Etiology.—The concensus of opinion is one expressed by Winchell and Stillman1 in discussing the relationship of B. influenzæ to epidemic influenza. He believes that no matter what the etiologic relationship is, there can be no doubt about its importance as a secondary invader in this type of respiratory infection. The frequency of occurrence of B. influenzæ in the throats of normal persons has been as great in the period subsequent to the epidemic as it was during that time. It may persist in the throats of healthy carriers for a considerable length of time. Kolmer,2 as a result of complement fixation, phagocytosis and agglutination tests, reaches the same conclusion, and shows that B. influenzæ played the most important rôle in the disease as an organism of secondary infection, if not the actual or primary etiologic agent. However, no definite proof has been submitted that B.