268 Discussion 



back to the fact that we must eventually dissect the life-table into 

 several components, as Dr. Benjamin has pointed out, and as H. S. 

 Simms (1940. Science, 91, 7) has shown previously. 



Brauer (personal communication) at the Naval Radiological 

 Defence Laboratory in San Francisco is using McCay's technique 

 now. He re-feeds rats at various ages and finds that the rate of 

 growth when full feeding is re-established carefully is preserved up to 

 quite late ages, and then diminishes. This is somewhat like Comfort's 

 regeneration and re-feeding experiments. Brauer is also examining 

 the effect of previous X-irradiation on the ability to resume growth. 



Rockstein: McCay could accelerate senescence in an old animal 

 which appeared to be young because of starvation. By re-establish- 

 ing the full diet, the animal's appearance rapidly shifted to that of an 

 old animal and mortality was accelerated. 



