174 BIOLOGY OF PNEUMOCOCCUS 



rivanol than were cocci of the original stock. In Modification B, 

 the colonies, made up of A after growing in optochin, resembled 

 those of S. viridans. The cultures contained long chains of round 

 cocci, which were bile-insoluble and were very resistant to the pneu- 

 mococcidal action of optochin. Modification C developed after fur- 

 ther growth on artificial media or in animals, and occasionally 

 after growth in an optochin medium. The C variants corresponded 

 to Streptococcus haemolyticus, they produced more or less he- 

 molysis on blood agar, were bile-insoluble and optochin-fast, but 

 sensitive to rivanol. The progressive changes did not always take 

 place or follow the A-B-C sequence. In twenty-nine experiments 

 with fifteen strains, twenty-two trials produced modifications A 

 and B, and of these strains seven were transformed into modifica- 

 tion C. 



Berger and Englemann 100 continued similar mutation experi- 

 ments and alleged to have demonstrated Modification A in five 

 specimens of sputum and one of pleural exudate obtained from 

 pneumonia patients before the disappearance of fever. The strains 

 were then converted into Modification B by allowing a fairly high 

 concentration of optochin to act upon them. Berger and Engle- 

 mann also claimed that the complete transformation could take 

 place in the human organism. To support the claim the authors de- 

 scribed the development of glistening Type III colonies along with 

 a few strongly hemolytic streptococcal colonies on a blood-agar 

 plate upon which pneumonic sputum had been spread. The organ- 

 ism, after the first mouse passage and three culture generations, 

 developed into a green streptococcus ; after a second direct mouse 

 passage both pneumococci and hemolytic streptococci appeared, 

 the latter partly reverting to Pneumococcus after two culture gen- 

 erations. The original hemolytic streptococci after three culture 

 generations became green streptococci and after four culture gen- 

 erations reverted to pneumococci. This cycle, like Rosenow's, seems 

 almost too rapid and direct to be credible. 



In another communication, Berger and Jakob (1925) 102 returned 



