29. It is necessary to examine the pharynx and gullet, the larynx, trachea, and its greater ramifications, the lungs, the heart, and the great vessels with particular care, because here are most frequently found the causes of sudden natural death. In examining the heart each auricle and each ventricle ought to be laid open by an independent incision of its parietes; and this should not intersect any of the valvular openings or the septum cordis. 30. For laying open the chest and abdomen, the most convenient method is to make an incision down the fore part of the neck, chest, and abdomen to the pubes; then cutting from the peritoneum upwards, to dissect back the integuments and muscles of the chest, and examine the abdomen, as in Sect. 22; next, divide the cartilages of the ribs, and, cutting upwards, close under them, to raise the cartilages along with the sternum. In separating the sternum from the clavicles, care must be taken not to wound the subjacent vessels; and this may be avoided by the dissector moving each shoulder so as to show the exact position of the sterno-clavicular joints, and then dividing both joints cautiously. In dividing the cartilages of the ribs, the saw is sometimes necessary. The cartilages should be cut as far from the sternum as possible, to give free space for the subsequent examination. 31. In inspecting the organs in the chest, a cursory examination should be first made by turning them over, ascertaining the nature and measuring the quantity of effused fluids, feeling for fractures of the ribs, tumours, or other diseases, and opening the pericardium to obtain a view of the heart. The most convenient course to pursue next is, without moving the heart from its place, to lay open its several cavities, in order to judge of the quantity and state of the blood in both sides of that organ. For this purpose the following incisions should be made: The _first_, beginning close to the base, is carried along the right border of the heart directly into the right ventricle towards the apex, care being taken not to cut the septum. This lays open the right ventricle. The _second_ incision, opening up the right auricle, begins midway between the entrances of the venæ cavæ, ending just in front of the base. The _third_, for exposing the left auricle, commences at the left superior pulmonary vein, and ends just in front of the base, close to the coronary vein, care being taken not to wound it. The _fourth_, displaying the left ventricle, commences behind the base, and ends close to the apex. If the blood is in a fluid state, the quantity contained in the right auricle may be materially affected by the head being examined previously, as the blood may have escaped from the heart by the jugular veins. The whole of the organs in the chest--the lungs, heart, and gullet--together with the parts dissected downwards from the throat, should now be removed in one mass, in order to examine them in detail on a table.