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Raymond Latarjet 



ratios. For example, strains B/r and K12S are equally 

 sensitive both to radiation and to peroxide; B/r is about 6 

 times as resistant as B to peroxide, as it also is to radiation. 



(2) There is no photorestoration after peroxide treatment. 

 On the contrary, Dr. C. C. Brinton observed that under certain 

 conditions doses of light, which are harmless when given 

 alone, may strikingly increase the lethal effect of pretreatment 

 by peroxide. This interesting fact, which will be published, 

 recalls a former observation by Latarjet and Miletic (1953). 



(3) The rate of inactivation very much depends on experi- 

 mental conditions. It rapidly increases with temperature. 

 It decreases when the bacterial concentration increases, 

 soluble organic compounds of the washed suspension and 

 killed cells providing efficient protection to the survivors. 



Inactivation of bacteriophage by peroxide 



Naked phage is very sensitive to peroxide. Inactivation 

 proceeds at a rate which is either exponential or of low 

 multiplicity of hits (Fig. 3). 



(1) Sensitivity of phage may be influenced by its concentra- 

 tion, but this effect may depend on whether or not the phage 

 has been purified. A T2 lysate in 56 synthetic medium 

 containing 5 X 10^^ particles per ml. was dialysed against 

 distilled water, then diluted. Each dilution was treated for 

 15 minutes at 18° by 2 X 10"^ succinic peroxide (Table I). 



Table I 



