Gentlemen,—At the close of my last lecture I asserted that the bruit of the heart does not reside in the organ itself, that is to say, is not produced by any mechanism in the interior of the heart, or by a concurrence of circumstances independent of the surrounding organs. I showed you this clearly in the heart of the swan, whose sternum we removed. Upon opening the pericardium and placing the ear close to the heart, or even employing the stethoscope, no bruit or sound of any kind was to be distinguished.