One hundred and eleven consecutive cases in which careful clinical and bacteriologic studies were made form the basis of the material presented. Of these cases, 38 came to necropsy so that ample opportunity was presented to correlate the clinical and bacteriologic studies made during life with the pathology and bacteriology at necropsy. It has seemed advisable to group the cases primarily on an etiologic basis with secondary division according to clinical features in so far as this can be done. Bacteriologic studies showed that at the time of onset these pneumonias were either pneumococcus pneumonias or mixed pneumococcus and influenza bacillus pneumonias in nearly all instances. Certain of these cases later became complicated by a superimposed hemolytic streptococcus or a staphylococcus infection. In a few instances hemolytic streptococcus pneumonia directly followed influenza without an intervening pneumococcus infection. B. influenzæ was present in varying numbers in nearly all cases. In only 2 instances however, was it found unassociated with pneumococci or hemolytic streptococci, once alone and once with S. viridans. Clinically the cases fell into four main groups: (1) Lobar pneumonia; (2) lobar pneumonia with purulent bronchitis; (3) bronchopneumonia (pneumococcus); (4) bronchopneumonia (streptococcus). It should be borne in mind, however, that the picture was a complex one and that correct clinical interpretation was not always possible, since many cases did not conform sharply to any one type and superimposed infections during the course of the disease often modified the picture. =Pneumococcus Pneumonia Following Influenza.=—Bacteriologic examination of selected and washed specimens of sputum coughed from the lungs at time of onset of pneumonia showed the various immunologic types of pneumococcus to be present in 105 cases. The incidence of the different types is shown in Table XIV. TABLE XIV TYPES OF PNEUMOCOCCUS IN 105 CASES OF PNEUMOCOCCUS PNEUMONIA FOLLOWING INFLUENZA ═══════════════════════╤═════════╤═════════════════╤═════════╤═════════ │ LOBAR │BRONCHOPNEUMONIA │ TOTAL │PER CENT │PNEUMONIA│ │ │ ───────────────────────┼─────────┼─────────────────┼─────────┼───────── Pneumococcus, Type I │ 8│ 0│ 8│ 7.6 Pneumococcus, Type II │ 3│ 1│ 4│ 3.8 Pneumococcus, II atyp. │ 12│ 7│ 9│ 18.1 Pneumococcus, Type III │ 3│ 3│ 6│ 5.7 Pneumococcus, Group IV │ 32│ 36│ 68│ 64.8 ───────────────────────┴─────────┴─────────────────┴─────────┴─────────