144 BIOLOGY OF PNEUMOCOCCUS 



addition to normal and degraded R forms, Schiemann postulated 

 intermediate variants which he claimed represented pseudo-types. 

 The discussion was largely theoretical, and since he gave no ex- 

 perimental data, it is impossible to judge the validity of his claims. 



ELECTROPHORETIC POTENTIAL OF VARIANTS 



Falk, Jacobson, and Gussin, 383 and then Falk and Jacobson, 380 

 studied another criterion for variability. The authors measured 

 the electrophoretic potential of Blake's variants A, B, and C from 

 Type I Pneumococcus during cultivation on blood-agar slants, 

 with weekly to bi-weekly transplants, over a period of one and one- 

 half years. The velocities remained constant and paralleled the 

 virulence of the strains. Although the authors believed that elec- 

 trophoretic potential was related in some fundamental manner to 

 virulence, phagocytability, agglutinability, and other serological 

 characters of microorganisms, the particular variants studied 

 were indistinguishable from the parent strain in these characters, 

 and after a large number of generations on blood agar showed no 

 evidence of spontaneous changes. The only exception to this sta- 

 bility of character was a single-cell strain of variant C which re- 

 verted to the A form on passage through a mouse. 



EFFECT OF CHARCOAL, YEAST, OPTOCHIN 



The variation in pneumococci appearing after growth in broth 

 containing animal charcoal or dry yeast and subsequently in opto- 

 chin broth, first observed by Berger and Englemann 100 " 1 and shortly 

 afterward by Morgenroth, Schnitzer, and Berger, 929 was corrobo- 

 rated in 1927 by Amzel. 14 Cultivation in these media gave rise to 

 rough colonies, the members of which were avirulent for mice and 

 exhibited diminished solubility in bile. One strain developed hemo- 

 lytic properties, and another became agglutinable with antiserum 

 for the fixed types. The variations observed after cultivating the 

 cocci in the presence of bile were the same as those occurring in the 

 Schnitzer-Berger medium. 



