CLASSIFICATION OF PNEUMOCOCCI 113 



attributed these variations in normal specificity, such as marked 

 decrease in agglutinability with homologous serum and the ap- 

 pearance of agglutinability with heterologous serum, to serological 

 modification brought about by growth of the organisms on unfa- 

 vorable media. 



Takami (1925) 1373 ' 1375 had even less success in efforts to classify 

 Japanese strains according to the American scheme, and said that 

 all such attempts had completely failed in Japan. It seems highly 

 improbable that specific types of pneumococci are not to be found 

 in that country. The various modifications which the American 

 strains underwent on artificial media may explain the unusual re- 

 sults. Takami offered this fact as an explanation when he con- 

 cluded that "for serological grouping of pneumococci one must 

 work only with strains which have become virulent through animal 

 passage, or strains which have been cultivated directly from the 

 human body and have not undergone variation on artificial me- 

 diums." Megrail and Ecker, 888 on the contrary, presented definite 

 evidence that Pneumococcus possesses a type stability under con- 

 ditions in which typhoid bacilli and other organisms show vari- 

 ability in agglutination. The reliability of the methods for the 

 serological typing of pneumococci is further supported by the re- 

 sults of Christensen 229 and of Griffith, 558 who demonstrated the 

 complete specificity of the mouse-protection test. 



In 1929, Cooper, with Edwards and Rosenstein, 272 tested 120 

 strains of pneumococci isolated from cases of lobar pneumonia 

 that either did not agglutinate or else reacted atypically with di- 

 agnostic antiserums for Type I, II, and III pneumococci. These 

 authors included Avery's IIA and IIB strains, representatives of 

 various types from Pittsburgh, and the atypical III strain de- 

 scribed by Sugg, Gaspari, Fleming, and Neill. 1354 Cooper and her 

 associates prepared monovalent serums from rabbits and horses, 

 and with serum divided the 120 strains into ten groups containing 

 four or more strains each, and a miscellaneous group comprising 



