Of the different baths which are used to induce perspiration we award the preference to electric light baths, where we obtain a double advantage, for we can unite the advantages of perspiration with those of the influence of light upon the body. We are able to prepare such a bath so that the chemically active rays (see chapter on the advantages of sunshine) are obtained. Not only is a very abundant perspiration produced (indeed sometimes about a liter of sweat can be removed from the body in from twenty to twenty-two minutes), but also the processes of oxidation can be augmented. As a consequence we often note a great diminution of fat in persons with a superabundant accumulation of this substance. When in such baths blue light is used and the blue rays are acting in overwhelming quantity, the condition of the nervous system can be influenced in a very favorable way, and especially can excited conditions be calmed. It is also probable that by such sweating procedures toxic products, which are deleterious to the nervous system, can be removed. Perspiration can also be caused by bodily movement through exercise. In such cases, as proved by physiological experiments, impulses are sent to the vasomotor centers, which result in a widening of the capillaries through the excitation of such centers. Thus sweating is created by fast walking, running, and frequently also by horseback riding, and by various kinds of sports, such as cycling. In all these cases it is essential, however, to change the clothes and underwear which we have worn when perspiring, and to take a bath; for the possibility is not to be denied that a part of the toxic products which adhere to the skin after such sweating exercises may be re-absorbed, although we are not in a position to give exact experiments to prove such a supposition. Taking a bath and using soap and brush, and creating a friction until there is a red reaction of the skin, may then prevent the danger of catching cold, but after such a bath it is most important not to leave with a hot, red skin and opened pores, but to cause their contraction by a quick cold douche, continued at intervals until the skin is cooled and the pores thereby contracted. An energetic friction of the skin must follow before leaving the bathing place. After such a bath we shall experience a sensation of great comfort, and shall feel much lighter and fresher. Such baths should be taken frequently, at least once a week, and if we are very desirous of keeping a youthful appearance for a long time, even more frequently. In stout people, however, it is necessary for such baths that the muscles of the heart be not degenerated; and also that there should be no serious affection of the heart valves or of the blood-vessels, if baths of a very high temperature and lasting a considerable time are indulged in.