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."