122 



OXIDATION-REDUCTION POTENTIALS 



When the appropriate bacteriophage was added to cultures of B. dyseMerics 

 (Shiga) no proliferation of the bacteria was observed and there was no fall in potential. 

 Addition of bacteriophage to cultures after proliferation had occurred had little effect 

 except to inhibit any appreciable further fall in potential. {See fig. 33.) In the case 

 of B. coli communis, the addition of the bacteriophage delayed proliferation of the 

 bacteria and also delayed the fall in potential but did not affect the ultimate growth 



o 



W 



6 12 18 



Time (hours) 



Fig. 33 



Aerated broth cultures of B. dysenlerice (Shiga) 



Time (hours) 



Fig. 34 



Aerobic glucose broth cultures of B. coli communis 



or potential of the culture. In the case of aerobic glucose cultures the potential fell 

 initially even in the presence of bacteriophage despite the absence of visible growth 

 in these early stages. After this early fall the potential rose and did not fall again 

 until visible growth of the culture was noticeable. {See fig. 34.) The initial fall 

 in potential was, perhaps, due to activation of the glucose by the non-proliferating 

 bacteria inoculated into the medium. Rather similar phenomena were observed in 

 the case of Staphylococcus aureus. This last observation has been confirmed, in a 

 personal communication, by Dr. Clifton of Stanford University, CaUfornia. 



