DISSOCIATION AND TRANSFORMATION 153 



tory. He believed that two methods of inducing degradative dis- 

 sociation in S forms seemed to give rise to the different patterns of 

 variant production. Thus, when S forms were grown in homologous 

 antiserum they became rapidly stabilized as R forms, but when S 

 forms were cultivated in media containing bile, the S organisms 

 displayed a greater tendency to become stabilized as c forms. Paul 

 showed that during the reversion of c, d, and R forms, induced by 

 growth in anti-R or plain rabbit-serum broth, intermediate vari- 

 ants arose in the reverse order to that in which they appeared dur- 

 ing the degradation of S forms. The intermediate variants tended 

 to become stabilized as b forms, which was the usual high level to 

 which these strains reverted by this method. 



A process possibly related to that studied by Blake and Trask 

 was reported by Eaton, 345 an associate of Blake, who described the 

 production of stable strains of Pneumococcus which underwent 

 rapid lysis or failed to grow at 37°. For the strains he introduced 

 the term "phantom colony" or "P-C" variants. This P-C varia- 

 tion, he claimed, was a change independent of the ordinary smooth- 

 to-rough variation. Eaton, moreover, made direct isolation of these 

 variants from cases of human infection. 



Another apparent complication in the symbols employed to iden- 

 tify pneumococcal variants is to be found in the recent papers by 

 Eaton ( 1934-1935 ). 845 " 6 In addition to the phantom colony or 

 P-C variants, he observed smooth variants arising in the daughter- 

 colony dissociation of stock smooth strains after incubation on 

 blood agar at 25°. These smooth variants, called V, and the 

 smooth parent strain, termed N, from which the former were de- 

 rived, had the same virulence for mice and did not differ in anti- 

 genic composition as determined by agglutination, agglutinin- 

 absorption, and mouse protection tests. The smooth V strains were 

 stable, and while they, too, formed daughter colonies they dissoci- 

 ated to rough forms much less readily than did the N or freshly 

 isolated strains. The N and V strains appeared to differ in their 

 capsular staining reactions, and in the ability to form methemo- 



