VET Torrie s ahheanalirmntherdncrde TTT TTT aul Leb tt tical oh. Lisatl : Led tt tatat GOMPERTZ SLOPE FOR ALL CAUSES EXCEPT RETICULAR TUMOURS 10; DAILY DOSE. R/DAY Figure VIIl. A plot of life-shortening to daily dose for mice treated with life-time gamma rays exposure. Life-shortening its measured by the increase of slope of the Gompertz function in irradiated as compared to control populations. Open circles refer to BCF1 and closed circles to LAF1 mice. The dashed line corresponds to the inferred relationship for single exposures with constant effectiveness per roentgen of 0.003 R~. 2. 12h, Data from Sacher [81h]. Guinea-pig One hundred-day old male and female guinea-pig were started on a frac- tionated course of radiation (o6 gamma rays) for the entire duration of life [R2]. Together with a number of control animals, groups receiving 1.35 R, once or four times a week; 2.6 R, 5 times a week; 6.0 R, 4 times a week; 24 R, once a week; 6 R, 6 times a week; were included for a total of 344 animals. The relationship of the log mean after-survival time against the weekly ex- posure in R was approximately linear and the life-shortening coefficient came to about 0.06 days/R, in close agreement with the data of Lorenz et al. [16]. At 5.4 R/week a paradoxical early decrease of mortality was noted in males for which no explanation could be given. Fatty degeneration of the liver, chro- nic kidney diseases, spleen amyloidosis and various tumours were noted in the animals in no obvious correlation with 1ife-span-shortening.