In the succeeding chapters we will enter fully into detail on all the subjects we have touched upon in these general remarks. We will describe the functions by which the body rids itself of toxic products, and the means by which these functions may be improved. At the same time we shall set forth the rational hygiene of the organs that cause the elimination of poisons either taken through food or introduced from without; and after having demonstrated the most effective mode of freeing the body from such poisons, we shall mention the best kinds of food and deal more specifically with the advantages and disadvantages of the various kinds of food. The effects of certain agencies of great benefit to the health, such as the open air, sunshine, exercise, etc., will be treated in an exhaustive way. Finally, we shall show that we are able to prevent premature old age in an effective manner, and even to treat successfully by means of certain drugs and organic extracts the condition of old age itself. ------------------------------------------------------------------------ CHAPTER X. THE DESTRUCTION AND ELIMINATION OF TOXIC PRODUCTS FROM THE BODY AND HYGIENIC MEASURES FOR THE IMPROVEMENT OF THESE FUNCTIONS. THERE is not one thousandth of an inch of our body surface which does not swarm with innumerable bacteria, and as soon as the continuity of our skin is severed, as by a small wound, they immediately invade our tissues and attack us. Happily we are not without means of defense. Our organism is so well arranged that, as soon as a foreign body enters which might become injurious, a kind of police organization comes into action, and the leucocytes, like policemen, arrest the bacilli, and render them harmless by eating them up. This is phagocytosis, first described by the great French investigator, Metschnikoff. And so marvelously arranged is our body, that there are also special substances, the alexins (Buchner), which aid the leucocytes, and the opsonins, which first act upon the bacteria, so as to make them more digestible for the leucocytes. To make the bacilli still more sensitive to the influence of the alexins there are the agglutinins, observed by Bordet, and by Gruber and Durham, which immobilize the microbes, and thus aid the phagocytes and alexins in the performance of their task. The leucocytes are formed in the lymphatic tissues, especially the lymph glands and spleen. Thence they circulate through the body and offer opposition to the microbes and other foreign bodies which they meet on their way. The red blood-corpuscles of the adult are formed chiefly in the bone marrow.