Among infants there is a distinct seasonal incidence of disease. At the Babies' Hospital, to which contagious diseases are not admitted, the character or type of the ward cases varies with the seasons, although the quantity (numbers and severity) varies from year to year. Thus, for example, the number of cases of pneumonia increases from early fall until late winter, to be followed by empyema and then in the early spring by tuberculosis. The late spring is a hang over season for tuberculosis and empyema, and in the early summer the intestinal diseases begin to appear. There are few of these in June; they increase in number through July and August, and diminish after the middle of September. Frequently, however, the severest intestinal lesions are found at necropsy in October, among children whose illness has lasted five or six weeks or who give a history of mild diarrhea earlier in