The right pleural cavity contains 85 c.c. of thick purulent fluid; the right lung (Fig. 9) is collapsed and pushed to the median line, being bound by firm adhesions to the pericardium. Over the external and basal surfaces is a localized cavity walled off by adhesions. An abscess cavity in the lower part of the lower lobe communicates through a perforation in the basal surface of the lung with the pleural cavity and is in free communication with a small bronchus. About the abscess the lung is red and laxly consolidated, but elsewhere air containing; throughout the lower half of the lower lobe, the interlobular septa are marked by conspicuous yellowish gray lines about 1 mm. in thickness. Between these thickened septa the lung tissue contains air. The lung weighs 600 grams. The left lung (Fig. 10) is voluminous and heavy, weighing 1,320 grams. The surface is everywhere covered by thickened pleura and fibrin, the pleural cavity containing 150 c.c. of thick purulent fluid. The lung is consolidated varying in color from a fleshy red to yellowish gray. The surface is very conspicuously marked by yellow lines 2 or 3 mm. thick, corresponding to the interlobular septa which have undergone suppuration. The septa have bead-like swellings along their course, and when pus escapes from the cut surface small cavities remain at the site of these swellings. Bacteriologic examination has shown hemolytic streptococci in the blood, left lung, right and left pleural cavities, and right bronchus. B. influenzæ has been found in the bronchus, in the right pleura and in the heart’s blood. A few colonies of S. aureus have been found on the plate from the right pleural cavity (site of thoracotomy). Microscopic examination of the right lower lobe shows that the interstitial septa are much thickened by young fibrous tissue infiltrated with lymphoid and a few plasma cells. Large mononuclear cells with granular cytoplasm are very numerous. A lymphatic is much distended and contains a few polynuclear leucocytes and many lymphoid and large mononuclear cells. There is no suppuration. Sections from the right lung show suppurative lymphangitis with suppurative inflammation of interstitial tissue. The right lung is the site of a healing lesion of the interstitial tissue which has developed simultaneously with acute interstitial suppurative pneumonia in the left lung. Both lesions are doubtless caused by S. hemolyticus. This healing lesion exhibits little similarity to the interstitial bronchopneumonia described by several observers with both measles and influenza. The following autopsy furnishes further evidence that interstitial suppurative pneumonia exhibits a tendency to heal. Proliferation of endothelial cells lining the inflamed lymphatics gives rise to phagocytic cells which aid in removing the accumulated leucocytes.