G. S. STENT AND C. R. FUERST 



447 



65°C. a stock of T5st loses 90 per cent of its titer in 5 hours. T5at is inacti- 

 vated by P^- decay at 4°C. with the same specific death rate as the wild type 

 T5. One stock of TSst was grown in H medium containing radioactive phos- 



0.02 0.04 0.06 0.08 

 12 24 12 



0.02 a04 0.06 0.08 1-6" 

 24 12 24 HOURS 



0.02 004 0.06 



0.02 0.04 



0.02 Q04 l-e 



Xi 



Fig. 



lysate, 



2. Inactivation of T5st at different temperatures. Filled circles, radioactive 

 Ao = 300 mc./mg. Open circles, non-radioactive control lysate. 



phorus at specific activity of 300 mc./mg. (at which level 0.1 per cent of all 

 phosphorus is P^-) and one in non-radioactive H medium. After dilution into 

 glycerol-casamino acid medium, aliquots of both lysates were stored at 4, 

 50, 55, 60, and 65°C. and assays of the number of infective centers made from 

 time to time. The result of this experiment is presented in Fig. 2. It is seen 

 that the rate of inactivation of the radioactive lysate is almost the same at 4, 



286 



