you
should take a good hot bath with soap and then sponge down in cool
water. See how the birds enjoy their bath; and you will, too, if you
once get into the habit of bathing regularly.

Now let us take a good look at this coat and see if we can find out
what it is like.

The other day I saw some boys playing basketball. They wore short
sleeves and short trousers. Four were Indians, and five were white
boys, and one was a negro. The skin of the white boys seemed to shine,
it looked so white; and the negro's shone in its blackness; but the
Indian's looked a dull rich dusky brown.

Yes, you say, they belong to different races.

But what causes the difference in their color?

Little specks of coloring matter, or _pigment_, which lie in the outer
layer of the skin. Even white skins contain a little pigment, they are
not a pure white. A Chinaman's skin has a little more of this pigment,
so that it looks yellow; an Indian's has still more; and a negro's has
most of all, making him black.

Sunlight can increase the amount of pigment in the skin. The people
who live in the torrid zone have much darker skins than those who live
where the days are short and cold. You have noticed, yourself, that
when you expose the skin of your face or arms to the hot sun, you
become freckled, or tanned. This tanning, or browning, of the outer
layer of the skin protects the more delicate coats of skin below from
being scorched or injured by the strong light.

When you are playing and running with your schoolmates, you see that
their faces grow very red, and even their hands. Why is this? Because
the heart has been pumping hard and has sent the red blood out toward
the skin. The red color shines through the outer part of the skin. The
pigment in the Indian's skin, or the negro's, prevents the red blood
underneath from shining through, as it does through yours.

[Illustration: THE PARTS OF THE SKIN

The pore P on the surface of the skin is the end of a tube
through which sweat flows out. At O are the oil sacs that feed
the hair H. At B are the little blood vessels that make the skin
look pink.]

The skin, you see, is made up of different layers. When you burn
yourself, you can see a layer of skin stand out like a blister. It is
white; but if the blister is broken, underneath you see the coat that
is full of tiny blood vessels, so tiny and so close together that this
whole coat looks red. The skin, like every other p