106 



HOLLAENDER, StAPLETON AND BURNETT 



contrast to this, the sigmoid shape of the anaerobically grown 

 and irradiated organism is quite well established. 



Tests were conducted to determine if compounds of the 

 different groups were additive in their protective action. We 

 have already mentioned that BAL and cysteine, given at 



T" 

 10' 10' lO'' 



MOLAR CONCENTRATION FORMATE 



10 



Fig. 8. Survival of E. coli in different concentrations of sodium 



formate after incubation at 37"C. for 30 minutes. Stapleton, 



Billen and Hollaender (1951). 



concentration at plateau level, would not supplement each 

 other in protective ability. In contrast to this, combinations 

 such as alcohol and BAL, sodium hydrosulphite and BAL, 

 and ethanol and hydrosulphite do give additive protection, 

 as indicated in Fig. 9. However, when all three types of 

 compounds were used simultaneously, we did not get signifi- 

 cantly more protection than from two types. It is possible 



