9. The eye is moistened by tears from the tear-gland.
10. When we look at an object the lens of the eye makes a picture on the nerve of sight, at the back part of the eyeball.
11. To keep the eyes healthy we should be careful not to tax them long at a time with fine work, or to use them in a poor light.
12. The nerves of smell are placed in the upper part of the inside of the nose.
13. "Colds" often destroy the sense of smell.
14. The nerves of taste are placed in the tongue and palate.
15. Many things which we think we taste we really do not taste, but smell or feel.
16. Objects which have a pleasant taste are usually healthful, while those which have a bad taste are usually harmful.
17. Pepper, mustard, etc., as well as alcohol and tobacco, have an unpleasant taste, and are not healthful. If we use them we shall injure the nerves of taste as well as other parts of the body.
18. We feel objects by means of the sense of touch.