It has been, perhaps, Metchnikoff’s crowning discovery, that the immediate cause of old age is not merely the accumulation of poisonous wastes, but is due to a destruction of the tiny cells which make up the tissues by certain cells of the body, which he describes as macrophages. These are of an especial kind, which wander through the body and devote their energies to the destruction of waste particles and organic débris—particles of material which are not used in the building up of tissue, just as particles of brick and wood might be left on the ground after the erection of a house. These macrophages enact the part of scavengers, very much like the turkey buzzards, which in southern cities eat up the refuse from the back alleys. Just so long as these wandering cells confine themselves to this useful and necessary work, all goes well; but when the vigor of the body cells has been lowered by the accumulation of tissue poisons, these scavenger cells turn traitor to the cause of the body and attack the very cells which they formerly guarded. They have been photographed in the very act of devouring nerve cells in the brains of old people.
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?
If the large intestine is kept clean, if only those foods which are antitoxic are eaten, then there will be very few poisons generated in the colon, and the health of the body will be maintained in a higher degree and for a much longer period than can be possible when toxic foods are freely partaken of. It is here that the great argument for vegetarianism on its scientific side arises. All meats and fish are not only “toxic” foods in themselves, but they are quite likely to contain parasites of various kinds.
Ordinary bread has been shown to contain a sufficient amount of proteid to supply all the body needs, as do also rice and other cereals and potatoes. Nuts and dried peas and beans are exceedingly rich in proteid, like meat, and therefore should be eaten sparingly. The best foods in the order of excellence are given by Dr. Kellogg, as follows—the antitoxic foods being in italics: fresh ripe fruits, cooked fresh fruits, cooked dried fruits, nuts, cooked cereals, rice, zweibach, toasted corn flakes, potato, cauliflower, and other fresh vegetables, honey, malted nuts, yogurt, or buttermilk, sterilized milk, and cream, peas, beans, lentils, raised bread, and sterilized butter.
HOW TO ENLIST THE SERVICES OF FRIENDLY GERMS
Since the poisons which are produced in the colon are due to the growth and cultivation of germs, the remedy which naturally suggested itself to a bacteriological specialist like Metchnikoff was to find some harmless or comparatively harmless germ with which the poison-forming germs might be fought—or, in other words, to introduce into the body an extra battalion of soldiers to assist the warrior cells in the battle of the blood.