240 HEREDITY AND EUGENICS 



ditions can affect this ratio, 3^et it undoubtedly appears 

 to be the case that in some wa}^ the ratio of male to 

 female births is increased, so closely is the biological 

 status of the race amenable to economic conditions 

 like war or an epidemic. Emigration also leaves a 

 vacant space which is soon filled up by an increased 

 birth-rate, but as Carr-Saunders points out, the 

 importance of emigration in this respect has been 

 greatly overrated. 



The nineteenth century was a period of rapid 

 increase in population, both in Europe and America, 

 but the birth-rate in Europe and in the Anglo-Saxon 

 population of America has been falling throughout 

 the last quarter of that century and the subsequent 

 two decades, though there may be a temporary rise 

 following the war. Of course, a permanent fall in 

 the birth-rate must ultimately take place when the 

 relatively empty countries available to the white race 

 have been filled up. The serious feature of the 

 declining birth-rate is its differential character, for 

 birth control, as practised, leads to a condition in 

 which we are breeding most largel}^ from our worst 

 stocks. Eugenists are agreed that the greatest need 

 is for some method of adjusting conditions, so as to 

 remove this menace to the future of the race. 



The Problems of Population. 



Problems of population have been discussed ever 

 since Malthus formulated his law that population 

 tends to increase in geometrical ratio, while the means 

 of living — food and raiment based on agriculture — 

 only increase in arithmetical ratio, thus leading to 

 human poverty, misery, and vice. The accuracy of 

 this law has often been affirmed and as often denied. 

 The fact that it led both Darwin and Wallace inde- 

 pendentl}' to the conception of natural selection 



