We also generally observe perspiration in all processes of infection or intoxication, and it may therefore be regarded as a probable species of self-defense of the human body against the attacks of microbes or other toxic products, for it would seem that by this means nature desires spontaneously to get rid of the various toxic matters. Indeed, when we treat fever with salicylates we are assisting nature to this end, for we thus create perspiration. As already mentioned in Chapter III, persons with a dry skin, who perspire but rarely, have less protection from infectious diseases than others. Thus everything supports the theory that the various toxic products, including those from microbes, are eliminated by perspiration. Many years ago we tried to find microbes in the sweat of typhoid fever patients in the St. Pierre Hospital in Brussels, but as has been found in the bacteriological laboratory of the Institute Solvay, the cultures that formed were due to a pollution of the perspiratory products with foreign microbes. The efforts of other authorities have also failed up to now to discover, by exact research, the presence of microbes in sweat, as expressive of their elimination through sweating. But, even if not supported by exact evidence, we feel inclined to believe that by perspiration in abundance a number of toxins of bacterial origin can be eliminated from the blood, because in feverish ailments, after great perspiration, as in the case of pneumonia, a great improvement takes place in the condition of the patient. In former times bleeding gave similar results, perhaps in a greater degree; but in the present day sweating has superseded this. To the hygiene of the skin through bathing we would wish to add, before concluding this chapter, that carbonic acid baths may also give good results, as they cause a better circulation of the blood through the skin, which gets red. Such baths are also excellent preventatives against arteriosclerosis. ------------------------------------------------------------------------ CHAPTER XXVIII. ON EXERCISE, SWEDISH GYMNASTICS—MASSAGE—SPORT, AND WALKING AND RUNNING EXERCISE. ALL kinds of exercise have one essential point to them—they produce a contraction of the muscles. As Ludwig and his disciples have shown, contraction of the muscles produces an increased supply of blood in them; more arterial blood being brought to the muscles, more oxygen and heat is generated through them, which results in a general increase of the process of oxidation.