346 



HEREDITY AND SELECTION IN SOCIOLOGY 



ceming phthisis as typical of those concerning tuberculosis as 

 a whole. Let us now look at these statistics : 



These figures teach us the same lesson as those previously 

 given concerning the rate of mortality in general at different ages. 

 Those persons most effectively protected from the results of 

 tuberculosis — or, rather, those tuberculous persons who have 

 most greatly benefited by modern hygiene — are precisely those 

 under twenty years of age. Even in the short space of time 

 under consideration the rate of juvenile mortality from tuber- 

 culosis has sunk from 445 per million to 350 per milUon, in the 

 case of children under five ; from 239 per million to 184 per 

 million for children from ten to fifteen ; and from 1,018 per 

 million to 876 per million for young persons between fifteen and 

 twenty. On the other hand, the rate of mortality for persons of 

 forty-five and upwards has increased from 3,230 to 3,440 per 

 million, and that of persons of fifty-five and upwards from 2,703 

 to 2,838 per million. 



Thus, the net result of our modern hygienic precautions as 

 regards tuberculosis has been this : the weak and predisposed 

 children have been preserved in larger numbers, their life has 



