In the 13 cases of superimposed hemolytic streptococcus infection occurring during the course of pneumococcus pneumonia, bacteriologic examination of the sputum by direct culture and by mouse inoculation shortly after onset of the pneumonia showed Pneumococci (atypical II once, Type III once, Group IV eleven times) B. influenzæ present in large numbers, and no hemolytic streptococci except in 4 instances in which a very few organisms were present. Subsequent invasion of the lower respiratory tract by S. hemolyticus was shown to occur by means of cultures of empyema fluids or by cultures made at necropsy. =Clinical Features.=—The 4 cases of hemolytic streptococcus pneumonia following influenza that occurred in this series resembled in all respects the secondary streptococcus pneumonias of the winter and spring of 1918 and presented no features requiring special comment. The onset resembled that of pneumococcus bronchopneumonia, the disease appearing to develop as a continuation of the preceding influenza. The sputum was profuse and mucopurulent in 3 cases, mucoid and bloody in the other. Two cases ran a severe and rapid course with the development of empyema early in the disease and fatal outcome. The other 2 cases ran only moderately severe courses without developing empyema and recovered by lysis in twenty and fifteen days, respectively, after the onset of influenza. Clinical differentiation between streptococcus and pneumococcus bronchopneumonia following influenza did not seem possible without bacteriologic examination of the sputum except in those cases of the streptococcus group which developed an extensive pleural effusion early in the disease. The advent of superimposed hemolytic streptococcus infection of the lower respiratory tract during the course of pneumococcus pneumonia following influenza presented no clinical features that made diagnosis certain without bacteriologic examination. The sudden occurrence of a pleural exudate during the course of the disease seemed of particular significance, especially since empyema in the bronchopneumonias following influenza was exceedingly rare in the absence of hemolytic streptococcus infection. Other suggestive symptoms were a chill during the course of the disease, a sudden turn for the worse in cases apparently doing well, or the development of a cherry red cyanosis. None of these features, however, was sufficiently constant or distinctive of streptococcus invasion to be depended upon and when they occurred, were merely indications for further bacteriologic examination. Bacillus Influenzæ Pneumonia Following Influenza