INFLUENCE OF INDUSTRIAL DEVELOPMENT 347 
There is no doubt that the opinions expressed by Hansen and 
Ammon have been widely influential in Germany and have 
stimulated interest in the agrarian policies carried out in that 
country. Militaristic writers,—and we must count Hansen and 
Ammon among them,—have viewed with much concern the 
relatively poor showing which cities have made according to 
recruiting statistics and the records of urban birth rates. In 
numerous German discussions of the subject that appeared before 
the Great War we find frequent allusion to the ‘“‘Wehrkraft” or 
“Wehrfahigkeit,” which it was feared might not retain its relative 
superiority in face of the portentous fecundity of the Slavic 
neighbors of the empire. The situation which has called forth so 
many lamentations from Germany obtains to almost as great 
an extent in most other civilized countries, although its military 
aspect has caused much less uneasiness. The questions raised by 
Hansen and his followers are of the most serious consequence to 
mankind in general, and it should constitute a part of the program 
of institutions dealing extensively with vital statistics to collect 
the data required for their solution. 
The views of Hansen, Ammon and their followers have elicited 
a great deal of adverse criticism on a number of points. The fact 
urged by Kuczynsky that cities often have a fairly high birth 
rate and a death rate lower than that of the country is by no 
means a proof that cities are self-perpetuating. Weber cites as 
a fatal objection to Hansen’s theory the circumstance that in 
Germany ‘‘in several years the ratio of births to deaths has been 
larger in the great cities than in the Empire as a whole, and in 
recent years the two ratios have been about the same.” It is, 
however, only an apparent paradox to say that a surplus of births 
over deaths does not indicate that city populations are self-per- 
petuating. The immigration of people from 20-40 years of age 
reduces the death rate and tends to increase the birth rate. How 
much of the urban increase is due to the fecundity of immigrants 
from the country is not known. A very considerable part of the 
population of cities, and a larger proportion of the population of 
large cities, according to the principle announced by the statisti- 
