THE CAVENDISH LECTURE 



19 



that within sixty years from 1865, namely, in 1925, we shall have 

 reduced the death-rate by nearly 50 per cent, in this country. To 

 this extent modern progress — chiefly medical progress — has sus- 

 pended the actioi) of natural selection. 



175 asa 125 ao9 75. cct- fes o -§5 -so -75 -100 -las -150 -ns 



T^SOBOST. ROBUST SBSSiMLt HS^THT. C^uICATE. 



Fig. 5. — Diagram (1900 odd cases) to explain anomalous position of sons 

 of delicate parents ; a much larger percentage of them die, and thus 

 their health fails to be recorded. The more delicate the father the 

 more children die. 



Does this suspension of natural selection really mean that more 

 of the weaklings survive to propagate their kind ? Some light may 

 be thrown on that point by considering the percentages of the 

 population in 1881 and in 1901 in broad age-groups. 



