“Runners always have large and active chests, whereas sedentary persons have chests of limited capacity and rigid walls. When a chest is not stretched to its utmost capacity many times daily, it rapidly loses its flexibility. This is especially true after the age of thirty. In persons who have passed middle life, the rigidity of the chest is so great that there can be no very considerable increase in size. By development of the respiratory muscles the chest capacity may be to some degree increased, but the proper time for chest development is in childhood and youth. At this period, also, the integrity of the heart renders possible without injury those vigorous exercises which are essential to secure the highest degree of chest development. “Probably the best of all exercises for the development of the chest and breathing powers is swimming. The position of the body, the head held well back and the chest well forward, and the active movements of the arms and limbs render swimming a most efficient breathing exercise. The contact of cold water with the skin also actively stimulates the movement of the chest, while at the same time it renders possible prolonged and vigorous muscular movements by increasing the energy and activity of the muscles. “Special breathing exercises, as well as those active muscular movements which induce a thirst for air, are beneficial to the lungs by maintaining the flexibility of the chest, strengthening the respiratory muscles, and ventilating the lungs. These movements also exercise a most extraordinary beneficial effect upon the stomach, liver, and other organs which lie below the diaphragm. Each time the diaphragm contracts, it gives the liver, stomach, and adjacent organs a hearty squeeze, so to speak, emptying out the blood contained in these parts as one may by compression empty a moist sponge. All movements which increase the strength of the abdominal muscles are an important means of aiding and improving the breathing function.” From this it will be seen, therefore, that everything that prevents the full and free exercise of the lungs, especially in the lower portions, is of direct injury to the body. Men need all the lung capacity and power they can gain in order to sustain their energy in the battle of life; and women, especially young women, who are to become the future mothers of the race, should be taught that the art of healthy, deep breathing is one of the fine arts, and the most important one that they can learn. [Illustration: NAVAHO BLANKET WEAVER IN HER OPEN AIR WORK-SHOP.] CHAPTER IV THE INDIAN AND OUT-OF-DOOR LIFE