5. =Section of the Lungs.= The general inspection of the pleural cavities and pleural surfaces is made as soon as the thoracic cavity is opened, as indicated above. If a pneumothorax is present the pleural cavity on the affected side is filled with water, the neck organs are exposed and a tube inserted into the trachea. When air is forced through this bubbles will escape from the perforation and the opening can be easily located. When extensive or complete pleural adhesions are present, so that they cannot be separated, it becomes necessary to remove the costal pleura in connection with the visceral layer. This is accomplished by loosening the costal pleura and subpleural fascia at the cut edge of the ribs with the blade of the knife, until the fingers and, finally the hand, can be worked in between the costal pleura and the chest-wall, gradually separating the two until the entire lung is freed with both layers of pleura adherent. Firm adhesions at the apex may have to be cut with the knife. Similar adhesions with the pericardium or diaphragm may make it necessary to cut out the adherent portion with scissors or knife and remove it in connection with the lung. When the pleural adhesions are very firm upon the right side the prosector may find it most convenient to stand at the left side of the cadaver and from this position separate the right costal pleura from the chest wall. An assistant may be of great service in pulling the thoracic wall outward. The edge of the ribs or cartilages may be covered with a towel or the skin may be drawn over it to protect the hands. In extreme cases it may be necessary to saw the ribs and remove them in connection with the lungs. Sometimes the adhesions may be separated more easily if the neck-organs are first removed down to the clavicle, and then, in connection with the lungs, are removed _en masse_, by means of powerful tugs, from above downward. The apical and posterior adhesions may be torn fairly easily in this way when ordinary manipulations in the thoracic cavity have no effect upon them. When the pleural surfaces are free the =left lung= is lifted out of the cavity onto the right edge of the chest-wall, pulling it forcibly over to the right so that its posterior surface becomes uppermost. In this position the lung may be sectioned by one or more main incisions made with the long section-knife, cutting the organ from apex to base, down upon the ribs in the direction of the main bronchi and vessels. After the examination of the cut surfaces the organ may be returned to the cavity. It is better, however, to remove the lung, and section it outside the body. This is done by cutting the mediastinal pleura, pulmonary vessels and main bronchus with the cartilage-knife, while the lung is held upon the right edge of the thoracic opening, holding the knife so that its blade strikes the edge of the costal cartilages. [Illustration: FIG. 42.—Section of left lung. (After Nauwerck.)]