Our Unseen Enemies
( Originally Published 1920 )
Daniel Boone, the Indian Fighter.—Did you ever think that the place where you now live was once upon a time deep forest or open prairie, with no houses or farms but only wild beasts and a few Indian huts? Perhaps it is a great city now with tall buildings and trolley cars; or it may be a pleasant countryside of rich farms and peaceful villages. A hundred years ago, however,—or two hundred or three hundred,—it was all wild country. The first explorers were in constant danger from the forest creatures and the Indians, and they knew they might have to fight for their lives and the lives of their families at any hour of the day or night. Perhaps you have seen pictures of the Puritans in New England going to church on a Sunday morning, each man with his gun on his shoulder, ready in case an Indian attack should come.
After the Atlantic states had been settled, the white men pushed farther and farther west. In each place the brave pioneers took possession of the new lands at the risk of their own lives. One of the most famous of these pioneers was Daniel Boone. He was born over a hundred and fifty years ago in Pennsylvania; but he soon sought for adventure in the unknown lands to the west. He and five other companions pushed out into the wilderness of what is now Kentucky. Boone was taken prisoner by the Indians, but made his escape and lived for nearly two years in the forest, part of the time alone and part of the time with his brother, who had followed him from their home. The Boones were mighty hunters and trapped and killed bears and other wild animals, so as to make furs out of the skins.
In 1775 Daniel Boone went out with a large party and built a fort of logs at the place now called Boonesborough. Three times this fort was attacked by the Indians, and the last time there were four hundred and fifty of them against Boone's little force of fifty men.
Can you imagine the wooden fort with narrow loop-holes through which the guns of the white men were pointing, as the Indians came dashing out of the forest to the attack? No enemies had any terrors, however, for Boone and his companions. They beat off the Indians, even though they were nine to one against them; and after this the fort at Boonesborough was never attacked again.
We ought always to remember gratefully these brave men who went out' into new lands and killed the wild beasts and cut down the forests so that we could have farms and villages and cities and enjoy them in peace.
Our Enemies of Today.—We do not have to fight wild animals any more. Daniel Boone and other pioneers have driven them away, so that we can live in peace so far as they are concerned. There are still enemies about us, however, in every city and town and country village. You never hear your father say that Mr. Smith or Mr. Jones has been killed by a bear, as Daniel Boone's children must have sometimes heard their father say when he came home from hunting. But you do sometimes hear that Mr. Jones or Mr. Smith has died of typhoid fever or tuberculosis or pneumonia. It is against these diseases that we must fight, as our great-grandfathers or great-great-grandfathers fought against wild beasts in earlier days.
There are some kinds of sickness that we cannot avoid. When a person grows old, he gradually becomes less and less vigorous and at last is sure to suffer from sickness of some kind. In youth and even in childhood certain people are naturally not so strong as others. There is another class of diseases, however, which are not the result of any necessary weakness of the body but are caused by something which comes from out-side, an enemy just as real as the Indians who attacked the fort at Boonesborough; and such diseases can be avoided.
The enemies which cause the diseases we are thinking about are the tiny living things called microbes or germs, discussed in Chapter IX. They are so small, you remember, that we cannot see them at all, except by using a very powerful microscope. They are smaller even than the cells of the blood that were described on page 123. Yet it is these microbes that cause some of the commonest diseases from which people suffer from colds to diseases like tuberculosis,—and sometimes they produce great epidemics that kill hundreds of thousands of people, as the influenza did in 1918. Such microbes kill more people in the United States in one year than the Indians ever did in the whole history of the country.
Fighting the Microbes of Disease: You have probably seen a jar of jelly or preserves that had become spoiled, with patches of mold on the top of it. This mold is a microbe, which grows in masses so large that you can see them; and microbes produce disease very much as the mold microbe spoils the jelly. Each kind of microbe causes its own particular sickness—one, diphtheria; another, measles; another, scarlet fever; another, whooping cough. When a child has diphtheria, for instance, it is simply because the germ of diphtheria has gotten into his throat and is growing there and poisoning his whole body. If we could keep out the microbes, that child would never have diphtheria; and in the case of many such diseases, we have learned how to protect ourselves very effectively from these invisible enemies.
The man who first showed how to conquer the diseases caused by microbes was a great Frenchman named Louis Pasteur (pâs tûr'). Fifty years ago no one knew the cause of typhoid fever or tuberculosis or any of the other diseases of this kind. People fell sick, sometimes one or two at a time, sometimes by hundreds and thousands, and there was little that any one could do to protect them. It was like fighting against Indians that you could not see at all. What chance would there be if invisible enemies could shoot off their arrows at you, and you could never tell where they were and could never see them to strike back?
It was Pasteur who first revealed to us our microbe enemies. By the use of the microscope, he found that in the bodies of animals and men suffering from certain diseases tiny living germs were growing. At first no one would believe that they had anything to do with causing sickness; but Pasteur worked patiently on and showed that in each of these diseases there was a special kind of microbe, and that this particular microbe was, in each case, the cause of the disease.
Microbes as Friends and Foes.—There are many different kinds of microbes, and only a few can pro-duce disease. There are microbes all about us, a few floating in the air, a few in the water we drink and the food we eat, more in the dust on the floor, a great many in the earth in the garden, and a great many in the mouths and alimentary canals of people and of animals. Most of them are entirely harmless, and some, as we shall see, are really good friends of ours.
The Bacteria: The commonest kind of microbes are called bacteria. They are really very small plants; and if you were to look at them under the microscope, they would look something like the things you see in Figure 61. You never would think they were living plants, would you? They look like little sticks or balls, and are so small that 400,000,000 of them could be packed into a single grain of granulated sugar. Yet they are really alive. Some of them can move about, and under the microscope you can see them swimming along quite merrily.
When bacteria are living in something which they can feed upon, they grow larger and larger, till finally each one splits in half, and you have two microbes where there was only one before.
While they are doing this, they are destroying the sub-stance they are feeding on, and often they change its appearance and its smell and its taste, so as to "spoil" it, as we say. 'The decay of meat, the souring of milk, the molding of jellies and preserves, are all the result of the action of the bacteria or other microbes which are growing in them. If there were no microbes, food would not spoil at all. When your mother puts up preserves, she heats the jars and the preserves themselves, so as to kill all the microbes that may be there; and if the preserves do not keep, it is because some of the microbes were not killed or others got in after-ward.
Some Helpful Microbes.—Some kinds of microbes are really helpful to us. The taste of butter is the result of the action of bacteria growing in the cream from which the butter was made. The flavor of cheese is produced by other microbes. Vinegar is made from apple juice by the action of microbes. Above all, the microbes which live in the soil are very useful indeed in helping to make the soil rich and fertile so that plants can grow in it.
In far-northern Iceland, people used to believe that there were two sorts of elves or fairies. The White Elves were good fairies, who helped bake the bread and churn the butter, who found things that were lost, and sometimes swept the floor and tidied up a room that had been left in disorder overnight. The Bad Elves, on the other hand, were mischief makers, who hid and broke things about the house, pinched the cat's tail to frighten it when it was asleep, and led people astray at night in the marshes by showing false lights where there were no houses at all. The microbes are really somewhat like these invisible fairies. We cannot see them, but they are all about us. Some of them are our friends, like the ones that make cheese and work in the soil; some are our enemies, like those that spoil foods and those that cause disease.
Where the Disease Microbes Come From.—Most plants and animals have a special sort of place where they live, and we never find them anywhere else. Certain fishes live in the sea. Other kinds of fishes can live only in fresh-water lakes. Certain birds, like the sea-gulls, are found only near the ocean.. Certain kinds of insects live under stones or in old decaying logs, while others fly about in the sunny meadows. It is very much the same with the microbes. Some can live in earth, others in water; and the kinds that cause sickness generally live and thrive only in the human (or animal) body.
This is one of the great lessons that we have learned from the work of Pasteur: that the germs of disease dc not come from the air or the soil but from the bodies of people. We know now why diseases of the kind that are caused by microbes are "catching." When we say some one has "caught" cold, we mean that he has been near some one else who had a cold, and that the microbes that cause a cold have been passed from one person to the other. Measles, scarlet fever, whooping cough, diphtheria, typhoid fever, pneumonia, tuberculosis, and many more are diseases that are "catching" or contagious.
The person from whom you "catch" one of these diseases need not necessarily be ill himself. Sometimes if one is strong and well, the germs of a certain disease may get into his throat, for instance, and live there for a while without making him ill. Yet this person can pass on some of these germs to some one else who is not so strong, and the second person may fall sick as a result. Well people who have the germs of disease growing in their bodies in this way are called carriers, because they carry the microbes about with them.
Disease germs can live for a little while on things that have been handled by a sick person or a carrier—in food, for instance, or on handkerchiefs. Soon, how-ever; they will die, unless they get into the body of another human being, where they can begin to grow again. Now you can see how it is possible to prevent these diseases. Since every cold in the head, every case of measles, scarlet fever, or any other sickness of this kind, is caused by the passing on of germs from one person to another, we can stop the disease by pre-venting the spread of the germs.
How the Disease Microbes Pass from One Person to Another.—There are three principal ways by which the invisible germs are passed from one person to another; and if you understand these three ways, you can do a great deal to keep yourself and other people about you safe from their attacks.
First of all, the microbes may be passed from one person to another by direct contact or touching. Sup-pose your father has a cold and you kiss him. You will probably get the cold germs on your lips, and very soon you may come down with the cold, in your turn. When he coughs or sneezes, a fine spray of moisture is thrown out from his mouth, and in these drops of water there will be the germs which were growing in his mouth.
If he sneezes behind his hand and then touches your hand, and your hand goes to your mouth or nose, the germs will be passed on to you, in a more roundabout way but still by contact.
A second way in which disease germs often find their way from one person to another is by means of water or milk or some other food. If a man who is suffering from some germ disease coughs over a milk pail, the microbes from his mouth may be mixed up with a whole batch of milk at the dairy and may be carried to hundreds of people as a result.
Finally, the germs of some diseases are carried from one person to another by insects, such as flies and mosquitoes.
We sometimes speak of these three ways of spreading disease as the Three F's—Fingers, Food, and Flies—Fingers meaning all the various ways by which germs pass from one person to another by contact; Food, the spread of the germs by different foods; and Flies, the carrying of disease microbes by flies and other insects.