452 



RADIATION INJURY AND LETHALITY 



described above (37), but for our present purposes we will use a simpler 

 and more restricted development which permits us to make use of the 



250 



100 150 200 



Mean dose rate, r/day 



250 



Fig. 5. Relation between mean survival time and dose rate for two strains of mice. 



Open circles: ABC males, mean after-survival of controls, 540 days; solid circles: 



CF-1 females, mean after-survival of controls, 450 days. 



many studies carried out on small groups of animals, for which the ac- 

 tuarial methods are not suited. 



In this alternative approach, which we call the kinematic method 

 (33) , the behavior of a population is described by a single representative 



5000 



S 4000 - 



^ 3000 - 



2000 - 



15 1000 - 



50 100 

 Mean dose rate, 



1000 



Fig. 6. Relation between mean accumulated dose and logarithm of dose rate for 



ABC male mice. The function has a shallow minimum in the neighborhood of 



90 r/day, rises to a maximum in the neighborhood of 15 r/day, and then decreases 



to zero as dose rate decreases further (not shown here). 



