Onset of Disease and Longevity of Rat and Man 75 



AGE 



100 200 

 IN DAYS 



300 400 500 600 



700 



800 900 1000 1100 



Fig. 3. Age distribution of onset of rat lesions. These 



curves show the probabihty of onset at various ages 



(among the total number living at each age) (From 



Simms and Berg, 1957). 



its greatest probability of onset at 750 days of age, although a 

 few rats acquired lesions at 500 days — and some not until 

 1,000 days. Similarly, the peak for chronic nephrosis and 

 glomerulonephritis was 580 days and the peak for periarteritis 

 was 710 days. 



300 200 



AGE IN DAYS 



900 1000 



Fig. 4. Probability of onset of new lesions among the 



surviving rats having no lesions (From Simms and 



Berg, 1957). 



