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[vol. 59 



; X /o 1- 



10 15 



t Time (rninu-hes) 



Figure 2. The fraction of active particles as a function of the time of illumination (in 

 minutes) and of the interval between infection and exposure to light. Each curve gives the 

 active fraction as a function of the time of illumination (in minutes) for a different interval 

 between infection and exposure to light; the interval is indicated (in minutes) at the right 

 end of each curve. Phage T2r was irradiated for 20 seconds with the germicidal lamp, ad- 

 sorbed on bacteria in broth, and exposed to light in broth at 28 C. 



TABLE 4 



The effect oj the time interval between infection and exposure to light {resting bacteria) 

 Phage T2r, irradiated for 18 seconds with the germicidal lamp, was adsorbed onto resting 

 bacteria suspended in saline. Exposure to light (H-5 lamp with condenser, wave length 365 

 mn) began at various times. Illumination was carried out in liquid. 



various time intervals thereafter and plated in darkness; all plates were incu- 

 bated in darkness. The experiments lasted 140 minutes at most; control experi 



235 



