_Dissection of the contents of the thorax._—An incision must be made through the integuments, in a straight line from the _os hyoides_ to the navel; we are then to open into the cavity of the abdomen, for the sake of affording the anatomist free space for his dissections in the chest; and this is to be effected by incisions from the navel to each spine of the ilium, so that we shall have thus described by our dissection a figure resembling the letter Y inverted, thus [Inverted Y]. In performing this part of our labour, it is essentially necessary to avoid puncturing or injuring any of the viscera; where such a blunder has been committed the dissection has lost much of its value. The integuments of the breast are then to be carefully dissected so as to expose the cartilaginous articulations of the ribs, which must be cut through on both sides; the clavicles should also at the same time be separated from the sternum, by dividing the loose cartilage which unites them. The latter bone, together with the cartilaginous portions of the ribs, must be next turned upwards over the face, so that the cavity of the thorax shall be brought into view. In some cases it will be found expedient to make a still more extensive exposure of this cavity; for which purpose a broader flap must be turned up in front, by extending our dissection of the parietes of the thorax farther towards the back; and, instead of cutting through the cartilaginous extremities of the ribs, dividing the bones themselves with a saw. In bending back the sternum, or flap in front, we must take care and divide the _mediastinum_ with the scalpel as near the bone as possible, in order to avoid making any opening into the _pericardium_, which would otherwise be very apt to happen. As soon as an opening is effected into the thoracic cavity, the lungs collapse, unless the adhesions formed between them and the pleura should prevent it. Our first object will be to observe whether any quantity of fluid is present in the chest, and whether it be limpid, as in dropsy; turbid and containing flakes of coagulated lymph, as in cases preceded by much inflammatory action; or purulent, as in empyema. Having removed the liquid, should any be present, by the application of a large sponge, we must proceed to examine the lungs, as to their colour and general appearance; and, by the introduction of a blow-pipe into the trachea, we should by means of the mouth or bellows inflate these organs, so as to ascertain the degree of distention of which they are susceptible. We may at the same time inspect their structure more minutely by raising each lobe with the hand, introduced into the cavity of the thorax for that purpose. We are next to cut into their substance in order to observe whether they are gorged with blood, and inflamed; whether they are crepitous and light, or dense like liver; and whether they contain any tubercles; should these latter bodies be discovered, we have to ascertain their magnitude, extent, and maturity, and whether any of them have been developed into _vomicæ_. The anatomist should be cautioned not to mistake the deep colour, and compact texture which occur in the depending portions of the lungs, from the mere accumulation of blood in consequence of gravitation, for an inflamed state of the organs; in which latter case a crowd of fine vessels injected with blood of a florid colour furnish a diagnosis that cannot be mistaken.