SELECTIVE ELIMINATION 



309 



acquired from their urban compatriots not only tuberculous infection but 

 also tuberculous disease and died off in large numbers." 



"The deaths which occurred in the severe epidemic of influenza in 1918, 

 were to a great extent selective (chart 11). There was a marked increase 

 in the total number of deaths, due for the most part to the complicating 

 pneumonia. But it was also responsible for a large number of deaths in 

 persons afflicted with diseases of the heart and circulatory system. As 

 practically all children are susceptible to influenza (epidemic catarrh) just 



Chart 10. Mortality from Tuberculosis per 100,000 Population at Various Ages 



Dotted line, United States registration area; dashed line, New York City; solid line, 

 Jews of New York City (Jewish Communal Survey, New York, 1928). 



as they are to measles, they must all submit to these tests of their immun- 

 ologic reactions at a comparatively early age especially in large urban 

 centers. These two diseases have therefore an important selective action. 

 An interesting illustration of the difference in susceptibility and resistance 

 in different groups depending on whether or not they have been subjected 

 to selective elimination, is described by Crampton (9). In a vessel sailing 

 from San Francisco several passengers developed influenza on the voyage 

 to the South Sea Islands. The vessel arrived in November 1918, and the 

 passengers were allowed to disembark at Papeete. Within a few days the 



