Perspiratory tube.
The body is covered with skin. It is also lined with a more delicate kind of skin. You can see where the outside skin and the lining skin meet at your lips.
There is a thin outside layer of skin which we can pull off without hurting ourselves; but I advise you not to do so. Because under the outside skin is the true skin, which is so full of little nerves that it will feel the least touch as pain. When the outer skin, which protects it, is torn away, we must cover the true skin to keep it from harm.
In hot weather, or when any one has been working or playing hard, the face, and sometimes the whole body, is covered with little drops of water. We call these drops perspiration (pẽr spĭ rā´shŭn).
Where does it come from? It comes through many tiny holes in the skin, called pores (pōrz). Every pore is the mouth of a tiny tube which is carrying off waste matter and water from your body. If you could piece together all these little perspiration tubes that are in the skin of one person, they would make a line more than three miles long.
Sometimes, you can not see the perspiration, because there is not enough of it to form drops. But it is always coming out through your skin, both in winter and summer. Your body is kept healthy by having its worn-out matter carried off in this way, as well as in other ways.
THE NAILS.
The nails grow from the skin.
The finger nails are little shields to protect the ends of your fingers from getting hurt. These finger ends are full of tiny nerves, and would be badly off without such shields. No one likes to see nails that have been bitten.