A grown person has thirty-two teeth, sixteen in each jaw.

6. To preserve my teeth:

I must keep them clean.

I must not scratch the enamel.

I must not eat or drink anything very hot or very cold.

I must not use them for scissors or nut-crackers.

I must not burn them with tobacco or cigars.

7. _About Eating._--When I eat I move my lower jaw only.

My tongue brings the food between my teeth, the cutters cut it, the tearers tear it, the grinders grind it, the saliva moistens it, and my tongue helps me to swallow it.

QUESTIONS FOR THE FORMULAS.

1. Tell about your eyes.

2. Tell about your ears.

3. Tell about your nose.

4. Tell about your mouth.

5. Tell about your teeth.

6. What is necessary if you would preserve your teeth?

7. Tell about eating.

[Ill.u.s.tration

1, the muscle which raises the upper eyelid.

2, the upper oblique muscle.

7, the lower oblique muscle. The oblique muscles roll the eye inward and downward.

4, 5, 6, three of the _four_ straight muscles. Two of the straight muscles roll the eye up and down; the other two move it right and left.

3, the pulley through which the upper oblique muscle plays.]

QUESTIONS ON THE DESCRIPTION OF THE EYES.

Of what shape is the eye?--"It is round like a ball."

In what is it placed?--"In a deep, bony socket."

What is a socket?--"A hollow place."

Why is the eye placed in a deep, bony socket?--"To keep it from getting hurt."

Why would not an eye shaped like a cube do for us?--"It would not look well; it could not be rolled about."

Why would not an eye shaped like a cone or cylinder do for us?--"It could not be rolled in every direction."

Why is the ball-shape best for the eye?--"It looks best, and may be rolled in every direction."

What part of the eye do we see through?--"The black spot in the centre."

What is it called?--"The pupil."

What shape is the pupil?--"Round like a circle."

What color is the pupil?--"Black."

Of what use is the pupil?--"To let light into the eye; to see through."

What is around the pupil?--"A colored ring."

What is the colored ring called?--"The iris."

Of what use is the iris?--"It acts like a curtain to the eye; it lets in and keeps out light from the pupil."

Of what shape is the iris?--"Round like a ring."

Of what color is the iris?--"Sometimes blue, sometimes brown, sometimes gray."

Does the iris always appear the same in size?--"It does not: sometimes it looks large, sometimes small."

When is it the largest?--"When it rolls over the pupil to keep out the strong light."

When is it the smallest?--"When it rolls backward, to let light into the pupil."

When is the pupil the largest?--"When we are in the dark."

When is the pupil the smallest?--"When we are in a bright light."

What color is the eyeball?--"White."

What shape is the eyeball?--"Round like a ball."

How is the eyeball held in its socket?--"By cords made of flesh."

Where are the eyebrows?--"Above the eyelids."

Of what use are the eyebrows?--"To keep the perspiration from rolling into the eyes."