the left how biting off the nails
makes the fingers blunt and sore.]

Many boys and some girls spoil the appearance of their nails by
letting a line of black dirt remain beneath them. A piece of a stick
or a nail cleaner should be passed beneath the nails every time the
hands are washed. If the fingers are much soiled, a stiff brush is
useful in removing the dirt under the nails.

[Illustration: FIG. 47.--A slice through a hair in its sac. Much
enlarged.]

=The Hair.=--Some hair grows on nearly all parts of the body. It is
much thicker on the head than elsewhere. Each hair grows from a
little knob at the bottom of a tiny tube in the skin called the _hair
sac_ (Fig. 47). If hair is pulled out, another one will grow in its
place if the knob at the bottom of the sac is not hurt.

One or two _oil glands_ open into each hair sac and give out an oil to
keep the scalp and hair soft. No other hair dressing is needed.

After thirty or forty years of age the hair begins to turn gray. No
medicine will prevent the hair from turning gray, and it is generally
unwise to color the hair with a dye. There is poison in some of the
mixtures sold to color the hair.

=The Care of the Hair.=--When the hair is uncombed, the whole person
looks untidy. The hair should be combed carefully every morning and
again made tidy before each meal. You should use as little water as
possible to moisten the hair. The glands can be made to give out their
hair oil by squeezing parts of the scalp between the fingers.

The scalp should be well cleansed with soap and warm water every three
or four weeks. The hair should be dried quickly with a soft towel and
by sitting in the sun or near a stove. One is likely to catch cold by
going out of doors when the hair is wet. Hair oils and dandruff cures
should not be used unless advised by a physician. Pinching and wrinkling
the scalp twice weekly with the fingers makes the blood tubes grow
larger and bring more food to the hair. It will also in many persons
stop the hair from falling out and prevent dandruff and itching.

[Illustration: FIG. 48.--Photographs showing how keeping the hair tidy
improves the appearance.]

Do not use the hair brush of another person or exchange hats with your
companions. Unclean persons and those living or playing much with them
often have among their hairs little creatures called _head lice_. They
suck blood and cause constant itching. The doctor will tell any one
how to get ri