General hygiene

Front matter

3NIDI03W JO ABV

NATIONAL LIBRARY

3NIDIQ3W JO ABV

Preface

The knowledge gained by scientific research in hygiene has been standardized and simplified, and the average person can now apply hygienic principles to daily living as accurately as he can apply the scientific principles of me¬ chanical engineering to automobiling and radio telephoning. An ordinary person can now operate and care for the ma¬ chinery of his body with intelligence and certainty.

This book supplements the author’s “Personal Hygiene, Revised” and is designed for pupils in the sixth, seventh, and eighth grades.. It supplies the kind of hygienic in¬ formation which physicians and health officers have found that the people need. It is also a guide to teachers in super¬ vising and advising the pupils in their health habits and actions, and in directing them to observe the sanitary ar¬ rangements and practices in the school, the home, and the community.

The scientific information contained in this book is of a grade commensurate with the mental age of the pupils for whom it is designed. While “Personal Hygiene, Re¬ vised” dwells upon the practice of health chores by the individual pupils, “General Hygiene, Revised” emphasizes civic responsibilities, and will prepare the pupils for their future duties along public health lines.

The pupils who will use this book have the mental capac¬ ity and attainments of the average voting citizen, and can readily understand the principles on which modern public

PREFACE health movements are founded. About twenty-five years, or a generation of time, have hitherto been required for a knowledge of current progress in medicine and hygiene to become the common possession of the people ; but proper hygienic instruction in the school would reduce the years to less than ten, or the time which a pupil usually spends in a public school. The citizen who is properly informed regarding the possibilities of attaining physical and mental health will do what he can to make that knowledge avail¬ able to all the people. This book supplies the practical information which the future citizen will wish to trans¬ form into intelligent action.

Every effort has been put forth to make the book attrac¬ tive as well as truthful. The text is written in simple Eng¬ lish which can be easily read and understood. The illus¬ trations are largely new, and are designed to visualize and vitalize the text. While nearly all the cuts are from designs or photographs made by the author, the one on page 1 1 is from a painting owned by the Arlington Chemical Com¬ pany, and reproduced by their permission.

The demonstrations and experiments have practical bearings on hygienic living, and can be performed with the facilities which are available, in every school. The obser¬ vations which are suggested for the pupils to make are of matters which are of public interest in every community. The whole plan and execution of the book is in accordance with the best pedagogical standards.

Contents

CHAPTER

I. The Study of Hygiene

II. Organs and Cells

Chapter I

Body and Mind. — The body is a living machine, and the mind is the engineer that controls it. The body is useless without the mind, and the mind can do nothing except by means of the body. The two must work together. When either one is out of order, the other also suffers.

One of the greatest of all the differences between a man and a tree is that a man has a mind, while a

IO tree has none. A tree grows in the way in which the soil, the weather, and other trees compel it to grow. But a man can use his mind to choose his home, his food, the air which he breathes, and the work which he does. He can avoid those things which will harm his body, and can do those things which will keep it strong and sound. If a person’s body is in good order, we say that he is healthy.

The Joy of Health and Strength. — The mind takes delight in directing the actions of a sound body. A healthy boy runs for the fun of running fast, ^ and climbs hills and trees for the pleasure of using his strength. He studies difficult lessons for the joy of thinking, and puts his whole mind to a puzzle for the delight of solving it. He has no pains or other un¬ comfortable feelings, and he performs all his actions so smoothly and easily that he almost forgets he has a body.

Most boys and girls do not always feel bright and active, but sometimes they have aches and pains in their bodies, and are too weak to work or play or think. When they feel like this, they are either over¬ tired or sick.

Is Sickness Necessary? — People used to think that sickness was necessary. They supposed that diseases were caused by bad weather and by mighty powers in the air or ground, just as they supposed storms and earthquakes were caused. They thought that sickness could no more be prevented than rainy days.

ii

Painting by W. Granville-Smith

Storm and Sickness

A doctor’s visit during a snowstorm. It was formerly supposed that bad weather was the principal cause of sickness.

Now we know that most forms of sickness come from causes which can readily be prevented, such as dirt, spoiled food, foul air, and wrong eating. A school child can understand how the common forms of sick¬ ness are caused, and how they may be prevented.

Progress in Health Matters. — In the United States there are always over a million persons who are sick. About two hundred thousand doctors are occupied in caring for them. The expenses of the sickness and the value of the time lost by the sick are at least a billion dollars a year. But no one can estimate the suffering and anxiety which are borne by the sick and their friends.

There is not so much sickness among civilized nations now as formerly. We know this from a study of the records of deaths, and from the history of epidemics.

i. The death rate of a country is the number of persons dying each year in every thousand inhabitants. The governments of all civilized lands have long been keeping records of all persons who die in those countries. Before the year 1800, about fifty or sixty persons in every thousand inhabitants died each year in England, Germany, and the United States. Now, in these countries, only about fourteen persons die in every thousand inhabitants. But in India the death rate is now as high as it was in England a century ago. This is because the people of India are as ignorant of health matters now as the people of England were a century ago.

The average age at which persons die in civilized lands is now nearly double the average age at which they died a century ago. The tombs and mummies of ancient Egypt show that the Egyptians died at an average age of about twenty-two years. In the city of Geneva, Switzerland, the average age of persons dy¬ ing in the year 1600 was twenty-one years; in 1700, thirty- two years ; in 1800, thirty-eight years. Now, the average age of those dying in the United States is over fifty years. But in India and Russia the average age at death is now about twenty-five years, or about the same as it was in ancient Egypt. The people of those countries which are the most advanced in civi¬ lization and knowledge live about twice as long as the people of the less civilized lands.

Man-Made Causes of Sickness

Garbage and sewage at the back door of a restaurant. It is now known that most human sickness comes from unsanitary conditions which are made by man himself.

2. A disease which spreads through a whole town or country is called an epidem'ic or a pestilence. The people of olden times were always in fear of war and pestilence. Thousands of men were killed each year by useless and cruel wars, but millions of men, women, and children were killed by diseases which are now seldom seen. In England in the fourteenth century, half of the population died from the plague in a single year. One hundred and two English colonists landed at Plymouth, Massachusetts, in December, 1620, and before the next spring fifty-two of them had died from what was probably typhus (tl'fus) fever. In 1879 one tenth of the inhabitants of the Philippine Islands died from cholera (kol'er-a). The plague, typhus fever, and cholera are now almost unknown among most civilized peoples, but these diseases still go on in India and other less advanced lands. Now and then a few cases reach the United States, but the diseases do not spread because great care is taken to check them.

• Cause of Epidemics. — The great epidemics of olden times were spread in very simple ways, and could easily have been prevented. The plague was spread by rats and fleas which swarmed over the thatched roofs and mud floors of the huts of the people. About the year 1900 the plague was brought to San Francisco by rats that came on ships from foreign lands ; but the disease was stopped by making the foundations and cellars of the buildings ratproof, so that the animals could not find hiding places.

Typhus fever is caused by body lice and spreads among people who are overcrowded. This accounts for the large death rate among the colonists of Ply¬ mouth, who were badly overcrowded both on their ship and in their houses, and who had no proper means of bathing and of removing lice, and no way of separat¬ ing the sick from the well. To-day, there is hardly a place in the United States where people have to live in the way the colonists lived, and therefore typhus fever is almost unknown in this country.

Cholera is spread principally among those who drink impure water. In 1832 an epidemic of cholera broke out in New York, and all the people who could get away from the city left it in terror. At that time the drink-

The Croton Aqueduct over the Harlem River

This aqueduct, completed in 1840, brought pure water to the city of New York, and ended the danger of cholera.

ing water was drawn from wells which were dug along the edges of the streets, and into which slops and gar¬ bage thrown upon the ground, could drain. There¬ fore people were made ill from drinking the im¬ pure water from these wells. In 1840 pure water was brought to the city through the Croton aqueduct, and since that time the people of New York have not been in real danger of cholera.

These examples are given to show the simple nature of the causes of most diseases, and how they are in our control. It is not nice to have rats in our houses ; it is not fashionable to be dirty ; and we are ashamed to have a bad odor about our clothes or houses. But the feelings which well-bred persons have about dirt and bad odors are not founded merely upon style and show.

i6

Failure to keep rats and other vermin out of our houses, and failure to keep clean, would mean sickness and death now, just as in olden times. You may prevent a great deal of sickness by doing the simple things which every polite and thoughtful person in a modern community is expected to do.

Diseases of the Present. — Lep'rosy, plague, typhus fever, and smallpox were formerly extremely common in all civilized lands. Now, they seldom occur. Yellow fever and malaria have been wiped out of Pan¬ ama simply by the extermination of the mosquitoes there. But a great deal still remains to be done. Only about one third of all deaths in the United States are due to old age, and over half are caused by diseases which may easily be prevented. Typhoid (ti'foid) fever is still a common disease, and colds are ex¬ tremely common. Tuberculosis is now so common that it is called the great white plague , and one tenth of all deaths among white races are due to it. We think it is a terrible thing that one tenth of the people of the Philippine Islands should have died from cholera in 1879, and yet one person in every ten who now live in the United States will die from tuberculosis, unless a great deal more is done in the near future than has been done in the past to prevent the disease.

Helping Each Other to Keep Well. — You cannot keep well by thinking of yourself alone. You must think of the health of others in order to protect your own health. If you carelessly allow some one to catch i7 tonsillitis (ton-si-ll'tis) from you, he may give the disease to a third person, who may give the disease back to you a month or two after you recover from your first sickness.

You will often be soiled with dust from streets over which diseased persons and animals have scattered the germs of sickness. You will often breathe air which the sick have breathed, and will often buy food which has been handled by unhealthy persons. What others do will affect your own health, and what you do will affect the health of other persons. You are only one among hundreds of the inhabitants of a town, but the healthfulness of your town will depend on what each separate inhabitant does. When you help others to keep well, you also help yourself to be healthy.

Teaching the Care of Health. — A little child learns a great deal about the care of his body from his parents. When he goes to school, he learns more about its care from his teachers, and from the books which he studies. Later in life he learns still more from the advice of doctors, from public lectures, and from articles in books, newspapers, and magazines.

Public schools are among the best of all means for teaching the preservation of health. Most states now have laws that every public school shall teach its pupils how to take care of their bodies, and how to prevent dis¬ eases. If all boys and girls will learn to do their part in the promotion of health, the next generation of men and women will be a vigorous, happy race. Colds and tuberculosis will be as rare as leprosy is now. Nearly all will live to a ripe old age, and sickness and pain will be almost unknown. No one will feel that life is a burden, but all will feel the joy that comes from health and strength (p. io).

Hygiene. — The study of keeping the body in good health is called hygiene (hi'ji-en). In it you will study such subjects as bathing, eating, drinking, clothing, breathing, exercise, and sleep.

Hygiene also includes the study of the methods and conditions by which diseases are prevented. It there¬ fore treats of such subjects as pure food, wholesome drinking water, fresh air, and the disposal of sewage.

Anatomy and Physiology. — Before you can under¬ stand the care of the body, you must know something about the structure of its machinery, and how it does its work. The study of the structure of the body is called anat'omy, and the study of its work and action is called physiol' ogy. You must study the anatomy and physiology of each part of the body in order to under¬ stand the care of it.

What are some of the signs of good health ?

What are some of the signs of poor health ?

What effect does sickness of the body have upon the mind?

About how many persons in the United States are sick at one time? About how much money does sickness cost the people of the United States each year?

Give some reasons for thinking that there is less sickness now than formerly.

What is the average death rate in the United States?

What is the average length of life in the United States?

What is an epidemic?

Name some epidemics which used to be common, but now seldom occur.

What are some of the reasons why deadly epidemics no longer occur ?

Name some deadly diseases which are now common.

How does a person protect his own health when he helps others to keep well?

What is hygiene ?

What is physiology ?

What is anatomy ?

What is the object of teaching hygiene in schools?

For the Teacher. — The object of the study of hygiene is to cause the pupils to desire to maintain the machinery of their bodies in an efficient working state. Call attention to the dangers to which early men were subjected : — as storms and cold weather ; wild animals and savage men ; famine and war. Describe the means by which these dangers have been lessened.

Epidemic diseases were the next great dangers which threatened the exist¬ ence of the human race. Many of these have been conquered, but others still remain, and apparently new diseases appear. Modern modes of life bring new dangers from speeding automobiles, whirling machinery, and the close associa¬ tion^ crowds.

While great progress has been made in the past, yet still greater will be made in the future, if every pupil is instructed in the working of his body ma¬ chinery and the means of keeping it in good order.

Chapter II

Life and Growth. — The food upon which the body lives has no life, but it becomes living blood, flesh, and bone in the body. After remaining alive for a few days or weeks, the living flesh becomes worn out and is changed back to dead and lifeless forms, and new flesh is formed to take its place.

The constant building up of worn-out parts of the * body is what is called life and growth. Lifeless things change and go. to pieces, and cannot build themselves up again. Living things are said to be alive because they build themselves up as fast as they wear out.

The actions of growth and repair are only slightly under the control of the mind, and so go on while a person is asleep even better than they do while he is awake. The same kinds of action go on in a tree, which has no mind at all.

Division of Labor in the Body. — Each action of the human body takes place in a particular part. One part of the body prepares food, another supplies air to all the rest of the body, other parts carry the food and air through the body, and others get rid of the worn-out food and flesh. A part of the body which has a par¬ ticular work to do is called an organ.

Spinal cord

Organs of Digestion. — The action of changing food to forms which living flesh can use is called digestion. There are five principal organs of digestion : i , the mouth ; 2, a bag, called

the stomach, which receives the food when it is swal¬ lowed ; 3, a long tube,

called the intestine (fa¬ tes' tin), in which the food is dissolved ; 4, a mass of flesh, called the pan'creas, in which a liquid is pre¬ pared for dissolving the food; and 5, a large mass of flesh, called the liver, in which food is made a part of the blood.

Organs of Respiration.

The body cannot work, or even live, unless a con¬ stant supply of oxygen (ok'si-jen) from the air reaches every part.

Breathing, and the changes produced by the oxygen in the body, are called respira¬ tion. The principal organs of respiration are the lungs.

Organs of Circulation. — Blood carries oxygen and di¬ gested food through all parts of the body, and its flow

]. Intestine

Diagram of the Position of the Principal Organs of the Body is called the circulation. There are two principal or¬ gans of circulation: i, a pump, called the heart , which keeps the blood in motion ; and 2, a vast number of tubes, which conduct the blood through the body.

Organs of Excretion. — Getting rid of worn-out substances is called excretion. There are three princi¬ pal organs of excretion : the kidneys, the skin, and the lungs. The liver and the intestine are also im¬ portant organs of excre¬ tion.

Organs of the Nervous System. — All the parts of the body are made to help one another, and to work together, by means of the nervous system. There are three principal organs of the nervous system : 1, the brain , situated in the top of the head ; 2, the spinal cord , situated in the backbone; and 3, long strings of flesh, called nerves, which extend from the brain and spinal cord to all parts of the body.

Organs for Voluntary Work. — There are two organs for doing voluntary work : 1, the brain, which does the work of thinking ; 2, a large number of bundles of lean meat, called muscles, which produce motions. Stiff

Diagram of a Complete Unit of Living Matter

a, a cell ; b, a blood tube which brings food and oxygen to the cell and car¬ ries away its waste matter ; c, a nerve which carries messages between the cell and other parts of the body.

rods and plates, called bones , support the soft flesh and assist the muscles to produce nearly all the voluntary movements of the body.

Cells. — An organ is not like a lump of clay which is the same throughout its whole mass, but it is made up of microscopic units of living matter, called cells, which carry on all the work of the body. The cells are like separate ani¬ mals which form a per¬ fectly trained army under the control of master cells in the brain and spinal cord. They are supplied with food and oxygen by the blood ; and they work for the benefit of the whole body as they are ordered by the nervous system. A complete unit of living matter in the human body con¬ sists of three parts: 1, a cell; 2, a blood tube from which the cell gets its food and oxygen ; and 3, a nerve which tells the cell when and how to act.

Cells in Lower Animals and Plants. — All animals and plants are composed of cells. In the lowest forms of living beings each animal and plant is composed of a single cell. A common one-celled animal is called the slipper animal' cule, or parame'cium (-shl-um). It is microscopic in size, and is found in stagnant water.

Parameciums

(Magnified ioo times.) Each paramecium is a complete animal consisting of a single cell.

Place a handful of hay or dry grass in a jar of water, and leave the jar in a warm room. After two or three weeks the water will usually contain great num¬ bers of tiny white specks, each of which is a paramecium. If you look at a drop of the water with a microscope, you can see the shape and structure of the animals as they move rapidly through the water.

Collect some of the green, silky threads which float on still ponds, or grow on sticks and stones in the water. These threads are green plants called alga (al'je). Exam¬ ine a few of the plants under a microscope. You will see that each plant is a thread which con- Threads OF Pond Alce sists of a single row of oblong cells joined end to end.

All higher plants and higher animals, such as wheat or a cat, consist of masses of cells.

Size and Shape of Cells. — The different kinds of cells in the human body vary in size and shape, but not one of them is large enough to be seen with the naked eye. If you scrape the skin with a knife, you will get a white powder which looks like flour. This powder consists of cells from the outer covering of the skin. If this powder is examined with a microscope, the separate

Each thread consists of ob¬ long cells joined end to end.

cells appear like flat scales. Cells scraped from the in¬ side of the cheek look nearly the same . These cells meas¬ ure from one five-hundredth to one one-thousandth of an inch across, and are extremely thin.

A muscle cell is shaped like a string, and is about one five-hundredth of an inch in diameter and about one fiftieth of an inch in length. A blood cell is round and almost flat, and measures about one three- thousandth of an inch across. If you put a bit of flesh under a microscope, you can tell from what organ it came by noticing the size, shape, and arrange¬ ment of its cells.

How Cells Grow. — Most of the cells of a baby’s body are of the same size and shape as the cells of a

Cells from the Inside of the Cheek

(Magnified ioo times.) These are cells of the kind called epithelial.

12 3

Diagram of Cell Division

After a cell reaches its full size, it may split into two parts, beginning with its nucleus.

grown man, but there are not so many of them. A child does not grow by making the cells of its body larger, but by making their number greater.

A cell consists of two parts: i, a soft jellylike sub¬ stance, which forms the greater part of the cell ; and 2, a darker bit of matter, called the nu'cleus , situated near the center of the cell. After a cell reaches full size, its nucleus may divide into two parts, and the rest of the cell then splits itself in half, forming two new cells, each containing half of the old nucleus. Thus a young cell is just half the size of a full-grown cell, but it is like a full-grown cell in all other respects.

Connective Tissue Between Bundles of Muscle Cells in Muscle Cells Beefsteak

(Magnified ioo times.) The connective (Natural size.) These bundles are cut tissue is white, and the muscle cells are across. The connective tissue is dark. white.

Connective Tissue. — A group of cells that look and act alike is called a tissue (tish'u). The working cells of every organ are held in place by a tissue called connective tissue. These cells are small, and have long, slender arms which are tough and strong. These arms extend around and between the cells and hold them in place. If you examine the end of a piece of beefsteak, you will find a white network of tough connective tissue lying between red bundles of soft muscle cells.

Some connective tissue is found in every part of the body. It forms the greater part of the skin.

Epithelial Tissue. — The whole skin is covered with cells which are like soft scales. These are called epi¬ thelial (ep-i-the'li-al) cells , or epithe'lium. They protect the soft and delicate flesh under them.

Glands. — The skin is always moist with a liquid called the sweat , or perspiration. The sweat comes

Diagram of a Gland

a, cells of epithelium on the surface of an organ ; b, cells of epithelium which line the tubes of the gland ; c, connective tissue which supports the gland cells.

from pores, which are the openings of deep, narrow tubes extending into the skin. Each tube is lined with cells of epithelium, which extend down the tube from the surface of the skin. The use of the cells of epithe¬ lium in the tube is to form the sweat or perspiration out of material brought to them by the blood.

A tube composed of cells of epithelium which form a substance out of the blood, is called a gland. The substance which a gland forms is called a secretion. Sweat glands are found in the skin on nearly every part of the body.

The kidneys, liver, and pancreas are glands. They are composed of tubes of epithelium which either manu¬ facture substances for the use of the body, or take waste substances from the blood.

The stomach and intestine contain glands which se¬ crete digestive juices, that is, liquids which help to change food into liquid form.

Nature of the Processes of Life. — Men used to think that the processes of life were carried on by what they called vital spirits , and that sickness was caused by evil spirits which made their home in the sick per¬ son’s body for a time. Now it is known that the work which goes on in most parts of the body is done by the same means and in the same manner as work is done in a workshop or laboratory. For example, food may be digested in a bottle in the same way as it is digested in the stomach.

There are exact means of knowing the changes which take place in the body, both in health and in disease. The study of the living actions of the body has led to the discovery of the causes of most forms of sickness and of the means of keeping the body healthy. One does not need to be a physician in order to understand these changes ; and it is the duty of every person to learn how to run the machinery of his body and how to give it the proper care.

Name one great difference between bodies which are living and those which are lifeless.

Name the two principal voluntary actions which take place in the body.