CHAPTER VICARE OF FOOD—MILK

Dangers from diseased meat

Sometimes butchers are anxious to make money fast and take little thought for the number of people they maymake ill. They can buy sick cows very much cheaper than well ones. The meat from a sick cow looks just like the meat from a healthy cow, and the dishonest butcher sells both at the same price. The meat from the diseased cow is not suitable for food. It may cause you to have the same disease that the cow had, or it may only be changed to such an extent that it will not give you the nourishment that you should get from good meat. The butcher who sells you meat from a sick cow is of course dishonest.

Fig. 11.Improperly displayed foods, exposed to handling and to dirt and flies.

How to prevent the sale of diseased meats

Ask your father to visit the slaughterhouse where your meat is killed. The only thing you need to do is to persuade him to go and see whether the cattle are sick or not. If the cattle look sick, you will not have to ask him not to buy the meat. No person should ever eat meat that comes from a diseased animal, no matter what the nature of the sickness may be. People who will take the trouble to visit the slaughterhouses occasionally, to investigate these things for themselves, will not have such meat offered them.

Importance of giving animals clean food

Animals that are fed on filthy food are not fit for human consumption. Butchers often feed the offal (the insides) of animals to the hogs. This makes the hogs fatten quickly, but it also makes them diseased. When you go to the slaughterhouse with your father, ask him to go around to the back door, and if you see hogs eating this filth, do not buy any more meat from that butcher.

Questions.1. What use does the body make of meat? 2. What conditions are essential for good meat? 3. How can meat be kept clean? 4. Why is meat from a diseased animal unfit for food? 5. How can you help in preventing the sale of meat from diseased animals? 6. Why should animals not be fed with offal?Remember.1. Meat that is not handled in a clean manner is sure to contain germs that cause a poison to form in the meat. 2. Never buy meat from a butcher who does not keep his slaughterhouse and butcher shop clean. 3. Meat from a diseased animal is not fit for food. 4. Meat from animals fed on filthy food should not be eaten. 5. Form a "Clean Meat League" and visit the slaughterhouse where your meat is killed.

Remember.1. Meat that is not handled in a clean manner is sure to contain germs that cause a poison to form in the meat. 2. Never buy meat from a butcher who does not keep his slaughterhouse and butcher shop clean. 3. Meat from a diseased animal is not fit for food. 4. Meat from animals fed on filthy food should not be eaten. 5. Form a "Clean Meat League" and visit the slaughterhouse where your meat is killed.

Value of milk as a food

Milk is another important article of food. The Department of Agriculture at Washington says that milk furnishes sixteen per cent of the nourishment of the people of the country. Milk is an excellent food when it is pure, but when it is not pure it is very dangerous.

Fig. 12.A clean dairy.

Milk as a carrier of germs

Milk has carried the germs of every disease of which the germ is known; it has also carried many diseases of which we do not know the germ. Disease germs grow rapidly in milk, and they do not make the milk look different or taste different from milk that is perfectly pure. If you could take two bottles of milk entirely free from disease germs and put typhoid fever germs in one, and should set both bottles in an ice box for twenty-four hours, you would not then be able to tell into which one you had put the germs. The milk in both bottles would look and taste just the same. The only difference between the milk in the two bottles would be that if you drank from one it would make you stronger and would furnish you with bothbuilding material and power-producing material, while if you drank from the other you would become very ill and would probably die.

How disease germs get into milk:

Since we cannot tell from the taste or the appearance of milk whether or not there are disease germs in it, we must take every precaution possible to keep them out. The first step is to learn where the disease germs come from and how they get into the milk.

Fig. 13.Polluted milk is sure to come from a dairy where cleanliness is not observed.

(1) By dirt on the cow

Every cow has more or less dirt on her sides and udder; some have a great deal. When the cow is milked, much of the dirt falls into the milk bucket. This dirt always contains a great many germs of different kinds, and many of them are germs that cause disease. Straining the milk will take out much of the dirt, but disease germs will go through the finest strainer that was ever made.

In Figure 13 we see a man milking a dirty cow. The owner has allowed his lot to become so dirty that the cow cannot find a clean place in which to lie down. If the man kept his lot clean, and if before milking the light dirt on the cow's sides and udder were wiped off with a damp cloth, no germs would fall into the milk.

(2) By dirt in the cow barn

Another source of dirt and disease germs in milk is the barn. The walls of a barn where cows are milked should always be kept clean and should be whitewashedfrequently. If this is done, there will be comparatively little dirt on the walls to fall into the milk.

Fig. 14.Only clean milk will come from a dairy where proper precautions are taken.

Of course the walls and floors of a barn cannot be kept absolutely clean. There will always be some dirt, and the movements of the cows shifting their position and switching their tails, will stir up the dust; so it is important to remove the milk from the barn as soon as possible. Milk cans should never be kept in the barn. The milk should be taken directly from the barn to a cooling house and there strained.

All barns where cows are kept should have plenty of windows, that there may be an abundance of light and fresh air. Cows need fresh air just as much as people do, while a barn that is not supplied with plenty of light is very likely to be a dirty barn.

Keep dirt and disease germs out of the milk by keeping the barn clean and by taking the milk away from the barn as soon as possible.

Fig. 15.A dirty, insanitary milk-house.

Fig. 16.A clean, inexpensive milk-house.

(3) By dirt on the milkman

Another source of dirt and disease germs in milk is the milkman or milkmaid. No matter how careful we may be, our clothes hold more or less dust, and all dust contains germs, very often disease germs. When a person is milking a cow, the dust from his clothes is shaken off into the milk. The only way to avoid this is to wear, while milking, a special suit of clothes made of white cloth, which may be washed as soon as it shows the least particle of dirt.

The milker's hands, too, are often dirty. Perhaps he carefully washes his hands after milking, but not before. It is a common custom for milkers to moisten their hands with milk while milking, and to do this frequently. The result is that dirty milk from their hands is constantly dropping into the milk pail. This is a very bad habit,and doubly bad if the milkman has not washed his hands before milking.

Sometimes there are sick people at the dairy farm. Often some one nurses a sick person until milking time and then goes out and milks the cows. When this is done, the milker is almost sure to plant the germs of the disease in the milk. No milk should ever be used from any dairy where there is an infectious disease; and no one who has charge of a sick person, no matter what the nature of the sickness, should ever handle milk that is to be used by others.

Fig. 17.A model bottling establishment.

(4) By dirt in cans and bottles

The cans and bottles in which the milk is placed are frequently sources of dirt and germs. Milk cans and bottles are supposed to be thoroughly washed before milk is put into them, and they should be thoroughly scalded after they are washed. This is not always done, and sometimes the bottles are not washed at all.

Some dairymen will tell you that the bottles and cans are always washed and scalded just before the milk is put into them, and that this is never neglected by any dairyman. That is what a dairyman once told me. Then I asked him how he accounted for the fact that I had founda milk ticket in the bottle with the fresh milk. Of course he could not explain this, though I thought I could explain it for him. The old milk bottle was returned to the milkman with the ticket for the new milk inside it. The deliveryman left the fresh milk, but forgot to take the ticket out of the bottle; and the man who "washed" the bottles must have forgotten to take out the ticket too. Of course, the bottle was not washed at all, and if one bottle goes unwashed, it is reasonable to assume that others are neglected in the same way.

Milk bottles and cans should always be thoroughly washed before fresh milk is put into them. This washing cannot be done by little children; it is work for a man or woman, and careful work at that.

(5) By polluted water

I have just told you that milk vessels should be thoroughly washed. It is true, however, that disease germs may get into the milk through this very process of washing the vessels. Water sometimes contains disease germs, especially the germs that cause typhoid fever, cholera, and other diseases of the intestines. Such water is said to be polluted. When milk vessels are washed with polluted water, the germs are left in them and thus get into the milk. If the water used to wash the cans is thoroughly boiled, the germs will be killed; hence it is important to scald all milk vessels.

All water used about a dairy should be perfectly pure. If there is the least suspicion about the quality of the water, it should be examined by a chemist; and if it is not pure, the milk from such a dairy should not be used. In order to prevent the possibility of any infection, all water used to wash milk vessels should be thoroughlyboiled even when the water is known to be pure, and the vessels should afterward be scalded, to kill any germs that may be left after washing.

(6) By flies falling into the milk

Flies very frequently get into the milk. Later we shall learn more about how flies carry germs, but at present it is enough to know that on every fly there are a great many germs, and whenever a fly gets into milk it plants those germs and they grow very rapidly. As soon as a cow is milked, the milk should be taken to a clean cooling house, with screens at all the windows and doors, and there strained into a vessel and cooled.

(7) By disease in the cow

The last way that we will mention by which germs get into milk is by disease in the cow herself. Cows suffer from many diseases, just as men do; and when a cow is sick, her milk is very likely to contain the germs of the disease that is making her sick. Especially is this true of tuberculosis, or consumption, as it is called. A great many children get consumption by drinking milk from consumptive cows. No milk should ever be used from a cow that is not healthy. All dairy cows should be examined at frequent intervals by a competent veterinarian to make sure that they are free from any disease.

Questions.1. Milk forms what per cent of the food of the people of the United States? 2. Why is it important that milk should be kept clean? 3. Name some ways by which germs get into milk. 4. What is the danger from a dirty cow and barn? 5. How can this danger be prevented? 6. How does the milkman allow germs to get into the milk, and how can he avoid doing so? 7. How should milk cans and bottles be washed? 8. Why is it important that only pure water be used about the dairy? 9. How can flies be kept out of milk? 10. How should milch cows be tested to make sure that they are free from tuberculosis?Remember.1. Milk is a very important article of food; it is both a building and a heat-producing material. 2. When milk is not properly handled, it contains many disease germs. 3. Disease germs often get into milk from unwashed bottles and cans; from dirty barns; from dirty milkmen; from dirty water used to wash the cans and bottles; from flies falling into the milk; from diseased cows.

Remember.1. Milk is a very important article of food; it is both a building and a heat-producing material. 2. When milk is not properly handled, it contains many disease germs. 3. Disease germs often get into milk from unwashed bottles and cans; from dirty barns; from dirty milkmen; from dirty water used to wash the cans and bottles; from flies falling into the milk; from diseased cows.

Fig. 18.Partially decayed fruit is not fit for food.

Why partially decomposed foods should not be eaten

Vegetables and fruits that are partially decayed should not be eaten. Even if an orange is decayed only on one side, the products of decomposition—that is, the poisons produced by decay—have extended all through the orange. You cannot see them, but they are there. It is the same with a decaying apple, potato, or melon. It never pays to buy partially decayed or stale fruits or vegetables, for not only are they dangerous to health, but they are so reduced in nourishing qualities by decomposition that you get little value for the money you spend. It is always better economy to buy fresh fruits and vegetables, or even canned vegetables, when the latter are properly put up.

What causes decomposition

All decomposition (rotting) in fruits and vegetables is due to the action of germs. If you will look at a bunch of old grapes, you will notice that some of the grapes are rotten, while others have dried up. Now, if you examine them very carefully, you will find that all the decomposed grapes have breaks in the skin. The break may be very small, but it is there, and through this break the germs that cause decomposition have entered. You will find also that there is not the slightest break in the skin of any grape that has dried up. The germs could not enter, hence there has been no decomposition. It is the same with other fruits and vegetables: if the germs that cause decomposition cannot get inside, the fruit or vegetable will dry up, but will not rot.

Fig. 19.Fruits displayed for sale, but properly protected from flies, dust, and dirty hands.

Germs can go through a very small opening—so small that you may not be able to find it; but if there is decomposition, the hole is there.

The skin of the body acts in the same way as the skin of the grape and keeps out a great many germs that would make us sick were they able to get through the skin. They often get through the skin when we cut ourselves.

Meats decompose as well as fruits and vegetables, and the decomposition is due to the presence of germs in the meat. We cannot keep all germs out of meat, but we can keep out a great many of them by having everything clean about the meat, by keeping it covered as much of the time as possible, and by handling it only with clean hands.

Fig. 20.Fruits for sale, not properly protected from flies, dirt, and other sources of filth.

Why foods do not decompose in very cold places

When meat is kept so cold that it is almost frozen, the germs cannot grow, and decomposition is prevented. In this way meat can be kept perfectly free from decomposition for several weeks. After the meat is taken fromthe cold storage room, it should be cut as soon as possible into steaks, roasts, and other pieces for cooking; and when taken to your home, it should be kept in an ice box until the time to cook it. You cannot keep meat very long at home without decomposition starting, because small ice boxes are not cold enough to check entirely the growth of germs.

Unless the meat is to be eaten hot, it should be cooled after cooking and placed again in the ice box as soon as possible. Cooking kills the germs that are in the meat before it is cooked; but unless it is kept in a very cold place and protected from flies after it is cooked, germs will get into it again as soon as it is cold. Cooked meat will decompose just the same as uncooked meat.

What is formed in food by decomposition

When germs are allowed to grow in meat, as always happens when it is not kept in a very cold place, these germs cause the poisons that we call ptomaines. The people who eat such meat become sick, and in many cases do not recover. Cooking meat that contains ptomaines will kill the germs that caused the poison, but it will not destroy the poison that has already been formed.

Why some canned meats are poisonous

People not infrequently are poisoned by eating canned meat. Sometimes you will hear it said that the poison formed because the meat was in cans. This is not true; the cans had nothing to do with the forming of the poison. This was caused by germs that were allowed to grow in the meat before it was cooked. When the meat was cooked the germs were killed, but the poison was not destroyed. In other words, the poison developed before the meat was canned, and not after it was put into the cans.

Questions.1. What is the objection to eating fruits when they are partially decayed? 2. Why do some foods shrivel while others decay? 3. Why does decomposition not go on in cold places? 4. What are ptomaines? 5. When are ptomaines formed in canned meats?Remember.1. Partially decomposed fruits or vegetables are not suitable for foods. 2. Meats in which germs have been allowed to grow should not be eaten. 3. Cooking meat kills the germs in it, but does not destroy the poisons that the germs have formed. 4. When canned meats are poisonous, it is because the poison was formed before the meat was canned; the poison is not caused by the can.

Remember.1. Partially decomposed fruits or vegetables are not suitable for foods. 2. Meats in which germs have been allowed to grow should not be eaten. 3. Cooking meat kills the germs in it, but does not destroy the poisons that the germs have formed. 4. When canned meats are poisonous, it is because the poison was formed before the meat was canned; the poison is not caused by the can.

Effects of improper cooking

Nearly all food should be cooked before it is eaten; but if the cooking is not properly done, much of the nourishing power of the food is destroyed, and in some instances the food is rendered actually injurious.

Why starchy foods should be thoroughly cooked

Starchy foods should be thoroughly cooked in order that the coverings which surround the little granules may be broken or made soft. If starchy foods are not thoroughly cooked, the little grains go into the stomach as hard as grains of sand; then most of them are not digested at all, but pass out of the system without furnishing any nourishment to the body. If starchy foods are fried in fats, as is the case with doughnuts, the granules of starch become coated with fat. As the fat is not digested until it comes to the intestines, the saliva never reaches the coverings of the starch, and more work is thrown on the other juices of the body. The result is that the little glands which make these other juices are overworked, or else the starch is not digested at all and therefore furnishes no nourishment to the body. When bread is sticky (we sometimes call it soggy) in the middle of the loaf, it is because the flour has not been thoroughly cooked and the little grains or granules of starch are still hard. You cannot feel these granules between your fingers, but they are hard just the same, and very little of such food is made use of in the body.

Remember that all starchy foods should be thoroughly cooked, and remember, too, that all vegetables are chiefly starchy in character.

How fats should be cooked

When fats are cooked over a very hot fire, an acid is developed that is injurious to the body. This does notmean that when the fire is hot enough to broil a steak well, it causes this acid to form; neither does it mean that heat sufficient to boil the grease for cooking doughnuts will cause it to form. Every cook knows that when she fries fat meat over a fire that is too hot, it has a bitter taste. This bitter taste is caused by an acid which will destroy a part of the usefulness of the food in the body and will cause many of the cells to stop doing their work properly.

How meats should be cooked

There is a great difference of opinion in regard to cooking foods, especially meats. Some people will tell you that meats should not be cooked at all; that man originally ate his meat raw and that this is the proper way. Others will tell you that all meat should be cooked until it does not show a particle of red, even until it is dry throughout. These are the two extremes; and it is never well to go to extremes in anything, especially in matters that concern the health.

Meat should always be cooked, because by being cooked it is made more easily digestible; but it should not be cooked, until all the juices, which contain much of the nourishing matter, are dried up and the meat made hard. Meat that is cooked until it is dry and hard is more difficult to digest than meat that is not cooked at all.

Questions.1. What effect has improper cooking on foods? 2. Why should starches be thoroughly cooked? 3. What is the objection to starchy foods fried in grease? 4. What changes take place in fatty food when it is fried over a very hot fire? 5. Why should all meats be cooked? 6. What is the objection to cooking meat until the juices are dried out?Remember.1. Starchy foods should be thoroughly cooked so that the fine grains may be softened and the food thus made more easy to digest. 2. Fats should not be fried over a very hot fire because too much heat causes a poison to form in the fat. 3. Meats should be cooked, but never until they become dry, as the juices in the meat contain most of the nourishing material.

Remember.1. Starchy foods should be thoroughly cooked so that the fine grains may be softened and the food thus made more easy to digest. 2. Fats should not be fried over a very hot fire because too much heat causes a poison to form in the fat. 3. Meats should be cooked, but never until they become dry, as the juices in the meat contain most of the nourishing material.

Why mealtime should be pleasant

The dining table should be the pleasantest and most inviting place in the house. If you are complaining and quarreling during the meal, you cannot enjoy the food; you cannot eat it properly; and your ill temper will so affect your body that you cannot properly digest what you eat. A dirty table, with flies swarming over the food, is not very tempting, and when seated at such a table, one does not eat the things that are best for him and sometimes does not eat anything at all.

Fig. 21.A clean, inviting dining-room.

How uninviting luncheons affect the appetite

The luncheons that boys and girls take to school with them are often prepared in so careless a way that they are extremely uninviting. The substantial school lunch can be made just as appetizing as the dainty refreshments at an afternoon tea or at a party. If the same care is devoted tothe preparation of the one as of the other, boys and girls will eat their lunches with enjoyment and good appetites.

Why an attractive table calls for pleasing guests

If the table is made to look clean and inviting, do you not think that you, in your turn, should make yourself as neat and clean as possible before you come to it? Dirt on your hands and face not only does not look well, but contains a great many germs that may get into your food and thus find their way into your body and try to make you ill.

Fig. 22.Two lunches. Which is the more tempting?

How foods should be eaten

Besides being eaten in pleasant surroundings, all food should be eaten slowly. Let us suppose that we are all seated at a clean, inviting table and everyone is clean and happy. Before the children is the very kind of food that is best for them. It looks good and they know it is good, and they want to eat all they can of it. But they think of a game of jacks or of ball that they want to play as soon as dinner is over, so they simply "bolt" their food.

What are teeth made for? Why, to chew with, of course. But why are we given some teeth that are sharp like knives, and some that are flat like millstones? Itseems probable that these different kinds of teeth are intended for special purposes, and so they are. If our teeth were intended only for cutting our food into bits small enough to swallow without causing pain, there would be no need for any except the sharp, knife-like teeth. But we have the big grinders, which were made to use, and it is very important that they be used in the right way.

Why food should be thoroughly chewed

We do not chew our food simply to make it fine enough to swallow, but for quite another reason as well. In our mouths there is a fluid calledsaliva. Think of something that you are very fond of eating, and the mere thought of it makes the saliva come into your mouth. This saliva has a very important duty to perform in connection with preparing the food for the little cells of the body. Each little grain of starch—and you will remember that all vegetable foods are composed largely of starch—has a capsule about it. This simply means that it is done up in a little package. The saliva helps to open this capsule by making it soft (just as water will soften the paper on a package of candy), so that the other digestive juices can reach the starch and turn it into the kind of sugar that is used in the body. If you do not chew your food very fine, the saliva will not reach the starch granules, the little packages of starch will be hard to open when they go into the stomach, and much of the starch will never be made use of in the body. The saliva has much the same action on the coverings of the little packages of meat, for all the meat that we eat is done up in similar packages.

A great Englishman, Mr. Gladstone, who lived to be eighty-three, made a practice of chewing every bite offood twenty times, and he thought this had a great deal to do with his being such a strong and well man and living to such an old age.

When desserts are not harmful

After you have eaten meats, bread, and vegetables, it will do no harm to eat a piece of pie or cake, or a dish of ice-cream or some other dessert. It is not easy, as a rule, to digest these things (that is, to get them into such shape that they can be used as food by the little cells in the body), but a moderate amount of them is very good for boys and girls, as well as for grown people. If you refuse to eat the meat and bread, but wait until the dessert is served and then fill your stomach with sweet things, you will be starving some of the little cells, and you will be reminded of this very soon. Sometimes you may be reminded of it by having a pain in your stomach, but more often by getting low grades in your lessons at school. Your teacher will know it, too, because you will be so restless and inattentive in your classes that she will have to give you a low grade in deportment as well.

Questions.1. What kind of topics should be discussed at mealtime? 2. What is the objection to an untidy table? 3. What kind of luncheon do you like best? 4. What does a clean table call for? 5. What is the importance of eating slowly? 6. Why should we chew our food thoroughly? 7. When are desserts not harmful?Remember.1. The dining table should be the most inviting place in the house. 2. Unpleasant subjects should be avoided at mealtime. 3. A clean table calls for clean people. 4. Eat slowly and chew your food thoroughly, that the saliva may reach each grain of starch. 5. Desserts are not harmful if eaten at the end of a meal composed of good building and heat-producing materials.

Remember.1. The dining table should be the most inviting place in the house. 2. Unpleasant subjects should be avoided at mealtime. 3. A clean table calls for clean people. 4. Eat slowly and chew your food thoroughly, that the saliva may reach each grain of starch. 5. Desserts are not harmful if eaten at the end of a meal composed of good building and heat-producing materials.

We have learned that chewing is not merely a process of cutting our food into such lumps as we can swallow without hurting ourselves; but that the food must be ground up fine and thoroughly mixed with the saliva, that the saliva may reach every particle of starch. If we do not have good teeth, we cannot grind our food as fine as it ought to be ground, and, as a result, a great deal of the starch will not be reached by the saliva.

Nature starts every child with a full set of good, strong, clean teeth. These teeth, which we call first, or milk, teeth, are not very large, but they are perfect in every respect and last until the second, or permanent, teeth come in. That is, they will last so longif they are taken care of. If they are not taken care of, they will decay just as the later teeth will decay, and they must be cared for in the same way.

Why we have baby or milk teeth

Boys and girls sometimes wonder why they have a set of teeth that come out before they can have the teeth that must last them the rest of their lives. This is simply because there is not room enough in a child's mouth for the big, permanent teeth. We must have teeth while our jaws are growing, so we have first a set of little teeth. Then just as soon as our jaws get large enough for the big teeth, the little teeth come out and the big ones come in.

Teeth are about the hardest substance in the body. If we take care of our second teeth, they should last as long as we live. The only reason they do not last is because we do not take care of them. If a person would keep his teeth clean all the time, he would rarely be obliged to have a single permanent tooth pulled.

Why teeth break easily

Teeth are so hard that they are brittle, that is, they break easily. Glass is brittle, and you can chip off a piece of glass with a pin by sticking the pin into a crack in the glass. In just the same way you can chip off a piece of a tooth by sticking a pin between two teeth. That is what often happens when people pick their teeth with pins, or with any other hard substance. A metal toothpick is just as bad as a pin.

Fig. 23.Teeth were not intended for nutcrackers.

Another way by which little pieces are chipped off the teeth is by biting hard things. Sometimes we see boys and girls cracking nuts with their teeth; again we see them trying to bite wires in two. They put their teeth to many uses for which teeth were never made. They do not realize, while they are abusing their teeth in this way, that they are probably chipping the enamel, which is the hard, shiny covering of the tooth, and are destroying the one protection that their teeth have against decay.

Why teeth decay

When a little piece is chipped off a tooth, an opening is made through the enamel. Through this opening germs may lodge in the inner part of the tooth, which is soft. When this happens, a little black speck appears on the tooth, and after a while the tooth begins to ache. If you have a toothache, you go to a dentist, and he probably finds that germs have caused the tooth to decay until there is a hole extending into the very center of it.

Teeth grow very close together, but there is always a little space between them. Whenever you eat anything,particles of the food get into these spaces and if allowed to remain there, soon decompose. These decomposing particles of food between the teeth will gradually soften even the enamel, and in this way little openings are made for germs to get into the teeth.

How to care for the teeth

Never pick the teeth. You cannot make them clean by picking them. Every morning and night brush your teeth with a stiff toothbrush and a little tooth powder. Brush them both crosswise and up and down, to get out everything from between them. Do not think you have done your duty if you brush only your front teeth, the ones that show. Brush the back teeth just as thoroughly as you do the front teeth. Very few people will see your back teeth, but these decay just as fast as your front teeth, if they are not kept clean.

Fig. 24.A sanitary wash-basin with a separate bowl for washing the teeth.

How often one should go to the dentist

Twice each year you should have a dentist examine your teeth, to see if there are any little spots where decay has started. If you have kept your teeth perfectly clean all the time, and have not chipped off little pieces, there will be none of these decayed spots. But it is a safe plan to have the teeth looked over at least twice a year, for you may have broken a tooth without knowing it, and by the time a decayed spot is large enough to cause pain, or has made a hole that you can feel with your tongue, it has advanced much farther than it should have been permitted to do.

Questions.1. Why should you chew your food thoroughly? 2. Why is it necessary to have baby teeth? 3. How are teeth easily broken? 4. Why do teeth decay? 5. What must you avoid in order to protect your teeth? 6. How should your teeth be brushed? 7. Why should you have your teeth examined twice each year by a dentist?Remember.1. Take care of your teeth and they will last you as long as you live. 2. Do not pick them with pins, or toothpicks of any kind. 3. Do not use them for nutcrackers or wire-cutters. 4. Do not use them for tack pullers. 5. Keep them clean at all times. 6. Brush them up and down as well as crosswise.

Remember.1. Take care of your teeth and they will last you as long as you live. 2. Do not pick them with pins, or toothpicks of any kind. 3. Do not use them for nutcrackers or wire-cutters. 4. Do not use them for tack pullers. 5. Keep them clean at all times. 6. Brush them up and down as well as crosswise.

We have learned how the cells of the body are killed by starvation. Now let us learn how they are choked to death, or killed by lack of air.

How air is changed in the body

The cells of the body needoxygen, and the only way we can give it to them is by means of air. Every time we take air into our lungs we are giving oxygen to the red corpuscles or cells in the blood, which distribute it to the other cells in the body. The air that goes into our lungs, if it is fresh and pure, contains a great deal of oxygen and a very little of another gas calledcarbon dioxid. The air that comes out of the lungs contains a very little oxygen and a great deal of carbon dioxid. The blood not only takes the oxygen out of the air, but gives carbon dioxid to the air. This carbon dioxid is very poisonous, and would kill the cells if it remained in the blood; hence we should never breathe the same air twice. There is no lack of fresh air in the world, and no excuse for anyone's ever breathing air that is not pure.

Effects of impure air

If you close all the windows and doors in the schoolroom and shut up the ventilators, you will soon find that you are not able to pay close attention to your studies, and in a little while you will begin to feel drowsy. This is because you have used up so much of the oxygen in the air that there is no longer enough to supply the demands of the little cells, and because, in addition, you are taking into your bodies the poisonous carbon dioxid that has been breathed out into the room. It takes a great deal of fresh air to supply the body with oxygen—about 1,250 cubic feet of air each hour. With thirty or forty children in a room, it doesnot take long to use up all the oxygen. So there should be a constant supply of fresh air coming into the room.

Fig. 25.Results of breathing good and bad air.

Methods of ventilation

It is not only in the schoolroom that you need oxygen. When you are out-of-doors you get an abundance of fresh air, but from a great many houses every bit of fresh air is shut out. It is always possible to let an abundance of fresh air into any house without causing a draft. A piece of board can be made to fit into a window frame so that when the window is raised, the air will be directed upward and will not cause a draft. Hot-air furnaces are made with cold-air pipes. The fresh air from outdoors comes through these cold-air pipes and, after being heated, is driven into the rooms of the house. Some people think they will save coal by closing these drafts. Not only do they not save coal (for the furnace does not give as much heat when this draft is closed), but they kill their body cells by refusing to give them oxygen. The cold-air pipe in a hot-air furnace should always be kept wide open.

In houses heated with steam or hot water, either the windows must be kept open, or some other way must be provided for admitting fresh air and taking out foul air. These arrangements constitute a system of ventilation. Houses heated with stoves must also be provided with some meansof ventilation. The stove, by its draft, takes out a little of the foul air, but it will not take out more air than one person poisons.

Fig. 26.Restfulness: Effect of good ventilation in a sleeping-room, with the right position for sleeping.Fig. 27.Restlessness: Effect of poor ventilation in a sleeping-room, with the wrong position for sleeping.

Fig. 26.Restfulness: Effect of good ventilation in a sleeping-room, with the right position for sleeping.

Fig. 27.Restlessness: Effect of poor ventilation in a sleeping-room, with the wrong position for sleeping.

Why windows should be kept open at night

Many people seem to think that they do not need fresh air at night, and they close their bedroom windows as tight as they can. Those people do not sleep well and often have bad colds. You should always sleep with your windows open. If it is impossible for you to have your windows open without having a draft, choose the draft; it will do you no harm if you are well covered, and under no circumstances will it do you as much harm as the foul air that you breathe if your window is closed. Some persons (fortunately they are few nowadays) will tell you that night air is dangerous. I wonder what kind of air these people expect to breathe at night. Do they expect to fill the roomin the daytime with enough air for use at night? Such air would certainly not be very fresh. Night air is the only kind of air that it is possible to breathe at night.

The ventilation of public assembly rooms

Churches, theaters, and ten-cent shows are often very poorly ventilated. You can always tell a poorly ventilated room by the foul odor when you go into it from the fresh air, and it is not wise to stay in such a room. You are killing the cells in your body when you do so, and you will very probably come out of it with a bad cold. When the fresh air strikes you, you feel chilly and you may think you are taking cold then, but in reality you took cold in that room full of foul air.

Ventilation of workshops

Workshops are often poorly ventilated. No person should ever work in a badly ventilated place. The labor unions frequently strike for higher wages, but until recently a strike for better ventilation was rarely heard of. Better ventilation would be practically equal to an increase in wages, because there would be fewer doctors' bills to pay, and less likelihood of losing work through illness. Always have plenty of pure, fresh air wherever you are—in school, in bed, at work, or at play.

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