Summary
1. Technical improvements are described in the study of apparent peroxide in x-irradiated mice. Hairless mice, 6 weeks old, were fed on peroxide-free food and irradiated with precautions against alarm. Oxygen was excluded during extraction and estimation of peroxide.
2. With radiation doses up to 6000 r the mean ionic yield of apparent peroxide was 28.
3. Without radiation the mean apparent peroxide was raised by alarm and by consumption of normal food which contained peroxide.
4. The mean apparent peroxide did not change significantly between 1 min and 16 hours after irradiation.
5. It was unaffected by a protective dose of AET.