INFECTIVE LESIONS OF THE LUNG WHICH CONCERN THE SURGEON. The surgical infective lesions of the lung are abscess, bronchiectasis, gangrene, foreign bodies, cysts (echinococcus and dermoide), tuberculosis and actinomycosis. Abscess of the lung is not as common a pulmonary affection as might be inferred from the number of cases reported as such in the literature. A careful scrutiny shows that a considerable percentage of the cases reported as abscesses are empyema communicating with the bronchus, subdiaphragmatic abscess rupturing into a bronchus, or circumscribed interlobar pleurisies. Abscess—Etiology.—The most common cause of abscess of the lung is: 1, acute circumscribed inflammation, as pneumonia, followed by necrosis and softening of the lung, 46 per cent.; 2, peribronchitis; 3, septic embolism of the pulmonary artery, or a single branch of the bronchial (pyemic embolism), 3 per cent.;434, rapid tuberculary caseation and necrosis, with secondary infection; 5, perforation of the lung by infection from malignant diseases