In over 80 per cent of instances of pulmonary abscess hemolytic streptococcus has been found in blood, lungs and bronchus and, when cultures have been made, in the inflamed pleural cavity as well. Streptococci have been found in immense number in sections from the necrotic lung tissue and the abscesses which have been formed. It is evident that hemolytic streptococci have caused suppurative pneumonia and death, being found in the blood of the heart just as frequently as in the lungs (83 per cent). The relative unimportance of pneumococci is indicated by their low incidence in the blood (16.2 per cent) when compared with that of lobar pneumonia (65.5 per cent) or of bronchopneumonia (31.4 per cent). B. influenzæ has been found in three-fourths of these autopsies in the bronchus, but its incidence in the lungs has been much smaller. In 3 instances of suppurative pneumonia with abscess formation no hemolytic streptococci were found; they are as follows: =Autopsy 380.=—Bronchopneumonia with gray and red lobular consolidation in right upper and lower lobes; peribronchiolar nodules of consolidation in left lower lobe; abscess, 1.5 cm. across, below the pleura of the posterior border of the left lower lobe near its base; fibrinopurulent pleurisy (300 c.c.) on right side; serous pleurisy (200 c.c.) on left. Pneumococcus III was found in cultures from the blood of the heart from the right lung and with B. influenzæ from the right pleural cavity. No culture was made from the left lung which contained the abscess. In sections of the abscess gram-positive streptococci in chains of 4 to 8 cocci were numerous. =Autopsy 406.=—Acute lobar pneumonia with red hepatization of greater part of right lung; patch of consolidation in lower lobe of left lung containing an abscess cavity 2.5 x 1.5 cm.; localized seropurulent pleurisy (375 c.c.) on left side. Pneumococcus IV was obtained from the blood of the heart; a culture from the lung was contaminated. Tissue from the abscess was not saved for histologic examination. =Autopsy 416.=—Suppurative pneumonia with necrosis and abscess formation in right lower lobe; fibrinous pleurisy on right side. Pneumococcus IV was obtained from the blood, right lung and right main bronchus. No streptococci were found in sections from the abscess in the right lung. The foregoing observations demonstrate that suppurative pneumonia with abscess formation following influenza is with few exceptions caused by S. hemolyticus. The autopsies (Table XLVI) in which pneumococci have been found in association with hemolytic streptococci in the blood or lungs indicate that pneumococci have had a part in the production of fatal pneumonia. TABLE XLVI