_Post mortem_ appearances.--In acute cases, the cadaverous lesions chiefly consist in abundant false membranes in the trachea, or windpipe, and closure of the bronchial tubes by plastic lymph. The air-vesicles are completely plugged by this material, and very interesting specimens may be obtained by careful dissection, in the shape of casts of the bronchial tubes and air-vesicles, clustered together like bunches of grapes. On slicing the lungs in these cases, hepatization is observed, presenting a very peculiar appearance, which is, in a great measure, due to the arrangement of the lung-tissue in cattle. The pulmonary lobules are of a deep-red or brown color, perfectly consolidated, and intersected or separated, one from the other, by lighter streaks of yellowish-red lymph, occupying the interlobular, areolar tissue. In the more chronic cases, the diseased lobes and lobules are found partly separated from the more healthy structures. This occurs from gangrene, and putrefactive changes, or in some instances, from the ulcerative process, so constantly observed in the segregation of dead from living tissues. Abscesses are not infrequently found in different parts of the lungs. Sometimes circumscribed, at others connected with bronchial tubes, and not infrequently communicating with the pleural cavity. True empyema is not often seen; but, at all times, the adhesions between the costal and visceral pleura are extensive, and there is much effusion in the chest. In dressed carcasses of cows that have been slaughtered from pleuro-pneumonia, even though the disease has not been far advanced, it will be found that the butcher has carefully scraped the serous membrane off the inner surface of the ribs, as it would otherwise be impossible for him to give the pleura its healthy, smooth aspect, from the firm manner in which the abundant false membranes adhere to it. The diseased lungs sometimes attain inordinate weight. They have been known to weigh as much as sixty pounds.