TION OF THE BONES.

Point to the skull.

Of what is it made?--"Several bones united together."

How are the skull bones united?--"Like two saws with their toothed edges
hooked into each other."

What do you mean by _toothed_?--"Having points, like teeth."

What covers the skull?--"Flesh, skin, and hair."

Of what use is the skull?--"It protects the brain."

What is the brain?--"That part of my body in which the thinking is done."

Where is the spine?--"It extends from the base of my skull behind, down the
middle of my back."

What do you mean by _extends_?--"Goes from."

What do you mean by _base_?--"The lower part of anything."

Of what is the spine made?--"Of about twenty-four short bones, with
cartilage between them."

What is cartilage?--"An elastic substance, harder than flesh, but softer
than bone."

How are the bones of the spine placed?--"They are piled one upon the
other."

What do you mean by _forming_?--"Making."

What do you mean by _upright_?--"In a vertical position."

What do you mean by _flexible_?--"Easily bent."

What do you mean by _column_?--"A pillar."

What do you mean by _erect_?--"In a vertical position."

Why is cartilage placed between the bones of the spine?--"To make the spine
flexible; to keep the brain from injury when we walk or run."

What do you mean by _elastic_?--"Springing back after having been
stretched, squeezed, twisted, or bent."

Tell about your ribs.--"My ribs are curved, strong, and light."

Where are your ribs?--"On each side of my trunk."

How many ribs have you?--"Twenty-four; twelve on each side."

How are your ribs fastened?--"At the back to my spine; in front to my
breastbone."

What do your ribs form?--"A hollow place for my heart, lungs, and stomach."

Where are your shoulder blades?--"In the upper part of my back."

What shape are they?--"Flat, thin, and like a triangle."

Of what use are your shoulder blades?--"For my arms to rest upon."

Point to your collar bones.

Where are they fastened?--"To my shoulder blades and my breastbone."

Of what use are your collar bones?--"They keep my arms from sliding too far
forward."

Of what are your bones made?--"Of food after it has been changed into
blood."

Why should you eat wholesome food?--"That my bones may be strong and
healthy."

How does impure air hurt the bones?--"Impure air makes bad blood, and bad
blood makes poor bones."

Why should you sit and stand erect?--"Because my