108 BIOLOGY OF PNEUMOCOCCUS 



widely from that of the workers at the Rockefeller Institute. In the 

 Transvaal there were a number of additional groups, and Lister's 

 A was of great importance, since its members were more prevalent 

 than those of any of the groups C, B, or E, and caused a higher 

 case fatality. His unclassifiable groups D, F, G, and X Lister con- 

 sidered of less importance, because of the fluctuation in their 

 prevalence and low case mortality. The pneumococci in these 

 groups showed strain-specificity with no cross-reactions in agglu- 

 tination. Lister's A and D Group cultures were placed by Dochez 

 and Gillespie in Group IV. 



Dochez and Avery, 319 in their 1915 paper, explained that pneu- 

 mococci of Groups I, II, and III were found principally in asso- 

 ciation with disease and were distinctly parasitic in type, while 

 Group IV comprised a heterogeneous series of strains, not related 

 antigenically, which caused a minority of cases of pneumonia, and 

 from which the pneumococci occurring in the normal mouth were 

 indistinguishable. Then Avery, 33 by means of agglutination and 

 protection tests, further divided Type (originally Group) II 

 pneumococci into three subgroups, designated by him as "HA," 

 "LIB," and "IIX." Protection tests showed that organisms of any 

 subgroup were not protected against by the serum of other sub- 

 groups, nor did the strains absorb from Type II antipneumococcic 

 serum the specific immune bodies of the other subgroups. Aver}' 

 stated that the organisms of the three subgroups were biologically 

 related to Type II Pneumococcus, that organisms of subgroups 

 HA and IIB were characterized by immunity reactions identical 

 within the respective subgroup, but that subgroup IIX consisted 

 of heterogeneous strains which did not cross with other strains or 

 with Types IIA or IIB. 



In 1916, Olmstead 1027 after testing the agglutinative reaction of 

 over two hundred strains of pneumococci isolated from normal and 

 infected human beings against fifteen serums, including Type I and 

 Type II serums, against which all those strains failed to react, 

 confirmed the validity of the classification of pneumococci into 



