46 



Dr. J. A. Murray. Cancerous 



[Mar. 22, 



it because of the early death of their female parents and grandparents, 

 tumour mice would he transferred from the non-cancerous group to that with 



30 mont/is 



over 2*4 



Fig. 1. — Percentage of deaths from mammary carcinoma to deaths from all causes at 

 successive three-monthly age-periods in female mice of recently cancerous ancestry 

 (mother, grandmothers) , compared with the same ratio in female mice having 



more remote cancerous ancestry (mother and grandmothers non-cancerous) - ---- 



over 26" 



Fig. 2. — The same comparison as in fig. 1, with different limits to the three-monthly 

 age-periods (second period, four months). As in fig. 1, the frequency of the deaths 

 from cancer in the cancerous group exceeds that of the non-cancerous group at all 

 periods except the last. 



