Then at last came relief; for in 1796 an Englishman, Dr. Jenner, learned how to save men by vaccination. Since that time smallpox has slipped into the background of the deadly diseases of the world. The explanation is that to-day in every civilized country vaccination has been adopted as a preventive. It is true that nowadays people feel so safe that they often grow careless. Even the mothers of the children sometimes forget to have their sons and daughters vaccinated. In such cases, however, the board of health of the city or town often steps in and gives commands. This was done by New York City in 1901. Without much warning smallpox had appeared in the place. People here and there who had not been vaccinated were down with the fever and were dying. Two hundred special inspectors were appointed at once, and within six months eight hundred and ten thousand citizens, young and old, had been vaccinated and the city was saved from what would have been an epidemic more frightful than that which swept over Ponape. For in a city human beings are crowded close together and microbes have a chance to spread fast.

While smallpox shows itself on the outside of the body, diphtheria takes its start within the throat. And here, also, we have a swift-moving disease which seems to fly from house to house through the power of an unseen hand. We ourselves know that in this case, too, the invisible power is a microbe which is able to kill its victim.

As happens also in any attack of diphtheria, life depends on the speed with which prevention can overtake the microbe as it multiplies. A child has a sore throat, then a fever. The doctor is called, and if he finds all the signs of the dread disease, he knows that his one hope is to kill the microbes before they can kill the child. Without a moment's delay, therefore, he uses the one great cure for diphtheria - antitoxin. He not only puts this into the body of the child who is ill, but also gives it to each person who has been anywhere near the child. Indeed, the disease itself passes so swiftly from one to another that the only safety is to use antitoxin on all alike. It not only helps cure the one who has the disease, but also protects those who have been exposed to it. In previous times about forty of every hundred who had diphtheria died of it. Now it kills not more than eight in each hundred. The difference in the death rate is explained by the power of antitoxin to save those who have been attacked by the microbe.

Last week the newspapers reported the sad case of three persons who had been bitten by a mad dog in a country town. The dog was owned by the president of a college in that town, and no one suspected danger until the dog had bitten one boy and two men. He was then caught and mercifully killed. And what of the men and the boy? The doctors in the place knew that there was hope of life for them if they could be treated with

an antitoxin which is prepared for just such cases. It destroys the power of hydrophobia microbes after they have been put into the body by the teeth of a mad dog. All three of the victims were therefore hurried to Chicago. There they were treated at a special hospital for such cases. One man had been a little slow in arriving and he alone suffered from the disease. The other man and the boy were rescued from it by the antitoxin which was given in time to save them from the microbes of hydrophobia. Perhaps no suffering is more dreadful and no death much sadder than that which comes through hydrophobia. In these days, however, even this disease is preventable. To save people from it, large cities in all parts of the civilized world prepare antitoxin and supply it to the doctors when needed.

In order to bring together the teachings of the last two chapters, they might be grouped as follows:

Avoid the public drinking cup and the public towel.

Do not rub your eyes with your fingers.

Do not touch your pencil to your lips.

Do not moisten fingers at the lips to turn a page.

Do not tolerate either flies or mosquitoes in your home. Do all you can to prevent them from multiplying in your town.

Adopt cleanliness of the home as your motto for life.

Vaccination prevents smallpox.

Antitoxin saves from diphtheria.

Antitoxin saves from hydrophobia.

Quarantine prevents the spread of measles and scarlet fever.

Thus we learn how certain diseases may be prevented. But, in addition to all else, let us never forget that the health of the body demands two great things of us:

1. That we destroy disease microbes (tubercle bacilli, typhoid microbes, etc.), before they have any chance to attack the body.

2. That we keep the defenses of the body in such vigorous condition that even if disease microbes enter, they will not conquer us but will be conquered by us.

In other words, our war against the microbe means that we do two things, and that we do them both at the same time:

1. Fortify the body.

2. Exterminate the foe.

CHAPTER XXXIII

STUDENTS, RAILROAD MEN, AND ALCOHOL

Several years ago Professor Kraepelin of Heidelberg University, Germany, did some experimenting in connection with the students of the place. He was just the one to carry on the experiments because he had already made a special study of the nervous system, and because in all parts of the world scientific men recognize the authority of his name. He himself says that he really wished to save a little of the reputation of wine and beer, for he saw that science was crowding pretty hard against every drink containing alcohol.

In experimenting with his students Professor Kraepelin always gave small doses. He knew, as we do, that those who use alcohol frequently in large doses ruin their lives hopelessly. Proofs of this are on every side, in every land. There are, however, thousands of honest people who heartily believe that alcohol taken in small doses is a help to them on all sorts of occasions. It was in this direction, therefore, that Professor Kraepelin experimented.

Various university students were eager to know facts, willing to be tested, and quite ready to drink or not to drink, according as the progress of the investigation