Sections from the least involved areas of the lung show a subsidence of the alveolar exudate and the walls are no longer intensely engorged. Perhaps the most prominent feature within the alveoli is the desquamated cells, presumably alveolar cells with broken or pyknotic nuclei. Despite the fact that so many cells of this type occupy the lumen of the alveolus, its wall has a prominent lining of cubical epithelium. Often mitotic figures abound in this new alveolar epithelial lining (Fig. XLVII), an evidence of rapid regeneration in that portion of the lung where the initial irritative process has subsided and where the destruction has not been as deep as elsewhere (79). This picture may be taken as positive evidence of an initial, diffuse, and general pulmonary involvement, which, with the subsidence of the primary reaction, is followed by localization resulting in the different types of consolidation now encountered. [Illustration: FIG. XXI. AUTOPSY NO. 95. A TYPICAL APLASTIC ALVEOLAR EXUDATE COMPOSED Of RED BLOOD CELLS, FIBRIN, AND BACTERIA. COMPARE FIGURES XX, XXII, AND XXIII. HELIOTYPE CO. BOSTON ] [Illustration: FIG. XXIII. AUTOPSY NO. 175. NOTE THE ABSENCE OF ALVEOLAR EPITHELIUM, THE ENGORGEMENT OF THE VESSELS OF THE ALVEOLAR WALLS, AND THE SEROUS EXUDATE. ] [Illustration: FIG. XXV. AUTOPSY NO. 92. THE EXUDATE CONSISTS ALMOST ENTIRELY OF A MASS OF RED BLOOD CELLS. THE DESQUAMATED ALVEOLAR EPITHELIUM IS SCATTERED THROUGH THE HEMORRHAGIC EXUDATE. COMPARE FIGURES XXIV AND XXVI. ]