DNA AND Effects of Radiation and Peroxides 281 



In the dialysed lysate, sensitivity is independent of concen- 

 tration below 10^; but in the normal sample, it steadily 

 increases with dilution, and becomes much greater than in the 

 purified lysate. This fact (and others which we encountered in 



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MINUTES of CONTACT 

 Fig. 3. Inactivation of phage T? by succinic peracid. 



other types of experiments) shows that toxicity of peroxide 

 may increase in the presence of some organic substances. We 

 believe that when oxygen is present these substances can be 

 peroxidized by chain reactions, thus increasing the titre of 

 peroxide groups. This point should be studied, for example by 

 removing oxygen before peroxide treatment. One should 



