but flows steadily from a vein. If an artery is injured, the limb should
be tightly bandaged on the side of the wound nearest the heart; if a vein,
on the side farthest from the heart. In addition to this, the edges of the
wound should be closed and covered with cotton fiber and the limb should
be placed on a support above the level of the rest of the body. A large
handkerchief makes a convenient bandage if properly applied. This should
be folded diagonally and a knot tied in the middle. Opposite ends are then
tied, making a loose-fitting loop around the limb. The knot is placed
directly over the blood vessel to be compressed and a short stick inserted
in the loop. The necessary pressure is then applied by twisting the
handkerchief with the stick. Time must not be lost, however, in the
preparation of a suitable bandage. The blood vessel should be compressed
with the fingers while the bandage is being prepared.

*Summary.*—The blood, to serve as a transporting agent, must be kept
continually moving through all parts of the body. The blood vessels hold
the blood, supply the channels and force necessary for its circulation,
and provide conditions which enable materials both to enter and to leave
the blood stream. The heart is the chief factor in propelling the blood,
although the muscles and the elastic tissue in the walls of the arteries
and the valves in the veins are necessary aids in the process. In the
capillaries the blood takes on and gives off materials, while the arteries
and veins serve chiefly as tubes for conveying the blood from one system
of capillaries to another.

*Exercises.*—1. Of what special value in the study of the body was the
discovery of the circulation of the blood?

2. State the necessity for a circulating liquid in the body.