=The Sense of Taste.=--The nerves by which we taste end in the soft covering of the tongue and some other parts of the mouth. A food cannot be tasted while it is dry. For this reason much slippery fluid flows into the mouth from glands under the ears and tongue. This fluid, called _saliva_, softens the solid food when it is well chewed, so we can taste it. =The Senses of the Skin.=--There are endings of nerves in the skin all over the body. They are of three or four different kinds. Some of them tell us about heat, others tell us about cold. Some tell us about the shape, the smoothness, or hardness of objects, while others tell us when the skin gets hurt. Most of the nerve endings are in the deeper part of the skin, so that they are covered by the epidermis and cannot be hurt by the rough things handled. =Alcohol and the Senses.=--The senses are but little affected by a small amount of alcoholic drink. The sense of taste, after being accustomed to the sharpness of strong drink, may be less easily pleased with the taste of common food and drink. The use of large amounts of alcohol blunts all the senses. In a drunken man the senses of the skin are so numbed that he does not know when anything touches him, and he may be badly burned before he feels the pain. Heavy drinking makes the hearing less keen, enlarges the blood vessels of the eyes, and makes them appear red and bloodshot. =Tobacco and the Senses.=--The use of tobacco does not injure the senses of the skin and usually has no effect on hearing. Both chewing and smoking, if much practiced, make the sense of taste less delicate, so that one cannot enjoy his food to the fullest extent. Much smoking of tobacco may hurt the nerve of sight and in a few cases it has made men blind. Many boys have weakened their eyes by the use of cigarettes. PRACTICAL QUESTIONS 1. Name the chief sense organs. 2. Of what use are the eyelids and tears? 3. Name four parts of the eyeball. 4. What is the iris? 5. Of what use is the lens? 6. What moves the eyeball? 7. When do children get weak eyes? 8. How are the eyes often hurt? 9. How may poor eyes be helped? 10. What makes the eyes sore? 11. How do germs get into the eyes? 12. Name the three parts of the ear. 13. What does the inner ear contain? 14. What may result from neglecting a sick ear? 15. Of what use is smell? 16. Why should food be well chewed? 17. In what part of the skin are most of the nerve endings? 18. What effect does tobacco have on the sense of taste? CHAPTER XXIII KEEPING AWAY SICKNESS