We do not know just how tobacco affects the cells of the nervous system. It may be that they are affected mostly by being deprived of oxygen, or it may be that the tobacco affects them directly. However the harm is done, we know that the cells of the nervous system are affected by tobacco. One of the nerves that is most commonly affected by the use of tobacco is the nerve of the eye, the nerve that enables us to see. We know that when people use tobacco a great deal they sometimes lose their sight. This does not happen to everyone who uses tobacco, but you can never tell whom it will affect in this way. The only safe thing to do is not to use tobacco, and then you will know that you will not lose your sight from this cause. [Sidenote: (_4_) On the stomach] The use of tobacco affects the stomach. People who use tobacco a great deal are likely to have indigestion. The tobacco causes this probably by depriving the stomach cells of oxygen through its effect on the blood cells. [Sidenote: (_5_) On the heart] Tobacco has a very bad effect on the heart. People who use much tobacco have what they call "palpitation of the heart," but doctors call it "tobacco heart," because it is caused by the use of tobacco. No insurance company will insure a person who has "tobacco heart." Most boys grow up to be men before they manage to use enough tobacco to cause tobacco heart. However, long before they are grown, they show that the tobacco has affected their hearts, because they are short of breath and stand about as much chance of winning a race as does a mouth-breather. [Sidenote: Effects of alcohol:] The effect of alcohol is a subject on which I want to speak very plainly and frankly, because I do not want the boys and girls who read this to get the same idea that I got when I was in school, or to be affected by it as I was. When I was a little boy I was taught that if a person drank alcohol in any form the lining of his stomach would be eaten up. In proof of this statement I was shown a picture of an ulcerated stomach that was said to have resulted from drinking whisky. Naturally I expected to find that people who drank whisky would not be able to eat anything at all, or would be troubled a great deal with pain in their stomachs. To my surprise, I found that many people had ulcers of the stomach who never took an alcoholic drink, while many of those who drank a great deal seemed to have the best of appetites and were never troubled with their stomachs. As a result, I came to the conclusion that all this talk about the evil effects of alcohol was foolishness. Later I studied medicine, and learned that the effect of alcohol on the stomach is, in reality, the least of its evils. But I want to impress upon you that, as a result of forty years' study, I consider alcohol the most dangerous thing in the world to-day. By "alcohol" we mean any drink that contains alcohol, such as whisky, wine, brandy, beer, etc. [Sidenote: (_1_) On the stomach]