Resolution of the other portions of the involved lobes in influenza is not so easily accomplished. Where a progressive lesion with its development of pus occupying both the air sacs and the tissue of the lung, the outcome of attempts at repair are uncertain. Complete resolution with complete disappearance of the purulent exudate may take place as we see it in many other regions occupied by a similar reaction; and where the purulent response is not accompanied by material damage to the tissue the restoration of the lung is so complete that upon its recovery no evidence is left behind of the former injury, but in as much as the presence of a purulent reaction in the lung is often of more severe grade than this, a certain amount of tissue destruction having been accomplished, the repair does not completely restore the tissue to its former normal state. The purulent lesion, however, is not uncommonly accompanied by minute capillary thromboses, tissue derangement, organic destruction, with even tissue alteration amounting to abscess or gangrene, and it is too much to hope that the lung may be completely restored. Minute abscesses varying from microscopic size to large cavities, several centimeters in diameter, were not unusual in the tissues severely involved in the purulent reaction. Thus in these areas, resolution can be accomplished only by a process of slow organization of the damaged parts with the final production of fibrosis. These fibroses are of variable extent depending upon the initial damage. We have been very much struck with the speed with which this process of organization may take place and the extent of the lung tissue which may become involved in this late lesion. In one of our cases we have evidence of marked fibrosis present on the twenty-third day of his illness. Patches of organization varying from one to four centimeters in diameter occupied the different lobes of the lung. The new fibrous tissue was well developed and the purulent reaction had largely disappeared. The fibrosis obliterated the normal architecture of alveoli and bronchioles, leaving only irregular islands of epithelium which assumed grotesque glandular shapes and looked not unlike a new growth. One of the interesting features of these late fibroses which come to occupy various extents of the lung and bronchial tissues is that the individual after recovering from his acute influenzal lesions again passes, in about his third week, into a stage of dyspnœa with manifestations out of proportion to the physical signs or constitutional derangements which can be determined. The dyspnœa is often the outstanding sign and the patient may die in a state of asphyxia.