alled the _trunk_.
At the top of the trunk is the _head_. The arms and legs are known as
_limbs_ or _extremities_. The part of the arm between the elbow and
wrist is the _forearm_. The _thigh_ is the part of the leg between the
knee and hip.

The upper part of the trunk is called the _chest_ and is encircled by
the ribs. The lower part of the trunk is named the _abdomen_. A large
cavity within the chest contains the lungs and heart. The cavity of
the abdomen is filled with the liver, stomach, food tube, and other
working parts.

=The Plan of the Body.=--All parts of the body are not the same. One
part has one kind of work to do while another performs quite a
different duty. The covering of the body is the _skin_. Beneath is the
red meat called _muscle_. It looks just like the beef bought at the
butcher shop which is the muscle of a cow or ox. Nearly one half of
the weight of the body is made of muscle.

[Illustration: FIG. 4.--General plan of the organs of the body.]

The muscle is fastened to the _bones_ which support the body and give
it stiffness. The muscle by pulling on the bones helps the body to do
all kinds of work. The muscles and bones cannot work day after day
without being fed. For this reason a food tube leads from the mouth
down into the trunk to prepare milk, meat, bread, or other food, for
the use of the body.

=Feeding the Body.=--The mouth receives the food and chews it so that it
may be easily swallowed. It then goes into a sac called the _stomach_.
Here the hard parts are broken up into tiny bits and float about in a
watery fluid. This goes out of the stomach into a long crooked tube, the
_intestine_. Here the particles are made still finer, and the whole mass
is then ready to be carried to every part of the muscles, bones, and
brain to build up what is being worn out in work and play.

=Carrying Food through the Body.=--In all parts of the body are little
branching tubes. These unite into larger tubes leading to the heart.
Through these tubes flows _blood_. Hundreds of tiny tubes in the walls
of the intestine drink in the watery food, and it flows with the blood
to the heart. The heart then pushes this blood with its food out
through another set of tubes which divide into fine branches as they
lead to every part of the body (Fig. 5).

=Getting rid of Ashes and Worn-out Parts.=--The body works like a
machine. Food is used somewhat as a locomotive uses coal to give it
power to work. Some ashe