~11. Effects of Narcotics and Stimulants upon the Skin.~--Alcohol, tobacco, opium, and all other narcotics and stimulants have a bad effect upon the skin. Alcohol often causes the skin to become red and blotched, and tobacco gives it a dingy and unhealthy appearance. SUMMARY. 1. If the pores of the skin are closed, a person will die. 2. We should bathe often enough to keep the skin clean. 3. We should not keep our rooms too warm, and should avoid wearing too much clothing. 4. Alcohol, tobacco, and other stimulants and narcotics injure the skin. CHAPTER XVII. THE KIDNEYS AND THEIR WORK. ~1. The Kidneys.~--The kidneys are among the most important organs of the body. They are in the cavity of the abdomen, near the back-bone, up under the lower border of the ribs. Perhaps you have seen the kidneys of a sheep or a hog. If you have, you know very nearly how the kidneys of our own bodies appear. [Illustration: KIDNEY.] ~2. The Work of the Kidneys.~--The work of the kidneys is to separate from the blood certain very poisonous substances, which would soon cause our death if they were not removed. It is very important to keep these useful organs in good health, because a person is certain to die very soon when the kidneys are in any way seriously injured. ~3. How to Keep the Kidneys Healthy.~--One way of keeping the kidneys in good health is to drink plenty of pure water, and to avoid eating too much meat and rich food. Pepper, mustard, and other hot sauces are very harmful to the kidneys. ~4. Importance of Keeping the Skin Clean.~--The work of the kidneys is very similar to that of the skin; and when the skin does not do its full duty, the kidneys have to do more than they should, and hence are likely to become diseased. For this reason, persons who allow their skins to become inactive by neglecting to bathe frequently are apt to have disease of the kidneys. ~5. Effects of Alcohol and Tobacco upon the Kidneys.~--A piece of beef placed in alcohol soon becomes dry and hard, and shrivels up as though it had been burned. The effect upon the kidneys of drinking strong liquor is almost the same. Beer and hard cider also do the kidneys harm, sometimes producing incurable disease of these important organs. SUMMARY. 1. The kidneys somewhat resemble the skin in their structure and in their work. 2. The kidneys remove from the blood some poisonous substances. 3. To keep the kidneys healthy we should drink plenty of water, avoid irritating foods and drinks, and keep the skin in health by proper bathing. 4. The drinking of strong liquors often causes incurable disease of the kidneys. CHAPTER XVIII. OUR BONES AND THEIR USES. ~1. The Bones.~--In an earlier chapter we learned something about the bones. This we must try to recall. You will remember that we called the bones the framework of the body, just as the timbers which are first put up in building a house are called its frame.