Longevity 



183 



The diagram for illustrating this table 

 shows that the longevity of children increases 

 as the age of the father increases up to the age 

 of 29 for the father, that it then remains 

 practically stationary for all surviving chil- 

 dren born during the next ten years, and that 

 from that date it increases rapidly as the age 

 of the father increases. Taking the entire 

 diagram it may be said that each four years 

 added to the age of the father adds approxi- 

 mately one year to the natural longevity of 

 the child. 



COMPARATIVE LONGEVITY OF BROTHERS 

 AND SISTERS. 1105 CASES. 



The effect of the age of the father on the 

 normal longevity may be looked at in another 



