e and
the chin."

Of what use is the mouth?--"To breathe, speak, and eat through."

What is in the mouth?--"My tongue, my upper teeth, my lower teeth, and my
upper and lower jaws."

What covers the jaws?--"Red flesh, called _gum_."

Of what are the jaws composed?--"Of bones."

Of what are the teeth made?--"Of dentine, covered with enamel." See note,
p. 19.

What is enamel?--"A smooth, white substance, harder than bone."

Of what use are the teeth?--"To eat and talk with."

What kinds of teeth have you?--"Cutting teeth, tearing teeth, grinding
teeth."

Describe the cutting teeth.--"The cutting teeth have broad and flat edges."

Describe the tearing teeth.--"The tearing teeth are sharp and pointed."

Describe the grinding teeth.--"The grinding teeth are the thick, back
teeth."

Which jaw is moved in eating?--"The lower jaw."

What work do the teeth perform?--"They cut, tear, and grind the food."

How many teeth has a child in a full set?--"Twenty teeth: ten in each jaw."

How many teeth has a grown person in a full set?--"Thirty-two: sixteen in
each jaw."

What does the tongue do in eating?--"It rolls the food between the teeth,
and helps in swallowing."

What is the saliva?--"A kind of liquid, sometimes called _spit_."

Of what use is it in eating?--"It wets and softens the food."

What do you mean by preserve?--"To keep from injury."

What do you mean by injury?--"Hurt."

How do you preserve your teeth? See Formula.

How do very hot or very cold drinks hurt the teeth?--"They crack the
enamel."

What happens if the enamel is cracked?--"The teeth decay."

Then what must you do to preserve your teeth?--"I must try to keep the
enamel from being cracked or injured in any way."

* * * * *

PART V.

FORMULA FOR DESCRIPTION OF THE BONES.

1. My skull is formed of several bones united, like two saws with their
toothed edges hooked into each other.

2. My spine extends from the base of the skull behind, down the middle of
my back.

It is composed of twenty-four short bones, piled one upon the other, with
cartilage between them.

These bones are fastened together, forming an upright and flexible column,
which makes me erect and graceful.

3. My ribs are curved, strong, and light; there are twenty-four of them,
twelve on each side; they are fastened at the back to my spine, in front to
my breastbone, forming a hollow place for my heart, lungs, and stomach.