DISSOCIATION AND TRANSFORMATION 143 



inulin fermentation. When either of these properties was lost the 

 other disappeared. 



Takami 1375 followed the in vitro experiments with a study of the 

 variations displayed by pneumococci propagated in the animal 

 body. Rabbits, guinea pigs, mice, white rats, and house rats were 

 used for this purpose, and the variants produced in these animals 

 differed in agglutinative characters from the forms developed on 

 artificial media. The explanation offered was that in the body the 

 organisms lose their old receptors and acquire new ones. Takami 

 separated five typical strains of "culture-bacteria" (pneumococci 

 long grown on blood agar) into colonies that were still markedly 

 agglutinable, and into others that had lost this power. The latter 

 were found to be highly virulent for mice, whereas the former were 

 avirulent. 



A few years later, Kimura, Sukneff, and Meyer 711 repeated the 

 dissociation experiments, using broth containing 10 per cent ho- 

 mologous immune serum, with subsequent cultivation of the vari- 

 ants on Griffith's chloroform-blood agar and Bieling's blood-water 

 agar, both of which have a laked-blood base. The results were simi- 

 lar to those reported earlier, but the authors believed that they 

 had demonstrated the production of other variants in addition to 

 the atypical R forms with divergent cultural and serological char- 

 acters. The experimental data, however, are insufficient for judg- 

 ing the claim. 



For determining the true character of normal strains and of dis- 

 sociants, Schiemann 1225 adopted as a criterion the possession of a 

 type-specific (dominant) hapten as a prerequisite for the forma- 

 tion of type-specific agglutinins and protective antibodies and also 

 for virulence. For the recognition of type-specificity the essential 

 considerations were, first, coarse agglutination in homologous anti- 

 serum determined by the carbohydrate nature of the hapten ; sec- 

 ond, the repression of cross-agglutination in heterologous serum ; 

 and, third, mouse virulence. According to these standards, in 



