The character of the exudate in the alveoli surrounding the bronchus differs considerably in different instances. In some instances (Autopsies 374 and 392) red blood corpuscles are predominant in the alveoli in contact with the bronchial wall, whereas in a peripheral zone polynuclear leucocytes are more abundant. In other instances (Autopsies 253 and 402) alveoli next the bronchial wall contain abundant fibrin and these are surrounded by a zone in which the alveoli are filled with blood. Peribronchial pneumonia is the result of the direct extension of the inflammatory process through the wall of the bronchus; it occurs when the epithelium of the bronchus is destroyed and the underlying tissues are injured, but may be present in a wide encircling zone even when the lesion has not penetrated the bronchial wall. The distribution of the pneumonia demonstrates very clearly that the inflammatory process does not reach the affected peribronchial alveoli by way of the bronchioles tributary to the bronchus. The bacteriology of these instances of peribronchial pneumonia is noteworthy. (Table XLII.) TABLE XLII ═════════════════╤═════════════════╤═════════════════╤═════════════════ AUTOPSY │ BLOOD │ LUNG │ BRONCHUS ─────────────────┼─────────────────┼─────────────────┼───────────────── 253 │Pneum. II │Pneum. II, B. │Staph., B. inf. │ │ inf. │ 374 │Pneum. IV │ │ 387 │Pneum. II, S. │Pneum. II, │Pneum. II, S. │ hem. │ staph., B. inf.│ hem., staph., │ │ │ B. inf. 392 │Pneum. II │ │ 402 │Pneum. IV, S. │ │ │ hem. │ │ 424 │? │Pneum. IV │ ─────────────────┴─────────────────┴─────────────────┴───────────────── Pneumococcus has been found in every instance either in the lungs or blood. Pneumococcus II, which has been uncommon with the pneumonia following influenza at Camp Pike and has occurred only ten times in more than 200 autopsies, has been present in one-half of these cases. The constant association of the lesion with pneumococcus is particularly significant when a comparison is made between the incidence of pneumococcus with peribronchial hemorrhage, on the one hand, and peribronchial pneumonia on the other; pneumococcus has been present in less than a third of the instances of hemorrhage but in all instances of pneumonia.