*Checking of Flow of Blood from Wounds.*—The loss of any considerable quantity of blood is such a serious matter that every one should know the simpler methods of checking its flow from wounds. In small wounds the flow is easily checked by binding cotton or linen fiber over the place. The absorbent cotton, sold in small packages at drug stores, is excellent for this purpose and should be kept in every home. A simple method of checking "nosebleed" is that of drawing air through the bleeding nostril, while the other nostril is compressed with the finger.(24) Another method is to "press with the finger (or insert a small roll of paper) under the lip against the base of the nose." (25) Where the bleeding is persistent, the nostril should be plugged with a small roll of clean cotton or paper. When this is done, the plug should not be removed too soon because of the likelihood of starting the flow afresh. In dealing with large wounds the services of a physician are indispensable. But in waiting for the physician to arrive temporary aid must be rendered. The one who gives such aid should first decide whether an artery or a vein has been injured. This is easily determined by the nature of the blood stream, which is in jets, or spurts, from an artery, 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?