CHAPTER IV 

 CLASSIFICATION OF PNEUMOCOCCI 



The separation of the members of the species into specific types 

 by immunological reactions, with a description of methods for the 

 determination of these serologically specific types. 



BY tinctorial and cultural methods it is a relatively simple task 

 to differentiate pneumococci from other bacterial species but 

 it is impossible by these methods, except in the case of Type III 

 organisms, to distinguish pneumococci of one serological type 

 from those of another. 



The lance-shaped form, with the presence or development of a 

 capsule, and the appearance of the colonies on blood agar, with 

 their zone of greenish discoloration, are presumptive signs of the 

 identity of these cocci. Solubility in bile, fermentation of inulin, 

 marked pathogenicity for mice and rabbits, and sensitiveness to 

 optochin are all characters which make possible a positive identifi- 

 cation of the species. The possession of these characters has defi- 

 nitely placed the former bile-soluble Streptococcus mucosus among 

 the pneumococci, and its mucoid growth, thick capsule, and greater 

 virulence serve to separate it from pneumococci of some of the 

 other types. However, it is by their serum reactions that the sepa- 

 ration of pneumococci into definite immunological types has been 

 accomplished. 



Serological Classification: 1898-1932 



It was undoubtedly Bezancon and Griffon 108 " 10 who, in 1897, 

 were the first to report a discovery that later was to establish dif- 

 ferences in the serological behavior of pneumococci as a basis for 

 an invaluable aid in all phases of research on Pneumococcus. While 

 Metchnikoff 894 and later Mosny 933 had previously observed the ag- 

 glutinative action of antipneumococcic serum, it was Bezancon and 



