The instructive Address on State Medicine given by Dr. W. H. Welch, of Baltimore, at the recent meeting of the Association, should emphasize anew in the mind of every general practitioner the oft taught, but oft neglected, lesson, that the physician's duty in cases of infectious disease is but half fulfilled in his most solicitous care for the patient's individual welfare. To prevent the extension of the malady from the sick-room to the household—from the household to the community, is an even more important obligation.
Although the mystery of the vera contagia is still unsolved in a strictly scientific sense, enough is known of the ordinary conditions of their evolution and transmission in many instances to facilitate the application of what we may venture to call "clinical hygiene." Aside from all theoretical controversies concerning the part played by microörganisms—as causes, carriers, or merely ferments operative only in suitable media—we know