It had, on the contrary, significant effects bination with irradiation (300 R). on specific spontaneous or radiation-induced diseases, since it reduced the incidence of lymphosarcoma and pituitary, harderian and adrenocortical adenoma and it increased the incidence of lung adenoma. For two other diseases, septic metritis and severe glomerulosclerosis, castration interacted with radiation in nullifying their increased incidences brought about by radiation. Although not strictly comparable, these findings seem at variance with those of Hamilton et al. [H14] who exposed LAF1 mice to 145 R/day and found that females had a grea- ter sensitivity than males, judging on survival time. However, when the females were ovariectomized their survival came nearer, although still lower, to that of the males. Thus, acute survival might be influenced by ovariectomy, as opposed to long-term survival. D. PARTIAL-BODY IRRADIATION 1. 314. Mouse Although selective partial-body exposure might be in principle a good methodology to study the pathogenesis of the individual causes of death responsible for life-span-shortening, data on this subject are comparatively few. the mouse Kallman and Kohn [K7] reported on CAF1 250 KVp x rays. In females exposed acutely to Partial-body irradiation was performed bilaterally on the tho- rax (weight of irradiated tissues about 7.6 g); on the right hemithorax (3.5 g) and on the pelvis 95.0g). Three hundred and 500 R given to the whole-body pro- duced an appreciable shortening of life. Partial-body exposure on the chest or on the pelvis was much less effective than whole-body irradiation in terms of tissue dose units. The smallest whole-body doses were more effective than the larger per unit dose but the reverse was true in the case of partial-body exposure. In the partial-body exposure of one region the loss of life per unit absorbed dose (dose per unit volume of tissue) was not a constant in these experiments. 315. Boone [B8, B9] worked on mice of the same strain and sex irradiated on the whole-, lower- or upper-body with x-radiation in single doses. Whole-body irradiated animals (150 mice for each group) received 100, 200 or 400 rad, shielded animals 200, 400 or 800 rad and shielding was adjusted in order that the total weight of the tissues included in the irradiation fields would be the