AGE, GROWTH AND DEATH 491 



philosophies or from any of the great world religions. Nevertheless 

 he is an optimist. He has noticed as a result of his meditations upon 

 the arrangements within our bodies that we suffer very much from 

 what he calls disharmonies, by which he means imperfect adaptations 

 of structures within us to the performance of the body as a whole. 

 He mentions various instances of such disharmonious parts. They 

 do not seem to me quite so imposing as apparently they do to him, 

 for many of his disharmonies are based upon the fact that we do not 

 know that a certain structure or part has any useful role to play in 

 the body. But I am inclined to suspect that in many cases it is only 

 because we are ignorant; the list of useless structures in the human 

 body was a few years ago very long; it has within recent years been 

 greatly shortened, and we should learn from this experience a caution 

 in regard to judging about these things, which, I think, Professor 

 Metchnikoff has failed to exert duly in forming his opinions on these 

 disharmonies. Now among the disharmonies which he recognizes is 

 that of the great size of the large intestine, which is of such a caliber 

 that a considerable quantity of partially digested food can be retained 

 in it at one time. When such food is retained in the intestine, it 

 may undergo a process of fermentation. There are many sorts of 

 fermentation, and some of them produce chemical bodies which are 

 injurious to the human organism. Bacteria, which will cause fer- 

 mentation of this sort, do actually occur in the human intestine. 

 Metchnikoff thinks that, as we grow old, this tendency to fermentation 

 increases. Now the bodies produced by fermentation, the chemical 

 bodies, I mean, get into our system and poison us. The result of the 

 poisoning is that the native capacities of the various tissues and organs 

 of the body are lowered, as happens in a man ' intoxicated.' All parts 

 of a man may be poisoned, not necessarily always with alcohol, but 

 with many other things as well, and such a poisoning Professor 

 Metchnikoff assumes to result from intestinal fermentation. More- 

 over, he has further observations, which lead him to the idea that 

 certain cells go to work upon the poisoned parts and do further damage. 

 The cells in question are minute microscopic structures, so small that 

 we can not at all see them with the naked eye, but which have a 

 habit of feeding in the body upon the various parts thereof whenever 

 they get a chance. Cells of this sort go by the scientific name of 

 phagocytes, which is merely a Greek term for ' eating cells.' The 

 phagocytes, for instance, devour pigment in the hair, and in old per- 

 sons the production of white hair has resulted from the activity of 

 phagocytes which have eaten the pigment which should have remained 

 in the hair and kept its color. But the pigment of the hair is not the 

 only thing they will attack; they will make their aggressive inroads 

 upon any part of the body; and Professor Metchnikoff has advanced 

 the theory that old age consists chiefly in the damage which is done 



