The condition of the heart valves included in the term subacute bacterial endocarditis has within the last fifteen to twenty years created much interest. As early as 1885, Osler1described this condition in what he called malignant endocarditis. Horder2and Billings3described it, in 1909, under the heading of infective endocarditis. Endocarditis lenta was the term used by Schottmüller4in 1910, and in the same year the term subacute bacterial endocarditis was first used by Libman and Celler.5Munzer6and Ruggeri7used the term slow endocarditis. Various phases of the subject have been considered in France by Achard and Rouillard,8Debré,9and others; in Germany by Schottmüller,4Munzer,6Hassencamp10and Moravitz;11in England by Lewis,12Horder,13Poynton,14Boyd,15Cotton,16Combs,17Gibson,18Gow19and Starling;20in Canada by Murray and Lougheed;21and in the United States by Libman and Celler,5Baehr and Lande22and others. An exact agreement among workers as