Part 10 (2/2)

How should the muscles be used?--”They should be exercised in work or play.”

How may they be rested?--”I may rest my muscles by changing position; by changing my kind of work or play; or by going to sleep.”

Explain what you mean by changing your position.--”If I am standing, I must sit or lie down to rest them; if they are tired, because I have been sitting too long, I must rest them by standing, walking, or running.”

What do you mean by changing the kind of work or play?--”If, in my work or play, my arms become tired, I must do something in which my arms may rest, though other parts of my body may be in exercise.”

How may you help supply your muscles with good blood?--”By breathing pure air; by taking wholesome food and drink; and by living in the sunlight.”

How does drinking alcoholic liquors hurt the muscles?--”It makes them weak, and unfit to move the parts of the body.”

What wonderful muscle moves without your will?--”The heart.”

How does alcohol hurt the heart?--”It makes it beat too fast.”

How does ”beating too fast” hurt the heart?--”It makes it tired, and sometimes wears it out.” See Appendices on Alcohol and Tobacco.

[Ill.u.s.tration: THE SKIN (very highly magnified).--(From Walker's _Physiology_, 1884.)]

A, arteries; V, veins; N, nerves; F, fat cells; E, the outer skin; CL, the color layer; D, the true skin; PT, a perspiratory tube; HF, a hair and hair sac; EP, muscles; SG, oil glands; TC, tactile corpuscles; CT, connective tissue.

PART VII.

FORMULA FOR THE LESSON ON THE SKIN.

1. My skin covers my body.

2. It is thin, elastic, flexible, porous, and absorbent.

3. I have two skins; the inner skin is the true skin.

4. My true skin is elastic, and like a net-work of blood-vessels and nerves. My true skin is covered with a jelly-like substance which gives color to my skin.

5. My outside skin is not the same thickness over my whole body. In some parts, as on the palms of my hands and the soles of my feet, it is very thick and tough.

6. If my outside skin be destroyed, it will grow again; if the jelly-like substance be destroyed, it will re-appear; but if my true skin be destroyed, it will never be perfectly renewed.

7. More than half of the waste substance of my body pa.s.ses from it through the pores of the skin, in the form of perspiration.

8. If I would have a healthy skin, I must perspire freely all the time, I must keep my body clean, I must wear clean clothing, I must breathe pure air, and live in the sunlight.

QUESTIONS FOR THE FORMULA.

<script>