The custom of going barefoot is a dangerous one. The sole of the foot is a very delicate surface; a great many nerves and blood vessels center in the instep, and any injury to these may produce the disease called _lockjaw_, which usually results fatally. Even if nothing so serious as this happens, the foot is often injured by bruising or by other hurts. The feet are susceptible to chill, especially in the rainy season, when they should be kept dry and warm. Disease is often taken through the feet, especially such diseases as the bubonic plague, and the different kinds of itch which are known in the tropics. Aside from all these reasons why we should dress the feet, it is an untidy practice to go barefoot. The low shoes without fastenings, into which so many Filipinos thrust their feet, give people who wear them an awkward, shuffling walk. A shoe which fits the foot well and is fastened upon it so that it does not flap at the heel is the only one that should be worn out-of-doors, and no shoes should be worn without stockings. Every boy or girl who wants to be well must take exercise. If we do not use our muscles, they become weak and small. The brain suffers as well. When we exercise we not only strengthen our muscles, but we set the blood in quicker circulation. The heart must work faster; the lungs must expand more; the food digests better and the brain is clearer. The best sort of exercise is useful work out-of-doors or about the house, but boys and girls need to play as well as work. All games that take them out-of-doors and make them move about actively are good for them. Many Filipino boys and girls do one thing that is very hurtful; that is, they smoke. The use of tobacco injures growing young people. It stunts the growth, so that even when grown they are small and weak. Boys who smoke do not grow so fast or so large as those who do not. Smoking injures the memory and makes people heavy and stupid; it makes them less inclined to take exercise, and so the muscles become weak; it hurts the digestion and makes the stomach weak. Besides these things, it induces the constant spitting so common in this country; and we have seen how hurtful this waste of the saliva is. Chewing betel nut is even worse than smoking. If all of the betel juice is not spit out, some of it will be swallowed, and this is very bad indeed, as the betel acts like a poison on the system. So the betel chewer must waste all the saliva that comes into his mouth while he is chewing the nut. More than this, he stains the sidewalks and floors with the filthy stuff, and makes himself ugly to look at, as well as offensive to cleanliness. It is to be hoped that the boys and girls who study this book will never take up such a disgusting habit. Still another thing which is very bad for the health in this country is the use of alcohol. Alcohol is bad for the system; it irritates the delicate lining of the food canal, and hurts the liver and the kidneys.