THE CAVENDISH LECTURE 



17 



fertility of the fitter stocks and we have the state of affairs — the 

 very grave state of affairs — which we of to-day are called upon to 

 meet. 



Now you will say, and rightly say, that each stage of this argu- 

 ment needs to be supported by very solid facts. Well, as far as 



GENSRAL HEALTH. 



175 150 135 100 

 V- ROBUST 



50 25 -H5 -50 -75 -100 -125 -150 -175 

 ROBUST NORMALLY HEALTHY DELICATK 

 FATHER 



Fig. 3. — Diagram illustrating fall in health of son with fall in health of 

 father. Note anomalous position of sons of delicate fathers. In these 

 diagrams lOO units of health correspond to the normally healthy group. 



is consistent with the time available let me give you illustrations 

 of what I mean. 



In the first place, I hope you will agree with me when I say 

 that the general death-rate is selective. Secondly, the progress 

 of medical and sanitary science has altered the stringency of selec- 



