348 THE TREND OF THE RACE 
cian Von Mayr, is of outside origin. But until more is known of 
the relative fertility of those born in the city and those who come 
in from the country it cannot be ascertained to what extent the 
populations of cities are really self-sustaining. As stated pre- 
viously the population of Paris and that of Berlin is not reproduc- 
ing itself. The remarkably low birth rate of several cities of 
Switzerland renders it probable that the same conclusion holds 
for them also. Ballod has attempted to show, on the basis of 
studies on the average duration of life in Germany, that in several 
large cities the population would show a small deficit were it not 
for the influx of people from the outside who help to swell their 
birth rate. The same conclusion is drawn for ten of the most 
urban districts of France. Estimates of the real natural increase 
of cities present many difficulties and in most cases data are not 
available for a separate estimate of the births of the native and 
the immigrant elements of the city population. Ballod’s calcula- 
tions were based on statistics compiled in the last two decades of 
the 19th century, since when there has been a considerable 
decline in urban birth rates. Death rates have also declined so 
that comparisons with present day conditions cannot be made 
without an extensive reinvestigation. We are reasonably safe in 
saying, however, that several cities would not sustain themselves 
at the present time if it were not for immigration from the outside. 
The rapid fall of ‘the urban birth rate has affected most the 
classes upon whose intelligence, initiative and energy the rank of 
a people mainly depends. It is a very difficult task to estimate 
the eugenic worth of city immigrants as compared with that of 
the native city born; data on the subject as well as opinions are 
conflicting. With more accurate and extensive demographical 
bookkeeping this important question could doubtless be def- 
initely settled. But however the stream of urban migration 
compares with the rest of the race, the process of diminishing the 
capable and enterprising elements of the community is appar- 
ently intensified in cities, and especially large cities. 
One important consequence of the development of modern 
industry is the increasing employment of woman and the growing 
