226 ENVIRONMENT 



tained very largely by new-comers : more than 

 a third have their birthplace elsewhere. But it 

 is difficult to establish a connection between 

 fertility and immigration : indeed we find the 

 highest birth-rates in districts of East London 

 where the immigrant population is comparatively 

 small. And, taking England as a whole, urban 

 life does not appear to be prejudicial to fertility. 

 The average birth-rate is actually lowered if we 

 exclude the 100 largest towns from our calcula- 

 tions. 



It may be that the very high infantile death- 

 rate amongst the poorest classes of our towns 

 results from a form of infertility which denies 

 length of life to offspring although it may per- 

 mit them to be engendered. But this is only a 

 surmise ; and, generally, if we understand by 

 fertility reproductive capacity, there is little 

 to show that it is affected by surroundings that, 

 in fact, the English birth-rate would not rke very 

 greatly if celibacy fell into disrepute, child- 

 bearing became fashionable, and marriage was not 

 so long delayed after the attainment of the age of 

 puberty. 



:jfiJ;|lt 



If the physical features and characters of the 

 races of mankind are derived very largely from 

 environal influences we should expect to find them 

 modified where these influences are changed. 

 We have seen that this has very often occurred 

 even within the period of history. English fami- 

 lies lose their vigour in tropical countries : a like 

 change was suffered by the northern peoples who, 

 band after band, fought their way to the shores 

 of the Mediterranean, by the Aryan, Scythian, 

 and Tartar invaders of India, by the Arabs who 

 left their deserts for the amenities of Syria, North 



