The curves of the spinal column are of great value in protecting the brain, as they weaken the force of any shock, which may be caused by striking the bones of the feet. =Common Defects in the Carriage of the Body.=—Owing to the common faulty position of school children at their desks, the sedentary occupations of women, and their lack of physical training, curvature of the spine is very common. A stooping carriage is the most common. The head is bent forward, the chest is sunken, the back is round, the shoulder-blades hang outward, the inner edges standing out like wings, and the abdomen is protuberant. The muscles are poorly developed and are weak and flabby. This stooping carriage interferes with the freedom in breathing, and prevents the proper development of the upper part of the chest and lungs. Hence, it predisposes to lung diseases and tuberculosis, a weak heart, poor circulation, shortness of breath, inability to take proper exercise, and thinness of the blood (anemia). _Spinal Curvatures._—The spinal column is normally directly in the middle of the back; any deviation of this column to either side is abnormal, and the lungs become cramped in a small and non-distensible bony cage. This spinal curvature is most apt to take place in young girls or in adult women after a severe illness, when the muscles of the back have become particularly flabby, and, while still in this condition, improper attitudes are assumed at the desk or other sedentary occupations. Preventive measures are of the utmost importance. First of all, comes the general strengthening of the body, and of the muscles and bones in particular, by plenty of exercise in the open air. The habitual attitude at the desk and work should always be carefully observed, and in all sedentary occupations the work should be frequently interrupted to take systematic breathing exercises before an open window. Where spinal curvature has actually taken place, especial exercises must be taken under the supervision of a physician and instructor. Gymnastic exercises must be supplemented by outdoor games and sports. =The Heart’s Need of Exercise.=—The first essential for the maintenance of health, capacity for work, and power of resistance of disease is a normally developed and strong heart. First, there must be secured a vigorous circulation of the blood, and the two greatest helps to this are exercise and deep breathing. In the sedentary posture the heart works at a disadvantage. For the young, exercise of the heart is the chief object of physical exercises; this object is best attained by exercises of speed, especially in the form of games which require rapid movement. In youth the recuperative powers of the heart and lungs are at the highest.