INTRODUCTION
It is commonly believed that the character of the bacterial flora of the gastro-intestinal tract has an important influence on health. In certain instances this is unquestioned. The implantation of sufficient numbers of certain bacteria, B. typhosus, B. dysenteriae or Vibrion cholerae in the absence of a counteracting general bodily immunity brings about the development of the infections specifically related to these organisms. So also, but possibly in a less specific way, the less well characterized gastro-intestinal disturbances of infancy and childhood are commonly supposed to be due either to the activity of particular species of bacteria or to an alteration in prevailing types of micro-organisms.A relationship between the general type of bacterial flora prevailing in the gastro-intestinal tract and more obscure disorders, such as anemias and ill defined general intoxications, is often surmised, but scientific evidence of such an association cannot be said to have been presented