168 THE TREND OF THE RACE 
during their lives. Still higher estimates are made by Lenz, 
although they are based on very unreliable methods. In Den- 
mark (1886-95) venereal infection in Copenhagen, other cities 
and in the country bore the ratio of 201, 30, and 4 respectively 
(Prinzing.) 
It is impossible on the basis of any statistics that have been 
compiled to ascertain whether venereal diseases have been in- 
creasing or decreasing. Medical opinion on the subject is very 
divergent. It is only recently possible, owing to the discovery 
of the Wassermann and other tests for syphilis, to gain any 
idea as to the extent to which this scourge is disseminated 
among the population, and no data have yet been compiled that 
will give an accurate idea of its prevalence. We are much less 
able to estimate its prevalence in times past. 
Since venereal diseases are much more common in cities, and 
since the city population has been increasing at a relatively rapid 
rate, it would seem likely that venereal diseases in cities have been 
on the increase. And if they have increased in the cities it would 
be only natural that with our greatly increased means of travel 
they would be disseminated into the small towns and rural 
districts, leading to an increase also in these communities. We 
are perhaps justified in attributing the tendency of the birth 
rate to fall more rapidly in the cities in part to the greater preva- 
lence of venereal disease in urban communities. But how far 
these diseases have produced a fall of the general birth rate is 
uncertain. 
Of all the factors influencing the birth rate, it is probable that 
the most potent is the voluntary restriction of births. In many 
families children do not come because they are not wanted, and 
in many others the number of children is limited to two or three. 
The custom of standardizing the family, so common in France, is 
rapidly spreading to other lands, especially among the members 
of the higher social strata. Large families are no longer in style, 
and parents who have many children are often regarded as 
guilty of a violation of good form, if they do not incur a more 
serious judgment. 
