In the case which we are about to report the following features will receive consideration : a conduction defect in the main stem and the right branch of bundle demonstrable at all periods of associated contraction of auricle and ventricle ; transient periods of complete dissociation of auricle and ventricle, some of which were closely associated with digitalis administration ; a rate of ventricle which exceeded that of the auricle in all periods of dissociation, except one; the occurrence of frequent junctional premature beats during periods of normal sequence of contraction ; variations observed in ventricular complex; the apparent relation of digitalis administration with disturbances of mechanism as above noted, and with the degree of heart failure as estimated at a given time. Case History. —F. W., aged 61, a real estate broker, was admitted to the St. Francis Hospital on Nov. 17, 1915. He was transferred to medical service two days