on the heart."

How does exercise help the free circulation of the blood?--"Exercise makes
the heart beat faster, which causes the blood to more faster through the
arteries and veins."

Why does keeping the body warm help the circulation of the blood?--"Because
the blood moves faster when it is warmest; cold chills the blood, and makes
it move slowly."

What harm do alcoholic liquors do to the heart?--"They make it tired, and
sometimes wear it out."

In what way do they make it tired?--"They make it beat too fast."

Why does it beat too fast?--"Because it is hurrying to drive the alcohol
out of the body."

In what other way do alcoholic liquors hurt the heart?--"They produce
disease in it."

Tell one way by which the heart becomes diseased through alcoholic
liquors?--"Alcohol softens the fibres of the muscles of the heart, and
fills them with fat."

What harm does this do to the heart?--"It makes it too weak to do its work,
which is to pump the blood through the body."

What sometimes happens when the heart is thus weakened?--"It stops beating,
which causes sudden death."

What harm does alcohol do to the blood?--"It uses up the water of the
blood; it destroys the goodness of the red part; it makes the blood thin,
impure, and unfit to do its work." See Appendices on Alcohol and Tobacco.

* * * * *

[Illustration: THE LUNGS.]

1, 2, the larynx, the upper part of the windpipe.
3, the windpipe, or trachea.
4, where the windpipe divides to right and left lungs.
5, the right bronchial tube.
6, the left bronchial tube.
7, outline of the right lung.
8, outline of the left lung.
9, the left lung.
10, the right lung.

* * * * *

PART IX.

FORMULA FOR THE LESSON ON THE LUNGS AND RESPIRATION.

1. My lungs are the bellows or breathing machines of my body.

2. They are composed of a soft, fleshy substance, full of small air-cells
and tubes. They are porous and spongy when healthy, but in some diseases
become an almost solid mass, through which the air cannot pass.

3. I breathe by drawing the air through my windpipe, along the tubes into
the cells of my lungs, swelling them out, and causing my chest to expand;
then the chest contracts, and the impure vapor in my lungs is pressed out
through the same tubes, windpipe, nose, and mouth, into the atmosphere.

4. I cannot live without breathing, because if the air does not go down