MANIFESTED IN HUMAN SOCIETY 97 



In comparisons between different countries, the most 

 wealthy and progressive should be the least fertile. 



As a nation becomes more civilised and wealthy the 

 degree of fertility will tend to decline. 



As we ascend the social scale the degree of fertility 

 will steadily diminish with the increase of wealth and 

 prosperity. 



In the fluctuations of a nation's prosperity periods of 

 depression should show an increasing birthrate, whilst 

 periods of prosperity should show a decline. 



These are general rules, from which, owing to the 

 complexity of the factors, we may expect many exceptions. 



It is obviously only through the operation of the law 

 of averages that such a principle can make its action 

 apparent. There are enormous differences between the 

 habits of individuals belonging to the same social class. 

 The degree of fertility is subject to variation between 

 individuals like all other inherited potentialities. Also 

 there appears to be considerable variation in the pene- 

 trating power of the male cells. Thus the factors provide 

 for an enormous range of variation in individual cases. 

 But the law of averages will level up these individual 

 idiosyncrasies, and comparative statistics will show clearly 

 the operation of the principle. 



Demographers have long noticed the general correlation 

 between birthrates and deathrates, and many attempts 

 have been made to explain the connection ; but some 

 writers, in view of the fact the correlation is not uniform, 

 are inclined to deny that there is any real connection. 

 A favourite method of explaining the fact that a falling 

 deathrate is accompanied by a falling birthrate is to 

 reverse the proposition and assert that a falling birthrate 

 is accompanied by a falling deathrate owing to the much 

 smaller infantile mortality in small families. This, how- 



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