THE HEART-PUMP AND ITS PIPE-LINE SYSTEM THE BLOOD VESSELS Where the Body Does its Real Eating.

When once the food has been dissolved in the food-tube and absorbed by the cells of its walls, the next problem is how it shall be sent all over the body to supply the different parts that are hungry for it; for we must remember that the real eating of the food is done by the billions upon billions of tiny living cells of which the body is made up.
The Pipe Lines of the Body.

What do we do when we want to carry water, or oil, or sewage, quickly and surely from one place to another?
We put down a pipe line.

We are wonderfully proud of our systems of water and gas supply, and of the great pipe lines that carry oil from wells in Ohio and Indiana clear to the Atlantic coast.

But the very first man that ever laid a pipe to carry water was simply imitating nature--only about ten or fifteen million years behind her.