d blood, and their brain."

* * * * *

PART II.

FORMULA FOR THE PARTS AND JOINTS OF THE BODY:

1. My limbs are my two arms and my two legs.

2. My arm has two parts:

my upper arm, my fore-arm;

and three joints:

my shoulder joint, my elbow joint, my wrist joint.

3. My hand is used in holding, throwing, catching, and feeling:

the palm of my hand,
the back of my hand,
my fingers,
my thumb,
my forefinger,
my middle finger,
my ring finger,
my little finger,
my knuckles,
my finger joints,
my nails,
the tips of my fingers,
the veins,
the ball of my thumb,
and the lines where the flesh is bent.

4. My leg has two parts:

my thigh, and my lower leg;

and three joints:

my hip joint, my knee joint, my ankle joint.

5. My foot is used in standing, walking, running, skating, and jumping:

my instep,
my toes,
the sole of my foot,
the ball,
the hollow,
the heel,
my toe joints,
and my toe nails, which protect my toes.

* * * * *

QUESTIONS FOR THE FORMULA.

1. Which are your limbs?

2. Tell about your arm.

3. Tell about your hand.

4. Tell about your leg.

5. Tell about your foot.

* * * * *

[Illustration: THE ELBOW JOINT.
(A hinge joint.)]

[Illustration: THE HIP JOINT.
(A ball-and-socket joint.)]

Some joints, as those of the skull, are immovable; some, as those of the
spine, may be moved a little; and others more or less freely, as those of
the limbs. In machines, the parts which move upon each other need to be
oiled, to keep them from wearing out; but the joints of our bodies oil
themselves with a thin fluid, called _synovia_. This fluid resembles the
white of an egg, and comes from a smooth lining inside of the joints. The
ends of the bones which form joints are covered by gristle or _cartilage_,
and are fastened together by very strong, silvery white bands, called
_ligaments_. A sprain is caused by overstretching or tearing some of these
ligaments.

* * * * *

QUESTIONS ON THE LIMBS AND JOINTS OF THE BODY.

What is the trunk of your body?--"All the body but the head and limbs."

Which are your limbs?--"My two arms and my two legs."

How many limbs have you?--"Four."

How many parts has your arm?--"Two parts: my upper arm and my fore-arm."

How many