Here Metchnikoff formulates an optimistic view of man's relationship to disease, old age, and death based on his discovery of "phagocytes", the chief function of which is to devour intruding microbes. The scientific importance of this work was so great that it was spoken of in England as the most valuable production since Darwin's Origin of Species. Elie Metchnikoff (1845-1916) was Sub-Director of the Pasteur Institute, and a Nobel Prize winner for...