to study the immunologic response of the patient to its action. It is the purpose of this study to ascertain the practicability of laboratory methods now available for the study of this disease. Epidemiological and clinical aspects.-Epidemiologically and clinically the 1940-41 outbreak of epidemic influenza in St. Louis1 resembled those which have occurred repeatedly since the pandemic of 1918-19. The outbreak under investigation started suddenly on February 10, 1941, and continued for about 3 weeks. Between February 10 and February 15, 46 (40%o) children in the institution were hospitalized with an acute febrile upper respiratory disease diagnosed as epidemic influenza. Two days prior to the outbreak 15 boys attended a joint Boy Scout meeting with troops from all sections of the city. Twelve of these 15 boys developed an acute respiratory infection. Since the boys are not usually associated with outside children and since no other contacts could be traced, it may be assumed that the Scout meeting was the source of the infection. The onset of the disease was abrupt with predominating symptoms of fever, headache, generalized body aches, prostration, slight throat irritation, and persistent dry cough. No unusual findings were observed on physical examination. The uniformity in the clinical aspects of all patients was remarkable. The fever subsided in 3 to 5 days, and none of the children developed any complications. Recovery of influenza virus.-Though the ferret is the animal of choice for the