The Eyeball.~--Looking at the eye, we see first a round part which rolls in different directions.

This is the _eyeball_.

We see only the front side of the eyeball as it fits into a hollow in the skull.

Being thus in a safe place, it is not likely to get hurt.
[Illustration: THE EYE.] The eyeball is mostly filled with a clear substance very much like jelly.

It is so clear that the light can shine through it just as easily as it can shine through water.
~10.