rs and walks erect because he
is drilled until his bones and joints grow in the proper shape. As you
stand straight with your feet together, your two big toes, your two
ankles, and your two knees should touch each other.

If you wear tight shoes and press the toes out of shape, they will
soon grow so. Nearly every one's feet are out of shape from wearing
short, pointed shoes. Your toes should be straight and not cramped by
the shoe. If you wear narrow shoes, you may harm your feet. It is
better to have one's feet useful, even if they are large, than to make
them small and useless.

WHAT WE HAVE LEARNED

1. Bones make the body stiff, and give it form.

2. Some bones are long, some round, and some flat. All are hard
and springy.

3. Some bones are hinged together. The hinge is a joint.

4. The ends of bones in joints are rounded and smooth, and are
oiled with a liquid like the white of an egg.

5. Some bones are bound together by springy pads, as in the
backbone.

6. Bones can be broken. They will grow together again themselves.

7. Joints can be put out of place; then we must put them back.

8. If joints or bones are kept in wrong positions they will grow
into bad shapes. Tight shoes deform the feet.

[Illustration: =The muscular system.=]

CHAPTER XV

MUSCLES

=187. Shape of muscles.=--Bones are covered with muscles. Muscles give
shape to the body, and move it about. One half of the body consists of
muscles. These are arranged in bundles, and each causes a bone to make
one motion. There are over four hundred separate bundles of muscle in
the body.

One end of a muscle is large and round and is fast to a bone. The
other end tapers to a strong string or tendon. The tendon passes over
a joint, and becomes fast to another bone. You can easily feel the
tendons in the wrist and behind the knee.

[Illustration: =Muscle cells, cut across (x200).=

_a_ muscle cell.
_b_ connective tissue binding the cells together.]

A muscle is made of tiny strings. You can pick them apart until they
are too fine to be seen with the eye. Each string is a living muscle
cell. It is the largest kind of cell in the body. You can see the fine
strings in cooked meat.

[Illustration: =A thin slice of a voluntary muscle, cut lengthwise
(x100).=

_a_ muscle cell.
_b_ capillaries surrounding the cells.
_c_ connective tissue bind