cold treatment. Other effects were also not modified, except perhaps for a slight reduction of the accelerated tumour onset seen in whole-—body-irradiated animais. Interpretation of these data is made difficult by the fact that the cold treatment per se has produced life-span reduction and changed the spectrum of diseases with a prevalence of inflammatory pulmonary conditions and a relative decrease of neoplasia [H111!. 297. Some information is also available in regard to the modifying effects of a specific stress on long-term mortality of irradiated animals. Ordy et al. [01] irradiated C57BL/10 mice on the brain with 500 rad of 20 MeV deuteron beam with a highly significant decrease in longevity of the irradiated animals. They also observed a reduction of the late mortality in the animals undergoing periods of daily stress (cold, electrical shock, or both). Such an effect appeared to be statistically significant in some, although not all, groups of animals and was observed irrespective of whether they had been irradiated or not. 298. Reincke et al. [R9] submitted Wistar rats at 120 days of age to star- vation for 9 days, water deprivation for 6 days or forced swimming. Animals that had passed through such severe stress before irradiation (280 R of x rays, single dose), lived longer than those receiving irradiation only. The differ- ences in the survival curves were significantly different in three out of six possible comparisons. No influence of stress was observed on the tumour incidence. B. PHYSICO-CHEMICAL AND PHARMACOLOGICAL TREATMENTS 1. 299. mined. Anaesthesia, oxygen and hypothermia The effects of hypoxia induced by various treatments will first be exaLindop and Rotblatt [L12] showed some protective action of anaesthesia (Nembutal, 60 mg/kg, i.p.) against early and late death. Protection appeared to decrease with dose-rate in the interval 480-162 000 rad/min. Protection could not be ascribed to low oxygen tension in tissues by the anaesthesic drug, because there was no summation of effects by the anaesthesia and dose-rate, particularly at the high dose rates. In other series of experiments Lindop and Rotblatt [L12, L16] showed that when SAS/4 mice, anaesthetized with 20-60 mg/kg of Nembutal and breathing nitrogen 30-50 second, were exposed to a beam of fast