HOW TO PREVENT DEGENERATION OF TISSUE It can readily be seen that if the pernicious activity of these macrophages can be prevented, the coming on of degenerative changes in the body tissue will be much delayed. The practical question, which Metchnikoff therefore asked himself was, How may this revolt of the macrophages, this rebellion of the body’s army, be prevented? It is not possible to attack the macrophages themselves without at the same time doing damage to the body. For these wandering cells are more hardy and vigorous than the higher cells by which the bodily functions are performed, and which they attack, so whatever might be done to weaken the attack of the wandering cells would to a greater degree damage the higher cells of the body. The conclusion that Metchnikoff reached was that the only direction in which we can hope for success in the attempt to prolong human life, lies in giving attention to the predisposing causes which weaken the vitality of the higher body cells and thus expose them to the successful attacks of the scavenger cells. In other words, if we are to prolong human life, we must make the conditions of life such that the premature accumulation of body wastes or poisons shall be prevented. One of the first steps to take to affect that end is, obviously, the avoidance of the introduction of poisons, and poison-forming foods, into the body. Out of all proportion to all other causes which lead to the formation of body poisons, is the production of toxins in the colon or large intestine. Metchnikoff’s studies show beyond a doubt that there is a close connection between the size of the colon and the duration of life in various birds and animals. Where the colon is used, and has attained large proportions, as in man, in the horse, and many other animals, life is comparatively short, and death is premature. Where the colon is rudimentary, or where only such foods are eaten as do not decay or ferment in the colon, then life is long. Thus the most important problem, according to Metchnikoff, is how to prevent the development of poisons in the colon. He believes that the colon, indeed, is quite superfluous, and that man would be better off without it. He quotes several curious cases in which the colon has been removed from the body, and the subjects of the operations have recovered impaired health and lived for long periods afterwards. Since the colon cannot be generally removed from the body, however, the practical problem comes down to this: How may we avoid the evils which result from the fermentative and putrefactive processes which go on in this organ?