The sweat is constantly bringing waste matter out of the body. This soils the clothing next to it. On this account clothing to be washed every week or oftener should be worn next to the skin. Very thin cotton underclothing should be worn in summer. Woolen clothes give more warmth for winter.

[Ill.u.s.tration: FIG. 53.--Showing how to prevent the shoe from pressing on corns caused by wearing tight shoes or socks roughly darned.]

=Shoes.=--Badly fitting shoes cause sore feet and much pain. A shoe that is tight across the toes is sure to cause corns. A _corn_ is a thickened part of the top skin which presses on the more tender part beneath. Soaking the feet in hot water and filing off the top of the corn or using a corn plaster will help it. Shoes should always be a half inch longer than the foot. Waterproof shoes or rubbers should be worn in wet weather. Rubbers should not be worn in the house.

=Alcohol and Clothing.=--Many persons think that a drink of whisky will make them warm when taken on a cold day. For this reason whisky is sometimes used when clothing is really needed. The use of whisky or any other alcoholic drink will not make the body warm. It may make one feel warm because it loosens the muscles in the blood tubes of the skin and so lets more blood come to the surface. In this way the body becomes colder because too much blood gets into the skin and is then chilled by the cold air. As alcohol deadens the feeling it may prevent one from feeling cold when the body is really very cold. Too little clothing and too much alcohol have been known to cause men to freeze to death.

=Experience in using Alcohol to keep the Body Warm.=--Doctor Hayes, who went as physician with Doctor Kane to explore in the Arctic regions, said that he would never again take alcoholic drink with him on such a trip. He declared alcohol was of no use in helping men to keep warm. He found from actual experience that those who use alcohol cannot endure cold so well as other people.

Doctor Carpenter, a well-known physician, tells of a crew of sixty-six men who tried to stay in Hudson Bay all winter. They used some alcoholic drink. Only two of the party lived through the winter. Later another party of twenty-two men pa.s.sed the winter in the same place.

They used no strong drink at any time and as a consequence all but two of them were reported well and strong in the following spring.

CHAPTER XIV

BREATHING

=The Lungs.=--The lungs are two light spongy bodies filling up the greater part of the chest. The heart lies between the lungs. The lungs are formed largely of thousands of thin-walled sacs and two sets of tubes. One set of tubes carries air into and out of the lungs, and the other set is filled with blood. These sacs and tubes are held in place by a loose meshwork of tissue.

[Ill.u.s.tration: FIG. 54.--The ribs and front wall of the chest cut away to show the lungs. A piece of one lung is cut off to show the heart.

_A_ and _E_, parts of the breastbone; _F_, diaphragm.]

=Why we Breathe.=--Breathing means taking air into the lungs and forcing it out. The air is made to go into the lungs in order that a part of it called oxygen may get into the blood. The blood then carries the oxygen to all parts of the body where it can help the organs do their work.

[Ill.u.s.tration: FIG. 55.--Photograph of a salamander, showing the gills on either side of the head, which are used in breathing.]

The air which comes out of the lungs is not the same as that which goes in. Some of the oxygen has been used up and in its place is a heavier gas named _carbon dioxide_, which has been given out by the body. This carbon dioxide is part of the waste formed in every part of the body from the used-up food and dying parts of the body. We breathe therefore to get oxygen into the body and to take out some of the waste matter.

All animals must breathe. If our breath is shut off only four or five minutes, death results. In the earthworm the oxygen goes right through the skin into the blood. Bugs and flies have several little openings along the sides of the body which lead into tubes branching throughout the body to carry air. A fish gets air through its gills lying under a bony flap on each side of the head.

[Ill.u.s.tration: FIG. 56.--The windpipe and lungs viewed from in front.

On the right, the tissue is removed to show the air tubes.]

=How the Air pa.s.ses into the Lungs.=--The outer openings of the nose are called nostrils. From here two channels lead back through the nose to the throat. The cavity of the throat behind the nose and tongue is the _pharynx_. At the bottom of the pharynx is a tube made mostly of gristle. This tube is larger than your thumb and is named the _larynx_, or _voice box_. The b.u.mp on its front part forms the lump in the throat called the _Adam's Apple_.

From the voice box extends the _windpipe_ called _trachea_, down to the lungs. The windpipe divides at its lower end between the lungs into two branches. One of these enters each lung.

=The Air Tubes in the Lungs.=--As the branch of the windpipe enters each lung it divides into smaller branches just like the limbs of a tree. These divide into still smaller tubes, which branch again and again until they are as small as a hair. These hairlike tubes have swollen ends called _air sacs_. The walls of the air sacs are much thinner than tissue paper.

[Ill.u.s.tration: FIG. 57.--A bunch of air cells at the end of an air tube in the lungs, showing the blood vessels which receive the oxygen and give out the carbon dioxide.]

=How the Blood trades Waste for Oxygen in the Lungs.=--The blood, which is constantly running from all parts of the body to the lungs, collects waste formed from the burnt food and dying parts of the organs. When the blood comes to the lungs, it is full of this waste, called carbon dioxide. The blood tubes divide into fine branches with very thin walls and form a rich network over the air sacs. This allows the carbon dioxide and water to pa.s.s out of the blood tubes into the air sacs, while the oxygen at the same time goes through into the blood. More than a pint of water is given off in the breath daily.

=How we Breathe.=--The bottom of the chest cavity is formed by an upward arching sheet of muscle called the _diaphragm_. This is fastened to the lower ribs. The ribs at rest slant downward and inward. When the ribs are pulled up or the arch of the diaphragm down, the cavity of the chest becomes larger. The air then runs into the lungs and swells them out. When the ribs are let drop or the arch of the diaphragm goes up, the air is pushed out of the lungs.

Without thinking, we work the muscles to draw up the ribs about eighteen times every minute, because all parts of the body are calling for oxygen. The harder we work the oftener we breathe because the muscles need more oxygen to make them go.

=Why we should breathe through the Nose.=--Most persons find it easy to breathe through the nose. In some, however, the pa.s.sages in the nose are too small to carry the air without effort. On this account they let the mouth hang open and breathe through it.

[Ill.u.s.tration: FIG. 58.--Face cut through the middle to show how the adenoids stop the air from pa.s.sing through the nose. Arrows show the course which the air should take.]

The air should pa.s.s only through the nose because it is lined with hairs and tiny waving threads which catch the dust. In this way germs and dirt are prevented from getting into the throat and lungs, and in winter the cold air is warmed.

=Why Some Children cannot breathe through the Nose.=--When one has a cold, the lining of the nose becomes swollen and gives out a white substance called _mucus_. The swelling of the lining and the mucus fill up the pa.s.sages. The nose should be kept clean by using a handkerchief and blowing out the mucus into it. _Never put the finger into the nose._ Disease germs often get on the fingers from things touched.

Children who have the habit of breathing through the mouth should be examined by a physician. He will, in most cases, find soft spongy growths called _adenoids_ in the back part of the nose. They should always be removed as soon as possible. They may cause disease or deafness and may even injure the mind.

[Ill.u.s.tration: FIG. 59.--A view of the voice box from the top.]

=The Voice.=--In the upper part of the voice box at the top of the windpipe is a fold of tissue stretched on either side. These two folds of tissue form the _vocal cords_. The air rushing past them causes sound. The different sounds are made by stretching the cords tight or loosely. By means of the tongue, teeth, and lips the sound is formed into words.

=How to use the Voice.=--A cold or much shouting makes the vocal cords swell and we become hoa.r.s.e. Rest is the best cure. It is not polite to shout or whistle in the house and you should never use an angry tone of voice. When talking to a person, always speak distinctly but pleasantly and turn your face toward his and look directly into his eyes. Never use a harsh, loud tone of voice.

=Why you should not spit on Floors or Sidewalks.=--We used to think that any one well had no germs of sickness in his mouth, but we now know that many well persons have germs in their mouths which can cause long sickness when they get into other persons. If you are sick with diphtheria, scarlet fever, or sore throat, the germs of the disease are likely to remain in your mouth two or three months. Persons with tuberculosis throw out millions of these germs in their spit every day.

Spitting is not only an unclean habit but a deadly curse. Spit often contains the seeds of death. Women's skirts and the soles of our shoes carry it into the houses. It becomes dry, but the germs live and float about in the dust, then enter the mouth to make us sick. Carelessness with spit is said to cause more than a hundred deaths every day in our land.

=Do not use an Open Spittoon.=--It is much safer to have a smallpox patient in the house than an open spittoon in the summer. You can prevent the smallpox by vaccination, but you cannot keep the flies from carrying ten thousand germs of death from the spittoon to the food on the table. A million germs have been found on a single fly.

[Ill.u.s.tration: FIG. 60.--Photograph of a house fly on a piece of bread.

This fly had been feeding on spit and a study of its legs and body showed more germs present than there are hairs on a person's head.]

Spit should be dropped into a cup which should be kept covered when not being used. The spit should be destroyed by fire or some germ-killing fluid, such as lye or formalin.

[Ill.u.s.tration: FIG. 61.--An exact drawing of the germs in a spot as large as a period, on the edge of a drinking cup.]

=Keeping Sickness away from the Throat and Lungs.=--All sickness of the throat and lungs is caught from some one else. The germs are pa.s.sed from one to another on the drinking cup, by sucking pencils, wetting the finger to turn the pages of a book, or putting the fingers in the nose or mouth.

[Ill.u.s.tration: FIG. 62.--A dish of beef broth jelly left open two minutes in a room being swept. Each spot is a city of thousands of germs which grew from one germ dropping on the jelly. By counting the spots you can tell how many germs fell from the dust on this dish three inches in diameter.]

_Dust is the partner of disease._ It contains germs. Avoid dust. Wipe up the rooms with a damp cloth; never use a feather duster. Avoid dry sweeping. Use a suction cleaner or have rugs which can be cleaned out of doors.

Give the lungs fresh air and deep breathing and the body good food and plenty of sleep to make it so strong that germs cannot overcome it when they enter.

[Ill.u.s.tration: FIG. 63.--Photograph of consumption germs, the tiny rods which often grow and cause tuberculosis in bodies weakened by beer or whisky. Much enlarged.]

=Alcoholic Drink and the Lungs.=--The most common disease of the lungs is _tuberculosis_. Nearly all bartenders who sell strong drink take some themselves. Lately it has been learned in Germany that tuberculosis causes one half of all the deaths among bartenders.

Alcohol was once thought to be a good medicine for lung troubles, but it has been clearly proven that beer and whisky weaken the lungs and make them ready for the germs of disease. The body already weakened by the poison of the alcohol is then easily overcome by the disease.

=Tobacco and the Lungs.=--The occasional use of tobacco does not seem to hurt the lungs when fully grown. A study of many young persons has shown that the chest of smokers grows much more slowly than in those who do not use tobacco. As the lungs cannot grow any faster than the chest, they must grow slowly in boys using much tobacco.

Tobacco is a common cause of sore throat. Many smokers have been compelled to quit the habit because of throat troubles.

PRACTICAL QUESTIONS