During the past few years there has been a great revival of interest in the bacteriology of the digestive tract. The investigations of Moro,1 Tissier2 and others, especially Herter and Kendall3 in this country, have explained the discrepancy noted since the days of Escherich, that the number of bacteria in the dejecta is much greater than the number of colonies which develop on our plates. They have demonstrated that the gram-positive organisms found in smears of the intestinal contents are equally important with the gram-negative, that they can be freed from the ordinary intestinal bacteria by cultivation in acid broth, and that they are just as much obligate inhabitants of the alimentary canal as are Bacillus coli communis and Bacterium lactis aerogenes. The old theory that Bacillus coli is gram-positive in the intestines and gram-negative in our cultures was thus proved to be untenable, as was usually