=Nauwerck Method.= By this method the left auricle, left ventricle, right auricle and right ventricle are opened in succession. The heart is seized in the left hand, and without rotation is drawn upon the right edge of the ribs. Beginning in the upper left pulmonary vein or between the veins an incision is made through the wall of the auricle to the sulcus circularis, avoiding any injury to the coronary vessels. Beginning below the mitral ring an incision is carried along the left ventricular ridge to the apex. The left auricle and ventricle are then cleared of blood and the mitral opening examined. The heart is then put back into its natural position; the left thumb is placed in the apex of the left ventricle and the four fingers passed over the right border of the heart to its posterior surface, rotating the heart to the left until the right auricle is brought uppermost. (See Fig. 40.) Then an incision is made through the wall of the right auricle, beginning midway between the superior and inferior venæ cavæ and extending to the tricuspid ring, then begun again 1 cm. below, is carried along the right border of the heart, or slightly anterior to it, as far as the septum. (See Fig. 40.) The contents of right auricle and ventricle and the tricuspid valves are now inspected. The heart is then removed from the body by lifting it up vertically as far as possible and cutting the vessels from below upward as close as possible to their exits through the pericardial sac. The hydrostatic test is then applied to the aortic and pulmonary valves by pouring water into these vessels, or by immersing the heart an water and then lifting it out. The heart is then laid flat on the board with apex toward the operator. The enterotome is introduced into the right ventricle and through the pulmonary orifice and an incision made through the anterior wall of the right ventricle, beginning just above the anterior papillary muscle at about the middle height of the ventricle, and cutting through the pulmonary conus and pulmonary valve well to the left, close to the septum, following the narrow ridge of fat at the base of the artery so as to pass between the left anterior and posterior segments. The heart is then rotated on its vertical axis so that the right auricle is turned toward the prosector, and the tricuspid ring is opened with the intestinal shears. The auricular appendage is then cut open from the auricular incision. The heart is then held in its former position and an incision is made in the anterior wall of the left ventricle just to the left of the septum, from the apex through the aortic ring and the left wall of the aorta, while the pulmonary artery is pulled to the right. (See Fig. 41.) Care must be taken not to damage the right border of the base of the mitral; the cut should pass half way between the pulmonary orifice and the left