Abstract
Two epidemics among mice are described that were closely associated with Morgan's No. 1 bacillus. In both of these epidemics the mice, which were fed on oats and raw beef, were found at autopsy to be suffering from peculiar lesions—an advanced degree of anaemia, pale and swollen kidneys, and general pallor and dryness of the tissues—not hitherto encountered in any other epidemic. Evidence is advanced to show thatBact. morganiwas the specific cause of these epidemics; and it is suggested that the peculiar lesions described were the result of a chronic intestinal infection with this organism.The close analogy existing between the bacteriological findings in summer diarrhoea and in our experiments is discussed. The tentative conclusion is advanced that summer diarrhoea is not a bacteriological entity, but is a disease that can be caused by a number of different members of the non-lactose-fermenting group.