or poisonous vapors, from swamps or 
damp ground. This idea is not correct. In Italy many 
1 It is the poisonous saliva of the mosquito that causes the itching and 
spelling that follow a mosquito bite. 106 
PRIMER OF SANITATION 
experiments have been made, during which persons 
drank water from the worst malarial marshes in Italy 
and Sicily, and inhaled the air of the marshes. Not a 
single case of malaria ever followed these experiments. 
Near Rome, in a hut that stood in the very midst of the 
Pontine marshes (one of 
the worst malaria-stricken 
regions in the world) two 
English scientists lived 
for several months dur- 
ing the worst of the 
malaria season. They 
breathed the air that came 
from the damp lowland 
on which the house stood, 
and drank the water of the 
region that was supposed 
to cause malaria. In every 
way they lived as the people about them lived, except 
that in the evenings they retired to their carefully 
screened hut before the mosquitoes came out, and 
stayed behind their screens until the sun was up and 
the mosquitoes had retired. These men had no symp- 
toms whatever of malaria, although the people all about 
them were suffering from the disease. 
At the same time mosquitoes were caught in Italy, 
and, after they had been allowed to bite a malaria pa- 
tient, were sent to London. There a physician who 
lived in England and who had never had malaria allowed 
them to bite him. In a short time he developed a case 
of Italian malaria and the germs were found to be abun- 
dant in his blood. These and a large number of other 
Fig. 73. By screening themselves from 
mosquitoes, two Englishmen lived for 
several months in one of the worst ma- 
larial regions in all Italy, without symp- 
toms of the disease. MALARIAL FEVER AND YELLOW FEVER 
107 
similar experiments leave no room to doubt that it is by 
the bite of the mosquito and not by water or by damp 
air that the malaria germ 
enters the body. 
Killing malaria germs. 
There is no medicine 
known that will kill the 
germs of most diseases 
after they get into the 
body, without at the same 
time killing our own cells. 
Fortunately for us, the 
human body usually can 
endure an amount of qui- 
nine that will kill the germs of malaria. There is there- 
fore, in a cure for malaria. 
Preventing malaria. It is better to prevent any disease 
than to try to cure it, and it is better to prevent malaria 
than to try to kill the germs after they get into the 
body. The following are the best ways of preventing 
the spread of malaria : — 
Screening malarial patients from mosquitoes. Mos- 
quitoes that have not bitten persons who have malaria 
are free from the germs, and cannot spread the disease. 
But it has been found that in a house where there is a 
malaria patient the mosquitoes are usually infected and 
are able to give the disease to others. In regions where 
there is only an occasional case of malaria, or where 
only a few persons are living close together (as in a 
country farmhouse), much can be done to check the 
spread of malaria by keeping patients under mosquito nets 
until the germs disappear from the blood (page 203). 
.From. Italy 
Fig. 74. Germs of malaria were sent 
from Italy to England in a mosquito, 
and a physician who was bitten by the 
mosquito developed malaria. 108 
PRIMER OF SANITATION 
Avoiding unnecessary exposure to mosquitoes. Persons 
living in malarial regions should keep their houses care- 
fully screened, and should sleep under mosquito nets 
during the mosquito season. They should visit houses 
that contain infected mosquitoes only in the middle of 
the day. They should remain indoors in the morning 
and evening, when mosquitoes are active, and on cloudy 
days they should keep away from woods and swamps 
where mosquitoes are flying. Care should always be 
taken in selecting places for camping and fishing trips, 
for one night spent among mosquitoes may start an 
attack of malaria that will last for months. 
Destroying mosquitoes. In towns and around country 
houses that are at all favorably located, mosquitoes may 
be destroyed by removing their breeding places. So 
well do we understand how to do this that there is now 
little reason why one who does not live in a swampy 
region should have malaria. The best ways of destroy- 
ing mosquitoes will be discussed in the next chapter. 
The use of quinine. In some rural regions it is impos- 
sible to destroy all the mosquitoes, and a more hopeful 
method of attacking the malaria problem seems to be by 
the examination of the blood of all the people and treat- 
ing with quinine those in whose blood the germs are 
found. Recent experiments indicate that it is possible by 
long and thorough quinine treatment of malaria patients 
to free all the people of a region from the germs of the 
disease. In this way not only those who are afflicted 
with malaria are cured, but it is made impossible for the 
mosquitoes to become infected and the disease dies out. 
Small doses of quinine should be taken daily as a preven- 
tive of malaria by those who are exposed to the disease. MALARIAL FEVER AND YELLOW FEVER 
109 
YELLOW FEVER 
The germ of yellow fever 
has not been discovered 
(page 194). It is known, 
however, that the disease is 
spread only by a mosquito of 
a certain kind (Fig. 81). By 
screening yellow fever patients, 
by quarantining, by killing in- 
fected mosquitoes in houses 
where the disease has ap- 
peared, and by removing the 
breeding places of mosquitoes, 
the disease can be controlled. 
In our own country it will 
never again # be allowed to 
spread. 
Fig. 75. Dr. Walter Reed. On 
the tablet marking his grave is 
the inscription : “ He gave to 
man control over that dreadful 
scourge, yellow fever.” 
POINTS TO BE REMEMBERED 
1. Because of the great number of persons who are attacked 
by it, malaria is a very important disease. 
2. The malaria germs grow in the red blood corpuscles. 
3. They break forth from the corpuscles at the time of the 
chill. 
4. The malaria germ is carried only by one kind of mosquito. 
5. The malaria germ is one of the very few germs that may be 
killed with medicine after it gets into the body. 
6. Malaria may be prevented by screening malaria patients, 
by avoiding exposure to mosquitoes, by destroying mos- 
quitoes, and by the use of quinine. 
7. Yellow fever is contracted only from the bite of a mosquito. CHAPTER TWENTY-FOUR 
MOSQUITOES 
The mosquito, more than any other one agency, has 
driven man from the warmer and more fertile portions 
of the earth to the colder and more barren regions. It 
carries not only the germs of malaria and yellow fever, 
but also the germs of dengue, or “break-bone” fever, 
and a small worm (Filaria) that lives in the blood and 
causes an enormous swelling (elephantiasis) of the limbs 
or other parts of the body. The two latter diseases are 
common in the tropics and both are found to a certain 
extent in some of our southern 
states. The germs of several 
diseases of man not found in 
our country, and of certain dis- 
eases of birds, also are carried 
by mosquitoes. Where it is 
possible to do so, the best way 
to end all these diseases is to destroy the mosquitoes. 
To work at this intelligently it is necessary first to 
know the life history and the habits of the mosquito. 
Life history of the mosquito. The mosquito lays its 
eggs on water. In about a day the egg hatches into a 
larva (commonly called a wiggler or wiggle-tail) that 
swims about actively in the water. The larva takes in 
air through a breathing tube, which it thrusts out through 
the surface of the water to the air, as shown in Figure 77. 
In from seven to fourteen days the larva changes its 
form. The head and the fore part of the body become 
much heavier, and the breathing tubes shift to the back 
of the body. In this stage it is called a pupa (commonly 
called a tumbler, because, instead of wriggling as it 
Fig. 76. A is a raft of mosquito 
eggs; B is a single egg. 
110 MOSQUITOES 
111 
swims, it tumbles over and over). In from two to 
five days — ten to twenty days from the time the 
egg was laid — the pupa splits down the back, and 
the adult mosquito comes out and flies away. 
In the larva and pupa stages, mosquitoes feed on 
small plants and animals that are in the water. In the 
adult form, they live chiefly by sucking the juices from 
plants, but they eagerly attack animals and suck the 
blood from them when there is an opportunity to do so. 
How long a mosquito naturally lives in the adult form is 
Fig. 77. A is a mosquito larva; B is a pupa; C is an adult mosquito 
coming out of an old pupa. 
not known, but one has been kept for seventy-six days, 
and considerable numbers of them live through the 
winter, hidden away in crevices and cracks. The young 
and the eggs of the mosquito are not killed by being 
frozen, and mosquitoes often come out in the spring from 
eggs or larvae that have lived through the winter. 
Anopheles. The kind of mosquito that carries the 
germ of malaria is called Anopheles (a-nof'-e-lez). It is 112 
PRIMER OF SANITATION 
an almost silent mosquito, that does most of its biting 
in the early part of the night and early in the morning. 
It can readily be distinguished from other mosquitoes 
by the black spots on its wings, and by its habit of 
elevating the back part of the body, or standing up on 
its head, when resting and biting. Other mosquitoes 
Fig. 78. A is the Anopheles mosquito (the mosquito that carries malaria), 
showing its position while resting, and the spots on its wings. B shows the 
common mosquito (Culex). 
are often carried considerable distances by the wind,1 
but the Anopheles has a habit of clinging to weeds, 
shrubs, and bushes when the wind blows, and is not 
often found far (seldom more than a few hundred yards) 
from the place where it is hatched. The mosquitoes 
•that give people malaria are usually2 raised by those 
same people, or by their neighbors. 
1 There are some mosquitoes that breed in salt marshes and travel for 
miles. These rarely enter houses, and they do not carry malaria. 
2 The yellow fever mosquito is a domestic mosquito and breeds almost 
entirely in water about houses. The Anopheles, on the other hand, is a 
half-wild mosquito, and likes best to breed in the fields and woods, in 
ponds, small streams, and ditches. MOSQUITOES 
113 
Destroying the breeding places of mosquitoes. The 
first thing in the fight with mosquitoes is to deprive them 
of breeding places near human dwellings. An old fruit 
can may catch and hold 
enough rain water to 
breed a large number of 
mosquitoes; in the course 
of a summer, an almost 
unlimited number1 can 
come from a water barrel 
or an open cistern; and 
an undrained ditch by 
the roadside may supply 
enough mosquitoes to tor- 
ment and infect with 
malaria all the people in 
the vicinity. 
Old cans and pans should be cleared away; water 
barrels, tanks, and cisterns should be screened so that 
the mosquitoes cannot get to them to lay their eggs; 
sagging eave troughs should be braced up so that no 
water will stand in them, for in an eave trough the 
larvae may start in a very small quantity of water and then 
be washed down into the cistern, where they will com- 
plete their development. All pools and puddles about 
houses should be drained; and wells must be watched 
and if necessary covered, for sometimes the larvae are 
found in wells. Weeds and shrubbery in which the mos- 
quitoes can find a dark, cool place to hide during the hot 
part of the day, or when the wind blows, should be cut 
FiG. 79. The gutter over this doorway 
became stopped up with leaves, and in 
the water that stood there, hundreds oi 
mosquitoes were hatching. {Afterphoto- 
graph by the Richmond Board of Health^ 
1 Nineteen thousand eggs and yaung mosquitoes have been found in a 
rain barrel at one time. 114 
PRIMER OF SANITATION 
down. As long as mosquitoes are found about the house, 
the work should be continued, for if all breeding places 
near houses are removed, Anopheles mosquitoes and 
generally all other mosquitoes will disappear. The work 
of destroying mosquitoes in cities and towns must be 
taken up by public officials who have authority to compel 
every one to remove the breeding places on his premises. 
Killing mosquito larvae with kerosene. When pools 
of water cannot be drained, it is an easy matter to kill all 
Fig. 8o. This house was so infested with mosquitoes that the owner was about 
to sell it at a sacrifice, when he learned from a health official that a half-hour 
spent in draining the ditch or in sprinkling it with kerosene would free his 
family from annoyance and the danger of disease. 
young mosquitoes in them by pouring a little kerosene 
on the water. This forms a film over the water, shutting 
the larvas off from the air, and killing them in a few 
minutes. If the kerosene is washed away by rains, it 
must be renewed within ten days, for this is about the 
time it takes a mosquito egg to grow into a mosquito. 
Minnows, goldfish, and other small fish feed on the MOSQUITOES 
115 
mosquito larvae, so by introducing these into a pond, 
the number of mosquitoes that breed there may be 
greatly lessened. 
Killing adult mosquitoes. After mosquitoes have been 
allowed to hatch and scatter themselves, it is hard to 
get rid of them, but when mos- 
quitoes in a house are known 
to be infected with yellow fever 
or malaria, it is very important 
to kill them at once. This is 
usually done by burning sulfur 
in the rooms that contain the 
mosquitoes.1 In fighting dis- 
eases that are spread by mos- 
quitoes, the importance of 
screening sick persons who 
may infect the mosquitoes with 
germs must not be forgotten. 
Where mosquitoes are plenti- 
ful, often the only way by 
which an individual can pro- 
tect himself is to screen his house and bed and stay 
indoors when the mosquitoes are abroad. 
Communities that have successfully fought mosquitoes. 
It is a very easy matter, and not at all expensive, to 
banish mosquitoes almost completely from a town near 
which there are no extensive natural breeding places. 
Fig. 8i. The yellow fever mos- 
quito (Stegomyia). This mos- 
quito has light bands around the 
body and on the legs. It breeds 
near houses and does not fly far 
from where it is hatched. 
1 The fumes of burning sulfur kill flies, fleas, and bedbugs, as well as 
mosquitoes, but they destroy the color in carpets and other cloth articles, 
and blacken the gilt on picture frames, book covers, and furniture. Burn- 
ing insect powder (pyrethrum) will stupefy flies and mosquitoes so that 
they can be swept up and burned. 116 
PRIMER OF SANITATION 
Even in regions where there are large marshes and 
many streams and ponds, by systematic work commu- 
nities can free themselves from mosquitoes. This has 
been done in Panama, Cuba, Brazil, and elsewhere 
in the tropics, and the inhabitants of the North Shore 
of Long Island and of certain towns in New Jersey, 
where the mosquitoes were formerly so abundant that 
they were a veritable pest, have now conquered their 
winged enemies. In this book there is not space to tell 
of the work that has been done in these places, but from 
the Department of Agriculture at Washington, D.C., 
and from state and city boards of health, bulletins can 
be obtained that give many interesting facts about mos- 
quitoes, with directions for fighting them. 
POINTS TO BE REMEMBERED 
1. Mosquitoes carry malaria and yellow fever. 
2. In ten days the mosquito can pass through the larva and 
pupa stages and come out in the adult form. 
3. The mosquito that carries malaria has spotted wings, and 
when resting stands upon its head. 
4. The mosquitoes that carry malaria and yellow fever spend 
their lives near where they hatch. 
5. A town or a country house can be freed of mosquitoes by 
removing the breeding places. 
6. Public health officials are absolutely necessary in fighting 
mosquitoes. 
7. Mosquito larvae may easily be killed with kerosene. 
8. When the mosquitoes in a house are infected with disease 
germs, they may be killed by burning sulfur in the house. 
9. Many towns and communities, some of them very unfavor- 
ably located, have freed themselves from mosquitoes. CHAPTER TWENTY-FIVE 
SMALLPOX 
Up to about a hundred years ago, smallpox was one 
of the most terrible diseases known to man. It is esti- 
mated that in the eighteenth century it killed 60,000,000 
people, and that 6,000,000 of the 12,000,000 inhabitants 
of Mexico died from it when it was introduced into that 
country by the Spaniards. In Europe nearly every one 
sooner or later had to undergo an attack of the disease. 
“ It was always present, filling the churchyards with 
corpses, tormenting with constant fears all it had not yet 
stricken, leaving on those whose lives it spared the 
hideous traces of its power, turning the babe into a 
changeling at which the mother shuddered, and making 
the eyes and cheeks of the betrothed maiden objects of 
horror to the lover.” Fortunately for us, a method of 
preventing smallpox has been discovered, and in civilized 
countries it has now become a rare disease. 
The germ of smallpox. Smallpox is caused by a 
small germ that lives in the skin and in the lining of 
the mouth, throat, and nose, and sometimes in the 
trachea and esophagus (page 194). The* germs cause 
pustules or sores to form in the deeper layers of the 
skin. These break through to the surface of the skin, 
and in the later stages of the disease the matter from 
these pustules dries as scabs over the body. The incuba- 
tion period of smallpox is from seven to twenty-one days. 
Some races of smallpox germs are weak and produce a 
type of the disease so mild that it is often mistaken for 
chicken pox. Other races are very virulent and cause 
smallpox of so malignant a type that numbers of the 
victims die, and many of those who recover lose their 
117 118 
PRIMER OF SANITATION 
sight. In this disease, as in diphtheria and other in- 
fectious diseases, it would seem that weak races of 
germs may become 
strong, and that a 
mild type of the dis- 
ease may at any time 
change to the malig- 
nant form. It is 
important, therefore, 
that mild cases of 
smallpox should be 
quarantined and not 
pronounced chicken 
pox; for from a mild 
case of the disease, 
germs may be spread 
abroad that will be- 
come virulent and bring many persons to their graves. 
How smallpox germs are spread. The germs of small- 
pox are abundant in the matter on the skin of a small- 
pox patient, they are in the discharges from the mouth 
and nose, and are found in great numbers in the scales 
that come from the skin during recovery from the 
disease. These germs may be scattered about by the 
patient’s coughing or sneezing, they are left on anything 
he touches, they may be carried on the feet of flies, and 
it is possible that they are at times blown for short dis- 
tances through the air in the light, dry scales that come 
from the skin. Smallpox germs may be dried for 
months without being killed, and on clothing, books, 
letters, old rags, and many other things, they are some- 
times carried about. 
Fig. 82. By vaccination, smallpox, the dis- 
ease formerly most dreaded in armies, is now 
entirely prevented among soldiers. SMALLPOX 
119 
VACCINATION 
To very few human beings has nature given white 
corpuscles and germicidal substances that can resist the 
smallpox germ. Up to the time vaccination began to 
be practised, more than 95 per cent of all persons suf- 
fered from it, and people con- 
sidered it a disease that every 
one must have, just as we 
look on chicken pox and 
mumps as diseases that most 
of us will probably have to 
go through with sooner or 
later. About the year 1800 
vaccination began to be prac- 
tised, and smallpox at once 
began to decline. Now vac- 
cination is more or less com- 
pulsory in every civilized 
country in the world. Where 
it is thoroughly carried out, 
smallpox has almost ceased 
to exist, but where the people 
are not vaccinated, or a considerable number of them 
are not vaccinated, it is still impossible to prevent the 
spread of the disease. This is because mild cases escape 
quarantine, because the germ withstands drying for a 
considerable period of time, and because it is so powerful 
a germ that if 100 unvaccinated persons are exposed to 
it, from 95 to 98 of them will be attacked by the disease. 
Vaccination an almost perfect protection against small- 
pox. In April, 1912, nine cases of smallpox were 
Fig. 83. Edward Jenner, who in 
1797 discovered vaccination, the 
greatest medical discovery the 
world has ever known. 120 
PRIMER OF SANITATION' 
reported in Niagara Falls, New York. There had been 
much opposition to vaccination among the people of 
this part of New York State, and little vaccination had 
been performed for twenty years. When the smallpox 
epidemic started, the local 
health officer was inactive, 
and the disease spread until in 
November, 1913, there were 
66 cases, and in January, 1914, 
there were 204 cases. Effec- 
tive measures were then taken 
for the control of the epi- 
demic, and by March 6 more 
than 25,000 persons had been 
vaccinated and the cases were 
put under strict quarantine. 
In February there were 121 
cases, in March 10, in April 2, 
in May 1, and in the next five 
months none. Of the 550 cases reported during the 
epidemic, only 8 had been vaccinated within five years. 
From time to time certain persons in England have 
opposed vaccination, and for a while the center of this 
opposition was in Gloucester. In 1895 that city had a 
population of 42,000, among whom were a very consid- 
erable number of persons who had not been vaccinated. 
In the last weeks of 1895 smallpox broke out, and 
a great epidemic of 1979 cases and 439 deaths oc- 
curred. An attempt was made to control the dis- 
ease by quarantining and careful disinfection, but this 
was an entire failure. In January, 1896, there were 
28 cases, in February 146 cases, in March 644 cases, 
Fig. 84. Dr. Benjamin Water- 
house, who introduced vaccination 
into America in 1800. He insisted 
on the use of pure virus and keeping 
the wound clean. SMALLPOX 
121 
and in April 744 cases. By the end of April more 
than 36,000 of the inhabitants had been vaccinated, and 
Gloucester was the best vaccinated city in the world. 
The epidemic at once began to decline, and by August 
it had disappeared. 
In Philadelphia there was a considerable epidemic 
of .smallpox during the years 1901-1904. During this 
period more than 3500 cases were admitted to the Munic- 
ipal Hospital, and of these 3500 cases not one had been 
successfully vaccinated within 
five years. During this time 
many physicians and nurses 
were employed in the hospi- 
tal, and more than 700 medi- 
cal students were taken to 
visit the patients. Not one of 
all these persons contracted 
smallpox except one student 
who was opposed to vaccina- 
tion and untruthfully said that 
he had been vaccinated. At 
one time it was necessary to 
enlarge the hospital, and fifty 
or sixty workmen were em- 
ployed to do this. All of 
them were vaccinated except 
two, and these two and no 
others took the disease. Again it was necessary to 
enlarge the hospital, and another squad of workmen 
was employed. For some reason two of these were 
not vaccinated. These two were attacked by small- 
pox, while again all the workmen who had been vacci- 
Fig. 85. Thomas Jefferson, one 
of the most broad-minded and far- 
seeing Americans of his time. In 
1806, writing to Edward Jenner, 
he said, “ Future nations will know 
by history only that the loathsome 
smallpox has existed and by you 
has been extirpated.” 122 
PRIMER OF SANITATION 
nated escaped. Thus within the hospital all of the 
hundreds of persons who had been vaccinated escaped 
the disease, and all five of those 
who had not been vaccinated con- 
tracted it. 
Many pages could be filled with 
similar statistics showing that vacci- 
nation almost surely prevents small- 
pox. Yet many persons seem never 
to have heard of these facts, for 
there are still in our country socie- 
ties that actively oppose vaccination. 
Some people think that among those 
who do not believe in vaccination 
are some of the prominent physi- 
cians of the country. This is a 
great error, for hardly any of the 
physicians who oppose vaccination 
are even graduates of medical col- 
leges, and none of them have any 
prominence in their profession. The 
leaders of medicine for the last hun- 
dred years have believed in vaccina- 
tion and have practised it, and today 
there is not a prominent medical 
man in America who is opposed to 
it. On this point the Medical Soci- 
ety of the State of Pennsylvania 
says: “ We know of no physician of 
eminence in this country who is not 
a believer in — nay, even an ardent 
advocate of—vaccination.” 
Fig. 86. Diagram showing 
how vaccination protects 
against smallpox. During 
1912,1913, and 1914, health 
officials in the United 
States secured the vacci- 
nation histories of 12,880 
smallpox patients. Of 
these, 11,236 (more than 
87 per cent) had never 
been successfully vacci- 
nated; 1104 (slightly more 
than 8 per cent) had been 
vaccinated more than 7 
years before the attack; 
and only 540 (a little over 
4 per cent) had been vac- 
cinated within the last 7 
years before the attack. 
(Data from United States 
Public Health Report of 
October 2, 1914.) SMALLPOX 
123 
How vaccination protects against smallpox. The germ 
of smallpox flourishes in man. It grows in cattle also, 
causing the disease called cowpox. After growing in the 
cow, this germ seems to be weakened and changed so 
that it grows feebly in man and has only a slight power 
of producing disease. 
In vaccination, germs from a cow are put into the 
human body. Here they grow and begin to produce 
the mild inflammation that follows vaccination. The 
body now works up the germicidal substance for these 
germs, and because the germs are weak, the body is 
able to kill them out before they can multiply to any 
extent. After this is done, the germicidal substance re- 
mains in the blood, and if smallpox germs at any time 
get into the body, the germicidal substance is there 
ready to kill them and keep the disease from getting a 
start. A person who has been successfully vaccinated 
is therefore in much the same condition as a person who 
has had a light attack of smallpox, for he has in his 
blood a substance that will kill any smallpox germs that 
may get into his body. 
How long vaccination protects against smallpox. After 
vaccination, the germicidal substance in the blood be- 
comes weaker and weaker, but seldom disappears 
entirely. Just when it becomes so weak that it is nec- 
essary to be vaccinated again, it is impossible to say. 
Sometimes it is fairly strong after seven, eight, nine, or 
ten years. In a very few persons it disappears so rap- 
idly that in nine months it fails to protect against small- 
pox. The safest way is to be vaccinated every few years, 
and when there is danger of being exposed to smallpox, 
to be vaccinated again if more than nine months have 124 
PRIMER OF SANITATION 
passed since the last vaccination. There can be no 
mistake in this, for if the germicidal substance is still 
strong in the blood, all the germs put in by vaccination 
will be killed and the vaccination will not take. If the 
vaccination does take, it is a sure sign that the germi- 
cidal power of the body is beginning to run low and that 
another vaccination is needed. 
Why every one should be vaccinated. Every one should 
be vaccinated to protect himself. We never know when 
the smallpox germ may come to us from the seats of a 
car, from a letter, from the clothes of some person, or in 
any one of many other ways. If smallpox germs do get 
to a person who has been successfully vaccinated, that 
person will in all probability kill the germs and suffer no 
harm. If he has not been vaccinated, he will probably 
suffer from an attack of smallpox, with a considerable risk 
of losing his life. Even if he recovers, he will be fortu- 
nate if he is not more or less scarred and pitted for life. 
Every one should be vaccinated to protect others. Per- 
sons who have smallpox cause expensive quarantine, 
they interfere with business and with schools, and by 
scattering abroad smallpox germs they endanger the 
lives of others. A person who refuses or neglects to be 
vaccinated and then takes smallpox, makes a public 
nuisance of himself, and it is neither fair nor right to be 
a nuisance to one’s friends and neighbors. In 1885 one 
man carried smallpox to Montreal and started an epi- 
demic that cost over three thousand lives. 
Little danger in vaccination. Vaccination causes only 
a small sore, and there is practically no danger from 
it when it is properly done. How little danger there 
really is from it is shown by the fact that 3,709,187 SMALLPOX 
125 
persons were vaccinated by government officials in the 
Philippine Islands, during the years 1907-1908, without a 
single death. The greatly swollen arms and running 
sores that sometimes follow vaccination are caused by 
pus-forming bacteria and are not a true part of vaccina- 
Fig. 87. In the Philippine Islands, before the American occupation, only a 
small part of the inhabitants were vaccinated. In 1897, about 40,000 people 
died from smallpox. In 1907, there were 304 deaths from this disease in all the 
islands. It is vaccination that has caused this decrease, for in most parts of 
the Philippines there is no quarantine or disinfection of a kind that would have 
any effect in controlling smallpox. 
tion at all. The pus-forming germs usually get into the 
wound in impure virus, from infected instruments (as from 
a lancet that has been used in opening a boil), from an 
unclean skin, or from dirt that gets into the wound. Only 
pure virus should be used,1 the skin and instruments 
should be clean, and the wound (like any other wound) 
should be protected from pus-forming and tetanus germs. 
1 Only virus that has been carefully prepared and sealed in glass tubes 
should be used. 126 
PRIMER OF SANITATION 
When one gets a great sore on the arm, it is not possi- 
ble to tell whether the vaccination virus is working or 
not, and many persons who think they have been sue 
cessfully vaccinated have only had a growth of pus- 
forming bacteria in their arms. 
A point about germ diseases that should be understood. 
It is a common idea that if the blood is “ pure ” we shall 
be protected from germ diseases, and if the blood is 
“ impure ” we shall suffer from these diseases. This 
idea is not correct. A person’s blood may be as pure 
as any flowing in the veins of man, and yet that person 
will fall a victim to smallpox germs if he lacks in his 
blood the substance that kills those germs. His muscles 
may be like bands of steel and his nerves may be tin- 
gling with the joy and vigor of perfect health, and yet 
if in his blood there is not the particular substance that 
kills the tubercle bacillus, he had best beware of that 
germ. He may even, as we have already pointed out 
(page 13), have substances in his blood that will enable 
him to kill some kinds of germs and yet may fall an 
easy victim to germs of another kind. Resistance to 
germs is, therefore, not a question of pure blood, but a 
question of having in the blood particular substances 
that will kill particular germs. 
In former chapters we have advised you to keep up 
the health of the body so that it will be able to kill 
germs, and it is true as a general statement that when 
the body is in health it is able to manufacture more of the 
substances that kill germs it can manufacture when 
it is weak. You should know, however, that for reasons 
that are not understood, the body sometimes suddenly 
loses its power to resist germs even when it seems to be SMALLPOX 
127 
in health. You should also understand that before small- 
pox germs nearly every one goes down as the wheat 
goes down before the sickle, and that the only way you 
can make yourself safe from this disease is to get your 
body, beforehand, to work up a supply of the germicidal 
substance for the smallpox germ. Therefore, when any 
one begins to tell you that health consists in keeping 
the blood pure, and that vaccination is contrary to 
the principles of health because it introduces into the 
body matter from a cow that will cause the blood 
to be impure — when any one talks to you after this 
fashion, pay no attention at all to him. For though 
your blood were as pure as the crystal water from a 
snow-capped mountain peak, it would not kill the small- 
pox germ unless it contained the germicidal substance 
for that germ. It is strong blood, and not pure blood, 
that we need in our battle with the germs. 
POINTS TO BE REMEMBERED 
1. Until vaccination was discovered, smallpox was the most 
dreaded of all diseases. 
2. The smallpox germ can withstand drying and is easily spread. 
3. Vaccination almost surely protects against smallpox. 
4. In vaccination a weak race of smallpox germs from cattle 
is put into the body. 
5. The body produces a substance to kill these germs. 
6. This germicidal substance then remains in the blood. 
7. Any danger there may be in vaccination comes from bacteria 
that get into the wound and not from the vaccination itself. 
B. It is best to be revaccinated every few years, and whenever 
one has been exposed to smallpox. 
q. Pure blood may not protect us from germs. CHAPTER TWENTY-SIX 
OTHER PROTOZOAN DISEASES 
In the tropics there are many protozoan diseases that 
are unknown in our country. Among these diseases 
is the slow and surely fatal sleeping sickness of Africa, 
which is estimated to have killed a half million people 
between the years 1896 and 1906. It is communicated 
to man by the bite of a fly, and in some villages from 30 
to 50 per cent of the people are affected. 
Another protozoan disease of hot countries (a severe 
malaria-like fever called kala-azar) is carried by the 
bedbug and probably also by the flea. Chronic dysentery 
is another very important protozoan disease, and there 
are a number of other diseases that are probably caused 
by protozoa, although the germs that cause them are un- 
known. In this chapter we shall study certain of these 
diseases that are of importance in the United States. 
RABIES (HYDROPHOBIA) 
Rabies is caused by a very small germ that is believed 
to be a protozodn. It grows especially in the brain and 
spinal cord and gets into the body usually from the 
bites of dogs or cats. In man the incubation period is 
never shorter than fourteen days; usually it is five or 
six weeks, and it may be a year. The germs are in 
the saliva three days (possibly eight days) before the 
animal shows symptoms of the disease. In their wild 
state, wolves, foxes, coyotes, and skunks may suffer from 
the disease. 
Preventing rabies. Practically all the rabies in our 
country comes from the bites of dogs, and by keep- 
128 OTHER PROTOZOAH DISEASES 
129 
ing dogs properly muzzled it is possible to stamp out 
the disease entirely, as has been 
done in several European coun- 
tries.1 It is a mistake to think 
that rabies develops in dogs be- 
cause of hot weather or lack of 
water. The dog gets the germ 
into its body from the bite of 
another dog, and dogs may 
suffer from the disease at any 
time of the year. A rabid ani- 
mal has a habit of scratching at 
its mouth to remove the tough 
saliva, and a wound from the claws of such an animal 
is therefore dangerous. 
The Pasteur treatment. There is no cure for rabies 
after the disease develops, but a preventive treatment 
has been discovered by a great Frenchman named 
1 The following statistics give the number of deaths from rabies in 
England and Wales for each year, from 1887 to 1907, and show clearly 
how muzzling dogs checks the spread of the disease: — 
Fig. 88. If all the dogs in our 
country could be muzzled for a 
few years, rabies would dis- 
appear. The dogs could then 
be unmuzzled without danger of 
the disease to man or beast. 
Year 
Deaths 
Muzzling again enforced 
1887 
• 29 
Year 
Deaths 
1888 
• 14 
1896 
. 8 
1889 
1897 
. 6 
Muzzling enforced 
1898 
1890 
. 8 
1899 
1891 
1900 
1892 
. 6 
1901 
1902 
Opposition to muzzling; 
1903 
ordinance not enforced 
1904 
. 0 
1893 
• 4 
1905 
, . 0 
1894 
• 13 
1906 
*895 
1907 ...... 130 
PRIMER OF SANITATION 
Louis Pasteur. This treatment is founded on the same 
principles as vaccination. Weak germs are put into the 
body, and by killing these weak germs the germicidal 
power of the body is increased. The body then goes on 
and not only kills the weak germs that have been put 
into it during the treatment, but kills also the germs 
that are in the wound made by the rabid animal. Thus 
the disease is prevented. The Pasteur treatment is 
successful in nearly all cases in which it can be com- 
menced in time. Where the materials for this treat- 
ment can be delivered within thirty-six hours after they 
are shipped, they can be sent by mail and the treatment 
can be given to the patient by his home physician.1 
Treatment of wounds made by rabid animals. A very 
great safeguard against rabies is to treat promptly all 
wounds made by the teeth of animals with something 
that will kill the germs in the wound. Any disinfectant 
(page 159) is useful, but burning with nitric acid is the 
most effective remedy. This should be done by a 
physician, to make sure that it is thoroughly done, and 
to guard against too great injury to the flesh by the 
acid. The best way is to wash the wound at once with 
1 There was formerly a curious superstition that certain stones, called 
“ madstones,” would prevent rabies. Some person in the community 
would possess one of these stones, and when any one was bitten by a 
rabid dog, the stone would be applied to the wound to “ draw out the 
poison.” It need hardly be said that madstones are of no use in prevent- 
ing rabies, and that intelligent persons long ago gave up their use. It is 
perhaps well to know that in several instances rabies is believed to have 
been caused by the use of a madstone. The stone became infected with 
the germs from the blood and saliva in wounds to which it had been ap- 
plied, and then, when placed on a wound made by a dog that did not have 
rabies, the germs were introduced into the wound and the disease 
was produced. OTHER PROTOZOAN DISEASES 
131 
turpentine, carbolic acid, bichlorid of mercury, or some 
other disinfectant, and then go to a physician. Treat- 
ment even after twenty-four hours is useful. It is easier 
for the body to kill a few germs than a large number, 
and a disinfection of the wound that kills even a part of 
the germs is a great help. An animal that has bitten 
any one should not be killed, but should be shut up 
until it is known whether or not it has rabies. If the 
animal remains in health for nine or ten days, there will 
be no occasion for worry. If it shows 
symptoms of the disease, it should be killed 
without injuring the brain, and the head 
should be sent to a Pasteur Institute or to 
a bacteriological laboratory. There the 
brain can be examined for the germs of 
rabies, and if they are found, it will be 
certainly known that the treatment should 
be begun at once. 
Fig. 89. The 
germ of dysen- 
tery. The dark 
bodies in the 
germ are red 
blood corpuscles 
on which the 
germ feeds. 
Acute dysentery (page 81) is caused by 
a bacillus that is closely related to the ty- 
phoid germ. There is a chronic form of 
dysentery, however, that is caused by a protozoon. This 
germ is much larger than most disease germs, and in 
many ways it resembles a large white blood corpuscle. 
Its life outside the body is not well known, but there 
is abundant evidence that the disease is usually con- 
tracted by drinking impure water. Infection seems to 
come also, at times, from eating raw vegetables that 
have been grown in polluted soil Chronic dysentery is 
CHRONIC DYSENTERY PRIMER OF SANITATION 
132 
more common in the southern than in the northern states, 
but cases of it occur in all parts of the country.1 
MEASLES 
Measles is a very infectious disease even in the early 
stages. The breaking out is not only on the skin but 
also in the eyes, throat, and air passages, and the germs 
are in the secretions from these parts. During an at- 
tack of measles the eyes should be rested, shaded from 
light, and bathed in boracic acid or other disinfectant 
several times a day, and the patient should have careful 
nursing and be protected from the germs of colds, in- 
fluenza, pneumonia, and tuberculosis; for, more than 
almost any other disease, measles weakens the resistance 
of the body to all germs, and many cases of bronchitis, 
pneumonia, and consumption follow an attack of this 
disease. The incubation period is very regularly from 
nine to eleven days, and the eruption usually appears 
the fourteenth day. This disease is much more danger- 
ous to children than to older persons, and the great ma- 
jority of deaths from measles is among children under 
five years of age. 
Measles is a far more serious disease than is generally 
supposed, and it should be strictly quarantined(page 207). 
A patient is dangerous as long as the discharges from 
the eyes and nose continue, usually for a period of about 
three weeks from the breaking out of the rash. In a 
house the germs die out in about two weeks. German 
1 Dysentery germs are abundant in the discharges from the bowels of 
any one who is sick with the disease. It is therefore very important that 
these discharges should be carefully destroyed (page 161), so that the 
germs may not be carried about by flies or in other ways. OTHER PROTOZOAN DISEASES 
133 
measles is supposed to be a different disease from ordi- 
nary measles, and one that is less severe. 
CHICKEN POX 
Chicken pox is usually a mild disease and seldom 
attacks any one but children. It is of importance 
mainly because mild cases of smallpox are often mis- 
taken for it. The incubation period is from thirteen 
to eighteen or nineteen days. 
SCARLET FEVER 
The germ of scarlet fever has not been discovered, 
but it is known that the discharges from the throat, 
nose, eyes, and ears are infectious, and the patient is 
dangerous as long as these discharges continue. The 
germs withstand considerable drying, but the scales 
from the skin are not infectious and the disease is not 
air-borne, as was formerly supposed. It is a difficult 
disease to control, because there are mild cases (“ missed 
cases”) of it that are not recognized and quarantined. 
The incubation period is from two to five days, and the 
patient is usually quarantined about fifty days. It at- 
tacks children especially, and a person usually has the 
disease but once. 
Scarlet fever is a very dangerous disease because 
there often goes with it a severe attack of the pus- 
forming bacteria on the kidneys, ears, eyes, throat, or 
other part of the body, and it is not uncommon for it to 
leave its victims deaf or blind, or in some way injured 
for life. It should, therefore, be carefully quarantined, 
and a close watch kept for the mild cases from which 
epidemics often spring (see footnote, page 205). 134 
PRIMER OF SANITATION 
PROTOZOAN DISEASES OF ANIMALS 
Texas fever, or “ tick fever,” a very severe malaria- 
like disease of cattle in the southern part of the United 
States, is due to a protozoon in the blood. This germ 
is carried from one animal to another by a kind of tick. 
Nagana is an African disease of animals, the germ of 
which is carried by a fly. This disease kills all horses 
and cattle over a large area in central Africa, and 
makes travel and agriculture very difficult in that 
region. Surra is a protozoan disease spread by the 
bites of flies that is fatal to great numbers of horses 
and cattle in India and other parts of southern Asia, 
in the East Indies, and in the Philippines. Protozoa 
are found also in the blood of rats; and birds, turtles, 
frogs, and many other animals are infected with them. 
POINTS TO BE REMEMBERED 
1. Rabies is due to a very small germ that attacks especially 
the brain and the spinal cord. 
2. Almost all the rabies in our country comes from dogs, and 
the disease can be stamped out by properly muzzling dogs. 
3. The Pasteur treatment will usually prevent rabies from de- 
veloping, if treatment is begun in time. 
4. A wound made by the teeth of an animal should be care- 
fully disinfected. 
5. Chronic dysentery is a protozoan disease and usually is 
contracted from polluted water. 
6. Measles and scarlet fever are dangerous diseases that should 
be strictly quarantined. 
7. Many diseases of animals are caused by protozoa. CHAPTER TWENTY-SEVEN 
INTESTINAL WORMS 
Intestinal worms are in no sense germs, for their 
bodies are composed of many cells, and some of them 
are animals of considerable size. Yet we shall briefly 
discuss some of the more important of them, because 
they afflict more people than is generally known, and 
because by proper sanitation they can be avoided. 
How important this subject is may be known wherl it 
is learned that in some tropical countries almost the 
whole population is infected with these worms, and that 
in some temperate countries examinations have fre- 
quently shown that from 30 to 50 per cent of the people 
of a community were infected with intestinal worms of 
one kind or another. Extensive studies of this subject 
made in the United States show that intestinal worms 
are much more frequent in the southern states and in 
California than they are in the northern states. 
EELWORMS 
Eelworms (•Ascaris lumbricoides) are large, yellowish 
white-worms, thicker than a lead pencil, and sometimes 
over a foot long. Many persons, especially children, 
suffer from them. The eggs are swallowed and hatch in 
the intestine. The young worms then make their way to 
the lungs, pass up the trachea to the throat, and reach the 
intestine again by being swallowed. There is evidence 
that the young worms damage the lungs and bring on 
attacks of pneumonia, and the adult worms cause nervous- 
ness and weakness. Several kinds of domestic animals as 
well as man are attacked by these worms, and the eggs are 
in the intestinal wastes of infected animals and persons. 
135 136 
PRIMER OF SANITATION 
PINWORMS 
The pinworm (Oxyuris) is a small white worm that 
grows mainly in the lower part of the large intestine. 
The disease is most common in children. The eggs 
are often on the hands of infected children; they may 
get into drinking water; or children, by playing in pol- 
luted soil, may get the eggs on the hands and into the 
mouth. Children that are infected should be treated, 
so that they may not infect others, and the soil about 
wells and houses should be kept free from pollution. 
WHIPWORMS 
The whipworm (Trichuris) is a slender white worm 
nearly two inches in length. The eggs get into the body 
by being swallowed. In some parts of Europe from 10 
to 30 per cent of the people are infected, and it is known 
that the disease is not at all uncommon in the United 
States. 
HOOKWORMS 
The hookworm (Necator) is white in color, of the 
thickness of a moderate sized sewing thread, and about 
one third of an inch in length. This worm is found in 
the warmer parts of the whole earth, Africa, India, 
China, Porto Rico, Guiana, Colombia, the Philippines, 
and many other places being heavily infected. Of more 
than 700,000 persons examined for hookworm in the 
southern part of the United States, 35 per cent were 
found to be infected, and it is estimated that there are 
two million people in this region suffering from the 
disease. The worms live in the small intestine and feed 
on blood which they suck from the wall. Much blood INTESTINAL WORMS 
137 
besides that which they use for food is lost through the 
wounds that they make; for they move about freely in 
the intestine and keep making fresh wounds in the wall. 
A person may carry any number of them from a very 
FIGS. 90 and 91. Hookworm victims. (After photographs by Dr. Charles W. 
Stiles, U. S. Public Health and. Marine-Hospital Service.) 
few up to several thousands, and severe cases of the 
disease may end in death. 
How hookworms get into the body. The eggs of hook- 
worms pass out of the alimentary canal, and if they are 
allowed to get into the soil, they develop into very tiny 
worms. These small worms usually enter the body 
through the skin (causing “ground itch,’’ “toe itch,” or 
“ dew sores ”), make their way to the lungs, crawl up the 
trachea to the mouth, and reach the intestine by being 
swallowed. They may also be taken into the intestine in 
water, or in food that is eaten with soiled hands. The 
worms do not multiply in the intestine, but they are 
known to live for more than six years and they probably 
live as long as ten years. Under favorable conditions, 
the young have been found to live in the soil for more 
than five months, but both the eggs and the young worms 
are killed by thorough drying and by freezing. 138 
PRIMER OF SANITATION 
Hookworm disease. The hookworm produces a toxin 
which poisons the body, and this with the loss of blood 
causes a marked anemia (lack of red blood corpuscles). 
Some of the prominent symptoms of the disease, which 
are especially marked in severe cases, are paleness, con- 
tinued weakness, mental dullness, dry skin and hair, 
dull, staring eyes, swelling of the limbs and face, and in 
young persons a stunting of the growth. Sometimes 
there is an appetite for such substances as earth, ashes, 
paper, coffee grounds, salt, and plaster. 
Where hookworm disease is most common. Hook- 
worm disease is most common on light and sandy soils 
(the kind of soil on which pine trees grow). It is more 
common among children than among adults, because 
children go barefooted, and sometimes eat with unwashed 
hands after playing in the earth; it is more common 
among miners, agricultural laborers, brickmakers, and 
railroad laborers than among those who do not come in 
contact with the soil; and the disease is more severe 
(though not more common) in the white than in the 
colored race. 
The prevention of hookworm disease. The eggs of 
hookworms get into the soil only from persons who have 
the disease. Away from the air, or in very wet soils, 
the eggs die, and the disease can be entirely prevented by 
the use of closets} Great care should therefore be taken 
to prevent the pollution of soils about houses. To a 
great extent children may be saved from infection by 
the wearing of shoes; but keeping the soil free from 
1 Of 189,586 country homes inspected by the Rockefeller Sanitary 
Commission, 95,988 had no closets at all, and 87,156 others had open 
closets that allowed the wastes to spread freely over the soil. INTESTINAL WORMS 
139 
pollution is the important measure in the prevention of 
hookworm disease (page 203). 
Weakness caused by intestinal worms. Hookworm 
victims are too weak to work effectively, and hundreds 
of thousands of persons are living in poverty and ig- 
norance because of this disease. Because these per- 
sons do not have the symptoms of ordinary sickness, 
it is often not realized that they are in a diseased con- 
dition, and their poverty is attributed to shiftlessness 
and laziness instead of to the true cause. 
The sapping of the vitality of the body by these 
small robbers also lessens the resistance of the body to 
tuberculosis and other germ diseases. An instance of 
the truth of this statement comes from the Philippine 
Islands. When American officials took over from the 
Spaniards the great prison in Manila, there were about 
4000 prisoners in it. Most of these prisoners seemed 
to be in fairly good health, but many of them died of 
diseases from which they should have recovered, and in 
spite of all the care of the authorities, the death rate 
was very high (about 70 a year for each 1000 prisoners). 
An examination with the microscope showed nearly all 
the prisoners to be infected with intestinal worms. 
Medicines were then given to kill the worms, and after 
that the death rate in the prison was little more than 
one sixth of what it had been before (falling to 12 a 
year for each 1000 prisoners). These facts show clearly 
that intestinal worms lower the resistance of the body to 
disease germs. 
Preventing the spread of intestinal worms. The first 
great step in preventing the spread of intestinal worms 
is to treat the persons who are infected with medicines to 140 
PRIMER OF SANITATION 
kill the worms. This will not only restore these persons 
to health, but it will stop the supply of eggs that infect 
others. Hookworm disease is especially easy to cure; 
for a few doses of a very simple remedy will entirely 
free a patient from the worms. 
The second great step in the prevention of the spread 
of intestinal worms is to build closets to receive the wastes 
from the alimentary canal, and to stop the pollution of the 
soil about houses and school grounds. This precaution 
alone will not only almost entirely prevent the diseases 
that are caused by intestinal worms, but it will in a great 
measure prevent the spread of intestinal diseases that 
are caused by germs. It is to be remembered that 
many persons who themselves show no signs of ill- 
health may be infected with intestinal worms, and all 
soil pollution about houses should be stopped. 
POINTS TO BE REMEMBERED 
1. Intestinal worms are far more common than has been 
generally supposed. 
2. The young of the eelworm develop in the soil and are 
swallowed in water. 
3. Pinworms may be spread by the hands or by water. 
4. Whipworms are swallowed in water. 
5. Hookworm infection is common in our southern states. 
6. The young worms get into the body either by passing 
through the skin or by being swallowed. 
7. This disease causes much poverty and ignorance. 
8. Hookworm victims fall an easy prey to other diseases. 
9. The disease can be prevented by preventing soil pollution. CHAPTER TWENTY-EIGHT 
THE IMPORTANCE OF SANITATION 
Suppose that on a certain day in every year all the 
people in a village of a thousand inhabitants had to 
march past a bag in which there were a thousand balls, 
and each person had to draw a ball from the bag. Sup- 
pose that in the bag there were as many white balls as 
there were persons in the village who would escape all 
germ diseases during the next year, and as many balls 
of various colors as there were persons in the village who 
during the next year would be attacked by germ diseases. 
Suppose also that as many of these colored balls were 
marked with black crosses as there were persons in the 
village who in the next year would die of diseases caused 
by germs. In an average American village, then, there 
would be in the bag two or three red balls for those who 
were marked for tuberculosis, the same number of green 
balls for the victims of typhoid, perhaps eight or ten blue 
balls for those selected for pneumonia, and a great num- 
ber of other balls of various colors for those who must 
suffer from some serious infectious disease, such as diph- 
theria, meningitis, influenza, whooping cough, measles, 
or scarlet fever. There would also be in the bag some 
six or eight balls marked with the fatal black cross, 
which meant that before the year was done whoever 
drew that ball would die because of germs. 
If all the people of a town had to go through a drawing 
like that described above, would there not be a great 
fear in the heart of every one lest he or some one whom 
he loved should draw a fatal ball ? And if some one 
should come to the village who could show the people 
what to do so that there would be only a few colored 
141 142 
PRIMER OF SANITATION 
balls and almost no balls with black crosses in the bag, 
would not the people help him and encourage him in 
every way? We are sure that they would gladly give him 
the money that he needed 
in his work, and that they 
would assist him as much as 
was in their power. 
The danger from germ dis- 
eases in the average Ameri- 
can town. In the average 
American town the people 
are in the same danger from 
germ diseases that they 
would be in if they had to 
go through a drawing of lots 
like the one described above. 
This you can readily believe 
after your study of former 
chapters of this book. In 
every town a certain number 
of people are stricken with 
infectious diseases each year. 
Each year we hope that neither we ourselves nor any 
one who is dear to us will be the victims of the germs, 
but who they will be it is never possible to teM. Victims 
there will certainly be, for neither by day nor by night 
do our small enemies rest, and year by year they take 
their toll from every village in the land. 
Our defenders from the germs. From the beginnings 
of history, man has been attacked by unseen foes, slain 
by hands that were invisible. In the last thirty years 
our enemies have been found out, their homes have been 
Fig. 92. Louis Pasteur. He dis- 
covered the Pasteur treatment for 
rabies and did more than any other 
one man to make clear to us the 
nature of germ diseases and to point 
out ways by which these diseases 
can be prevented. THE IMPORTANCE OF SANITATION 
143 
discovered, their ambuscades have been torn down, and 
the paths by which they reach us have, been traced 
out. We have now physi- 
cians and health officers who 
can tell us how to escape 
most of the germs that attack 
us. They have come to show 
us “ how to arrange matters 
so that there will be very few 
colored balls and almost no 
balls with black crosses in 
the bag.” Shall we work 
with these persons who can 
in great measure defend us 
from the germs that would 
attack us, or shall we refuse 
their aid and allow the germs 
to ravage and destroy, as 
they have done ever since man has lived upon the 
earth ? This is the question that each community is 
now being asked to decide. 
Sanitation. Sanitation comes from a Latin word (sani- 
tas) that means wholeness, or health. It is the science of 
how to preserve the health, especially the public health. 
To have our premises clean and free from flies and mos- 
quitoes, our milk and water supplies pure, and the air 
we breathe free from dust, is sanitary. To live among 
insects, dirt, and germs, to drink impure water and un- 
clean milk, and to allow germs to be spread abroad from 
the bodies of persons who are diseased, is insanitary. 
It is of interest to note that from the same Latin word 
from which sanitation comes, we get also our words 
Fig. 93. Lord Lister, an English 
physician, who showed how to keep 
wounds free from infection and thus 
made modern surgery possible. 144 
PRIMER OF SANITATION 
sanity and saneness (soundness of mind), and insanity 
(unsoundness of mind). Sanity and sanitation mean 
the same in their origin, and we might conclude that to 
practise sanitation is to act sanely and sensibly, while 
not to practise it is to act in a way that indicates either 
a lack of knowledge or a lack of wisdom. Certainly 
(since every one is anxious to escape disease) we should 
not be far from the mark if we spoke of a town that 
was clean and free from dangerous germs as a sensible, 
sound-minded town, and of a town in which the people 
lived amid dirt and germs as a foolish town. In former 
chapters of this book we have discussed the importance 
of keeping down dust, of having pure water supplies, 
and of destroying mosquitoes. We shall now study 
other measures that may be employed in making our 
homes and communities sanitary places in which to live. 
POINTS TO BE REMEMBERED 
1. Every year in every town a number of persons are attacked 
• by disease germs. 
2. Most cases of germ diseases can be prevented. 
3. Physicians and health officers can tell us how to escape 
these diseases. 
4. It is sensible to practise sanitation and, as far as possible, 
avoid germ diseases. CHAPTER TWENTY-NINE 
THE HOUSEFLY 
There is a belief among some people that flies are 
useful because they feed on wastes. No greater mistake 
could be made. Flies light on and walk over all manner 
of unclean matter, and then spread germs and unclean- 
ness over dishes, food, and milk vessels. They may 
come to our faces straight from feeding on the sputum 
of a consumptive or the wastes of a typhoid patient. 
They may fly directly from some one who has sore eyes 
to our hands or faces or to the very eyes of a little baby 
that cannot defend itself from them. There is nothing 
more dangerous or more unclean than to live among a 
swarm of flies. 
Kinds of germs carried by flies. Almost any kind of 
germ may be carried by flies. Not only do they carry 
germs on their feet, but when a fly feeds on matter that 
contains disease germs, the germs are found in the matter 
that comes from its alimentary canal. In one speck left 
by a fly that had been captured on the face of a leper, 
ii 15 leprosy germs were found. Tuberculosis germs 
and typhoid germs have also been found in fly specks, 
and there is no reason why,a fly that walks over or feeds 
on matter containing the germs of any disease should 
not spread abroad those germs (page 192).1 
Keeping germ-containing matter away from flies. A 
fly may get germs on its feet by walking on the skin of 
a patient who has smallpox, measles, scarlet fever, or 
1 A study of 415 flies showed them to be carrying from 550 to 6,600,000 
bacteria. The average was 1,250,000. Living typhoid bacilli have been 
found to remain in or on the bodies of flies for 23 days, and tubercle 
bacilli for 15 days. 
145 146 
PRIMER OF SANITATION 
erysipelas. It may easily take up dangerous germs from 
an open sore or ulcer. Flies are certain to become in- 
fected if they are allowed to feed on the sputum of a 
FIG. 94. This child is healthy and well, but flies may leave disease germs in 
his food. 
consumptive, pneumonia, influenza, or diphtheria patient. 
The wastes from typhoid, dysentery, and cholera infan- 
tum patients must be absolutely destroyed, or flies may 
carry the germs all over the vicinity and may endanger THE HOUSEFLY 
147 
the life of every one in the neighborhood. In general, 
it is unsafe to have flies about any person sick with an 
infectious disease, for there is always danger that by 
lighting on his hands or face, or on some article in 
the room, they will take up germs. 
Screening against flies. From what you already 
know you will realize the importance of screening 
against flies, of freeing our 
houses as much as possible 
from them, and of covering 
all food and dishes from flies. 
When any flies at all are in 
a house, a young child should 
aways be screened from them, 
for it is not right to leave a 
helpless little baby where it 
will not only be continually 
annoyed by flies crawling over it, but will have many 
different kinds of dangerous germs left on its face. 
Removing the breeding places of flies. By far the 
most effective way of dealing with flies is to remove 
their breeding places. The egg of the housefly is laid 
in manure (chiefly in horse manure, and almost entirely 
in fresh manure) about stables, and to some extent in 
dry closets, garbage, and decaying vegetable matter. 
In a day or less the egg hatches into a small, white, 
footless maggot, which in nine or ten days from the 
time the egg was laid changes into the adult fly. 
It is estimated that three hundred flies may hatch in 
a cubic inch of manure, and if the breeding places of 
the flies are left undisturbed, they will hatch faster than 
it is possible to kill them. It is a simple matter, how- 
Fig. 95. A baby should be 
screened from flies. 148 
PRIMER OF SANITATION 
ever, greatly to decrease their numbers by removing daily 
all matter in which they breed, burying it, or spreading 
it on the fields where it will dry and the eggs and 
young of the fly will be killed.1 They can also be kept 
from breeding in manure by covering it with lime, or 
sprinkling it with borax or a solution of hellebore in water. 
Fig. 96. The life history of the fly. A shows the eggs; B, the larva or 
maggot; C, the pupa; and D, the adult fly. 
A bulletin giving full directions for doing this may be 
obtained from the United States Department of Agricul- 
ture, Washington, D.C. Generally speaking, these meas- 
ures are more difficult and less effective than removing 
the manure before the maggots have time to mature. 
Killing adult flies. It is important to destroy flies 
that are already hatched; for the same flies may re- 
main about a house all summer unless they are trapped 
or killed. The giant flytraps, that are now bought or 
1 Floors of stables must be made of cement or other tight material; 
otherwise the flies will hatch in the crevices and in the earth that be- 
comes soaked with the liquid manure. Usually eggs are laid in manure 
before it is removed from the stalls, and if it is stored these eggs will hatch 
unless they are killed by lime or some other substance. THE HOUSEFLY 
149 
made, fly paper, poisons, and the fly swatter, are all 
useful in ridding a house of these pests.1 
The economy of fighting flies and mosquitoes. Under 
ordinary conditions it is not expensive to remove the 
FlG. 97. In a manure pile like this, millions of flies will breed. 
breeding places of flies and mosquitoes in a town, and 
no money that a town can spend will pay better, either 
1 The following hints may prove useful in the warfare on flies: Hang 
screen doors to open outward and rub them with a cloth dipped in 
kerosene or carbolic acid solution ; make tops of traps of wire or glass so 
that the flies will come up to the light; use bananas or bread and milk for 
bait; take away water and food, so that the flies will come to traps or 
materials placed for them; mix finely ground black pepper with hard 
boiled yolk of egg or add two tablespoonfuls of formalin to a pint of milk 
and expose to flies. Neither the pepper nor the milk with the formalin 
in it is poisonous to children or animals. The milk placed on porches 
where flies gather is particularly effective on hot, dry days. 150 
PRIMER OF SANITATION 
in dollars and cents or in the comfort that will come to 
the inhabitants, than money that is spent to free the town 
from these insects. In a small town one man can easily 
look out for all breeding places of mosquitoes. This 
will mean that there will be no malaria in that town; 
and there are many small towns that would have been 
large cities long ago if they had been free from malaria. 
A town cart can remove weekly all the matter in which 
flies breed, and this matter can be sold for fertilizer for 
almost enough to pay for the expense of removing it. 
Boards of trade often try to improve and advertise their 
towns. Suppose a board of trade could say: “ In our 
town you will not be bothered by mosquitoes, and neither 
you nor any member of your family will have malaria. 
You will not be annoyed by flies, and you need not 
fear that while you are looking the other way a fly will 
leave typhoid germs on your plate.” Would not a 
board of trade that could truthfully say this about its 
town have some facts to present that would interest 
persons who were seeking new homes ? 
POINTS TO BE REMEMBERED 
1. Flies are very unclean and can carry almost any kind of 
disease germs. 
2. Flies should not be allowed about sick people or about the 
wastes from the sick. 
3. Flies breed in manure and in other waste matter. 
4. These breeding places should be removed. 
5. Adult flies may be destroyed by traps, fly paper, poisons, 
and fly swatters. 
6. A town that is free from mosquitoes and flies has many ad- 
vantages over towns that are overrun with them. CHAPTER THIRTY 
DISEASE GERMS IN FOOD 
Foods (excepting milk) are not so likely as water to 
contain disease germs, but when foods become infected 
they are particularly dangerous, because germs can 
multiply in them. To appreciate this point you must 
understand that it is far more dangerous to take a large 
number of disease germs into the body than it would be 
to take a few germs of the same kind. A few dozen or 
a few hundred of almost any of the ordinary disease 
germs have no power to harm a rabbit when they are 
injected into its body, but if the dose is increased to sev- 
eral million germs, often the rabbit will die. Its white 
corpuscles and germicidal substances have the power to 
kill a few germs, just as the soldiers in a fort can drive 
away a small company of besiegers who are trying to 
break down the front gate of the fort. But when mil- 
lions of germs attack the body at once, the defenders of 
the body cannot overcome them, just as the defenders 
of the fort would be unable to resist successfully a great 
multitude of attackers, who would not only try to enter 
through the front gate, but at the same time would 
break down all the other gates and swarm over the 
walls at every point. It is because in many foods a 
single germ can increase to a multitude that our foods 
especially need to be guarded against infection. 
How germs get into foods. Not only the germs of in- 
testinal diseases, but also the germs of such diseases as 
tuberculosis, pneumonia, diphtheria, and scarlet fever, 
may reach the mouth in food. These germs get into 
the food from polluted soil, from flies, from washing in 
impure water the food or the vessels in which food is 
151 152 
PRIMER OF SANITATION 
kept, from diseased animals, and most commonly of all 
from the hands of those who are carrying germs. 
Fig. 98. Food that has been handled by the public is likely to contain germs. 
Those who prepare food should pay special attention 
to the cleanliness of their hands, washing them often 
with soap and water (page 161), and no one who is 
sick with an infectious disease or who is just recovering 
from such a disease, should have anything to do with 
the handling or the preparation of foods. 
Danger from spoiled food. Besides the germs of special 
diseases, there are always present in foods the bacteria 
that cause fermentation and decay.1 These bacteria do 
not ordinarily cause sickness in man, but when taken 
into the alimentary canal in the prodigious numbers in 
which they are found in foods that are beginning to 
1 If foods are cooked sufficiently to kill all bacteria in them (spores as 
well as the growing forms of the bacteria), and then sealed away from 
germs, as is done in cans, they may be preserved for years without decayc 
Strong salt solutions (brine) will also preserve foods, and strong sugar solu- 
tions, such as are used in preserving, will prevent the growth of germs in 
food. DISEASE GERMS IN FOOD 
153 
spoil, they cause fermentation in the intestine, diarrhea, 
and other troubles. Tainted and soured foods are there- 
fore unsafe and should never be eaten. 
Buying foods. The wise person buys his food in a 
store that is kept clean and where the food is protected 
from dust and flies. He never buys old and tainted meats 
or fish, or overripe or decaying fruits or vegetables, for 
these are swarming with bacteria and are already unfit 
for use. Above all, he will not buy any food that has 
been fingered over and handled by the public, for there 
is always danger that on such foods disease germs 
have been left from the fingers of some sick or germ- 
carrying person. 
The care of foods. In the care of foods two points are 
of especial importance. These points are cleanliness to 
prevent germs from getting into food, and cold, to keep 
germs that do get into the food from multiplying. The 
importance of cooking to kill any disease germs that 
may be in foods, as well as to kill certain worms that 
may be in meats, will of course be understood. It should 
also be understood that by thorough cooking all bacteria 
of every kind in food may be killed, and that food may 
be preserved in this way until a new supply of them 
has time to grow. 
Dangers from milk. Of all foods that are used by 
man, milk is the most dangerous, because without any 
cooking it furnishes a splendid place for the growth of 
almost all kinds of germs. Tuberculosis is sometimes 
contracted from milk, and it is known that typhoid fever, 
scarlet fever, and diphtheria may be spread by milk. 
Again and again it has been found that along the route 
of a certain milkman the people were suffering from 154 
PRIMER OF SANITATION 
one of these diseases, and on investigation it would be 
proved that a case of the disease existed among those 
handling the milk or in their families; or that the bot- 
tles had been taken back from families where the dis- 
ease was; or, in epidemics of typhoid fever, that the 
milk vessels had been washed in water from wells con- 
taining the typhoid germ. One article in a medical 
journal reported 330 epidemics traceable to milk, of 
which 195 were typhoid epidemics, 99 were epidemics 
of scarlet fever, and 36 were diphtheria epidemics. No 
person who has consumption, or who has recently re- 
covered from typhoid fever or other germ disease, should 
have anything to do with the milking of cows or the 
handling of milk. In general, the safest milk is that 
which is bottled at the dairy where it is produced. If 
possible, milk should be secured from a dairy that is 
known to collect and bottle its milk under sanitary con- 
ditions. It is difficult for a private citizen to guard 
against dangers from milk, and in all well-governed 
cities a health officer looks after the milk supply. 
Milk and cholera infantum. Most cases of cholera in- 
fantum are due to germs that are in milk.1 Sometimes, 
as we have already learned (page 84), it does not seem 
to be any one special germ that is causing this disease, 
but the enormous number of many different kinds of 
bacteria that are in the milk in hot weather. Only pure 
milk is a fit food for babies, and milk that is filled with 
a multitude of bacteria and their poisonous toxins is 
unsafe. Especially in the months when babies are 
weakened by heat is a pure milk supply important. 
l Of 9111 infants that died during one year in a large European city, 
only 844 were fed entirely on their mothers’ milk. DISEASE GERMS IN FOOD 
155 
Fig. 99. Dairies should be models of cleanliness, 
Keeping milk free from germs. All milk vessels and 
feeding bottles for babies should be thoroughly scalded 
before using to kill the bacteria in the milk that adheres 
to them. Otherwise these bacteria will multiply in the 
new milk, and soon it will be filled with them (page 18). 
Milk vessels should never be rinsed in any but boiled 
water, the purest of rain water, or artesian water, for 
one dangerous germ that gets into the milk from the 
water remaining on the vessels may grow into a mul- 
titude. Milking should be done in a clean building 
that has fly screens on it, and everything possible should 
be done to keep dust and hairs out of the milk, for 
these are loaded with bacteria. The milk should be 
cooled as quickly as possible, and kept cool to prevent 
the germs that do get into it from multiplying. It should 156 
PRIMER OF SANITATION' 
be used before it becomes old, for milk that at first has 
only a moderate number of bacteria in it may soon be 
filled with countless myriads of them. It is also neces- 
sary for a medical officer to examine the cows from which 
the milk comes, or there will frequently be living tuber- 
culosis germs in the milk (page 59). 
Killing germs in milk. When it is impossible to obtain 
pure milk, it is often best to “ Pasteurize ” the milk before 
it is used.1 This is done 
by heating it to 145 de- 
grees and holding it at 
this temperature for thirty 
minutes. This heating 
kills all disease germs and 
nearly all the other bacte- 
ria in the milk, and the 
person who uses the milk 
has fewer germs to re- 
sist. A few children do 
not digest Pasteurized 
milk as well as they do 
raw milk, and Pasteurizing old milk that is already filled 
with acids and toxins from the bacteria that are swarm- 
ing in it will not make this milk a fit food for a little child. 
In summer, however, most of the milk sold in cities is 
greatly improved by Pasteurization, and it is of no small 
advantage that all the tuberculosis, typhoid, diphtheria, 
and other dangerous germs that are in the milk are 
Fig. ioo. A vessel arranged for Pasteur- 
izing milk. Very convenient Pasteurizers 
for use in the home may be purchased at 
a low price. 
1 Recently many great epidemics of very severe sore throat. (septic sore 
throat) have been traced to infected milk. The disease is caused by a 
streptococcus that causes inflammation in the udder of the cow. Cows 
probably get the infection from the hands of persons who have the disease. DISEASE GERMS IN FOOD 
157 
killed. In fact, so much disease has been found to be 
due to milk that many health officers believe that all 
milk should be Pasteurized before it is put on the mar- 
ket, and that the sale of raw milk should be forbidden. 
It should be understood that although disease germs in 
milk are killed by Pasteurizing it, certain hardy kinds of 
bacteria and many bacterial spores are not killed by the 
process. After milk is Pasteurized, it should be cooled 
at once, or these surviving forms will quickly multiply 
and cause it to spoil. 
1. Infected foods are particularly dangerous because disease 
germs can multiply in food. 
2. Germs can get into foods from flies, impure water, and 
from the hands of persons who are carrying germs. 
3. Spoiled foods are unfit for use. 
4. Foods that have been handled by the public, or exposed to 
flies, should not be purchased. 
5. Cleanliness and cold are the points to be emphasized in 
caring for foods. 
6. Impure and unclean milk is the most dangerous of all 
foods; tuberculosis, typhoid fever, scarlet fever, and diph- 
theria may be contracted from it. 
7. Cholera infantum is usually caused by unclean or old milk. 
8. Milk vessels should be carefully scalded and should be 
rinsed only in pure water. 
9. Milk should be collected in as cleanly a manner as pos- 
sible and cooled quickly to prevent the multiplication oi 
germs in it. 
10. When milk contains many bacteria, it is usually advisable tc 
Pasteurize it before giving it to a little child. 
11. Many health officers believe that all milk should be Pas 
teurized before it is sold or used. 
POINTS TO BE REMEMBERED CHAPTER THIRTY-ONE 
DISINFECTION 
It cannot be too strongly emphasized that nearly all 
the germs that cause disease in man come from persons 
who have germ diseases, and that insects, water, and 
food are dangerous only when they have become infected 
with germs from some human being. In preventing the 
spread of infectious diseases, therefore, the most impor- 
tant point is to destroy the germs that come from the 
bodies of the sick. 
Light. Light is destructive to bacteria, and bright 
sunlight kills many kinds of germs in a few minutes. 
It is an excellent practice to expose bedclothes and rugs 
to the sun, and to throw up the shades and allow the 
sunlight to enter the house. In rooms occupied by 
consumptives or by pneumonia, diphtheria, or influenza 
patients, this is especially important. 
Drying. Drying checks the growth of all germs, and 
most germs die if they are thoroughly dried. Damp 
houses keep alive the germs that are in them, and con- 
sumption, pneumonia, and other diseases are more likely 
to develop in damp than in dry houses. Dirt and dust, 
mingled with sweat and oil from the skin, on doorknobs, 
banisters, and furniture, protect germs from light and 
keep them alive. For this reason the doorknobs and 
desks in schoolrooms should be cleansed occasionally 
with soap and hot water. 
Heat. Boiling water kills the germs of all common 
diseases, and handkerchiefs, dishes, and clothing that 
have become infected can be made safe again by thor- 
oughly boiling them. Sputum and articles of little 
value may often be most conveniently disposed of by 
158 DISINFECTION 
159 
burning (page 56). The surfaces of dishes contain tiny 
crevices in which germs lodge, and in disinfecting dishes 
with hot water, it is necessary to leave them for a few 
minutes in water that is boiling, so that the heat will 
reach the germs in the crevices. 
Chemical disinfection. Certain chemicals are so poison- 
ous to germs that they are extensively used in disinfect- 
ing. A physician should always be consulted as to which 
disinfectant is best for a particular purpose, and exactly 
how to use it, for some of them are better for one pur- 
pose than for another. Most disinfectants are very 
poisonous, and a little red ink or other coloring matter 
should be added to them so that they will not be mis- 
taken for water. The following are some of the most 
common disinfectants: — 
Bichlorid of mercury (corrosive sublimate) dissolved in 
water, with one part of the bichlorid to a thousand parts 
of water (1 ounce to 8 gallons of water), kills nearly all 
kinds of germs in two or three minutes. This disin- 
fectant can be purchased in tablets of the right size to 
make a pint or half a pint of the solution. For the hands, 
for washing floors and furniture, and for disinfecting 
clothing that can be soaked in it, this is an excellent 
disinfectant. It cannot be used on metals, as it destroys 
them, and it is not good for disinfecting where there is 
much organic matter present, as there is in sputum and 
in the discharges from persons sick with typhoid or 
other intestinal diseases. It is very poisonous. 
Biniodid of mercury is more than twice as powerful as 
bichlorid of mercury, and need be made only half as 
strong. It is one of the best general disinfectants, and 
is especially useful in disinfecting the hands, since it 160 
PRIMER OF SANITATION 
does not injure the skin. It can be used on metals, and 
is useful for disinfecting instruments. 
Carbolic acid, made up in a 2|- per cent solution 
ounces of liquid carbolic acid to a gallon of water, or 
seven teaspoonfuls to a pint), is a good disinfectant. 
For disinfecting sputum and other discharges from the 
body it is well to use a 5 per cent solution. 
Lysol is a stronger disinfectant than carbolic acid. 
It often destroys the colors in clothing. For sputum it 
is one of the best disinfectants. 
Chlorid of lime, used in the proportion of 4 ounces of 
chlorid of lime to 3 gallons of water, is a cheap and 
powerful disinfectant. It may be purchased in grocery 
stores, put up in tin cans under the name of bleaching 
powder. It cannot be used on colored clothing, and 
the solution must be freshly made. 
Milk of lime is a powerful disinfectant. To make the 
solution, add one part of freshly slaked lime by weight 
to four parts of water; or add the hard lumps of quick- 
lime to the water and stir until a thick whitewash is 
formed. This is a cheap disinfectant, and for disinfect- 
ing the body wastes it is as good as anything that can 
be used. It should not be used in sinks, for it will cause 
trouble with the traps. Air-slaked lime (lime that has 
crumbled into fine powder from contact with the air) is 
worthless, and only quicklime should be used. 
Special points in disinfecting. In caring for a case of 
infectious disease it is well to understand the following 
special points in disinfection: — 
Disinfecting the hands. Any one who is caring for a 
person sick with an infectious disease should frequently 
sterilize his hands by holding them in a disinfectant. DISINFECTION 
161 
Washing the hands thoroughly in a soapy lather will 
almost free them from germs, 
and before eating they should 
be washed in this way and 
then disinfected. Keeping 
the nails trimmed and the 
skin smooth makes the hands 
much easier to disinfect. The 
hands of a person who is 
sick with a germ disease 
should frequently be washed 
with soap and water, and 
should be disinfected occa- 
sionally. 
Disinfecting body wastes. 
In typhoid fever and dysen- 
tery, the discharges from the intestines and kidneys 
should be received in vessels containing disinfect- 
ants. A strong solution of either chlorid of lime or 
milk of lime is excellent for this purpose. If is neces- 
sary to see that the disinfectant is thoroughly mixed 
with the waste matter, and it should be allowed to stand 
for several hours to make sure that all germs are killed. 
Any matter that is vomited by the patient may contain 
the germs, and should be treated in the same way as the 
intestinal and kidney discharges, and all handkerchiefs 
that a patient may use should be put into hot water or 
a disinfectant. The wastes from the alimentary canal 
should be disinfected in consumption and other respira- 
tory diseases as well as in intestinal diseases. Even 
where there is water sewerage and these wastes can be 
thrown into the closet with little danger to the family 
Fig. ioi. Washing the hands thor- 
oughly with soap and water helps 
to free them from germs. 162 
PRIMER OF SANITATION 
of the sick person, still they ought to be disinfected; 
for the germs may reach the water supply of another 
town, and some one may suffer from them. 
Disinfecting in diseases where germs are in the nose 
and mouth. In diphtheria, pneu- 
monia, consumption, influenza, 
measles, scarlet fever, and epi- 
demic cerebro-spinal meningitis, 
the germs are in the discharges 
from the throat and nose. The 
instructions given on page 56 for 
disinfection in cases of consump- 
tion apply in all these diseases. 
Disinfecting buildings. Where 
a room or whole house is to be 
disinfected, it is usually done 
by fumigating. Formaldehyde is 
best for this purpose. Special 
directions are necessary for this 
work if it is to be done effec- 
tively. Quicklime is a good dis- 
infectant for cellars and closets. 
Mistaken ideas in regard to dis- 
infection. It is a common idea 
that there is some connection be- 
tween the smell of a substance and 
its power as a germ-killer . Strong- 
smelling substances are sometimes 
burned in sick rooms, or a little 
carbolic acid is exposed in a saucer, so that it will scent 
the air of the room. It need hardly be pointed out that 
germs are not injured by anything of this kind. 
no isolation 
or disinfection 
isolation and 
disinfection 
Fig. io2. In Michigan, from 
1890 to 1903, there were on 
an average 43.4 cases in 
each outbreak of measles 
where isolation and disinfec- 
tion were not practised; in 
each outbreak where these 
measures were put in force, 
there were, oil an average, 
only 2.9 cases. (From re- 
port of Michigan State 
Board of Health.) DISINFECTION 
163 
The importance of disinfection. Our second great law 
for the prevention of germ diseases was to keep germs 
from the bodies of the sick from being scattered abroad. 
This can be done only by disinfection, and if all families 
would learn the value of disinfection and practise it, 
perhaps the most important step in the prevention of 
germ diseases would be taken. 
Isolating the sick. People need to learn that sick 
persons should be kept away from those who are in 
health. This is best for both the sick and the well. It 
is possible to practise disinfection efficiently only when 
a sick person is kept in a room by himself, and the 
careless visiting in sick rooms which is allowed in col- 
leges, boarding schools, and most families, is a cause 
of much disease. Figure 102 shows how effective isola- 
tion and 'disinfection are in checking the spread of 
measles, one of the most infectious of all diseases. 
POINTS TO BE REMEMBERED 
1. Disease germs come from the bodies of diseased people. 
2. Light and drying kill germs. 
3. Heat is an excellent disinfectant. 
4. Certain chemicals poison and kill germs. 
5. A physician should be consulted as to the best disinfectants 
to use for particular purposes. 
6. There is no reason to think that a substance is of any value 
as a disinfectant because it has a strong odor. 
7. Disinfection and isolation are very important measures in 
checking the spread of germ diseases. CHAPTER THIRTY-TWO 
UNHYGIENIC HABITS 
As we have said again and again in former chapters, 
nearly all disease germs leave the body by way of 
the mouth and 
nose, or in the 
wastes from 
the alimentary 
canal and kid- 
neys, and most 
of them get 
into the body 
through the 
mouth and the 
nose, espe- 
cially through 
the mouth. In 
their daily life, 
many persons 
have fallen 
into certain 
habits that 
make it easy 
for germs to 
get into the 
mouth and 
nose, and into other habits that scatter germs abroad 
where they are likely to do harm. 
Putting objects into the mouth. The habit of putting 
into the mouth pencils, coins, candy, chewing gum, or 
any other object that has been in the mouth of another 
person, gives germs an opportunity to pass directly from 
Fig. 103. It is never safe to use public drinking cups. 
164 UNHYGIENIC HABITS 
165 
one mouth to another. A public drinking cup on a 
train, at a public fountain, or in a school, is certain 
to be used by some one with disease germs in his mouth.1 
If another person then drinks from the cup, the germs 
have as good an opportunity as a germ could wish to 
pass into the mouth unweakened by drying. Each 
pupil in a school should have his own cup, and a private 
cup should always be carried when traveling; but if it 
is necessary to drink from a public cup, it is best to put 
both lips into the cup while drinking. This is because 
the germs are more likely to be sticking to the edge of 
the cup (in mucus from the 
lips of persons who have pre- 
viously used the cup) than 
to be floating free in the 
water. 
Putting the hands to the 
face. Another habit that we 
would mention is that of al- 
lowing the fingers to touch 
the face, eyes, or lips. In 
many ways — from books, 
doorknobs, pencils, seats, and 
straps in street cars, and from the hands of other per- 
sons— we get germs on our hands. It is advisable, 
therefore, to form the habit of keeping the hands away 
from the face. Especial attention should be given to 
this point when sore eyes are prevalent. Before eating, 
Fig. 104. Rubbing the eyes and 
putting the hands to the face are 
bad habits. 
1 On a drinking glass that had been touched by the lips, 20,000 bacteria 
were found, and 5000 on a glass slip touched by a thumb moistened with 
saliva, as the leaves of a book are often touched with a moistened finger 
or thumb in turning them. 166 
PRIMER OF SANITATION' 
the hands should be thoroughly washed with soap, for 
this is a very wonderful remover of germs. 
Exchanging books in the schoolroom. Where school- 
books are furnished by the town or state, they are some- 
times given out each morning, and it is only by chance 
that a pupil receives the same book on two successive 
days. This is not right, for the germs of diphtheria, 
pneumonia, scarlet fever, and of other dangerous dis- 
eases may be spread through a school by the books. 
Each child should keep the same books throughout the 
year, and passing books about from one pupil to another 
should be discouraged. It might be added that writing 
paper is more sanitary than the slates that are still in 
use in some places, for slates are often wet with saliva, 
and the sponges that are used on them are generally 
reeking with germs. 
Drinking water to which one is not accustomed. When 
one is away from home on a short journey (as on a visit 
to a city or to an exposition), it is often not possible to 
be sure whether the water that is provided for drinking 
purposes is safe or not. It is, therefore, the part of 
wisdom to take a supply of water from home, or to drink 
mineral water or boiled water, or even tea or coffee. 
By drinking water from various sources, while on their 
vacations, hundreds of people every summer contract 
typhoid fever. Strangers coming into a place that has 
an impure water supply are always far more liable to 
contract typhoid fever than the inhabitants of the 
place, who are accustomed to the water, and almost any 
strange water is likely to cause intestinal disturbances 
that may spoil all the pleasure of a short visit or excur- 
sion. UNHYGIENIC HABITS 
167 
Spitting. In previous chapters your attention has 
been repeatedly called to the fact that many germs 
may be in the mouth. That these germs are certainly 
scattered about by spitting, every one must understand. 
Tobacco spit is as bad as any other kind of spit, and every 
one must learn that to spit at all is not only an unclean 
and disgusting habit, but one that is very insanitary. 
Many cities have laws against spitting in public places. 
These laws are founded on common sense and should 
be supported by all good citizens. Every one should 
at least have enough care for others to spit in the gutter 
and not on the sidewalk, for on the sidewalk the germs 
are almost certain to be carried on the feet of passers-by 
into houses, stores, and offices. 
Washing the teeth in wash basins. Cleaning the 
teeth in a wash basin will leave any germs that may be 
in the mouth in the wash basin, and you will readily 
understand how easy it would be for a few hundred 
thousand of these germs to get to the mouth of some one 
else who washes his face in the basin. A bathroom 
should have a sink over which the teeth may be cleaned, 
and in cars and public wash rooms some other place than 
the wash basins should be provided for cleaning the 
teeth. In a public wash room the safest plan is to turn 
on the water and wash in the stream as it comes from 
the faucet. 
Scattering the germs of intestinal diseases. We come 
now to one of the most important and the most difficult 
of all the questions of sanitation, the question of how to 
prevent the spread of the germs of intestinal diseases. 
It is utterly amazing the way these germs now get 
scattered abroad, and the more we study the subject 168 
PRIMER OF SANITATION 
the more we realize how unclean a creature man really 
is; for we must remember that every one of the million 
of cases of intestinal diseases that occur yearly are 
caused by germs that have escaped from the human 
body in the wastes from the alimentary canal and kid- 
neys. In towns and in the country, where there is no 
water supply, the greatest care must be taken in dispos- 
ing of these wastes, or disease will surely come from 
them. Where a city is supplied with water and has a 
sewer system, it is not difficult for a person or a family 
to know how to dispose of these wastes; but if the city 
disposes of its sewage by running it into the nearest 
stream, the people down the stream will probably suffer. 
The danger of polluting soils. In the last few years 
a very important discovery has been made. This dis- 
covery is that it is not an uncommon thing for healthy 
persons to carry very dangerous germs, and that the 
germs of all the infectious diseases of the intestine 
(cholera, typhoid, dysentery, and diarrhea) may be car- 
ried by persons who are not themselves ill (page 79). 
So many cases of intestinal diseases come from well 
persons, that it is unsafe to allow the soil about a house 
to be polluted by the wastes of any human being, 
whether he be sick or well. If the soil does be- 
come infected with dangerous germs, these germs will 
be carried about by flies, they will be taken by the 
feet into houses and to well platforms, and sooner or 
later they will almost certainly reach the mouths of 
others. Also, the intestinal worms (page 135) that are 
so great a scourge in the southern part of the United 
States are spread entirely through the pollution of the 
soil. It is perfectly evident that no wastes from the UNHYGIENIC HABITS 
169 
human body should under any circumstances be allowed 
to touch the soil of dooryards. Closets where these 
Fig. 105. Children often become infected with disease germs by playing In 
unclean places. 
wastes can be kept from becoming scattered and the 
germs in them can be destroyed, should be built.1 
Allowing children to play in the dirt. It is the chil- 
dren, more than any other persons, who suffer from germ 
1 The discharges from the kidneys are dangerous as well as the intestinal 
discharges, for they very commonly contain streptococci, and they may 
contain the bacilli of typhoid fever. 170 
PRIMER OF SANITATION 
diseases. One reason, and doubtless the main reason, 
for this is that children have less resistance to these dis- 
eases than have those who have grown up. Another 
reason is that children crawl and play on the door and 
earth where their elders spit, and where all kinds of 
dangerous germs are left by the feet of those who have 
walked on the streets or on polluted soil about the house. 
Babies should not be put down to play on dirty floors or 
in dirty yards, nor should they be allowed to put into 
their mouths objects that have been soiled by dropping 
them in such places. More than any one else little 
children need to be guarded against germs, and for 
their sakes, especially, floors and yards should be kept 
as clean as possible. 
POINTS TO BE REMEMBERED 
1. Many people have fallen into habits that make it easy for 
germs to get into the mouth and nose. 
2. Putting objects into the mouth, drinking from public cups, 
allowing the fingers to touch the face and lips, and drink- 
ing water from unknown sources, give germs an oppor- 
tunity to enter the body. 
3. Spitting, cleaning the teeth in wash basins, and polluting 
the soil are practices that scatter disease germs. 
4. The disposal of sewage and the prevention of soil pollu- 
tion are among the most important questions in all sanita- 
tion. 
5. Children should not be allowed to play in the dirt, for 
children, more than older persons, suffer from germ 
diseases. CHAPTER THIRTY-THREE 
PUBLIC SANITATION 
The wild man of the forest lives to a great extent 
alone, but civilized people cannot be independent of 
each other. Civilized people therefore have govern- 
ments. The advantages of having a government are 
so many and so great that no person of intelligence 
can fail to understand them. Many persons, however, 
fall into the habit of complaining about their taxes, and 
fail to understand that the government is a great part- 
nership into which all the people have entered for the 
good of all, and that for no other money expended 
do they get so much in return as for the money 
paid to the government. We will therefore turn 
away for a short time from the study of sanitation 
while we try to get a clearer idea of the advantages 
that come from having a government — advantages so 
plain that they have caused every civilized people that 
has ever existed on the earth to establish a government. 
The advantages of government. Each person who 
walks the streets of a city cannot hire a policeman to 
protect him, and it would not be possible for every 
family to own a fire engine. Every farmer who wishes 
to drive over the country cannot afford to build roads 
and bridges wherever he may wish to go, and only a 
few families have enough wealth to pay the entire cost 
of a capable teacher for their children. But if each 
family will pay but a small sum into the public treasury, 
the government can provide police and fire departments, 
look after the roads, and educate the children of all the 
people. A government is of advantage to the people 
who live under it because at a small cost to each person it 
171 172 
PRIMER OF SANITATION' 
gives to its citizens many advantages that they could not 
have in any other way. 
In a city firearms should not be used, and automobiles 
and wagons should not be driven too rapidly through 
crowded streets, because if this is done, many accidents 
are sure to occur. In the country, a farmer should not 
turn his cattle and horses out on the public road, for they 
may injure his neighbor’s crops. Yet no one person has 
authority to lay down rules in regard to the way another 
shall use a gun or drive an automobile or a wagon, and 
one farmer cannot force another to keep his cattle off 
the roads. Only a government with authority over all 
the people can do this, and it is a great advantage to 
have a government that can forbid every one's doing 
those things that are harmful to the welfare of others ; for 
there have always been and are now in the world many 
persons who have little regard for the rights of others. 
Government a partnership. From the above you will 
see that in reality a government is a great partnership. 
Each partner (citizen) is forbidden to do those things 
that would be injurious to others, and each partner 
is required to pay a certain sum of money (his taxes) 
into the public treasury each year. With this money 
the government hires done those things that are neces- 
sary for the welfare of all. One of the first duties of a 
government is to guard the health of its people, for as 
long as a community is greatly afflicted with disease, it 
cannot make much progress and its people cannot have 
much happiness. 
The need for public health officials. It is not possi- 
ble for an individual to protect himself from disease if 
those about him are carelessly scattering germs abroad PUBLIC SANITATION 
173 
Only some one with authority over all the people can 
guard the health of a community, and public health 
officials are absolutely necessary if sanitary measures are 
to be enforced. Only those who have been specially 
trained for the work have the skill that is necessary to 
fight infectious diseases successfully, only those who are 
paid to do so can give to the work the time and attention 
that are required to make the fight successful, and only 
those with authority to do so can compel careless and 
unclean citizens to live in a sanitary manner. With- 
out health officials certain persons in every community 
will keep breeding places for mosquitoes, hatch swarms 
of flies in great manure piles on their premises, spit on 
the sidewalks and in other public places, neglect to be 
vaccinated, or go straight out among the people from 
cases of very dangerous and very infectious diseases. 
Without officers of the law certain bad citizens always 
rob and steal, and these citizens must be forced to let the 
property of others alone. So in matters of sanitation, 
the ignorant and the careless citizens must be forced to 
live so that they will not be a source of danger to those 
about them. 
Supporting health officials. No thief thinks well of 
the policeman who arrests him, and no murderer loves 
the judge who sentences him to be hanged. So the 
persons who are compelled to clean up their premises 
and live so that they will not be a nuisance and a source 
of danger to their neighbors often become angry with 
the health officials and try to injure them and hinder 
their work.1 It is therefore the duty of every one to 
1 The greatest problem of the health official is the influential citizen who 
opposes any measures that may inconvenience him and on his right to 174 
PRIMER OF SANITATION 
assist and encourage health officials, and we should 
always remember that they are trying to save us and 
not themselves from disease. Whatever they do is 
done for the good of the people over whom they are 
watching, and no man can claim to be a good citizen if 
he deliberately hinders one who is trying to save helpless 
men and women and innocent little children from disease 
and death. Especially should a man who claims to be 
a good citizen, stay in quarantine when he is ordered 
to do so. For deliberately to scatter abroad disease 
germs is a crime, and the man who does it knowingly 
deserves to be treated as other criminals are treated. 
The economy of public sanitation. Many persons agree 
that public sanitation is a good thing, but think that the 
town or state in which they live cannot afford it. These 
persons do not understand what preventable diseases are 
costing their communities, or they do not understand 
political economy. For any man can afford to spend 
two dollars if thereby he can save ten dollars, and any 
community that spends money on public sanitation will 
save far-more in the time that has been lost on account 
of sickness than it spent in trying to preserve the health 
of its citizens. The typhoid epidemic at Plymouth, Penn- 
sylvania, cost nearly $100,000, and the persons who died 
in it were earning in wages $18,000 a year. Lawrence, 
Massachusetts, put in a water filter, and in four months 
the filter prevented enough typhoid to pay for itself. 
If the American people would use one half the sum that 
tuberculosis is costing them each year in fighting the 
disease, it is probable that tuberculosis would soon cease 
be a menace and a nuisance to all his neighbors. — An American Health 
Official. , PUBLIC SANITATION 
175 
to exist. A conservative estimate places the cost of pre- 
ventable germ diseases in this country at $1,500,000,000 
a year, and if this money were used in fighting these dis- 
eases, most of them would soon be practically stamped 
out. The United States government appropriated 
$100,000 to destroy rats around San Francisco, and 
some persons thought that this was a great sum of 
money to spend for such a purpose. Yet the rats them- 
selves, to say nothing of the plague that they carry, do 
six hundred thousand dollars’ worth of damage every 
year in a city like San Francisco, and in the whole 
country they do fifty million dollars’ worth of damage. 
Many towns everywhere think they cannot afford a 
public water supply, and yet every few years each one 
of these towns pays out more than the cost of a water 
system because of intestinal diseases. One such town the 
writer knows, a town of about two thousand inhabitants. 
Every year this town has from twenty to thirty cases of 
typhoid fever (besides other intestinal diseases) with two 
or three deaths, and every two years the people of the 
town spend enough on typhoid fever alone to pay for 
the water system that they think they cannot afford. 
Count up the number of cases of typhoid fever, the 
number of cases of consumption, or the number of 
persons who suffer from malaria in your town, and see 
if the people of the town are not acting in a very ex- 
travagant manner when they neglect public sanitation. 
You will certainly find this to be the case. 
The common sense of sanitation. In a former chapter 
(page 144) we spoke of the sanity of sanitation. At this 
time we wish to call attention again to the fact that it is 
foolish to live in a way that we know will lead to dis- 176 
PRIMER OF SANITATION 
ease. It is cheaper to live in a town where the side- 
walks are clean, the streets sprinkled, the houses supplied 
with pure water, the sewage safely cared for, the milk 
supply clean, flies and mosquitoes banished, and skilled 
health officers employed to watch for and prevent infec- 
tious diseases, than it is to live in an insanitary town. It 
is certainly more pleasant to live in a clean than in an 
unclean town ; at least it is more pleasant to be well in a 
clean town than it is to be sick in an unclean one. The 
only sensible thing for any community to do, therefore, 
is to have public sanitation, and free itself as much as 
possible from germ diseases. 
POINTS TO BE REMEMBERED 
1. In civilized communities no one lives to himself, and gov- 
ernments are necessary. 
2. Governments give to their citizens many advantages that 
they otherwise could not have, and they prevent the igno- 
rant and selfish citizens from harming others. 
3. In a government each citizen is a partner. 
4. The preservation of the public health is one of the first 
duties of a government. 
5. Public health officials are necessary to carry out sanitary 
measures. 
6. Good citizens should support health officials. 
7. Sanitation is economical, for it is cheaper—very much 
cheaper — to prevent most germ diseases than to suffer 
from them. 
8. Sanitation is sensible. CHAPTER THIRTY-FOUR 
WHAT GOVERNMENTS CAN DO TO PRESERVE THE 
PUBLIC HEALTH 
Just what a government should do to preserve the 
health of its citizens depends on whether the people 
over whom it is watching live in the tropics or in the 
colder portions of the earth, and on whether they are in 
cities and towns or in the country. Yet the principles 
of sanitation are everywhere the same — the government 
must do those things that are necessary to the health of the 
community which the people cannot do for themselves, and 
it must compel every one to live in such a way that he 
will not be dangerous to others. From your study of 
former chapters of this book you will understand many 
of the duties of a government that are connected with 
preserving the health of a people. We will, however, 
point out a few of the more important ways in which a 
government can save its citizens from disease. 
Quarantining in cases of epidemic diseases. One very 
important duty of a government is to quarantine cases of 
epidemic diseases. If you had a handful of weed seeds 
in a cup, you could easily destroy them by throwing them 
into the fire. But if some one should scatter these seeds 
over your garden and lawn, it might be a work of 
months to get rid of the weeds that would grow from 
them. So in epidemic diseases it is easy to quarantine 
a single patient and keep the germs from being spread 
abroad, but it is very difficult to control some of these 
diseases after the germs have been scattered. Some 
physicians, even, do not appreciate the importance of 
this fact, and instance after instance could be given of 
great epidemics of disease that could have been entirely 
prevented if the first cases had been promptly dealt with. 
177 178 
PRIMER OF SANITATION 
Not only may a community injure itself by failure to 
enforce quarantine, but it may injure some other com- 
munity that is far away. The 
man who started the great small- 
pox epidemic in Montreal (page 
124) came from Chicago, and the 
man who caused the typhoid epi- 
demic at Plymouth, Pennsylvania 
(page 88), came from Philadel- 
phia. What we need all over the 
country and all over the world is 
such careful quarantining of in- 
fectious diseases that they will be 
driven from the earth. Both for 
the sake of its own people and 
for the sake of people in other 
places, every community should 
enforce strict quarantine of each 
case of sickness that has the 
appearance of smallpox, yellow 
fever, diphtheria, or other epi- 
demic disease, until it is known 
that the disease is one that is not 
dangerous to the public health. 
Building hospitals and sanatoria. Governments should 
build hospitals to which persons who are suffering with 
severe epidemic diseases can be taken. This not only 
prevents the spread of these diseases, but is best for the 
patients also; for hospital physicians who have made 
a special study of epidemic diseases have the great- 
est skill and experience in treating diseases of this 
kind. 
no quarantine 
quarantine 
Fig. 106. From 1866 to i875i 
when quarantine was not en- 
forced, the average annual 
death rate from scarlet fever in 
Massachusetts was 7.7 for 
every 10,000 inhabitants. From 
1896 to 1905, when quarantine 
was strictly enforced, the aver- 
age annual death rate from 
scarlet fever was 1 for every 
10,000 inhabitants. DUTIES OF GOVERNMENTS 
179 
It is the duty of the government also to provide 
sanatoria where persons who are suffering from long- 
continued cases of in- 
fectious diseases can go. 
There are 500,000 con- 
sumptives in the United 
States, and in all the in- 
stitutions of the country 
there are enough beds, 
pay or free for only a 
small part of these con- 
sumptives. Our country 
has no greater need 
today than sanatoria that will stop the spread of this 
disease and will give its victims the treatment that they 
need. 
Providing a pure water supply. In the country it is 
usually possible for a family that is willing to use a 
reasonable amount of care and intelligence to provide 
itself with a pure water supply. In cities and in larger 
towns where the people are crowded together the soil 
always becomes polluted and well water is impure. It 
then becomes impossible for each family to secure a safe 
water supply, and it is the business of the city to furnish 
a supply of pure water for all the people. If a city fails 
to do this, many of its people will die of intestinal 
diseases. For the experience of the whole world is 
that cities and towns that must depend on shallow wells 
and on streams for their water are greatly scourged 
by intestinal diseases, while cities and towns that 
have pure water are comparatively free from these 
FlG. 107. Governments of cities and towns 
should keep down dust in the streets. 180 
PRIMER OF SANITATION 
Providing a system of sewage disposal. It is abso- 
lutely necessary for any government that wishes to pre- 
serve the health of its citizens to provide some method 
for the disposal of sewage. 
Where there is a water sup- 
ply and a system of sewers, 
the problem is made easy for 
each family. Where there is 
no water and no such system 
of sewers, the government 
should take up the work 
of cleaning out all closets, 
and should provide carts to 
haul the matter in them 
away where it can do no harm. 
It is not enough for the government of a town to 
pass laws requiring that all closets be kept in a sani- 
tary condition, for where families live on small lots the 
only safe way to dispose of the matter in closets is 
to haul it away, and it is a waste of money to require 
each separate family to hire this done when the govern- 
ment can have the same work done at a fraction of the 
cost to the people. In small towns that have no water 
supply the question of sewage disposal is of special im- 
portance. For the sanitary condition of a town is hope- 
less as long as it has neither a water supply nor a system 
of sewage disposal. It might be added that a town 
which provides some way of purifying its sewage before 
running it into a stream to infect the water supply of 
another town, is doing nothing more than to follow the 
Golden Rule. 
Collecting vital statistics. In all the leading countries 
Fig. 108. In a city the govern- 
ment should assist the citizens to 
keep their premises in a sanitary 
condition. DUTIES OF GOVERNMENTS 
181 
of the world except the United States, a record is kept 
of all deaths and the causes of them. In over one 
half of our country, statistics in regard to the number of 
deaths and the diseases that cause them are collected, 
but in the remainder of the country this very important 
duty of the government is neglected. 
Why vital statistics are important. If typhoid fever 
is a common disease in your town, the water supply 
needs to be improved. If a large number of little chil- 
dren are dying from intestinal diseases, the milk supply 
as well as the water supply should be looked after. If 
scarlet fever and diphtheria keep interfering with the 
schools and causing more deaths than they cause in 
other towns, your health officers are not quarantining 
and disinfecting as well as they do in other places,. 
If the death rate from malaria is high, a campaigr 
against mosquitoes should be undertaken. 
How are we to find out whether or not infectious dis- 
eases are more common in a town than they should be ? 
By keeping a record of all cases of these diseases and 
the number of deaths that they cause and comparing 
our figures with the figures from other places. How are 
we to tell which diseases are most important in our com- 
munities ? By keeping a record and comparing the 
number of deaths caused by each. No one can tell 
what diseases are most common in a town without 
vital statistics. No one can tell whether or not sanitary 
measures are improving the health of a town as they 
should unless an account is kept of the number of deaths 
in the town before and after these measures are taken. 
All of us have lived among tuberculosis all our lives, but 
how many of us dreamed that tuberculosis was as im- 182 
PRIMER OF SANITATION 
portant a disease as it is, until the facts were collected 
and set down in cold figures ? “ Let us have facts, real, 
unmistakable facts; for without facts there can be no 
true science.” 
How death rates are calculated. If you should exam- 
ine the report of a health official, you would probably 
find in it death rates for the month or year for the city 
or state as a whole, and death rates for different diseases. 
At first these death rates may seem a little confusing, 
but when we understand how they are calculated they 
are in reality very simple. The death rate of a country 
means the number of deaths in that country for each 1000 
inhabitants. In 1911 the death rate in the United 
States was 14.2 for that part of the country in which 
vital statistics are kept. For the same year it was 14.6 
in England and Wales, 9.3 in New Zealand, 25.1 in 
Hungary, 13.8 in Sweden, 19.6 in France, and 23.2 
in Spain. This means that in each of these countries 
there were as many deaths for each 1000 inhabitants as 
the figures given above show. Name some of these 
countries in which the sanitary conditions are probably 
not good. 
The death rates that are given for different diseases 
mean the number of deaths caused by these diseases for 
each 100,000 of population. In 1910 the death rate from 
typhoid in England and Wales was 5. In the United 
States it was 23.5 (where statistics are kept). This 
means that in England and Wales there were 5 deaths 
from typhoid fever for each 100,000 of population, and 
in the United States there were 23.5 (more than four 
times as many) deaths from typhoid for each 100,000 in- 
habitants. In our country the death rate in 1912 was .3 DUTIES OF GOVERNMENTS 
183 
from smallpox, 9.3 from whooping cough, 18.2 from 
diphtheria and croup, 149.5 from tuberculosis, 11.5 from 
meningitis, and 132.2 from pneumonia. 
Which of these diseases is it most important for us 
to check? Why do you suppose typhoid fever is so 
much more common in the United States than in Eng- 
land ? Look over the table on page 184 and suggest 
sanitary measures that the people of certain places 
ought to put into practice. 
How to study vital statistics. The best way for you 
to begin the study of vital statistics is to examine the 
figures for your own city or town and then compare 
them with figures from other places. Ask your health 
officer for a copy of his last annual report and look for 
the tables showing the cases of infectious diseases and 
the causes of deaths. Make a table showing the number 
of deaths from these diseases and compare them with 
the figures from other places. Then make a list of the 
sanitary measures that you think would most improve 
the health of your town. If your health officer has no 
report of this kind, your town and your state ought to 
pass laws that will make it possible for vital statistics 
to be collected. For a health officer who is compelled 
to do his work without vital statistics is in exactly the 
same position that a merchant would be in if he were 
compelled to run his business without keeping any 
books.1 
Reporting cases of infectious diseases. All cases of 
infectious diseases should be reported to the health offi- 
cials, and they should keep a record of these cases. 
1 In some states very useful reports on vital statistics can be obtained 
from the State Registrar of Vital Statistics at the capital of the state. 184 
PRIMER OF SANITATION' 
General 
Death Rate 
Typhoid Fever 
Malaria 
Smallpox 
Measles 
Scarlet Fever 
Whooping 
Cough 
Diphtheria 
and Croup 
Tuberculosis 
(All Forms) 
Tuberculosis 
of the Lungs 
Meningitis 
Pneumonia 
(All Forms) 
Diarrhea 
and Similar 
Diseases 
(In Children 
under 2 years 
of Age) 
United States: Total 
13-9 
13-3 
3-o 
0.2 
II.I 
3-3 
10.2 
i4-5 
141.6 
123.8 
7-1 
137-3 
65.6 
White 
*3-5 
11.9 
i-7 
0.1 
II.2 
3-4 
9.2 
14.8 
127.I 
110.5 
7.0 
132.0 
64.4 
Colored 
20.5 
33-5 
21.8 
0.4 
9.8 
1.1 
23.8 
9.2 
346.9 
312.7 
8.5 
212.0 
82.0 
Indiana 
13.6 
21-5 
1.4 
7-3 
3-7 
9-3 
13-9 
I36.O 
II5-5 
5-5 
14-3 
62.6 
Kentucky 
12.6 
31-0 
6.4 
0.2 
7-9 
2.4 
13-4 
17.1 
194.4 
1705 
12.1 
110.7 
49-9 
White 
11.6 
29.0 
5-4 
0.2 
8.4 
2- 5 
12.1 
17.7 
163.2 
141-5 
12.3 
101.9 
49.6 
Colored 
21.3 
47-7 
14.9 
4.0 
0.8 
24.2 
12.5 
4634 
420.9 
10.5 
187.0 
52-9 
North Carolina 
l3-1 
29.2 
14.0 
o-5 
7-i 
2.6 
16.7 
17.1 
148.9 
134-9 
9.8 
104.8 
77-9 
White 
11-4 
22.6 
9.2 
0-3 
6.9 
3-5 
IO.7 
20.0 
103-5 
92.0 
9.9 
84.1 
74-5 
Colored 
16.8 
43-8 
24.6 
1.1 
7.6 
°-5 
29.9 
10.6 
248.5 
228.9 
94 
149.9 
85.2 
Pennsylvania 
14.6 
13.6 
0.2 
18.1 
2.8 
12.2 
194 
130.1 
112.3 
8.0 
167.7 
101.7 
Washington 
7-7 
5-i 
0.1 
0.1 
5-5 
0.8 
5-o 
2.4 
81.3 
66.5 
3-5 
534 
11.1 
San Francisco 
15-4 
3-5 
0.9 
i-3 
i-7 
3-9 
28.3 
193.6 
169.4 
4-5 
129.0 
18.1 
Chicago 
14-5 
5-2 
0.2 
5-4 
6.4 
4.0 
3i-5 
150.2 
132.8 
7-5 
158.1 
141.4 
St. Louis 
14.9 
9-4 
1.6 
8.8 
6-3 
9.8 
20.9 
I44.9 
129.0 
6.6 
173-5 
49-9 
New York City 
Your state 
Your city 
13-9 
3-9 
o-3 
9-9 
2.2 
6.9 
18.5 
173-7 
154-9 
5-7 
179.9 
58.1 
The general death rate shows the number of deaths from all causes for each 1000 inhabitants. The death rates for the differ- 
ent diseases show the number of deaths from each of these diseases for each 100,000 inhabitants. Where more than ten per 
cent of the population is colored, the white and the colored death rates are given separately. The figures given are for 1916. 
IN THE UNITED STATES 
*—i 
CO 
W 
H 
<3 
W 
W 
H 
< 
W 
Q DUTIES OF GOVERNMENTS 
185 
Then the officials can know whether children are attend- 
ing school from a house where there is whooping cough 
or measles. They can then make sure that cases of 
scarlet fever and diphtheria are quarantined. They 
can see that the wastes from typhoid patients are 
destroyed, and they can do something to help consump- 
tives and to prevent their spreading the disease. Every 
law providing for vital statistics should require physicians 
to report all cases of infectious disease to health officials 
as early as possible. 
Other duties of the government. A government 
should further guard the health of its citizens by keep- 
ing a watch for germ carriers who may start epidemics, 
by disinfecting houses where consumptives have lived, 
and by vaccinating its citizens against smallpox. It 
should remove or cause to be removed the breeding 
places of flies and mosquitoes, and where there is danger 
of plague, it should wage war against rats. It should 
guard the milk supply, and put in force measures for 
keeping down dust. It should prohibit spitting in pub- 
lic to guard against consumption especially. Dispen- 
saries where consumptives and mothers with siqk babies 
can be advised and assisted are good investments for any 
city or state. It is also the duty of a government to pro- 
vide sanitary school buildings and clean playgrounds for 
its future citizens, and to have medical inspectors keep 
Vital statistics for any part of the United States where they are kept and 
estimated populations for non-census years for states and cities of more 
than 8000 inhabitants may be obtained from the annual reports on Mor- 
tality Statistics, published by the United States Bureau of the Census. 
Your health officer probably has a copy of this book, and he will doubtless 
allow you to copy from it any figures that you may need in your study of 
this subject. 186 
PRIMER OF SANITATION' 
watch over the children in the schools. Above all else 
a government should educate its people in regard to 
preventable diseases. 
Fig. 109. In both city and country the public health nurse is becoming one 
of the most important agents in the prevention of sickness. Day after day 
she moves about among the people, advising them on matters of health. 
POINTS TO BE REMEMBERED 
1. A government should quarantine epidemic diseases. 
2. It should build hospitals and sanatoria where the victims of 
infectious diseases may be cared for. 
3. It should provide a pure water supply for its citizens. 
4. It should provide a system of sewage disposal. 
5. It should collect vital statistics. 
6. It should carry out such other measures as may be neces- 
sary to protect its citizens from preventable disease. CHAPTER THIRTY-FIVE 
PRACTICAL SANITATION 
We have now made a study of the common germ 
diseases and of the sanitary methods that may be em- 
ployed to prevent these diseases. The question now is, 
what can a few people do to improve the sanitary con- 
dition of a community ? All great works take time, and 
to reform a town that is a total stranger to all sanitary 
measures usually requires years of patient effort. By 
intelligent work, however, a community can soon put 
itself in better sanitary condition and begin to cut down 
the number of deaths from infectious diseases in the 
community. 
Educating the public. The chief trouble in carrying 
out sanitary measures is that many people do not under- 
stand anything at all about germ diseases. There are 
in our country many persons who do not yet know that 
malaria is carried by mosquitoes, or that a person who 
is only slightly ill, or not ill at all, may be carrying 
typhoid germs. These persons cannot understand the 
importance of sanitation. Neither do they carry out 
sanitary measures intelligently when they do try to im- 
prove the healthfulness of their surroundings, for it is 
an easy matter to look in the wrong place for germs. 
Every one, therefore, who spreads a knowledge of 
disease germs is helping the sanitary condition of his 
community, for where knowledge of disease germs goes, 
there intelligent and successful efforts to escape from 
them will soon follow. 
Sanitation in cities. A great city can be kept in 
sanitary condition only by the government, and a citi- 
zen can best serve the cause of sanitation in a city by 
187 188 
PRIMER OF SANITATION 
working through the health officials. The good citizen 
should use his powers to have honest, intelligent men 
elected to office, and he should support measures that 
will give these men enough money to have the health 
of the city properly guarded. In every city there are 
candidates for office who seek the support of the people 
by professing to believe in an economical government 
and a reduction of the taxes. In many cases it is possi- 
ble to reduce the taxes only by allowing the schools, the 
police and fire departments, the streets, the parks and 
public playgrounds, and other interests of the city to 
run down, and by turning disease germs loose to work 
their will on the people of the city. The citizen who 
wishes sanitation in his city should therefore, first of 
all, interest himself in the life of the city and see that 
the right men are given control of public affairs, and 
he should advocate sanitary measures and everywhere 
preach the doctrine that public sanitation is not possible 
without expending public money. The citizen can also 
best do his part in the great sanitary work which a 
state and a nation should carry on by upholding faith- 
ful health officials and by reporting any who may be 
lazy or careless about their work. 
Sanitation in villages. From a sanitary point of view, 
the position of many villages and small towns is most 
melancholy. Enough people have collected in them to 
make it impossible for any one family to protect itself 
by its own sanitary efforts, as a family can do in the 
country. Even in a small town there are enough people 
to keep many rain barrels that will breed mosquitoes, 
many manure piles that will hatch flies, many offensive 
closets to threaten the health of the town. Enough peo- PRACTICAL SANITATION 
189 
pie can collect about the post office or the store in the 
smallest village to cover the sidewalk in front of the 
buildings (and sometimes the floors of the buildings 
themselves) with expectorations. At the same time, the 
small town usually has no water supply except wells, 
no system of sewage disposal, and no health officials 
who are paid enough and have authority enough to 
allow them to do much toward preserving the public 
health. 
In these towns and villages much may be done for 
the cause of sanitation by a few intelligent, active work- 
ers. Village improvement associations can be organized 
to study how the town may be made a more healthful 
and pleasant place to live in. These associations can 
help to educate the people in regard to consumption 
and other diseases that are always in the village. They 
can keep before the public the necessity for having clean 
playgrounds for small children. They can encourage 
the people to sod along the sidewalks and to set out trees, 
and this will help in keeping down the dust. They can 
use their influence against spitting on sidewalks and 
can find other ways to assist in keeping the streets clean. 
Above all, they can uphold the physician who is acting 
as health officer when some one in the town becomes 
offended at him, and they can exercise a great influence 
on the officials of the town. If the members of a town 
council know that the intelligent people of the town want 
the breeding places of insects to be removed, the weeds 
in the streets to be cut down, the closets in the town to 
be kept in a sanitary condition, the streets to be sprinkled, 
and at the earliest possible moment a water supply to be 
provided for the town, they will be more likely to look 190 
PRIMER OF SANITATION 
after these things than they will if no one thinks or says 
anything about the health conditions of the town. 
FIGS, no and III. Which of these will permit the people in the house to 
make the more effective fight for sanitation ? 
Freeing the country farmhouse from disease. In the 
country insanitary neighbors are not so great a danger 
as they are in towns and cities, and by intelligent effort 
a family in the country can to a great extent free 
itself from germ diseases. If country families will clear 
away weeds and dense shrubbery from around their 
homes, and look after the breeding places of mosquitoes, 
they can do much to protect themselves against malaria. 
By removing the breeding places of flies, avoiding the 
polluting of the soil about their homes, and guarding 
their milk and water supplies, they can in a great meas- 
ure free themselves from intestinal diseases. Sunlight 
admitted freely to the house is one of the most powerful 
disinfectants known, and the fresh country air admitted 
freely to the sleeping rooms at night will do much to 
build up the body and increase its germicidal power. PRACTICAL SANITATION 
191 
Germ diseases are almost as common in the country as 
in the city, but with a little care a family in the country 
can avoid most of them. 
The necessity of setting a good example. He who 
would be a successful preacher of any doctrine must 
himself be willing to put into practice that which he 
preaches, and he who would help the cause of sanitation 
ttiber- 
culosis 
pneumonia 
diarrhea 
(infants) 
diph- 
the- 
ria 
typhoid 
fever 
whooping 
cough 
small- 
pox 
Fig. 112. In March, 1912, Robeson County, North Carolina, appointed a 
physician to give his whole time to looking after the health of the people. The 
diagram shows the number of deaths from certain diseases, in 1911, the year be- 
fore the health officer began work, and in 1914, after he had been at work three 
years. Fifty-five per cent of the people in the county are colored. 
in his community-must first of all see that his own prem- 
ises are in a clean and sanitary condition. The family 
that keeps a rain barrel to breed mosquitoes need not 
complain if a neighbor keeps a manure pile for the hatch- 
ing of flies; the man who spits on the sidewalk need 
not be surprised if a passing consumptive leaves a swarm 
of tuberculosis germs by his front gate; and the family 
that keeps an offensive closet behind the house is in no 
position to make a successful fight for better sanitation 
in the town. The first and greatest service that we can 
render the cause of sanitation is to cease to offend 
against sanitary laws ourselves; and this will not be 192 
PRIMER OF SANITATION 
without profit to us, for, after all, most families suffei 
from germ diseases more because of 
their own carelessness than because 
of the faults of others. 
Practical results of sanitation. 
Sanitation is nothing new, for several 
thousand years ago the Jews kept 
their lepers under strict quarantine, 
and their laws called for a careful 
disposal of human wastes. By sani- 
tary measures plague, smallpox, chol- 
era, yellow fever, and typhus fever, 
formerly the greatest scourges of 
mankind, have practically been driven 
from the civilized world. By sanita- 
tion other germ diseases are rapidly 
being controlled, and there is hardly 
an infectious disease that can be men- 
tioned that has not been either ban- 
ished or seriously checked in many 
communities. For thousands of years 
sanitation has been tried and proved 
to be a great success, and its advo- 
cates today are only asking that the 
measures that have freed us from our 
worst plagues shall be used to free us 
from the lesser diseases that still afflict 
us. Figures 112 and 114 show what 
has been done in a few years to check 
some of these diseases, and as yet we 
have hardly begun to fight them with the idea of driving 
them from our land. 
Fig. 113. Diagram 
showing the death rate 
from typhoid fever in 
Jacksonville, Florida. 
In 1910 there were 8500 
open closets in the city. 
By 1913 these closets 
had been screened 
against flies. No other 
changes in the sanitary 
condition of the city 
that would affect the 
typhoid death rate were 
made during this time. PRACTICAL SANITATION 
193 
When we can keep the germs that are in the bodies 
of the sick from getting to those that are free from these 
germs, then nearly all cases of germ diseases will disap- 
tuberculosis 
pneumonia 
diarrhea 
{infants) 
diphtheria. 
typhoid 
fever 
Fig. 114. Diagram showing the death rate (number of deaths per 100,000 in- 
habitants) from certain infectious diseases in 1900 and in 1912 in the part of the 
United States where vital statistics are kept. Sanitation is now saving tens of 
thousands of persons from dying of these diseases each year, and our health 
officials know how to save tens of thousands more. 
pear from the earth. That it is possible to do this in 
the great majority of cases, all experience in sanitation 
abundantly proves. 
POINTS TO BE REMEMBERED 
1. Education in regard to germ diseases always helps the 
cause of sanitation. 
2. In cities, states, and nations, citizens can best serve the 
cause of sanitation by supporting the health officials. 
3. Most small towns and villages need sanitary reform. 
4. In these places much can be done for sanitation by edu- 
cating the people and by interesting the local officials. 
5. A country family can largely free itself from germ diseases. 
6. Experience shows that by sanitation most germ diseases can 
be completely banished or at least greatly checked. CHAPTER THIRTY-SIX 
A NEW KIND OF DISEASE GERM 
Bacteria can easily pass through the pores of a brick 
or the pores in the walls of a vessel made of coarse clay, 
but if a liquid containing bacteria be passed through the 
walls of a filter made of the very finest clay, the bacteria 
will be strained out. There are certain diseases, how- 
ever, the germs of which are so small that they pass 
through the finest filters. Some of these germs appear 
as mere points under even a powerful microscope, and 
many of them have not been seen at all. Most of them 
are like protozoa rather than bacteria, but all of them 
are much smaller than any bacteria or protozoa that we 
know and seem different from germs of these kinds. 
They are called filtrable viruses, — “ filtrable ” because 
they pass through a filter, and “ viruses ” because, long 
before the germ theory of disease was understood, 
physicians called that which passes from one person to 
another in an infectious disease the virus of the disease. 
About forty diseases are now known to be caused by 
germs of this kind. One of them (mosaic disease of 
tobacco) is a plant disease. Many of them are animal 
diseases, hog cholera being the most important of these 
in our country. Among the human diseases that belong 
in this class are measles, smallpox, rabies, yellow fever, 
dengue fever, and infantile paralysis. The germs of 
scarlet fever, typhus fever, and trachoma probably are 
also of this kind, although there is some doubt about 
their passing through filters. We have already studied 
some of the best known of these diseases. Others with 
which we are less familiar we shall discuss at this 
time. 
194 A NEW KIND OF DISEASE GERM 
195 
INFANTILE PARALYSIS (POLIOMYELITIS) 
Infantile paralysis was first described in 1881, and 
since that time it has been found in nearly all parts of 
the world. It seems to be becoming much more wide- 
spread year by year, especially in the United States. 
Its onset is sudden and severe, the spinal cord and brain 
being especially affected, and it often leaves the patient 
with some part of the body paralyzed. It attacks chil- 
dren under five years of age especially, but older per- 
sons also may suffer from it. The germs are found in 
the secretions from the nose and throat, and in the 
wastes from the alimentary canal. 
The germ of infantile paralysis. Under a microscope 
the germ of infantile paralysis appears like a very small 
coccus, but it is much smaller than any known bacte- 
rium, — only about one fourth the diameter of one of 
the pus-forming cocci. It can withstand considerable 
drying, and can cause the disease in monkeys and rab- 
bits as well as in man. 
How the disease is contracted. Our present knowledge 
indicates that the germs of infantile paralysis are spread 
in the secretions of the nose and mouth. It has been 
proved that many healthy persons who are in contact 
with cases of the disease become carriers of the germs 
and spread the disease. To control infantile paralysis 
it is therefore necessary to quarantine not only the 
patients but also those who have been in contact with 
them. In 1916 a great epidemic of 9023 cases occurred 
in New York City. The history of this epidemic shows 
that vigorous measures are required to control the 
disease. 196 
PRIMER OF SANITATION 
LETHARGIC ENCEPHALITIS 
This disease of the brain is sometimes called the 
“ sleeping sickness ” because the patient lies for long 
periods as if asleep. The germ is thought to be a 
filterable virus. Probably it enters and leaves the body 
through the mouth and nose. 
TYPHUS FEVER 
Typhus fever is a very severe disease that was for- 
merly known as ship fever, or jail fever, and was not 
clearly distinguished from typhoid fever. It has gradu- 
ally disappeared from the United States, and except for 
occasional cases in the crowded parts of our cities, in 
our seaports, or on the Mexican border, it is no longer 
found among us. It is still common in the higher 
regions of Mexico and in other parts of the world. 
The germ of typhus fever has not been discovered,1 
but it is known that it is in the blood, and that the dis- 
ease is spread by the bite of the louse, especially the 
body louse. The method of preventing the disease is 
to destroy the vermin that carry the germs. 
ROCKY MOUNTAIN FEVER 
This disease is especially prevalent in the Bitter Root 
Valley, Montana, but it is found also in Wyoming, Idaho, 
Washington, and other western states. The germ is 
carried by ticks, and the disease is contracted from the 
bite of an infected tick. How the germs get into the 
tick is not known, but some of the ticks found in nature 
are carrying them. The method of preventing the dis- 
1 It has recently been reported that typhus fever is caused by a bacillus 
that grows in the blood. A NEW KIND OF DISEASE GERM 
197 
ease is to avoid the bites of ticks and to destroy the 
ricks. Methods of freeing land from these pests by 
grazing with sheep1 and by destroying the ticks that 
attach themselves to other domestic animals are rapidly 
being worked out. 
TRACHOMA (GRANULATED LIDS) 
Trachoma is a disease of the eyes that has been found 
to be very widespread in our country.2 Many cases, es- 
pecially in the early stages, appear to be mild, but some 
cases are very severe, and blindness is sometimes caused 
by it. It is a stubborn disease to cure, but it can be 
made to yield to proper medical treatment. 
The germ of trachoma. Some investigators believe 
that trachoma is caused by the same germ that causes 
pink eye (page 97), — that it is a chronic form of pink 
eye in which the germs continue to grow in the eyes for 
years, forming little ulcers and scars (granules) in the 
linings of the lids and in the eyeball. The more com- 
monly accepted idea is that it is caused by an undis- 
covered filtrable virus. The germs are in the secretions 
from the eyes, and trachoma is an infectious disease. 
Preventing the spread of trachoma. The germs of 
trachoma doubtless get into the eyes from wash basins 
1 Ticks die unless they can attach themselves to an animal, and if a 
flock of sheep are allowed to graze over tick-infested territory, most of 
the ticks will attach themselves to the sheep. The oil on the wool of the 
sheep then coats over the small breathing pores of the tick, and 90 per 
cent of the ticks will be killed. Cattle, horses, and hogs are freed from ticks 
by spraying them with an insect-killing liquid, or by driving them through 
vats filled with a liquid of this kind. 
2 In some parts of the country, as many as twenty school children in a 
thousand have been found to be suffering with trachoma. 198 
PRIMER OF SANITATION 
and towels, from the hands, and in other ways. The 
disease spreads through families and through schools, 
and a trachoma patient needs to take great care to 
guard the eyes of others from the germs. Any one 
whose eyes continue red or painful should have them 
examined at once by an oculist or a physician, and if 
he has trachoma, both for his own sake and for the 
sake of those about him, he should have his eyes treated. 
Until the patient is cured, he should not be allowed to 
attend school or other public gatherings where he may 
spread the disease. 
FOOT-AND-MOUTH DISEASE 
Foot-and-mouth disease attacks cattle especially, but 
swine, sheep, goats, and other domestic animals, as well 
as man, may suffer from it. The disease gets its name 
from the fact that in cattle infected with it, blisters and 
sores appear in the mouth and on the delicate skin be- 
tween and above the hoofs. It is very infectious, and 
in Europe it has given great trouble. In the United 
States it has been kept under better control, but in the 
winter of 1914-1915 a great outbreak occurred. It is 
caused by a filtrable virus, and the germs are in the 
milk, saliva, and other secretions, as well as in the sores. 
They remain alive for months if kept cool and moist, 
but die when they are dried. The effective methods of 
controlling the disease consist of preventing the ship- 
ment of cattle from infected areas, killing all cattle in 
infected herds, and Pasteurizing milk to prevent the 
disease in man. It is so infectious that it never remains 
hidden, and by using sufficiently energetic measures it 
is possible to keep it under control. A NEW KIND OF DISEASE GERM 
199 
FOWL TUMOR 
Another animal disease that is caused by a filtrable 
virus is a kind of tumor in chickens. This disease has 
attracted much attention, because in it the cells multiply 
and grow in an unnatural manner, as they do in tumors 
and cancer in man. A small tumor that grows on the 
skin of the face in man is also known to be due to a 
virus of this kind, and some physicians have long believed 
that cancer is infectious and will finally prove to be a 
germ disease. It is most important to discover the cause 
of this disease ; for’ cancer and tumors in our country are 
now causing nearly 75,000 deaths each year and they 
have increased greatly (probably 25 per cent) since 1900. 
Warts have recently been reported as being due to a 
filterable virus. It has long been believed that one per- 
son can catch them from another. 
1. Some disease germs pass through the finest filters. 
2. Measles, smallpox, rabies, yellow fever, and other common 
diseases are due to germs of this kind. 
3. The germs of infantile paralysis are in the secretions from 
the mouth and nose and in the body wastes. 
4. Cases of this disease should be carefully quarantined. 
5. Typhus fever is contracted from the bite of the louse. 
6. Rocky Mountain fever is contracted from the bite of a tick. 
7. Cases of trachoma should be treated and quarantined. 
8. Foot-and-mouth disease is a very infectious disease of cattle, 
which man may contract from milk. 
9. Cancer may prove to be a germ disease. 
POINTS TO BE REMEMBERED CHAPTER THIRTY-SEVEN 
NEW DISCOVERIES IN REGARD TO GERM DISEASES 
It is now only about forty years since the germ theory 
of disease came to be understood, and it is wonderful 
that we should have learned so much about these dis- 
eases in so short a time. Our knowledge of them is 
still incomplete, however, and scientists are constantly 
studying them and the germs that cause them, and 
each year new discoveries in sanitation are being made. 
Many of these discoveries prove most valuable in the 
warfare against germs, and each year we learn better 
how to bring communicable diseases under control. In 
this chapter we shall study some important facts in pre- 
ventive medicine that have been discovered in the last 
few years. 
A study of tuberculosis. In 1913 in Minnesota, forty 
city families, in each of which a consumptive had been 
living for a year or more, were investigated. In every 
one of these families it was found that at least one other 
person was infected, and in ten of the families every 
member was infected. All together, there were in these 
forty families 207 persons living with consumptives, 
and of these 207 persons, 138 had contracted the dis- 
ease. At the same time, fifteen families in which 
there were no consumptives were investigated, and in 
these families only two persons out of eighty were found 
to be infected. Other studies in the rural parts of 
Minnesota seemed to show that parts of counties where 
no consumptives had lived were entirely free from the 
disease, and that where it had been introduced into a 
community, it had spread to the families living on the 
farms close to the consumptives. It was also concluded 
200 NEW DISCOVERIES IN GERM DISEASES 
201 
from these studies that the danger of infection depends 
on the amount of exposure to the germs; that the 
danger from a chance meeting with a consumptive, or 
from living in the house with him for a few days, is not 
great, but that there is great danger of infection if one 
lives with a consumptive for a long period of time and 
is exposed to great numbers of the germs day after 
day (page 151). This study indicates that isolating 
cases of tuberculosis is the most important measure in 
preventing the spread of tuberculosis, and in Minnesota 
a consumptive is required either to reside in a sanatorium 
or to live separate from the other members of the family 
in the home. 
Contact infection. This study, like all the newer in- 
vestigations of the subject, leads us to believe that it is 
not from air, dust, clothes, or furniture that germs 
usually reach us, but that they are passed in a rather 
direct way from one person to another on the hands, or 
on drinking cups, dishes, and other articles. This pass- 
ing of germs from one person to another in large num- 
bers and without giving them an opportunity to dry is 
called contact infection, and undoubtedly the great ma- 
jority of cases of diseases like typhoid fever, pneumonia, 
influenza, diphtheria, whooping cough, scarlet fever, 
measles, and tuberculosis, originate in this way. So 
important indeed do some health officers now consider 
this method of infection, and so few cases of many dis- 
eases do they think come from houses, furniture, and 
clothes, that they have given up the disinfecting of 
houses after cases of diphtheria, measles, and scarlet 
fever, and are spending their energies in finding and 
isolating the persons who are carrying the germs. 202 
PRIMER OF SANITATION 
The theory on which this practice is based is that when 
mucus and other matter containing germs is dried on 
desks, doorknobs, or other articles, the great majority of 
the germs die at once; that the others are weakened by 
the drying; and that the small number of weakened 
germs that one would get from articles of this kind is 
not dangerous like the great numbers of fresh germs 
that one may receive direct from the patient himself, or 
from something he has just handled. 
Two aids in preventing contact infection. One of the 
most effective measures for preventing contact infec- 
tion is medical inspection of 
schools, because where this is 
practised cases of infectious 
diseases are found in their 
early stages and removed be- 
fore the germs spread to oth- 
ers.1 Another great aid in 
preventing contact infection is 
hospitals for isolating cases of 
typhoid fever, pneumonia, in- 
fluenza, diphtheria, and other 
like diseases. These hospi- 
tals can give patients suffering 
with such diseases better care, 
better nursing, and better 
medical attention than they 
receive in their homes; they can at once cut off much 
sickness by stopping the spread of these diseases through 
Fio. 115. By medical inspection 
in schools, early cases of infectious 
diseases are discovered. 
1 One French sanitarian, in referring to the custom of disinfecting 
schoolrooms to stop the spread of measles, exclaimed : “ The germs are in 
the nostrils of the children, and they disinfect the furniture! ” NEW DISCOVERIES IN GERM DISEASES 
203 
families; and they ought to be established in every 
county and town in the land. 
A safe disposal of human wastes. Notwithstanding 
all the campaigns for sanitation that have been carried 
on in recent years, there are hundreds of thousands of 
farms in our land that are still without closets, and in 
villages, school grounds, church yards, and beside coun- 
try homes, there are hundreds of thousands of open 
closets still in use. Any one who knows the habits 
of the housefly — how day after day it passes back 
and forth between these places and dining-rooms and 
kitchens — knows that as long as such a condition con- 
tinues, not even a beginning in sanitation and hardly a 
beginning in civilization has been made. It cannot be 
too strongly insisted upon that one of the first and most 
important of all sanitary measures is to provide a safe 
means of disposing of human wastes, and a sanitary 
toilet arrangement should be a part of every human 
habitation in the land.1 
Screening against mosquitoes. The ordinary screens 
that are placed on houses are fly screens, and not mos- 
quito screens, and the meshes in them are so coarse that 
the mosquitoes that carry malaria and yellow fever can 
pass through them. To keep the malaria mosquito out 
1 Complete directions for building sanitary closets may be obtained 
from any State Board of Health, or from the United States Public 
Health Service, Washington, D.C. The International Health Board 
suggests that ff nothing better can be provided, a box placed in the 
forest or among bushes may be turned, mouth down, over a small pit 
and moved from time to time. The box can be made fly-tight by banking 
the earth around it and covering the openings, and this is the most im- 
portant point in the construction of a closet. When the box is moved, 
the pit should be filled with earth. It is not safe to use wastes from a 
closet as a fertilizer for gardens. 204 
PRIMER OF SANITATION 
of a house requires a screen with about sixteen strands 
to the inch, and to turn the yellow fever mosquito, 
twenty wires to the inch are necessary. Galvanized or 
bronze screens will in the end prove cheaper than 
painted iron wire, and they permit the air to pass 
through them much more freely. Careful work is 
needed to make the screening on a house effective; for 
a feeding of blood is necessary to the female mosquito 
before she can lay her eggs, and she will search over 
screens until she finds the smallest crack or opening, or 
even come down chimneys, to get into a house. Since 
mosquitoes are attracted by light, lamps should be kept 
away from doors in the evening, and on a screened porch 
the lights should be placed at the other end from the 
door. It has been reported that ducks are most valu- 
able in destroying the larvae of mosquitoes, and that if 
ponds are kept free from the large fish that feed on 
minnows, the minnows will allow almost no mosquitoes 
to breed in the water. 
Bad after-effects of infectious diseases. Recently an in- 
vestigation has been made by the Metropolitan Life 
Insurance Company of New York, of the death rate 
among 1574 of its policy holders who suffered from 
attacks of typhoid fever in 1911. Of these 1574 per- 
sons, 146 died of the disease, and 1428 survived; but 
during the next three years fifty-four of these survivors 
died ">f other diseases, twenty-one of them of tuber- 
culosis. This gave a death rate more than twice as 
high as was to be expected among persons of this age.1 
1 It is estimated that in the United States 178,200 persons survived 
attacks of typhoid fever in 1914, but that 7781 of these survivors will die 
inside of three years, because of the damage done them by the disease. NEW DISCOVERIES IN GERM DISEASES 
205 
In the same way, bad after-effects follow measles, diph- 
theria, scarlet fever, influenza, pneumonia, and other 
germ diseases, and to take no account of these after- 
effects is like leaving out of account the wounded when 
one is reckoning the losses in war. 
Raising the defenses of the body by vaccination. In 
the last few years the idea of preventing by vaccination 
certain diseases that are not well controlled by sanita- 
tion has gained great headway. Not only is this prac- 
tised for the prevention of smallpox, rabies, and certain 
animal diseases, but vaccination against typhoid fever 
has now been proved to be a great success.1 The 
same methods have been employed to check epi- 
demics of cholera, plague, meningitis, and whooping 
cough; and some individuals have themselves vac- 
cinated against colds, influenza, pneumonia, and other 
diseases.2 The theory of all vaccination is the same, 
— weak or dead germs are introduced into the body, 
and this causes the germ-killing power of the body to 
be increased. 
The prevention of plague. Plague is first of all a dis- 
ease of rodents (animals like rats, mice, squirrels, prairie 
dogs, and rabbits), and the only way of fighting it is to 
fight the rats that are the principal carriers of it. Some- 
thing can be done by trapping and poisoning them, but 
1 Formerly typhoid fever was the most dreaded of all camp diseases, 
and usually during war more soldiers died from it than from wounds. 
During the spring of 1911 the United States had a force of 15,000 sol- 
diers, all vaccinated against typhoid fever, in camps in Texas, and only 
one case of the disease appeared among them. 
2 It is reported from Russia that epidemics of scarlet fever have been 
checked by vaccination against the pus-forming bacteria (streptococci) 
that are always present in this disease. 206 
PRIMER OF SANITATION 
they multiply so rapidly that the only effective way of 
dealing with them is to cut off their food supply and 
break up their homes.1 To do this it is necessary to 
keep garbage in covered cans ; to rat-proof slaughter 
houses, mills, warehouses, and stores ; to provide cement 
floors and rat-proof bins in livery stables and barns; 
and either to close rats out from under buildings and 
floors or to raise these enough for dogs and cats to pass 
freely under them. Houses should be built so that rats 
cannot get into cellars or walls, 
and all wharves should be rat- 
proof because of the danger 
of plague-infected rats landing 
from a vessel at any time. A 
campaign against rats is expen- 
sive, but it is more expensive to 
support an army of rats than it 
is to drive them out, even were there no question of 
health concerned. 
Hookworm in dogs. It is reported that the disease 
called “ black tongue ” in dogs is caused by hookworms 
and that the infection among both dogs and cats is wide- 
spread. The hookworms that attack animals are differ- 
ent from those that infect human beings, but in general 
it is coming to be believed that we contract disease from 
animals more frequently than was formerly supposed, and 
that dogs and cats are not good companions for children. 
Fig. 116. The cheapest and 
most effective kind of rat trap. 
1 There are often ten or twelve rats in a litter, and a female white rat 
has been known to give birth to more than eighty young in a year. It is 
estimated that there are more rats than men sailing the seas; that in cities 
there are as many rats as people; and that in the country there is one rat 
to each acre of land. In California, plague spread from the rats to the 
ground squirrels in the country and has not yet been eradicated. NEW DISCOVERIES IN GERM DISEASES 
207 
Controlling epidemics of measles in schools. Because 
the first symptoms of measles resemble a cold and the 
disease is often not recognized in its early stages; be- 
cause it is highly infectious in these first stages ; because 
cases of the disease are so mild that they are over- 
looked ; because the germs are so powerful that they can 
successfully attack almost every one they can reach; 
and because its victims are chiefly small children,1 
measles is a most difficult disease to control. One use- 
ful plan in schools is as follows: When a pupil is 
attacked, the school is continued as usual for about 
eight days. Then the children who were exposed to the 
disease are kept out of school for a week. After this, all 
those who have not developed the disease or are not 
being exposed to it at home are allowed to return (page 
132). 
A disease that has been confused with tuberculosis. 
Recent investigations prove that a number of cases of 
supposed tuberculosis are not due to the tubercle bacil- 
lus, but to a threadlike fungus (Nocardia). It is not 
known how common this disease is, but it requires differ- 
ent treatment from tuberculosis, and it is important that 
it be distinguished from tuberculosis. 
Infectious jaundice. This is a communicable disease 
in which the patient becomes yellow in color. Occa- 
sional cases and sometimes local epidemics of it occur in 
our country, and it proved troublesome in the trenches 
1 Diseases that attack small children do not receive the same attention 
as diseases that attack prominent citizens in the midst of their careers. 
The prevention of measles has, therefore, been neglected, and we have in 
our country during some years more than 1,000,000 cases with more than 
10,000 deaths. 208 
PRIMER OF SANITATION 
during the recent war. The germ lives in both man and 
the rat and leaves the body in the discharges from the 
kidneys and the bowels. It can be transferred from one 
person to another as typhoid germs are transferred, or 
the disease can be contracted from foodstuffs that have 
Fig. 117. Isolation hospital for cases of infectious diseases at Jacksonville, 
Florida. To prevent the spreading of germs within the hospital, the water 
faucets and doors are arranged so that they may be opened with the elbows. 
The windows are covered with full-length screens to keep out flies and mosqui- 
toes, but there is no fear that the germs will travel through the air and visitors 
are allowed to talk to patients through the windows. 
been infected by rats. Many wild rats carry the germs, 
and it is dangerous to allow food to be soiled by them. 
Varieties of the pneumonia germ. Recent investiga- 
tions indicate that there are four races, or types, of the 
pneumonia germ. Three of the races are very danger- 
ous and are commonly found only in the bodies of 
pneumonia patients or in the mouths of persons who 
are taking care of these patients. Germs of these three 
races cause nearly 80 per cent of all cases of pneumonia 
and more than 90 per cent of all deaths from the disease. 
These virulent types of germs, like the diphtheria 
germ, may remain in the mouths of patients for a NEW DISCOVERIES IN GERM DISEASES 
209 
long time (twelve to ninety days) after the onset of the 
disease. 
The fourth race of pneumonia germs is less dangerous 
than the others. It is found in the mouths of about 
60 per cent of healthy persons, and if for any reason the 
defenses of the body are lowered, it may invade the 
lungs. About 20 per cent of pneumonia cases are due 
to this type of germ, but usually the attack is mild, and 
only about 6 per cent of the cases end in death. 
Pellagra. Certain investigations made in recent years 
indicate that pellagra spreads only where the sanitary 
conditions are bad; that when villages are sewered and 
the precautions taken that prevent typhoid fever, new 
cases of pellagra do not develop. From this it has been 
inferred that it is caused by an undiscovered germ that 
is in the intestinal wastes, and that the disease can be 
prevented as intestinal diseases are prevented, — by 
pure water, pure milk, and a safe disposal of the body 
wastes. 
On the other hand, there is much reason for believing 
that pellagra is due to a lack of proper food. In two 
orphan asylums, in which there were many cases, the 
sanitary conditions were left unchanged but a more 
liberal supply of milk, eggs, peas, beans, and oatmeal 
was provided in the diet. The previous year there had 
been seventy-nine cases of pellagra in one of the asy. 
lums and one hundred and thirty cases in the other. 
The year following the change in diet, barring recent 
admissions, there were no cases of the disease in one 
institution and only one case in the other. Because of 
facts like these some authorities have held that pellagra 
is a diet disease, and that it may be prevented by a 210 
PRIMER OF SANITATION 
more abundant and more varied supply of food. Fresh 
meats, eggs, milk, peas, beans, whole grains, and fresh 
vegetables are foods that seem to protect against pel- 
lagra. Living on salt meats, canned goods, fine flour or 
fine corn meal, molasses, and foods cooked with soda is 
held to cause the disease. (See pages 354 and 356.) 
Perhaps the explanation of these seemingly conflicting 
facts is that pellagra is a germ disease, but that a proper 
food supply raises the resistance of the body to the 
germs. Further investigations are necessary before a 
final decision in regard to the matter can be made. 
1. Recent studies indicate that most cases of tuberculosis 
come from living with consumptives. 
2. Contact infection is supposed to be the principal method 
of spreading germs. 
3. Hospitals and medical inspection of schools aid greatly in 
preventing contact infection. 
4. Sanitary toilet arrangements should be a part of every 
human habitation. 
5. Fine screens are required to keep out mosquitoes. 
6. Many persons die because of the after-effects of infectious 
diseases. 
7. The defenses of the body against many germs may be raised 
by vaccination. 
8. Plague can be controlled only by fighting rats. 
9. Some supposed cases of tuberculosis are due to fungi and 
yeasts. 
10. A disease of the teeth is caused by an ameba. 
11. There are several distinct races of the pneumonia germ. 
POINTS TO BE REMEMBERED PART II 
PRIMER OF PHYSIOLOGY CHAPTER ONE 
THE POSSIBILITIES OF GOOD HEALTH 
Fig. i. The length of time a top will spin depends on the conditions under 
which the spinning is done. 
Three boys at the same time threw their tops into a 
ring drawn on the earth. One top struck a pebble, 
bounded into the air, and fell motionless on its side. 
Another top worked its way into a little sandy hollow 
in the earth, and in thirty seconds its spinning was over. 
The third top settled down on the smooth earth and 
continued to spin steadily and quietly for more than a 
minute. 
How long will a top spin ? It is not possible to answer 
this question definitely because the length of time it will 
spin depends on the conditions under which the spinning 
is done. 
Length of human life dependent on the care that is 
given the body. In Europe three hundred years ago, 
the average human life was twenty years; today it is 
213 214 
PRIMER OF PHYSIOLOGY 
forty years. At the present time it is in India twenty- 
four years and in Sweden fifty-two years. In New York 
City twelve years have been added to the average life 
since 1866, and in Indiana from 1900 to 1910 human 
life lengthened at the rate of six months each year. 
During this period, therefore, 
the people of Indiana may 
be said to have won back 
one-half the time that the 
passage of the years took 
from them. 
There is a common idea that 
the body has a certain “ nat- 
ural ” lifetime. The facts 
show that this idea is incor- 
rect. The engine of an auto- 
mobile wears out in a mo*ith 
if it is neglected, and it lasts 
for years if it is given proper 
care. The human machine 
likewise has no definite length 
of life. It may be destroyed 
in its first month by impure 
milk; it may suddenly be 
wrecked by the germs of 
typhoid fever after it has been running smoothly for 
twenty-five years; or, if properly cared for, it may give 
good service for sixty, seventy, or even eighty years. A 
top spins longer on a smooth than on a rough surface; 
an automobile lasts longer when it is given proper care 
than when it receives rough treatment; and human life 
is longer when the body lives and works under favor- 
Sweden 
Massachusetts 
Europe 
India 
52 yi»s. 45 yrs. 40 yrs. 24 yrs. 
Fig. 2. A diagram showing the 
average length of life in different 
parts of the world. The length of 
time the human body lasts depends 
on the care that it receives. THE POSSIBILITIES OF GOOD HEALTH 
215 
able conditions than it is when the body is neglected 
and abused. 
The possibilities of preventing sickness. In India, 
where the people live under bad sanitary conditions, 
there is a daily average of 
eighty-four sick persons for 
each one thousand of popula- 
tion. In Spain, for each one 
thousand inhabitants the daily 
average is fifty-six; in the 
United States it is thirty; and 
in New Zealand it is nineteen. 
In five of the largest Euro- 
pean cities, in the year 
1880, the daily average of sick 
persons was fifty-five for each 
one thousand inhabitants; by 
1909 this average had fallen 
to thirty-one. In the United 
States there is still much pre- 
ventable illness, but the sick- 
ness among us decreased 23 
per cent between the years 
1890 and 1909. 
These facts prove that the 
amount of sickness in differ- 
ent countries depends on the 
degree of intelligence that the 
people use in dealing with matters of health. They show 
that each community has it largely in its own power to 
decide how many of its people shall each day be sick 
and how many of them shall be in health. 
India 
Spain 
United States 
New 
Zealand 
Fig. 3. A diagram showing the 
average daily number of sick per- 
sons per 1000 inhabitants in dif- 
ferent countries. The amount of 
sickness in any country depends 
to a great extent on the degree of 
intelligence its people use in deal- 
ing with matters of health. 216 
PRIMER OF PHYSIOLOGY 
Disease prevails because of ignorance. In our own 
country there are at all times 1,500,000 persons seriously 
ill with preventable diseases. This means that each 
year we have 1,500,000 years of unnecessary sickness 
among us. Why do people undergo all this suffering if 
it is possible to escape it ? It is because there still lin- 
gers in the common 
mind the age-old idea 
that disease is an unes- 
capable thing sent upon 
us by the Fates, ’and 
that health comes be- 
cause of good fortune 
and not because it is 
deserved or earned. 
We now know that 
this belief is incorrect; 
that if men are willing 
to work for health and 
to earn it, they may, in 
the great majority of 
cases, have it. Within 
the last forty years the 
real causes of most dis- 
eases have been dis- 
covered; the methods 
of preventing them have been worked out. Some of 
these discoveries we are taking advantage of, but many 
of them are not understood by the people, and as yet 
there is not a community in the world that will allow 
its health officers and physicians to use all their knowl- 
edge in the prevention of disease. The ancient Greeks 
FIG 4. A diagram showing the number of 
typhoid fever cases in Williamsburg, Virginia, 
from 1906 to 1913. In 1911 the closets were 
screened, so that flies could not carry typhoid 
germs about the town. THE POSSIBILITIES OF GOOD HEALTH 
217 
taught that knowledge is virtue and ignorance is sin. 
The great sin in the hygienic world today is ignorance, 
and we are punished for this ignorance by the prevent- 
able illness that is among us. 
Learning to keep the laws of life. Cut your finger and 
you will suffer; burn your hand and you will smart for it. 
Observe the laws under which your body lives and you 
Figs. 5 and 6. Louis Cornaro and Alexander the Great. Alexander, a daring 
and all-conquering warrior of the ancient world, died at the age of 33 because 
he paid no attention to his health. Cornaro, who was an Italian nobleman, 
lived from 1464 to 1566—102 years. When he was 40 years old he was told by 
his physicians that he would die, but he gave great attention to hygiene, regained 
his health, and lived to enjoy a life of profit to himself and others. 
will enjoy health; break them and you must bear the 
punishment. Whether you like these laws or not has 
nothing to do with the question. You did not make 
them; you cannot change them. All that you can do is 
to find out what they are and then obey them. As you go 
through life, you will doubtless find certain persons who 
do not wish to recognize the existence of these laws and 
who are trying to find some means of escaping from 
them. This is’impossible ; for Nature’s decrees are un- 
yielding and unchangeable. The sensible course, there- 218 
PRIMER OF PHYSIOLOGY 
fore, is to listen to the commands of Nature, to learn her 
laws and give obedience to them. In this book we shall 
study the human body and the laws of its life. 
QUESTIONS 
What was the average length of life in Europe 300 years 
ago? What is the average length of life at the present time 
in India? in Sweden? In New York City how much has been 
added to the average life since 1866 ? How rapidly was life 
lengthened in Indiana from 1900 to 1910 ? Is there a “ nat- 
ural ” lifetime for the body? Give a reason for your answer. 
How many persons are sick each day for each 1000 inhabitants 
in India? in Spain? in the United States? in New Zealand? 
How much has sickness decreased in certain European 
cities during the last 30 years? in the United States during 
the last 20 years? How much preventable illness is there in 
the United States each year? Why do people allow this 
sickness among them? What result follows the keeping of 
Nature’s laws? What is the result of breaking these laws ? 
What course should we pursue with regard to them ? 
SUGGESTIONS TO THE TEACHER 
Keep before the class at all times the idea that health is the nor- 
mal condition of the body and that disease is in the main prevent- 
able. Make the pupils realize that health conservation has ceased to 
be a scientific problem and has become a social and educational prob- 
lem ; that science has pointed out how to save annually in the 
United States 600,000 lives and how to prevent most of the sickness 
from which we suffer. 
Secure from local city and state boards of health whatever vital 
statistics are available and point out the great number of deaths 
occurring locally from preventable diseases. For suggestions as to 
additional material that may be used with this chapter, see page 227. CHAPTER TWO 
THE HUMAN BODY AND THE CELLS OF WHICH IT IS BUILT 
Have you ever watched a little plant push its way 
out of a seed, thrust its roots downward into the earth, 
and unfold its leaves to the light ? And have you seen 
such a plant grow larger day by day, until finally it blos- 
somed and bore seeds like the parent seed from which 
it grew ? If you 
have worked in a 
garden and un- 
derstand plants, 
you must often 
have thought that 
they are very 
much like the 
people about us in 
the way they grow 
and go through 
the cycle of their lives. This is indeed the truth, 
and, in order that you may better understand your 
own bodies, we shall begin this chapter by learning 
something of the structure of a plant and of how a 
plant grows. 
A plant composed of cells. If you could examine 
a small portion of a leaf or other living part of 
a plant under a microscope, you would find that it 
is composed of little parts built together, as stones 
are built together to make a wall. The little parts 
of which the plant is built are called cells. Each 
cell is composed of a half-liquid living material, 
which is inclosed by a cell wall. In the center of 
the living matter is a denser portion, which is called 
Fig. 7. The life cycle of the bean. 
219 220 
PRIMER OF PHYSIOLOGY 
the nucleus. All the living parts of a plant are com* 
posed of cells. 
How the young plant starts from a cell called the egg. 
Break open a seed and you will find in it a young plant. 
Where did it come from ? It grew from a cell called 
the egg. This cell at first is like the other cells of 
which the seed is built, but at a certain time it increases 
Fig. 8, Cells from the liver, as 
seen under a microscope, highly 
magnified. 
Fig. 9. Cells drawn diagrammat- 
ically to show the spaces among 
them, highly magnified. 
in size and gathers to itself a rich food supply. It then 
begins to divide, and from it the new plant comes. Be- 
fore we begin the story of its growth, however, there are 
some other things that it is well for us to understand. 
The parts of a flower. Examine almost any common 
flower, and you will have no trouble in recognizing the 
parts shown in Figure n. First come 
the little green sepals, then the bright- 
colored petals, next the stamens, and in 
the center one or more pistils. The 
lower part of the pistil contains the young 
seeds and becomes the seed pod. In the 
heads of the stamens is a fine, powdery 
substance called pollen. When we ex- 
amine pollen under a microscope, we see that it is 
composed of a great number of little grains. Each 
Fig. io. A pine 
seed cut open to 
show the young 
plant in it. THE HUMAN BODY AND ITS CELLS 
221 
little grain is, in reality, a cell; each contains living 
matter and a nucleus, as do other cells. 
The egg fertilized by the pollen. Bees visit flowers 
for the nectar that is in the blossoms and for the pollen, 
which they gather and 
mix with honey in mak- 
ing “ bee bread ” for 
their young. In pass- 
ing into a flower and 
out of it, a bee often 
leaves pollen on the 
sticky outer end of the 
pistil. When a pollen 
grain is thus left on a 
pistil, a long, thread- 
like tube grows out 
from it, makes its way down through the pistil to a young 
seed, enters the seed, and finds the egg (Fig. 13). 
Then a nucleus from the pollen grain passes out of the 
tube and unites with the nucleus of 
the egg. The uniting of the nucleus 
of the pollen grain with the nucleus 
of the egg is called fertilization, and 
the egg is said to be fertilized, be- 
cause in some way it is given the 
power to grow and make a new plant.1 
The growth of the egg into a new plant. After the 
egg is fertilized, it begins to grow. In a very short time 
stamen 
petal 
pistil 
sepal 
Fig. ii. The parts of a flower. To the 
left is a pistil cut open to show the location 
of the young seeds. 
Fig. 12. Pollen grains. 
On the left a pollen tube 
is shown growing out 
from the grain. 
1 When the pollen is washed away by rains, or when the spring is so 
cold and wet that bees and other insects cannot visit the flowers, the straw- 
berry, plum, peach, and cherry crops fail. Without the pollen the eggs in 
the young seeds do not grow, the seeds die, and the fruit drops off. 222 
PRIMER OF PHYSIOLOGY 
it divides into two cells. Each of these again divides, 
making four cells, and the process goes on until there 
is a group of many cells, which 
have come from the dividing of 
the egg. From these cells are 
formed the roots, the stem, the 
leaves, and the other parts of the 
new plant. The outer ones change 
into skin or bark to protect the 
delicate living cells within. Some 
change into long wooden vessels 
to carry water from the earth up 
to the leaves; some form vessels 
for carrying food throughout the 
plant; and other cells take up 
all the different kinds of work 
that must be done within the 
plant. Usually the little plant 
stops at a certain stage of growth and rests within 
the seed until the warmth of the next spring stirs 
the cells into renewed activity and calls the plant 
forth to a new life. 
pollen 
grain 
pollen 
egg 
Fig. 13. Diagram show- 
ing how the pollen tube 
passes down through the 
pistil to the egg. 
Fig. 14. Four stages in the development of the young plant from the egg. A 
represents the egg, B shows the division into two cells, and C and D are later 
stages. In two of the cells in C, the nuclei have divided, but the new cell walls 
have not yet been formed. THE HUMAN BODY AND ITS CELLS 
223 
The growth of the human body from a single cell. 
The human body, like the body of a plant, starts from 
one cell. This cell divides and re-divides until it forms 
a great cluster of thousands of cells. Of these cells 
all the organs and parts of the body are built. Some 
cells build lime around themselves and form the bones. 
Some build a great network 
of tough fibers, called con- 
nective tissue fibers, which 
hold all the body together. 
Other cells make up the 
muscles; certain cells form 
organs for digesting the 
food; the outermost ones 
make for the body a tough 
covering which we call the* 
skin; a great group in the 
head and along the back 
become the brain and nerv- 
ous system ; and still other 
cells become fitted for doing 
all the other kinds of work 
that must be done in the 
body. Thus we see that 
the human body, like the bodies of all living things, 
whether they be plants or animals, starts with a single 
cell; and that when the body is grown, all its parts are 
composed of cells, or of supporting substances, like bone 
or connective tissue fibers, that the cells have built. 
The cells alive. You will now understand that if you 
could examine with a microscope a small portion of the 
heart, the liver, or the brain, you would find it com- 
Figs, is and 16. In its first stage 
connective tissue is a group of cells 
which build around themselves a mass 
of jelly-like material, as shown in Fig. 
15. This material hardens into the 
fibers that are seen between the cells 
in Fig. 16. All through the body a 
framework of connective tissue runs, 
holding the cells, organs, and tissues 
in place. 224 
PRIMER OF PHYSIOLOGY 
posed of a multitude of small cells. You will under- 
stand also that each of the four hundred thousand 
million cells that are estimated to be in the human 
body is alive; that each must have food and oxygen 
and all the things that the body as a whole needs; 
that the life of the body is the sum of the life of all 
its cells. When we study how to keep the body in 
health, therefore, we are only study- 
ing how to keep the cells in health ; 
for health means that the cells are 
in good condition, and sickness 
means that there is trouble among 
the delicate little parts of which the 
body is built. 
The cells bathed by lymph. We 
have said that the cells of the body 
are built together as stones are built 
into a wall. You would not, how- 
ever, have a correct idea of the 
structure of the body if you did not 
understand that all among our cells 
there are spaces and openings, and that these crevices 
are filled with a liquid which escapes from the blood. 
This liquid is called the lymph, and the cells are sur- 
rounded by it and bathed in it, as a fish is bathed in the 
water in which it swims. Only to a very limited extent 
is it true that we are dry-land animals; for the living 
parts of our bodies spend their lives under water as 
truly as do the fishes of the sea. 
Pure lymph necessary to the health of the cells. If 
you had hundreds of small fish in a pail of water, you 
would be compelled to take great care in keeping the 
FIGS. 17 and 18. On the 
right is shown a nerve cell 
from the brain; on the 
left, a muscle cell from 
the stomach. THE HUMAN BODY AND ITS CELLS 
225 
water fresh and in feeding them, lest they should die, 
So with the cells crowded together as they are in oui 
bodies, it is necessary to keep the lymph pure and clean 
and to supply it with the food and oxygen that the cells 
need. We therefore have a stomach and other organs 
for preparing food for the cells; we have lungs for 
taking in oxygen and for breathing out the waste car- 
Fig. 19. As clean water is necessary for the health of the fish, so is pure 
lymph necessary for the health of the cells. 
bon dioxid; we have kidneys for taking other poison- 
ous wastes out of the body; and we have many other 
organs, each of which does its part in keeping the 
lymph rich and pure for the cells. When these organs 
do their work, our cells are like fishes living in pure, 
clean water where there is an abundance of food, and 
we are strong and well. If any organ fails in its work, 
either the cells will lack something that they need or 
the lymph in which they live will become impure, and 
the body will fall ill. Pure and rich lymph is necessary 
for the health of the cells. 226 
PRIMER OF PHYSIOLOGY 
Keeping the human machine in repair. From what 
you have now learned, you will understand that your 
body is a machine of many parts. You will understand 
also that you are in charge of this machine, and that 
the length of time it will last and the amount of time it 
will be laid up for repairs depend on the care that you 
give it. In this book we shall study how the body is 
built and how it works ; for no one can care intelligently 
for a machine that he does not understand. 
QUESTIONS 
Of what is a plant composed? Describe a cell. Where 
does the young plant within a seed come from? Name the 
parts of a flower. What is pollen ? Why do bees visit flowers ? 
What do they do for flowers? What grows from the pollen 
grain when it is placed on the pistil? What is fertilization? 
Describe the growth of the egg. 
From what does the human body start? Of what are all the 
organs of the body built? Name some of the different kinds 
of cells and tissues in the body. 
What do the cells of the body need in order that they may 
live? What is meant by health? by sickness? What fills the 
crevices among the cells? What is lymph? What kind of 
lymph is necessary to keep the cells in health ? What organs 
prepare food for the cells? What organs take in oxygen? 
What organs give off wastes ? What happens if any of these 
organs fail in their work ? 
SUGGESTIONS TO THE TEACHER 
If possible, secure a compound microscope and allow the pupils to 
examine cells. Cells scraped from the inside of the cheek or lip, 
or the living skin from an inner layer of an onion, may be used in 
demonstrating cell structure. Prepared longitudinal sections of a 
growing root or stem tip show not only the cells, but their differentia- THE HUMAN BODY AND ITS CELLS 
227 
tion into tissues. Make clear the point that bone, cartilage, and 
connective tissue are built by the cell depositing dead materials about 
themselves, and that the living cells constitute only a small part of 
these supporting tissues. 
Identify parts in a simple flower; demonstrate pollen under a 
microscope. The pollen grains may be made to germinate by 
placing them in a solution of sugar and water (a 5 per cent to 40 
per cent solution, according to the kind of pollen used). Have the 
pupils plant sunflower seeds in pots. Select two equally vigorous 
plants; give one plenty of light and water, and set the other in a 
dark corner of the room and allow the soil to become dry. Note 
the difference in the appearance of the plants and call attention to the 
fact that the human body, like plants, is dependent on environment. 
Statistics show that for each death in a community there are on 
an average about two years of sickness. From local vital statistics 
have the pupils compute how many years of sickness are annually ex- 
perienced by the people of your city and state. 
The economic loss from preventable disease is estimated at $16 
per year for each inhabitant of the United States; compute the 
yearly loss to your city and state from this cause. Borrow compound 
interest tables from a bank and have members of the class find what 
sum the average American citizen would have to his credit at 20 and 
60 years of age if this waste could be stopped and the money in- 
vested at 5 per cent compound interest. CHAPTER THREE 
THE FRAMEWORK OF THE BODY 
Any one looking at the solid walls of a tall building 
would naturally suppose that these walls carried the 
weight of the great structure above them. As a matter 
Of fact, the building has a steel framework which sup- 
ports it and braces it in time of storm, 
and the walls do not bear even their 
own weight. This is shown by the 
fact that the workmen often finish 
a portion of the wall many stories 
above the ground, before they build 
in the parts that connect it with the 
earth. The important thing in sup- 
porting the building, therefore, is 
the hidden framework which out- 
lines the shape of the building and 
carries its weight; it is not the 
walls, which are a mere covering 
hanging on the framework. 
The skeleton. The human body, 
like a great building, has a frame- 
work which gives the body its shape 
and provides support for it. This 
framework is composed of 206 bones. All the bones 
taken together are called the skeleton. 
In addition to supporting the body, the bones protect 
delicate organs like the brain and heart, and make it 
possible for the muscles to move the different body 
parts. Feel your wrists, your sides, your cheeks, or 
almost any part of your body, and you will find the 
bones under the skin and soft flesh. We shall now 
Fig. 20. The weight of 
the building is carried by 
the steel framework. 
228 THE FRAMEWORK OF THE BODY 
229 
cranium 
skull 
- clavicle 
sternum 
- humerus 
’ulna 
spinal 
column 
radius 
pelvic bone 
carpal bones 
sacrum 
coccyx 
metacar pals 
phalanges 
.femur 
patella 
tibia 
fibula 
tarsal bones 
metatarsals 
phalanges 
Fig. 21. The skeleton. 230 
PRIMER OF PHYSIOLOGY 
study the more important bones of the skeleton and 
the way in which these bones are joined to make a 
framework for the body as a whole. 
The spinal column the center 
of the skeleton. The backbone, 
or spinal column, is the center 
around which the whole skeleton 
is built. Not only does it run up 
the back and stiffen and support 
the trunk, but it also carries the 
head on its top, and it has the 
bones of the chest and the bones 
of the hips attached to it. It is 
composed of many short bones, — 
an arrangement which gives it a 
great number of joints and enables 
it to bend freely and easily in any 
direction. Each bone of the 
spinal column is called a vertebra 
(plural, vertebrce). Five of the 
lower vertebrae are joined to make 
one large, solid bone which is 
called the sacrum. Below the 
sacrum there are three or four 
small vertebrae which form a little 
tail-like structure, the coccyx, on 
the end of the spinal column. 
The skull. The skeleton of the 
head, or skull, is composed of the 
fourteen bones of the face and of eight bones which make 
a strong box (the cranium) to protect the brain. In the 
skull of a little baby there are places where the bones 
Fig. 22. The skeleton of the 
head and trunk. THE FRAMEWORK OF THE BODY 
231 
have not completely covered the brain. A baby’s head, 
therefore, needs to be protected carefully from blows. 
The ribs and sternum. The ribs are twelve pairs of 
slender bones which curve around the chest and protect 
the heart and lungs. At the back they are attached to 
the spinal column. In front, the seven upper pairs are 
joined to the breast-bone, or sternum, and the next three 
pairs are hung from the ribs above. The two lower pairs 
have their front ends free, and are called floating ribs. 
The bones of the shoulder. The shoulder has two 
bones, — the collar-bone, or clavicle, and the shoulder 
blade, or scapula. The scapula is a flat bone which lies 
on the back of the shoulder. It is fastened to the spinal 
column and ribs, and at its outer end has a socket for 
the head of the arm bone. The clavicle has its inner 
end attached to the sternum; its outer end is propped 
against the point of the scapula, which it supports. 
When the clavicle is broken, as by a fall, the shoulder 
drops forward and downward. 
The pelvis. The pelvic or hip bones are two large, 
widespreading, flat bones that can easily be felt in the 
sides. They are firmly joined to the sacrum at the back 
and to each other in front. .With the sacrum, these 
bones form the bowl-shaped pelvis, which gives support 
to the organs that lie in the lower part of the cavity of 
the abdomen and also furnishes a solid framework to 
which the legs are attached. 
The bones of the limbs. Each limb has in it thirty 
bones, and the bones of the arm and leg are very 
similar. The thigh has in it a great bone called the 
femur, and the arm has in it a corresponding bone called 
the humerus. In the leg below the knee there are two 232 
PRIMER OF PHYSIOLOGY 
long bones, the tibia and the fibula, and in the forearm 
there are two similar bones, the ulna and the radius. 
In the wrist we find a group of small 
bones (the carpal bones), and in the 
ankle is another group of small bones 
(the tarsal bones). In the hand are 
five bones (metacarpals), each bear- 
ing a finger, and in the foot are five 
bones (metatarsals), each bearing a 
toe. Finally, the fingers of each 
hand have in them fourteen bones 
(phalanges), and the toes have the 
same number of bones arranged in 
the same way. The arms and legs 
are built on the same general plan, 
but the wrist has one more bone 
than the ankle, and the elbow has no bone correspond- 
ing to the kneecap {patella) on the front of the knee. 
Bones composed of animal and mineral matter. A bone 
is composed of animal matter and mineral matter. The 
mineral matter is lime. The animal matter consists chiefly 
of tough fibers buried in the mineral groundwork of the 
bone. The animal matter gives the bone its toughness 
and keeps it from breaking. The mineral matter stiffens 
it and makes it able to bear the weight of the body. 
These statements you can prove for yourself by burn- 
ing one bone in the fire and soaking another in a weak 
acid. The first bone has the animal matter burned 
out of it and becomes brittle like chalk. The mineral 
matter is eaten out of the other bone by the acid, and 
the bone becomes limber like a piece of rubber tubing. 
You can easily imagine the difficulties you would be 
Fig. 23. From an X-ray- 
photograph of a broken 
forearm and a wrist. The 
crosses show where the 
bones are broken. THE FRAMEWORK OF THE BODY 
233 
in if your skeleton lacked either the mineral matter 
which stiffens it or the animal matter which toughens it. 
Joints. Close your hand 
and watch your fingers as 
they bend. The bending is 
not in the bones themselves, 
but at the joints between the 
bones, and the advantage 
of having a jointed skeleton 
is that it makes movement 
possible. There are two 
principal kinds of joints in 
the body, — ball-and-socket 
joints and hinge joints. The 
former allow motion freely 
in any direction; the latter 
allow motion only in two op- 
posite directions, as does a hinge. Good examples of ball- 
and-socket joints are found in the shoulder and the hip ; of 
hinge joints at the elbow, at the knee, and in the fingers. 
Cartilage and ligaments. The 
ends of the bones at the joints are 
covered with a smooth, white material 
called cartilage, which is kept moist 
by an oil that is secreted in the 
joints. This keeps down friction 
in the joints. Around the joints 
are many strong bands and cords 
of connective tissue called liga- 
ments. Their chief function is to 
tie the bones together, but they 
also inclose the joints so that the oil cannot escape. 
Figs. 24 and 25. On the left is 
shown the shoulder joint, an exam- 
ple of a ball-and-socket joint. On 
the right is the elbow joint, an ex- 
ample of a hinge joint. 
FlG. 26. The ligaments 
of the wrist. 234 
PRIMER OF PHYSIOLOGY 
The treatment of sprains. When a joint is bent too 
far, the ligaments about it are either torn loose from the 
bones or broken. An injury of this kind is called a 
sprain, and a bad sprain is often more serious than a 
broken bone. The best way to prevent a sprained 
joint from becoming swollen and painful is to bathe it 
in hot water and to massage it, rubbing and stroking it 
in the right direction to send the blood and lymph back 
up the limb to the heart. Driving the lymph on in this 
way will lessen the sweiiing; it will take the pressure 
off the nerve endings and so help to relieve the pain; it 
will carry away the parts that die because of the break- 
ing and tearing of the ligaments; and the fresh blood 
and lymph will bring a supply of oxygen and food that 
will hasten the building up of new ligaments. 
There is a widespread idea that a sprained joint heals 
most rapidly when it is given complete rest, but many 
who are skilled in treating sprains and dislocations 
insist that, if the joint can be properly supported, the 
injured member should be used as soon as possible, 
even when movement causes pain. The reason given 
for this treatment is that exercise helps to keep up a 
good circulation through the part and also lessens the 
danger of the new ligaments being formed so short 
that the joint will be left stiff after the injured tissues 
have healed. 
Dislocations. When a bone is thrown out of place, it 
is said to be dislocated. A few persons have joints so 
loosely tied together that a dislocation is possible with 
little or no injury to the ligaments, but usually in a case 
of dislocation the ligaments are badly torn and broken. 
In such a case, no one but a physician should be allowed THE FRAMEWORK OF THE BODY 
235 
to try to put the bones back in place; for an unskilled 
person may cause much pain and do great damage by 
pulling and twisting at an injured limb. 
Broken bones. When an arm or a leg is broken, it 
should be kept stretched out straight so that the sharp, 
broken ends of the bone will not cut the muscles, nerves, 
and blood vessels 
of the limb. If 
the person must 
be moved, wrap 
a pillow, coat, or 
blanket about the 
injured member, 
using sticks or 
something else 
stiff enough to keep it from bending, as shown in Figure 
27. An injured person may be carried in a blanket, but 
a door, a cot, or other solid support is better. In lifting 
the person, take the greatest care to keep the injured 
limb from bending sharply at the break. 
The two parts of a fractured bone are cemented sol- 
idly together by a jelly-like white substance which ap- 
pears on the broken ends and hardens. If the broken 
ends are not brought together, the fracture cannot heal; 
and if the injured part is not properly bandaged, there 
is always great danger that the bone will be crooked or 
deformed after it has healed. 
The skeletons of old persons and of children. The 
bones of old persons have very little of the living animal 
matter in them. They therefore break easily, and be- 
cause they contain little living matter, a fracture in an 
old person heals very slowly or refuses to heal at all. 
Fig. 27. A broken limb bandaged for moving the 
patient. 236 
PRIMER OF PHYSIOLOGY 
Old persons, therefore, should be saved as much as pos- 
sible from climbing stairs and from doing other things 
that may cause them to fall. 
In little children, on the other hand, there is a small 
quantity of the mineral matter in the skeleton, and the 
bones can easily be bent into almost any shape. Dur- 
ing the growing years, large amounts of lime are needed 
for building and hardening the skeleton, and in most cases 
of defects and deformities of the skeleton, the trouble 
is caused by a lack of proper building materials or of 
other necessary substances in the food (pages 352, 353). 
Importance of caring for the skeleton in youth. Heavy 
lifting will cause the shoulders of a child to droop for- 
ward, making him round-shouldered; making children 
sit with the feet hanging over the edge of a seat will 
cause the legs to be bowed; tight clothing may bend 
in the ribs and cramp the organs within the body; 
habitually sitting or standing in a stooped position will 
cause the skeleton to harden in an incorrect shape ; and 
many persons have the face and head slightly one-sided 
because when they were babies they were allowed to lie 
on one side more than on the other. The skeleton 
should have especial care in youth ; for after the bones 
have hardened, it is difficult to change their shape. 
QUESTIONS 
Give three functions of the skeleton. Of how many bones 
is the skeleton composed? What is the function of the spinal 
column? What is one of the bones of the spinal column 
called ? What is the sacrum, and of what is it composed ? the 
coccyx? How many bones are in the skull? What is the 
cranium ? Why should a baby’s head be protected from blows ? THE FRAMEWORK OF THE BODY 
237 
How many ribs are there in the body ? What is their use ? 
How are they attached at the back? in front? Name and de- 
scribe the two bones of the shoulder. Describe the hip bones. 
To what are they attached at the back? in front? How many 
bones are there in each limb? Name the bones of the arm. 
Name the bones of the leg. 
Of what is a bone composed? What is the use of the animal 
matter? of the mineral matter? How can this be proved? 
Name the two principal kinds of joints in the skeleton. 
Explain the kinds of movements they allow and give examples 
of them. What is cartilage? How is friction in the joints 
prevented? Give two functions of ligaments. 
What is a sprain ? What treatment should be given a sprain ? 
Why? Why should a sprained joint be exercised? What is a 
dislocation ? Why should a broken arm or leg be kept from 
bending? How can this be done while moving an injured 
person? How does a broken bone heal? Why do the bones 
of old persons break easily and heal with difficulty? Why are 
the bones of little children easily bent? What mineral should 
be abundantly supplied in the diet of a child? Name six 
things that may cause the skeleton of a child to take an 
incorrect shape. 
SUGGESTIONS TO THE TEACHER 
Show the supporting skeleton of a leaf, using either an old leaf 
from which the softer tissues have fallen away, or one that has been 
skeletonized by boiling it in a io per cent potassium hydroxid 
(KOH) solution and gently scraping away the soft tissues. 
Use the dry bones of animals in teaching the skeleton ; decalcify 
the drumstick of a chicken, or any other slender bone, by soaking it 
in water to which acid (hydrochloric, sulfuric, or nitric) has been 
added. Such a bone, as well as a skeletonized leaf, may be preserved 
in alcohol or in a 50 per cent aqueous solution of glycerin. CHAPTER FOUR 
THE MUSCLES AND THE CARRIAGE OF THE BODY 
It is a law of physics that a body at rest will remain 
at rest forever, unless some force sets it in motion by 
pushing or pulling on it. For ex- 
ample, it is the pulling and pushing 
of the hand that sends a thrown 
ball upward into the air. It is the 
pull of the earth that brings the 
ball down. It is the push of the 
gases that come from the explosion 
of the powder that sends the pro- 
jectile from a great gun. It is the 
pressure of the steam in the cylin- 
ders of an engine that sets the ma- 
chinery in motion and gives it the 
power to do work. Everywhere 
about us we see objects set in mo- 
tion, and in every case this is done 
by a push or a pull from an outside 
source. 
You can lift your arms; you can 
extend your legs; you can move 
your whole body from place to 
place. Something must be push- 
ing or pulling the different parts 
of the body to cause these move- 
ments. What is it that does this 
work ? It is the muscles that are 
stretched upon the framework of the body. There 
are more than five hundred of these muscles, and they 
make up two fifths of the body weight. You are famil- 
Fig. 28. The muscles. 
238 MUSCLES AND THE CARRIAGE OF THE BODY 
239 
iar with the lean meat in the body of an animal, and as 
this is muscle, you already know something of the appear- 
ance and texture of this “ master tissue” of the body. 
The structure of a muscle. A muscle is composed of 
long, slender, fiber-like cells, which have the power of 
contracting, or shortening and thickening themselves. 
This action of the muscle fibers may be illustrated by 
allowing a stretched rubber band to come back to its 
natural condition; or you can get an idea of how the 
muscle cells change their shape by watching an earth- 
worm shorten and thicken its body as it crawls. 
The long, slender cells lie lengthwise in a muscle, 
and among them is a great network of connective tissue 
fibers, which ties the whole muscle together and attaches 
it to the skeleton. When the muscle fibers contract, they 
cause the whole muscle to shorten and thicken, as you 
can feel by laying your hand on your upper arm while 
the muscle draws itself together and lifts the forearm. 
How the muscles move the different parts of the body. 
The muscles stretch across the joints of the skeleton, 
and when a muscle con- 
tracts, it pulls the bones 
together and causes a 
bending at the joint. 
Exactly how this is done 
you can best understand 
by a study of Figure 29. 
Tendons. In many 
parts of the body long 
cords of connective tissue 
called tendons attach the muscles to bones that are at 
a distance from them. This plan of placing muscles 
Fig. 29. Showing how the muscles of 
the arm lift the forearm. 240 
PRIMER OF PHYSIOLOGY 
at a distance from the parts that they move, keeps mem- 
bers like the hand from being covered with large muscles, 
which would be in the way when delicate work is to be 
done; at the same time it gives these members great 
strength and enables them to make many different move- 
ments. 
How the muscles move the body as a whole. You can- 
not stand on a ladder and pull the ladder up after you. 
tendons 
muscle 
Fig. 30. The muscles of the forearm and the tendons that move the fingers. 
You cannot sit on a chair and lift it. Yet you can move 
your whole body by muscles that are a part of your 
body. This is possible because you have a jointed skele- 
ton that allows you to thrust out parts of the body and 
push against outside objects. How this is done you can 
best understand through an experiment. Stand close 
to the wall, place your hands against the wall, and 
straighten out your arms. This pushes you away from 
the wall and moves your whole body. 
It is by this same method of pushing against some- 
thing that all the different kinds of locomotion in the 
animal kingdom are brought about. The fish, in swim- 
ming, pushes itself forward by striking its tail and fins 
against the water. The bird, in flying, forces itself 
onward and upward by beating against the air with its MUSCLES AND THE CARR I AGE OF THE BODY 
241 
wings. In walking and running, we drive ourselves 
forward by pushing with the feet against the ground. 
The muscles that support the body. Not only do the 
muscles move the body, but they support it when it is 
held erect. Muscles on the front and 
the back of the neck keep the head 
balanced on top of the spinal column. 
When we stand upright, other mus- 
cles hold the skeleton from bending 
at the ankles, knees, and hips, and at 
the joints of the spinal column. The 
most powerful muscles of the whole 
body are those of the back, which lie 
both in front of the spinal column 
and behind it. They are so impor- 
tant in the carriage of the body, that 
we shall study them in some detail. 
Muscles that support the head. The 
head is held from drooping forward 
by muscles which rise from the verte- 
brae of the trunk, from the ribs, and 
from the bones of the shoulder; they 
are attached to the bones of the neck 
and to the back of the skull. The 
action of these muscles can be illus- 
trated by attaching a string to the first 
joint of the finger, as is shown in 
Figure 32. Other muscles on the 
front of the neck keep the head from 
being drawn too far backward. 
The muscles that support the trunk. The trunk is 
kept erect by muscles along the back of the spinal 
Fig. 31. The muscles 
that lie along the back 
of the spinal column. 242 
rRIMER OF PHYSIOLOGY 
column, by heavy muscles that brace the spinal column 
in front in the region of the waist, and by muscles in 
the walls of the abdomen. The action of these muscles 
we shall now take up separately. 
The muscles along the back of the spinal column rise 
from the sacrum and pelvic bones and run up the back 
as high as the base of the neck (Fig. 31). Their func- 
tion is to keep the trunk from falling forward. Their 
action may be illustrated by attach- 
ing a cord to the finger and drawing 
it down the back of the hand, as is 
shown in Figure 32. 
The abdominal muscles are 
stretched between the pelvic bones 
and the ribs and sternum. When 
they contract, they draw the trunk 
forward and cause it to stoop, and 
they keep the body from being 
drawn over backward by the 
muscles of the back. By examin- 
ing Figures 21 and 22, you will 
see how these muscles are at- 
tached and you will readily under- 
stand how they work in opposi- 
tion to the muscles of the back. 
The pull of the muscles along the back causes a 
forward curve in the spinal column at the waist. The 
spinal column is therefore supported in front in this 
region by strong muscles that brace it against the back 
muscles and keep it from bending too far forward. The 
lower ends of these muscles are attached to the femurs, 
which they lift in walking and running (Fig. 33). 
FlG. 32. Illustrating the 
attachment and action of the 
muscles that support the 
head and trunk. MUSCLES AND THE CARRIAGE OF THE BODY 
243 
The body balanced over the feet in standing. If, in stand- 
ing or walking, part of the body is too far forward or back- 
ward, some other part must be thrust out in the opposite 
direction to keep the balance over the feet. If the head 
droops forward, the spinal column between the shoulders 
will sink backward in a balancing curve. The same effect 
is produced by the shoulders fall- 
ing forward so that the weight of 
the arms pulls forward instead of 
downward at the sides. If the back 
bends inward at the waist, thrust- 
ing the abdomen forward, the up- 
per part of the body will be bent 
backward, throwing the chest up 
in front. Each part must be held 
in correct position, for one part out 
of position is sure to force other 
parts out of position also. The 
following rules may be helpful in 
keeping the body in correct posi- 
tion in standing and walking : 
“ Stand tally thrusting up the 
top of the head as high as possible. 
Walk as if you were hung by 
the top of your head. 
Hold the chin close to the neck. 
Press the back of the neck against 
the collar button. 
Keep the abdomen in. 
If the upper part of the body leans too far backward, 
so that the heels pound in walking, sway the body for- 
ward at the ankles until the chest is over the toes. 
Fig. 33. View from the 
front of one of the muscles 
that keep the spinal column 
from bending too far forward 
at the waist. 244 
PRIMER OF PHYSIOLOGY 
In walking turn the toes in. 
Health and vigor are most important in acquiring a 
correct carriage, for if the muscles that hold the body 
upright lie weak and slack on the skeleton, they must 
all the time be forced to do the work that they ought to 
do naturally and without effort 
Mistakes made in trying to secure an erect carriage. 
When the head droops forward, 
the mistake is often made of 
trying to bring it to an upright 
position by pulling the shoulders 
back. The true remedy is to 
tighten the muscles along the 
back of the neck and bring to 
an upright position the upper 
part of the spinal column, on 
which the head rests. 
Another mistake commonly 
made is to throw the head and 
chest back, and at the same time 
allow the back to be bent in 
at the waist and the abdomen 
to be thrust forward. In this 
case, again, the remedy is to 
straighten the curve in the spinal 
column. The muscles that lie 
along the front of the spinal column in the abdominal 
region are attached by their lower ends to the bones of 
the thighs, and one of the exercises that is practiced in 
strengthening them is to lie flat on the back and draw 
the legs up toward the body. Walking, running, and 
hill climbing also exercise and strengthen these muscles. 
Fig. 34. The vertical line pos- 
ture test. {After chart supplied 
by courtesy of American Posture 
League.) MUSCLES AND THE CARRIAGE OF THE BODY 
245 
A third mistake often made is to try to bring the 
shoulders back by throwing the entire upper part of the 
body backward. The shoulders should be drawn back 
without moving any other part of the body, by pulling 
the scapulas flat down on the back. 
The vertical line test of posture. One test of posture 
FIGS. 35, 36, 37. The figure in the center shows correct posture; the head, 
neck, and trunk form one continuous vertical line. On the left, the head is too 
far forward, which causes the spinal column to bend backward between the 
shoulders and forward at the waist. On the right, the shoulders have been 
drawn up, the back bent inward at the waist, and the whole upper part of the 
body thrown too far backward. In the figures on the left and right the head, 
neck, and trunk form a zigzag line. (After chart supplied by courtesy of Ameri- 
can Posture League.) 
that is in use in many schools is called the vertical line 
test. If a vertical line is dropped from in front of the 
ear to the forward part of the foot,1 the long axis of 
1 By forward part of the foot is meant any point from the ball of the 
foot back to the middle of the arch. The place where the line falls on 
the foot varies somewhat in different persons. 246 
PRIMER OF PHYSIOLOGY 
the head, neck, and trunk will, in correct standing 
position, be parallel to it (Fig. 34). If the position is 
incorrect, the line through the axis of the body will be 
zigzag and not a straight vertical line. The test can be 
made by holding a pole in the upright position, as is 
shown in Figure 34. The vertical line should pass just 
in front of the knee and in front of the shoulder. 
When the trunk, head, and neck are held upright, a 
vertical line drawn through the middle of the tip of the 
shoulder should pass through the ear or behind the ear. 
If this line passes in front of the ear, the shoulder is too 
far forward. 
The foot and the carriage of the body. Of the first 
million drafted men who appeared at our army canton- 
ments in the World War, more than 175,000 had flat 
feet, and in 1917 more men were 
discharged from the service for 
flat feet than for any other cause, 
except pulmonary tuberculosis. 
Since deformed of painful feet 
make a good carriage of the body 
impossible, and since most foot 
troubles are due to shoes, we 
shall take up in this chapter the 
question of how the foot carries 
the body weight, and of fitting 
the foot with a correctly shaped 
shoe. 
The structure of the foot. The 
skeleton of the foot is composed 
of 26 bones which are held to- 
gether by muscles and ligaments. 
Fig. 38. The United States 
Army shoe. Improper shoes 
cause so much foot trouble 
that one United States Army 
surgeon has suggested that as 
a measure of military pre- 
paredness all shoes should be 
manufactured over lasts ap- 
proved by the government. 
It is especially important 
that the feet of children be 
not deformed. MUSCLES AND THE CARR I AGE OF THE BODY 
247 
Figs. 39, 40, and 41. From X-ray photographs taken during investigations 
made by the United States Army. Figure 39 shows a foot in a shoe supposed to 
follow the lines of the foot, and commonly regarded as sensible. Note how 
the bones of the third and fourth toes are curled under, and how the great toe 
is bent in toward the other toes. Figure 40 shows the unshod foot of a soldier 
standing on one leg and bearing his 40-pound marching equipment. Note 
how the foot expands and lengthens under pressure. Figure 41 shows a foot 
in the United States Army shoe (Fig. 38). Note the free play of the toes. 
Lengthwise from the heel to the ball of the foot, the 
bones are built together in the form of an arch. There 
is also a cross arch in the foot behind the toes, similar 
to the arch in the knuckles of a closed hand. In walk- 
ing, the foot is moved through tendons that run down 
along the ankle from the muscles below the knee and 
are attached to the bones of the foot. The foot is also 
to a considerable extent supported and held from tipping 
over sidewise by the pull of these tendons from the mus- 
cles of the leg. 
Shoes that interfere with the work of the foot. The 
weight of the foot falls on the heel, on the great toe 
and the ball of the foot behind the great toe, and along 
the outside of the foot behind the little toe. The foot 
is, therefore, a tripod, and if anything interferes with 248 
PRIMER OF PHYSIOLOGY 
any one of its three points of support, it becomes 
very unsteady. 
Figs. 42 and 43. Showing the arch of the foot, and how a high-heeled shoe 
props it up on end. 
A high-heeled shoe props the arch of the foot up on 
end, instead of allowing it to stand in its natural position. 
Shoes with heels that slant forward move the back 
point of support from the heel toward the middle of 
the foot and make walking very insecure and difficult. 
Shoes with pointed toes bend the great toe outward and 
interfere with the inner front point of support, causing 
the wearer to turn the toes out and tending to cause the 
arch of the foot to be turned over on its inner edge.1 
Tight shoes interfere with the outer point of support of 
the foot by keeping the bones back of the toes from 
springing down and spreading apart in a natural mariner 
and thus throwing part of the weight on the outside of 
the foot. All this causes tired and painful feet, and 
makes walking difficult and fatiguing. 
1 In the heel, the point of support is toward the outside, and the inner 
side of the ankle is in a great measure held up by tendons from the muscles 
in the calf of the leg. If for any reason the muscles of the leg are weak, 
the inner side of the ankle is not sufficiently supported by them and the 
arch of the foot is allowed to turn over on the inside. A wide, low heel 
built forward and out under the inner side of the ankle supports the foot 
at this weak point. MUSCLES AND THE CARRIAGE OF THE BODY 
249 
The points of a good shoe. A good shoe should have 
a wide, low heel, or for a natural foot, no heel at all. It 
should be straight along the inside so that it will not 
bend the great toe around toward the other toes. It 
should be long enough not to cramp the toes, and it 
should have a box in it high enough not to press on the 
toes and cause corns and ingrowing nails. The sole 
should be flat across, only slightly turned up at the toe, 
and wide enough that the outer border of the foot will 
not overhang it. 
It is especially important that shoes be roomy enough 
to permit the feet to spread and the toes to move in 
walking; for if these movements are not allowed, the 
muscles of the feet will not develop and will lack the 
strength necessary to support the arches under the body 
weight. 
The position of the foot in standing and walking. In 
walking, the feet should be carried pointing straight for- 
ward ; for when the toes are turned outward, there is a 
tendency for the arch of the foot to be turned over so 
that it lies on its inner side. In standing, the toes may 
be turned outward somewhat, but only to a moderate 
degree. A person who “ toes out ” should practice turn- 
ing his toes inward as he walks. This position of the 
foot is very important in securing a correct carriage of 
the body. 
QUESTIONS 
How many muscles are there in the body ? What part of 
the body weight is muscle ? 
Describe the cells of a muscle. What is the function of 
the connective tissue in a muscle ? How does a muscle cause 
the skeleton to bend at a joint ? What is a tendon ? Of what 250 
PRIMER OF PHYSIOLOGY 
advantage is it to have tendons in the body ? Explain how 
the muscles move the body in walking and in running. 
What function have the muscles in addition to that of mov- 
ing the body? What muscles support the head? Describe 
the three sets of muscles that support the trunk. 
What happens if in standing or walking any part of the 
body is too far backward or forward ? Give seven rules that 
may help in securing a good carriage of the body. Why is 
health important in securing a good carriage ? Explain three 
mistakes that are commonly made in trying to hold the body 
erect. Explain how exercising the legs keeps the spinal 
column from bending too far forward at the waist. Explain 
the vertical line test of posture. Is your own posture correct 
by this test? What test shows when the shoulders are in 
correct position ? How may they be pulled backward and 
what mistake should be avoided in attempting to do this ? 
How common were foot troubles among the drafted men 
during the recent war ? How many bones are there in the 
foot? How are the bones held together? Where are the 
arches in the foot ? Where are the muscles that move the feet 
in walking ? 
Why are high-heeled shoes objectionable ? On what three 
points of the foot does the body weight fall ? What is the 
objection to narrow heels ? to heels that point forward ? to 
shoes with pointed toes ? to tight shoes ? Describe a good 
shoe. What is the correct position for the foot in standing? 
in walking? 
SUGGESTIONS TO THE TEACHER 
Bancroft’s The Posture of School Children (Macmillan) will be 
most helpful to the teacher. The American Posture League, No. I 
Madison Avenue, New York City, issues charts and literature on 
posture and gives the address of manufacturers of clothing, shoes, 
furniture, and other articles that have been designed to meet the 
standards approved by the League. CHAPTER FIVE 
THE HEART AND THE CIRCULATION OF THE BLOOD 
In New York City the street cars, automobiles, and 
wagons fill the streets; the elevated trains roar over- 
head ; and deep in the earth 
the trains in the subway rush 
on and on in a procession 
that never ends. Nor is this 
all of the transportation sys- 
tem of the city ; for water and 
gas are piped underneath the 
streets to the homes of the 
people; most of the wastes 
of the city are carried away 
by underground sewer pipes ; 
and the electricity which 
lights the city and runs much 
of its machinery passes 
silently along wires to the 
places of its use. In these and in many other ways the 
carrying problem of the city is solved. 
The carrying problem in the body. As a city is com- 
posed of a multitude of people, so is the body composed 
of a multitude of cells — 400,000,000,000, according to 
one estimate. Each of these cells must have food and 
oxygen, and each must get rid of its wastes. There 
must, therefore, be a transportation system in the body, 
and it must be one that is always in working order — 
not one that breaks down and fails in its work from time 
to time. Transportation by water is more reliable than 
any other method that has yet been devised, and this is 
the method we find used in the body. 
Fig. 44. Transportation in New 
York City. « 
251 252 
PRIMER OF PHYSIOLOGY 
The carrying in the body done by the blood. All 
through the body there is a great system of tubes, or 
pipes, called blood vessels. Night and day the heart 
pumps the blood through these vessels. Everything 
that the cells need is dissolved in the blood and carried 
to them in the blood stream. Into this stream each cell 
gives off its wastes to be carried away. Thus all the 
carrying within the body is done by the blood, and the 
blood is kept in constant motion through the body by the 
heart. 
Arteries and veins. The blood in its movement, or 
circulation, through the body flows through the same 
channels again and again, always returning to the 
starting point, the heart. We have, therefore, two sets 
of blood vessels in the body,—the arteries, which carry 
the blood from the heart, and the veins, which bring the 
blood to the heart. The large arteries which leave 
the heart send branches to the different parts of the 
body. These branches divide into finer and finer 
branches, called capillaries, which run in among all the. 
cells. Then the capillaries unite into small veins. The 
veins, like the creeks that form a river, keep coming 
together, until finally all of them are united into the 
great veins which carry the blood back to the heart. 
To understand how the blood passes from an artery 
into a vein, think of two trees standing with their trunks 
close together and their tops touching each other. Then 
imagine that the blood flows up the trunk of one tree, 
out into its branches and twigs, then on into the twigs 
and branches of the other tree, and down its trunk. If 
the blood should make a circuit of this kind through the 
trees, its journey would be like the one that it makes THE HEART AND THE CIRCULATION 
253 
left auricle 
valves 
lung 
left 
ventricle 
liver 
intestine 
artery to (eg 
Fig. 45. Diagram showing the circulation of the blood. Note the valves be- 
tween the auricles and ventricles and at the mouths of the great arteries that 
open out of the ventricles. 254 
PRIMER OF PHYSIOLOGY 
when it passes out from the heart through an artery 
and returns to the heart through a vein. 
The heart. The heart lies in the chest with its 
point to the left of the center. Its walls are made of 
strong muscles, and within the 
heart are four chambers, or cavi- 
ties, two on each side. The two 
upper cavities are called auricles; 
the two lower cavities are called 
ventricles. 
The action of the heart. The 
veins pour the blood into the auri- 
cles. Then the walls of the auri- 
cles contract and force the blood 
down into the ventricles. Next, 
the strong walls of the ventricles 
close in on the blood, and drive 
it out into the arteries and all 
through the body. After forcing 
the blood into the arteries, the 
walls of the ventricles relax, and for a moment the heart 
rests. Then again the auricles, contracting on the blood 
that has flowed in from the veins, fill the ventricles, 
and the ventricles pump the blood on into the arteries. 
Place your hand on the left side of your chest, and you 
will feel your heart move as its walls close in on the 
blood and force it onward through the vessels. 
The valves of the heart. In every pump there must 
be.valves to keep the liquid from flowing backward. 
The heart, like other pumps, is provided with these 
valves, — two between the auricles and the ventricles, 
and two at the mouths of the arteries to keep the blood 
Fig. 46. The heart. THE HEART AND THE CIRCULATION 
255 
from flowing backward into the ventricles when their 
walls relax and the chambers open after each beat. In 
Bright auricle^ 
VALVE 
CLOSED 
RIGHT 
AURICLE 
VALVE CLOSED 
valve'open 
[RIGHT VENTRICLE 
RIGHT VENTRICLE. 
Fig. 47. A diagram of the right side of the heart showing the working of 
the valves. When the blood flows into the auricles and the ventricles relax( 
the valves of the heart are as shown in A. When the ventricles contract 
and the blood flows out into the arteries, the valves are as shown in B. 
VALVE 
Figure 45 you can study out where the valves are 
placed, and from Figure 47 you can understand how 
they prevent a backward flow of the blood 
in the vessels and in the heart. 
Tracing the circulation of the blood. 
Trace the circulation of the blood in Figure 
45, and you will see that the heart is a 
double organ ; that the right side sends the 
blood on a short journey through the lungs 
and back to the left side; and that the left 
side drives the blood into the arteries for a 
long journey through all the body and back 
again to the right side of the heart. The 
blood flows through the vessels very swiftly, 
making the journey through the lungs in 
about fifteen seconds, and the long journey 
through the body in less than a minute. 
Fig. 48. A 
diagram of a 
pump. Locate 
the valves and 
explain how 
they work. 256 
PRIMER OF PHYSIOLOGY 
The blood composed of plasma and corpuscles. The 
blood is composed of a liquid part called plasma, and 
of millions of little cells called corpuscles, which float 
in the plasma. About nine tenths of the plasma is 
water. The remainder is composed of dissolved food 
and other materials that are needed by the cells, and 
of the wastes that come from the cells. The corpuscles 
are of two kinds, the red and the white. The red 
corpuscles are so abundant that there are millions of 
them in the smallest drop of blood. 
It is the red corpuscles that give the 
red color to the blood. 
The function of the corpuscles. As 
the blood passes through the lungs, 
it takes oxygen from the air that is 
breathed into the lungs. The oxygen 
is then carried through all the body 
and given up to the cells. This carry- 
ing °f the oxygen is done by the red 
corpicscles. Like little boats floating in 
the blood stream, they take up their 
loads of oxygen in the lungs, carry the 
oxygen out through the body, unload 
it for the hungry cells, and hasten back 
to the lungs for more of the oxygen which the cells 
must have. The importance of this work is shown by 
the fact that when the heart ceases to beat, or when 
a person is under water so that the oxygen is cut off 
from the lungs, the life of the body quickly comes to 
an end. 
The white corpuscles are larger than the red ones and 
are fewer in number. Their work is to kill the disease 
Fig. 49. Red blood 
corpuscles (A) aftd 
white blood corpuscles 
(*)• THE HEART A HD THE CIRCULATION 
257 
germs that get into the body. This subject we shall 
discuss in a later chapter (page 449). 
The lymph. The blood capillaries are so small and so 
abundant among the cells that you cannot stick a pin 
into your tissues anywhere without breaking many of 
them and letting the 
blood escape. The 
capillaries have very 
thin walls, and as 
the blood flows 
thrbugh them some 
of the plasma es- 
capes and passes out 
into the spaces 
among the cells. 
This escaped plasma 
is the lymph, about 
which you have 
already studied 
in the chapter on 
the cells (pages 224 
and 225). 
The lymph a middleman between the cells and the 
blood. In Figure 50 you can see how the cells lie 
among the capillaries, and how they are bathed in 
the lymph that escapes through the thin walls of 
these vessels. The cells, therefore, are not in the 
blood stream, but this stream, so to speak, merely 
passes by the house, and the cells must find some 
way of getting their supplies from the stream into 
the house. This is done through the lymph. As 
the red corpuscles pass along in the capillaries, the 
cell 
lymph 
plasma 
white 
corpuscle 
.red 
corpuscle 
FIG. 50. The cells are bathed in lymph, which 
is plasma that escapes through the thin walls of 
the small blood vessels. (Diagrammatic.) 258 
PRIMER OF PHYSIOLOGY 
oxygen breaks loose from the corpuscles, passes out 
through the walls of the vessels into the lymph, and 
so reaches the cells. In the same way, the foods that 
are dissolved in the plasma make their way out into 
the lymph that surrounds the cells, and the wastes 
that the cells give off pass through the lymph into 
the blood and are carried away. The lymph acts as a 
middleman between the cells and the blood, passing the 
oxygen and food from the blood to the cells, and the 
wastes from the cells to the blood. 
The lymphatic vessels. Among the cells of the body 
there is, besides the blood capillaries, a system of fine, 
thin-walled lymphatic capilla- 
ries. These unite and form 
larger vessels, which finally 
empty into the veins of the 
shoulders. The lymphatic 
vessels act as a drainage sys- 
tem for the body, and their 
function is to gather up and 
drain off the stale, impure lymph from among the cells 
and empty it into the blood. This allows fresh lymph 
to escape among the cells, bringing with it sup- 
plies of food and oxygen. The lymphatic vessels of 
the greater part of the body unite in one great vessel 
called the thoracic duct. This runs up the back of the 
cavities of the abdomen and chest, and empties into the 
large vein in the left shoulder. 
The importance of caring for the heart. The respon- 
sibility of keeping the whole transportation system of 
the body in operation falls on the heart, which is usually 
about the size of the fist of the person to whom it be- 
Fig. 51. Lymphatic vessels in 
the fingers. THE HEART AND THE CIRCULATION 
259 
longs. Night and day, from birth until death, this little 
organ pumps away, giving a stroke oftener than once a 
second. We cannot replace an injured valve in it with a 
new one; it could not stop long enough for that, even 
if we knew how to do it. If it be- 
comes overworked, or if it is poisoned 
by disease germs, there is no second 
pump to take its place while it rests 
and gets into good condition again. 
It is such a wonderful organ that usu- 
ally it gives us little cause for com- 
plaint ; yet there are certain things 
that injure the heart, and for our own 
good we ought to know of these things 
and avoid them. We shall therefore 
mention at this time some of the points 
that are important in the care of the 
heart. 
The heart injured by disease germs. By far the 
most common cause of trouble in the heart is disease 
germs. In diphtheria and scarlet fever the nerves and 
the muscle cells of the heart are so damaged by 
the poisons produced by the germs, that even in the 
mildest cases of these diseases, physicians frequently 
forbid the patient to sit up in bed, because they fear 
the effect of the strain on the heart. Furthermore, the 
heart is often so poisoned by an attack of one of these 
diseases that the nerves and muscle cells never recover, 
and the heart is left weak for life. In other diseases, 
such as pneumonia, rheumatism, and influenza, the germs 
themselves attack the valves and cause them to shrivel 
and harden, so that they allow the blood to leak back- 
Fig. 52. Valves in an 
artery where it leaves 
the heart. There are 
three valves attached 
like loose pockets to 
the wall of the artery. 
When the blood starts 
to flow backward into 
the heart, it catches in 
the pockets, which then 
swing out and close the 
opening into the heart. 260 
PRIMER OF PHYSIOLOGY 
ward, and again the heart is damaged for life. As 
much as possible, therefore, we ought to avoid all these 
germ diseases, — the catching diseases which are so com- 
mon, and which people often carelessly give to each 
other. After an attack of one of these dis- 
eases, hard exercise should be avoided until 
the heart has had time to regain its strength. 
Too much exercise injurious to the heart. 
When the muscles are working, they need 
more food and oxygen and give off more 
wastes than when they are at rest. The 
heart must therefore pump the blood more 
swiftly through the body when we use the 
muscles. This you can prove for yourself 
by noting how much harder and faster your 
heart beats after running or after doing other 
hard work. Indeed, when we take hard and 
long-continued exercise, it is usually the 
heart that becomes tired first of all, although 
we may not feel it. 
There is danger, therefore, of overworking 
the heart, especially at that time of life when 
the boy or girl is entering manhood or 
womanhood and the body rapidly increases 
in size. When overworked, the heart, like 
any other muscle, at first enlarges, and 
then, if the overworking is kept up, becomes weak and 
flabby. This condition of the heart is called “ athletic 
heart.” If a person whose heart has been injured by 
overexercise takes a long rest, going to bed, if neces- 
sary, his heart usually recovers. He ought, however, 
to take care not to force his heart into this condition. 
Fig. S3. A 
valve in a 
vein. The 
veins have 
valves in them 
to prevent the 
blood from 
flowing back- 
ward when 
pres sure 
comes on the 
veins. Run 
your finger 
down a vein 
on your fore- 
arm, and little 
knots will 
stand out on 
the vein at the 
points where 
the valves are 
located. THE HEART AND THE CIRCULATION 
261 
Proper and improper exercise. Do not keep on at 
any heavy work or hard game until you are exhausted. 
Do not play tennis all day. Do not spend a whole 
Saturday afternoon playing football. Remember that 
a baseball pitcher needs a stout heart as well as a 
strong arm, and that, for the sake of both your arm 
and your heart, you should not stay in the pitcher’s box 
a whole half-day at a time. Do not enter long Mara- 
thon races that are intended for men and not for boys, 
and do not get on your bicycle and ride at a fast pace, 
hour after hour, up hill and down. You should under- 
stand, however, that it is only overwork that you are 
being cautioned against, and that both moderate exercise 
and severe exercise taken for short periods, are bene- 
ficial to the heart, as well as to other parts of the body. 
Tobacco injurious to the heart. Tobacco sometimes 
damages the heart until it has a quick, weak, and but- 
tery beat. This is a serious ailment, but usually, if the 
tobacco is given up, the heart seems in time to recover. 
Coaches and trainers will not allow athletes to smoke, 
because smoking weakens both the heart and the other 
muscles. The question of the effects of tobacco on the 
body we shall discuss in more detail in a later 
chapter (page 409). 
The heart injured by headache remedies. A number 
of drugs commonly used (among them phenacetin, ace- 
tanilid, and antipyrin) will check a headache. The prac- 
tice of taking these drugs for headaches and colds is 
dangerous; for they all weaken the action of the heart, 
and their continued use will bring on heart disease. 
They should be taken only when prescribed by a physi- 
cian, and no good physician will prescribe them often 262 
PRIMER OF PHYSIOLOGY 
for the same 'person; for treating a headache in 
this way is not finding and removing the cause of 
the trouble, but drugging the body so that the pain 
will not be felt. 
The effects of alcohol on the heart and blood vessels. 
Alcohol causes the walls of the blood vessels to become 
weak and brittle. For this reason, apoplexy, which is 
caused by the bursting of a blood vessel in the brain, 
is more common among users of alcohol than among 
abstainers. Alcohol often weakens the heart by caus- 
ing its muscle cells to change to fat. In many beer 
drinkers there is the additional trouble that the work- 
ing cells of the heart are buried in a great mass of fat 
that must be lifted and moved every time the heart 
beats. When one realizes that in germ diseases every- 
thing depends on the heart’s keeping at work until 
the body has had time to overcome the germs that are 
attacking it, the disastrous effects of alcohol are more 
easily understood. In pneumonia, especially, when it 
is a great task for the heart to drive the blood through 
the congested lungs, and in diseases in which the 
heart is weakened by the poisons from the germs, it 
is most important that the full power of this organ be 
saved for the ordeal which it must undergo. Statistics 
from a hospital in a city where excessive beer drink- 
ing is very common, show that 16 per cent of all deaths 
in the hospital were due to “ beer-drinker’s heart.” 
Digestive troubles and the heart. When the digestive 
organs are out of order, the stomach sometimes becomes 
filled with gas and presses on the heart, causing a most 
uncomfortable feeling and a pounding and irregular 
beating. The digestive system, of course, should be THE HEART AND THE CIRCULATION 
263 
given proper treatment in cases of this kind, but if this 
is done, there need be no alarm about the heart itself. 
QUESTIONS 
What must be carried to the cells and away from them? 
How is this carrying done? What is the movement of the 
blood through the body called? What is an artery? What is 
a vein? What is a capillary? How does the blood pass from 
an artery into a vein? 
Describe the heart. Explain how the heart forces the blood 
through the body. Where are the valves in the heart and what 
is their use? Trace the circulation of the blood from the right 
auricle back again to the right auricle. 
Of what is the blood composed? Of what is the plasma 
composed? What is the function of the red corpuscles? of 
the white corpuscles? What is the source of the lymph? Ex- 
plain how the lymph acts as a middleman between the cells 
and the blood. Describe the lymphatic vessels. What is their 
function? What and where is the thoracic duct? 
Why is the care of the heart so important? What is the 
most common cause of injury to the heart? How does over- 
exercise affect the heart? At what age is the heart especially 
likely to be injured by overexercise? Name some games that 
put a great strain on the heart. 
What effect has tobacco on the heart? Name some drugs 
that are commonly used as headache remedies. What effect 
have these drugs on the heart? How do they relieve a head- 
ache? What effect has alcohol on the blood vessels? What 
causes of death are especially common among drinkers on 
account of this effect of alcohol on the vessels? What effect 
has alcohol on the heart? When is the bad effect of alcohol 
on the heart especially likely to show itself? What effect does 
indigestion sometimes have on the heart ? 264 
PRIMER OF PHYSIOLOGY 
SUGGESTIONS TO THE TEACHER 
If possible, secure a glass model of a pump, such as is commonly 
found among the equipment of an elementary physical laboratory, 
and demonstrate the action of the valves. Allow the pupils to ex- 
amine a drop of blood under the microscope. Additional matter on 
the topics discussed in this chapter and in many of the other chapters 
in this book will be found in Human Physiology, the most advanced 
book of the series. 
An examination of the diagram on page 445 will show that heart 
disease is one of the great causes of death. It is now generally 
accepted that practically all cases of heart disease (as well as cases 
of rheumatism, Bright’s disease, and disease of the arteries) are 
caused by germs. Usually these germs are slow-growing races of 
streptococci, and often they have a permanent breeding ground in 
the tonsils, at the roots of teeth, in the bones of the face, or in some 
other part of the body, and are carried from these “ foci of infec- 
tion ” to the heart and other organs. In overcoming these slow 
infections, a hygienic life is of great importance, but treatment of the 
teeth or other infected part is often necessary. The relation of 
these chronic infections to the general health should be brought to 
the attention of the class during the study of later chapters. CHAPTER SIX 
Fill a bottle with boiled water and one with unboiled 
water, and arrange growing beans in them, as is shown 
in Figure 54. The bean with its roots 
in unboiled water will grow for a consid- 
erable time — as long as the mineral mat- 
ter in the water will provide it with food 
materials. The roots of the plant in the 
boiled water will quickly die and the 
whole plant will then wither, because 
the roots no longer send the water up to 
the leaves. 
Why is it that the roots in the boiled 
water die? The answer is simple. The 
boiling of the water drives the oxygen out 
of it, and without oxygen the cells of 
neither plants nor animals can remain 
alive. 
The object of respiration. The first object of respiration 
is to take oxygen into the body. Of food, we have enough 
stored in the body to maintain life for a number of days, 
or, in some cases, even for several weeks. As to 
oxygen, however, the body leads a hand-to-mouth 
existence; for though the air is more than one fifth 
oxygen, there is not enough of this gas in the body to 
keep us alive for more than two or three minutes 
after breathing has stopped. While we sleep, there- 
fore, we must keep on breathing in oxygen ; sit as quiet 
as we may, we must still keep on taking it in ; and when 
we walk or run, we do it taking in oxygen as we go. 
The second object of respiration is to give off carbon 
RESPIRATION 
Fig. 54. 
265 266 
PRIMER OF PHYSIOLOGY 
dioxidfrom, the body. Carbon dioxid is a waste gas that 
is all the time being formed in the cells and carried by 
the blood to the lungs, 
to be breathed cut into 
the air. It is formed 
not only in the body, 
but where wood, coal, 
oil, or gas is burned, 
and it is sometimes 
found in coal mines, 
where it is known to 
the miners as “ choke 
damp.” 
The cavity of the 
chest. The cavity of 
the chest contains the heart and the lungs. This cavity 
is inclosed by the ribs and sternum, and is separated 
from the abdominal cavity below by a thin cross-parti- 
tion called the diaphragm. In breathing, the chest cav- 
ity is enlarged by lifting the ribs upward and outward, 
and by pulling the diaphragm downward. 
The trachea and the lungs. The trachea has in its 
walls stiff rings of cartilage that hold it open so that the 
air can pass freely through it to and from the lungs. 
At its base the trachea divides and sends a great branch 
to each lung. Within the lungs these branches divide 
again and again, until finally they end in little, thin- 
walled air sacs. The branches of the trachea are called 
the bronchial tubes, and the lungs have a light, spongy 
texture because they are composed chiefly of these tubes 
and of the air sacs in which the tubes end. 
The changes in the air in the lungs. The walls of the 
Fig. 55. The chest, showing the position of 
the heart and lungs. RESPIRATION’ 
267 
air sacs are very thin, and great numbers of small blood 
streams constantly flow through the capillaries in them. 
The oxygen of the air that we take into the lungs 
passes into the blood through the walls of the sacs, and 
trachea 
lung 
air sacs 
bronchial tube 
Fig. 56. The lungs. 
the carbon dioxid that is in the blood passes out into the 
air that is in the sacs, and is then breathed out of the 
lungs. The air in the lungs, therefore, loses oxygen and 
gains carbon dioxid, and the blood takes in oxygen and 
gives up its carbon dioxid. 268 
PRIMER OF PHYSIOLOGY 
These changes take place very rapidly in the lungs, 
for the capillaries are so numerous that they cover more 
than one third of the surface of the air sacs, and all the 
blood in the body goes through them in a little over a 
ninute. 
Injury done to the respiratory organs 
3y dust. Nearly all the diseases of the 
nr passages and lungs are caused by 
jerms. Dust wounds and injures the 
ielicate lining of these parts, and makes 
t easy for germs to gain an entrance 
nto the tissues. The majority of work- 
men in certain industries, such as metal grinders, pot- 
ters, and workers in cotton and woolen mills, die of 
pneumonia, tuberculosis, and other respiratory diseases. 
This is due to the multitude of 
tiny wounds continually being 
made in the walls of the air 
passages by the sharp dust 
and fine fibers with which the 
air of many factories and mills 
is laden. Much can be done 
to make dusty trades more 
healthful by using water in 
operations where dust is 
formed, by hoods and air 
blasts that suck up the dust 
from machines, and by the 
workmen wearing appliances 
to protect themselves from the 
dust. 
Sweeping without raising a dust. In many states 
Fig. 57. A small 
bronchial tube and the 
air sacs in which it 
ends. 
Fig. 58. A workman wearing a 
mouthpiece to protect himself 
from dust. {From a photograph 
by the Massachusetts State Board 
of Health.') RESPIRATION 
269 
dry sweeping of school buildings and of other public 
buildings is forbidden by law, because it stirs up great 
quantities of dust, which then remains floating in the 
air for hours. The best method of cleaning public 
buildings, as well as private homes, is the vacuum pro- 
cess. When this cannot be used, wet sawdust, a sweep- 
ing compound, or something 
else effective should be em- 
ployed to keep down the dust. 
One device that is sometimes 
used is a can attached to the 
handle of a broom and so ar- 
ranged that it keeps the broom 
moist with kerosene or water. 
The floor brush shown in Fig- 
ure 59 is very satisfactory for 
sweeping, and paraffin oil is 
extensively used in making up 
floor dressings and sweeping compounds. This oil may 
be purchased for ten cents a quart, or at a lower price 
in larger quantities, and it gives an excellent polish to 
floors and furniture. Sawdust moistened with it makes 
a very satisfactory sweeping compound, and a cloth 
dampened with it is the best thing for removing dust 
from furniture and for cleaning doors. 
Gaseous impurities in the air. In many houses small 
quantities of gas are constantly escaping from the pipes, 
and often this leaking of gas is allowed to run on 
for weeks and months before the pipes are repaired. 
Breathing this gas, especially if it is water gas, is most 
injurious to the health. Another most harmful practice 
is the use of gas and oil stoves that have no pipes to 
Fig. 59. A dustless brush. The 
back of the brush is hollow and 
is filled with kerosene, which 
slowly trickles down and keeps 
the bristles moist while the sweep- 
ing is being done. 270 
PRIMER OF PHYSIOLOGY 
carry away the fumes; for it is ruinous to the health 
to breathe the poisonous gases that come from them. 
The effect of tobacco on the respiratory organs. To- 
bacco smoke is hot and irritating and often causes sore 
tongue and “ smoker’s sore throat.” Undoubtedly these 
diseases sometimes lead to cancer, because any part of 
the tissues that is constantly irritated may develop into 
a cancer. When the smoke is inhaled into the lungs a 
sooty deposit which must certainly be injurious is left on 
the walls of the bronchial tubes.1 When smoke is ex- 
haled through the nose it has a tendency to cause ca- 
tarrh and injures the sense of smell. The nicotin that 
is taken into the blood, either by partially paralyzing 
the nerve centers that control the breathing muscles, 
or by its effect on the muscles themselves, causes the 
shortness of breath with which every smoker who has 
tried to take part in athletic sports is familiar. 
QUESTIONS 
Why will a plant die if its roots are in boiled water ? What 
is the first object of respiration? Why can a person live a 
long time without eating, but only a few minutes without 
breathing? What is the second object of respiration? 
What organs are in the cavity of the chest? By what is the 
chest inclosed? How is the chest cavity enlarged in breath- 
ing? Describe the trachea and its branches. How do the 
bronchial tubes end ? Explain the changes that take place in 
the air in the lungs. 
1 “ Surely smoke becomes a kitchen far better than a dining chamber, 
and yet it makes a kitchen oftentime in the inward parts of man, soyling 
and infecting them with an oyly kind of soote as hath been found in some 
great tobacco takers, that after their death were opened.” — King James I, RESPIRATION 
271 
Why is breathing dust dangerous? What may be done to 
keep down dust in factories? How may buildings be swept 
without raising a dust? Why should leaks in gas pipes in 
houses be carefully looked after? Why is it injurious to use 
gas or oil stoves that have no pipes to carry away the gases? 
Have a pupil breathe through a glass tube into limewater. The 
white precipitate is calcium carbonate, which is formed by the union 
of the carbon dioxid with the calcium in the limewater. 
Call attention to the dust particles which may be seen floating in 
the air when a beam of sunlight penetrates a darkened room. Use 
all possible influence to have the school building swept and dusted 
in a sanitary manner. Call attention to the importance of hygienic 
industrial conditions and to the fact that, in selecting an occupation, 
the effect of the work on the health is as deserving of consideration 
as the wages that may be earned. 
SUGGESTIONS TO THE TEACHER CHAPTER SEVEN 
VENTILATION 
Fig. 60. Move your bed out into the open air if it is possible for you to do so. 
In 1758, during a rebellion of the native soldiers in 
India, one hundred and forty-six Englishmen were shut 
up overnight in a room that had but a single window. 
When morning came, only twenty-three of them re- 
mained alive. After the battle of Austerlitz, three 
hundred prisoners were crowded into a cavern. In a 
few hours two thirds of them were dead. Many other 
instances are on record of people who have perished 
when shut up in closets, vaults, or the holds of ships. 
Most persons have read of some of these instances, and 
practically every one takes care to keep out of places 
where he is likely to perish because his supply of air 
fails. 
272 VENTILATION 
273 
It would seem, however, that many persons are like 
the kind-hearted old gentleman who could not bring 
himself to cut his dog’s tail off all at once, and so cut 
off an inch each morning until the tail was gone; for 
while these people object most decidedly to killing their 
bodies all at once with bad air, they do not seem to 
mind killing them a little at a time. Perhaps they do 
not realize what they are really doing, but the damage 
is constantly being done, nevertheless; for they go to 
churches, lecture halls, and theaters where the air is 
so foul that it gives them headaches; many persons 
sleep in rooms with windows and doors so tightly 
closed that the sleepers must breathe the same air 
again and again; children often cover their heads with 
the bedclothes and do not get a breath of fresh air all 
night long; ana many schools and factories are so 
badly ventilated that the health and the working power 
of those in them are continually being undermined. 
The whole subject of ventilation is, therefore, of the 
very greatest importance, and in this chapter we shall 
take up the study of why we need fresh air and how 
to get it. 
Enough oxygen usually in the air. About one fifth 
(21 per cent) of the air is oxygen, and the remainder is 
nearly all nitrogen. The nitrogen is not used in the 
body, but is simply breathed into the lungs and breathed 
out again unchanged. The oxygen is taken into the 
blood and carried through the body to the cells. Air 
that has been breathed once has lost about one fourth 
of its oxygen, and where people are crowded together 
as the English were in the “ Black Hole of Calcutta,” 
the oxygen in the air becomes exhausted. We can live, 274 
PRIMER OF PHYSIOLOGY 
however, on 15 or even on 12 per cent of oxygen, 
and under any ordinary conditions the trouble with 
the air we breathe is not with the amount of 
oxygen in it. 
The carbon dioxid problem. Carbon dioxid is given 
off into the air from the lungs, and too much of it in 
FIG. 61. An outdoor lesson in geography. (After Ayres.) 
the air is poisonous to us. It was long supposed that 
this was the chief trouble with indoor air, — that the 
paleness and lack of strength noticed in those who lived 
without good ventilation were due to carbon dioxid 
poisoning. All our rules for ventilating buildings have 
been laid down with the idea that we must bring in 
large quantities of fresh air (3000 cubic feet per hour 
for each person) to keep the carbon dioxid from be- 
coming too abundant in the air that we breathe. This 
is still a good rule to follow; for it has not yet been 
proved that breathing large amounts of carbon dioxid 
week after week is not injurious to the health. Re- 
cently, however, it has been proved that in ventilation VENTILATION 
275 
other questions besides the amount of carbon dioxid in 
the air must be considered. 
Dry air injurious. In rooms heated by stoves, radi- 
ators, or hot-air systems, the atmosphere becomes too 
dry, unless special arrangements are 
made for moistening it, — drier, in 
fact, than is the air in the Desert 
of Sahara. Since dry air quickly 
evaporates the sweat from the skin 
and cools the body, people often 
heat such rooms up to 75 or 80 de- 
grees, because they feel cold at lower 
temperatures. 
Living in a hot, dry atmosphere of 
this kind is injurious to the eyes, and 
it makes people subject to colds; it 
causes nervousness, also, and a child 
in a dry, overheated schoolroom is 
restless and has difficulty in keeping 
his mind on his work. Vessels of 
water should therefore be kept in furnaces and on stoves 
and radiators; and in school buildings heated with hot 
air, arrangements should be made to moisten the air be- 
fore it is discharged into the rooms. It is economy to 
give attention to this point; for moist air feels as warm 
at 65 degrees as dry air at 75 degrees; in some school 
buildings as much as a 10 per cent saving in fuel has 
followed the installation of devices for moistening the 
air. 
A moist atmosphere and overheating. When the tem- 
perature of moist air rises much above 70 degrees, it 
gives us a hot, suffocating feeling, similar to that 
Fig. 62. A home-made 
humidifier — a pail with 
a strip of cloth arranged 
for feeding the water up 
and letting it evaporate 
into the air. 276 
PRIMER OF PHYSIOLOGY 
which one has on a warm, sultry summer morning. The 
explanation of this is that the moisture in the air keeps 
the sweat from evaporating, and there is a layer of hot, 
wet air surrounding the body like a shell. In crowded 
buildings, therefore, where the air is wet from many 
people breathing it, a proper temperature is very im- 
portant. It ought not to fall below 65 degrees, for then 
the people will be chilly; and it ought not to run above 
70 degrees, for then the people will become hot and un- 
comfortable, some of them will develop headaches, and 
many of them will catch cold when they step out into 
the cool outside air. 
The necessity for motion in the air. In hot weather, 
and in warm and wet indoor atmospheres, it is most 
important that there be air currents to break up and 
blow away the hot, moist air blankets that surround us. 
How important such air currents are, is shown by an 
experiment that was carried out in England. In this 
experiment, a group of students were closed in a small 
room and watched through a glass in the door. At 
first they were laughing and joking, but soon they began 
to show signs of distress. Formerly it would have 
been concluded that they were suffering from a lack of 
oxygen or were being poisoned by carbon dioxid. The 
real trouble, however, was the overheating and the mois- 
ture in the air, as was proved by the fact that when an 
electric fan was started in the room, the students be- 
came comfortable again without the introduction of fresh 
air. 
Setting indoor air in motion. In public buildings the 
air often becomes close and the temperature rises after 
meetings have been in progress for some time. In such VENTILATION 
277 
cases a great deal can be done towards keeping the 
audience comfortable by opening a few windows, so 
that part of the heated air will escape and currents will 
be set up through the building. 
In the Chicago schools, every 
window in every schoolroom is 
thrown wide open three times 
a day to allow the wind to 
sweep out the stale air in the 
buildings and to break up and 
blow away the envelopes of 
moist air from about the bodies 
of the pupils. Practices like 
this should be followed every- 
where. A few minutes de- 
voted to flushing out a school- 
room and going through a few 
resting and stretching exer- 
cises are by no means to be counted as lost, for the 
pupils return to their work with new vigor and zeal. 
It is well to understand also that the health of many 
workers could be improved and their working power 
greatly increased by providing them with electric fans 
during the hot summer weather. Many factory owners 
who have put in ventilating systems have found that the 
increased amount of work accomplished by the laborers 
in the factory far more than paid the cost of putting in 
and operating the system. This is what we should ex- 
pect, for every one knows the difficulty of working in 
an overheated, stifling atmosphere, and how bracing 
and invigorating a current of air is on a hot, oppres- 
sive day. 
FlG, 63. A window board helps 
to ventilate a room. 278 
PRIMER OF PHYSIOLOGY 
Disagreeable odors in crowded rooms. In crowded 
and heated rooms, odors always arise that cause head- 
ache and a feeling of faintness in persons who are sen- 
sitive to them. A low 
temperature makes 
these odors much less 
noticeable, and a cur- 
rent of fresh air 
through the room not 
only sweeps away the 
odors themselves, but 
also refreshes the 
people and destroys 
the effects of the odors on them. Persons who are 
troubled with symptoms of illness when they attend 
public meetings can sometimes escape the difficulty by 
arranging for a seat near a ventilator or window, or 
where a current of air from an open doorway will blow 
across them. It is probable that “ crowd poisoning ” 
is nothing but the effect of the overheating and of the 
odors that are usual in buildings where many people are 
assembled. 
Open-air schools. In Oakland, California, during the 
winter of 1910-1911, an open-air school was in operation. 
In this school the children did regular work, and they had 
no special feeding or rest periods. Yet during the first 
half year no child in the school failed to gain in weight, 
and the average gain was 3.70 pounds; in the regular 
school building the average gain was 2.36 pounds. The 
children in the open-air school were free from colds, 
while, as usual, the children in the indoor school at times 
suffered from them. Most noticeable of all, however, 
Fig. 64. An open-air schoolroom in Sacra- 
mento, California. The inclosed room is 
used only in bad weather. VENTILATION 
279 
was the wide-awake, energetic way in which the open-air 
pupils kept at their work. Day after day they finished 
their tasks without becoming tired, and by the end of 
the year all of them had advanced one grade, several of 
Fig. 65. An outdoor classroom at Williamsburg, Virginia. When the 
children become tired indoors, classes are taken to this building for a recitation. 
There were only 20 days during the winter of 1911-1912 on which this outdoor 
classroom was not used. 
them had advanced two grades, and one boy had done 
two and one half years’ work in the one year. 
In many places open-air schools have been established 
for sick children, with the idea of nursing them back to 
health rather than of advancing them in their school 
work. In these schools the pupils are fed and have 
long rest periods, and only light school work is done. 
Experience has shown, however, that in the open air 
the children throw themselves into the work so eagerly 
and their minds are so clear that even in outdoor schools 
that give only half the usual time to study, the pupils 
advance as rapidly as they do in an indoor school 
where they spend the whole day over their books. 280 
PRIMER OF PHYSIOLOGY 
Why, then, should not boys and girls who are in good 
health, as well as those who are sick, be in schools where 
they can master their work with the greatest ease and 
at the same time build up their bodies by breathing out- 
door air ? The time 
has come when each 
community must an- 
swer this question. 
In mild climates and 
in warm weather, 
there is certainly no 
reason for going to 
the great expense of 
trying to get the right 
kind of air indoors, 
when nature has filled 
all outdoors with exactly the kind of invigorating air 
that we need. 
Outdoor sleeping. In recent years thousands of out- 
door sleeping porches have been built in our country. 
Without a doubt the health is greatly benefited by 
passing in the open air the many hours that we 
spend in sleep. The only point that needs to be re- 
membered in moving outdoors is that the warmth of 
the body must be kept up; that man moved into houses 
to protect himself from the cold and wet, and when 
he moves out of them again he must have clothing that 
will keep him warm and dry. If this point is looked 
after, the more time we spend outdoors the better. 
Therefore, move out into the outdoor air to sleep if you 
can, and if you cannot do this, open wide the windows 
of your bedroom and let the outdoor air come to you. 
Fig. 66. Open-air classes held on the roof of 
the Horace Mann Elementary School, Teachers 
College, New York. VENTILATION 
281 
QUESTIONS 
What two gases make up the greater part of the air ? Which 
of these gases is used by the body? Under what conditions 
may the oxygen supply of the air become exhausted? 
What is carbon dioxid ? How much fresh air is supposed 
to be needed by each person in a building ? Why does dry 
air cause a sensation of chilliness ? What bad effects follow 
living in a dry atmosphere? Is there any method of moisten- 
ing the air used in your school building or in your home? 
Explain how it works. 
Why does one easily become overheated in a moist atmos- 
phere? Describe an experiment that proved the importance 
of keeping the air in motion. Mention some ways by which 
air currents may be set up in buildings. In what way have 
factory owners been repaid for the cost of installing and 
operating ventilating systems? 
What .effects have the odors of crowded rooms on certain 
persons? What may be done to make these odors less notice- 
able? 
Give an account of the open-air school at Oakland, Califor- 
nia. For what purpose are open-air schools used in many 
places? What advancement do the pupils in these schools 
make in their school work? In outdoor life what point must 
be kept in mind ? 
Give gymnastic exercises while the schoolroom windows are 
opened. Insist on the importance of the pupils putting their knowl- 
edge of ventilation into practical use in their home life. 
Perform for the class experiments with wet- and dry-bulb ther- 
mometers (consult Appendix of Human Physiology'). Bring out that 
because the skin is kept moist by the perspiration the body is com- 
parable to a wet-bulb thermometer, and that it is the wet-bulb rather 
than the dry-bulb temperature that is important in regulating the 
temperature of rooms. 
SUGGESTIONS TO THE TEACHER CHAPTER EIGHT 
ADENOIDS AND COLDS 
Fig. 67. Adenoids sap the strength so that any one who is suffering from 
them has very little chance of being the best athlete in the school; they dull the 
mind so that the victim of them rarely stands at the head of his class. 
Among the most common of all the ailments that 
afflict the inhabitants of the temperate and frigid re- 
gions of the earth, are colds and certain other troubles 
of the nose and throat. These maladies, of course, are 
not so severe as many other diseases, but certainly they 
cause more inconvenience than all our other lesser sick- 
nesses combined. It is true also that they often weaken 
the body and lay the foundations for other serious diffi- 
culties. People lack the general understanding of these 
diseases that they ought to have, and in this chapter we 
shall therefore make a study of them. In order that 
we may do so more intelligently, we shall first consider 
the structure of the nose and throat. 
The chambers of the nose. The air passes through 
the nostrils into the nasal chambers. These long, nar- 
row passages are about three quarters of an inch wide; 
282 ADENOIDS AND COLDS 
283 
they extend up into the head about as high as the level 
of the eyes, and they run back and open into the throat 
behind the mouth. They are 
separated from each other by 
a very thin, bony partition. 
On the outer wall of each 
chamber are three curved and 
rolled-up bones that stand out 
in the pathway of the air (Fig. 
68). The whole interior of 
the nasal chambers is lined by 
the same skin-like mucous 
membrane that is found in the 
mouth and throat. This is 
kept moist by a sticky sub- 
stance called mucus. 
The air warmed and cleansed in the nose. The air in 
the nose comes in contact with the lining of the chambers, 
and is drawn in among the bones that stand out in the 
nasal passages. In this way the air is warmed, and the 
dust and germs in it are caught on the moist, sticky 
mucous membrane that lines the cavities and covers the 
bones. The function of the nose in respiration is to protect 
the throat and lungs from cotd and from dust and germs. 
Troubles in the nose. Sometimes the thin partition 
between the two sides of the nose becomes bent so that 
it closes one of the nasal chambers; sometimes the 
bones in the nose enlarge until they interfere with the 
breathing and prevent the proper drainage of the nose; 
and in a considerable number of persons, swollen and over- 
grown portions of the mucous membrane, called nasal 
polyps> block the air passages. In all such cases, the 
Fig. 68. A cross-section of the 
nasal chambers, showing the bones 
(a, 6, and c) that stand out in the 
pathway of the air. The mucous 
membrane lining the chambers is 
shown in white. 284 
PRIMER OF PHYSIOLOGY 
obstruction in the nose ought to be removed by a physi- 
cian who understands how to do the work. If this is not 
done, the breathing will be interfered with continually, 
and colds and chronic catarrh are likely to be the result. 
The throat. The throat is a funnel-shaped cavity 
which curves backward and downward around the base 
of the tongue. 
At its bottom are 
two openings, one 
leading to the 
stomach and one 
leading to the 
lungs. In front, 
a little flap-like 
structure, the soft 
palate, hangs 
down from above 
and partly sepa- 
rates the throat 
from the mouth. 
Above and behind 
the soft palate 
are two openings 
which lead into 
the nose, and high up in the walls on either side of the 
throat are the mouths of the two Eustachian tubes, 
which are small passageways that lead to the middle 
ears (Fig. 69). In the walls of the throat are four 
tonsils, which we shall describe in some detail. 
The tonsils. One small tonsil lies in the back of the 
tongue; one is high up in the back wall of the throat; 
and the other two lie in the side walls of the throat. 
Eustachian tube 
soft palate 
position of 
adenoids 
v tonsil 
Fig. 69. The nasal passages, mouth, and throat. ADENOIDS AND COLDS 
285 
These structures are composed of loose, spongy tissue, 
and leading down into them are small openings, or crypts, 
which are formed by folding the mucous membrane down 
into deep little pockets (Fig. 70). Germs 
grow in these pockets and cause tonsillitis, 
— a disease in which the tonsils are swollen 
and have matter in them like that found 
in boils. In many persons the tonsils are 
always infected with germs and become so 
swollen and enlarged that they block the 
throat and interfere with the breathing. 
The tonsil which is most commonly en- 
larged is the one in the back wall of the 
throat, and the spongy, swollen, whitish mass of soft 
tissue into which this tonsil changes is called adenoids, or 
adenoid growths. Usually, when adenoids are present, 
the other tonsils also are enlarged, but this is not 
always the case. 
The symptoms of adenoids. In moist climates one 
fourth of all the children may have adenoids. The most 
easily recognized symptom of them 
is mouth breathing. If the throat 
is entirely blocked by them and the 
tonsils also are enlarged, the mouth 
will be kept open so wide that any 
one will notice that the child is a 
mouth breather. If the throat is 
only partly filled, the child may keep 
his mouth open only a little, and the 
mouth breathing may not be noticed 
at all, except when the child has a 
cold or is asleep. After the adenoids 
Fig. 70. A ton- 
sil. A part of the 
tonsil is cut away 
to show a crypt. 
Fig. 71. Adenoids in the 
throat seen from the front. 
(After Wingrave.) 286 
PRIMER OF PHYSIOLOGY 
have been growing for some time, the upper teeth begin 
to turn forward; the face is puffed out under the eyes ; 
the eyes have a strained look and are drawn down at 
the inner corners; the lips thicken; the upper lip 
shortens and is turned out; there is 
often a white line running down from 
the corner of the nose marking off the 
division between the cheek and lip; and 
the whole face has a dull, stupid look. 
In many cases of adenoid growths, 
the germs work their way up the Eusta- 
chian tubes and cause earache, which 
is an almost certain symptom of them. 
They also interfere with speech, and any 
one who “ talks through his nose ” or has difficulty in 
pronouncing his words clearly, probably has his nasal 
passages blocked by them. A child with this trouble 
usually snores, and in bad cases sometimes gasps and 
struggles for breath during sleep. 
Besides these symptoms of adenoid growths, there are 
certain other effects that often go with them. Sometimes 
children who have them are very restless and nervous, 
and are unable to keep their attention fixed on any one 
thing. Often they are stupid at their books and fall 
behind in their school work. Usually the digestion is 
disordered from swallowing the multitudes of germs 
that come from the adenoid and tonsils. Often the 
chest is narrow and the child is undersized, — some- 
times two or three years smaller than he should be. 
Another effect of adenoids, very noticeable in some 
cases, is a fretful, quarrelsome, and seemingly perverse 
disposition, — a lack of self-control and a tendency to 
Fig. 72. Adenoid 
growth that has been 
removed. One half 
natural size. (After 
Wingrave.) ADENOIDS AND COLDS 
287 
fly into a rage at the slightest provocation. This causes 
the victim to make trouble for his parents, for his teacher, 
and for all who have anything to do with him. 
The remedy for adenoid growths and infected tonsils. 
The only thing to do for adenoids and infected tonsils is 
to have them out at once. When performed by a skilled 
Fig. 73. Typical adenoid faces. 
surgeon this operation is not severe, and in thousands of 
cases it has resulted in an improvement in the condition 
of the child that is almost miraculous. One sixteen-year- 
old boy gained fourteen pounds in three weeks after hav- 
ing his adenoids and tonsils removed ; and it is a common 
thing for a child whose adenoid growths have been taken 
out to make a sudden increase in height and weight and 
to renew his interest in his school work. 
The evil consequences of waiting to outgrow adenoids. 
Usually, but not always, adenoids disappear by the time 288 
PRIMER OF PHYSIOLOGY 
a person is grown.1 % It must not be thought, however, 
that their evil effects disappear with them; for if the 
nostrils are not used in breathing, the nasal chambers 
and the upper part of the face do not grow as they 
should, and the person is left with narrow air passages, 
protruding upper teeth, a short, thick upper lip, and 
often with a catarrh and a swollen condition of the nasal 
mucous membrane that will remain with him for life. 
Neglected adenoids spoil the beauty of the face for all 
time, and it is estimated that three fourths of all deaf- 
ness is due to them. Any one who advises waiting to 
outgrow adenoids is giving the worst advice possible. 
They ought to be removed, and this ought to be done be- 
fore they interfere with the growth of the bones of the 
nose and face. 
Colds. Colds are caused by germs that live on the 
mucous membrane of the nose and throat. They may 
be divided into two classes, — epidemic colds and chronic 
colds. Epidemic colds are caused by germs of a particu- 
larly virulent strain that are handed from one person to 
another until the disease sweeps the community. Most 
of us must either endure these colds or find a way to 
escape the germs that cause them — no easy thing to do 
when people who have colds insist on shaking hands 
with us and leaving with us a few millions of the germs 
with which they are so bountifully supplied. 
Spraying the nose with something that will kill the 
germs often helps to check a cold in its early stages. 
1 A case of adenoids has been reported in a child six weeks old and 
one in a man of seventy years. They are by no means to be thought of as 
a disease of children only, for many cases are found in persons up to forty 
years of age. ADENOIDS AND COLDS 
289 
A hot foot bath cannot kill the germs in the nasal pas- 
sages, but it helps to draw the blood away from the 
congested parts and assists in correcting the disturbances 
of the circulation that accompany a cold. It may also 
relieve to some extent the headache from which the 
victim of a violent cold suffers. A hot bath taken be- 
fore going to bed is even better than a foot bath for 
drawing the blood away from the congested parts. 
In chronic colds, the germs remain with the person 
all the time, growing only a little when he is in good 
health and offers a vigorous resistance to them, and 
springing into greater activity whenever the person gets 
his feet wet, becomes chilled, loses sleep, or does any- 
thing else that weakens his body and lowers its resist- 
ance to germs. A person with a cold of this kind is 
like a country invaded, but not conquered, by an enemy. 
At one time the inhabitants of the country drive back 
the foe and give themselves a breathing spell; at an- 
other time the advantage is with those who make the 
attack. The patient’s only hope of victory over his germ 
enemies is to build up his health until his body has suf- 
ficient fighting powers to drive them out completely. 
The following practices have been found important in 
giving the body strength for this work : — 
Clearing out the nose and throat. Adenoids, enlarged 
tonsils, bent and enlarged bones in the nose, and any- 
thing else that prevents a free passage of the air through 
the nose and a free drainage of the mucus from it, turn 
the nasal chambers into splendid homes for countless 
germs. The battle against colds is a battle against 
germs, and we cannot hope to succeed if the enemy is 
intrenched behind fortifications. 290 
PRIMER OF PHYSIOLOGY 
Getting enough fresh air. Experience with both 
consumptives and well persons shows that no one thing 
is so important as fresh air in giving the body the 
power to kill germs. Many persons suffer continually 
from colds because they live and work in buildings 
where the air is dry and overheated, and any one who 
wishes to free himself from a chronic cold must include 
fresh air in his plans. 
Keeping the bowels open. When refuse matter does 
not pass promptly through the intestines, it putrefies 
and produces poisons that break down the health of the 
whole body (pages 391-392). These poisons destroy 
the power of the body to resist germs, and they injure 
the nervous system so that the blood vessels are not prop- 
erly controlled. The feet of persons who are in this 
condition are therefore often cold while other parts of 
the body are congested with blood, and the circulation 
in general is not regulated as it should be. This disturb- 
ance of the circulation is in itself favorable to the 
growth of germs and makes the cure of a cold difficult. 
The remedy is to get the digestive system into good 
working order, and many persons recover from chronic 
colds when they do this (pages 382-393). 
Taking cold baths. The practice of taking cold 
baths helps to give freedom from colds. Probably one 
way that it does this is by bringing out the white blood 
corpuscles that kill germs; for it is found that the 
white corpuscles are more abundant in the blood after 
a cold bath than before it. Another way that a cold 
bath helps is by teaching the blood vessels in the skin 
to open and close promptly. When cold strikes the 
body, these vessels ought to close and thus keep the ADENOIDS AND COLDS 
291 
blood in the inner parts where the heat of the body will 
not be lost. Then, when the cold is removed from the 
skin, the vessels ought to open and allow the blood to 
come to the surface of the body. In some persons who 
are in bad health, the nervous system which governs 
these vessels does not control them properly, and the 
vessels in the skin may not close promptly enough to 
prevent the escape of the heat from the body; or, at 
the slightest feeling of cold on the skin, the blood vessels 
may shut up tight and gorge the inner parts of the body 
with hot blood, while the skin is left cold and shivering.1 
Cold baths help to train the vessels of the skin to 
open and close properly, and to keep the right amount 
of heat within the body. In beginning to take baths of 
this kind, intelligence and care are necessary ; otherwise 
much harm may be done (page 300). 
Drafts and colds. People are sometimes advised to 
pay no attention to drafts and to open the windows, 
no matter how cold the weather may be, because it is 
germs and not drafts that cause colds. Yet many 
persons know from their own experience that sitting in 
a cold draft does cause them to sneeze, to feel chilly, 
and often to become actually sick. How can the idea 
that it is beneficial to the health to sleep where the 
wind will blow over you, be reconciled with the idea 
that a draft of cold air is dangerous? If motion in the 
air is desirable, why not have as much of it as possible ? 
1 It should be understood that in chills, such as we have in malaria or 
at the onset of grip or pneumonia, the difficulty is that the blood has been 
driven to the inner parts of the body, and the skin, where our sense of 
feeling is, no longer is warmed by the blood flowing through it. There is 
no lack of heat in the body, for often a person has several degrees of fever 
it the same time that he is having a chill. 292 
PRIMER OF PHYSIOLOGY 
In the first place, it must be understood that drafts of 
cold air take the heat out of the skin, and that a person 
who is exposed to them should have sufficient extra 
clothing to enable him to keep up his body heat. This 
keeping up of the body temperature is fundamental in 
the preservation of the health, for the resistance of the 
body to germs is weakened at once by the loss of too 
much heat. Much damage maybe done by compelling 
school children who have been accustomed to hot rooms 
to sit in their ordinary clothing with the windows wide 
open on a cold day. 
In the second place, it must be recognized that persons 
who have chronic colds — those who are carrying a 
host of germs just ready to break through their resist- 
ance and put them to bed — are already sick. It must 
also be recognized that what is safe for a well person 
or for one accustomed to it, may be neither safe nor 
wise for a sick person or for one not accustomed to it. 
When cold air strikes a person who is in a half-sick 
condition, the vessels in the skin close more than they 
should. The result is that the blood is driven inward, 
so that in a few minutes the person can feel the mucous 
membrane in his nose swelling from the great supply 
of blood in it. This gorging of the membrane of the 
nose with blood causes a great quantity of lymph to 
escape among the cells, and it weakens the resistance 
of the mucous membrane so that the germs on it multiply 
more rapidly. 
Cold drafts may thus cause a cold in a person who 
is in ill health by disturbing the circulation and the dis- 
tribution of the blood ; or perhaps it is better to say that 
cold drafts make a chronic cold worse in this way. It ADENOIDS AND COLDS 
293 
is not advisable, therefore, for a person who is weak or 
half-sick to expose himself suddenly to severe conditions. 
Training the body to endure ordinary exposure. A 
person who suffers from chronic colds needs to build up 
the strength of the body gradually; to accustom the 
vessels of the skin to cold baths gradually so that they 
will act properly instead of throwing him into a chill 
when a blast of cold air is felt; to clear the nasal passages 
and the throat of obstructions; to stop the poisoning of 
the body by decaying intestinal wastes; and, in general, 
by degrees to bring the body back to where it will be 
able to stand ordinary exposure without injury and to 
kill the germs that are causing the cold. Any one 
who is always having colds ought, therefore, to begin 
to build up his health, and if he is wise he will get a 
good physician to guide him in this task. 
Catarrh and bronchitis. Catarrh is a chronic cold 
in the head. Bronchitis is a chronic cold in the bron- 
chial tubes. In both cases the body is kept poisoned 
by the germs that are growing in it. Recently it has 
been discovered that in most cases of these diseases, the 
germs spread from permanent breeding places in the 
tonsils or the nasal sinuses,1 and that treatment is use- 
less until the homes of the germs are broken up. 
There is often no swelling or pain in the infected parts, 
and many persons who are greatly in need of medical 
attention go for years without it. Since infections of 
these kinds are believed to cause many cases of rheuma- 
tism, heart and kidney disease, and other serious ail- 
ments, they should be given prompt medical care. 
aThe nasal sinuses are cavities in the bones that open off from the 
chambers of the nose. 294 
PRIMER OF PHYSIOLOGY 
QUESTIONS 
Describe the nasal passages. What effect has the mucous 
membrane upon the air that passes over it? Name three 
troubles that may occur in the nose, and the remedy for 
them. Describe the throat. What is the soft palate? What 
and where are the Eustachian tubes? 
How many tonsils are there? Where are they? Of what 
kind of tissue are the tonsils composed? What is the cause 
of tonsillitis? What are adenoid growths? 
Give five symptoms of adenoids that show in the face. 
Give other symptoms and effects of adenoids. What is the 
remedy for adenoids and enlarged tonsils ? Mention some bad 
effects of allowing children to wait to outgrow adenoids. 
By what are colds caused ? Distinguish between epidemic 
and chronic colds. Give three ways by which the body resist- 
ance to the germs of colds may be raised. How does the 
practice of taking cold baths protect one from colds ? Explain 
how a cold draft may be injurious. What should a person who 
has chronic colds do to bring his body back into normal con- 
dition ? 
What is catarrh? What is bronchitis? What bad effects 
have they upon the body ? 
SUGGESTIONS TO THE TEACHER 
In every school that is without medical inspection many undis- 
covered cases of adenoids and enlarged tonsils may be found. It is 
a simple matter to learn to recognize the symptoms of these troubles, 
and the teacher can do no greater service than to call the attention 
of parents to the children who are suffering from them. Among the 
arguments that may be advanced in asking that the afflicted children 
be given medical attention are: 
The wasting of the school opportunities of the child; the fixing 
for life of habits of idleness; the danger of injury to the hearing; 
the permanent catarrhal effects ; and the marring of the regularity of 
the teeth and the beauty and symmetry of the face. CHAPTER NINE 
CLOTHING AND THE BODY HEAT 
FIGS. 74 and 75. The object of clothing is to keep up the body heat. 
A man in the cold arctics loses much more heat than 
does a man in the warm tropics. Yet the temperature 
of the human body all over the world is the same. A 
man who is exercising violently produces five or six 
times as much heat as a resting man produces. Yet the 
temperature of the human body during exercise and rest 
is practically the same. Cold-blooded animals become 
warm or cold according to the temperature of their 
surroundings, but the warm-blooded animals, including 
man, keep their heat near a certain point whether the 
weather is hot or cold. In health the temperature of 
the human body varies from 98.8 degrees to about one 
and one half degrees below this point. 
The object of clothing. We take our clothing so much 
as a matter of course, that we often forget that the one 
great purpose in wearing it is to protect us from cold. 
It is true that it protects the body from wounds also, and 
we pay great attention to it because of its effect on our 
appearance; but yet the fact that the inhabitants of the 
295 296 
PRIMER OF PHYSIOLOGY 
frigid regions are clad from head to foot in furs, while 
those who live in the tropics are often very scantily clad, 
shows that man put on clothing, just as he built houses, 
to protect himself from the weather. We ought not, 
therefore, to become so interested in the colors and the 
appearance of our clothing that we forget the real 
reason why it is worn. 
The necessity for a regulator of the body heat. To a 
certain extent we can regulate the heat of the body by 
wearing heavy clothes in winter and lighter clothing 
when the weather is hot. 
Yet we cannot regulate 
the loss of heat from the 
body by clothing alone; 
for the temperature of 
the body must be kept 
constantly at one point, 
while the thermometer 
often runs up and down 
20 or 30 degrees in a 
single day. There must, 
therefore, be some deli- 
cate regulator that will 
govern the loss of heat 
from the body according 
to the changes in the 
temperature of the air. 
This work is done by 
the skin. 
The structure of the skin. The skin is composed of a 
tough outer layer called the epidermis, and of a deeper 
layer of connective tissue called the dermis. The outer 
hair 
oil 
gland 
epidermis 
touch 
corpuscle 
dermis 
sweat 
glatid 
fat 
nerve 
Fig. 76. A section of the skin. CLOTHING AND THE BODY HEAT 
297 
cells of the epidermis are dead and are continually 
scaling off, but the cells in the lower part multiply 
and grow to take the places of those that are lost. 
The dermis contains the nerves of touch and great 
numbers of small blood vessels. Below the dermis is a 
layer of loose connective tissue in which a considerable 
quantity of fat is stored. This layer of fat helps to 
retain the body heat. 
Hair follicles and sweat glands. At certain points the 
epidermis is folded down into deep pockets called hair 
follicles, from the bottom of which the hairs grow. At 
other points sweat glands run down from the outer sur- 
face of the epidermis and lie coiled in the dermis. The 
sweat glands are hollow tubes, the lower ends of which 
are surrounded by lymph. Water from the lymph soaks 
through the walls into the tubes and flows out of the 
mouths of the glands as sweat. 
The body heat regulated by the sweat glands and 
vessels of the skin. The temperature of the body is 
regulated by the sweat glands and the small arteries 
of the skin. During hot weather and when we do 
hard work, the sweat glands assist in cooling the body 
by pouring out sweat on the surface of the skin. The 
evaporation of the sweat cools the skin, just as alcohol 
cools it when allowed to evaporate from it. The ar- 
teries do their part of this work by controlling the 
amount of blood that comes into the skin. When 
the body is exposed to cold, these small arteries 
contract and keep the blood in the warm inner or- 
gans. When the body is heated, they relax and allow 
the blood to come to the surface, where it will be 
cooled. 298 
PRIMER OF PHYSIOLOGY 
The danger of chilling the body. Chilling the body 
disturbs the circulation by driving the blood from the 
skin and congesting the inner parts of the body. This 
makes us especially liable to be attacked by the germs of 
pneumonia, influenza, and colds, — all of them germs that 
are often in the air passages waiting for a favorable op- 
portunity to set up their growth. Wet footwear takes 
the heat out of the feet, thus causing the mucous 
membrane of the air passages and lungs to be gorged 
with the blood that ought to be in the lower limbs, and 
interfering with the germ-killing function of the white 
corpuscles. The wearing of rubbers when they are 
needed to keep the feet dry is a most important precau- 
tion in guarding against colds. 
Danger of overheating the body. Working in a hot, 
moist atmosphere is very exhausting, and it is almost 
impossible to keep up the health during the summer 
months unless we can have air currents to blow away 
the hot air from about the body. Often these can be 
secured by sleeping and working outdoors, by opening 
windows, and by the use of ventilators and electric fans. 
Some persons do not yet realize that from the standpoint 
of health it is as important to keep cool in summer as 
to keep warm in winter. Accordingly, they are willing 
to pay large sums to heat the rooms in which they live 
and work in winter, but are not willing to spend a small 
sum for ventilators and electric fans to be used during 
the heat of the summer. Just as being chilled in winter 
makes us liable to attacks of influenza and pneumonia, so 
overheating in summer lowers our resistance to germs 
and makes us liable to attacks of diarrhea, dysentery, 
and other summer diseases. CLOTHING AND THE BODY HEAT 
299 
Suiting the clothing to the weather. Men who are 
brought into hospitals suffering with sunstroke are often 
found to be wearing heavy 
coats and undershirts, and 
thick woolen trousers. Little 
babies in hot summer weather 
are often covered with “nettle 
rash ” and “ heat rash,” be- 
cause they are dressed in such 
heavy clothing that the skin is 
kept in an overheated condi- 
tion. On the other hand, we 
often see people going without 
wraps and overcoats when 
the weather is so cold that 
the body heat can scarcely 
be kept up with the heaviest 
clothing. What we need to 
remember is that the object 
of dress is to keep the proper 
amount of heat in the body. 
In the spring and fall, especially when the weather 
is changeable, it is important that the weight of the 
clothing correspond to the needs of the body. 
Bathing. One object of bathing is to cleanse the 
body. This we need not discuss. Bathing as it relates 
to health is mainly a question of the temperature of the 
water. Cold baths educate the vessels of the skin so 
that they learn to open and close quickly and thus regu- 
late the body heat properly. The importance of 
having the blood vessels trained to do this is better 
appreciated when we remember that animals in the 
Fig. 77. A Filipina wearing a 
costume that is attractive and well 
suited to a warm climate. The 
material of which the clothing is 
made is thin, and the large sleeves 
and open neck allow the heated air 
to escape from around the body. 300 
PRIMER OF PHYSIOLOGY 
natural state must adapt themselves only to changes in 
the weather, while man often passes in a few seconds 
from an artificially heated building into an outdoor at- 
mosphere that is 30 or 40 degrees colder. When these 
quick changes from warm to cold air are made, the ves- 
sels ought to contract promptly and shut the blood off 
from the skin before too much heat is lost from the body. 
The training of the blood vessels through cold baths 
is of course mainly a work of training the nervous sys- 
tem which controls the vessels, and if a person is weak 
and out of condition, a cold bath may have about the 
same effect on his nervous system that a long race 
would have on the muscles of a person not accustomed 
to taking exercise. In beginning to take cold baths, 
therefore, we must use care. They ought to be begun 
with water that is only cool, the bath should be short, 
and after the bath the skin should be rubbed briskly 
with a rough towel. Colder water may be used as the 
skin becomes accustomed to it, but in no case should 
the water be so cold or the bath so prolonged that the 
reaction fails to come promptly; for when this is the 
case, the blood congests the inner organs and a head- 
ache is the usual result. 
It is the opinion of some physicians that certain 
delicate persons are never able to take cold baths 
without injury ; that baths of this kind are injurious 
to any one who is in poor health or in a nervous con- 
dition, and that only those who are strong and in 
robust health can bear the shock of such a bath with- 
out injury. Others think that any one can train him- 
self to take them with safety. This question we must 
leave to the physicians to decide. CLOTHING AND THE BODY HEAT 
301 
Alcohol and the body heat. In cold weather, taking 
alcohol causes a feeling of warmth, and men often take a 
drink to enable them better to endure cold. The feeling 
of warmth that is given by alcohol is deceptive. We 
feel cold when the blood has been shut off from the 
skin and warm when the hot blood from the inner parts 
Fig. 78. Captain Roald Amundsen, who discovered the South Pole. Because 
alcohol lessens both the endurance of the muscles and the power of the body 
to resist cold, none of it was used on the Amundsen expedition. 
of the body is flowing through the skin. Alcohol 
temporarily paralyzes the arteries of the skin and leaves 
them expanded. This allows the skin to become flushed 
with blood, and causes a sensation of warmth, but at the 
same time it allows the blood to be cooled and the body 
heat to be lost. When we are exposed to cold, the 
vessels ought to be contracted and we ought to feel 
cold. Hence to bring the blood into the skin so that 
the body heat will be lost is an unnatural and unsafe 
thing to do. Persons who use alcohol cannot endure 
cold so well as persons who do not use it, as the ex* 
perience of polar explorers proves. 302 
PRIMER OF PHYSIOLOGY 
QUESTIONS 
What is the temperature of the body? What is the purpose 
of clothing? Why must the body have some means of regu- 
lating its heat? 
Name the two layers of the skin. Describe each. Describe 
a hair follicle. Describe a sweat gland. What is the source 
of the sweat? 
Explain how the heat of the body is regulated. In what 
two ways does chilling the body injure it? How may wet feet 
injure the health? 
What is the effect upon the health of overheating the body ? 
Why are air currents especially important in summer? How 
may they be secured? Discuss the subject of suiting the 
clothing to the weather. At what seasons of the year should 
we be especially careful to change clothing according to the 
weather? 
What do cold baths do for the vessels of the skin ? How 
should one unaccustomed to cold baths begin to take them ? 
Why does taking alcohol give a sensation of warmth? 
What has been the experience of polar explorers in regard to 
the power of drinkers and of abstainers to withstand cold ? 
SUGGESTIONS TO THE TEACHER 
Have the pupils explain why an athlete throws a sweater over his 
shoulders when the game stops for a few minutes. Insist that cloth- 
ing should be adapted to the weather and not to the season. 
Bring out the difference between cold-blooded and warm-blooded 
animals and point out that practically all warm-blooded animals are 
protected by feathers or by hair. CHAPTER TEN 
THE NERVOUS SYSTEM 
The work of the nervous system has always been a 
mystery to mankind. The ancient Greeks thought that 
the brain distilled 
some kind of vital 
spirit, or essence, 
which flowed out 
through the body in 
the form of a gas. 
If the brain were in- 
jured so that the 
supply of this spirit 
was cut off, or if the 
body were deeply 
wounded so that the 
vital spirit escaped, 
life came to an end. 
Today we know a 
great deal more than 
the Greeks knew 
about the nervous 
system, but our 
knowledge of it is yet 
far from complete. 
We know enough, 
however, to help us 
greatly in the care 
of the body, and in 
this chapter we shall take up some of the facts concern- 
ing the nervous system that it is most important for us 
to understand. 
Fig. 79. The nervous system. 
303 304 
PRIMER OF PHYSIOLOGY 
The parts of the nervous system. The nervous sys- 
tem is composed mainly of the brain, the spmal cord, 
and forty-three pairs of nerves that run out from the 
brain and the spinal cord to all parts of the body. 
It includes also many little masses of gray tissue, called 
ganglia (singular, ganglion), that are found among the 
inner organs of the body, and a great network of nerve 
fibers that run among these organs. 
The function of the nervous system. The first func- 
tion of the nervous system is to control all the organs and 
parts of the body. If the heart should beat fast when 
we lie down to rest and slow when we run; if the sweat 
glands should pour out water on the skin when we are 
already freezing and stop work on the hot days of sum- 
mer; if the muscles moved how and when they 
pleased, so that they jerked the body aimlessly about; 
if all the organs worked without system or plan, so that 
each part of the body carried on its activities without 
regard to the rest of the body, we should not have a 
working machine at all, but only a collection of organs 
and parts. A ruler must, therefore, be set over the 
whole body to keep all the parts working together 
properly. This ruler is the nervous system. 
The second function of the nervous system is to act as 
the organ of the mind. This function we shall discuss 
when we take up the study of the brain. 
The nervous system composed of cells and fibers. The 
nervous system is made up of nerve cells and of nerve 
fibers. The nerve cells are larger than most of the body 
cells, and have a gray color. Most of the nerve cells are 
found in the brain and spinal cord, but a few of them are 
found in the ganglia, which are little balls of nerve cells. THE NERVOUS SYSTEM 
305 
The nerve fibers connect the nerve cells with the 
other parts of the body. They have a glistening white 
color, but each fiber has a gray central part which 
carries messages to and from the spinal cord and 
brain. This gray core of the fiber is a 
branch of a nerve cell, and we may 
think of the nerve fibers as long 
branches of the cells which run out to 
all parts of the body. The white nerves 
that we see in the body of an animal 
are bundles of nerve fibers. The finest 
nerves contain but a few fibers, and can 
be seen only with a microscope. The 
sciatic nerve, which runs to the leg, is 
the largest nerve in the human body. 
This is a flattened cord three fourths of 
an inch across. 
Motor and sensory nerve fibers. 
Some of the nerve fibers carry mes- 
sages from the brain and spinal cord 
that cause our muscles to move. These 
are called motor fibers. Other fibers 
carry messages from the skin, the eye, 
the ear, and other parts of the body to 
the brain. These messages cause us to feel, to see, to 
hear, and to understand the condition of all the parts 
of the body. They cause sensations in the brain, and 
the fibers over which they pass to reach the brain are 
called sensory fibers. 
The brain. The brain is a mass of very soft tissue 
weighing about fifty ounces and filling the cavity of the 
cranium (Fig. 21). It has three principal divisions, the 
Fig. 80. A nerve cell 
and nerve fiber. At the 
lower end the attach- 
ment of the fiber to the 
muscle cells is shown. 306 
PRIMER OF PHYSIOLOGY 
cerebrum, the cerebellum, and the medulla oblongata. 
A general idea of the appearance of the different parts 
of the brain may be gained from Figure 81. 
cerebrum 
convolutions 
medulla oblongata 
cerebellum 
FlG. 8i. The brain seen from the side, showing the three principal divisions. 
The cerebrum. The cerebrum makes up more than 
three fourths of the entire brain. It is divided by a deep 
groove into right and left hemispheres. The outside 
layer of the cerebrum is composed of nerve cells, and 
therefore has a gray color. To make more room for 
these cells the whole surface of the cerebrum is thrown 
into folds, or wrinkles, that are called cojivolutions. 
From the cells of the cerebrum a great network of 
fibers runs in all directions through the brain, and 
connects all its different parts with each other. Other 
fibers run down through the medulla into the spinal 
cord and connect the cerebrum with all parts of the 
body. Most of the motor fibers from the cerebrum are 
crossed in the medulla, so that the right side of the 
cerebrum is connected with the muscles of the left side 
of the body, and the left side of the cerebrum is con- 
nected with the muscles of the right side of the body. 
The function of the cerebrum. The gray outer layer 
of the cerebrum is the seat of all intelligence. Without THE NERVOUS SYSTEM 
307 
it all sensations of light, sound, taste, smell, touch, heat, 
and hunger are lost. When it is removed, all power of 
moving the voluntary muscles is gone. The cerebrum, 
therefore, is the part of the brain that thinks and feels. 
It is the part that causes us to remember and to know, to 
love and to hate, to be glad and to be sad. The cere- 
brum decides what we shall do; it sends out the mes- 
sages to the muscles when we wish to move; and it 
governs the whole body. With- 
out its cerebrum an animal can 
live, but all its intelligence is 
gone. It still breathes and its 
heart continues to beat, but it is 
only a machine, knowing nothing 
of its own needs and of the 
world about it. 
The cerebellum. The cerebel- 
lum lies under the back lobes of 
the cerebrum. Its function is to 
cause all the muscles to keep the 
proper tension, and to assist in 
governing the muscles of locomotion. In walking, more 
than two hundred muscles are used in holding the body 
upright and in moving the different parts that are brought 
into action. Each of these muscles must contract 
with exactly the right force and at exactly the right time, 
or they will work against each other and the right 
movements will not be made. When the cerebellum is 
injured, all the muscles are weakened and relaxed, and 
the person loses control of the muscles that support the 
body and move the legs. This causes him to stagger 
and reel like a drunken man. 
Fig. 82. The cerebrum seen 
from above, showing the hemi- 
spheres. 308 
PRIMER OF PHYSIOLOGY 
The medulla and the spinal cord. The spinal cord is 
about half an inch in diameter and eighteen inches long. 
Without the roots of the nerves that rise from it, it 
weighs about an ounce. It lies in the canal in the center 
of the spinal column and is securely protected by the 
bones about it. The enlarged upper end of the cord 
is the medulla. 
• Both the spinal cord and the medulla are composed 
in large part of fibers that connect the brain with the 
different body parts. Some of these are sensory fibers, 
through which messages from the body are passed up 
to the brain. Others are motor fibers, over which 
commands from the brain pass down on their way to 
the different parts of the body. In addition, the medulla 
contains the centers which govern the heart and lungs. 
When the cerebrum of an animal is removed, the intel- 
ligence is lost; when the cerebellum is injured, control 
of the muscles is lost; but when the medulla is injured, 
life at once ceases, because the beating of the heart 
and the breathing stop. 
Reflex action. Much of the governing of the body 
by the nervous system is done without thought. The 
messages, or nerve impulses, pass through the sensory 
nerve fibers into the nerve cells, pass on through the 
branches of these cells into other cells that are touching 
them, and come out again by way of a motor nerve. 
An action that is caused in this way is called a reflex 
action, and it can best be explained by an example. 
Cross your legs, and strike yourself just below the 
kneecap with the edge of your hand. If you strike the 
right place, you will start messages to the spinal cord. 
These, without any thought whatsoever on your part, will THE NERVOUS SYSTEM 
309 
pass into the motor nerves and down into the muscles of 
the leg. The muscles of the leg will then contract and 
cause the foot to jerk. A reflex action is an involuntary 
action caused by an impulse that 
starts in a sensory nerve. It is 
very different from the voluntary 
actions that are caused by im- 
pulses which start in the cere- 
brum and pass out to the muscles 
when we wish to move some part 
of the body. Practically all the 
governing of the internal organs- 
of the body is carried on by re- 
flexes. 
Reflexes acquired through 
practice. The reflexes that we 
have been discussing are natural 
reflexes ; we are born with them. 
There is another set of reflexes 
that comes to us through prac- 
tice. The skilled swimmer does 
not think how he shall move his 
arms and legs; in boxing, the hands move without 
thought and almost faster than the eye can follow; 
the telegrapher does not think about the combination 
of dots and dashes that spell out a word, but reads 
the message he is sending, and his hand does the rest. 
In the same way, all of us every day do a great part 
of our work without thought. We walk without giving 
attention to the muscles and parts which we must 
move; we open our mouths to take in food without 
thinking; we chew our food without noticing that we 
Fig. 83. The ball starts from 
the hand and comes back to it 
again. The impulse that causes 
a reflex action starts from the 
outer end of a sensory nerve 
and comes back to the muscle 
or gland that is thrown into 
action. It does not start from 
the brain. 310 
PRIMER OF PHYSIOLOGY 
are chewing; we write without conscious thought as 
to the shape of the letters. All these things we 
have repeated so often that we have learned to do 
them without thought. 
Acquired reflexes and education. A very important 
part of education consists in establishing the right re- 
flexes, so that without thought we shall do the more 
common things of life properly. A young person who 
is learning to write ought to learn to hold his pen in the 
right way and to shape the letters correctly, so that the 
right reflexes will be formed and the writing question 
settled for life. He ought to learn to group his words 
properly and to give the right inflection in reading, so 
that these matters will attend to themselves thereafter. 
He ought to take great care to say “ please ” and “ thank 
you ”; to modulate his voice so that it will not become 
loud and strident when he is talking eagerly; to take 
off his hat and to rise to his feet when he should do 
so; and to do all the other things that go to make 
up pleasant manners; for no one will ever have good 
manners who has not established reflexes that will make 
him able to do what he ought to do naturally and with- 
out thought of his actions. 
When you are learning to do anything, the great 
thing is to do it right, so that you will form a reflex 
action of the right kind. Then as long as you live 
the part of your conduct and work that depends on 
this reflex will take care of itself and you will be 
free to expend your energy on the new problems that 
arise day by day. The object of the training that 
you are receiving at home and in school is to make 
for you a set of tools with which to carry on the work THE NERVOUS SYSTEM 
311 
of your life. If you wish to be a good workman, you 
must, first of all, manufacture for yourself a good set 
of tools. 
Habits. Habits are really reflexes that we form by 
repeating acts, and just as physical habits can be formed, 
so can moral habits, and habits of the mind, be formed. 
All kinds of habits are formed most readily in youth, 
and it is seldom that long-established habits are broken 
after the age of twenty-five or thirty. Indeed, it is dif- 
ficult at any time of life to break a habit that has once 
been thoroughly established. It is because this is true 
that young people are so constantly urged to form habits 
of honesty, neatness, accuracy, and cleanliness. An 
investigation at Harvard University has shown that the 
students who do high-grade work in the schools of law, 
medicine, and engineering are students who did their 
work well before entering these schools; that it makes 
little difference what subjects they have studied previ- 
ously, but that it makes a great deal of difference whether 
they have formed the habit of learning their lessons 
regularly and thoroughly, or of going through them in a 
lazy and careless way. The trifler in the lower grades 
of school is usually a trifler still in the high school, and 
very few high-school drones ever become capable and 
industrious college students. 
Just what it is that makes the nervous system want to 
keep on doing things in the same way, we shall not 
attempt to explain, but it is a well-known fact that what 
a man does in youth determines very largely what kind 
of person he will be in later life. If in youth he forms 
habits of dishonesty and laziness, he is almost certain 
to develop into an unreliable and unsuccessful man. 312 
PRIMER OF PHYSIOLOGY 
If in youth he forms habits of honesty, industry, and 
promptness, he will probably become a trusted and a 
successful man. Rip Van Winkle was always intending 
to stop drinking, but when a glass was offered him, he 
would say: “ We won’t count this time ”; so the time to 
begin his new life never came. There are many persons 
who have good intentions and are meaning to get down 
to work in the future, but their habits keep them loiter- 
ing on in the same old ways. The importance, therefore, 
of forming correct habits in youth can hardly be over- 
estimated. 
QUESTIONS 
Name the principal parts of the nervous system. Give two 
functions of the nervous system. Of what is the nervous system 
composed? Describe a nerve fiber. What are ganglia? What 
are motor nerve fibers ? sensory nerve fibers ? 
Describe the brain. Describe the cerebrum. How is the 
cerebrum connected with the other parts of the brain? with all 
the parts of the body? What is the function of the cerebrum? 
What part of the cerebrum is the seat of intelligence? Can 
an animal live if its cerebrum is removed? 
Where is the cerebellum? What is its function? What effect 
upon a person has an injury to the cerebellum? 
Describe the spinal cord and the medulla. Why does injury 
to the medulla cause death? 
What is a reflex action? Give an example. Describe the 
course of the impulse in a reflex action. Describe the course 
of the impulse in a voluntary action. What is an acquired re- 
flex? How may right reflexes be established? Why is it im- 
portant to establish this kind of reflexes ? 
What is a habit? Why is it so important to establish right 
habits in youth? What did the investigation at Harvard 
University show in regard to the foundation of good scholarship? THE NERVOUS SYSTEM 
313 
SUGGESTIONS TO THE TEACHER 
Secure if possible prepared microscopic mounts that will show 
nerve cells, nerve fibers, and the cross-section of a nerve, and have 
the pupils examine them. For demonstrating the gross structure 
of the brain, the brain of a sheep is very commonly used. If a 
sheep’s head is not easily available, the head of a cat, rabbit, or fowl 
may be used. A pair of bone forceps will be needed for breaking 
away the skull, and after removal the brain should be hardened in 
alcohol or five per cent solution of formalin. 
Make clear that a reflex action is always involuntary, but may or 
may not be unconscious. A good example of an unconscious reflex 
is the expansion and contraction of the pupil that follows shading 
the eye and then exposing it to the light. With the aid of a mirror 
the pupil can observe this in his own eye by facing the light, cover- 
ing his eye with his hand, and then removing the hand. If no 
mirror is at hand, the experiment may easily be performed on an- 
other person. To a great extent the internal organs are governed 
by reflexes of this class. The winking or dodging reflex may be 
used to illustrate conscious reflexes. 
Emphasize the physical aspects of habit. Bring out the fact that 
in the doing of our daily work and the living of our daily lives it is 
inevitable that we shall form either correct habits or wrong habits. 
The late Professor James’ discussion of habit, which may be found 
in either his Talks to Teachers or his Textbook of Psychology (pub- 
lished by Henry Holt and Co., New York), is a masterly and inspir- 
ing piece of writing. Every teacher may with profit read it himself, 
and selections from it may be read to the class. 
In teaching this and the following chapter, the teacher should 
bear in mind the importance of fixing quiet, orderly habits of 
mental work in order that there may be no waste of nervous energy 
through excitement and overeagerness. Some teachers who are 
very successful in imparting information fatigue their pupils unduly 
through the tense, nervous atmosphere of the school. This is com- 
ing to be recognized as an important point in school hygiene. CHAPTER ELEVEN 
THE CARE OF THE NERVOUS SYSTEM 
Fig. 84. There is no truth in the idea that a person can have too much 
natural sleep. 
Suppose that you decide to raise your hand. The 
hand comes up. Can you explain exactly what made it 
rise ? It is in reality a very complicated action, and to 
make sure that you understand it we will go through the 
different steps in it with you. 
First of all, you decided to raise your hand. This was 
an act of the mind. Then nerve impulses, whatever 
they may be, were started out from the brain. These 
impulses traveled down through the medulla and spinal 
cord, passed out into the nerves of the arm, and finally 
entered the muscle cells. This caused the muscle cells 
to contract and lift the arm. The muscle did the work, 
but the nervous system decided what was to be done and 
caused the muscle to do it. 
In all our other activities we find that the nervous 
system plays a guiding and controlling part. The regu- 
lation of the body heat, the secretion of the digestive 
314 THE CARE OF THE NERVOUS SYSTEM 
315 
juices ; the excretion of the wastes; all these processes, 
as well as every movement that we make, are under the 
control of the nervous system. We must, therefore, keep 
the nervous system in health; for when it goes wrong 
in its work, the whole body suffers. Fortunately for us, 
our nervous systems are splendidly built, and on the 
whole they do their work faithfully and well. There 
are, however, certain points in the care of them in which 
many persons fail, and we ought to have an understand- 
ing of these points. 
Sleep necessary for the nervous system. The cells of 
the nervous system must have sleep to build themselves 
up for further work, and so far as we know they are the 
only part of the body that needs sleep. The amount 
of sleep needed varies greatly in different persons 
and in persons of different ages. A little baby may 
sleep as much as twenty-two out of the twenty-four 
hours. At six months of age he sleeps about sixteen 
hours. At seven years of age a child should sleep eleven 
or twelve hours; at ten or twelve years of age, at least 
ten hours. Older persons should take the amount of 
sleep that they find best for them. Occasionally a per- 
son is found who keeps in good health on four, five, or 
six hours of sleep. Other persons must have eleven or 
twelve hours. Each one should go to bed early enough 
not to feel sleepy when getting-up time comes; for there 
is no truth in the idea that one can have too much 
healthy sleep.1 
Are you still tired and sleepy when you waken in 
1 Illness and poisons absorbed from the intestines cause drowsiness. 
When a person is sleepy from one of these causes, the condition is, of 
course, an unnatural one. 316 
PRIMER OF PHYSIOLOGY 
the morning ? Are you pale and languid and do you drag 
yourself through your work ? If you are, it may be 
because you are cutting your sleep short; for there are 
thousands of people who are starving for sleep as truly 
as other people are starving for food and fresh air. If 
you have fallen into a habit of staying up late in the 
Figs. 85 and 86. A change for a time to a different kind of occupation is rest- 
ful to the nervous system. 
evenings, break this habit and go to bed early. A 
runner or a baseball team that has been losing sleep 
has not the slightest chance of winning from others of 
equal ability who have had a sufficient amount of it. 
This is because the nervous system, when it lacks sleep, 
is out of condition and cannot control the muscles as 
it should. 
Rest necessary to the health of the nervous system. 
A great amount of nervous energy is required to drive 
the more than five hundred muscles of the body, and 
when we study or do other brain work, it is the nervous 
system that is called into action. In either physical or THE CARE OF THE NER VO US SYSTEM 
317 
mental work, therefore, we tire the nervous system, and 
we ought not to continue either until our cells are poi- 
soned with the “fatigue toxins ” that appear in the body 
in cases of exhaustion. 
Factory workers who are forced to speed themselves 
up to machines, and little children in schools where the 
recitation periods and the school days are too long, 
suffer from fatigue and cannot do their best work. 
Many earnest, ambitious individuals who are trying 
to do the very best work of which they are capable, 
injure themselves and lower their working power by 
keeping their nervous systems exhausted.1 In general, 
it has been found best to work hard during regular 
working hours, and then to have rest periods when 
something entirely different is done. In schools there 
should, therefore, be rest and play periods for young 
children, and older persons ought to work certain hours 
every day and then for a time have a different kind of 
occupation. 
Fresh air helpful in resting the nervous system. A 
nerve fiber from a frog will carry impulses all day 
without fatigue if it is exposed to the air so that it 
can take in the oxygen that it needs. If the supply of 
oxygen be cut off from it, however, it soon becomes ex- 
hausted. Undoubtedly children in open-air schools can 
do more work without becoming tired than can children 
in indoor schools, and it is the belief of those who sleep 
1 In some factories it has been found that the workmen can accomplish 
more when they work eight hours than when they work ten hours, be- 
cause when they work the longer hours they are always tired and never in 
good condition. The number of hours that is best for a working day 
must, of course, vary with the kind of work and with the kind of people 
who are doing the work. 318 
PRIMER OF PHYSIOLOGY 
in the open air that they need about an hour’s less sleep 
than they require if they sleep indoors. These facts in- 
dicate that fresh air is an aid in preventing exhaustion, 
and that tired nerve cells are more quickly rested and 
built up when the body is given plenty of outdoor air. 
A peaceful mind necessary for health. In our study 
of the nervous system we must always keep in mind 
FIG. 87. Both the child’s pleasure at seeing the toy and the man’s pleasure at 
seeing the child’s happiness affect the mind, and through the mind affect the 
body. 
that it has the double function of governing the body 
and of acting as the organ of the mind. It is perhaps 
economical to have these two different kinds of work 
done by the same system, but this plan has its drawbacks 
as well as its advantages; for the condition of the 
mind greatly affects and sometimes interferes with the 
proper regulation of the body. 
Good news or bad news may greatly change the beat- 
ing of the heart. A toy that pleases a child will cause 
his whole body to tingle with pleasure, and will cause 
impulses to pass out to his muscles that will make him THE CARE OF THE NERVOUS SYSTEM 
319 
laugh and clap his hands. Food that is pleasing to the 
taste, or even the sight or smell of food, will cause the 
“ mouth to water,” which is another way of saying that 
it causes the digestive juice to flow from the salivary 
glands. Experiments on a dog have shown that the 
sight and smell of food, even though the food does not 
reach the stomach at all, causes an abundant flow of the 
digestive juices in the stomach; while in a dog that was 
made angry by having a cat placed near it when it was 
eating, the flow of the juice in the stomach was inter- 
fered with for two whole days. All these facts show 
that anger, sorrow, and worry interfere with the proper 
action of the body; that the mind greatly affects the 
body; and that a cheerful, quiet, hopeful mind is neces- 
sary for health. 
At the same time, we must realize that sickness is a 
real thing, and that when it comes upon us we cannot 
depend upon the mind alone to restore us to health. 
When a child has diphtheria, only antitoxin will save its 
heart from being poisoned, and when tuberculosis attacks 
the lungs, good food, fresh air, and rest, as well as 
cheerfulness and hope, are needed if the body is to 
make a winning fight against the germs. When the 
kidneys have been poisoned by scarlet fever or by the 
use of alcoholic drinks, nothing that we can think about 
them will make them able to throw the wastes out of 
the body as a pair of sound kidneys are able to do. 
The mind cannot take poisons out of the body; it can- 
not kill germs that get into the body. These things 
the body must do for itself, and all that the mind and 
the nervous system can do is to help to keep each or- 
gan of the body at work at its particular task. 320 
PRIMER OF PHYSIOLOGY 
Nevertheless, it is true that the nervous system rules 
the whole body; that when the nervous system goes 
wrong, the whole body goes wrong; and that just as 
food, fresh air, exercise, and rest are necessary to the 
health of the body, so a peaceful, hopeful mind is 
necessary in order that the nervous system may remain 
in health and regulate all the body parts properly. 
QUESTIONS 
What part of the body needs sleep? How much sleep 
should a baby have ? a child seven years old ? a child twelve 
years old? an adult? 
Why is rest necessary for the nervous system ? Under what 
conditions of work and rest can a person do the best and 
most work? Give three facts indicating that open-air life pre- 
vents exhaustion of the nerve cells. 
What is the effect of joy, hope, and other pleasant emotions 
on the nervous system? What is the effect of anger, sorrow, 
or worry ? What mental state is necessary to the health of the 
body? Mention some experiments with animals that prove 
this. Can the mind take poison out of the body? Can it kill 
germs? How can the mind help the body to do these things? 
SUGGESTIONS TO THE TEACHER 
Emphasize the fact that nerve cells have the same needs as the 
other cells and that any trouble in other parts of the body is bound 
to damage the nervous system. Dr. Thomas D. Wood of Columbia 
University estimates that “ 15,000,000 out of the 20,000,000 children 
in the schools of the United States need attention for physical de- 
fects which are partially or completely remediable.” Insist on the 
evil effects of pain and ill-health on the nervous system, and use 
this as an argument for avoiding infections and for giving attention 
to adenoids, decayed teeth, painful feet, defective eyes, and other 
physical defects. CHAPTER TWELVE 
THE EYE 
Many of the messages which travel up the nerves to 
the brain are started within the body itself, and cause 
sensations that tell us about the condition of the body. 
Examples of sensations of this kind are sleepiness, 
fatigue, weakness, faintness, hunger, thirst, and nausea. 
Others of the messages that come to the brain are 
started in the nerves by things that are outside the body, 
and these messages bring us information about the out- 
side world. The nerves that carry these messages are 
the nerves of sight, hearing, touch, taste, and smell. 
Seeing, hearing, touching, tasting, and smelling are the 
five special senses, and the eye, the ear, the nose, the 
mucous membrane of the mouth, and the skin are the 
special sense organs. 
The brain dependent on the sense organs for informa- 
tion. Through the special sense organs we learn all that 
we know of the world about us, and when anything in- 
terferes with the proper working of these organs, much 
information that ought to come to the brain fails to 
reach it. Many children who are thought to be stupid 
are dull, not because they have slow brains, but because 
their eyes and their ears are not quick in gathering the 
information that is necessary to make them intelligent. 
We must learn to care for our sense organs, especially 
for our eyes and ears, for without them the brain sits in 
idleness, and is no more certain of what is the right thing 
to be done than is the commander of an army whose 
scouts bring him no news of the enemy’s movements. 
The nerves in the eye stimulated by light. Light is 
waves in the ether which fills all space, and the eye 
321 322 
PRIMER OF PHYSIOLOGY 
is an instrument so constructed that when light enters 
it the nerves of sight are stimulated and messages are 
started to the brain. These 
messages give us a series of 
pictures of the world about us, 
from which we learn about 
the color and the form of ob- 
jects, about their movements 
and their nearness to us. From 
these pictures much of our 
knowledge comes. Much of 
the pleasure also that we have 
in the world comes from them ; 
for just as music starts messages from the ear that give 
pleasure to the mind, so beautiful objects start messages 
from the eye that are pleasing to us. Years ago, a great 
man of science suggested that we should have concerts of 
beautiful colors for the eyes as well as concerts of music 
for the ears. Such concerts have already been attempted. 
The protection of the eyes. The eyes are protected 
from blows by the deep sockets in which they lie, and 
by cushions of fat on which they rest and turn. They 
are protected from dust and sweat, and screened from 
light, by the eyelids, the eyelashes, and the eyebrows. 
In the outer corner of each of the upper eyelids is a 
small gland which secretes the tears. These flow across 
the eyes to the inner corners, and run down a little duct 
into the nose. In their passage across the eye, the tears 
wash away dust and germs. In the eyelids are glands, 
very similar to the glands that oil the hair, which pour 
out oil along the edges of the eyelids. Sometimes these 
glands become diseased, and the secretion from them 
-tear duct 
tear 
gland 
-nasal cavity 
Fig. 88. The tear gland and the 
duct that carries the tears to the 
nose. THE EYE 
323 
dries and forms scales around the roots of the eyelashes. 
The trouble in cases of this kind is that germs are grow- 
ing in the gland. Dropping a solution of boracic acid 
(as much as will dissolve in water) into the eyes will 
help to kill the germs. 
The muscles of the eye. The eye is moved about by 
six muscles. The back ends of these muscles are at- 
tached to the eye sockets. 
The front ends are at- 
tached to the ball of the 
eye. These muscles can 
turn the eye in, out, up, 
or down. It is not nec- 
essary always to turn the 
head toward an object 
which we wish to see ; for the eye muscles can turn 
the eye toward it while the head is at rest. 
In some persons from birth the sight of one eye is 
better than that of the other eye. Such a person may 
fall into the habit of using only his good eye, and the 
muscles of the weak eye will not turn it toward the 
objects he looks at. A person whose eyes behave in this 
way is said to squint, or to be cross-eyed. Usually the 
trouble can be remedied if it is taken in time, but if it is 
not attended to in very early life the sight of the defec- 
tive eye will be lost. A little child with this trouble 
should, therefore, have proper treatment at the earliest 
possible date. 
The structure of the eye. The eye has a tough, white 
outer coat called the sclerotic coat; a dark middle coat 
called the choroid coat; and lining the back two thirds 
of the eye, a delicate inner coat called the retina. The 
optic nerve 
Fig. 89. The muscles that move the eye. 324 
PRIMER OF PHYSIOLOGY 
front part of the sclerotic coat, which is called the 
cornea, is transparent like glass, and we look out, or 
rather the light comes in, through a little window that 
is like a small round watch crystal on the front of the eye. 
sclerotic coat 
vitreous 
humor 
cornea 
aqueous 
humor 
retina - 
choroid coat 
pupil- 
■lens 
optic nerve 
iris 
ligament 
muscles 
Fig. 90. A diagram showing the structure of the eye. 
Inside the eye is found a circular, clear structure 
called the lens, which is fastened by ligaments to the 
choroid coat. The lens and the ligaments that sup- 
port it divide the eye into a small front chamber and a 
large back chamber. The front chamber is filled with 
a watery liquid, called the aqueous humor. The back 
chamber contains a clear jelly-like substance called the 
vitreous humor. The nerves of sight enter at the back 
of the eye and spread out in the retina. The light 
reaches these nerves and starts messages in them by 
passing in through the cornea, the aqueous humor, the THE EYE 
325 
lens, and the vitreous humor, and striking against the 
retina. 
The iris and the pupil. The front part of the choroid 
coat is called the iris. This shows through the clear 
cornea, and the person is black-eyed, 
brown-eyed, or blue-eyed according 
to the color of his iris. In the center 
of the iris is a circular opening called 
the pupil. Through this the light 
passes into the eye. Muscles in the 
iris regulate the size of the pupil ac- 
cording to the brightness of the light, 
Examine your own eyes after being 
in a bright light and again after 
being in a weak light, and you will 
have no trouble in seeing the differ- 
ence in the size of the pupils. 
The image formed by the lens on 
the retina. If you were to focus a 
camera on a group of objects, as for example a house 
with trees surrounding it, and then look at the ground 
glass in the back of the camera, you would see an image 
of the scene that lies before the camera. The image 
w.ould be upside down, and the right and left sides 
would be reversed, but the house and the trees would 
be there, each with its own colors, and each in the right 
position in the group. The lens in the front of the 
camera forms this image by gathering up all the light 
that comes into the camera from each of the objects, 
and bringing the rays together so as to form a picture of 
all the objects. 
In the same way, the lens of the eye forms on the 
Fig. 91. The iris and 
the pupil. 326 
PRIMER OF PHYSIOLOGY 
retina images of the objects that we see. In the eye, 
as in the camera, the images are upside down, but they 
are there in their proper col- 
ors, and the different objects 
have the right sizes and the 
right positions in regard to 
each other. This picture of 
whatever we are looking at 
starts impulses in the nerves 
of sight to the brain, and 
when these messages are re- 
ceived by the brain, we form 
judgments about the size, 
color, and form of the ob- 
jects, and say that we see 
the objects. By means of 
the images in the eyes we 
can judge also of the dis- 
tances of objects from us, of 
their movements, and of their 
smoothness or roughness. 
The shape of the lens 
changed in looking at far and 
near objects. In looking at 
a near object the lens of the eye must be rounded up, 
and in looking at a far object it must be flattened. This 
rounding and flattening of the lens is done by little mus- 
cles in the eye which loosen and tighten the ligament 
that supports the lens. If you should fill a small sack 
with water and then pull on the ends of the sack, you 
would flatten it; and if you should then stop pulling 
on the ends of the sack, the sack would of itself round 
FlG. 92. The lens in the camera 
forms inverted images on the ground 
glass in the back of the camera. THE EYE 
327 
up. So in the eye, when the ligament is loosened, the 
lens becomes rounder. This change in the shape of 
the lens is called the accommodation of the eye, be- 
cause by it the eye is accommodated to the nearness 
or farness of the object. 
Near-sightedness, far-sightedness, and astigmatism. In 
a camera, if you move the lens too far forward or back- 
ward, the image becomes blurred. So in the eye the 
image will not be clear and the vision will not be dis- 
tinct, unless the lens is the right distance from the retina. 
The eyes of some persons are too long from front to 
back. In such eyes the lens is too far from the retina 
and the image is indistinct. These persons see near 
objects better than far objects, and they are therefore 
said to be near-sighted. Any one who bends over his 
book in reading, or who holds his book less than twelve 
inches from his eyes, is near-sighted. 
The far-sighted eye, on the other hand, is too short 
from front to back, and the lens is too close to the 
retina.1 Persons with eyes of this kind see distant ob- 
jects best, and they are said, therefore, to be far-sighted. 
In other eyes, the curvature of the cornea is not the 
same in all its parts; that is, some parts of it are flatter 
than other parts. Rays of light that pass through this 
uneven cornea cannot all be brought to a focus at one 
point, and a clear image is impossible in such an eye. 
This trouble is called astigmatism. It is a very com- 
mon defect in the eye and may be found alone, or along 
with either near-sightedness or far-sightedness. 
Necessity for a clear image in the eye. If a sharp, 
1 In some cases of near-sightedness and far-sightedness che trouble may 
be in the shape or the refracting power of the lens. 328 
PRIMER OF PHYSIOLOGY 
clear image is not formed on the retina of the eye, seri- 
ous troubles follow. The muscles in the eye keep pull- 
ing and working to try to change the shape of the lens 
so that the vision will be clear; in reading it is a strain 
on the attention to tell what letters are in the words, 
and, in general, it makes all work that requires close 
attention more difficult. This overworks and deranges 
the nervous system, and soon the health of the whole 
Figs. 93 and 94. There are 5,000,000 school children in the United States 
who need glasses. 
body is injured. Two of the most common symptoms 
of eyestrain are headache and trouble with the digestion, 
often accompanied by dizziness and vomiting. 
The importance of spectacles. It is often said that 
the great amount of close work that people now do 
injures their eyes, and it is insisted that the eyes of 
school children in particular are damaged by the work 
that they are required to do. There is doubtless some 
truth in this statement, but it is also true that many eyes 
are naturally defective. Examination of the eyes of the 
Indians who come direct from the plains to Hampton 
Normal School, in Virginia, shows that 34.6 per cent THE EYE 
329 
of them are in need of glasses to improve their vision 
or to relieve eyestrain. 
It is estimated that there are 5,000,000 school children 
in the United States who have defective eyes. Nothing 
can be done for these eyes except to put glasses before 
CUFF 
P n T F 3 
O III D 3 
Fig. 95. You should be able to read the upper line at a distance of 30 feet, 
and the two lower lines at a distance of 20 feet. 
them that will cause clear images to fall upon the 
retinas. We shall not attempt to explain the kinds of 
glasses that are used to correct the different kinds of 
eye trouble, but it is an easy matter for a good oculist 
to select the kind of lens that each eye needs. Test 
your vision with the letters given on this page, and if 
you have reason to believe that you need glasses, try to 
get them ; for if glasses are put on in time, many cases 330 
PRIMER OF PHYSIOLOGY 
of astigmatism and near-sightedness will be outgrown, 
while if these troubles are neglected, the shape of the 
eye may be so spoiled that the person will be compelled 
to wear glasses all his life. 
The eyes injured by disease germs. In measles, 
scarlet fever, and smallpox, the germs grow in the eyes. 
During the progress of these diseases the eyes should 
be rested and shielded from a bright light, and when 
the eyes have been severely attacked, they should not 
be used until recovery is complete. “ Pink eye ” is a 
highly infectious disease that often leaves the eyes red 
and inflamed for life. It is spread by germs that are 
passed from one person to another, and a child with 
“ pink eye ” ought not to be in school. Trachoma, or 
“ granulated lids,” is another germ disease of the eyes 
that is greatly to be feared. It is infectious, and it is 
unsafe to be around a person who is suffering from it. 
Do not wash your eyes in a public wash basin; do not 
touch a public towel; do not touch your eyes with dirty 
hands; and do not touch the hands, the pencil, or the 
books of any one who has sore eyes. 
Importance of a good light while working. To read 
or to work by a dim light is very injurious to the eyes. 
Too bright a light also is injurious, especially if one 
faces it, and a flickering light of any kind is bad. In 
writing one ought to sit so that the light comes over the 
left shoulder; for then the shadow of the hand will not 
interfere with the work. Facing a window in the day- 
time, or a lamp at night, is hard on the eyes. Reading 
on into the twilight is a great strain on the eyesight, 
and one ought not to seat himself carelessly too far 
from the light when doing close work at night. THE EYE 
331 
One difficulty when the light is too dim is that the 
work is kept so close to the eyes that there is a great 
strain on the muscles that turn the eyes inward ; for the 
closer an object is to the eyes, the more must the eyes 
be turned inward to focus both of them on it at the 
same time. Keeping the work close to the eyes is 
FlG. 96. A good light while reading is important. 
especially injurious in the case of little children; for 
their eyes are soft and easily pulled out of shape, and 
the muscles tugging at the eyes to turn them inward 
spoil the shape of the globe of the eye and cause astig- 
matism. To prevent this, school books for young chil- 
dren ought to be printed in type large enough so that 
the children will not have to keep the books close to 
their eyes while studying, and schoolrooms should be 
well lighted. The rule in erecting modern school build- 
ings is to allow from one sixth to one fourth as much 
space for windows as there is floor space in the room. 
Ribbed glass used in the upper sashes assists very 
greatly in spreading the light evenly over the room. 332 
PRIMER OF PHYSIOLOGY 
Resting the eyes helpful and overtaxing them injuri- 
ous. When we have been reading or doing other close 
work for some time, it benefits the eyes greatly to stop 
for a few moments and look at a distant object, or to 
gaze into the distance without looking at anything in 
particular. Reading on a moving train or a street car 
quickly tires the eyes, because the distance between 
the book and the eye is constantly changing, and the 
muscles in the eye are kept busy changing the shape 
of the lens. Reading while lying down is also hard 
on the eyes, because the book or paper is often held in 
such a position that the eyes must be strained to see 
it. If you read while traveling or while lying down, 
rest your eyes occasionally and stop the reading be- 
fore the eyes have become fatigued. 
QUESTIONS 
How are the eyes protected from blows? from light and 
dirt? Where are the glands which secrete the tears? Of 
what use are the tears? What is the cause of scales on the 
edges of the eyelids? Explain how the eye is moved. What 
causes a person to squint? Name the coats of the eye. De- 
scribe the cornea; the lens ; the aqueous humor ; the vitreous 
humor; the iris ; the pupil. In what part of the eye are the 
nerves of sight? 
Explain how images are formed in a camera and in the eye. 
In what do the images in the eye start messages? What 
judgments does the brain form from these messages? 
How is the eye accommodated to near and far objects? 
What causes near-sightedness? far-sightedness? astigmatism? 
What is the effect on one’s health of a blurred image on the 
retina? How many school children in the United States need THE EYE 
333 
glasses? Why is it important, aside from improving the health, 
that glasses be worn by children who need them ? 
In what germ diseases are the eyes infected ? How should 
the eyes be cared for in these diseases? What is “pink-eye ”? 
“ granulated lids ” ? Name some things that should be avoided 
because they may allow germs to enter the eyes. 
From what direction should the light come when one is 
working? Why is it harmful to read or work by a dim light? 
Why is work that is held close to the eyes especially harmful 
to little children? How much window space should a school- 
room have ? Why is it harmful to read on a moving train ? 
while lying down? 
SUGGESTIONS TO THE TEACHER 
When medical inspection is lacking, the school should have a 
vision chart for examining the eyes. This is usually furnished free 
by city and state superintendents, or a copy may be bought for ten 
cents from Eyesight Conservation Council, Times Building, New York 
City. The following directions will allow a rough test to be made 
with the letters on page 329 : — 
Have a good light on the letters that are to be read. Seat the 
pupil at a distance of 20 feet from them. Test persons wearing 
glasses with their glasses on. Cover one eye with a card (but do 
not press on it) while the other is being tested. 
The upper line should be read at a distance of 30 feet and the 
lower lines at a distance of 20 feet. In case either eye fails to meas- 
ure up to this standard, glasses are needed. Persons who cannot 
read may be tested by asking them whether the letter E in the chart 
is open at the right, left, top, or bottom. In case the pupil knows 
the chart by heart, cut a small opening in a piece of cardboard and 
expose only one character at a time while the test is being made. 
Failure to read the letters by children under seven years of age 
does not necessarily mean that glasses are required. 
There may be defects of the eye that will not be revealed by this 
test. When there are symptoms of eyestrain, an eye specialist should 
be consulted. Directions for using the vision chart will be found 
on it. CHAPTER THIRTEEN 
THE EAR 
Fig. 97. The light waves start impulses in the nerve of sight, and we see 
the lightning; the sound waves start impulses in the nerve of hearing, and we 
hear the thunder. 
Doubtless you have seen a flash of lightning fall 
from the sky, and have stood and waited until the roll- 
ing of the thunder came to your ears. What was it 
that came to your eyes and caused you to see the 
lightning? It was waves in the ether.1 What was it 
that came to your ears and caused you to hear the 
thunder? It was waves in the air. Why can you not 
see the thunder ? It is because the eye is not af- 
fected by waves in the air; only ether waves can stimu- 
late the nerves of sight. Why is it that you do not 
hear the lightning ? It is because ether waves do not 
affect the ear; only air waves stimulate the nerves of 
hearing. 
1 Ether is an invisible, elastic fluid that fills all space. Light, the elec- 
tric waves that are used in wireless telegraphy, and the X-ray are waves in 
the ether. They run with almost incredible speed, light traveling at the 
rate of 186,000 miles a second. Air waves are very much slower than 
ether waves, sound waves traveling only about 1120 feet a second. 
334 THE EAR 
335 
Through the ear the confusion of air waves that 
comes from the instruments of an orchestra is trans- 
formed ihto music; through it we are able to under- 
stand the thoughts of 
a friend when he, by 
speaking, sends a 
series of air waves to 
us across a room. 
In the whole body 
there is nothing more 
wonderful than this 
instrument that has 
been given us to catch 
the waves in the air 
and carry their motion 
to the nerves of hear- 
ing, which lie deep in 
the bones of the skull. 
There are three main divisions of this organ,— the outer, 
the middle, and the inner ear. 
The outer ear. The outer ear is composed of carti- 
lage covered with skin. It catches the sound waves 
and turns them down a winding canal to the middle 
ear. When a dog, a horse, or a rabbit is listening, 
it holds up its ears to catch the sound waves, and 
a man sometimes puts his hand behind his ear to 
help in catching the sound and turning it into the 
ear. 
The middle ear. The middle ear is a little drum- 
shaped cavity in the bone of the skull. It is filled with 
air, and is connected with the throat by the Eustachian 
tube. At the inner end of the canal that leads inward 
mastoid 
cavity 
inner ear 
■nerve 
tympanic 
membrane 
middle ear Eusta- 
chian tube 
Fig. 98. Diagram of the ear. 336 
PRIMER OF PHYSIOLOGY 
from the outer ear is a little membrane called the tym- 
panic membrane. This stretches like a thin skin across 
the bottom of the canal and separates the outer ear 
from the middle ear. 
The bone of the skull behind the middle ear is 
spongy and has a cavity in it which is called the 
mastoid cavity. This opens out, like a little chamber, 
from the middle ear, and when germs infect the middle 
ear they often reach the mastoid cavity also. This 
trouble is called mastoiditis. In cases of this disease 
there is always danger that the germs will find their 
way to the brain and cause meningitis. 
The bones of the ear. Across the middle ear a chain 
of three small bones stretches from the tympanic 
membrane to the inner ear. These 
bones are called from their shape the 
malleus (hammer), the incus (anvil), 
and the stapes (stirrup). The malleus 
is fastened to the tympanic mem- 
brane ; the stapes fits into an opening 
that leads into the inner ear; and the 
incus is between the malleus and the 
stapes (Fig. 99). After we have 
studied the plan of the whole ear, we 
shall learn how these bones carry the motion of the sound 
waves from the tympanic membrane to the inner ear. 
The inner ear. The inner ear lies deep in the bone 
of the skull. It is exceedingly complicated in structure 
and we shall not attempt to explain it further than to 
say that it has three parts, — a central part called the 
vestibule, a coiled part called the cochlea, and three 
semicircular canals at the back that wind through the 
malleus 
incus. 
stapes 
tympanic 
membrane 
FIG. 99. The chain 
of bones of the ear 
connecting with the 
tympanic membrane. THE EAR 
337 
bone of the skull. The entire inner ear is filled with 
a fluid, and the fibers of the nerve of hearing end in 
such a way that when waves 
are set up in the fluid, the 
nerve endings are stimulated 
and messages are started in 
them to the brain. 
How a sound wave starts 
a message to the brain. 
When a sound wave strikes 
the outer ear, it is turned 
down the canal leading to 
the inner ear; it then strikes 
against the tympanic mem- 
brane and starts it to swing- 
ing out and in. This puts 
the malleus, the incus, and the stapes in motion, and 
the stapes is pushed in against the liquid in the inner 
ear. This sets up waves in the liquid, and the beat- 
ing of these waves stimulates the nerves of hearing and 
starts messages to the brain. When these messages 
reach the brain, we hear the sound. 
If the waves in the air are large and strike violently 
against the tympanic membrane, so that large waves 
are set up in the fluid in the ear, we say that the sound 
is loud. If the waves are small, so that the t/mpanic 
membrane and the chain of bones swing gen y to and 
fro, the nerves are stimulated only a little, and the sound 
is soft Within the inner ear is a wonderful mechanism 
which is so arranged that a sound having one pitch will 
start messages in one set of nerves, and a sound having 
a different pitch will start messages in another set of 
semicir- 
cular i 
canals j 
opening for stapes 
vestibule 
cochlea 
Fig. ioo. The inner ear. The 
lower figure shows the natural size of 
the inner ear. 338 
PRIMER OF PHYSIOLOGY 
nerves. By this arrangement the brain is able to tell 
the pitch of the different sounds that come to it. 
Earache and running ear. Practically all ear troubles 
are in the middle ear and are caused by germs. These 
germs work their way from the throat into the ear 
through the Eustachian tube, and they grow in the 
lining of the middle ear and about the little bones, much 
as they grow in the nose when we have ca-tarrh. 
Frequently, in diseases like colds, grip, scarlet fever, 
measles, and diphtheria, the ears become infected, and 
in these cases it is most important that a physician give 
them early and proper care. Often it is adenoids that 
start ear trouble, and in chronic cases of earache or 
running ears, adenoids should be looked for. 
It is not right to allow children to suffer needless pain 
from ear troubles, and they ought not to be left to out- 
grow them ; for a running ear already has a hole through 
the tympanic membrane, and the hearing is in danger 
of being lost. Nearly all deafness in older persons is 
due to the fact that when these persons were children, 
germs were allowed to grow in the ears until they dam- 
aged the tympanic membrane or the bones that carry 
the motion of the sound waves to the inner ear. Some- 
times the membrane or the chain of bones is broken 
down or destroyed. Sometimes the trouble is that the 
membrane is thickened and stiffened, or the chain of 
bones is stiffened at the joints until the movement in it 
is wholly or partly lost. Among grown persons about 
one third have the hearing affected in one or both ears. 
This could be prevented by attending to the ears at the 
proper time. 
Other points in the care of the ear. Quinine, if taken THE EAR 
339 
for a considerable time, may cause deafness, and this 
medicine, like other medicines, should be used only 
when prescribed by a physician. A blow on the side of 
the head is dangerous to the hearing ; for it may send 
so strong an air wave down the canal of the ear that the 
Fig. ioi. Testing the hearing. 
tympanic membrane may be broken. Live insects in 
the ear cause great distress by buzzing and moving 
about. They should be drowned by pouring warm 
water into the ear. 
No one but a physician should attempt to remove 
objects from the ear, because an unskilled person in 
attempting to do so may injure the lining of the canal, 
or break the tympanic membrane. In the canal of the 
ear there is a bitter wax secreted to protect the ear from 
insects. Children sometimes form a habit of picking 
at their ears with the head of a pin or other object. 
This causes the lining to become inflamed and the wax 
to be secreted too abundantly. One physician has said, 
“You should never thrust anything smaller than your 
elbow into your ear,” and another has added, “ Before 
you thrust your elbow into your ear you should wrap 
your coat around it.” If wax accumulates until it be- 
comes troublesome, a physician should be consulted. 340 
PRIMER OF PHYSIOLOGY 
QUESTIONS 
Describe the outer ear. What is its use? Describe the 
middle ear. What separates the middle ear from the outer 
ear ? What is the mastoid cavity ? What causes mastoiditis ? 
Name and describe the three bones of the middle ear. Where 
is the inner ear? Name its parts. With what is the inner 
ear filled? 
Where do the nerves of hearing end? Explain how a sound 
wave stimulates the nerves of hearing. What is the difference 
between a loud sound and a soft sound? Explain how it is 
possible for the brain to understand the pitch of a sound. 
How do germs enter the ear? In what parts of the ear do 
they grow? What is the most common cause of earache and 
running ears? What is the cause of nearly all cases of deaf- 
ness in grown persons? What per cent of adults have im- 
paired hearing? 
What bad effects have excessive doses of quinine? Why 
is a blow on the side of the head dangerous ? What damage 
may be done when an unskilled person attempts to remove 
objects from the ear? What is the use of the bitter wax in the 
ear ? What damage may be done by picking at the wax in the 
ears? 
In schools that do not have medical inspection the teacher should 
test the hearing. This may be done either with a watch (Fig. ioi) 
or by requiring the pupil to repeat words that have been whispered 
to him. Each ear should be tested separately. It should be im- 
pressed upon the pupils that deafness is rarely curable and that any 
ear trouble demands medical attention at once. 
SUGGESTIONS TO THE TEACHER CHAPTER FOURTEEN 
THE ORGANS OF TOUCH, TASTE, AND SMELL 
The sight and the hearing are especially important 
because they give us knowledge not only of near ob- 
jects, but also of objects that are far away. The sense 
of smell may also give us 
information of an object 
when it is at a distance; 
but in the main this sense, 
as well as the sense of 
taste and the sense of 
touch, is valuable because 
it enables us to judge of 
objects that are near at 
hand. 
There is not much that 
we can learn about any 
of these senses that is 
important from the stand- 
point of health. It is in- 
teresting, however, to 
know something of the way in which the messages that 
cause the sensations of touch, taste, and smell are started 
in the nerves, and to understand something of what we 
learn through these senses. In this chapter we shall 
therefore study the organs of touch, taste, and smell. 
Touch. The sense of touch is the most widely dis- 
tributed of all the senses, for we can feel through the 
skin on every part of the body. Through the sense of 
touch, even better than through the eye, we can learn 
the form of objects; through it we can tell whether ob- 
jects are smooth or rough, whether they are hot or cold. 
FIG. 102. A blind girl reading by sense 
of touch. 
341 342 
PR/MER OP PHYSIOLOGY 
Blind persons learn to read by passing the finger tips 
over raised letters, and persons who are both blind and 
deaf gain through the touch much of the information 
that comes to others of us through the eye and ear. 
The touch, therefore, is a sense that is not only at all 
times highly useful to us, but one that can be fur- 
ther educated and in time of 
need called into use to take 
the place of other senses. 
The endings' of the nerves 
of touch in the skin. The 
dermis, or lower layer of the 
skin, is thrown up into little 
peaks called papilla (singular, 
papilla) that stand up under 
the epidermis. Some papillae 
contain a great network of 
little blood vessels. Others contain a touch corpuscle, 
which is a little group of cells with a nerve fiber wind- 
ing about through it and ending in it (Fig. 76). Other 
fibers of the nerve of touch divide at the outer end into 
many little branches which end freely among the lower 
cells of the epidermis, or spread out into little saucer- 
like structures around the bases of 
some of these cells (Fig. 103). 
The nerves of touch are especially 
abundant in the fingers, lips, tongue, 
and tip of the nose, and in these places 
the sense of feeling is most acute. 
You can perform some interesting ex- 
periments by thrusting two or three 
pins through a piece of cork or wood 
Fig. 103. A nerve fiber ending 
around the bases of the cells in the 
epidermis. 
Fig. 104. TOUCH, TASTE, AND SMELL 
343 
(Fig. 104) and trying how far apart you must place them 
on different parts of the body to enable you to feel the 
points of the pins separately. 
Messages started by pressure in the nerves of touch. 
When we touch anything, the epidermis is pressed down 
on the ends of the nerves of touch. This starts impulses 
to the brain, and when these impulses arrive in the brain 
they cause us to feel. If all the nerve endings that are 
being stimulated have the same amount of pressure on 
them, we know that we are feeling a smooth surface. 
If some of them are being pressed harder than others, 
we know that the surface is rough. When we are 
touching an object, we know where the object is, be- 
cause we know from what part of the body the messages 
are coming. We know whether the object is large or 
small by the extent of skin surface that is touching it, 
and by the distance that we must move our hands to pass 
them over it. If you lay your hand against the wall, 
messages come in from the whole front of the hand, and 
you judge that you are touching one large object. If 
you feel two objects, like the points of two pencils, you 
know that there are two of them because the messages 
come from two places in the skin with a space between 
them in which the nerves are not being stimulated. 
Mistaken judgments concerning objects that we touch. 
The mind can make mistakes in judging of the messages 
that come in through the nerves of touch as well as in 
forming judgments from the messages that come in 
through the eye. Cross your fingers and rub them 
across the tip of your nose so that the nose is between 
the two fingers. Can you explain why you seem to feel 
two noses ? 344 
PRIMER OF PHYSIOLOGY 
Taste. The nerves of taste are in the mucous mem- 
brane of the tongue and of the back part of the mouth. 
Before anything can be tasted, it must first be dissolved. 
Then it works its way down among the cells and starts 
impulses in the nerves of taste. When these impulses 
reach the brain, we learn whether the object has a sweet, 
sour, bitter, or salt taste. Many of the supposed tastes 
of foods are in reality odors, and when because of a cold 
or for other reasons the sense of smell is dull, many foods 
are practically tasteless. The continual use of tobacco, 
alcoholic drinks, and strong condiments like pepper and 
tabasco sauce, permanently diminishes the sense of 
taste. 
The sense of smell. The sense of smell is probably 
the keenest of all our senses. It is likely that it is of 
use chiefly to judge whether 
or not our food is in proper 
condition to be eaten, and to 
tell whether air is fit to be 
breathed. Lower animals, 
like the dog, have this sense 
so highly developed that they 
can follow the track of a man 
or other animal many hours 
after the trail has been 
made. Among men, individ- 
uals differ greatly in the 
sharpness of their sense of smell. 
The nerve of smell stimulated by particles in the air. 
What we call an odor, or a smell, is in reality little particles 
of matter floating in the air. These particles come from 
a rose, from our food, or from anything that we smell, 
Fig. 105. The nerve of smell end- 
ing in the mucous membrane of 
the nasal chamber. TOUCH, TASTE, AND SMELL 
345 
and are drawn up into the nasal chambers with the air. 
In the mucous membrane that lines the upper part of 
these chambers are found the olfactory cells, from which 
nerve fibers run to the brain. When odors come in con- 
tact with the olfactory cells, impulses are started that 
cause the sensation of smell. 
Care of the organ of smell. When the delicate olfactory 
cells are destroyed, they are not renewed, and the sense 
of smell is permanently lost. They may be destroyed 
by inflammation, which is often brought on by inhaling 
dust or by working among the fumes of acids or other 
chemicals. Exhaling cigarette smoke through the nose 
is also very injurious to the cells, and many ciga- 
rette smokers have little or no sense of smell. Another 
common cause of the loss of the sense of smell is catarrh, 
which ought always to be treated by a good physician 
and not allowed to run on from year to year. When 
the throat is blocked by adenoids, the odors of foods 
cannot enter the nose as they should, and the pleasure 
of eating is to a considerable extent lost. The sense of 
smell is valuable to us both because of the pleasure 
that we receive from agreeable odors and because of 
the warnings that come to us in the way of disagree- 
able odors, and we ought to try to keep it in as good 
working condition as possible. 
QUESTIONS 
What do we learn through the touch? What is a papilla? 
Explain how the nerves of touch end in the skin. Where are 
the nerves of touch most abundant? 
When we touch an object, how are the impulses started in 
the nerves? How do we judge whether an object is rough or 346 
PRIMER OF PHYSIOLOGY 
smooth ? How do we know where it is ? How do we judge 
of its size ? 
Where are the nerves of taste ? How does the food reach 
the nerves of taste? Why can we not taste certain foods when 
we have a cold? How may the sense of taste be injured? 
What purpose does the sense of smell serve? What is an 
odor? Where are the nerves of smell? How are messages 
started in them? How may the sense of smell be injured? 
SUGGESTIONS TO THE TEACHER 
If the class has time for them, it will add interest to the work to 
perform a few simple experiments in touch, taste, and smell. Direc- 
tions may be found in any text of experimental psychology. Optical 
illusions also are interesting and they bring to the attention of the 
pupil the part played by the brain in sensation. 
In Figure 91 the iris may appear to be seen from either front 
or back, and other optical illusions may be found in texts of psychol- 
ogy or more advanced physiology. Common illusions that may be 
called to the pupil’s attention are: the fact that the letter s and the 
figure 8 must be made larger at the bottom to prevent their seeming 
heavier at the top; that the sun and moon appear larger on the 
horizon than when high in the sky; that from a railway train 
the landscape seems to be moving; and that when one looks at the 
mpon through the treetops while running, the moon seems to rut 
with him. CHAPTER FIFTEEN 
FOODS AND WHY WE NEED THEM 
FIGS. 106 and 107. The windmill gets its power to work from the wind which 
blows against it; the man gets his strength from the food that he eats. 
From my window I can see a windmill standing with 
its arms outlined against the sky. A little while ago 
it was whirling rapidly about and pumping water into 
the tank that it keeps supplied. Now it is standing 
motionless in the sunshine, as if overcome by the morn- 
ing heat. Is the windmill broken ? Or has anything 
happened to it that will keep it from any longer pump- 
ing water for its owner ? Not at all. The only trouble 
is that the wind which supplied the power to run the 
mill has for the time failed. 
Wherever there is motion and whenever work is done, 
power to cause the motion and to do the work must 
come from somewhere. We think of a swift and heavy 
automobile as a powerful machine, but in reality the 
power comes from the gasoline that is exploded in 
the cylinders, and when the supply of gasoline gives 
out, an automobile can no more move itself than can a 
stone. Every other machine, whether it be run by 
347 348 
PRIMER OF PHYSIOLOGY 
steam, gasoline, electricity, water, wind, or in any other 
way, must draw the power that runs it from some 
source outside itself. The windmill cannot run itself; 
it must stand and wait until the wind comes to give 
it motion and make it able to do its work. 
Food as a source of power. The human body has 
strength. It moves and does work. It cannot furnish 
itself with power, however, so we must have some source 
FIGS. 108 and 109. Food is necessary to furnish material for the repair and 
growth of the cells, and to keep up the body heat. 
from which to draw the strength that is in our muscles. 
This source of power is the food that we eat. Food is 
necessary to give strength to the body. Without it the 
muscle cells cannot contract and cause the movements 
of the body parts. 
Food as fuel. A locomotive as it thunders past us 
glows with warmth. It gets its warmth from the fuel 
that is burned under its boiler. A stove with a fire in it 
gives off heat to all the room. This heat comes not 
from the stove itself, but from the fuel that is burned in 
the stove. Your own body is warm, as you know from FOODS AND WHY WE NEED THEM 
349 
feeling it. The heat of the body comes from the food 
that is burned within the cells. Food is necessary to keep 
ap the body heat. Without it the temperature of the 
body would quickly fall to that of the air about it, and 
this would be fatal to the cells; for, as you already 
know, the cells can live and be in health only when the 
temperature of the body is close to 98 degrees (page 295). 
Food as building material. The human body is more 
wonderful than any machine made by man in that it 
builds its own parts and keeps them in repair. The 
body starts as a single cell, which is composed of 
protoplasm, or living material. This cell builds more 
protoplasm, increases in size, and divides, and this 
process is kept up until the full-grown body is finally 
built of living cells which have come from the first cell. 
Even after the body is grown, new cells must be built; 
for as long as life continues, the outer cells of the skin, 
the red blood corpuscles, and some of the other cells are 
dying and being replaced by new cells. 
New protoplasm is also constantly needed to repair the 
cells; for within all the cells the living protoplasm is 
constantly breaking down and new protoplasm is being 
built to take its place. The material that is used in all 
this building of living matter comes from the food that 
we eat. Food is necessary to furnish material for the 
growth and repair of the cells. 
Elements found in the body. The living matter of the 
body is composed of at least five different elements, 
all built together into a material that is very different 
from any of them. The black solid called carbon 
makes up over one half of the whole. The two gases 
of the air, oxygen and nitrogen, together with another 350 
PRIMER OF PHYSIOLOGY 
very light and highly explosive gas, called hydrogen, 
make up nearly all the remainder. In addition, some 
sulfur is built into protoplasm, and in the nucleus of 
the cell a little phosphorus is found. Among othei 
elements that are present in the body are chlorin and 
five minerals, — potassium, sodium, calcium, magnesium, 
and iron. It is not intended that you shall remember 
the names of all these elements, but it is intended that 
you shall understand that the body is made of perfectly 
definite materials, and that if these materials are not 
supplied in our foods, the body must suffer. 
The three classes of foods. Foods are divided into 
three classes, according to the elements of which they 
are composed. These classes are the proteins, the 
carbohydrates, which include the starches and sugars, 
and the fats. Lean meats, eggs, milk, peas, beans, 
and all foods made from grains are rich in protein. 
Potatoes, turnips, cabbage, and other vegetables are 
valuable mainly for their starch. Grains also contain 
large amounts of starch. Fruits, sweet potatoes, honey, 
molasses, and milk contain sugar, and we add great 
quantities of sugar to our foods to make it more 
pleasant to the taste. Fats and oils we get in butter, 
lard, fat meat, eggs, cheese, chocolate, nuts, and olive 
and cottonseed oil. In general, we get proteins and 
fats from animals, while from plants we get proteins 
and carbohydrates. From the table on page 482 you 
can learn the relative amounts of carbohydrates, fats, 
and proteins in different foods. 
Proteins the building foods. All three classes of foods 
give heat and strength to the body. The proteins fur- 
nish building materials in addition. They contain the FOODS AND WHY WE NEED THEM 
351 
same five elements that are found in the living matter 
of the body, — carbon, hydrogen, oxygen, nitrogen, and 
sulfur. Since they are used for building up the cells, 
we should expect them to contain these elements; for 
we use leather to patch a leather shoe, steel to replace 
a worn-out part in a machine, and to repair the body, 
the materials of which the body is built must be used. 
Minerals necessary to the body. A man excretes from 
his body nearly an ounce of mineral salts daily,1 and it is 
Fig. iio. Wild animals often travel long distances to salt-licks. Man 
supplies himself with salt, but he often lacks other minerals. 
necessary that certain amounts of the different minerals 
found in the body be supplied to make good this loss. 
In our food we always get small quantities of these min- 
erals, and little attention has been given to making sure 
that diets include a sufficient supply of them. Recent 
experiments show that this trusting to chance for the 
right amount of minerals is not always satisfactory. 
Not counting common salt, with which we all supply 
ourselves, the three minerals that may be lacking in our 
1 The greater part of this mineral matter is common salt, of which the 
average man uses daily from one third to two thirds of an ounce. This 
is more than is necessary for the health, for experiments indicate that one 
tenth of this amount is sufficient to keep the body in good condition. 352 
PRIMER OF PHYSIOLOGY 
food are iron, calcium (lime), and phosphorus. We 
shall discuss the need for each of these separately. 
Iron needed to build red blood corpuscles. Iron is used 
in the body mainly in building hemoglobin, the sub- 
stance in the red blood corpuscles that carries the oxy- 
gen. If the supply of iron falls too low, the person 
becomes pale and weak because of a lack of red cor- 
puscles and because of a lack of hemoglobin in the cor- 
puscles that he has. In cases of this kind the patient 
is given iron in liquid form as a medicine, and a little of 
this seems to be used by the body; but all physicians 
agree that for building hemoglobin the iron in food is 
far more valuable than iron in other forms. 
The green parts of vegetables, especially spinach, are 
rich in iron; and, in general, eggs, vegetables, and grains, 
when the outer portion of the grain is used, give a rich 
supply of this mineral. Milk is low in iron, and in ani- 
mals that feed their young on milk a large surplus store 
of iron is laid up in the body before birth. It is esti- 
mated that fifteen milligrams of iron are needed daily by 
a healthy man, and that the average diet contains from 
twelve to nineteen milligrams.1 This indicates that it 
would be very easy to select a diet that would be defi- 
cient in this important mineral. 
Lime needed by the body. Careful investigation 
has shown that growing animals require about 1.2 per 
cent as much calcium as they gain in weight. When 
this amount of calcium is not provided, the bones are 
frail and the teeth are soft and defective. There must 
also be a certain amount of calcium dissolved in the 
1 An ounce of iron would furnish the body with 15 milligrams a day for 
five years. FOODS AND WHY WE NEED THEM 
353 
lymph to keep the cells in health, and if the supply of 
lime be cut off entirely, life cannot continue. It is 
claimed that one half the people of the United States 
are suffering from lime starvation, and it is certainly 
true that many young children are not supplied with 
enough of this mineral. Adding a little limewater to 
artificial foods does not provide enough lime to be of 
much importance in building the skeleton and the 
teeth; for a pint of limewater as strong as it can be 
made contains slightly less lime than is contained in a 
pint of cow’s milk. Milk, eggs, vegetables (especially 
leaf vegetables), and whole grains hold the first place 
among the foods that are rich in lime (page 482). 
Lack of phosphorus in the body. Experiments indicate 
that from 65 to 90 milligrams of phosphorus are needed 
daily in the body, — an amount greater than many diets 
will supply. The yolk of egg, the outer layer of grains, 
peas, beans, chocolate, and nuts are especially rich in 
phosphorus. Meats also supply considerable quantities 
of this element to the body. Larger amounts of phos- 
phorus are needed during the growing period than in 
adult life, and if this is not supplied the bones are likely 
to become soft. 
Foods rich in minerals. It is perhaps worth while to 
call attention at this time to the fact that the foods on 
which young animals live while starting in the world 
supply minerals as well as protein and energy-yielding 
substances to the body. Milk has in it all the elements, 
except iron, that are necessary to nourish a young animal, 
and an egg has in it everything necessary to build a 
chick, including the iron for the blood corpuscles and 
the lime for the skeleton. 354 
PRIMER OF PHYSIOLOGY 
Foods which are rich in minerals ought to form a 
great part of our diet and be eaten by young people 
especially. Vegetables, also, because of the large quan- 
tities of them that can be eaten, furnish a rich supply 
of minerals to the body. In the body of an animal the 
lime is in the skeleton, and when we eat the meat we 
Figs, hi and 112. Eggs and milk contain all the 
elements necessary to start a young animal on its life- 
get little of this mineral.1 In wheat the mineral mat- 
ter is mainly near the surface of the grains and is not 
found in white flour.2 A diet, therefore, that is com- 
posed chiefly of meat and white bread is low in the 
minerals needed by the body. Whole wheat bread, 
oatmeal, breakfast foods, and, in general, vegetables 
and fruits, are rich in minerals. Children who are fed 
too long on milk suffer because of a lack of iron, and 
a meat diet supplies less mineral to the body than a 
vegetable diet. The diet of children in particular needs 
1 When a wolf or a fox eats a bird or a hare, it makes sure of a supply 
of calcium for itself by eating the bones as well as the flesh. Puppies fed 
only on lean meat and fat meat showed weakness of the bones, while 
other puppies of the same litter that were given bones to gnaw, in addi- 
tion to the meat, developed normally. 
2 The laxative effect of whole wheat bread is now believed to be due 
to the rich supply of phosphorus in it, and not to the irritating effects of 
the bran, as was formerly supposed. t FOODS AND WHY WE NEED THEM 
355 
care to make sure that the right minerals are contained 
in it, for there is a special need for mineral matter when 
the body is growing rapidly. Generally speaking, the 
mineral income of the body can be increased by cutting 
down the amounts of meat and white bread eaten and 
using milk and vegetables more freely. 
Vitamins. Within the last few years it has been dis- 
covered that certain substances called vitamins are 
necessary for health. We do not know exactly what 
vitamins are, but small amounts of them are found in 
our foods, and a good diet must contain them. They 
are destroyed by cooking with alkalis, and are therefore 
not found in corn bread or in biscuit made with soda. 
We are not sure how many vitamins there are, but 
two are definitely known to exist. One is present in 
whole grains, in beans, peas, potatoes, turnips, and other 
vegetables, and in milk and eggs. In our country almost 
every one secures enough of this vitamin, but the lack of 
it causes a disease of the nervous system called beriberi, 
which is responsible for many deaths among peoples 
who live chiefly on rice. The second vitamin is found 
in milk and butter, the yolk of eggs, and the green parts 
of vegetables. When animals are given a diet that con- 
tains none of this vitamin, growth does not take place 
and there is soreness of the eyes; and when the supply 
of vitamin is low, growth is slow and the health is poor. 
Many persons in our country do not get enough of this 
vitamin, and one of the chief reasons for the use of leaf 
vegetables and milk is to secure an abundant supply of 
it. 
Selecting foods. Of all the hygienic problems that 
confront mankind, that of selecting a proper diet is one 356 
PRIMER OF PHYSIOLOGY 
of the most difficult. Since the health of the digestive 
organs must be kept in mind as well as the needs of the 
body for certain materials, the whole subject can be 
entered into more intelligently after the digestive system 
has been studied. In the next chapter, therefore, we 
shall discuss the digestive organs and their work, and 
shall then take up the more difficult subject of selecting 
a diet that will keep the human body in health. 
QUESTIONS 
Give three uses of foods in the body. Name the five ele- 
ments that make up most of the body tissues. Name some 
other elements which are present in the body. Name the 
three classes of foods. What foods are rich in protein ? in 
starch ? in sugar ? in fat ? 
Which classes of foods give heat and strength to the body ? 
Which class furnishes building material ? 
For what is iron used in the body ? ' In what foods is iron 
abundant ? Why is lime necessary to the body ? What foods 
are rich in lime ? What foods are rich in phosphorus ? 
Why are milk and eggs complete foods ? Why is a diet of 
meat and white bread deficient in minerals ? 
What are vitamins ? What diseases are due to a lack of 
them ? In what foods is each vitamin found ? 
SUGGESTIONS TO THE TEACHER 
Sherman’s Chemistry of Food and Nutritio7i (Macmillan) gives 
tables of food analyses, an excellent general treatment of nutrition, 
and a particularly full treatment of the mineral constituents of the 
diet. McCollum’s The Newer Knowledge of Nutrition (Macmillan) 
;s a new book treating the subject from a very practical point of 
view. CHAPTER SIXTEEN 
THE DIGESTIVE ORGANS AND THEIR WORK 
Robinson Crusoe on his island had plenty of goats, 
and from goat hair a fine waterproof cloth is woven 
that is used as a covering for the tops of automobiles. 
Yet, because Crusoe had no way of turning the hair of 
his goats into cloth, he was forced to wear clothes made 
of stiff, heavy skins and to carry an absurdly heavy and 
awkward skin umbrella. There were trees in abun- 
dance on the island, but it required much labor to con- 
vert them into baskets, furniture, and boats. There was 
clay from which all kinds of dishes and vessels could 
have been made, but he went for years without tasting 
soup or boiled food, and he counted it one of the happy 
hours of his life when he succeeded in making a rude 
vessel that would stand the fire. There were tons of 
sand to be had from which glass might easily have been 
manufactured, but he had no windows in his dwellings. 
All about Crusoe were materials from which a thousand 
articles could have been made that would have added 
to his comfort and enjoyment, but until these materials 
were worked over and changed, he could not put them 
to use. 
The meats, grains, and vegetables that we eat contain 
the materials that are needed for the nourishment of 
our bodies, but the form of these foodstuffs must be 
changed before we can use them. As ice must be melted 
before the elements that are in it can be used by the 
body, so must our foods be digested before they can be 
taken into the blood and used by the cells. Digestion 
is the process of breaking rip and changing our foods into 
357 358 
PRIMER OF PHYSIOLOGY 
substances that can be dissolved and taken into the blood. 
Until this is done, our solid food is as useless to us as 
were most of the materials on his island to Robinson 
Crusoe. 
The digestive system. The digestive system includes 
the alimentary canal, the teeth, the salivary glands, the 
liver, and the pan- 
creas. The ali- 
mentary canal is 
the long passage- 
way through the 
body into which 
the food is taken 
and in which it 
stays while it is 
being digested. 
It is lined with a 
smooth mucous 
membrane, and in 
its walls are mus- 
cles to force the 
food onward 
through the 
canal. The teeth 
are a mill set at 
the mouth of the 
alimentary canal 
to crush and grind the food into small pieces so that it 
will be easier to digest. The other digestive organs are 
glands that pour juices into the alimentary canal to 
assist in the digestion of the food. The whole process 
of preparing the food for the use of the body is a most 
esophagus 
liver 
stomach 
.spleen 
■pancreas 
large 
intestine 
small 
intestine 
vermiform 
appendix 
Fig. 113. The digestive system. THE DIGESTIVE ORGANS AND THEIR WORK 
359 
important one, and the great set of organs that carry 
it on fill nearly the whole abdominal cavity. 
The digestive glands. The digestive glands are 
formed by the folding of the mucous membrane that 
lines the alimentary canal 
into deep little pockets. 
The juices that digest the 
food flow out of the mouths 
of these glands. The 
liquid part of the juices 
is composed of water that 
passes through the walls 
of the glands from the 
lymph, as water passes 
into a sweat gland (page 
297). Some glands are 
simple, like little wells 
sunk in the walls of the 
digestive tract. Others, 
like the salivary glands and the pancreas, are branched 
like a tree, and the juices that come from them are se- 
creted by hundreds of little tubules, all of which flow 
into the main duct of the gland. The glands are said 
to secrete when the liquid flows from them, and the liquid 
itself is called the secretion of the gland. 
The work of digestion done by enzymes. Dissolved 
in the secretions of the digestive glands are certain 
substances called enzymes. These are built up by the 
cells that compose the walls of the glands and are dis- 
solved by the liquid which passes through the cells 
when the glands secrete. The work of digesting the 
foods is done by the enzymes. An enzyme digests only 
vein 
connective 
tissue 
artery 
Fig. 114. Diagram of a simple gland. 360 
PRIMER OF PHYSIOLOGY 
one kind of food, so there are different enzymes secreted 
for breaking up the protein, fat, starch, and each of the 
different kinds of sugars that we eat. As we study the 
work of the cfifferent digestive juices, we shall speak of 
them as digesting the foods. You will understand, how- 
ever, that it is the enzymes in these juices that do the 
actual work of digestion. 
The salivary glands. There are three pairs of sali- 
vary glands. One pair lies under the tongue; one 
pair is found under the 
corners of the lower 
jaw; and the other pair 
is found in front of 
and below the ears 
(Fig. 115). These glands 
secrete the saliva, which 
is carried to the mouth 
by ducts leading from 
the glands. The saliva 
moistens the food and 
makes it possible to swallow food like crackers, which 
in a dry state would become dust in the mouth. 
Dissolved in the saliva is an enzyme which begins the 
process of digestion by attacking the starch that is in 
the food and breaking it up into malt sugar. 
The esophagus and stomach. The esophagus is the 
tube connecting the throat and the stomach. Food and 
drink do not fall down the esophagus, but are forced 
down it by the contraction of the muscles in the walls 
of the esophagus. This you can prove by drinking 
with your head lower than your body. 
The stomach stands almost on its end on the left side 
Fig. i 15. The salivary glands. THE DIGESTIVE ORGANS AND THEIR WORK 
361 
of the body close up under the diaphragm. It holds 
about three pints, and when full is about a foot long. 
When empty, its walls are drawn together and it 
occupies little space. It has a double function — to 
serve as a storehouse for food so that enough can be 
eaten at one time to supply the body for several hours, 
and to secrete gastric juice for the digestion of the food. 
The gastric juice. From two and one half to five 
quarts of gastric juice are secreted a day. It comes 
from the many hundreds of little glands which lie in the 
stomach wall and open into the stomach. The gastric 
juice contains an enzyme called pepsin that digests 
protein. It contains also an acid which kills many of 
the bacteria in the foods and so keeps these bacteria 
from causing trouble in the intestine. The acid in the 
gastric juice stops the action of the saliva on the 
starch, but in the upper part of the stomach the food 
may lie from one to two hours before the gastric juice 
works its way through it. The saliva, therefore, has a 
considerable time in which to digest the starch before 
the acid reaches it. The heat in the stomach melts the 
fat in the food, which assists in reducing the whole 
food mass to a liquid condition. 
The small intestine. The small intestine is coiled 
and folded upon itself in the abdominal cavity. It is 
about twenty-two feet in length and its walls are lined 
with thousands of little glands. These glands secrete 
an intestinal juice which contains several enzymes that 
are*important in the digestion of the food. On the 
intestinal wall are many little finger-like projections 
called villi (singular, villus'). These contain many blood 
vessels, and they absorb the digested food; that is, they 362 
PRIMER OF PHYSIOLOGY 
take it into the blood through the intestinal wall. So 
abundant are the villi that they give the entire inner 
surface of the intestinal wall the appearance of velvet. 
The liver and the pancreas. The liver weighs nearly 
four pounds and is the largest gland in the body. It 
lies on the right side of the body under the diaphragm. 
It secretes a greenish yellow liquid called bile, which 
is poured into the small intestine when food passes into 
the intestine for digestion. The bile assists in destroy- 
ing acids that come from the stomach, in making more 
active the enzyme that digests the fats, and in dissolv- 
ing the fatty foods. In the next chapter, we shall study 
other important functions of the liver. 
The pancreas is a long, light-colored gland which lies 
along the lower border of the stomach. It secretes and 
empties into the small intestine great quantities of thin, 
watery pancreatic juice. This liquid contains enzymes 
for digesting the three most important foodstuffs, — pro- 
teins, starches, and fats. The pancreatic and intestinal 
juices along with the bile are thoroughly mixed with the 
food in the small intestine, and they are even more im- 
portant than the gastric juice in preparing the food to 
be carried to all parts of the body. 
The large intestine. The large intestine begins low 
down in the right side of the abdominal cavity, passes 
up the right side of the body, then across under the dia- 
phragm, and down the left side of the body. Just below 
where the small intestine opens into it, there is a small, 
worm-like structure called the vermiform appendix. The 
walls of the vermiform appendix contain much loose 
spongy tissue of the same kind that is found in the ton- 
sils, and just as tonsillitis is caused by germs growing in THE DIGESTIVE ORGANS AND THEIR WORK 
363 
the tonsils, so appendicitis is caused by germs growing 
in the walls of the appendix. 
the food masticated and mixed with 
saliva 
starch digested by the saliva 
food mixed with gastric juice; pepsin 
'digests proteins; fats melted, and 
food liquefied 
food mixed with bile, pancreatic juice, 
and intestinal juice ; pancreatic juice 
digests proteins, starches, and fats; 
sugars digested to grape sugar by en- 
zymes in intestinal juice 
food continually cut into segments and 
mixed with digestive juices; digestion 
goes on, and digested food absorbed 
and carried away; a few bacteria 
present in refuse 
liquids being absorbed; mucus and 
wastes excreted by glands; abundant 
growth of bacteria 
continued growth of bacteria; wastes 
contain poisonous substances and 
should be removed from the body to 
prevent the poisons from being ab- 
sorbed into the blood 
Fig. 116. A diagram illustrating the changes that take place in the food during 
its journey through the different parts of the alimentary canal. 
The story of digestion. Let us now trace the history 
of a meal by imagining that we can see the food after it 
has been eaten, and that we can watch it while it is being 
digested. In the mouth we find that the teeth slide over 364 
PRIMER OF PHYSIOLOGY 
each other, crush the food into small pieces, and mix it 
with saliva. The enzyme in the saliva at once begins 
the process of digestion by attacking the starch that is 
in bread, potatoes, and many other of our foods, and 
changing it to sugar. 
After the food has been chewed, the tongue draws it 
back into the opening of the pharynx. The walls of the 
pharynx then grasp it and press it backward and down- 
ward into the esophagus, through which it is carried to 
the stomach. When the food reaches the stomach, the 
gastric juice trickles in on it from the glands in the walls 
all about, and the pepsin attacks the meats and other pro- 
tein foods. Under the action of the gastric juice the outer 
layer of the food mass dissolves and slides on into the 
lower part of the stomach, where the stomach walls con- 
tract on it and squeeze it about to mix the gastric juice 
thoroughly with it. 
From time to time the ring of muscle that closes the 
gateway between the stomach and the intestine opens, 
and a portion of the food from the lower part of the stom- 
ach is forced on into the intestine in the form of a thick 
liquid.1 Here a flood of digestive juices is poured in 
upon it. Greenish yellow bile comes from the liver; great 
quantities of juice rich in enzymes for digesting proteins, 
starches, and fats are secreted by the pancreas; and all 
along the small intestine, juices containing enzymes are 
poured out by the thousands of little glands that are in 
1 It should be understood that during stomach digestion the food is 
continuously being worked downward from the upper part of the stomach, 
and that from time to time it passes on into the intestine in rather small 
amounts. It takes about six hours for the stomach to be emptied after 
an ordinary meal. THE DIGESTIVE ORGANS AND THEIR WORK 
365 
the wall. The circular muscles in the walls of the intes- 
tine keep contracting on the food and cutting it up into 
little sausage-like segments which are continually being 
made, combined, remade, and moved about, thus mixing 
the digestive juices thoroughly with the food.1 All the 
time the food is gradually being worked along the in- 
testine and the enzymes are bringing about the following 
changes in it: 
The pancreatic juice attacks the protein and splits that 
which has escaped the pepsin of the stomach ; it breaks 
up the starch and completes the digestion of this 
part of the food; and it digests the fat, changing 
it into glycerin and other substances that will dissolve 
in the intestine. The enzymes in the intestinal juice 
assist in digesting the protein and in changing all the 
different sugars into the one particular sugar (grape 
sugar) that the body can use. 
And now as we follow the food in its course through 
the intestine, we notice that the liquid becomes less and 
less in amount; that only the solid wastes remain. As 
some desert rivers run out over the sand and lose them- 
selves in their own channels, so the stream of liquid 
food in the intestine disappears. Where is it going ? 
It is soaking into the wall of the intestine and passing 
into the millions of little capillaries that run in the 
wall. What will be done with it ? It will be car- 
ried through all the body to furnish heat and strength, 
and to be built into bone and muscle and nerve; for 
as the waterfall, even though it keep the same form, 
1 The segments into which the food is cut are about an inch long, and 
the contractions of the muscle rings come as often as thirty times a 
minute. 366 
PRIMER OF PHYSIOLOGY 
is made up of rapidly passing water, so our bodies, 
that seem to us to be the same year by year, are 
composed of materials that 
are ever shifting. The 
skin that we have today 
will, in a short while, be 
dead and gone, and the 
food that we eat today 
will be built into a new 
skin. The flesh and heart 
and brain of an ox are 
built of grass, and the 
human body is built of 
the food that we eat. 
The refuse matter in the large intestine. In all food 
there is some indigestible material like the woody, 
fibrous parts of potatoes and cabbages, the skins of 
fruits, and the tough fibers of meat. This matter passes 
from the small intestine into the large intestine, where 
its bulk is very considerably increased by mucus and 
other wastes that are secreted by the glands in the wall 
of the large intestine. In this waste material, millions 
of bacteria grow and cause decay, and in the process of 
decay poisonous substances are formed. Nothing is 
more important to the health than that this refuse ma- 
terial be cleared out of the intestine before the poisons 
are absorbed into the body. This question we shall 
discuss in the next chapter. 
Scurvy, rickets, and pellagra. The causes of these 
diseases are not definitely known, but they are in some 
way connected with the nutrition of the body, and we 
shall discuss them in this chapter. 
blood vessel. 
intestine_ 
Fig. 117. Showing the vessels which 
carry the food from the small intestine. THE DIGESTIVE ORGANS AND THEIR WORK 
367 
Scurvy is a disease in which the joints are swollen 
and tender and there is bleeding of the gums. It is 
found in infants that 
have been improperly 
fed and among sailors 
and others who lack 
fresh food. It can be 
prevented by fresh 
meats and fresh vege- 
tables and fruits, and is 
relieved in a wonderful 
way by orange juice. 
Some investigators have 
thought scurvy to be 
due to the lack of a 
vitamin. Others be- 
lieve it is caused by a 
bacterium that is able 
to enter the body when 
it is not properly nour- 
ished. Whatever the 
cause, the disease can 
easily be prevented by proper feeding. 
Rickets is a disease of children in which the bones 
are soft. The head grows larger than is natural and be- 
comes somewhat square, and there are knots on the ribs 
on either side of the breastbone where the bone and 
cartilage meet. It has been suggested that rickets is 
due to lack of a vitamin or to a lack of calcium, but 
neither of these explanations seems to be correct. It is 
in some way connected with bad feeding and is prevented 
and benefited by a properly selected diet. 
Fig. ii8. A milch goat. 368 
PRIMER OF PHYSIOLOGY 
Pellagra is common in Italy, and it is estimated that 
in the United States there were 165,000 cases in 1917. 
Most of these cases are found in the Southern states. 
The disease seems to spread only where the sanitary 
conditions are bad, and it is probably caused by a germ. 
At the same time, it has been proved that it is brought 
on by a faulty diet and that an abundant and varied diet 
with plenty of fresh foods will prevent it, even when 
sanitary conditions are bad. It seems most probable, 
therefore, that pellagra is caused by a germ that can 
attack the body only when it is in a weakened condition 
because of improper food. 
In our Southern states pellagra is a serious problem. 
A great number of the persons attacked by it live, during 
the winter months especially, chiefly on corn bread, salt 
pork, and molasses; and it is very necessary that milk, 
eggs, and fresh vegetables be added to this diet. The 
garden and poultry club movements, therefore, deserve 
every encouragement, and the keeping of milch goats 
might go far toward solving the diet problem of many 
families. Dried milk, which seems to have all the food 
value of fresh milk, is now being prepared. It may be 
that this will prove of great value in warm regions where 
providing a supply of fresh milk is especially difficult. 
Meats will not take the place of vegetables, eggs, and 
milk in providing minerals and vitamins for the body 
(pages 353-355)* 
What change must be made in foods before the body can 
use them ? What is digestion ? Name the parts of the digestive 
system. Describe the alimentary canal. What is the function 
of the teeth ? 
QUESTIONS THE DIGESTIVE ORGANS AND THEIR WORK 
369 
Describe a gland and explain where the secretion of the 
gland comes from. What is an enzyme ? By what is the 
work of digestion done ? 
How many salivary glands are there and where are they ? 
What is the function of the saliva ? What food is digested by 
the saliva ? Into what is it changed ? 
What is the esophagus ? Describe the stomach. What is 
the function of the gastric juice ? What enzyme does it con- 
tain and what is the function of this enzyme ? How are the 
bacteria killed in the stomach ? 
Describe the small intestine. What are villi ? What is their 
function ? Describe the liver. What does it secrete ? What 
is the use of the bile ? Describe the pancreas. What food- 
stuffs does the pancreatic juice digest ? 
Describe the large intestine. What causes appendicitis ? 
Tell the story of the digestion and absorption of food. 
Where is the food taken after it is absorbed ? 
Of what are the wastes in the large intestine composed ? 
Why is it important that these wastes be promptly cleared 
out of the body ? 
Name three diseases that are due to an improper diet. 
What foods will prevent scurvy ? What foods will prevent 
pellagra ? 
SUGGESTIONS TO THE TEACHER 
Additional information concerning the structure of the digestive 
organs and the processes of digestion may be found in Ritchie’s 
Human Physiology (World Book Company, Yonkers, New York). 
A fable by John W. Ritchie called The Adventures of the Starch 
Family will be found helpful in giving the pupils a concrete idea 
of the changes undergone by the foods during the digestive and 
metabolic processes. Application to the World Book Company will 
bring a copy of the pamphlet if four cents in stamps is enclosed. 
Howell’s Textbook of Physiology (W. B. Saunders Co., Philadel- 
phia) is an advanced text that will furnish a wealth of physiological 
information on almost any subject discussed in this book. Lusk’s 
Science of Nutrition (Saunders) gives a very thorough treatment of 
nutrition. CHAPTER SEVENTEEN 
THE FOODS WITHIN THE BODY 
We have now traced the food through its digestion. 
We have explained how it is taken into the blood and 
carried to the cells. 
What do the cells 
do with it ? What 
becomes of it after 
the cells have fin- 
ished with it? 
Why, when we 
keep eating all the 
time, does not the 
body become so 
full of food that 
we cannot take in 
more ? Perhaps it 
may start you to 
thinking about this subject in the right way if we go 
back for a few minutes to something else that you have 
seen. 
Long ago in your Mother Goose book you read: 
“ Little Nanny Etticoat, 
In a white petticoat 
And a red nose. 
The longer she stands, 
The shorter she grows.” 
Why does a lighted candle grow shorter the longer 
it stands? What becomes of the candle when it is 
burned? You must study chemistry before you will 
have a really clear idea of what happens in the process 
of burning. At present we can only explain to you 
Fig. 119. When the candle burns the elements in 
it axe not destroyed. 
370 THE FOODS WITHIN THE BODY 
371 
that the oxygen of the air unites with the elements of 
which the wax is composed and forms carbon dioxid 
and water, which pass off into the air. The materials 
in the candle, therefore, are not destroyed. They are 
merely changed to vapor and gas. 
The fate of the carbohydrates and the fats. The 
cells of the body take in the sugar and fats of the 
foods. They also take in oxygen. Within the cells the 
oxygen and the food unite slowly and without smoke 
or flame, and the food is oxidized, or burned as truly 
as the wax of a lighted candle is burned. This oxida- 
tion of the foods furnishes heat to the body and strength 
to the muscle cells; and, as in the burning of the candle 
the wax is changed to carbon dioxid and water, so 
within the cells the fats and carbohydrates are changed 
to carbon dioxid and water. The carbon dioxid is 
breathed out of the body through the lungs. The 
water is excreted by the lungs, the kidneys, and the 
skin. Thus the fuel foods are burned in the cells and 
the wastes which are formed from them are cast out of 
the body. The profit which the body receives from these 
foods is the heat and the power to do work which are 
given to the body when they are burned. 
The fate of the protein foods in the body. The living 
protoplasm of the body is continually breaking down 
and being oxidized. The protein food is used to build 
new protoplasm to take the place of that which is 
broken down.1 In time this protoplasm will also be 
broken down and oxidized, so that the proteins are as 
1 It should be understood that only a part of protein food is built into 
living tissue. Surplus protein and even part of the protein that seems to 
be necessary for life is oxidized as described on page 374. 372 
PRIMER OF PHYSIOLOGY 
truly burned in the body as are the carbohydrates and 
fats. The difference is that they are built into living 
material before the oxidation takes place. Carbon di- 
oxid and water are among the waste products that 
come from the burning of the proteins, but there are 
other wastes also, — uric acid and other similar sub- 
stances. These wastes are in- 
jurious to the cells, and the 
liver does a very important 
work in gathering up and con- 
verting a great part of them 
into urea, which is excreted 
from the body.1 We shall now 
describe the organs that elimi- 
nate the protein wastes. 
The kidneys. Fastened to 
the back wall of the abdomi- 
nal cavity are two bean-shaped 
organs, called the kid}ieys. 
Each kidney has in it many 
thousands of little tubes which 
all drain into a larger tube, the 
ureter (Fig. 120). The little 
tubes in the kidneys, like the 
sweat glands, are surrounded 
by lymph, and the water of the lymph passes into 
them and flows out of their mouths, as water passes 
Fig. 120. The kidneys and the 
bladder seen from behind. 
1 About 92.5 per cent of all the protein wastes excreted by the kidneys 
is in the form of urea. About 2 per cent of the whole is excreted in the 
form of uric acid, and it is estimated that an equal amount of uric acid is 
converted into urea by the liver. The uric acid part of the wastes comes 
from the nuclei of the cells and from the muscle cells when they work. THE FOODS WITHIN THE BODY 
373 
into a sweat gland and flows out on the skin. The 
urea and other protein wastes are dissolved in the lymph, 
and they leave the body by passing with the water 
through the kidney tubes into the ureter and draining 
off to the bladder. The function of the kidneys is to 
excrete water, salts, and protein wastes. 
Storage of the foods within the body. When more 
carbohydrate is eaten than is needed for immediate use 
in the body, it is changed to a starch-like substance 
called glycogen, and is stored within the cells of the 
liver and to a certain extent in the fibers of the 
muscles. When the supply of sugar in the blood runs 
low, this reserve store of glycogen is broken up again 
into sugar and given off into the blood to feed the cells. 
When more fat is eaten than can be used in the body, 
certain cells take it in and store it within themselves 
until they become little more than 
bags of oil. These cells, massed 
together, form the fat that you see 
in the body of an animal. When 
a person is sick and does not eat, 
the body uses this fat for food. 
A small amount of protein is dis- 
solved in the blood, but the great 
storehouse of the protein in the 
body is the muscles. The muscles 
are built up when we eat a diet that 
is rich in protein, and when for any 
reason we are deprived of food, the 
muscle fibers are broken down and 
used to nourish the cells of the heart, the brain, and 
other vital organs. Famine sufferers and persons who 
Fig. 121. Fat cells. They 
are little more than bags of 
oil. 374 
PRIMER OF PHYSIOLOGY 
have come through long sicknesses are little more than 
skeletons because their muscles have been used to sus- 
tain the organs necessary for life and the fat has been 
used to give the body heat and strength. 
Surplus food in the body. When we eat more carbo- 
hydrate than can be stored in the liver and muscles, it 
is converted into fat and stored in this form. Usually 
we lose our appetite for carbohydrates and fats when 
we have had enough to furnish a reasonable supply of 
fat in the body. We can, therefore, in most cases trust 
our appetites to tell us when we have had enough bread, 
potatoes, fat meat, butter, or other starchy or fatty foods 
(page 389). There are, however, a few persons whose 
cells oxidize these foods very slowly, and such persons 
become too heavy and fleshy if they eat freely of foods 
of this kind. 
When more protein is eaten than can be used or 
stored in the body, it is broken up, and excreted through 
the kidneys.1 From this protein the same wastes are 
formed that are formed from the breaking down of the 
protein of the body cells. A heavy diet of meat, or of 
other foods that are high in protein, therefore, gives the 
liver large amounts of protein wastes to change into urea, 
and sometimes more of these wastes are thrown into the 
blood than the kidneys can excrete. This subject we 
shall discuss in more detail in the next chapter. 
Alcohol as food. Alcohol in small quantities can be 
1 In the breaking up of the excess protein, the carbon and hydrogen in 
it are converted into either sugar or fat and used to give the body heat 
and strength. It is not to be understood, therefore, that surplus proteins 
are entirely useless to the body. The point is that they yield only energy, 
and this can be obtained much more cheaply from carbohydrates and fats 
without filling the body with poisonous wastes. THE FOODS WITHIN THE BODY 
375 
used to furnish strength to the muscles. In quantities 
up to two ounces a day it is oxidized within the cells and 
gives heat to the body. Because it can be used in these 
ways, it is often stated that it is a food. The modern 
idea of a food, however, is that it must not only furnish 
building material or energy to the body, but that it must 
also be harmless when it is broketi up within the cells. 
This definition of a food is, we think, a correct one; for 
certainly the toxin of the tetanus or the diphtheria germ 
is not a food, opium is not a food, and strychnin is not a 
food.1 Yet all these poisons are taken into the cells and 
are broken up in them, and they must furnish a small 
amount of heat to the cells. 
We cannot, therefore, say that alcohol is a food be- 
cause it is used by the cells, but before making our 
decision on this point we must know whether in being 
broken up within the cells it damages them — whether 
it interferes with those wonderful processes that keep 
the protoplasm alive. When we view the question in 
this light, we must decide that alcohol acts as a drug 
rather than as a food; for, as a drunken man shows, 
the action of the mind is dulled and made very uncertain 
by alcohol; under its influence the muscles are weak- 
1 Alcohol is composed of carbon, hydrogen, and oxygen. It is made 
from sugar, has in it the same elements that are found in sugar, and it 
would seem reasonable to expect it to act as a food toward the cells. We 
must, however, recognize that not only what elements are in foods and 
drugs, but also the way they are built together, is important ; for carbolic 
acid is built of the same materials and is closely related to sugar and 
alcohol, and strychnin and cocain are composed of carbon, hydrogen, 
oxygen, and nitrogen, — the same elements that are most abundant in 
protein foods. Just why substances that are composed of the same ele- 
ments should affect the cells so differently is hard to explain, but it is one 
of the facts of chemistry that we must accept. 376 
PRIMER OF PHYSIOLOGY 
ened and their control is lost; and its whole effect 
on the body is that of a drug and not of an ordinary 
food. Even in small amounts, — amounts far too small 
to produce signs of intoxication, — there is good reason 
to believe that alcohol interferes with the enzymes that 
break up the food within the cells and throws the life 
processes of the protoplasm out of their natural course.1 
QUESTIONS 
What becomes of the materials in a candle when the candle 
is burned ? What happens to the carbohydrates and fats within 
the cells of the body ? What becomes of the carbon dioxid 
that is formed in the body ? What becomes of the water ? 
What does the body gain by the oxidation of the fuel foods ? 
What is constantly happening to the protoplasm of the body ? 
What happens to the protein food before it is oxidized? What 
1 In the Hygienic Laboratory of the United States Government at 
Washington, an experiment was performed with mice and guinea pigs that 
gives reason for believing that alcohol does not act like ordinary foods 
within the cells. In this experiment, the animals were given acetonitrile, 
a drug that is not itself a poison but which breaks up into poisonous com- 
pounds within the body. When an animal was given along with the ace- 
tonitrile the smallest quantities of alcohol, the acetonitrile was broken up 
much faster than is natural and the animal was poisoned by a dose too 
small to have any appreciable effect when alcohol was not given. This 
proves that the alcohol changes the processes that go on within the cells. It 
does not, of course, prove that they are changed in a way that is injurious 
when acetonitrile is not given with the alcohol, but there is a quite wide- 
spread belief that even small quantities of alcohol have an evil effect on 
the changes that the protein foods undergo within the cells. Until we 
know that this is not the case, it is unreasonable to include alcohol in our 
list of foods. It should be understood that the above results followed the 
administration of alcohol in amounts “ far too small ever to cause indica- 
tions of intoxication and in doses which almost certainly cause no anatomi* 
cal lesions which could be detected by present methods.” THE FOODS WITHIN THE BODY 
377 
wastes are formed from the proteins ? Describe the structure 
of a kidney. What is the function of the kidneys ? 
How is carbohydrate stored in the body ? Under what con- 
ditions will the glycogen be changed again to sugar ? How are 
excess sugar and fat stored in the body ? Of what use is the 
fat in the body ? Where in the body is protein stored ? What 
happens to the muscles and fat of famine sufferers ? 
What happens if more protein is eaten than can be used or 
stored in the body ? In what way is a heavy protein diet inju- 
rious to the body ? 
Define a food. Why is alcohol sometimes classed as a food ? 
What reason is there for not including it among our foods ? 
SUGGESTIONS TO THE TEACHER 
Review the reasons why the body needs food. Have the pupils 
distinguish clearly between matter and energy. Emphasize the fact 
that except in the building foods it is the energy and not the matter 
that is valuable to the body, and that the useless matter has to be 
thrown out of the body as wastes. 
The books referred to on pages 356 and 369 give full accounts of 
the chemical reactions within the cells and of the wastes resulting 
from these reactions, and Chittenden’s Nutrition of Man (Frederick 
A. Stokes Company, New York) treats especially the question of 
the protein requirements of the body. Locke’s Food Values (D. 
Appleton & Co.) gives in convenient form the chemical and energy 
values of average helpings of prepared foods, and Gephart and Lusk’s 
Analysis and Cost of Ready-to-Serve Foods (Journal American Medi- 
cal Association, Chicago, price 15 cents) is of especial value to those 
who eat in restaurants. 
The teacher should write to the Child Health Organization, 
370 Seventh Avenue, New York City, for tables showing the proper 
weights for boys and for girls of given ages and heights. Attention 
should be called to the fact that the weight of the body represents 
the food that has been taken in by the body but not oxidized — the 
excess of income over outgo — and that the weight can be increased 
or decreased by regulating the intake of food. CHAPTER EIGHTEEN 
FOODS AND HEALTH 
How shall we know what foods we ought to eat and 
how much of each is best for us ? Occasionally the idea 
is advanced that in selecting a diet the best plan is to 
follow the appetite, — that the lower animals keep in 
health by eating the food they like, and that when the 
body calls for anything it does so because it needs it. 
It would be fortunate for us if by following this simple 
rule we could always be sure of keeping our digestive 
organs in order and of supplying our bodies with the 
materials that they need. But as a matter of fact this 
is not the case. Young rats that were allowed to eat 
freely of 23 different grains and vegetable foods failed 
to grow to more than half normal size, while other rats, 
compelled to live entirely on a mixture of rolled oats 
and dry alfalfa leaves, reached their full size. Certainly 
many persons crave foods that they know will be injuri- 
ous to them, and in the selection of foods, rules and prin- 
ciples must be followed as well as the appetite, if the 
diet is to be adapted to the body’s needs. The amount 
of protein needed by the body has in the past been one 
of the most disputed of all the questions pertaining to 
diet, and we shall begin this chapter by a discussion of 
that question. 
Quantity of protein needed by the body. When men 
are given an abundance of food and are allowed to select 
the kinds that they like, it is found that the average man 
consumes daily from four to four and one half ounces 
of dry protein. Some individuals eat far more and a 
378 FOODS AND HEALTH 
379 
few persons take much less than this amount, but a little 
over four ounces is the quantity of protein eaten by the 
average prosperous American or European. 
But many persons keep in health when eating much 
less than this amount of protein, and recent investiga- 
tions have shown that proteins differ from each other 
and that the amount of protein needed by the body 
depends upon the 
one that is taken. 
In digestion the pro- 
teins are split into 
amino-acids. These 
are absorbed into the 
blood and are used 
as the building stones 
with which the body 
repairs its wastes and 
grows. Nearly twenty 
amino-acids are now 
known, which differ- 
ent proteins yield in 
different amounts; 
some proteins lack 
certain amino-acids altogether, while others they furnish 
only in small amounts. For its building purposes the 
body picks out from the blood as much of each of the 
different amino-acids as it needs, using the remainder 
for fuel as it uses sugar and fats. 
Meat, fish, milk, and egg proteins are complete; they 
supply in large amounts all the amino-acids that the 
body needs. The proteins of grains, beans, and peas are 
low in certain amino-acids and must be eaten in large 
Figs. 122 and 123. A Roman and a Japanese 
soldier. They made their reputations as 
fighters on a low-protein diet. 380 
PRIMER OF PHYSIOLOGY 
amounts if they are the sole source of protein supply. 
Potato protein seems to be of good quality, although it 
is supplied in only small amounts. When a number of 
different kinds of foods are eaten, the amino-acids lack- 
ing in one food may be furnished by another, and thus 
all the needs of the body will be met. All the protein 
needs of the body can be met with vegetables, but in- 
cluding meat, milk, or eggs makes it much easier to plan 
a satisfactory diet. The proteins of soy beans and of 
peanuts are of better quality than most vegetable pro- 
teins. Gelatin is a protein of very low grade. 
The muscular endurance of low-protein subjects. All 
vegetarians live on a low protein diet. That it is pos- 
sible to maintain the body in health and strength on 
such a diet is shown by the muscular endurance of vege- 
tarians. In one seven-day walking race of 372 miles, 
two vegetarians won first and second places, beating 
the fastest flesh eater by 22 hours. In another great 
walking race of 124! miles, in which there were 
thirty-two competitors, the first six men who arrived 
were vegetarians, the seventh and eighth were meat 
eaters, and the ninth, tenth, eleventh, and twelfth 
were vegetarians. In January, 1912, the Edinburgh 
Marathon race (25 miles) was won by the Finnish 
runner, Kolehmainen, who is a vegetarian. This same 
man in the 1912 Olympic games at Stockholm went 
to the post on six successive days against the best 
runners of all the world, and six times he defeated 
them all so easily that he is declared to be “ the greatest 
of all Olympic heroes — the best long distance runner 
who ever wore spiked shoes.” 
Many other athletic contests have been won, and are FOODS AND HEALTH 
381 
being won, by vegetarians, but since in all cases of this 
kind much depends upon the individual, we shall give 
some average endurance tests that 
have been tried on a number of in- 
dividuals at the same time. Professor 
Irving Fisher of Yale University se- 
lected fifteen athletes who were living 
on a high-protein diet and tested their 
endurance. He found that on the 
average they were able to hold their 
arms extended for ten minutes. One 
man, who was a baseball pitcher and 
had powerful shoulder muscles, was 
able to hold his arm extended for 22 
minutes. The endurance of thirty- 
two young men, vegetarians and low- 
protein subjects, but not athletes, was 
then tested by the same method. 
These men were able to keep their 
arms extended on an average for 49 minutes, practically 
five times as long as their meat-eating competitors. One 
of them made a record of 200 minutes, more than nine 
times as long as the best high-protein athlete. 
Nine of the Yale athletes were then given the deep 
knee-bending test. On an average they were able to 
go through with this exercise 383 times. Twenty-one 
low-protein subjects were given the same test and their 
average record was 833 times. At a later time one of 
the low-protein subjects, a young man twenty-two years 
old, who had lived on a vegetable diet for two years, 
made the deep knee-bend 5002 times, 1555 times more 
than it was made by all the nine high-protein athletes. 
low 
protein 
high 
protein 
minutes 
Fig. 124. The low-pro- 
tein subjects held their 
arms extended for 49 
minutes on an average; 
the high-protein subjects 
for 10 minutes. 
minutes 382 
PRIMER OF PHYSIOLOGY 
Objections to a heavy meat diet. Because meat is rich 
in protein, much of the discussion as to the protein needs 
of the body has centered about the advisability of eating 
meat. Some persons have insisted that it is injurious 
to the body and that it should not be used at all as an 
article of food. As we have shown, it is possible to 
keep the body in health with a vegetable diet, provided 
milk is also used, but there is no proof that a moderate 
amount of meat is harmful to the average person. But 
because meats are pleasant to the taste, very large 
amounts of them are sometimes eaten. This is objec- 
tionable for the following reasons : 
(1) Meat does not supply the minerals and the vitamins 
that the body needs. If large amounts of meat are eaten, 
small quantities of other foods will be taken and some 
of the needs of the body may not be supplied. 
(2) Large amounts of meat in the diet cause poisonous 
substances to be formed in the intestine} When more 
protein is eaten than the pepsin and trypsin can digest 
in a reasonable time, part of it passes undigested into 
the large intestine. Here bacteria cause it to decay, and 
in the process of decay poisonous substances are formed. 
These poisons are then absorbed into the body, and they 
cause headaches and other disturbances by poisoning 
the cells. 
(3) Meat does not supply the bulk that is needed in the 
1 Individuals differ enormously in the kinds of bacteria that grow in the 
intestines and in the amount of poison formed by them, and these sub- 
stances are often abundant in the intestines of animals that live on a 
vegetable diet as well as in the intestines of meat-eating animals. Never- 
theless, it is true that in the average person a diet of vegetables and milk 
causes small quantities of the poisons to be formed, and a diet of meat and 
eggs causes an increased quantity of them to be formed. FOODS AND HEALTH 
383 
diet. The lack of bulky material causes the wastes to 
lie for a long time in the intestine, and this causes more 
of the poisons to be absorbed from these wastes than 
would be absorbed if they were promptly removed from 
the body. 
(4) A heavy meat diet loads the system with p7'otein 
wastes. This is probably injurious, in some cases at 
least. It has long been believed by nuyiy physicians 
that an excess of substances of the uric acid class is the 
cause of gout and other serious ailments. Part of the 
trouble, at least, seems to lie somewhere in the protein 
wastes, and the patients are benefited by cutting the 
protein to a low point. 
Because of these facts it is wise to eat only moder- 
ately of meats and to use other articles of food more 
liberally than they are used when meat is taken in large 
amounts. 
The energy needs of the body. The body must have 
enough food to provide it with heat and with strength fot 
the work that it does. A certain amount of food is 
burned in the body, even when the body is completely 
at rest. After eating, the amount of food burned by 
the cells is greater. When work is done by the muscles, 
the amount of food used is increased, — enormously in- 
creased if hard work is done.1 Exposure to cold causes 
the muscles to have a greater tension, and thus increases 
the amount of food burned in the body and the amount 
1 The energy content of food is measured by the heat it yields when 
burned. The unit of measurement is the Calorie, which is the amount of 
heat required to raise a liter of water one degree Centigrade. Roughly, it 
is the amount of heat required to raise one quart of water two degrees 
Fahrenheit. The body gets the equivalent of about 4 Calories of heat for 
each gram of dry carbohydrate or protein eaten, and about 9 Calories from 384 
PRIMER OF PHYSIOLOGY 
of heat released. Cold also causes a person to move 
about more, and to swing the arms and stamp the feet, 
which increases the heat production of the body; it may 
cause shivering, which brings still other muscles into 
use. In young persons the food is burned very rapidly 
in the cells, a boy or girl of ten or twelve years requiring 
as much food as a man or woman, and young persons of 
16 and 17 years much more than middle-aged persons. 
Women require somewhat less food than men, and in 
old persons the food is not used so rapidly by the 
cells. 
Effects of a diet that does not yield enough energy. A 
group of young men placed on a diet that yielded in- 
sufficient energy continued to grow thinner until they 
had lost a little more than 10 per cent of their weight. 
After that their bodies burned less food, and they con- 
tinued to live on this low level without further loss of 
weight. They did not become ill, but they lacked vigor, 
and when they attempted severe muscular exercise they 
found that they lacked strength for it. 
During the recent war many millions of persons were 
each gram of fat. An average-sized man needs enough food to yield the 
following numbers of Calories : 
Absolute rest in bed without food 1680 Calories 
Absolute rest in bed with food . 1840 Calories 
Office work or other light work, about 2500 Calories 
Light muscular work 2700 Calories 
Moderately active muscular work, as work of farmer or 
mechanic 3400 Calories 
Hard muscular work 4000 Calories 
Very hard muscular work 6000 Calories 
In a boys’ school where most of the pupils were from 13I to 16 years 
of age, the food used had a value of almost 5000 Calories for each pupil. FOODS AND HEALTH 
385 
forced to live on this low plane, and at all times great 
numbers of persons in all countries are undernourished. 
This is especially true of children; among both the rich 
and the poor great numbers of boys and girls are under- 
fed. Sometimes this is because not enough food is 
provided. More often it is because the child is not 
hungry and eats only certain of the articles of food that 
are placed on the table.1 Such children are in a low 
state of vigor, they do not grow fast enough, and it is 
believed that they have less resistance to infections than 
they would have if they were well nourished. The best 
indication as to whether enough food is being provided 
is the weight. 
Food for energy. Bread, grains, potatoes, butter, sugar, 
and fat meats are the foods on which we mainly depend 
for our energy. The body can use for fuel purposes any 
protein that is not needed for building material; but 
proteins are expensive foods, and, as we have seen above, 
it is not wise to eat too heavily of them. The thing 
to do, therefore, is to eat the proteins that we need for 
building material and then take enough fats, starches, 
and sugars to give us plenty of heat and strength. Usu- 
ally we can trust our appetites to tell us when we have 
had enough of these foods. Taking food into the body 
increases the amount that is burned in the cells, and the 
amount of body heat produced. Carbohydrates in- 
crease the heat production least, fats increase it more, 
1 The sensation of hunger is due to the contraction of the muscles of 
the stomach, and these muscles do not necessarily contract when the body 
needs food. It is generally supposed that children overeat, but far more 
of them do not eat enough. The trouble comes from the fact that they eat 
too much of sweets or other foods that gratify the appetite and refuse 
many articles of ordinary food. 386 
PRIMER OF PHYSIOLOGY 
and proteins increase it most of all. A winter diet, 
therefore, should be higher in fats and protein than a 
summer diet. Meat helps to keep up the body heat in 
winter, and a diet consisting largely of fruits and vege- 
tables is advisable on hot summer days. 
The mineral supply of the body. This subject has 
already been discussed (pages 351-354). In general, eat- 
ing large amounts of meat and sugar causes a lack of 
minerals, and a diet of vegetables and milk supplies 
minerals. Of all the minerals, the one most commonly 
lacking is calcium, which can be supplied by the free, use 
of leaf vegetables and milk. 
The vitamin supply. Whole grains, peas, beans, and 
vegetables contain abundant supplies of the vitamin that 
prevents beriberi. Milk is moderately rich in this sub- 
stance. Practically all of our population have enough 
of this material. The other vitamin is found in the 
leaves of plants, in the yolk of eggs, and in milk and 
butter. An animal like the cow or rabbit can eat enough 
grass or leaves to supply it with this vitamin, but a 
human being cannot do this. Milk and butter should 
therefore be used. The livers and kidneys of animals 
supply this second vitamin (it is found in cod-liver oil), 
and it is reported to be present in the fat of fish. 
General dietary principles. The seeds of plants are 
our chief source of food; wheat and corn bread, break- 
fast foods, oatmeal, rice, macaroni, peas, beans, and 
nuts make up the greater part of the diet of the people 
in temperate climates. Fruits and vegetables like pota- 
toes, turnips, and carrots furnish about the same elements 
to the body as grains. A diet composed of these foods 
is likely to lack certain of the needed amino-acids, FOODS AND HEALTH 
387 
calcium, and the vitamin found in leaf vegetables, eggs, 
and milk. Meat will make good the lack in the protein, 
but it will not supply the calcium or the vitamin, and to 
make the diet complete eggs or milk, or leaf vegetables, 
must be used. As we have already seen, it is difficult 
for man to eat enough green vegetables to supply the 
lacking substances, and for this reason eggs and milk, 
especially milk, should be used. Grains, vegetables like 
the potato, fruits, and meat do not make a complete diet. 
Leaf vegetables, milk, or eggs also are necessary. 
The importance of milk in the diet. All who under- 
stand the food needs of the body are agreed that it is a 
great misfortune that many families are using less milk 
than formerly because of an increase in its price. Milk is 
still one of the cheapest of our foods; a quart of it con- 
tains almost as much energy as a pound of steak, and it 
contains minerals and vitamins that can be supplied in 
an ordinary diet by nothing else. A certain organiza- 
tion that has long been at work to improve the diets of 
poor persons says that a quart of milk should be provided 
each day for a child and a pint for an adult. A noted 
authority on foods has stated that good milk is worth 
whatever it costs to produce it, and that no meat should 
be bought until each member of the family has been 
provided with a pint of milk. Another authority on 
foods reports that in his own family from 25 to 30 per 
cent of all the money expended for food is used in the 
purchase of milk. The most serious mistake made by 
our people in the purchase of food is in not buying 
enough milk. In the southern part of the United States 
it is especially important that the people in small villages 
and in the country provide a supply for themselves. 388 
PRIMER OF PHYSIOLOGY 
Large quantities of sugar injurious to the digestive 
organs. In his wild state man secured most of his sugar 
by eating starchy foods and digesting them to malt 
sugar. Now he prepares great quantities of sugar and 
uses it in his food, but the sugar that comes from cane 
and beets is cane sugar and not malt sugar. This sugar, 
when taken in large quantities, is very irritating to the 
stomach, and because in large amounts it is not a natural 
food for man we have but a small quantity of the 
enzyme that digests it. When a large amount of sugar 
is eaten, therefore, it may remain for a long time undi- 
gested in the small intestine, and when this occurs the 
sugar is likely to be fermented by bacteria and injurious 
acids formed from it. Sugar should be taken in moder- 
ate quantities, and it should be mixed with other foods 
and not eaten at a time when it will form a thick, sirupy 
solution in an otherwise empty stomach. A moderate 
quantity of candy eaten at the close of a meal has a very 
different effect on the digestive system from that of a 
large quantity taken before a meal. 
Fats. Fats hinder stomach digestion, and except in 
very cold weather few persons can take a daily ration 
of more than three and a half ounces of fat without bad 
results. Persons who suffer from acid stomach are ad- 
vised to eat liberally of fatty foods, and about two ounces 
of fat should be included in the average daily diet. 
Certain individuals who refuse to eat butter, fat meat, 
olive oil, or other fatty foods, live on very small quanti- 
ties of fat, and get their energy almost entirely from 
carbohydrates. This leaves the lipase without any work 
to do and throws a heavy task on the starch-digesting 
enzymes, and it is not so likely to give a well-ordered FOODS AND HEALTH 
389 
digestion as a mixed diet. It is also believed that the 
cells of the body keep in better health when part of their 
nourishment is supplied in the form of fat; that persons 
who eat little fat are more subject to germ diseases, 
especially tuberculosis, than are those who eat reason- 
able quantities of fatty foods.1 During the war more 
hardship seems to have been caused by a lack of fats 
than by a shortage of any other class of foods. 
Eating vegetables beneficial to the health. Coarse 
vegetable foods like string beans, cabbage, cauliflower, 
carrots, turnips, potatoes, beets, radishes, asparagus, let- 
tuce, celery, and spinach are very necessary to the health. 
They furnish minerals to the body and after they are 
digested there remains much bulky refuse matter that 
causes the wastes to be moved rapidly along the intes- 
tine. These are the foods that are least palatable to 
most persons, and they are the ones that are most fre- 
quently left out of the diet. One difficulty in getting 
enough of these vegetables into the diet is that in the 
country the family garden is often neglected and a suffi- 
cient variety of them is not produced. Another difficulty 
is that in towns and cities these vegetables are often 
needlessly allowed to wilt in stores and markets, and 
their tenderness is lost before they are cooked. The 
chief difficulty, however, is that only a few persons un- 
1 Fat is considered the most important part of the diet in tuberculosis. 
Outdoor life in this disease is more beneficial in cold climates than in warm 
climates and more beneficial in winter than in summer. Some physicians 
think that this is because in winter the exposure to the cold increases the 
appetite for fat. Milk and eggs have always been used as a source of 
much of the fat in the treatment of tuberculosis, and it is possible that a 
part of the benefits that are supposed to come from the fats in the diet is 
due to an abundant supply of the vitamin that is found in these foods. 390 
PRIMER OF PHYSIOLOGY 
derstand how to cook vegetables so that they will come 
to the table with the attractive flavors and odors that an 
expert vegetable cook can bring out. Because it is a 
difficult art to do this, many housewives give their atten- 
tion to the easier and simpler tasks of cooking meats and 
of making pies, cakes, and desserts, and serve on their 
tables vegetables cooked in an unappetizing way. It is 
very important that the proper attention be given to the 
raising and preparation of these foods, and every young 
person should learn to eat all the different kinds of 
vegetables that are served in his home. 
A plan for getting a proper diet. Since the very life 
of the body centers around the food from which the cells 
build their living substances and from which they get 
their energy, it is easy to understand that the question of 
diet is the most important problem of all hygiene. It is 
not possible to give any simple rules that will always be 
a complete guide in eating, but the following suggestions 
may be helpful: 
(1) Eat enough food. Only the energy needs of the 
body are increased by work, and laborers who eat large 
quantities of food are not nearly so likely to suffer from 
a lack of protein, minerals, and vitamins as those who 
take little exercise and eat only small amounts of food. 
Enough should be eaten to keep up the weight and vigor 
of the body. 
(2) Eat many different kinds of foods. As far as it is 
possible to do so, make it a rule to eat at each meal one 
food rich in protein, like lean meat, eggs, beans, or 
cheese; one or more starchy foods like breakfast foods, 
bread, macaroni, or potatoes ; some fatty food like butter, 
fat meat, or nuts; some coarse vegetable food like cab- FOODS AND HEALTH 
391 
bage, asparagus, turnips, or beets; a moderate amount 
of some sweet food like sugar, sirup, preserves, jelly, 
honey, cake, or a sweet dessert. Follow this plan, and you 
will probably not be tempted to eat too heavily of any one 
Figs. 125, 126, and 127. Healthful sports and games do much to prevent 
constipation. 
kind of food and will supply your body with all the dif- 
ferent materials that it needs. 
(3) Include milk mid butter in the diet. If this third 
rule is followed in connection with the two rules pre- 
viously given, the food needs of the body will be met. 
It is very important to follow some plan that will 
cause enough food to be eaten and all the different ma- 
terials that are needed to be supplied; for experience 
has proved that persons who simply follow their appe- 
tites or eat the foods that can be most conveniently 
secured frequently fail to supply their bodies with some 
of the materials that they need. 
Constipation a deadly enemy to health. No matter 
what diet is eaten, unless the wastes are rapidly moved 
along the intestine and promptly cleared out of the 
body, ill-smelling gases and poisons will be formed in 
the refuse matter in the large intestine. These will be 
absorbed into the blood and cause bad breath, headaches, 392 
PRIMER OF PHYSIOLOGY 
and other evil consequences. In selecting a diet, enough 
coarse food should be chosen to give large amounts of 
bulky refuse matter. This will assist in causing the 
wastes to be moved rapidly along the intestine. 
Other important points in the prevention and cure of 
constipation are vigorous exercise, especially bendings 
of the body and movements of the legs that will press 
the digestive organs about and help the circulation of 
the blood through them; massage of the abdomen, 
which also helps the circulation of the blood through the 
stomach, liver, and intestines; a daily cool or cold bath ; 
attending to emptying the bowels regularly at a certain 
hour each day1; eating foods like fruits, corn meal, and 
graham flour, which have a natural laxative effect; drink- 
ing large quantities of water, especially at bedtime; and 
keeping the nervous system in good condition so that the 
digestive organs will be properly regulated. A few 
physicians now understand how to treat successfully pa- 
tients suffering from constipation, and any one who suf- 
fers ill health month after month because of poisons 
produced in his own body should, if possible, put himself 
in charge of a physician who is especially qualified to 
treat this trouble. 
The cost of food. The object of eating is to supply 
the body with building material, heat, and strength. To 
1 An X-ray examination of animals shows that before the bowels are 
emptied the part of the large intestine which runs across the body is 
raised up partially on end and the part which runs up the right side of the 
body is dragged across to take the place of the transverse portion. It takes 
about 20 minutes for these changes in the position of the large intestine to 
be brought about. It is possible to train the nerves that control the intes- 
tine until they will set the muscles of the intestine in action at regular 
times, and it is exceedingly important to do this. FOODS AND HEALTH 
393 
make sure that all the needs of the body are supplied, we 
must eat foods of different kinds; we cannot live on 
corn meal and beans, no matter how cheap they may be. 
It is often possible, however, to supply the needs of the 
body either with high-priced foods or with other foods 
that may be purchased at a much lower rate. For ex- 
ample, the same amount of energy that can be purchased 
in wheat flour for four cents costs ninety-five cents in 
oysters, and protein costs nine times as much in canned 
corn as in corn meal. 
The average family is not wealthy, and according to 
the best statistics available it is slightly undernourished. 
We cannot go into the question of food costs further 
than to point out that in our country millions of dollars 
might be saved each year and the health of millions of 
people greatly improved, if the persons purchasing the 
food supplies of families understood how to secure the 
most nourishment for the money that they have to ex- 
pend. The average American family spends about one 
third of the money used for the purchase of foods for 
meats, fish, and poultry and less than one tenth of it for 
milk. Undoubtedly the diet would be improved by 
spending more for milk and less for meat. 
QUESTIONS 
Ho\y much protein is eaten daily by the average prosper- 
ous American or European ? Into what are the proteins split 
in digestion ? For what special purpose are amino-acids 
used by the cells ? How do proteins differ as to the amino- 
acids they supply? Name some foods that furnish protein of 
high grade; some foods that furnish less valuable protein. 
Give some arguments for a low-protein diet based on the 394 
PRIMER OF PHYSIOLOGY 
muscular endurance of vegetarians and other low-protein sub 
jects. Give four objections to a heavy meat diet. 
How much food does the body need? At what time of 
life is most food required ? What is the result of living on a 
diet that does not supply enough energy? What shows 
whether enough food is being provided ? Is your weight 
what it ought to be? 
What foods furnish an abundance of minerals to the 
body? What foods are rich in each of the vitamins ? 
Name some of the chief energy-yielding foods. What class 
of foods most increases the heat production of the body ? What 
foods can be used to increase the heat production of the body 
in winter ? What foods will keep the amount of body heat 
produced lowest in hot weather ? 
What other classes of foods supply the same materials as 
seeds ? What needed substances are lacking in these foods ? 
Explain how each of these substances may be supplied. 
Why is it important that milk be used freely? 
Why is sugar injurious to the stomach and intestines when 
eaten in large quantities ? When is the proper time to eat 
candy ? How much fat should be included in the daily ration? 
Why is it unwise to depend entirely upon carbohydrate foods 
for energy and to exclude fatty foods from the diet? 
Why are coarse vegetable foods necessary for the health ? 
Give some of the reasons why these foods are often omitted 
from the diet. 
Give three rules, for eating that will help in giving the body 
a proper food supply. Why is it important that some plan be 
followed in supplying the body with food ? 
Why is it necessary for the wastes to be promptly removed 
from the intestines ? How do coarse, bulky foods assist in 
this ? Give some important points in the prevention and cure 
of constipation. How does a knowledge of foods help in se- 
curing a satisfactory diet at a moderate cost ? CHAPTER NINETEEN 
The teeth are composed of the hardest tissues in the 
body, but decay of the teeth is the most common bacte- 
rial disease of man. Unlike many other infections, this 
disease runs on and on, and can be checked only by 
a surgical operation that removes the infected tissues 
and the germs that are in them. We have therefore a 
whole class of surgeons (dental surgeons) who give their 
entire time to the treatment and prevention of infections 
of the teeth and their surrounding parts. In recent 
years it has been proved that defective teeth are more 
injurious to the health than had been suspected, and the 
importance of keeping the teeth sound can hardly be 
exaggerated. 
How bad teeth injure the health. Bad teeth cause the 
food to be swallowed in large pieces and thus greatly 
delay digestion. They also allow germs to gain entrance 
to the bones of the jaw and establish centers of infection 
in these parts. These germs are usually slow-growing 
races of streptococci that live in the bones for years, and 
often the health is greatly injured by the toxins that are 
absorbed from them. Frequently the germs are carried 
from the teeth to other parts of the body and by grow- 
ing in these parts cause rheumatism, heart disease, kid- 
ney disease, and other ailments. This subject will be 
discussed in a later chapter (pages 446-454). 
The structure of a tooth. A tooth is composed of a 
crown, a neck, and one or more roots. The main bulk of 
the tooth is composed of dentine, or ivory, a substance 
harder than the most compact bone. The crown is cov- 
ered by a coat of enamel. This substance is very hard, 
THE TEETH 
395 396 
PRIMER OF PHYSIOLOGY 
but brittle like glass. The enamel can easily be broken 
by biting on hard objects, and it may be cracked by very 
hot food or drink taken into the mouth. If it is once 
broken off it is never replaced, and without the covering 
of enamel over it the den- 
tine soon decays. The 
roots of the teeth stand in 
sockets in the jaw-bones 
and are covered by a 
layer of bone-like cement. 
Lining the socketin which 
the root stands is a layer 
of connective tissue that 
fastens together the root 
and the bone of the jaw. 
In the center of the 
tooth is th z. pulp cavity, a 
little chamber containing 
nerves and blood vessels. 
Break open the tooth of 
an animal, and you will 
easily find the enamel, 
the dentine, the pulp cavity, and the little root canals 
through which the nerves and blood vessels enter from 
the jaw-bone. 
Why a tooth decays. Decay of the teeth is caused by 
bacteria that grow in the materials that stick to the 
teeth and lodge between them. It is thought that the 
bacteria start the decay by forming acids that eat away 
the enamel. Then other kinds of bacteria enter the 
cavity and destroy the dentine. If the decay is allowed 
to go on until the pulp is reached, this is killed and the 
enamel 
dentine 
gum 
pulp 
bone 
bundle of nerves, 
veins, and arter- 
ies for pidp 
Fig. 128. A section through a tooth 
showing its structure and how it is fas- 
tened into the jaw-bone. THE TEETH 
397 
germs not only grow in the dead pulp but enter the jaw- 
bone through the root canal and set up their growth 
about the end of the root. When the decay is reaching 
the pulp, but when the nerve endings in the pulp are 
not yet dead, the tooth may ache. A gum boil is due to 
infection at the root of a tooth. 
The teeth preserved by keeping them clean. The way 
to preserve the teeth is to keep them clean, so that 
bacteria cannot find a home around them. The teeth 
should be brushed both inside and outside after each 
meal, and food that is lodged between them should be 
carefully removed. This point is important because 
decay nearly always begins between the teeth. Some 
dentists recommend that the food be removed with den- 
tal floss, but in the hands of the average person a tooth- 
pick is more effective. A quill pick is less likely to 
injure the gums than a wooden or metal one. Rinsing 
water about vigorously in the mouth and driving it be- 
tween the teeth removes many small food particles, and 
this should always be done after the teeth have been 
brushed. 
A good tooth powder or paste is an aid in cleaning 
the teeth. Prepared powders or pastes may be used, 
or a good powder made of precipitated chalk and 
powdered orris root, 
which may be pur- 
chased from any drug- 
gist. Charcoal, pumice 
stone, or other gritty 
substances should not 
be used, as they scratch 
the teeth and leave 
Fig. 129. A curved brush with the bristles 
longer at the ends cleans the teeth better than 
a straight brush. 398 
PRIMER OF PHYSIOLOGY 
little grooves in the surface where food and bacteria 
collect. A curved brush with the bristles longer at the 
FlG. 130. One half of the permanent set of teeth. 
ends cleans the teeth better than a straight brush ; a 
medium-sized brush with moderately stiff bristles should 
be used. 
Deposits on the teeth. The mucus of the saliva forms 
a film over the teeth, and in many mouths patches of 
gummy material collect on the teeth where they are not 
cleaned in chewing the food and by brushing. These 
deposits are called dental plaques, and they are filled 
with living bacteria that produce acid and start decay 
beneath the plaques. Tartar is a hard mineral deposit 
that usually forms most abundantly along the edge of 
the gums. It is often stained brown by the escape of 
blood into it and may become bluish, green, or almost 
black from changes in the coloring matter of the blood 
in it. 
Thorough brushing of the teeth helps to keep them 
free from dental plaques and tartar, but these may ap- 
pear on places where the brush cannot reach them or THE TEETH 
399 
even, in spite of the most careful cleansing, where the 
brush does reach. It is important, therefore, to visit 
a dentist from time to time to have any deposits on 
the teeth removed. 
The care of the gums. In many persons the gums are 
slightly inflamed along the margins and bleed easily 
when they are brushed. To keep them in health it is 
very important that tartar on the teeth be removed, for 
the tartar irritates the gums and causes them to shrink, 
leaving the roots of the teeth bare. This inflammation 
and receding of the gums may allow germs to work 
down about the roots of the teeth and form pus about 
them, thus causing them to become loose in their sockets. 
When the teeth are cleaned, the gums should also be 
thoroughly brushed with a light, quick stroke that will 
stimulate the circulation in them but will not injure them. 
One dental authority states that inflamed gums can be 
surely restored to health if the gums and teeth are 
brushed in the proper manner for two minutes four times 
a day. Some writers advise that in cleaning the back 
teeth the brush be given a twisting movement, and that 
the brushing be always from the gums toward the crowns 
of the teeth. Others believe that the outer surfaces of 
the back teeth can be best cleansed by giving the brush 
a circular or rotatory motion. All authorities are agreed 
that the brushing should not be crosswise on the teeth. 
The purpose of brushing is to prevent cavities from 
forming in the teeth and to keep the gums in health, and 
the brushing should be frequent enough and thorough 
enough to accomplish this purpose. It is best to have 
two tooth brushes, as a brush becomes soft when too 
frequently used. 400 
PRIMER OF PHYSIOLOGY 
The importance of visiting the dentist frequently. It 
is very important that the teeth be inspected by a den- 
tist at regular intervals and be given any treatment 
they may need. If the dental plaques are not removed, 
decay may start beneath them. Tartar that is not re- 
moved irritates the gums and causes them to become 
inflamed and to shrink. A most necessary part of the 
care of the teeth, therefore, is to have any deposits 
on them removed promptly, and a dentist should exam- 
ine the teeth every three months to see if this needs to 
be done. 
It is also important that cavities be filled while they 
are yet small, both because this plan preserves the teeth 
and because it is more economical and less painful than 
waiting until the cavities have enlarged and a great part 
of the tooth has been eaten away. All over the land 
people are suffering with toothaches and paying for ex- 
pensive X-ray work, root fillings, and crown and bridge 
work when they could have preserved their teeth by 
spending a mere fraction of the same money at an earlier 
date for small fillings. If the pulp of the tooth dies and 
the germs gain entrance into the bones of the jaw, it is 
exceedingly difficult to eradicate them and sometimes it 
is impossible to do so. It is not considered safe to fill a 
dead tooth unless the X-ray is used to make sure that the 
filling extends to the end of the root canals; even after 
the roots are filled it is considered advisable to put a tem- 
porary filling in the tooth, and after a time to examine it 
again with the X-ray to make sure that no infection has 
developed in the bone at the tips of the roots. Dental 
work of this kind is very expensive, and it is much more 
satisfactory to have the teeth attended to when only THE TEETH 
401 
cleaning and small fillings are required. Unless decayed 
teeth can be so treated that they will be free from 
germs, it is better to have them extracted, and there are 
not a few dentists who believe that a dead tooth is better 
out of the mouth than in it. 
The temporary teeth. The jaws are too small in child- 
hood to hold the large teeth that we need in later life. 
In early life we have, therefore, a set of twenty small 
temporary teeth. This set is composed of four incisors, 
two canines, and four molars in each jaw (Fig. 132). 
The incisors are flat and chisel-like for biting off the 
food. The canines are more round and pointed, and in 
the dog and other carnivorous animals they are used as 
weapons and for tearing flesh. The molars are broad, 
square teeth with square cusps, or points, and wide sur- 
faces for crushing and grinding the food. About the 
sixth year the temporary teeth begin to drop out, and 
by the twelfth or fourteenth year they have all been 
replaced by permanent teeth. 
The permanent teeth. There are thirty-two perma- 
nent teeth. In each jaw there are four incisors and 
two canines that replace 
the incisors and canines 
of the temporary teeth ; 
four bicuspids in place of 
the temporary molars; 
and six molars that come 
in behind the space occu- 
pied by the temporary 
teeth. The first perma- 
nent molars appear about 
the sixth year. The third 
Fig. 131. The tooth on the right de- 
cayed, the roots were not absorbed, and 
the tooth had to be pulled to make room 
for the permanent tooth. The tooth in 
the middle shows the roots partly ab- 
sorbed. The roots of the tooth on the 
left have been completely absorbed and 
the tooth has dropped out. 402 
PRIMER OF PHYSIOLOGY 
molars, or wisdom teeth, usually appear from the six- 
teenth to the twenty-first year, but in some persons these 
teeth never make their way through the gums.1 
The importance of caring for the temporary teeth. The 
first reason for caring for the temporary teeth is that 
they themselves are nec- 
essary for the health ; for 
if they are allowed to de- 
cay, the child will form 
the habit of bolting his 
food ; the digestion will 
be deranged by the germs 
that are swallowed ; and 
the nervous system and 
the disposition will be 
damaged by the pain 
from the toothache that 
the child will be com- 
pelled to endure. For 
the sake of the health during the years of childhood and 
to prevent the forming of wrong eating habits, the tem- 
porary teeth should have the best of care. 
The second reason for caring for the temporary teeth 
is to prevent the permanent teeth from coming in irreg- 
ularly. The permanent teeth begin to form long before 
incisors 
canine 
molars 
Fig. 132. The upper temporary teeth of 
a child about three years old with the 
average time of eruption given in months. 
The lower teeth usually appear a few 
weeks earlier than the upper. The first 
permanent molars, which at this time are 
being formed in the jaws, are shown be- 
hind the temporary teeth. 
1 Sometimes when the wisdom teeth or other teeth fail to appear at the 
normal time it is because they have turned sideways in the jaw or have 
become tightly wedged among the roots of the other teeth. Teeth that 
are lodged in the jaw in this way are called impacted teeth, and there are 
many cases on record of persons who suffered greatly from nervous troubles 
because of the pressure such teeth were exerting. If the teeth do not ap- 
pear at the proper time and there is any trouble with the health, impacted 
teeth should be looked for. The X-ray is used in making the examination. THE TEETH 
403 
birth at the roots of the temporary teeth, and by the end 
of the third year even the wisdom teeth are formed in 
the jaws. These teeth then gradually grow and harden, 
and the roots of the temporary teeth disappear before 
them (Fig. 131). Finally, the roots of the temporary 
teeth are entirely absorbed and the first teeth drop out, 
leaving the places they occupied to the permanent teeth. 
If the temporary 
teeth are allowed to 
decay, their roots are 
not absorbed before 
the permanent teeth. 
The second teeth, 
therefore, either re- 
main buried in the 
jaws or appear in an 
irregular line, some 
inside and some out- 
side of the line of the 
first teeth. Another 
difficulty caused by decay and loss ot the temporary 
molars is that when the first permanent molars come in 
they move forward and take positions that belong to the 
bicuspids and there is then not enough room for the per- 
manent bicuspids. For the sake of the permanent teeth, 
therefore, the temporary set should have the best dental 
care, and if for any reason they have been allowed to de- 
cay, a dentist should be consulted when it is time for the 
second teeth to appear. Permanent fillings and not 
cement fillings should be used in the temporary teeth, 
for some of these teeth remain in the mouth until the 
child is 10 or 12 vears of asre. 
incisors 
bicuspids 
canine 
molars 
Fig. 133. The upper permanent teeth of a man 
twenty-six years old, with the average time of 
eruption given in years. The lower teeth usu- 
ally appear two or three months earlier than the 
corresponding upper ones. 404 
PRIMER OF PHYSIOLOGY 
The importance of caring for the first permanent molars. 
The first permanent teeth, which come in about the sixth 
year, behind the tem- 
porary molars, are of- 
ten mistaken for tem- 
porary teeth. These 
molars have deep 
grooves in their sur- 
faces in which the food 
lodges, and they come 
into the mouths of 
many children before 
the habit of washing 
the teeth has been 
formed. They are therefore especially liable to decay. 
They should be filled at once if cavities appear in them, 
because they are not replaced when lost, and without 
them the jaws do not grow in length as they should. 
Count the double teeth in the mouth of a six- or seven- 
year-old child, and if there are three of them on one side 
of the jaw, the back one is a permanent molar. 
Other points in the care of the teeth. Sticky foods like 
oatmeal and mashed potatoes cling to the teeth and cause 
them to decay. Hard foods like apples, cornbread, and 
bacon clean the teeth and give the gums the exercise 
that is needed to keep up the circulation through them. 
Every diet, therefore, should contain some tough, solid 
material into which the eater can set his teeth. Sugar 
left among the teeth ferments easily and causes decay. 
For this reason eating candy at all hours of the day, so 
that the crevices among the teeth are kept filled with 
it, is almost sure to cause decay. 
bicuspids 
canine 
first molar 
incisors 
first 
molar 
incisors 
canine' 
bicuspids 
Fig. 134. The jaws of a child four years 
old. The jaw-bones have been cut away to 
show the permanent teeth growing at the 
roots of the temporary set. THE TEETH 
405 
Straightening irregular teeth. Often the permanent 
teeth come in irregularly and are turned forward in 
front because the temporary teeth have been allowed to 
decay or because adenoids or nasal growths have kept 
the bones of the jaws and of the roof of the mouth 
from growing enough to make room for the teeth. 
When for these or any other reasons the teeth are ir- 
regular, a dentist who understands how to straighten 
them should at once be consulted. By putting pressure 
on the teeth the bones may be made to grow larger and 
the arch of the jaw ex- 
panded until the teeth 
have sufficient room. 
Figure 136 gives an 
idea of the changes 
that a good dentist 
can make in the ap- 
pearance of a person 
whose mouth is 
spoiled by irregular or protruding teeth. The work of 
straightening the permanent teeth ought to be begun 
as soon as they appear, and not delayed until all of them 
are in the mouth, as is often advised. A tooth that has 
been crowded out of line ought not to be pulled, but the 
circle of the teeth should be widened until there is room 
for all. 
Defective teeth due to illness and to lack of calcium 
in the diet. A tooth is first built up by the growth of 
a “ bud,” or little group of cells of the mucous mem- 
brane which covers the jaw. It is then hardened by 
having calcium deposited in it. This hardening of the 
teeth is going on all through childhood, and severe cases 
Fig. 135. This shows how the upper teeth 
should close on the lower teeth. (After a 
photograph from “ The Practical Ortho- 
dontist.”) 406 
PRIMER OF PHYSIOLOGY 
of scarlet fever, measles, diphtheria, and other illnesses 
may interfere with the deposition of lime and cause the 
teeth to be soft and ill-formed when they come through 
the gums months or years later. 
Defective teeth may also be caused by lack of cal- 
cium in the diet, as we have already pointed out (page 
352). It is therefore especially important to the teeth 
Fig. 136. Two cases in which the teeth needed and received the care of a 
good dentist. (After a photograph from “ The Practical Orthodontist.”) 
that children be guarded from disease and that an abun- 
dance of lime be supplied in the food during the early 
years of life. The question of lime in the diet should 
be given special care when babies are brought up on 
any food other than milk. 
Care of the mouth of an infant. Little babies often 
suffer from sore mouth. This disease is caused by 
germs and is usually brought on by lack of cleanliness. 
It should be promptly attended to by a physician, be- 
cause it not only causes suffering and nervousness in 
the child but also fills the alimentary canal with germs THE TEETH 
407 
and ruins the digestion. When the teeth are making 
their way through the gums, the mouth should be ex- 
amined to see that there are no little ulcers on the gums 
when the teeth are cutting through. If these are found 
a physician or a dentist should be consulted; for it is 
very unwise to allow a child to go on swallowing the 
many thousands of pus-forming germs that come from 
the ulcers. One of the best means of preventing trouble 
in the mouth of a baby is to wipe out the mouth, after 
feeding, with a clean cloth that has been dipped in a sat- 
urated solution of borax or boric acid. 
Decayed teeth very common. Among the 846 children 
examined in a school in Cleveland, Ohio, only three 
had perfect teeth. Examinations of many thousands of 
other children show that often as many as 95 per cent 
of them are in need of dental care. The great majority 
of young persons lose their first permanent molars before 
they are twenty years of age, and it is undoubtedly true 
that no other part of the body is so often defective as 
the teeth. You should be on guard, therefore, to pre- 
serve the precious heritage which nature has given you 
in the form of your teeth ; for your chances of health in 
later years depend very largely on the care that you give 
your teeth now. Keep them clean by all means, and 
if there are small cavities in them, have them filled at 
once. 
QUESTIONS 
In what two ways do bad teeth injure the health? Name 
the parts of a tooth. Of what is the body of a tooth com- 
posed? With what is the crown covered? How may the 
enamel be injured? What results usually follow breaking 408 
PRIMER OF PHYSIOLOGY 
the enamel ? How are the teeth fastened in the sockets ? 
Where is the pulp cavity ? What does it contain ? 
What causes decay of the teeth ? What happens if the decay 
continues until the pulp is reached ? How may decay be pre- 
vented? Why should particles of food that lodge between 
the teeth be removed? How may a good tooth powder be 
made ? Why should gritty substances not be used to clean 
the teeth ? What kind of brush is best for cleaning the teeth ? 
What are dental plaques ? What is tartar ? Give two 
important points in keeping the gums in health. How should 
the brush be used in cleaning the teeth ? How often should 
the teeth be brushed ? 
Why is it important to visit the dentist regularly ? Why 
should dental plaques be removed? Why should tartar be 
removed ? Explain why it is important to have all cavities 
filled while they are small. 
How many teeth are there in the temporary set? Name 
and describe the different kinds. How many teeth are there 
in the permanent set ? When does the first permanent molar 
appear ? Give two reasons for caring for the temporary teeth. 
Why are the first permanent molars especially liable to decay ? 
Why is their loss harmful ? 
Why are hard foods better for the teeth than sticky foods ? 
Why is constant candy eating injurious ? How do adenoids 
and nasal growths affect the teeth ? What should be done 
when the teeth are crooked ? How may illness during child- 
hood injure the teeth ? What element needed for building 
the teeth is sometimes lacking in the diet of children ? 
When babies have sore mouth, what is usually the cause ? 
What trouble should be guarded against while the teeth are 
coming through the gums? How can trouble in a baby’s 
mouth be prevented? 
Cite some facts to show how common defective teeth are. CHAPTER TWENTY 
TOBACCO 
FIG. 137. The peace pipe. 
When Columbus returned from the West Indies, he 
reported that the natives carried with them to kindle fires 
a brand made by rolling in corn husks the leaves of a 
certain herb which they cultivated. He also reported 
that they perfumed themselves with the leaves of this 
herb, and that no treaty of peace could be ratified among 
the Indians without smoking the herb in a pipe, because 
they believed that when the smoke of its burning as- 
cended to heaven the Great Spirit smelled a sweet savor 
and was pleased. 
The use of this Indian herb became popular in England 
through the influence of Sir Walter Raleigh, and the 
custom of using it spread rapidly through Europe in 
the seventeenth century. At first it was thought to have 
medicinal value, but in a short time men of intelligence 
and high position came to think of it as a dangerous 
drug and became alarmed as to the consequences that 
409 410 
PRIMER OF PHYSIOLOGY 
would follow its widespread use.1 A great movement 
against the new custom then sprang up over all the 
known world. In Turkey the pipes of smokers were 
thrust through their noses; in Russia the noses of 
smokers were cut off, and those who repeated the offense 
were put to death; the church threatened the users of 
the weed with excommunication; and King James of 
England issued a protest against its use, in which he 
declared it to be “ a custom loathsome to the eye, hate- 
ful to the nose, harmful to the brain, dangerous to the 
lungs, and in the black, stinking fume thereof nearest 
resembling the horrible Stygian smoke of the pit that is 
bottomless.” 
Why the habit of using tobacco is so widespread. In 
spite of all the opposition that has been offered to it, 
tobacco is now used over practically the whole world. 
In the United States the people spend for it more than 
four hundred millions of dollars yearly. Of course, 
if people spend their money in this way, it means 
that they will be compelled to go without food, clothing, 
furniture, books, music, and other things that for their 
health, comfort, and richness of life they ought to have; 
it means millions of extra years of labor for a people 
who are already overworked. In India all ages and 
both sexes are constant smokers, and in China girls of 
eight or nine years wear as a part of their dress a silk 
1 During the seventeenth century the plague, or “Black Death,” 
ravaged Europe, and it was generally believed that smoking was a safe- 
guard against this disease. It is possible that there was some foundation 
for this belief; for the plague is spread by fleas that come from plague- 
infected rats, and it may be that fleas dislike the odor of tobacco that is 
present on the clothes and skin of tobacco users. TOBACCO 
411 
pocket to hold tobacco and a pipe. Yet in India and 
in China the great mass of the people toil for a miserable 
wage that will hardly keep them alive, and in years of 
crop failure hundreds of thousands of them actually 
perish for lack of food. 
Why do men put this extra burden on themselves ? 
Why did the Indians that Columbus saw perfume them- 
selves with the odor of tobacco ? Why do men now 
engage in the seemingly foolish custom of drawing 
smoke into the mouth and puffing it out again ? Let 
us search out the answer to this problem. 
Nicotin. There are certain drugs that produce such 
pleasurable effects on the mind that people form the 
habit of taking them to experience these effects. Among 
these drugs may be mentioned hasheesh, which comes 
from Indian hemp and is used by the people of India. 
It produces a kind of intoxication and fills the mind 
with the most brilliant ideas of grandeur and power, 
causing the most pitiful specimen of humanity to feel 
himself a very king among men. Alcohol has something 
of this same effect, for it deadens the judgment and the 
critical powers of the mind and causes a person to regard 
his own efforts as brilliant, even when there is no ground 
for a high opinion of what he has done. Opium deadens 
the sensibilities to pain and produces sensations of de- 
licious ease and luxury. Cocain, chloral, and a few 
other drugs produce effects that are pleasant to the 
mind, and men fall into the habit of taking them. The 
most widely used of all these drugs, however, is nicotin, 
which is present in tobacco. The sensations produced 
by it will be discussed in a later paragraph. 
Nicotin a narcotic. Physicians speak of certain drugs 412 
PRIMER OF PHYSIOLOGY 
as stimulants and of certain others as 7iarcotics. Stimu- 
lants quicken the action of the protoplasm of the cells; 
they make the muscles contract more strongly and 
cause the nervous system to conduct impulses better 
and to control the body with a firmer hand. Narcotics 
deaden the nervous system and weaken its action ; they 
slacken the muscles and lessen their strength. Strych- 
nin is a good example of a stimulant. It is given by 
physicians when the heart action flags and when there 
is general weakness and collapse. Opium is an example 
of a narcotic. It is given by physicians to dull the 
senses to pain' and to quiet those whose nervous sys- 
tems have been overwrought. The nicotin that is in 
tobacco is a narcotic, and it is so strong that a few drops 
of it introduced into the mouth will paralyze the nervous 
system and stop the beating of the heart.1 We shall 
now discuss some of the more important effects of 
nicotin on the body. 
The influence of tobacco on growth. There are many 
indications that the processes within the cells that cause 
growth differ from the processes that go on during the 
repair of the protoplasm. That is, in cells and in 
young people that are growing, there are processes 
going on that are not going on in cells and in persons 
1 Tobacco is from i to 4 per cent nicotin. In chewing, only a small 
part of the nicotin in the tobacco is absorbed into the body, and in 
smoking, most of the nicotin is broken into other compounds. It is 
probable that these other compounds produce a large part of the effect 
that follows smoking. That men smoke to obtain the drug effects of 
nicotin and of the compounds that come from the nicotin, and not for 
the physical and mental pleasure of the smoking, is shown by the fact that 
a smoker is not satisfied with tobacco from which the nicotin has been 
extracted. TOBACCO 
413 
that have reached their full size.1 Tobacco seems to 
have an especially evil effect on the processes of 
growth; for without doubt it is most injurious to the 
young. Two young guinea pigs that were made to 
inhale tobacco smoke from the fourth day after birth, 
on the forty-fourth day weighed 174 and 169 grams 
respectively instead of 330 grams, which is the normal 
weight for a guinea pig of this age. One of them died 
on the forty-fourth day, and the other was not subjected 
to further inhalations. At the end of the third month 
this animal weighed only 295 grams. The normal 
weight at that age is 485 grams, so the animal was still 
stunted and far below its normal size. 
So generally is it known that cigarette smoking inter- 
feres with the processes of growth and stunts the young 
that most of our states have laws forbidding the sale of 
cigarettes ’to boys below a certain age. In 1889 the 
Japanese government became alarmed because of the 
small size of some of its citizens, and after an investi- 
gation of the effects of tobacco passed a law which 
was worded thus: “ Smoking of tobacco by persons 
under the age of twenty is prohibited.” Professor 
Seaver of Yale University found that of the young men 
entering Yale during a period of ten years, the smokers 
averaged 15 months older than the non-smokers, and 
that notwithstanding their greater age they were one 
third of an inch shorter and had slightly less lung capac- 
ity. The boy who wishes to become large and strong 
1 By experiments on animals it has been found possible to feed them 
in a way that will keep them alive, but will not cause growth in them. 
I his indicates that the processes of growth and of maintenance are 
different. 414 
PRIMER OF PHYSIOLOGY 
should let cigarettes alone during his growing years, for 
there is every reason to believe that young smokers fail 
to reach their full development either of body or of mind. 
The effect of tobacco on the muscles. As we should 
expect, tobacco weakens and relaxes the muscles. Pro- 
fessor Lombard of the University of Michigan tested 
the strength and endurance of his finger muscles on 
four days on which he smoked five cigars daily; then 
on four days on which he abstained from smoking; 
then again on four days when he smoked as on the first 
days. He found that on the days he smoked, his 
muscles had lost on an average 41 per cent of their 
working power. 
The fact that tobacco softens and slackens the 
muscles was so well known before the days of chloro- 
form that patients were prepared for certain surgical 
operations by giving them tobacco to bring about a 
relaxed condition of the muscles. At the present time, 
it is well known among athletes that smoking lowers 
the strength, and athletes who are in training are not 
allowed to indulge in tobacco. Cigarettes will surely 
kill the baseball pitcher’s speed; they shorten the flight 
of the football player’s punt; and the tobacco user’s 
muscles weaken and fail when the crowning effort .of the 
race comes. 
The effect of tobacco on the nervous system. The 
most serious effects of tobacco are on the nervous sys- 
tem. It interferes with the control of the muscles, and 
it damages the mind, as we should expect a narcotic to 
do. The trembling that may be seen in the hands of 
almost any one who smokes cigarettes to excess shows 
in a very marked way how tobacco interferes with TOBACCO 
415 
the control of the muscles. Because of this effect, 
tobacco users are not good marksmen with the rifle, 
and many of them are unable to do delicate work. The 
following statement by Luther Burbank, the great 
plant breeder and nurseryman of California, illustrates 
this point: 
“To assist me in my work of budding — work that is 
as accurate and exacting as watch making — I have a 
force of some twenty men. I discharge men from this 
force at the first show of incompetency. Some time 
ago my foreman asked me if I took pains to inquire into 
the habits of my men. On being answered in the nega- 
tive, he surprised me by caying that the men I found 
unable to do the delicate work of budding invariably 
turned out to be smokers and drinkers. These men, 
while able to do the rough work of farming, call budding 
and other delicate work ‘ puttering ’ and have to give it 
up, owing to inability to concentrate their nerve force. 
Even men who smoke one cigar a day I cannot intrust 
with some of my delicate work.” 
The effect of tobacco on the mind is even more notice- 
able than its effect on muscular control. A study of the 
grades of 500 boys in private schools shows that the 
grades of smokers were on an average 12 to 15 per cent 
lower than the grades of non-smokers. Another set of 
statistics covering sixteen schools in different parts of 
the country and including 800 boys showed that the 
smokers had fallen on an average 17 to 28 per cent 
behind those who did not use the drug. A comparison 
of 50 smokers and 50 non-smokers chosen at random 
in Kansas State Agricultural College showed that the 
smokers had averaged 28 per cent lower in grades and 416 
PRIMER OF PHYSIOLOGY 
that they had made 74 per cent of all the failures that 
were made by the 100 boys. 
Many other comparisons of the scholarship records of 
tobacco users and non-tobacco users have been made, 
and in every case the tobacco users stand far below the 
others in scholarship. So well known is it that tobacco 
interferes with good intellectual work that many large 
corporations absolutely refuse to take into their employ 
young men who use cigarettes. Judge Stubbs of Indiana 
gives a list of twenty-two great employers who follow 
this rule. The list includes Marshall Field & Co., John 
Wanamaker, and seven great railroads. 
How tobacco affects the mind. Tobacco undoubtedly 
injures the mind, so that the person using it learns less 
rapidly and thinks less clearly. Those who have used 
it for some time have a tendency to become nervous, 
restless, unable to remain still for any length of time, 
and unable to keep their minds concentrated on any 
one subject. As one writer expresses it, “The mind of 
a tobacco user seems to lose its grasp of things.” It is 
probable, however, that the main reason why tobacco 
users fall behind other men in intellectual work is that 
nicotin steals away ambition. Its first effect on the 
mind is to lull it to rest; to make one contented with 
himself and his achievements; to make one satisfied to 
sit and watch the smoke curl upward while other things 
take care of themselves.1 This feeling of ease, comfort, 
and freedom from responsibility is very pleasurable, and 
the tobacco habit is the most common of all the drug 
habits to which man is addicted. In summing up the 
1 “Under the influence of tobacco, thought becomes reverie.” — 
Victor Hugo. TOBACCO 
417 
good or the evil which comes from a habit of this kind, 
however, we must always remember that the world’s 
work must be done, and that when a drug for any rea- 
son interferes with the working powers of a man, some 
one else will probably be compelled to do the work 
which he ought to have done. We must also remember 
in connection with all drug habits that it is important 
to know whether we are to be forced to pay with the 
health of our cells for the pleasurable sensation that 
the drug gives. 
Other effects of tobacco on the body. Dyspepsia is 
very common among tobacco chewers who swallow small 
quantities of the juice and among those who damage their 
nervous systems by excessive smoking. Another effect 
of the continued use of tobacco is to raise the blood 
pressure, which greatly increases the work of the heart. 
Smoking also has a bad effect on the air passages, 
for the hot ammonia and other compounds in the smoke 
frequently cause “ smoker’s sore throat,” and cancer 
of the tongue and throat is more common among 
smokers than among non-smokers. Besides all these 
effects on separate organs of the body, the nicotin has 
a depressing and weakening effect on the body as a 
whole, just as it has an enfeebling and quieting effect 
on the mind. 
The effect of a moderate use of tobacco. In reading 
this chapter you must bear in mind that not all the evil 
effects of tobacco that have been described come at 
once, nor is it possible to observe all of them in every 
person who is a tobacco user. Small doses of any drug 
produce proportionately smaller effects than do larger 
doses, so persons who use tobacco moderately suffer 418 
PRIMER OF PHYSIOLOGY 
less from it than do persons who use large amounts, 
The superintendent of the reform school at Westboro, 
Massachusetts, says, “ All boys sent here have been 
users of tobacco.” The chief probation officer of the 
juvenile court of Washington, D.C., says, “ In dealing 
with more than 16,000 delinquent children of this city 
during the last eight years, I find as a rule that the user 
of cigarettes is a stunt, a weakling in body, mind, and 
morals.” In Chicago, of 2402 cigarette smokers in the 
grades below the high school, only 6 per cent were 
doing their school work well enough to pass. 
These are the effects of tobacco when used to excess 
or when used by the young, and persons who have 
experience with cases of this kind naturally regard 
tobacco as one of the worst enemies of mankind. 
Others who see men all about them smoking and yet 
attending to their work day by day often take the view 
that after all the tobacco habit is of little consequence. 
The truth is that some men are born with more health, 
strength, ambition, and intelligence than others, and 
that one of these strong men, even after using tobacco 
for a long time, may still have more strength and brain 
power than the man who lacked these qualities from 
his birth. 
The question is not, however, whether the strongest 
tobacco user has more strength than the weakest man 
who does not use tobacco. The question is whether the 
strong man is able to use tobacco and at the same time 
realize the full strength of his body and of his mind. 
Everything that we know about the effect of nicotin 
indicates that it is not possible to do this; that it is a 
violent poison to the cells; that if taken into the body TOBACCO 
419 
in large amounts, it will cause death; that if constantly 
taken during the growing years, it has a very disastrous 
effect on development; that in any amount whatsoever it 
has a narcotic effect on the muscles and on the delicate 
cells of the brain ; and that any one who uses it will be 
damaged by it. 
Why a boy should not use tobacco. “Your first duty 
in life is toward your afterself—the man you ought to 
be. So live that he in his time may be possible and 
actual. 
“ Far away in the years he is waiting his turn. His 
body, his brain, his soul, are in your boyish hands. He 
cannot help himself. 
“ What will you leave for him ? 
“ Will it be a brain unspoiled by lust or dissipation, a 
mind trained to think and act, a nervous system true as 
a dial in its response to the truth about you ? Will you, 
Boy, let him come as a man among men in his time ? 
Or will you throw away his inheritance before he has 
had the chance to touch it ? Will you turn over to him 
a brain distorted, a mind diseased, a will untrained to 
action ? 
“ Will you let him come, taking your place, gaining 
through your experiences, hallowed through your joys; 
building on them his own ? 
“ Or will you fling away his hope, decreeing wanton- 
like that the man you might have been shall never be ? 
“ This is your problem in life; the problem of more 
importance to you than any or all others. How will 
you meet it, as a man or as a fool ? 
“ When you answer this, we shall know what use the 
world can make of you.” — David Starr Jordan. 420 
PRIMER OF PHYSIOLOGY 
Tell of the discovery of tobacco and its introduction into 
Europe. What different opinions were at first held about to- 
bacco? Name some drugs that are commonly used for their 
pleasant effects. What effect has a stimulant? a narcotic? 
Is nicotin a stimulant or a narcotic ? 
At what time of life is tobacco especially injurious? De- 
scribe the experiment in which young guinea pigs were made 
to inhale tobacco smoke. Why do most of our states prohibit 
the sale of cigarettes to young persons? Give the results of 
Professor Seaver’s observations on students in Yale University. 
What effect has tobacco on the muscles? Describe the 
experiment performed by Professor Lombard. For what pur- 
pose was tobacco used by physicians before chloroform was 
known? Why are athletes in training not allowed to use 
tobacco ? 
What effect has tobacco on the nervous system ? Why are 
users of tobacco not good marksmen ? Repeat what Luther 
Burbank said about his workmen. Give statistics showing 
mental progress made in schools by smokers and by non- 
smokers. What rule have many great employers made regard- 
ing cigarette smokers? How does tobacco affect the mind? 
the digestive system? the arteries? Discuss the effect upon 
the body of a moderate use of tobacco. 
QUESTIONS 
SUGGESTIONS TO THE TEACHER 
If possible, teach this chapter in an informal manner, discussing 
local conditions when it is possible to do so. Statistics as to the 
use of tobacco by the athletes and high scholarship students of the 
school may quickly be gathered, and the attitude of local employers 
may sometimes be mentioned. The continued use of cigarettes by 
the young can only be ascribed to ignorance concerning the results 
of their use, and the question will form an excellent subject for dis- 
cussion at a parents’ meeting. The Scientific Temperance Journal TOBACCO 
421 
Boston, Massachusetts, prints much information on this subject that 
is of value to the teacher. The price of this journal is 60 cents 
a year. 
Emphasize again the importance of forming correct habits and 
how tobacco interferes with the formation of habits of industry. In 
case a good student has recently begun the use of tobacco, call his 
attention to the fact that his previously formed habits of study are 
still keeping his class standing high, but that he should be on the 
alert for signs of the drop in his scholarship record that will in all 
probability come if the use of tobacco is continued. An interesting 
side topic is the early history of the use of tobacco in Europe. The 
securing of the concessions for its sale by Sir Walter Raleigh and 
his efforts to extend its use so that his revenues from it might be 
increased, have much of human interest in them. CHAPTER TWENTY-ONE 
ALCOHOL 
A standard text on hygiene that was used in many 
of our medical colleges as late as 1890 taught that 
malaria was due to miasma from swamps; that typhoid 
fever was connected with the rise and fall of ground 
water; that cholera seemed to be related to the tem- 
perature of the soil from four to six feet below the 
surface; that erysipelas was due to impurities in the 
air; that diphtheria was caused by sewer gas; and that 
yellow fever was an air-borne disease. 
These ideas seem strange to us today, but the fact 
that they were current so recently even among medical 
men emphasizes the fact that in the past men have 
looked upon disease as something that comes upon us 
from without; that they have thought of the causes of 
sickness as lying in the world about us. Now we have 
come to understand that the causes of ill health are to 
be sought for, not in the swamps and forests and changes 
of weather, but within the body itself; that it is what 
goes into the body rather than the distant outside world 
that is important in hygiene. We have learned that the 
great secret of health is to keep the lymph in which the 
cells are bathed free from poisons and impurities and to 
allow the cells to live their own lives in a natural way. 
Along with this new knowledge there has come a 
truer understanding of the uses of medicines and a 
greater care about taking into the lymph strong drugs 
whose effects on the delicate cells are not fully under- 
stood. The best physicians now realize that all medi- 
cines are foreign and unnatural substances in the lymph, 
which ought to be given only when there is good reason 
422 ALCOHOL 
423 
to believe that the body will be benefited by them; and 
they are continually amazed at the reckless and ignorant 
way people pour patent medicines and other strong 
drugs in upon their cells. In this chapter we shall 
study the effects on the body of the use of alcohol, a 
powerful drug that is extensively used by the people of 
our country. 
Where alcohol comes from. Yeast is a small plant that 
lives on the skins of fruits and in very rich earth, and 
that often blows about in the air. The favorite food of 
this small plant is sugar, and when it falls into a liquid 
that contains sugar, it grows and multiplies very rapidly. 
In doing this it uses the sugar for food and breaks it up 
into water, carbon dioxid, and alcohol. This process is 
called fermentation. The alcohol in all the different 
kinds of intoxicating drinks that are used by man comes 
from the fermentation of sugar by yeast. 
Different kinds of alcoholic drinks. The natives of the 
tropics cut off the flower clusters of palm trees and col- 
lect the juice that pours out from the cut ends. This 
contains much sugar, and after it has been fermented 
it contains great quantities of alcohol. The Mexicans 
collect the juice of the agave, or century plant, in the 
same way and manufacture an intoxicating drink from 
it. Fruit juices are rich in sugar, and in temperate 
countries the people make wine by allowing them to 
ferment. Grapes, apples, currants, and blackberries 
are the fruits that are most commonly used for this 
purpose. In the manufacture of beer, grain is soaked 
in water until it sprouts, and the starch in it is digested 
to sugar and dissolved out in water. Yeast is then 
allowed to change the sugar in the liquid to alcohol. 424 
PRIMER OF PHYSIOLOGY 
Rum is made by fermenting molasses and distilling off 
the alcohol; whisky is made by distilling the fer- 
mented liquid from sprouting grains; and brandy is 
made by distilling fermented fruit juice.1 Alcoholic 
drinks have different tastes, according to the substances 
from which they are made, and some are stronger than 
others, but in all of them it is the alcohol itself that 
is the important thing. 
The use of alcohol injurious to the body. Is alcohol 
injurious to the body? In the past there has been 
a division of opinion on this point. Today we have 
come into an age of science, and we are substituting 
knowledge for guesswork in all fields of human thought. 
What are the facts in this case ? Does taking alco*hol 
among the cells cause the body machine to run a longer 
or a shorter time, and is it laid up for repairs more days 
or fewer days in a year when alcohol is used ? The 
following statistics will give us some information on the 
question. 
The effect of alcohol on health and length of life. In 
Australia the workmen have benefit societies that pay 
wages for time lost on account of sickness. The records 
of these societies show that the members of societies 
that admit only abstainers lose but little over half as 
much time on account of illness as do the members 
of societies that admit drinkers. This indicates that the 
use of alcohol increases sickness. A number of life in- 
1 In distilling liquors, the liquid (the fruit juice or the water in which 
the grain has been soaked) that contains the fermented sugar is heated, 
and the vapor that comes from it is caught and condensed. The alcohol 
in the liquid is changed to vapor more easily than water, and the liquors 
that are manufactured in this way are strong in alcohol. ALCOHOL 
425 
surance companies have kept records of the deaths of 
the abstainers and drinkers among their policy holders 
separately. When these records are examined, the 
results are always the same, — the death rate among the 
drinkers is higher than it is among the abstainers. The 
following examples taken from recent reports of insur- 
ance companies will illustrate the point. 
In the ten-year period from September 30, 1900, to 
September 30, 1910, the experience of the Australasian 
Temperance and General Life Insurance Society showed 
that where there were 100 deaths among drinkers there 
were only 62 deaths among abstainers. The Manu- 
facturers’ Life Insurance Company during the nine-year 
period from 1902 to 1910 inclusive had a death rate of 
56 among abstainers as against 100 deaths among an 
equal number of drinkers. For a twenty-eight-year 
period, ending in 1911, the Sceptre Life Insurance 
Association had 67 deaths among its non-drinking policy 
holders, where it had 100 deaths among its non-abstain- 
ing members. All other records that have been kept 
show that there are more deaths among drinkers than 
among an equal number of abstainers of the same age.1 
1 “There may be some actuary in the world who believes that total 
abstainers do not live as long as non-abstainers, but I never heard of one, 
and I have never seen any figures showing an advantage in favor of 
abstainers of less than 21 per cent. Certainly, adding one fifth to a man’s 
life makes it worth while to forego one class of food or drink. 
“ Some years ago I secured an opinion of an actuary on the expectation 
of life of a young man of twenty who was a total abstainer and of one who 
was a drinking man at that age. The expectation of the abstainer was 
42.2 years ; of the drinking man, 15 years.” — Edward A. Woods, an 
insurance manager, quoted in Dr. Henry Smith Williams’ Alcohol: How 
it affects the Individual, the Community, and the Race. 426 
PRIMER OF PHYSIOLOGY 
We can therefore decide that alcohol used as men ordi- 
narily use it causes sickness and shortens life ; and since 
this is true, it must also be true that it is injurious to the 
cells. 
The effects of alcohol on the structure of the cells. 
Alcohol causes fatty degeneration and fibroid degenera- 
tion of certain of the tissues.1 In fatty degeneration 
little droplets of oil begin to collect within the cell, and 
gradually the living protoplasm of the cell is replaced 
by fat, until sometimes the cells become mere bags of oil. 
When the cells of the gastric glands are changed in this 
way, they lose their power to secrete; when the muscle 
cells of the heart are changed to fat, they lose their 
strength ; when the walls of the arteries are affected, 
they are, of course, weakened; and when there is fatty 
degeneration of the liver, kidneys, or nerve fibers, we 
must expect these organs to fail in their work. 
The tissues most commonly affected by fibroid degen- 
eration are those of the liver, kidneys, arteries, heart, 
and brain. In this kind of degeneration there is an 
overgrowth of the connective tissue elements, while the 
working cells degenerate and die. Often in the arteries 
the elastic muscle coat is not only changed to connective 
tissue, but lime is deposited in the walls. These changes 
make “ pipe-stem ” arteries, which are brittle and often 
havf* the opening in them narrowed until it is with great 
difficulty that the blood makes its way through them. 
r As we shall explain later (pages 452-453), there is good reason to 
believe that in some of these changes in the tissues it is intestinal toxins 
rather than the alcohol that really causes the trouble, but since it is the 
drinking of the alcohol that causes the toxins to be formed, the fault in the 
end goes back to the alcohol. ALCOHOL 
427 
Some diseases that may be caused by alcohol. In the 
United States each year there are about 4,000 deaths 
that are directly due to the use of alcohol. Certain 
diseases, moreover, are more commorf among drinkers 
than among abstainers, and it is believed that much sick- 
ness and many deaths are due to accidents and diseases 
that are brought on by the use of alcoholic drinks. 
Prominent among the causes of death that are con- 
nected with the use of alcohol are: hardening of the 
liver, in which the liver turns to connective tissue and 
shrinks into a small, hard organ utterly incapable of 
doing the work which it is supposed to do; diseases of 
the kidneys, in which these organs degenerate and fail 
in their work of excreting the poisonous wastes; heart 
disease, which may take many forms; hardening of the 
arteries; apoplexy and paralysis, which are due to the 
bursting of blood vessels in the brain; insanity and 
other diseases of the nervous system ; tuberculosis, pneu- 
monia, and other germ diseases, to which the user of 
alcohol falls a victim because he has weakened the 
defenses of his body; and accidents that would never 
have occurred had not some one been under the influ- 
ence of drink. 
It will be noticed that the chief effects of alcohol, 
aside from those on the nervous system, are on the heart, 
blood vessels, lungs, stomach, liver, and kidneys, — the 
great internal organs that supply the body with food 
and oxygen and dispose of its wastes. When we re- 
member how the life of the whole body requires that 
the work of these organs be efficiently performed, it is 
easy for us to understand that anything that injures 
them is of first importance in the realm of health. 428 
PRIMER OF PHYSIOLOGY 
The effects of a continued moderate use of alcohol. 
It should be understood that, except for certain effects 
on the brain, we are discussing in this chapter the 
effects of what is called moderate drinking on the body ; 
for when alcohol is used day after day, even though it 
be used very moderately, there is a piling up of its 
effects on the tissues. Indeed, the cells of the man 
who drinks a moderate amount of beer or wine daily 
are never free from the influence of alcohol. Beer 
drinkers suffer most of all from fatty degeneration of 
the tissues, and one need never become intoxicated to 
experience the evil effects from alcohol that have been 
described above.1 The shortening of life given on 
page 407 is in moderate drinkers and not in drunkards; 
for the death-rate among those who habitually drink 
to intoxication is so high that no insurance company 
will accept them.2 
The effects of alcohol on the mind. Because alcohol 
causes a person to seem lively and to talk more easily, 
it is commonly believed that it is a stimulant. This is a 
mistake. Alcohol is a narcotic, and it produces its 
seemingly stimulating effect by paralyzing the higher 
1 “ Alcoholic diseases are certainly not limited to persons recognized as 
drunkards. Instances have been recorded in increasing numbers in 
recent years of the occurrences of diseases of the circulatory, renal, and 
nervous systems, reasonably or positively attributable to the use of alco- 
holic liquors in persons who never became really intoxicated and were 
regarded by themselves and others as * moderate drinkers.’ ” 
— Dr. William Welch. 
2 A few of those classed as drinkers may have become heavy drinkers 
after they were insured, but insurance companies reject not only drunkards, 
but also those who seem likely to become drunkards. The comparison is, 
therefore, in the main between abstainers and moderate drinkers. ALCOHOL 
429 
centers of the brain and allowing the person to do and 
say things that ordinarily his good sense keeps him 
from doing and saying. In one set of experiments it 
was found that 20 to 40 grams of alcohol (the amount in 
from one to two quarts of beer) taken on twelve suc- 
cessive days lessened the capacity to add numbers 40 
per cent and the ability to memorize poetry 70 per cent. 
Other experiments show that the capacity to think 
clearly and to judge correctly is greatly influenced by 
even small quantities of alcohol. Typesetters who were 
given only a little over an ounce of alcohol a day did 
10 per cent less work and made 25 per cent more mis- 
takes than on days when no alcohol was taken, and the 
effect of these small doses of alcohol continued 48 hours. 
After taking a drink, a man feels that his mind is 
working better and that his ideas come more easily and 
freely. The truth is that his mind is slower and his 
ideas are less sensible than usual, but the powers of his 
mind by which he judges of these things have been 
deadened by the alcohol, and he is no longer capable 
of forming a correct opinion of his own acts. 
The effect of alcohol on the strength and control of the 
muscles. The man who has taken alcohol always feels 
that he is stronger and has more endurance because of 
it. In this case, again, the alcohol user is mistaken as 
to his real condition, as facts like the following prove: 
About sixteen years ago, Professor Durig, a chemist 
and an expert mountain climber, carried on a series 
of experiments by repeatedly climbing a peak in the 
Alps. On certain days he drank alcohol equal to the 
amount in two glasses of beer; on other days no al- 
cohol was taken. He was accustomed to use moderate 430 
PRIMER OF PHYSIOLOGY 
amounts of alcohol, and he felt that he worked more 
easily on alcohol days, but to his surprise he found that 
on those days he expended 15 per cent more energy 
and required more than one fifth longer to climb the 
mountain. Other tests carried on for ten days in the 
laboratory showed that two glasses of beer taken at 
dinner reduced the working power of the muscles 10 
per cent. “ Alcohol gives, not strength, but only a 
feeling of strength, to the muscles.” It deadens the 
ability to feel fatigue, but does not relieve fatigue. 
It is probable that the weakening effect of alcohol on 
the muscles is mainly due to its interference with their 
control by the nervous system. The movements are 
made awkwardly, and the muscles work against each 
other, and so much of their power is lost. This lack of 
fineness of control in alcohol users is shown at once 
in a baseball pitcher, a bowler, a rifleman, or any 
one who does work that requires each muscle to work 
exactly the right amount and at exactly the right 
moment. 
Why alcoholic drinks have been banished from the 
United States. When the Great War came and nations 
were put to the test, practically all those that were 
called on to put forth all their effort restricted the 
manufacture and sale of alcoholic drinks. No argu- 
ment was needed to convince the peoples that the manu- 
facture of intoxicating drinks was a waste of foodstuffs 
and their use a hindrance in the prosecution of the war; 
deep within their consciousness they knew that alcohol 
was an evil. They were shaking off everything that 
would hinder them in the great fight and they knew 
that the use of intoxicating drinks would sap the ALCOHOL 
431 
strength and becloud the minds of those who needed 
clear intellects and strong bodies for the struggle. 
Now that the war is over the people of our own 
country have decided that intoxicating drinks shall be 
sold in it no more. Some of the reasons that moved 
them to this decision have been set forth in this chapter. 
The majority of them were convinced that alcohol is 
injurious to health, morals, and efficiency, and they 
saw no reason why in times of peace any more than in 
times of war an unnecessary burden should be imposed 
on our land. After seventy-five years of discussion of 
the question our people, through their representatives, 
have declared that the time when intoxicating drinks 
can be sold in the United States has passed. This de- 
cision is doubtless wise; the combined judgment of an 
intelligent people on any question with which they have 
long been familiar is usually correct. Once again 
America has led the way, and in time the other great 
nations of the earth will doubtless follow the example 
she has set. 
QUESTIONS 
How is alcohol produced ? How is alcohol made in the 
tropics? How is wine made? How is beer made? Name 
some distilled liquors. 
What effect has the use of alcohol on the health ? Give 
statistics showing its effect on the death-rate. 
Explain what is meant by fatty degeneration. What organs 
may be affected in this way ? What changes take place in 
fibroid degeneration ? What organs are commonly affected 
in this way ? Explain the result of fibroid degeneration of the 
arteries. 
In the United States how many deaths each year are due to 432 
PRIMER OF PHYSIOLOGY 
alcohol ? How many are directly caused by alcohol ? Name 
some diseases that are often caused by the use of alcohol. 
What organs of the body are most affected by the use of 
alcohol ? What effects has moderate drinking on the body ? 
Why is it commonly believed that alcohol stimulates the 
mind? What effect have small amounts of alcohol on the 
power to add numbers ? to memorize ? Describe the experi- 
ment in which typesetters were given small amounts of 
alcohol. 
Explain the effects of alcohol on the muscles. 
In teaching this chapter, nothing is so important as to get the 
facts before the pupils. The two most easily accessible sources 
of facts in regard to the effects of alcohol are Dr. Henry Smith 
Williams’ Alcohol: How it Affects the Individual, the Community, 
and the Race (The Century Company, New York) and the numbers 
of the Scientific I'emperance Journal (see page 420). This journal 
gives, through summaries and abstracts, the results of scientific ex- 
periments in this field and translates articles dealing with the very 
important work that is now being carried on in different European 
countries 
SUGGESTIONS TO THE TEACHER CHAPTER TWENTY-TWO 
ACCIDENTS 
“ In time of peace prepare for war.” In every house 
there should be kept in a small box or drawer certain 
articles for use in case of accident. Among- these arti- 
cles should be soft, worn-out towels; cotton or linen cloths 
three to six inches square; 
rolls of bandages varying from 
one half inch to three inches 
in width and from one to two 
yards in length; a bar of green 
soap; threaded needles, scis- 
sors, and safety pins ; borated 
vaselin ; bichlorid or biniodid 
of mercury disks; powdered 
boracic acid ; and a bottle of 
collodion. Accidents come 
without warning, and having 
these supplies ready may save 
suffering or even life. 
Bandages. Since many small hurts are treated with- 
out the aid of a physician, it is well to understand how 
to put on a bandage neatly, comfortably, and securely. 
When the part that is to be bandaged is of nearly the 
same circumference throughout, the bandage should 
simply be rolled around the part from below upward, 
each turn of the cloth covering two thirds of the one 
below. When the part that is to be bandaged is thicker 
in one part than in another, as the forearm or leg, the 
bandage may be made to lie smooth and flat by revers- 
ing each turn after the first few turns. To reverse a 
bandage, hold it at its lower edge and turn it one half 
Figs. 138 and 139. Showing a 
circular bandage and the method of 
reversing a bandage. 
433 434 
PRIMER OF PHYSIOLOGY 
over towards you. To give a neat appearance, make 
each reverse directly above the one preceding it. The 
figure-of-eight bandage is useful 
about joints. The best way to 
get an understanding of the dif- 
ferent bandages here described is 
to study the illustrations in Fig- 
ures 138 to 143. After two turns 
have been put on, the bandage 
should be firmly stitched, and, 
after the bandage is completed, 
the end should be securely sewed. 
A row of stitches from top to 
bottom, one in each turn of the 
bandage, is of great advantage 
in preventing slipping. Always 
bandage firmly, but never too 
tightly, and use an equal pressure 
throughout the bandage. 
Wounds. It is well that a cut 
should bleed freely, as the blood 
assists in washing out and killing 
any germs that may be in the 
wound. If the cut has been made 
with a clean instrument, it may be 
bandaged without any treatment 
at all, or bandaged after being 
dusted with powdered boracic 
acid. A wound made by an 
unclean instrument should be 
washed with soap and water and treated with powdered 
boracic acid or borated vaselin. If the person must use 
Figs. 140, 141, 142, and 143. 
A reversed bandage and a 
figure-of-eight bandage on the 
hand; a figure-of-eight band- 
age and a reversed bandage 
on the foot. ACCIDENTS 
435 
the injured part in attending to his work, two bandages 
should be put on. The outer one may be changed when 
it is soiled, but unless the wound becomes red and pain- 
ful and has matter in it, the inner bandage should be left 
undisturbed until the injury has healed. 
Deep wounds, such as are made by rusty nails that 
have become soiled by lying about barnyards, are dan- 
gerous, because frequently tetanus germs get into them. 
A puncture or other wound that is so deep that it can- 
not be thoroughly cleansed ought to be treated by a 
physician, who will know whether it is advisable to use 
tetanus antitoxin as a safeguard against danger from 
tetanus germs. 
Bleeding. When blood flows in jets and has a bright 
red color, an artery has been cut. If the blood flows in 
a steady stream, it is a vein that 
has been severed. In either 
case, a physician should be 
called at once. In the mean- 
time, control the bleeding by 
pressing on the vessel with the 
thumbs. The pressure should 
be applied between the wound 
and the heart if the cut vessel 
is an artery ; beyond the wound, 
if the bleeding is from a vein. 
If the physician is long in 
coming, or if the bleeding can- 
not be controlled by pressure with the thumbs, twist 
a handkerchief about the limb, as shown in Figure 144. 
The blood should not be shut off from the limb for 
longer than an hour, as much damage may be done by 
FlG. 144. Checking bleeding 
from a wound. 436 
PRIMER OF PHYSIOLOGY 
depriving the cells of their supply of blood for too long 
a time. 
Blows on the head. A blow on the head sometimes 
ruptures a blood vessel within the cranium and causes 
a blood clot to form on the brain. If a person becomes 
sleepy after such a blow, a physician should be called at 
once. It is well to wake the person occasionally during 
the night after such an injury; for otherwise he may 
sink into unconsciousness without its being discovered. 
Burning clothing. If your clothing should take fire, 
do not start to run. If possible, remove the burning 
garment at once. If this cannot be done, remember that 
a fire cannot burn without air, and that the quickest way 
to put out burning clothing is to lie down and wrap your- 
self in a blanket or rug, or in anything else that you can 
lay hands on. If nothing is at hand that can be used as 
a covering to smother the fire, lie down and roll over and 
over. In any case, lie down so that the flames will not 
come up about your face; for inhaling a flame is often 
followed by very serious consequences. In passing close 
to a fire, as in a burning building, the face should be pro- 
tected if possible by something held before it. 
The treatment of burns. A burn in which the skin is 
only reddened, or in which the blistering is slight, may 
be treated by simply shutting the air away from it. 
A paste made of baking soda and water, or of flour or 
starch mixed with water, is good for this purpose. 
White of egg, vaselin, olive oil, castor oil, fresh lard, or 
cream may also be used to cover a burn. Wet cloths 
wrung out of cold water will help to allay the pain. 
Burns which cover much surface, or small, deep burns, 
should be shown to a physician; for it is not always ACCIDENTS 
437 
possible to tell at first how much damage has been done, 
and the injury may be more severe than it appears 
to be. 
A burn made by an acid should be washed and 
treated with limewater, baking soda, or soapsuds. A 
burn made by an alkali (such as lime, lye, etc.) may be 
treated, after thoroughly washing off the alkali, with 
weak vinegar, lemon juice, sour milk, or buttermilk. 
Apparent drowning. Drain the water from the pa- 
tient’s lungs by catching him under the waist and hold- 
ing him for a few 
seconds with the head 
hanging down. Then 
quickly lay him in 
the position shown 
in Figure 145, with a 
folded coat or blanket 
under his chest. 
Place the hands on 
either side of the back 
over the lower ribs. Throw the weight of thebody steadily 
downward on the hands and drive the air out of the lungs. 
Take the pressure off the body without lifting the hands, 
and allow the air to come into the lungs. Repeat about 
fifteen times a minute. This method sends more air 
through the lungs than any of the methods in which 
the patient is laid on his back, and it has the additional 
advantage that the tongue does not fall back and block 
the throat. 
Rubbing the limbs along the veins toward the heart 
causes the blood to circulate and should be kept up if 
there is a second person to attend to it. Keep the 
Fig. 145. Carrying on artificial respiration. 438 
PRIMER OF PHYSIOLOGY 
patient as warm as possible by covering him with a 
blanket and pouring warm water over him, or by laying 
hot-water bottles about him. A hot-water bottle at the 
head is especially important, but nothing hotter than 
can be borne comfortably by the skin of the elbow 
should be brought into contact with an unconscious per- 
son. When the patient begins to revive, give strong hot 
coffee, or fifteen drops of ammonia in a glass of water. 
Artificial respiration should be kept up for an hour or 
longer if the person does not recover sooner. 
Suffocation. Suffocation may be produced by hanging, 
by choking, or by gas or smoke poisoning. Sprinkle 
cold water on the face; carry on artificial respiration 
as in cases of apparent drowning; and, when the person 
is able to swallow, give stimulants as directed above. 
Fainting. Lay the patient flat on his back, so that 
the blood will flow easily to the head. Sprinkle cold 
water on the face, and give him fresh air. Give strong 
coffee or ammonia as directed above. 
Dangers from electricity. As the use of electricity 
becomes more common, it is more and more frequently 
a source of accidents. Even now many people do not 
seem to know that highly charged electric wires and 
third rails are deadly affairs, and that those who do not 
understand their workings ought not to take chances 
with them. Where a. notice is posted warning the 
public not to cross the track of an electric line, there is 
a reason for the warning, and you should keep off the 
track. When a trolley wire or an electric wire breaks 
and falls to the ground, keep away from it. It is in- 
teresting to experiment with electricity, but you cannot 
afford to begin in this way. ACC I DENTS 
439 
Rescuing a person from an electric wire or a third rail. 
A live wire lying on a person may be safely flipped off 
with a dry board or stick. If the person is lying on 
the wire, the wire may safely be cut with an ax or 
hatchet that has a dry wooden handle. Cut between 
the person and the source of the electricity; on both 
sides, if the source of the electricity is unknown. 
In trying to pull a person off a live wire or third rail, 
great care is necessary or the rescuer will be injured. 
In attempting to do this, unless the ground is very dry, 
one should stand on a dry board, a folded coat, or 
several thicknesses of folded newspapers. A rubber 
mat is better than the articles just mentioned, but it is 
not often at hand. If possible, take hold of the per- 
son through dry cloth or paper, and catch him by the 
clothing without allowing the hand to come into contact 
with his body. Pull him off the rail or wire with one 
quick, firm motion, and if he is not breathing, carry on 
artificial respiration as in cases of apparent drowning. 
A doctor should be sent for as quickly as possible. 
Foreign bodies in the eye. If a cinder or other foreign 
body gets into the eye, do not rub the eye. Keep it 
closed and the tears will often wash the dirt out into 
view so that it may easily be removed. Sometimes 
stretching the upper lid down over the lower lid two or 
three times, or closing the nostril on the opposite side 
and blowing the nose hard, will change the position of 
the object and make it possible to remove it. The inner 
surface of the lower lid may be examined by pressing 
the lid down, and some persons are skillful enough to 
turn the upper lid back over a match or small stick so 
that the offending particle can be wiped off. Only 440 
PRIMER OF PHYSIOLOGY 
clean fingers, clean handkerchiefs, or other clean objects 
should be allowed to touch the eye. After the foreign 
body has been removed, a few drops of boracic acid 
solution is soothing and is useful in safeguarding against 
possible infection with germs. 
Foreign bodies in the nose and throat. Little children 
sometimes push beans, peas, beads, or other objects into 
their noses. Having the child blow the nose will often 
bring these objects out, but if they cannot be removed 
in this way a physician should be called. Do not try 
to remove them with a hairpin or other sharp instru- 
ment. 
When a button, coin, or other object sticks in the 
throat, the child should be seized by the feet, suspended 
head downward, and energetically shaken and slapped 
on the back. Usually this will cause the object in the 
throat to drop out. 
Treatment for swallowed pins and needles. When a 
pin or needle has been swallowed, a large meal of bread, 
potatoes, cabbage, or other coarse foods should be eaten, 
as they will leave a large amount of undigested matter 
to coat the foreign object during its passage through 
the alimentary canal. Never give a laxative under such 
conditions. No anxiety need be felt over swallowed but- 
tons, coins, and other similar objects. 
Frostbite. Keep away from the fire and thaw the 
“ bitten ” part out very gradually by rubbing it with 
snow, or by keeping it bathed in ice water until the 
blood begins to circulate through it again. Suddenly 
thawing the frozen tissues is far more injurious than the 
freezing, and every care should be taken to keep in a 
cool atmosphere until the thawing process is completed. ACCIDENTS 
441 
Ivy poisoning. Dissolve a level teaspoonful of potas- 
sium permanganate crystals in a pint of water and 
bathe the affected parts. Before the skin is broken 
Figs. 146 and 147. The poison ivy is often mistaken for the Virginia creeper. 
The Virginia creeper has five leaves, while the poison ivy has only three. 
the poisonous oil may be partially removed at least by 
thorough washing with strong soap or with alcohol. In 
severe cases a physician should be consulted. 
Poisoning. Bottles that contain poisons should not be 
kept among medicines, and it is well to paste strips of 
sandpaper on such bottles, so that they can be recog- 
nized even in the dark. When a poison is taken by 
accident, a physician should be called immediately. If 
possible, have the messenger tell him what poison has 
been taken, so that the proper antidote may be brought. 
A card with a list of the different poisons and their 
antidotes should be written out, and placed with the 
other articles that are kept for use in case of accident. 
The sooner the antidote is given, the less time will the 
poison have to damage the body, and when one is thus 
prepared, a case of poisoning can often be treated be- 
fore the doctor arrives. 442 
PRIMER OF PHYSIOLOGY 
While waiting for the doctor, give an emetic at once 
to produce profuse vomiting, if the poison is not an 
acid. Good emetics are : mustard and water; salt and 
water; lukewarm water alone and in large quantities ; 
and ipecac. Tickling the throat with a feather or thrust- 
ing the finger into the throat will help to cause vomiting. 
The following list of antidotes for some of the more 
common poisons may be found useful: 
Acids. Give soda, chalk, old mortar, or soap. Oil 
and milk are useful. For carbolic acid use alcohol 
(whisky or brandy will do). Oil or milk should be used 
if no alcohol is at hand. 
Arsenic. This is the poison in Fowler’s Solution, 
Paris Green, and Rough on Rats. Give any medicine 
that contains iron. 
Mercuric chlorid. This is also called bichlorid of 
mercury and corrosive sublimate. Give milk, white of 
egg, or both. Flour or starch with milk and egg is good. 
Phosphorus. Magnesia and chalk in water, and white 
of egg are good remedies. Do not give oil or milk. 
Phosphorus is the poisonous substance on the end of 
matches, and is often found in rat poison. 
Opium, laudanum, nightshade, and jimson weed. Give 
strong coffee or ammonia. Keep the patient awake by 
walking him about, slapping him, or throwing cold 
water over him, if necessary. Give stimulants as di- 
rected under Fainting, on page 438. 
Strychnin. Inhaling chloroform or ether will quiet 
the patient. Give five grains of sodium bromid every 
half hour. Keep the patient away from cold drafts and 
noises, and allow nothing to touch him, as any stimulus 
makes the spasms more violent. ACCIDENTS 
443 
Preventing accidents. The first step in preventing 
accidents is so to arrange the conditions under which 
we live and work that it will be difficult for mishaps to 
occur. In machine shops and factories and on railroads, 
this is rapidly being done. The causes of accidents in 
private homes and on farms should also be removed; 
for many houses are built with dangerously steep cellar 
stairs ; many barn lofts can be entered only by climbing 
rickety ladders; stairways and openings in floors that 
are left unprotected by railings are the cause of many 
falls; and farm machinery is constantly being operated 
in a dangerous and careless way. All these and other 
conditions that cause accidents should be remedied, and 
when this is done the number of accidents is at once 
greatly reduced. 
The other important factor in the prevention of acci- 
dents is the use of intelligence and reasonable care 
when it is possible for carelessness to cause an accident 
to happen. In our cities children are continually run- 
ning directly in the way of automobiles and street cars ; 
drownings occur because of a lack of care in handling 
boats and because persons who cannot swim venture 
into water beyond their depth ; clothing is set ablaze by 
standing too near an open fire ; and automobile acci- 
dents occur because of recklessness in driving these 
machines. Accidents of this kind can only be pre- 
vented by intelligence and watchfulness, and you should 
constantly educate yourself in those habits that prevent 
them. 
More people are injured by falling than in any other 
way, and the most common cause of falls is carelessly 
placed ladders. An ordinary ladder should not be set 444 
PRIMER OF PHYSIOLOGY 
too straight or too slanting, and a three-legged stepladder 
stands more securely than a four-legged one. 
The problem of accidents is more important than is 
generally understood (Fig. 148), as in addition to the 
killed, hundreds of thousands of persons are injured in 
them each year. 
QUESTIONS 
Name some articles that should be kept for use in case of 
accident. Name three kinds of bandages and tell how each is 
put on. Describe the treatment for cuts. Why is a deep 
wound made by an unclean instrument dangerous ? When 
blood is flowing from a wound, how can you tell whether it 
comes from a vein or an artery ? How can the bleeding be 
checked until a physician arrives ? 
Why should a person not be allowed to sleep uninterruptedly 
after a blow on the head ? If your clothing were to catch fire, 
what should you do ? Describe the treatment of burns. De- 
scribe artificial respiration. When should it be used? In 
addition to carrying on artificial respiration, what else may be 
done in cases of apparent drowning? What should be done 
in cases of suffocation ? What should be done for a person 
who has fainted ? 
Tell how a person may be rescued from a live wire or a 
third rail. How may foreign bodies be removed from the eye ? 
from the nose ? from the throat ? What is the treatment for 
swallowed pins and needles ? for frostbite ? for ivy poisoning ? 
Give antidotes for the following poisons: carbolic acid; 
arsenic ; mercuric chlorid ; phosphorus. Give the treatment 
for a case of strychnin poison. In what two ways can 
accidents be prevented. OTHER CONSTITU- 
TIONAL DISEASES 
25,334 
CANCER 
*41.039 
DISEASES OF STOMACH 
9,766 
PYOGENIC 
INFECTIONS 
# 28.959 
DISEASES OF 
LIVER 
0,029 
DIPHTHERIA 
:g'll,52l 
DISEASES 
OF OTHER| 
v DIGESTIVE 
I 18,122 J 
WHOOPING 
.COUGH 
!/ 6 ,46 
.MENINGITIS 
L 7,169 
ORGANS 
MEASLES 
6,598 
L/ OTHER 
GERM 
DISEASES 
*54,527 
SCARLET FEVER' 
k 6,255 X. 
DISEASES OF NERVOUS 
SYSTEM 15,365 
ENTERITIS 
(DIARRHEA) 
63,180 
DISEASES OF ARTERIES 
11,657 
APOPLEXY 
- 39.701 
BRIGHTS DISEASE 
47,665 
DIABETES 
-8,040 
DYSENTERY 
3.446 
TYPHOID FEVER 
12.673 
*HEART DISEASE 
80,047 
TUBERCULOSIS 
66,309 
OLD AGE 
13.604 
ALCOHOLISM 
r 2,909 
PNEUMONIA 
79,524 
ACCIDENTS 
45.416 
i CHRONIC \ 
IPOISONINGSA 
X 401 V j 
INFLUENZA 
7.774 
DEATHS DURING 
EARLY INFANCY. 
47,386 / 
BRONCHITIS 
12.620 
SUICIDE 
6.590 
HOMICIDE 
3,190 
FIG. 148. Estimated number of deaths from various causes in one year in 
certain states and cities in the United States. Germs are of more impor- 
tance than the diagram shows, for slow infections of the heart, kidneys, and 
other parts are the primary cause of many deaths listed as physiological 
diseases. Estimates from the 1920 Census reports give about 1,400,000 deaths 
in the whole U. S. A. yearly, 600,000 of which are considered preventable. 
445 CHAPTER TWENTY-THREE 
REALIZING HEALTH POSSIBILITIES 
When a farmer begins to study how to increase his 
harvests, one of the first facts he learns is that it is the 
“limiting factor” that determines what the growth of 
his crops shall be. An exact definition of what a limit- 
ing factor is would mean little either to the average 
farmer or to you, but an illustration makes it easy to 
understand the meaning of the phrase. 
Suppose that in an acre of land there is enough nitro- 
gen to raise 75 bushels of corn, enough phosphorus to 
raise 20 bushels, enough potassium and other needed 
elements to raise 100 bushels, and that the season is 
favorable and there are rain and sunshine enough to 
make 100 bushels. What will the crop be? It will be 
20 bushels. 
The phosphorus is the limiting factor that makes it 
impossible for the yield to rise above that point. A 
chain is no stronger than its weakest link, and it is not 
the half dozen favorable factors, but the one unfavor- 
able one, that determines what the harvest shall be. 
The important thing for the farmer to do, therefore, is 
to find the factor that is limiting his crop and strengthen 
the weak point. Otherwise the abundant supply of 
water and of nitrogen and other plant foods in the soil 
is of no value to him. 
The limiting factor in health. The health of the hu- 
man body is dependent on many different things. All 
of these are necessary, and if kny one of them is lacking, 
it will be the limiting factor that will make health im- 
possible no matter how many other conditions may be 
favorable. One person may have good food, fresh air, 
446 REALIZING HEALTH POSSIBILITIES 
447 
and everything else necessary to health except sufficient 
sleep. In other cases the limiting factor may be the 
condition of the teeth, adenoids, lack of exercise, lack of 
fresh air, alcohol, overwork, or improper food. With 
many persons everything necessary for health is present 
if only disease germs could be kept out of the body. 
In some cases more than one difficulty must, of course, 
be removed before health can be achieved, but often 
only one factor makes the difference between illness 
and health. In our quest for health, it is, therefore, 
most important that we neglect none of the factors 
that are necessary for a realization of our health pos- 
sibilities. To give you some wider ideas that may 
serve as guiding principles in your search for limiting 
hygienic factors in your own life, we shall in this final 
chapter discuss in a more general way the causes of 
sickness and how they may be avoided. 
Two classes of diseases. Diseases may be divided 
into two great classes, —germ diseases and what may 
be called physiological diseases. In those of the first 
class, the difficulty is that germs are growing in the 
body and poisoning the cells. In diseases of the 
second class, the trouble is in the body itself. Some 
organ like the heart or the liver fails in its work and 
the body is like an engine with a broken part. Germ 
diseases are in the main diseases of early and middle 
life, while physiological diseases usually come on only 
in later life when the organs and tissues begin to 
wear out. Figure 148 will give you an idea of some of 
the more important of the diseases belonging to each 
of these classes. 
The cause of germ diseases. Disease germs are 448 
PRIMER OF PHYSIOLOGY 
either bacteria, which are very small plants, or they are 
little animals that live in the body. Like other living 
things, germs must have food, and they grow in the 
body because in it they can find the food supply and 
the warmth that they need. Unfortunately for both 
them and us, however, disease germs produce toxins in 
their bodies that poison our cells. These toxins throw 
out of order all the life processes of the cells, and in 
some diseases like diphtheria and scarlet fever the cells 
in vital organs like the kidneys and the heart may in a 
very few days become soft and mucilage-like, and many 
of them may undergo fatty degeneration (page 426). 
From the diagram on page 445 you will see that germ 
diseases are responsible for practically one half of all 
the deaths in the United States, and they do even more 
damage than this indicates ; for an attack of diphtheria 
at ten years of age may weaken the heart until it will 
fail when the person reaches fifty years of age, scarlet 
fever in childhood may start trouble in the kidneys that 
will lead to Bright’s disease in later life, and it is a com- 
mon thing for typhoid fever to wreck the health for all 
time. Insurance companies that have tried issuing 
policies on the lives of reformed drunkards have found 
the death rates exceedingly heavy. Even when the 
drinking is stopped, the effects of the alcohol that has 
been consumed in years past cannot be removed. So 
even though a person is not killed outright by an attack 
of germ disease, it is nevertheless true that his cells 
are often damaged by the toxins until they never re- 
cover. Germ diseases, therefore, are of far more impor- 
tance than the mere number of deaths caused by them 
shows. REALIZING HEALTH POSSIBILITIES 
449 
How the body resists disease germs. For our resist- 
ance to many germs, we depend on the white corpuscles 
of the blood, which swallow the germs and destroy them. 
At times the corpuscles are very active; at others they 
seem to lose all interest in germs and lie inactive when 
the germs are growing all about them. It has been 
found that this difference in the activity of the cor- 
puscles depends on whether or not there are opsonins 
in the blood. What these are or where they come from 
is not known exactly, but in some way they seem to 
make the germs more appetizing to the corpuscles and 
cause the corpuscles to take them in. There is a differ- 
ent opsonin for each different kind of germ, so that one 
may have plenty of opsonin for the tuberculosis germ, 
and little opsonin for the pneumonia or the grip germ. 
In other diseases the germs are killed in the body 
by a germicidal substance which is formed in the cells 
and appears in the lymph and the plasma of the blood. 
This dissolves and kills the germs, and is even more 
important as a defender of the body than are the white 
corpuscles. As in the case of the opsonins, there 
is a different germicidal substance for each different 
kind of germ that is killed in this way. After certain 
diseases the germicidal substances remain in the blood 
for years or even for life, and we usually suffer from 
these diseases only once. 
The relation of good health to disease germs. The 
power to resist germs depends on having in the blood 
opsonins and germicidal substances for the germs. 
These are naturally present in the blood of the average 
person only in very small amounts, and merely being in 
good health does not seem to increase these amounts. 450 
PRIMER OF PHYSIOLOGY 
If, however, germs are introduced into the body, the 
presence of the germs causes the body to begin the manu- 
facture of opsonins and germicidal substances to com- 
bat them. 
The way to secure immunity to a disease, therefore, 
is to have the disease, or to introduce into the body 
weak or dead germs of the kind that causes it. This is 
what is done in vaccination for smallpox, typhoid fever, 
plague, boils, catarrh, and a number of other diseases. 
We cannot secure this immunity through good health 
alone, as is proved by the fact that diseases like measles, 
typhoid fever, cholera, plague, smallpox, and diphtheria 
attack the strong as readily as they do the weak.1 
It must not be concluded from the above, however, 
that care of,the body is of no importance in dealing 
with germ diseases. It is true that we cannot depend 
on good health to keep us from taking these diseases, 
but after we have them the body has the task of manu- 
facturing enough opsonins and germicidal substances to 
kill the germs. 
It is reasonable to suppose that a vigorous, healthy 
body can do this more rapidly than can a feeble body, 
1 There is a widespread notion, even among physicians, that if one 
will keep himself in good condition he will be able to “ throw off ” any 
dangerous germs that may get into his body. Unfortunately, this theory 
does not seem to be in accordance with the facts. Studies made on the 
soldiers who contracted typhoid fever in the camp at Chickamauga during 
the Spanish-American war showed that these men were no weaker than 
those who escaped the disease, nor were they sick or out of condition 
before the fever came upon them. Laboratory tests show that only about 
one fourth of the rats of San Francisco are susceptible to plague. There 
is no reason to believe that the animals that take the disease differ in any 
way from those that escape it, except in their lack of the germicidal sub- 
stance which kills the plague germ. REALIZING HEALTH POSSIBILITIES 
451 
and even though a strong body does not protect us 
from acute infections, it ought to withstand the strains 
of illness better than a body that has been weakened 
through lack of care. Moreover, in slow diseases 
like tuberculosis, catarrh, bronchitis, chronic colds, ma- 
laria, and chronic infections of many kinds, the body 
has plenty of time to manufacture its protecting sub- 
stances, and a vigorous condition of the health is of the 
highest importance in helping us combat ailments of this 
kind. 
Nevertheless, it remains true that the way to avoid 
germ diseases is to keep the germs out of the body; 
that as long as germs are allowed to be scattered about 
they will find millions of victims who cannot resist 
them ; that the great victories for health that have been 
won in recent years have been won mainly by prevent- 
ing the spread of infectious diseases, and that more can 
yet be done for the health of the world by fighting 
germs than in all other ways combined. 
Physiological diseases. The causes of many of the 
ailments classed as physiological diseases on page 445 
are not well understood; some of them, like cancer, may 
yet prove to be germ diseases; others are due to wrong 
chemical changes in the body that as yet we cannot 
remedy; a third great group of the most important of 
them are connected with the degenerative changes in 
the tissues described on page 426, and with other kinds 
of degeneration which we shall not attempt to explain. 
These degenerative changes take place most fre- 
quently of all in the walls of the arteries and in the 
tissues of the kidneys and heart. Because of their 
great importance and because there is hope that in a 452 
PRIMER OF PHYSIOLOGY 
measure at least they can be prevented, we shall discuss 
the causes of these diseases. 
The causes of degeneration of the tissues. The de- 
generative changes in the tissues are to be looked on as 
the wear and tear that takes place in the machine. 
They are the same changes that are found in old age — 
in fact, they are old age. It is probable that anything 
that injures the health of the body in any way hastens 
these changes, and hurries us into old age faster than 
we otherwise should go. The following causes, how- 
ever, are agreed on by most medical men as being di- 
rectly responsible for many of these tissue changes : 
Acute infectious diseases. After severe cases of diph- 
theria, scarlet fever, measles, pneumonia, grip, meningitis, 
typhoid fever, and other infections, degenerative changes 
have been found in the arteries of even young children. 
With the knowledge that we now have it is possible to 
prevent practically all of our acute diseases, and every 
one ought to be protected from them. 
Chronic infectious diseases. In the diagram on page 
445, heart disease, Bright’s disease, and diseases of the 
arteries are shown as physiological diseases. It would 
perhaps be better to call them germ diseases; for in 
recent years it has been found that nearly all cases of 
them are caused by slow-growing varieties of germs. 
The two great methods of defending ourselves against 
these diseases are to give attention to the teeth, tonsils, 
nasal sinuses, or other parts where the germs have made 
a permanent home, and to live a hygienic life so that 
the resistance to the germs will be built up. 
Intestinal toxins. These toxins when injected into 
the blood of animals cause the degenerative changes in REALIZING HEALTH POSSIBILITIES 
453 
the tissues which we have described. There is little 
doubt that when they are absorbed into the blood from 
the intestines they have the same effects, and that they 
are one of the greatest of all causes of the diseases 
that we are discussing. 
Alcohol. Users of alcohol suffer exceedingly from 
these changes in the arteries, kidneys, and heart. The 
effect of the alcohol often shows itself but little until 
middle life, when the drinker suddenly finds that the 
organs which must keep up the circulation of his blood 
and excrete the poisons from his body have already 
reached old age (see footnote, page 425). 
The possibilities of health and long life. Ninety-five 
per cent of all human beings come into the world with 
sound and healthy bodies. Is it necessary that these 
bodies shall suffer from disease ? There are prophets 
of health who look forward to the day when men shall 
pass from birth to old age without sickness or pain. Is 
it necessary that our cells and tissues shall grow old and 
wear out ? Probably, yes, but with proper care of the 
body the passage of time works comparatively slight 
changes in the tissues and with the knowledge that we 
now have it would be possible to extend the average 
life far beyond the limit that it has yet reached in the 
most advanced countries in the world. 
Within the lifetime of men and women who are now 
at middle age, more has been done to free mankind from 
the bondage of disease than was accomplished in all the 
previous history of the world. Still greater hygienic 
discoveries are almost in sight ahead of us, and no one 
can estimate the health possibilities that lie before the 
boys and girls of today. Three hundred years ago the 454 
PRIMER OF PHYSIOLOGY 
average human machine in Europe lasted twenty years ; 
today it lasts forty years ; intelligently cared for accord- 
ing to the knowledge that we now have it would prob- 
ably last seventy years. To what limit new hygienic dis- 
coveries and careful hygienic living will extend the life 
of this wonderful machine, the future alone can reveal. 
QUESTIONS 
Explain what is meant by the limiting factor in crop raising. 
Discuss the limiting factor in health. Into what two classes 
may diseases be divided ? What is the trouble in each case ? 
Name some of the more important diseases belonging to each 
class. 
What are disease germs ? How do they injure the body ? 
What proportion of the deaths in the United States is due to 
germ diseases ? What additional damage is often done by 
them ? 
In what two ways are we protected against germs ? What 
are opsonins? How may the amount of an opsonin or of a 
germicidal substance in the blood be increased ? What is 
done in vaccination ? 
Is good health sufficient to protect against germ diseases ? 
Give some facts supporting your answer. Why does a strong 
condition of the body assist in recovery from germ diseases ? 
In what kind of germ diseases is the general health of the body 
especially important ? What is the only method of avoiding 
germ diseases ? 
What organs of the body are most often affected by degen- 
erative changes in the tissues ? Give four causes of these 
changes. 
How to Live (Funk & Wagnalls), authorized by the Hygiene Ref- 
erence Board of the Life Extension Institute, Inc., and prepared by 
Fisher and Fisk, gives the best available discussion of the topics 
treated in this chapter. 
SUGGESTIONS TO THE TEACHER CHAPTER TWENTY-FOUR 
FURTHER FACTS CONCERNING HEALTH 
Some yeats ago a man who at times felt dull and un- 
fit for work went to the hospital of a great medical school. 
He told the physicians there that he had followed all the 
ordinary rules of hygiene; that he was careful as to his 
diet, slept regularly, and had been examined by several 
medical specialists to see if his eyes, tonsils, or teeth needed 
attention. No change in his manner of living improved 
his health, and none of the physicians to whom he had 
gone had been able to find anything the matter with 
him. The hospital physicians examined him, and they 
also failed to locate the trouble. They told him that 
the causes of some cases of ill health were not yet under- 
stood and that until the science of medicine made fur- 
ther advances they could do nothing to aid him. 
Are there, then, persons who will not have good health 
even if they follow all the rules of hygiene that we know ? 
Yes, there are such persons; not many of them, but a 
few. They are persons whose bodies do not work in a 
normal way, and the ordinary rules of health do not 
apply to them. Each year, however, the science of 
medicine is advancing, and each year some of these 
seemingly causeless cases of ill health are being explained. 
In this chapter some of the newer facts and ideas relating 
to health will be discussed. 
The chemical regulation of the body. Turn back 
and read again pages 224 and 225. Then as you study 
this chapter remember that the whole world of a cell is 
the lymph about it and that it is what is in the blood and 
lymph that determines whether the cells shall have 
455 456 
PRIMER OF PHYSIOLOGY 
health. Recent studies emphasize this idea more and 
more. Not only is there a regulation of the body by the 
nervous system, but there is also a chemical regulation of 
the body by the blood and lymph. Some of the regulat- 
ing substances, like the vitamins, come from outside the 
body; others are produced within it. Many of the mys- 
teries of physiology and medicine are being explained by 
the presence of materials (often in exceedingly small 
amounts*) in the blood and lymph, or by the absence of 
certain substances that are normally supplied. 
THE DUCTLESS GLANDS 
The names of a number of the ductless glands and their 
location in the body may be learned from Figure 149. 
Like all glands, these organs take materials which come 
to them and build them up into new products. But these 
glands have no ducts as other glands have. The sub- 
stances that they build simply soak out through the 
walls of the gland cells into the lymph and are carried 
all through the body by the blood. 
The thyroid gland. The thyroid gland lies on the 
front and sides of the trachea below the larynx. If in 
infancy its secretion is lacking, growth and development 
do not take place as they should; the person becomes a 
1 The smallness of the amounts of many important substances in the 
body is quite astonishing. In all the blood there is only a small teaspoon- 
ful of sugar, a tablespoonful of salt, three fifths of a grain of iodin (equal 
to three fifths the weight of a grain of wheat), and one to three grains of 
urea. Vitamins and enzymes are present in unbelievably small amounts, 
and if an ounce of epinephrin were diluted in enough water to fill a pro- 
cession of city sprinkling carts sixteen miles long, the tests that the 
physiologist uses would still detect it. FURTHER FACTS CONCERNING HEALTH 
457 
Fig. 149. Diagram showing the location of some of the ductless glands in the 
body. The thymus in early life is larger than most of the other ductless 
glands. Little is known of its function or of that of the pineal gland, while 
the function of the carotid glands is quite unknown. The effects of the secre- 
tions of the other glands shown in the drawing are discussed briefly in the 
text, but the whole subject is so new that our knowledge of it is very in- 
complete. 458 
PRIMER OF PHYSIOLOGY 
dwarf and often an imbecile. If in later life the thyroid 
fails to secrete sufficiently, the skin becomes thick and 
dry and the hair tends to become dry and to fall out. 
Food is not oxidized as rapidly as is normal if the thy- 
roid secretion is insufficient. This causes a tendency to 
fatness. The person is sensitive to cold, his mind is 
dull, and it is believed that his resistance to disease 
germs is low. Physicians treat this disease both in 
young children and in older persons by feeding extract 
of the thyroid glands of animals and in this way secure 
very remarkable results. The first patient so treated 
kept in good health for twenty-eight years by con- 
stantly taking the thyroid material. 
On the other hand, the thyroid gland sometimes pro- 
duces its secretion in too great amount.1 This causes 
the ailment known as Graves’ disease, or exophthalmic 
goiter. Among the symptoms of this disease are a rapid 
heartbeat, trembling of the hands, a moist skin, and 
nervousness. In the early stages the patient shows 
great energy and activity. In later stages there is a 
sticking out of the eyeballs, and often the gland is en- 
larged so that it can be plainly seen at the base of the 
neck. More food than normal is oxidized, and in con- 
sequence there is a tendency to thinness and hunger. 
Physicians treat this ailment by removing a portion of 
the thyroid gland or by treating the gland with the 
X-ray. 
In some regions enlargement of the thyroid gland 
1 Some physicians believe that sometimes the difficulty in ductless 
gland troubles is that the glands form the wrong substance, and not 
merely too much or too little of the normal secretion. FURTHER FACTS CONCERNING HEALTH 
459 
(simple goiter) is very common among both people and 
animals, and it has now been discovered that in these 
regions there is a lack of iodin in the soil and conse- 
quently in the crops grown on the land and in the water 
that is used for drinking purposes. If iodin is added 
to the food, the disease is prevented; so this mineral 
is supplied to farm animals and even to the young fish 
in the hatcheries. In some parts of Switzerland where 
goiter is very common, only salt brought from non-goi- 
trous regions, or that has had iodin added to it, is allowed 
to be sold. In one city in the United States iodin is being 
added to the water supply. That the taking of more 
iodin than is naturally present in the food and water is 
in some places advisable, is shown by the results secured 
at Akron, Ohio. Here a large number of school children 
were given small doses of iodin in the spring and fall for 
two and one-half years.1 Of 2190 without signs of 
goiter taking the iodin, only five developed symptoms, 
and of 1182 having symptoms, 773 improved. At the 
same time, other children who did not take iodin were 
examined. Of these, 495 out of 2350 developed symp- 
toms of goiter in the two and one-half years, and of 1048 
having symptoms only 145 improved. 
The parathyroid glands. The parathyroids, usually 
four in number, lie on the back and lower part of the 
thyroid, two on each side. They are flattened, reddish- 
brown bodies, about the size of small beans. When they 
are removed from an animal, convulsions and death soon 
follow. The function of these glands is not definitely 
1 The amount given was two grams of sodium iodid in .2-gram doses 
administered each school day for two weeks. 460 
PRIMER OF PHYSIOLOGY 
known. It has been 
thought that they are per- 
haps concerned in the use 
of calcium in the body, 
but our knowledge of 
them is so scant that it is 
of little or no practical use. 
The pituitary gland. 
This small gland lies on 
the bottom of the brain 
above the pharynx. It 
consists of two parts, a 
front and a back lobe, 
which are composed of 
different kinds of cells 
and which produce en- 
tirely different secretions. 
The front lobe controls 
the growth of the bony 
skeleton. If in childhood 
the secretion from it is low 
in amount, the person will 
not grow and mature in 
a normal way, and if the 
secretion is markedly lack- 
ing, he will be a dwarf. 
On the other hand, an 
overabundance of the se- 
Fig. 150. Two side-show companions. The giant owes his unusual height to an 
overabundant supply of the secretion from the fore lobe of the pituitary gland. 
The small stature of the dwarf, who is about thirty years of age, is due to an 
insufficient supply of this same secretion. FURTHER FACTS CONCERNING HEALTH 
461 
cretion during the growing period causes a person to 
become a giant. An examination of the skull of a giant 
always shows the bony pocket on the floor of the cranium 
in which the pituitary body lies to have been unusually 
large.1 
The secretion from the back lobe of the pituitary body 
seems to influence the use of carbohydrates in the body, 
and probably also to regulate the muscles of the ali- 
mentary canal and blood vessels. If it is low in amount, 
there is a tendency to fatness. There is also a lack 
of energy and life, while on the other hand an abundant 
secretion from the back lobe seems to give vigor and 
endurance both to the muscles and to the mind. In a 
number of persons who have headache the seat of the 
trouble seems to be in the pituitary gland. 
The adrenal bodies. The adrenal glands lie on the 
kidneys, one on each kidney. They are flattened, oval 
bodies, perhaps an inch and a half in length. Like the 
pituitary gland, the adrenals are composed of two dis- 
tinct kinds of cells which give secretions that have wholly 
different effects. 
The secretion from the outer cells (cortex) seems to be 
associated with masculine characters. In boys, when 
the supply is low, the voice changes slowly and the beard 
is scant. When the supply is overabundant, the voice 
may change even at nine or ten years of age and the beard 
start at a very early age. In women a tumor on the 
suprarenal body, which causes an overgrowth of the outer 
1 By X-ray photographs physicians can determine the size of this 
pocket and thus learn whether the pituitary gland in a person is large 
or small. 462 
PRIMER OF PHYSIOLOGY 
cells, causes the development of a beard and produces 
the “ bearded lady ” of the side show. 
The central cells (medulla) of the adrenals produce a 
substance called epinephrin that is now extensively used 
in medicine. It stimulates the heart more effectively 
than anything else known, causes a tightening up of the 
arteries when these are lying flabby and relaxed in cases 
of weakness or shock, and if painted on a wounded sur- 
face will cause the small arteries to contract and check 
the bleeding, in part at least. It also gives strength to 
the muscles. 
This substance can be detected in the blood if it is 
present in sufficient amounts, and it is known that in 
anger or when great effort is made, it is thrown off from 
the glands. Many investigators believe that a constant 
supply of it is furnished to the blood, which keeps all the 
muscles of the body (including the heart and blood vessels) 
in tone. Others believe in the “ emergency theory,” 
that the epinephrin is thrown into the circulation only 
at times when great strength or endurance is likely 
to be needed. It has been suggested that the “ second 
wind ” which comes to the tiring athlete may be due to 
a supply of epinephrin reaching the muscles and giving 
them new power. 
The islands of Langerhans. These are small groups 
of cells that lie scattered through the pancreas and are 
entirely distinct from the cells that secrete the pancreatic 
juice. The cells of these islands produce a substance 
called insulin, that makes the body able to use sugar. 
Without it the sugar is not oxidized by the cells and passes 
off through the kidneys, causing the disease called dia- FURTHER FACTS CONCERNING HEALTH 
463 
betes. Because the group of cells which produce the 
secretion is mixed in among the other pancreatic cells, 
it was impossible until recently to secure from them a 
supply of the insulin in an effective form. Now this 
has been done, and with it physicians are able to relieve 
sufferers from this disease. 
Other facts about the ductless glands. There are a num- 
ber of other ductless glands in the body besides those men- 
tioned. Some of these are known to have great effects 
on the body. Of the function of others, little or practi- 
cally nothing is known. In general, the secretions of 
the ductless glands regulate the processes of the body. 
Fatness or leanness, tallness or shortness, too great 
energy and excitability or dullness and fatigue, voracious 
appetite or little desire for food, baldness or an abun- 
dance of hair, all these may at times be due to the action 
of these glands. Many cases of chronic ill health are 
also due to a lack of a proper balance of their secretions, 
and an understanding of the importance of these glands 
has opened a whole new field of hygiene. 
The whole subject, however, is very complicated, 
and only a physician can give safe advice in any par- 
ticular case. The working of one gland often affects 
others, so that it is difficult to determine which one was 
first at fault. Moreover, too much secretion is very 
commonly followed by a period of too little secretion, 
making it difficult to decide whether at any given time 
the gland is underactive or overactive. Giants, for 
example, who show in their stature the results of too 
much pituitary secretion, usually suffer in later life from 
too little of this secretion. One who imagines that he has 464 
PRIMER OF PHYSIOLOGY 
symptoms of glandular disturbance should not begin 
taking gland extracts without medical advice, for these 
extracts are powerful medicines, and if the wrong ones 
are taken, much injury may be done. 
Causes of trouble with the ductless glands. Goiter 
seems to be often due to a lack of iodin, but our present 
knowledge indicates that the two most common causes 
of other diseases of the ductless glands are infections and 
too strenuous a life. Undoubtedly in diseases like in- 
fluenza, malaria, typhoid fever, diphtheria, and tubercu- 
losis these glands are often injured, probably in many 
cases for all time. In the weak period during recovery 
from these diseases, physicians often prescribe gland 
extracts to help bring the patient back to health and 
strength, and preventing germ disease is doubtless a 
most important step in the avoidance of trouble with 
the endocrine glands. 
The other method of avoiding these troubles is to live 
a quiet, sensible life and not undertake work or other 
activity beyond one’s strength. Worry, anger, fear, 
great effort or strain of any kind, causes an unusual 
amount of secretion to be produced by some of the glands 
at least, and many persons are so constituted that if the 
exciting conditions are kept up the glands in time be- 
come exhausted and fail in their work. Unfortunately, a 
wrought-up nervous system speeds up the glands and 
the glands in turn speed up the nervous system, so that a 
person under strain, instead of stopping for rest, has a 
tendency to keep increasing his pace. The great ma- 
jority of persons must have rest and recreation to keep their 
ductless glands working in a normal way. FURTHER FACTS CONCERNING HEALTH 
465 
SENSITIZATION TO PROTEINS 
If a little sterile milk or white of egg is injected into the 
abdominal cavity of a guinea pig, no harm is done the 
animal. But if a second dose is given it two weeks later, 
it will in a few minutes begin scratching at its mouth 
and have difficulty in breathing, and may even die. It 
suffers from an attack of asthma in which the muscles 
of the small air tubes contract and shut off the air from 
the sacs of the lungs. After the first dose the animal 
becomes “ sensitized ” to the protein used. Just why this 
is true can be explained only in part, but if a “ foreign ” 
protein (one not digested and prepared for absorption 
into the body) gets into the blood, the cells become sen- 
sitized to it. 
It has been discovered that a considerable number of 
persons are sensitive to proteins that they breathe in 
or take in their food. How they become sensitive to 
these proteins is in many cases difficult to explain, but 
they are sensitive, and when the proteins get into 
the system a variety of effects is produced. Some 
of the more practical phases of this question will be 
discussed. 
The skin test for protein sensitivity. Whether a per- 
son is sensitive to any given protein can be determined 
by a simple skin test. A very slight scratch (not deep 
enough to draw blood) is made on the arm, and a little 
of the protein is rubbed into the wound. If the person 
is not sensitive, no reaction follows. But if he is sensi- 
tive, the skin rises in a thick welt (like a “ hive ”) about 
the wound. By a couple of rows of scratches down one 466 
PRIMER OF PHYSIOLOGY 
X, Typical reaction 
Y, Negative control 
Fig. i 5 i . The result of a skin test with horse-hair protein on an asthma patient. 
At the place marked X a scratch on the skin was made and the protein rubbed in ; 
at the place marked Y the skin was also slightly scratched, as for the other test, 
but no protein was rubbed in. 
arm the test for a large number of proteins can be made 
at once, and the offending ones can usually be thus 
picked out. 
After one has learned that he is sensitive to a protein, 
he can then often keep from inhaling it or taking it in 
his diet. If this is not possible, the person can be “ de- 
sensitized ” by a course of vaccination with the protein. 
It must be noted, however, that the skin test probably 
fails in some cases of protein sensitization and that our 
knowledge is not yet sufficient to allow it to be said with 
certainty that vaccination against the sensitivity will 
always succeed. And it should perhaps be noted further 
that, in some cases at least, the vaccination must be re- 
peated at intervals to keep the immunity from being 
lost. 
Hay fever. A considerable number of persons are 
sensitized to wind-borne pollens — the pollens of grasses, 
weeds, and other plants. When these pollens are in the FURTHER FACTS CONCERNING HEALTH 
467 
air, such persons become afflicted with hay fever, which 
resembles a violent cold in the head. As a preventive 
and remedy, the patient can be desensitized by vacci- 
nation with the protein of the pollen that causes the 
trouble. In hay fever there is often an abundant growth 
of bacteria in the affected parts, and it may be necessary 
to vaccinate against these as well as with the pollen. 
Asthma. A large percentage of all persons suffering 
from asthma are sensitive to some protein, and when they 
keep away from this they are not troubled with the 
disease. Sometimes the protein is taken in the food; 
quite often it is inhaled. In many cases the trouble is 
due to dust from horses, the hair from dogs or cats, 
feathers from a pillow, rabbit fur from a couch or mat- 
tress, or even orris root from face powder. 
The first step for an asthma patient is to be tested to 
find the protein to which he is sensitive, unless he al- 
ready knows this. Then, if he cannot keep away from 
this protein, a course of vaccination is in order. 
Like other persons who suffer from chronic ailments, 
asthmatic patients frequently become exceedingly anx- 
ious to be restored and are willing to try anything that 
promises relief. On this account, numerous patent 
medicines for asthma are on the market. Many of them 
contain opium, and of course they can in no way remove 
the cause of the disease. 
Skin troubles from protein sensitivity. An occasional 
person, after eating some article of food (e.g., fish, eggs, 
strawberries), will break out with hives. In other per- 
sons the offending food causes a swelling of the lips and 
tongue or a more or less constant blotchy and itchy 468 
PRIMER OF PHYSIOLOGY 
condition of the skin. Any one with skin trouble can 
well afford to consider whether the cause is not sensi- 
tivity to some food. 
Other troubles due to sensitivity to proteins This 
subject is very new, and our knowledge of it is in- 
complete. We know enough, however, to appreciate 
the truth of the old proverb that “ what is one man’s 
meat is another man’s poison.” There are babies to 
whom cows’ milk is poison. There are persons who are 
made uncomfortable or ill by eating some of our most 
highly esteemed foods. There is evidence that some 
cases of headache and chronic ill health may be due to 
sensitization to proteins that, like those of bread or beef, 
are taken every day in the food. Just what will develop 
in this field the future must tell, but the principles in- 
volved are of wide application. Consumptives react 
to the tuberculin test because they are sensitive to the 
protein of the tubercle bacillus. Other similar tests 
are used in medicine, and desensitization to a protein 
and vaccination are near akin. 
It should be noted that a person who has just come 
through an attack of asthma or hives may for a time be 
immune to the protein that caused it and does not react 
to the skin test, the eating or breathing in of the protein 
seeming to act as a vaccination. The type of headache 
that some physicians believe to be due to protein sensi- 
tivity is the one that comes at intervals and leaves the 
patient in good health for a few days after the attack 
has gone. Some physicians believe that certain cases 
of epilepsy are also due to sensitization to food. FURTHER FACTS CONCERNING HEALTH 
469 
THE EFFECT OF DRUGS ON THE BODY 
In this connection it is of interest to note that many 
mineral and vegetable substances, even in small amounts, 
also have great effects on the body. Arsenic and mercury 
are strong mineral poisons. Strychnia and bella donna 
are examples of poisons from plants. Alcohol, wood 
alcohol, and caffein are other examples of substances of 
vegetable origin that have a marked effect on the body. 
Some drugs are peculiar in that after they have been 
taken a few times there is a tendency to form the habit 
of taking them. Alcohol, tobacco, coffee, and tea are 
the substances most commonly taken habitually, and 
doubtless the world would be better if all these substances 
could be banished from it. Opium, heroin, cocain, and 
morphine are other habit-forming drugs that exert a 
profound influence on the cells. 
The use of these last-named and other similar drugs 
has become a real evil in our country, and it is well that 
every one should understand the dangers connected 
with them. Sometimes persons begin taking them be- 
cause they are in pain or cannot sleep. Sometimes they 
have much work to do and great responsibilities to carry, 
and they take the drug to brace them up for a time. 
Generally the drug is taken thoughtlessly in the begin- 
ning, because it is furnished by some one who hopes to 
fix the habit on the user and later profit by the sale of 
the drug to him. 
The one safe rule to follow in connection with these 
drugs is to let them alone. The secretions of the duct- 
less glands normally belong in the body and are needed 470 
PRIMER OF PHYSIOLOGY 
to keep the natural processes going on in the cells. 
Drugs, on the other hand, are foreign substances that 
throw the body processes out of their natural courses and 
so interfere with or destroy the health. For this reason 
drugs or medicines of any kind should be taken only on 
the advice of a physician, and a physician should be 
careful as to the advice that he gives. 
QUESTIONS 
Give some examples of substances that regulate the body. 
Name some of the ductless glands. What do these organs do? 
Why are they called “ ductless ” glands? 
Where is the thyroid gland situated? What is the effect on a 
young child of not enough thyroid secretion ? on an older person ? 
How do physicians treat these cases ? 
What are the effects of too much thyroid secretion? What 
disease is common where there is a lack of iodin in the soil and 
water? How can this disease be prevented? 
Where are the parathyroid glands located ? the pituitary gland ? 
What effect has the secretion of the front lobe of the pituitary 
gland? of the back lobe? Where are the adrenal bodies? What 
are the results of too much and too little secretion from the outer 
cells of these bodies ? What substance is produced by the central 
cells? How is this used in medicine? What is supposed to be 
its function in the body? 
What substance is produced by the groups of cells in the pan- 
creas ? What effect has this substance on the body ? Why is the 
study of the ductless glands difficult? Why should extracts from 
these glands be taken only on the advice of a physician ? Give 
two causes of trouble with the ductless glands. 
How is a person tested for sensitivity to protein? How is de- 
sensitization carried out? What is the cause of hay fever? of* 
asthma? What treatment is given for these diseases? What 
skin troubles may be due to food sensitivity ? What other troubles 
may be due to this cause ? FURTHER FACTS CONCERNING HEALTH 
471 
Name some mineral or vegetable substances that have marked 
effects on the body processes. Name some habit-forming drugs. 
How is the drug habit usually started? What rule should be 
followed in connection with these drugs? CHAPTER TWENTY-FIVE 
VITAMINS 
Each year our knowedge of vitamins is extended, 
and each year their importance is more and more appre- 
ciated. They have been mentioned in connection with 
foods (page 355), but because a sufficient supply of them 
is so absolutely necessary for health, they will be discussed 
in somewhat more detail at this point. Four of them 
— called, respectively, vitamin A, B, C, and D — are 
now known. 
An interesting fact is that chemical tests indicate that 
perhaps vitamin C is quite closely related to epinephrin, 
and it has been suggested that possibly this vitamin is 
necessary to the body in order that the adrenal glands 
may have the raw material for the manufacture of their 
product. An understanding of vitamins from a chemical 
Fig. 152. Photograph showing the effect of vitamin A on growth. The rats 
are sisters of the same age. Both had the same diet except that the one on the 
right had butter, which furnished it with vitamin A, while the one on the left was 
supplied with other fats which lacked this vitamin. 
National Dairy Council 
472 VITAMINS 
473 
Fig. 153. These chickens are sisters of the same age and the same hatch. After 
hatching, both were fed all the wheat, oats, corn, and millet they would eat. The 
larger was fed milk every day in addition, while the smaller one received no 
milk. The milk supplied amino-acids, vitamins, and minerals not furnished in 
sufficient amounts by the other food. 
National Dairy Council 
standpoint and a knowledge of what they do in the body 
would doubtless be of immense value in hygiene. At 
present our knowledge of them must be gained by feeding 
experiments on animals and by observations of the 
effects of different diets on men. 
Vitamin A. Vitamin A is manufactured in the leaves 
(green parts) of plants. It is found stored in other parts of 
some plants (see pages 355 and 386). The cow takes it from 
the food that she eats and secretes it in the milk, and the 
hen likewise extracts it from her food and gives it to us 
in the yolks of eggs. The amounts in eggs and milk 
vary, however, with the diet of the hen and cow. When 
a cow is on grass, the milk is much richer in this vitamin 
than when she is kept on dry feed. The vitamin content 474 
PRIMER OF PHYSIOLOGY 
Fig. i 54. This miserable-looking rat had before him at all times food that would 
supply everything needed except vitamin B. Each day he ate less and less and 
at the end of a month was about to die. Then he was supplied with the lacking 
vitamin, with the results shown on the next page. 
Connecticut Agricultural Experiment Station 
of the milk of a nursing mother also varies with the diet 
taken. In order that the baby may be sure of having 
enough of vitamin A, the mother should eat green vege- 
tables and use freely butter and milk. 
When animals are given a diet lacking vitamin A, 
growth stops entirely and soreness of the eyes develops. 
When the supply of the vitamin is low, growth is slow and 
the health poor. In parts of South America where the 
people live to a very large extent on meat, eye disease 
due to a lack of this vitamin is quite common. 
Vitamin B. Vitamin B is found in whole grains; in 
beans, peas, potatoes, turnips, and other vegetables; 
in milk and eggs ;• and in various other foods. In our 
country almost every one secures enough of this vitamin, 
but the lack of it causes a disease of the nervous system 
called beriberi, which is responsible for many deaths in 
some countries. VITAMINS 
475 
In grains, vitamin B is in the surface layers, and among 
peoples like the Filipinos and Japanese, who live largely 
on polished rice, many persons lack a sufficient supply 
of it. Sailors and some of the inhabitants of Labrador 
have also suffered from beriberi because of living on a 
diet composed almost entirely of white bread and salt 
meat. 
Vitamin C. Vitamin C is abundant in oranges, lemons, 
tomatoes, and rutabagas, and in general in fresh vege- 
tables and fruits. The lack of it causes a disease called 
scurvy, in which the joints are swollen and tender and 
there is bleeding of the gums and loosening of the teeth. 
This disease can be prevented by the use of fresh fruits 
and vegetables, and in babies is relieved in a wonderful 
way by giving the juice of oranges, tomatoes, or ruta- 
bagas. Milk is only moderately rich in vitamin C, and a 
baby should have an additional supply of the vitamin 
in orange juice or in some other food. This vitamin is 
Fig. 155. Within a few hours after receiving the vitamin the rat was again 
eating and in 24 hours was running about. A few days later he was in good 
flesh and afterward grew at the normal rate. 
Connecticut Agricultural Experiment Station 476 
PRIMER OF PHYSIOLOGY 
destroyed by heating unless acid is present, and babies 
fed on pasteurized, canned, or dried milk are especially 
likely to lack it. In former times, when ocean voyages 
often lasted for months, sailors suffered greatly from a 
lack of vitamin C. 
Vitamin D. Vitamin D has only recently been dis- 
covered. The lack of it, in connection with a low supply 
of either calcium or phosphorus, or a bad balance be- 
tween the supply of these minerals, causes rickets — 
a disease in which the bones and teeth are soft because 
lime is not deposited in them. It is not known what 
foods supply us with vitamin D. Cod-liver oil will 
cure rickets, and so it must contain the vitamin. It is 
present in egg yolk also, and is probably found in toma- 
toes and green leaves. 
Recent experiments indicate that certain persons have 
soft, defective teeth which decay easily because they 
lack either a sufficient supply of vitamin D or of the 
minerals needed for building sound, hard teeth. It is 
known that tooth decay is practically unknown among 
certain primitive peoples, and it appears that the problem 
of keeping the teeth sound cannot be solved without 
attention to the diet. From our present knowledge it 
seems probable that many persons could greatly im- 
prove the quality of their teeth by eating more green 
vegetables. VITAMINS 
477 
QUESTIONS 
How many vitamins are now known? Where is vitamin A 
manufactured? Name some foods in which it is found. What 
effect has a lack of this vitamin ? 
Name some foods rich in vitamin B. What disease is due to a 
lack of this vitamin ? Where is vitamin C found ? What ailment 
results from a lack of it ? How can it be supplied to babies ? 
What disease is due to a lack of vitamin D ? In what foods is 
this found ? What is the probable cause of soft teeth ? APPENDIX 
Disease 
Infectious 
Material 
Incubation Period 
Early Symptoms 
Time Usually Excluded 
from School 
Scarlet fever 
Discharges from 
mouth and 
nose 
Two to five days 
Vomiting, sore throat, headache, or 
fever. Rash usually appears with- 
in 24 hours on neck and chest 
About six weeks from 
beginning of disease 
Diphtheria 
Discharges from 
mouth and 
nose 
Few hours to seven 
days 
Sore throat with white patches, swell- 
ing of the glands of the neck. In 
nasal diphtheria, lips are often sore 
from discharges from nose 
Until two negative cul- 
tures are obtained 
Measles 
Discharges from 
mouth and 
nose 
Ten to fourteen days 
Cold in head; inflamed eyes, sneezing 
and coughing. Rash first appearing 
on forehead and face about third or 
fourth day 
About three weeks 
Chicken pox 
Fresh or dried 
matter from 
eruption 
Fourteen days 
(eleven to nine- 
teen) 
Fever sometimes mild. Rash on 
second day, developing later into 
crusts 
Until scales and crusts 
have disappeared 
Whooping 
cough 
Discharges from 
mouth and 
nose 
Fourteen days (may 
be shorter) 
Cold in the head, and cough 
Five weeks from begin- 
ning of disease, or until 
the “ whoop ” has en- 
tirely disappeared 
Mumps 
Discharges from 
mouth and nose 
Fourteen to twenty- 
one days 
Slight fever, pain and swelling of the 
jaw 
Four weeks from enlarge- 
ment 
In some cases discharge from the eyes and ears may also be infectious. Incubation periods are often irregular and 
may be longer or shorter than the periods given. 
A. SOME IMPORTANT FACTS IN REGARD TO CERTAIN INFECTIOUS DISEASES 
479 480 
APPENDIX 
B. VITAMINS IN DIFFERENT FOODS 
Name of Food 
Vitamin 
A 
Vitamin 
B 
Vitamin 
C 
Vitamin 
D 
Foods of Animal Origin : 
Beef fat 
+ 
- 
- 
? 
Butter 
+ + + 
- 
- 
? 
Brains . . 
+ 
+ + 
+ 
? 
Cheese 
+ + 
? 
? 
? 
Cod-liver oil 
+ + + 
? 
- 
+ + 
Eggs 
+ + 
+ 
+ 
+ 
Fish fat 
+ 
+ 
? 
? 
Fish roe 
+ 
+ + 
+ 
? 
Honey 
- 
+ 
- 
? 
Lard 
+ 
- 
- 
? 
Liver 
+ + 
+ + 
+ 
? 
Meat, lean 
— to 
+ 
+ 
? 
Milk, raw 
+++ 
+ + 
(variable) 
+ 
evaporated 
+++ 
+ + 
(variable) 
? 
condensed . 
+++ 
+ + 
(variable) 
? 
Foods of Plant Origin : 
Apples 
+ 
+ 
+ 
? 
Bananas 
+ 
+ 
+ 
? 
Beans, navy 
? 
+ + + 
- 
? 
string, fresh 
++ 
+ + 
+ + 
? 
Beets 
? 
+ 
? 
? 
Cabbage (cooked) .... 
+ 
+ + 
+ + 
? 
Carrots (cooked) 
++ 
+ 
+ 
? 
Cauliflower 
+ 
+ + 
+. 
? ' 
Coconut 
+ 
+ + 
? 
? 
Coconut oil 
- 
- 
- 
? 
Corn, white 
- 
+ + 
- 
? 
Corn, yellow 
+ 
+ + 
- 
? 
Cottonseed oil 
+ 
- 
- 
? 
Eggplant (dried) 
? 
+ + 
? 
? 
Grape juice 
p 
+ 
+ 
? APPENDIX 
481 
B. VITAMINS IN DIFFERENT FOODS (Continued) 
Name of Food 
Vitamin 
A 
Vitamin 
B 
Vitamin 
C 
Vitamin 
D 
Grapefruit 
? 
+ + 
+ + 
? 
Lemon juice 
? 
+ + 
+ + + 
? 
Lettuce 
+ + 
+ + 
+ + + 
? 
Orange juice 
+ 
+ + . 
+ + + 
? 
Prunes 
? 
+ 
- 
? 
Oats 
+ 
+ + 
- 
? 
Rice, polished 
- 
- 
- 
? 
Rutabaga 
p 
+ + 
+ + + 
? 
Potato, sweet 
+ + 
+ 
? 
? 
white (boiled 15 min.) . . 
? 
+ + 
+ + 
? 
white (baked) 
? 
+ + 
+ 
? 
Peas 
+ + 
+ + 
+ 
? 
Parsnips 
? 
+ + 
? 
? 
Peanuts 
+ 
+ + 
? 
? 
Squash, Hubbard 
+ + 
? 
? 
? 
Sugar 
- 
- 
- 
? 
Tomatoes (raw or canned) . . 
+ + 
+ + + 
+ + + 
+ + 
Spinach (fresh) 
+ + + 
+ + + 
p 
? 
Turnips 
? 
+ + 
? 
? 
Wheat (whole) 
+ 
+ + 
- 
? 
Bread, white (milk) .... 
+ 
+ 
? 
? 
whole wheat (milk) . . . 
+ + 
+ 
? 
? 
+ indicates that food contains the vitamin. 
+ + indicates that food is a good source of the vitamin. 
4H—(- indicates that food is an excellent source of the vitamin. 
— indicates that the food contains no appreciable amount of the 
vitamin. 
? indicates that it is not known whether vitamin is present. 482 
APPENDIX 
Name of Food 
Refuse 
Edible 
Portion 
Money Value 
of Food as 
PURCHASED 
COMPARED 
WITH AN 
Equal 
Weight of 
White Bread 
Water 
Protein 
Carbo- 
hydrate 
Calcium 
(CaO) 
Potassium 
(K20) 
3^ 
JO 
froT 
O w 
X 
PM 
d 
0 
Apples 
0/ 
/o 
25 
0/ 
/o 
84.6 
0/ 
/o 
0.4 
0/ 
/o 
0.5 
0/ 
/O 
14.2 
0/ 
/o 
.014 
0/ 
/o 
•15 
0/ 
/O . 
•°3 
0/ 
/o 
.0003 
.07 
Bacon 
— 
18.8 
9.9 
67.4 
— 
I.95 
Beans (string) .... 
7 
89.2 
2-3 
o-3 
7-4 
.075 
.28 
.12 
.0016 
.20 
Beans (lima, dried) . . . 
— 
10.4 
I8.I 
i-5 
65.9 
.10 
2.10 
77 
.0070 
I.78 
Beef (round, lean) . . . 
8.1 
70 
2I.3 
7-9 
— 
.Oil 
.42 
.50 
.0038 
I.72 
Beets (fresh) 
20 
87.5 
1.6 
0.1 
9-7 
•03 
•45 
.09 
.0006 
.22 
Bread (white) .... 
— 
35-6 
9-3 
1.2 
527 
•03 
.10 
.20 
.0009 
1.00 
Bread (whole wheat) . . 
— 
38-4 
9-7 
0.9 
497 
.04 
.27 
.40 
.0015 
1.02 
Butter • 
— 
1 r 
1 
85 
— 
.02 
.02 
•03 
— 
I.48 
Buttermilk 
— 
9i 
3 
0.5 
4.8 
•15 
.18 
.22 
— 
•27 
Celery 
20 
94-5 
1.1 
0.1 
3-3 
.10 
•37 
.10 
.0005 
.08 
Cheese (cream) .... 
— 
34-2 
25 9 
33-7 
2.4 
2.69 
Chestnuts (fresh) . . . 
16 
37-8 
5.2 
4-5 
35-4 
.04 
.50 
.20 
.0010 
.64 
Chocolate 
— 
5-9 
12.9 
48.7 
3°-3 
.14 
.90 
I.98 
Clams (without shell) . 
— 
80.8 
10.6 
1.1 
5-2 
.40 
.91 
Corn (green) 
61 
75-4 
3-1 
1.1 
19.0 
•008 
•131 
.22 
.0008 
•13 
Cornmeal (granular) . . 
— 
12.5 
9.2 
1.9 
75-4 
.015 
•17 
•30 
.0011 
I.IO 
Dates (dried) 
10 
15.4 
2.1 
2.8 
78.4 
.10 
.12 
.0030 
■54 
Eggs (uncooked) . . . 
| 11.2 
73-7 
13-4 
10.5 
— 
•093 
.165 
•37 
.0030 
1.23 
C. FOOD VALUES AND COSTS APPENDIX 
483 
Figs (dried) 
— 
18.8 
4-3 
°3 
74.2 
.299 
I.478 
•332 
.0032 
1.02 
Fish (cod, dressed) . . . 
29.9 
82.6 
16.5 
0.4 
— 
.015 
.40 
.40 
.0004 
.91 
Fowl (chicken, plucked) . 
25.9 
637 
19-3 
16.3 
—- 
.015 
•56 
•58 
1-33 
Grapes 
25 
77-4 
i-3 
1.6 
19.2 
.024 
.25 
.12 
.0013 
.16 
Ham (smoked, medium fat) 
136 
40-3 
16.3 
38.8 
— 
1.71 
Honey 
— 
18.2 
0.4 
— 
81.2 
1/1 
0 
q 
.50 
.04 
.0010 
•36 
Lamb chops 
13-5 
47.6 
21.7 
29.9 
— 
1.95 
Lettuce 
15 
94 7 
1.2 
•3 
2.9 
.05 
.42 
.09 
.0010 
.10 
Milk 
87 
3-3 
4 
5.0 
.168 
.171 
.215 
.0002 
•35 
Mushrooms 
— 
88.1 
3-5 
0.4 
6.8 
.024 
.46 
.24 
•32 
Muskmelon 
50 
89.5 
0.6 
— 
9-3 
.024 
.283 
•035 
.0003 
.04 
Oatmeal 
— 
7-3 
16.1 
7.2 
67.5 
•13 
.458 
.872 
.0036 
1.72 
Onions (fresh) .... 
10 
87.6 
1.6 
o-3 
9.9 
.06 
•23 
.12 
.0005 
•15 
Oranges 
27 
86.9 
0.8 
0.2 
11.6 
.06 
.22 
.05 
.0003 
• OI 
Peanuts 
24.5 
92 
25.8 
38.6 
24.4 
.10 
.85 
.90 
.0020 
2.16 
Peas (dried) 
— 
9-5 
24.6 
1.0 
62.0 
.14 
I.06 
.91 
.0056 
2.30 
Pork (loin chops, lean). . 
23-5 
60.3 
20.3 
19 
— 
.012 
•34 
•45 
1.51 
Potatoes (white) .... 
20 
78.3 
2.2 
0.1 
18.4 
.Ol6 
•S3 
.14 
.0013 
.21 
Potatoes (sweet) .... 
20 
69 
1.8 
0.7 
27.4 
.025 
•47 
.09 
.0005 
.27 
Prunes (dried) .... 
IS 
22.3 
2.X 
— 
73-3 
.06 
1.20 
■25 
.0029 
.40 
Raisins 
10 
14.6 
2.6 
3-3 
76.1 
.08 
1.00 
.29 
.0050 
•52 
Rice 
— 
12.3 
8.0 
o-3 
79.0 
.012 
.084 
.203 
.0009 
.98 
Spinach 
— 
92-3 
2.1 
o-3 
3-2 
.09 
•94 
•13 
0032 
.19 
Squash 
5° 
88.3 
1.4 
0.5 
9.0 
.02 
.05 
.08 
.0008 
.08 
Tomatoes 
— 
94-3 
0.9 
0.4 
3-9 
.20 
•35 
.059 
.0004 
.09 
Walnuts (soft shelled) . . 
58.1 
2-5 
l6.6 
634 
16.1 
.108 
•44 
•77 
.0021 
1.03 484 
APPENDIX 
Note. The values appearing in the last column of the table ou 
the preceding pages have been secured by the use of the formula 
given in Murray’s Economy of Nutrition (Appleton). This author 
finds that on an average a pound of protein costs about 20 times as 
much as a pound of carbohydrate, and a pound of fat about four 
times as much. The value of a food may therefore be said to be 
equal to the protein x 20 + fat x 4 + carbohydrates. The method 
of making the computations will be understood from the following 
sample problem, in which the relative values of pecans and of an 
equal weight of dried figs are calculated. Pecans (as purchased) 
contain 5.1 per cent protein, 37.9 per cent fat, and 8.2 per cent car- 
bohydrates. Dried figs contain 4.3 per cent protein, .3 per cent fat. 
and 74.2 per cent carbohydrates. The relative values of these two 
foods may therefore be expressed by the equation 
5.1 x 20 4- 37-9 x 4 + 8.2 _ 261.8 _ j g2 
4.3 x 20 + .3 x 4 + 74.2 161.4 
That is, a pound of pecans ought, theoretically, to sell in the market 
for 1.62 times as much as a pound of figs. In the table on page 482 
the value of bread is taken as 1, and the other foods are compared 
with it. The values of any two foods can be compared in this way, 
and it can then be determined which is the cheaper at current 
market prices. The teacher will understand, however, that in de- 
termining the real value of an article of food there may be many 
factors not taken into account in the above formula. 
Bulletin No. 28 of the United States Department of Agriculture 
contains a very complete list of analyses showing the chemical com- 
position of American foodstuffs. It is sold by the Superintendent 
of Public Documents, Washington, D.C., for ten cents. PRONOUNCING GLOSSARY 
This glossary is intended chiefly to help the pupil in the pronunciation 
of the more difficult terms. A few words are defined; the meaning of 
those not defined is made clear in the places where they occur in the text. 
abdomen (ab-do'men). 
abdominal (ab-dSm'i-nal). 
adenoid (ild'en-oid). 
Agave (a-gah've). 
ameba (a-me'ba), a rather large 
protozoan that has no cell wall 
about it, changes its shape, and 
takes in its food in the same way 
as a white blood corpuscle engulfs 
bacteria (Fig. 9). 
amylopsin (a-mi-ldp'sin). 
anemia (a-ne'mi-a). 
Anopheles (A-nSf'6-lez). 
appendicitis (ap-pen-dl-si'tis). 
aqueous (a'que-us). 
astigmatism (as-tlg'mat-ism). 
auricle (o'ri-cl). 
bacillus (ba-sll'liis). 
bacterium (bak-te'ri-um). 
beriberi (b&r'i-ber'i). 
bronchial (brong'ki-al). 
bronchitis (brong-ki'tis). 
canine (ka-nin'). 
capillary (cap'il-la-re). 
cerebellum (ser-e-bel'lum). 
cerebro-spinal (ser'e-bro-spl'nal). 
cerebrum (ser'e-brum). 
chloral (klo'ral). 
choroid (ko'roid). 
cocain (ko'ka-in). 
coccus (kdk'kus). 
coccyx (kdk'six). 
cochlea (kSk'le-a). 
communicable (com-mu'ni-ca-ble) 
disease, a disease that one person 
can contract from another. 
cornea (cor'ne-a). 
corpuscle (kor'pusl). 
Culex (ku'lex). 
dengue (dSn'ga). 
dentine (dSn'tm). 
diaphragm (di'a-fr&m). 
diphtheria (dlf-the'ri-a). 
disinfectant (dis-in-fgct'ant). 
dysentery (dls'en-ter-y), an intes- 
tinal disease in which there is a 
bloody discharge from the bowels. 
emetin (em'e-tin). 
enzyme (en'zim). 
epidemic (Sp-i-dSm'ik) disease, a 
disease that people catch from one 
another easily and which many 
people have at once. An outbreak 
of a communicable disease. 
esophagus (e-sof'a-gus). 
Eustachian (yu-stak'ke-an). 
femur (fe'mur). 
fertilization (fer-til-!z-a'shun). 
gangrene (g&ng'gren), inflamma- 
tion that goes on until part of the 
tissue is dead. 
germ (jerm), a bacterium or a pro- 
tozoan that can cause disease. 
germicidal (jer-mi-sl'dal), germ- 
killing. 
glycogen (gli'ko-jen). 
hasheesh (hash-esb/) • 
hemoglobin (hSm-o-glo'bin). 
humerus (hyu'me-rus). 
humidifier (hyu-mid'i-fi-er). 
hygiene (hi'ji-en or hl'jen). 
hygienic (hl-je-en'ik). 
485 486 
PRONOUNCING GLOSSARY 
incisor (in-sl'sor). 
infected (in-fekt'ed), containing 
germs, as an infected wound. 
infectious (in-fek'shus) disease, a 
disease, the germs of which can be 
passed from one person to another. 
larynx (lar'mks). 
lipase (lip'as), 
lymphatic (lim-fat'ik). 
lysol (ll'sol). 
magnesium (mag-ne'zhe-um). 
medulla oblongata (med-fil'la 5b- 
lon-gah'ta). 
meningitis (m&i-m-jl'tis). 
miasma (ml-az'ma). 
microbe (ml'krob), a living thing 
so small that it can be seen only 
through a microscope. 
molar (mo'lar). 
narcotic (nar-k6t'ic). 
nicotin (nlk'o-tln). 
nocardia (no-card'e-a). 
opsonin (6p'so-nIn). 
pancreas (p&n'kre-as). 
papilla (pap-il'ah). 
patella (pa-t51'la). 
pellagra (pel-ig'ra or pg-lah'gra). 
pepsin (pSp'sin). 
permanganate (per-man'gan-at). 
phalanges (fa-ian'jez). 
pharynx (f&r'inks). 
phosphorescent (f5s-fo-res'ent). 
poliomyelitis (pSl-1-5-mI-g-ll'tis). 
pollen (pSl'len). 
polyp (p61'ip). 
proboscis (pro-b6s'is). 
protein (pro'te-in). 
protoplasm (pro'to-plasm). 
protozoon (pro-to-zo'Sn). 
ptomaine (to'ma-In). 
ptyalin (ti'a-lin). 
pupa (pu'pa). 
pus (pus). 
pyorrhea (pi-6-re'a). 
rabies (ra'bi-ez). 
respiratory (res'pi-ra-to-re). 
retina (r5t'i-na). 
saliva (sal-l'vah). 
salivary (s&l'i-va-re). 
sanatorium (s5.n-a-to'ri-um), a place 
•where people go to regain health; 
a hospital for the treatment of 
patients who can be cured. 
sciatic (si-at'ik). 
sclerotic (skle-r5t'ik). 
sepal (sSp'l). 
serum (se'rum). 
spirillum (spl-rfl'lum). 
sputxun (spu'tum), matter coughed 
up from the lungs and air passages. 
stamen (sta'men). 
stegomyia (stgg-5-ml'ya). 
stomoxys (sto-mOk'sis). 
strychnin (strfk'nin). 
tetanus (tSt'a-ntls). 
tonsillitis (tSn-sfl-ll'tis), inflamma- 
tion of the tonsils. 
trachea (tra'ke-a). 
trachoma (tra-ko'ma). 
trypsin (trip'sin), 
tuberculosis (tu-ber-ku-lo'sis). 
tuberculous (tu-ber'ku-lus), in- 
fected with the germs of tuberculosis. 
tympanic (tim-pan'ik). 
tympanum (tim'pan-um). 
uretur (ioi-re'ter). 
virulent (vlr'u-lent), powerful in 
producing disease. 
virus (vi'rus). 
vitreous (vlt're-us). INDEX 
A star (*) after a page number indicates that an illustration of the subject 
appears on that page. 
Accidents, 433-444; as cause of death, 
445*. 
Accommodation of eye, 326, 327. 
Adenoids, 285-289*. 
After-effects of infectious diseases, 204. 
Air, relation to respiration, 266, 267; 
impurities of, 269; importance of 
fresh, 272-274*, 278-280*; compo- 
sition of, 273; too dry, 275* 290; 
too moist, 276; necessity for motion 
in, 276-278; relation to nervous sys- 
tem, 317. 
Air passages, 33-35*, 43, 47, 72; dis- 
eases of, 36-74*. 
Air sacs, 35*. 
Alcohol, 14, 15, 42, 44, 58, 422-431; 
effect on heart, 262; effect on body 
heat, 301; as a food, 374-376; 
source of, 423; effect on health and 
length of life, 424, 426; effect on 
cells, 426; effect on mind, 428-429; 
permanent effects, 428, 448; effect 
on muscles, 429-430; effect on 
strength, 430. 
Alimentary canal, 75*, 358; diseases 
of, 75-94*- 
Amino-acids, 379. 
Anemia, 138. 
Animals, as carriers of disease germs, 
9, 37, 43, 50, 59, 76, 78, 82, 98, 101, 
128-131, 196, 205; bacterial dis- 
eases of, 59, 99, 134, 198, 199, 205, 
206. See also Insects. 
Anopheles, m-112*. 
Antidotes for common poisons, 443. 
Antitoxin, 11, 12; for tetanus, 31; 
for diphtheria, 39-41; for menin- 
gitis, 96. 
Apoplexy, cause of, 262. 
Appendicitis, 24, 25. 
Appendix, vermiform, 358*, 362. 
Arms, bones of, 229*, 231, 232, 233*. 
Arteries, 252, 253*, 255, 259*, 426, 
435, 453- 
Ascaris lumbricoides, 135. 
Astigmatism, 327, 330. 
Auricles, 253*, 254, 255*. 
Bacillus, 18*; pyocyaneus, 25*; of 
tetanus, 29*; of diphtheria, 36*, 
51, 84; Pneumococcus, 43*; of 
influenza, 47 *; Pneumobacillus, 
50*; Micrococcus catarrhalis, 51; of 
tuberculosis, 53, 54*, 59, 61; of 
typhoid, 78; colon, 81; of dys- 
entery, 81; of diarrhea, 83; menin- 
gococcus, 95, 96*; of leprosy, 97 
Koch-Weeks, 97*. 
Bacteria, 6, 8, 18-20*, 22*, 24-28*, 
32, 71, 72, 89, 91, 151-157, 363, 366, 
396, 398, 448. See also Disease 
germs. 
Bandages, how applied, 235*, 434* 
435*. 
Bathing, 290, 292, 299-300. 
Bedbugs, 9. 
Bichlorid of mercury, 131, 159. 
Bicuspids, 401, 403*, 404*. 
Bile, 362, 363*, 364.] 
Biniodid of mercury, 159. 
Black-leg, 99. 
Black-tongue, 206. 
Bleeding, treatment of, 435*. 
Blind staggers in horses, 76. 
Blood, corpuscles of, 11-13*, 17; 
“impure,” 27, 126; “pure,” 126; 
circulation of, 251-260*; function 
of, 252. See also Corpuscles, Lymph, 
and Plasma. 
Blood poisoning, 25, 26. 
Blood vessels, 252-255*, 257*, 260*; 
effect of alcohol on, 262. 
Body, growth from single cell, 223*; 
keeping in repair, 226; frame- 
work of, 228-236; carriage of, 243- 
249*; danger of chilling, 298; 
of overheating, 298. 
Body heat, how regulated, 296*, 297; 
relation to alcohol, 301. 
Boils, 22, 24, 25, 27. 
Bones, number of, in body, 228; 
names of, 229*; carpal and tarsal, 
229*, 232; in skull, 230; in chest, 
231; in shoulder, 231; in pelvis, 231; 
in limbs, 231; in hands, 232 ; com- 
position of, 232; in foot, 232, 246; 
treatment of broken, 235; in ear, 
336. See also Skeleton. 
Books, germs on, 166. 
Boracic acid, use of, in treatment of 
eyes, 323. 
Bovine tuberculosis, 59. 
Bowels, importance of keeping open, 
290, 391--392. 
487 488 
INDEX 
Brain, 304; structure and functions 
of, 305. 306*, 307*. 
Bronchial tubes, 33, 34*, 35*, 266, 
267*, 268*. 
Bronchitis, 33, 51, 72, 293. 
Bubonic plague. See Plague. 
Buildings, disinfection of, 162, 201. 
Bums, treatment of, 436. 
Calcium, need of, in body, 352-353. 
Calories, 383, 384. 
Cancer, 199; of throat, 270, 417. 
Capillaries, 252, 257, 265, 267. 
Carbohydrates, 350, 371, 373, 387. 
Carbolic acid, 56, 131, 160. 
Carbon dioxid, 225, 266, 267, 274, 
37i, 423- 
Carbuncles, 22, 24, 25. 
Carriers. See Germ carriers. 
Cartilage, 233. 
Catarrh, 33, 51, 71, 293. 
Cattle, and germ diseases. See Ani- 
mals. 
Cell division, 222*, 223. 
Cells, 3-5*, 6; of human body, 219- 
225*; of plants, 219, 222*; number 
of, 224, 251; effect of alcohol on 
human, 426. 
Cerebellum, 306*, 307*. 
Cerebrum, 306*, 307*. 
Chest, bones of, 229*, 230*, 231; 
organs of, 266*. 
Chicken pox, 117, 133. 
Chlorid of lime, 160, 161. 
Cholera, 75, 98; of fowls, 99. 
Cholera infantum, 84, 154. 
Circulation of blood, 251-255*. 
Cities, sanitary problems of, 187. 
Citizens, duties of, 124, 167, 173, 
187-191*. 
Cleanliness, and food, 153. 
Climate, and consumption, 65. 
Closets, 138, 140, 169, 203. 
Clothing, object of, 295-296*; suiting, 
to weather, 299; on fire, 436. 
Coccus, 18*, 19. 
Cold, and food, 153. 
Colds, 13, 33, 50-52*; cause of, 288; 
remedies for, 289-291, 293; effect 
of drafts on, 291; chronic, 293. 
Colon bacillus, 81, 84. 
Communities, responsibility of, for 
health, 115, 143, 149, 171-176, 
187-193- 
Connective tissue, 223*. 
Constipation, dangers of, 391-392; 
remedies for, 392. _ 
Consumption, 33, 54, 57, 58*, 61-71*, 
161. See also Tuberculosis. 
Contact infection, 201. 
Cooking, to avoid food poisoning, 76. 
Corpuscles, 11*, 12* 13, 103*; of the 
blood, 256-257*; function of red, 
256; function of white, 256, 449; 
increasing white, 290; increasing 
red, 352. 
Corrosive sublimate, 159. 
Coughing, 48, 51, 55. 
Cowpox, 123. 
Croup, membranous, 36, 184. 
Crown-gall, 99. 
Crypts, 285*. 
Culex, 112*. 
Dairy, a model, 155*. 
Death rates, 78*, 182, 184; decrease 
in, through sanitation, 39*, 40*, 
66*, 67*, 68*, 79*, 125*, 129*, 178*, 
191*, 192*, 193*. 
Dengue, no. 
Dermis, 21*, 296*. 
Dew sores, 137. 
Diaphragm, 266*. 
Diarrhea, 75, 83-85*, 166, 184. 
Diet, in relation to pellagra, 209-210; 
low protein, 379-382*; objections 
to heavy meat, 382-383 ; in relation 
to energy, 383-386; general prin- 
ciples of, 386-387, 390-391; im- 
portance of milk in, 387. 
Digestion, 357-369; organs of, 358- 
363*, 366; juices of, 360-362; 
process of, 363-366. 
Diphtheria, 33, 36-41*, 184. 
Disease, prevention of, 215 ; prevalence 
through ignorance, 216*, 217; re- 
sistance of body to, 449. 
Disease germs, effect on heart, 259; 
of colds, 288, 289; of catarrh and 
bronchitis, 293; effect of, on the 
eyes, 323, 330; effect of, on the ear, 
338; in the teeth, 400; defined, 
447-448; how body resists, 449; 
relation of good health to, 449-451. 
See also Germs. 
Diseases, germ, causes of, 8, 447- 
448; how avoided, 9, 16; how 
fought by blood, 11-13; keeping up 
resistance to, 14-16; effect of alco- 
hol on, 15; caused by alcohol, 427; 
as a cause of death, 445; classes 
of, 447; physiological, 451; infec- 
tious, 452. 
Dishes, disinfection of, 34, 56, 57, 159- INDEX 
489 
Disinfection, 27, 30, 52, 56-57, 85, 
118, 130, 152, 158-163*, 201. 
Dislocations, 234. 
Distemper, gg. 
Dogs, and rabies, 128, 129*. 
Drafts, dangers of, 291-292. 
Drinking cups, public, 37, 51, 164*, 
165. 
Drowning, treatment of apparent, 
437-438*. 
Drugs, effect on the mind, 411, 412. 
Drying as a disinfectant, 158. 
Dust, 26, 71-74*, 179*; effect on 
respiration, 268-269*. 
Dusting, 73*. 
Dysentery, 75 ; acute, 81; chronic, 81, 
131*- 
Ear, 334-339*; inflammation of the 
middle, 25, 43; function of, 335 ; 
structure of, 335-337*; bones of, 
336*; inner, 336-337*; running, 
338; care of, 338-339. 
Earache, 338. 
Education in regard to germ diseases, 
need for, 186, 187. 
Eelworms, 135. 
Electricity, dangers from, 438-439. 
Elements in the body, 349. 
Elephantiasis, no. 
Enamel of teeth, 396*. 
Energy, how body secures, 383 ; effects 
of diet on, 384; proper foods for 
supplying, 385. 
Enzymes, 359-365- 
Epidemic cerebro-spinal meningitis. 
See Meningitis. 
Epidermis, 21*, 296*. 
Erysipelas, 22, 24, 26. 
Esophagus, 75*, 358*, 360, 364. 
Eustachian tube, 284*, 335*, 338. 
Exercise, effects on heart, 260; proper 
regulation of, 261; as aid to diges- 
tion, 391*, 392. 
Eye, 321-332; natural protection of, 
322; muscles of, 323; structure, 
323-325*; accommodation of, 326, 
327; care of, 328*, 331*, 332; tests 
for, 32g*, 333; effect of disease 
germs on, 330; foreign bodies in, 
439- 
Eye strain, 328*. 
Eyes, and germ diseases, 96, 97*, 165*. 
Fainting, treatment for, 438. 
Farmhouses, and sanitation, 190. 
Far-sightedness, 327. 
Fats, as food, 350, 362, 363*, 371, 373*, 
374, 388. 
Fermentation, 423. 
Filaria, 1x0. 
Filterable viruses. See Virus. 
Filters, 86, 92, 174. 
Fish, as mosquito killers, 114. 
Fleas, as disease carriers, 9, 98. 
Flies, 9, 22*, 37, ss, 78, 83, 97, ns, 
145-150*, 185, 203. 
Flowers, parts of, 220, 221*; fer- 
tilization of egg in, 222. 
Flytraps, 148, 149. 
Follicles, 297. 
Food, and consumption, 63; infec- 
tions through, 151, 152*, 153. See 
also Milk. 
Food poisoning, 75, 76, 82. 
Foods, 347_3S6; function of, 348- 
349; classes of, 330; selection of, 
355; absorption of, 355-366*; 
storage of, in body, 373; surplus in 
body, 374; and health, 378-393; 
cost of, 392-393- 
Foot, 246-248; bones of, 229*, 232, 
246; structure of, 246; function of, 
247-248; proper position of, in 
standing and walking, 249. 
Foot-and-mouth disease, 198. 
Formaldehyde, 162. 
Fowl cholera, 99. 
Fowl tumor, 199. 
Fresh air, 14*, 35, 45*, 63*, 64*, 65*, 
85, 190. 
Frostbite, treatment for, 440. 
Fungi, diseases caused by, 100. 
Ganglia, 304. 
Garbage, and flies, 147. 
Gas bacillus, 32. 
Gastric juice, 361, 364. 
German measles, 132. 
Germ carriers, 38, 39, 43, 79, 91, 96. 
Germicidal substance in the blood, 13, 
123/126-127, 449. 
Germs, 1, 2, 4, 5 ; definition of, 6, 210; 
source of, 7, 8; relative abundance 
of, 8; how enter the body, 8; how 
to avoid, 9, 10; sickness, how caused 
by, 11; how destroyed by body, 
11-13*. See also Bacillus, Bacteria, 
Disease germs, and Protozoa. 
Glanders, 99. 
Glands, lymphatic, 54, 61; sweat, 
296*, 297 ; of the eyelids, 322*; sal- 
ivary, 358, 359, 360*; digestive, 
359*; gastric, 361. 490 
INDEX 
Glycogen, 373. 
Government, advantages of, 171-176; 
duties of, in relation to sanitation, 
177-186, 187. 
Granulated lids, 330. See also Tra- 
choma. 
Grip. See Influenza. 
Ground itch, 137. 
Habits, 311; unhygienic, 164-170*. 
Hair, structuie of, 296*. 
Hair follicles, 21*, 22, 100. 
Hands, disinfection of, 51, 52, 160- 
161*. 
Headache remedies, dangers of, 261. 
Health, knowledge of germs a safe- 
guard to, 2; and cells, 4; how pro- 
tected from germ diseases, 9, 10, 12*, 
13; keeping up, 14-16, 35, 44, 85; 
relation of nervous system to, 318- 
320; limiting factors of, 446; re- 
lation of, to disease germs, 449; 
possibilities of good, 453. 
Health officers, work of, 143, 172- 
174, 188, 189, 191*. 
Hearing, 321, 334-339*. 
Heart, 252-262*; and pneumonia 
toxin, 42; structure of, 253-255*; 
action of, 254, 255*; care of, 258; 
effect of disease germs on, 259; 
of exercise on, 260, 261; of tobacco 
on, 261; of headache remedies on, 
261; of digestive troubles on, 262; 
of alcohol on, 262, 453. 
Heat, as a disinfectant, 20, 57, 158. 
Hemoglobin, 352. 
Hookworms, 136-138*; weakness 
caused by, 139 ; in dogs, 206. 
Hospitals, 178, 202. 
Housefly, 145-150*. See also Flies. 
Houses, disinfection of, 58*, 67. 
Human wastes, safe disposal of, 203. 
Humidifier, 275*. 
Hydrophobia. See Rabies. 
Hygiene, importance of, in treatment of 
tuberculosis, 67. 
Immunity. See Resistance. 
Incisors, 401, 402*, 403*, 404*. 
Incubation period, of tetanus, 29; of 
diphtheria, 36; of whooping cough, 
49; of typhoid fever, 77; of mumps, 
98; of malaria, 105; of smallpox, 
117; of rabies, 128; of measles, 132; 
of chickenpox, 133; of scarlet fever, 
I33-_ 
Infantile paralysis, 195. 
Infection, contact, 201. 
Inflammation, caused by pus-forming 
bacteria, 22. 
Influenza, 33, 34, 47-48*, 184. 
Inheritance, and consumption, 67. 
Insects as disease carriers, 9, 22*, 78, 
83, 97, 104-109*, no, 128, 134, 
145, 146*, 196. 
Inspection, medical, of schools, 202*. 
Intestinal diseases, 75-94*, 98, 131, 
151, 167-168. 
Intestinal worms, 135-140. 
Intestine, 75*; and growth of germs, 
75; and bacterial diseases, 75-94. 
Intestines, 358*, 361, 362, 363*, 365, 
366*. 
Iodine, 27. 
Iron in food, 352, 353, 354. 
Isolation, importance of, in germ dis- 
eases, 85, 162*, 163, 198, 201. 
Itch, 100, 137. 
Ivy poisoning, 441 *. 
Jaundice, infectious, 207-208. 
Jefferson, Thomas, 121*. 
Jenner, Edward, 1x9*. 
Joints, 233*. 
Kala-azar, 128. 
Kerosene, and mosquitoes, 114*; 
and flies, 149. 
Kidneys, 225, 372*, 453. 
Larynx, 33, 34*, 36. 
Legs, bones of, 229*, 231, 232. 
Leprosy, 97. 
Lethargic encephalitis, 196. 
Life, average length of, 213, 214*, 
453-454; laws of, 217; effect of 
alcohol on length of, 424. 
Ligaments, 233*. 
Light, as a disinfectant, 57, 158; for 
reading, 33°-33i*- 
Lime, in bones, 232; in food, 352. 
Limiting factor in health, 446. 
Liver, 75*, 358*, 362. 
Lockjaw. See Tetanus. 
Louse, and typhus fever, ig6. 
Lungs, 33, 34*, 35*, 225, 262-268*. 
Lymph, cells bathed by, 224, 257*; 
necessary for health of cells, 224-225; 
function of, 257-258. 
Lymphatic vessels, 258*. 
Lysol, 56, 160. 
Madstones, 130. 
Malarial fever, 103-108*, 112*, 184. INDEX 
Malta fever, 99. 
Manufacturing, dust in processes of, 74. 
Manure, and flies, 147, 148. 
Masks, gauze, 47*, 48. 
Mastoid cavity, 335*, 336. 
Mastoiditis, 336. 
Measles, 13, 132, 162*, 184, 207. 
Meat poisoning, 75, 76, 82. 
Mediterranean fever, 99. 
Medulla, 306*, 308. 
Meningitis, 24, 25, 54, 77, 95-96, 184. 
Meningococcus, 95, g6*. 
Micrococcus catarrhalis, 51. 
Milk, diseases contracted from, 36, 37, 
56, 59, 60, 79, 153-156*, 157; proper 
care of, 84, 85*; Pasteurizing, 156*; 
as a food, 352, 354; importance of, 
in diet, 387. See also Carbohy- 
drates. 
Milk of lime, 160, 161. 
Milk-sickness, 99. 
Mind, peaceful, necessary to health, 
318-320; effect of tobacco on, 415; 
effect of alcohol on, 428-429. 
Minerals, needed by body, 351-354, 
386; foods rich in, 353-3S4; in vege- 
table foods, 389. 
Molars, 401, 402*, 403*, 404*. 
Mosquitoes, 9, 63, 104-116*, 185, 190, 
203, 204. 
Mouth, infection by way of, 9, 33, 43, 
164. 
Mucous membrane, 283, 288, 292, 298, 
344*, 358, 359*. 
Mucus, 283, 289, 363, 366, 398; as a 
germ carrier, 165, 202. 
Mumps, 98. 
Muscles, function of, 238-242*; struc- 
ture of, 239. 
Muzzling, and rabies, 129. 
Nagana, 134. 
Narcotics, defined 412. See Drugs 
and Tobacco. 
Nasal chambers, 9, 33*, 35, 43, 51, 96. 
Near-sightedness, 327, 330. 
Necator, 136. 
Nerves, 304; cells of, 224*, 304-305*; 
fibers of, 304-305*; sciatic, 305; 
of sight, 321, 323*, 324*; of hearing, 
335*, 337! of touch, 342*, 343; 
of taste, 344; of smell, 344*. 
Nicotin, 411-412, 418. See also To- 
bacco. 
Nitric acid, and rabies, 130. 
Nocardia, 207. 
Nose, infection by way of, 9; struc- 
ture of, 282, 283* 284*; function 
of, 283; troubles of, 283, 284, 289; 
foreign bodies in, 440. 
Nursing bottle, 85*. 
Olfactory cells, 345. 
Open-air schobls, 274*, 278*, 279*, 
280*, 317. 
Opsonins, 449. 
Outdoor life, and consumption, 63. 
Outdoor sleeping, 272* 280. See also 
Fresh air. 
Oxygen, 225, 256, 265, 273, 276. 
Oxyuris, 136. 
Oysters, and typhoid fever, 78. 
Palate, soft, 284*. 
Pancreas, 358*, 362. 
Pancreatic juice, 362, 363*. 
Papillae of the skin, 342. 
Pasteur, Louis, 6, 142*; treatment, 
129. 
Pasteurization of milk, 60, 156*, 198. 
Pear blight, 99. 
Pellagra, 209, 366, 368. 
Pencils, infection by, 22*, 36, 37*, 51. 
Pepsin, 361, 363*, 364, 365. 
Peroxide of hydrogen, 27. 
Pharynx, 33*. 
Phosphorescence, caused by protozoa, 
101*. 
Phosphorus, 350, 352, 353. 
Physiological diseases, 445*, 451. 
Pimples, 22, 24, 25, 27. 
Pink eye, 97*, 197, 330. 
Pinworms, 136. 
Plague, bubonic, 98, 175, 205. 
Plants, bacterial diseases of, 99, 194. 
Plasma, 256, 257*. 
Playgrounds, 185. 
Pneumo-bacillus, 50*. 
Pneumococcus, 43*. 
Pneumonia, 13, 24, 25, 33, 42-46, 47, 
50, 71, 77, 141, i84; 
Pneumonia germ, varieties of, 208. 
Poisoning, treatment for, 441-442. 
Poliomyelitis. See Infantile paralysis. 
Pollution, of soil, 87, 138, 140, 168; 
of water, 86*, 87, 168. 
Posture, 31-34*; mistakes in, 244, 
245*; vertical line test for, 244*, 
245*- 
Prohibition, 430. See also Alcohol. 
Proteins, 350, 360, 363*, 371, 373, 
374, 378, 379*, 380, 381*, 382, 383, 
385, 386, 387, 390, 393- 
Protoplasm, 349. 
491 492 
INDEX 
Protozoa, 6, 8, 101-102*, 103*; dis- 
eases caused by, 103-109, 128-134; 
diseases of animals caused by, 134. 
Ptomaine poisoning. See Food poison- 
ing. 
Pus, 24. 
Pus-forming bacteria, 24*, 25*, 28*, 84, 
95, 125, 133. 
Pyrethrum, 115. 
Quarantine, 38, 48, 49, 96, 118, 132, 
133, i77, 178*. 
Quicklime, 162. 
Quinine, 107, 108; as a cause of deaf- 
ness, 338-339- 
Rabies, 128-131*. 
Rats, and plague, 98, 134, 175, 185, 205, 
206. 
Reed, Dr. Walter, 109*. 
Reflex actions, 308, 309*, 310-312. 
Resistance to germs, 11-17, 28, 35, 
44-46, 52, 67, 84, 120, 126, 170, 205. 
Respiration, 265-270; objects of, 
265-266; organs of, 266*, 267*, 
268*; effect of dust on, 268*, 269*; 
effect of tobacco on, 270. 
Respiratory diseases, 33-74. 
Rest, in treatment of consumption, 
62; relation to nervous system, 316. 
Rheumatism, acute, 97. 
Ribs, 229*, 230*, 231. 
Rickets, 366-367. 
Ringworm, 100. 
Rocky Mountain fever, 196. 
Rots, 99. 
Roup, 99. 
Saliva, 360, 363*, 364. 
Salivary glands, 358, 359, 360*. 
Sanatoria, 62*, 66, 69*, 178. 
Sanitation, importance of, 141; mean- 
ing of, 143; responsibility for, 143, 
149, 154; public, 171-176; prac- 
tical results of, 187-193*. 
Scarlet fever, 133, 178*, 184, 205. 
Schick test, the, 138. 
Screening, 107, 147*, 155, 192*, 203. 
Scrofula, 54. 
Scurvy, 366-367. 
Septic sore throat, 156. 
Serum, 28; for diphtheria, 40; for 
meningitis, 96. 
Sewage, disposal of, 180, 203. 
Shoes, proper and improper, in re- 
lation to health, 246-249*. 
Shoulder, bones of, 229*, 231. 
Sickness, possibilities of preventing, 
2is*, 216*, 453. 
Sinuses, nasal, 293, 452. 
Skeleton, function of, 228; parts of, 
229*, 230^233. 
Skin, and disease germs, 5, 9, 21, 22; 
structure of, 5*, 21*, 296*, 297; 
function of, 296, 297. 
Skull, 229*, 230*. 
Sleep, outdoor, 280, 317; importance 
of, 314*. 315- 
Sleeping porch, 63*. 
Sleeping sickness, 128, 196. 
Smallpox, 13, 17, 117-127*, 184. 
Smell, function of, 344; organ of, 
344*; care of organ, 345. See also 
Nose. 
Soil, pollution of, 87,136,138, 140, 168. 
Sore eyes. See Eyes. 
Special senses, 321. See also Eye, 
Ear, Hearing, Smell, Taste, Touch, 
Vision. 
Spectacles, 328-329*. 
Spinal column, 229*; structure of, 
230*; function of, 230*; muscles 
of, 241*, 242, 243*. 
Spinal cord, 303*, 304, 308. 
Spirillum, 18*, 19. 
Spitting, dangers from, 37, 71-72, 167. 
Spores, bacteria, 19, 20*, 29*. 
Sprains, treatment of, 234. 
Sputum, germs in, 37, 43, 47, 55, 78, 
146*; disinfection of, 55, 56*, 57*. 
Stables, and flies, 148. 
Staphylococcus, 24*. 
Statistics, vital, 180-184. 
Stegomyia, 115*. 
Stimulants, drugs as, 411-412. 
Stomach, 75*, 225, 262, 358*, 360-361, 
363*, 364- 
Streams, pollution of, 86*, 8", 93*. 
Streptococcus, 24*, 25, 28, 50, 51, 84, 
97- 
Suffocation, treatment for, 438. 
Sugar, grape, 365; as a food, 385, 
388. See also Carbohydrates. 
Sulfur, burning of, 115. 
Sunlight, as a disinfectant, igo. 
Surra, 134. 
Sweat glands, 21*, 22, 296*, 297. 
Sweeping, 73*; compounds for, 73; 
proper methods of, 269*. 
Swimming pools, pollution of, 93. 
Swine plague, 99. 
Tartar on teeth, 398. 
Taste, 321, 344. INDEX 
493 
Tears, function of, 322*. 
Teeth, 395-407*; unhygienic ways of 
cleaning, 167; function of, 358; 
effects of bad, on health, 395; struc- 
ture of, 395-396*; decay of, 396*, 
407; care of, 397-407*; permanent, 
401; temporary, 401-403; straight- 
ening, 405. 
Temperature, proper, in rooms, 275, 
276; of body, 295, 349. 
Tendons, 239, 240*. 
Tetanus, 29-32*, 125. 
Tetter, 100. 
Texas fever, 134. 
Thoracic duct, 258. 
Throat, 284-289*; foreign bodies in, 
440. 
Thrush, 100. 
Tick fever, 134. 
Ticks, 9, 196-197. 
Tobacco, 409-419; effect on heart, 
261; effect on respiratory organs, 
270 ;* a drug, 411; effect on growth, 
412-414; on muscles, 414; on ner- 
vous system, 414; on the mind, 416; 
of moderate use of, 417-4x8; why 
a boy should not use, 419. 
Toe-itch, 137. 
Tonsillitis, 24, 25, 33. 
Tonsils, 33; structure of, 284*, 285; 
diseases of, 285*, 286*; remedy for 
infected, 287. 
Touch, functions and organs of, 341*, 
342*, 343- 
Touch corpuscle, 296*, 342. 
Towns, sanitary problems of, 188-190. 
Toxins, 11, 12, 448; of tetanus, 31; 
of diphtheria, 39, 40; of pneumonia, 
42 ; of influenza, 47; of food poison- 
ing, 76; of malaria, 104; of hook- 
worm disease, 138; intestinal, 452. 
Trachea, 33, 34*, 266, 267*. 
Trachoma, 197, 330. 
Treatment for consumption, 61, 62- 
66*. 
Trichuris, 136. 
Tuberculosis, 53-70*, 71, 74, 141, 174, 
179, 183, 184, 200, 207. 
Tumors, 199. 
Turpentine, 27, 131. 
Tympanic membrane, 335*, 336*. 
Typhoid fever, 77-80*, 86-88*, 141, 
161, 169, 174, 175, 184, 192*, 205. 
Typhus fever, 196. 
Ulcers, in bones, 77. 
Urea, defined, 372. 
Ureter, 372*. 
Uric acid, as waste product, 372, 383. 
Vaccination, 16, 28, 49, 80, 118*, 
119-127*, 205. 
Valves, of heart, 253*, 254, 255*, 259; 
of arteries, 259*; of veins, 260*. 
Vegetables, value of, as food, 389-390. 
Veins, 252, 260*. 
Ventilation, 35, 272-280; while sleep- 
ing, 272*, 280; necessity for, 272- 
274,276; in schools, 277-280*. See 
also Fresh air. 
Ventricles, 253*, 254, 235*. 
Vermiform appendix, 358*, 362. 
Vertebrae, 230*. 
Villages, sanitary problems of, 188. 
Villi, 361. 
Virus, pure, in vaccination, 125; 
filterable, 194. 
Vision, defects of, 327, 328; testing, 
329*, 333. See also Eye. 
Vital statistics, 180-184. 
Vitamins, 355, 386. 
Walking typhoid, 77. 
Warts, cause of, 199. 
Wash basins, 97, 167. 
Water, and disease germs, 78*, 79, 
80, 86-94*, 166, 168, 174, 179; 
and mosquitoes, 113*, 114*. 
Waterhouse, Dr. Benjamin, 120*.. 
Wells, 87, 89-92*, 93. 
Whipworms, 136. 
Whooping cough, 13, 33, 4g, 184. 
Wilt diseases, 99. 
Window-tent, 65*. 
Windows, in school, 277, 331. 
Worms, intestinal, 135-140*. 
Wounds, 9, 26-27*, 29-30*, 32, 130; 
care of, 434-435*. 
Yellow fever, 109, 112, 115*. CONSERVATION of HEALTH 
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