To the invalid it is, of course, idle to talk of active exercise, but there are certain forms of passive exercise accessible to such people. Massage, for instance, which, judiciously administered, will do for the sick, in a modified degree, what active exercise does for the comparatively well. It will stimulate the circulation in the deeper tissues, and set the various fluids of the body moving in a beneficial manner. There is also a mild form of active exercise which may be practised by those who have the misfortune to be confined to bed, and that is by tensing the muscles; such as clenching the hands and contracting the toes, also by gentle contraction of the arms and legs alternately. But one of the most important factors in quickening and stimulating the movement of the fluids is exercising the lungs, and that can be accomplished with a fair measure of success even by the bed-ridden. Every time the chest cavity is emptied by the expiration of the breath a partial vacuum is created which exerts a tremendous suction power. It is one of the principal forces concerned in the return of the venous blood to the heart, but it also exerts a like effect upon the lymphatic current, hence deep breathing is a valuable exercise for those unable to take any other. In commencing the development of the body by any system of physical culture, the first and most important thing to do is to develop the lungs. Good lungs and good digestion go together. Before food can be assimilated it must undergo oxygenation, which is neither more nor less than chemical combustion. For this oxygen is necessary, which, uniting with the carbon of the food, results in oxidation, and as the amount of oxygen inhaled depends upon the capacity of the lungs, it will readily be seen how much depends upon those organs. We cannot inhale too much oxygen, while we can take too much food; therefore, the greater the lung capacity the better the digestion. We referred to the suction power of the empty chest cavity and its stimulating effect upon the fluids of the body. Now, the greater the lung capacity the greater the chest expansion and the vacuum produced by expiration; consequently the stimulating effect upon the fluids is correspondingly augmented. Test your lungs by inhaling a full breath--inflate them to their full capacity--if it makes you dizzy you are in danger and should proceed at once to strengthen them. The following simple exercises will speedily result in improvement and are easy to practice: HOW TO EXERCISE THE LUNGS. 1. When in the open air, walk erect, head up, chin drawn in, shoulders thrown back, thoroughly inflate the lungs and retain the air for a second or two, then expel it gently. Practice this several times a day, and if your employment keeps you in, make time and go out. [Illustration: FIG. 1.]