ing 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

=Too Much Sickness.=--Many diseases are caused by our own carelessness
and our bad habits of living. We have about one doctor for every one
hundred families. There are enough people sick every day to make a
city as large as New York or to equal the number of people living in
the thirteen states of Idaho, Nevada, Wyoming, Arizona, New Mexico,
Utah, Delaware, Montana, Vermont, New Hampshire, North Dakota and
South Dakota, and Oklahoma.

A careful study of disease and its cause shows that at least one half
of all the sickness in our land can be avoided by right living.

=The Cause of Sickness.=--Some people are so foolish as to make
themselves sick. They weaken the body by using much beer or wine, by
breathing bad air, by lack of exercise, or by fast eating. When the
body becomes weak, it is likely to get sick at any time.

[Illustration: FIG. 93.--The germs of diseases. Much enlarged.]

It is not always our own fault when we are sick. It may be caused by
the carelessness of others who have let germs escape from their bodies
so that they are able to reach us. One half of the