286 



A. C. UPTON, M. A. KASTENBAUM, AND J. W. CONKLIN 



upward by irradiation (Figs. 1-4) and by radiomimetic chemicals (Fig. 4). 

 The displacement by radiation was, furthermore, dose-dependent and evident 



25 50 75 100 125 



1 irne after exposure (weeks) 



Fig. 1. Mortality rate of LAF^ male mice in relation to time after y-irradiation. (Mice were 

 irradiated at 6 to 12 weeks of age.) (Modified from Upton et al., 1960.) 



O Non-irradiated controls (306 mice); D 223 rads (210 mice); • 368 rads (316 mice); 

 A 578 rads (306 mice); J^ 679 rads (270 mice). 



100 



50 75 100 125 



Time after exposure (weeks) 



75 



Fig. 2. Mortality rate of LAFj female mice in relation to time after y-irradiation. (Mice 

 were irradiated at 6 to 12 weeks of age.) (Modified from Upton et al., 1960.) 



O Non-irradiated controls (308 mice); D 223 rads (212 mice); • 368 rads (290 mice); 

 A 578 rads (298 mice); 4 697 rads (266 mice). 



