The following is a summary of the observations which were made during the course of the present investigation. (I) Isolation and identification of the pneumococcus A. The intraperitoneal inoculation of mice proved an excellent method of obtaining pneumococci in sufficient quantity for purposes of identification. B. The sodium taurocholate solution gave good results in most cases, but two strains of Type I. organisms were met with which were insoluble in the taurocholate solution. C. The microscopic agglutination test which was carried out in conjunction with the macroscopic test was found to give results which were in perfect agreement with the results obtained by the older method. (II) Incidence of the serological types. The percentage incidence of the different types is shown in Table III. Prom Tables IV. and VI. it will be seen that in the age group 16 to 60 the greatest number of cases were due to Type II organisms, while in the 1 to 15 age group the greatest number were due to Type I organisms. (III) Clinical Investigation of the cases. A. In the clinical examination of the cases there was no evidence that any train of symptoms existed by which one type could be distinguished from another. Certain minor differences did however exist between the various types. In Type I. cases the onset of the condition was more often associated with shivering. The temperatures in these cases tended to run at a slightly higher level and were less liable to remissions than in the other types. In Group IV. cases, more especially among the adults there was a greater percentage of cases giving a history of previous respiratory disease. B. In the present series of cases, blood stained sputa were met with in 63% of the cases. Among the adults 80% had blood stained sputa, and of this number 67.9% were met with in cases due to the fixed types, and 12.3% in Group IV. cases. Between the fixed types there was a slightly greater incidence in Type II. than in Type I. C. Complications. The number of cases which developed complications was relatively small. Of the four cases manlfesting involvement of the nervous system 50% were due to Group IV organisms. (IV) Mortality The mortality rate in the present series was only 9%. This is in contrast to the high death rate of 50% in cases due to Type III. pneumococci. (V) Lung puncture Lung puncture affords an accurate means of obtaining the organism in cases where sputum is not available. In one case, the type of pneumococcus isolated from the lung Juice differed from that isolated from the sputum. (VI) Significance of a bacteraemia in lobar pneumonia The presence of a bacteraemia in cases of lobar pneumonia, as estimated by finding the pneumococcus in 2 c. cs of blood, is of grave significance. In the present series 60% of the cases with a bacteraemia terminated fatally