Excerpt from Introduction: The name of one of your illustrious countrymen, Louis Pasteur, will forever be remembered as the founder of the science of bacteriology. It was he who first isolated and identified a specific germ and related it to a definite clinical entity (disease). Following up on his discoveries, medical science concentrated on the laboratory technique for the isolation and identification of a specific germ for each known disease, and the Koch postulates were accepted as the standard for declaring any germ capable of pathogenesis - of having power to cause disease. The motto of the medical profession is still Tolle Causam, find the cause, and today there are many who consider that germs are the only cause of disease and are working to discover the specific germ or virus for well know clinical entities. It must now be accepted as scientific fact that, specific germs, in many cases of disease, can be isolated and identified, but is it a true conclusion that the specific germ is always the cause of disease? The subject is too great to be dealt with in all its aspects in this short session, but a little time must be given to considering the general question, namely the role of the Bacterium in Nature because one’s opinion on this must determine the value one places on the use of bacterial products - vaccines or nosodes - in the treatment of disease. As the subject of this paper deals with the intestinal flora, I propose to limit my remarks to consideration of the role played by the B. coli and coliform organisms found in the intestinal tract.