AND THINK.

~1. How we Think.~--With what part of the body do we think? You will at
once say that we think with the head; but we do not think with the whole
head. Some parts of the head we use for other purposes, as the mouth to
eat and speak with, and the nose to smell and breathe with. The part we
think with is inside of the skull, safely placed in a little room at the
top and back part of the head. Do you remember the name of this organ
which fills the hollow place inside of the skull? We learned some time
ago that it is called the _brain_. It is with the brain that we study
and remember and reason. So the brain is one of the most important
organs in our body, and we must try to learn all we can about it.

~2. The Brain.~--You cannot see and examine your own brain because it is
shut up in the skull; but perhaps you can find the brain of a sheep or a
calf at the meat market. The brain of one of these animals looks very
nearly like your own.

~3. The Large Brain and the Small Brain.~--In examining a brain we
should notice first of all that there are really two brains, a _large
brain_ and a _small brain_. The large brain is in the top and front of
the skull, and the small one lies beneath the back part of the larger
one, If we look again we shall see that each brain is divided in the
middle into a right and a left half. Each half is, in fact, a complete
brain, so that we really have two pairs of brains.

[Illustration: THE BRAIN.]

~4. Brain Cells.~--The brain is a curious organ of a grayish color
outside and white inside. It is soft, almost like jelly, and this is why
it is placed so carefully in a strong, bony box. If we should put a
little piece of the brain under a microscope, we should find that it is
made up of a great number of very small objects called _nerve_ or
_brain cells_. In the illustration you can see some of these brain
cells.

[Illustration: BRAIN CELLS.]

~5. The Nerves.~--Each cell has one or more branches. Some of the
branches are joined to the branches of other cells so as to unite the
cells together, just as children take hold of one another's hands. Other
branches are drawn out very long.

~6.~ The long branches are such slender threads that a great number of
them together would not be as large as a fine silk thread. A great many
of these fine nerve threads are bound up in little bundles which look
like white cords. These are called _nerves_.

~7.~ The nerves branch out from the brai