We desire to call attention to a phenomenon which we have noted in the course of routine blood pressure determinations by the auscultatory method. It has doubtless been observed by others, but so far as we know there is no mention of it in the literature. It will be recalled that Korotkoff, in first describing the auscultatory method of blood pressure determinations, called attention to the fact that in lowering the pressure in the cuff from above the systolic pressure down to zero a succession of sounds was heard over the artery below the cuff. The initial sound, first audible when the cuff pressure corresponded to the systolic pressure, was of a sharp, tapping character, which, as the pressure in the cuff continued to fall, changed into a loud hum; then, still later, into a tapping sound again and finally into silence. Later observers divided this return of the tapping