SENSITIZATION BY OXYGEN 



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period, and later most of them can be easily revived. Mice asphyxiated 

 by nitrogen or carbon dioxide received soft x-rays (0.8 A), at a dose of 

 1500 r, on the whole body. Whereas the normally irradiated controls 

 all died within 12 days, the animals irradiated during anoxia not only 

 all survived, but subsequently grew at the same rate as the non-irradiated 



Fig. 6. Effects of anoxic irradiation on newborn mice. Right to left: 1, Non-irradiated 

 control; 2, irradiated in anoxia; 3 and 4, normally irradiated. 



controls. With ultraviolet rays the difference between normal and 

 oxygen-deprived animals was as notable as with x-rays, with reference 

 both to cutaneous lesions (erythema, epidermitis, deep burns) and to 

 general toxic effects (delay in growth, death). Figure 6 shows, starting 

 at the right, a non-irradiated control, an animal irradiated in anoxia 

 (similar in all respects to the control), and two animals normally exposed 

 to the same dose. The last two show severe cutaneous lesions and dis- 

 tortion due to deep edema. The animal at the left died. 



The same influence of oxygen is found at the other end of the organic 

 scale, in a simple radiochemical reaction such as formation of hydrogen 

 peroxide in water irradiated with x-rays or alpha rays. The primary 



