It will be found very pleasurable and invigorating to take a cold shower or spray off and on during the sun bath and to allow the air to dry the body. This will also increase its electromagnetic effects upon the system. The Friction Bath While taking the air bath, the skin may be rubbed or brushed with a rough towel or a flesh brush in order to remove the excretions and the atrophied cuticle. The friction bath should always be followed by a spray or a cold-water rub. At the time of the air bath, practice breathing exercises and the curative gymnastics appropriate to your condition. (See Chapters Twenty-Eight and Thirty on "Correct Breathing" and "Physical Exercise.") If the air bath is taken at night, before retiring, the less active breathing exercises, as numbers 1, 3, 7 and 13, may be taken with good results, but all vigorous stimulating movements should be avoided. As the plant prospers under the life-giving influence of water and light, so the cuticle of the human skin becomes alive and active under the natural stimulation of water, air and sunlight. From the foregoing paragraphs it will be seen why the air and light baths are regarded among the most important natural methods of treatment in all the great Nature Cure sanitariums of Germany. Chapter XXX Correct Breathing The lungs are to the body what the bellows are to the fires of the forge. The more regularly and vigorously the air is forced through the bellows and through the lungs, the livelier burns the flame in the smithy and the fires of life in the body. Practice deep, regular breathing systematically for one week, and you will be surprised at the results. You will feel like a different person, and your working capacity, both physically and mentally, will be immensely increased. A plentiful supply of fresh air is more necessary than food and drink. We can live without food for weeks, without water for days, but without air only a few minutes. The Process of Breathing With every inhalation, air is sucked in through the windpipe or trachea, which terminates in two tubes called bronchi, one leading to the right lung, one to the left. The air is then distributed over the lungs through a network of minute tubes, to the air cells, which are separated by only a thin membrane from equally fine and minute blood vessels forming another network of tubes. The oxygen contained in the inhaled air passes freely through these membranes, is absorbed by the blood, carried to the heart and thence through the arteries and their branches to the different organs and tissues of the body, fanning the fires of life into brighter flame all along its course and burning up the waste products and poisons that have accumulated during the vital processes of digestion, assimilation and elimination.