140 THE TREND OF THE RACE 
cause they may produce great havoc before they are detected, ot 
at least before the extent of their damage is adequately realized. 
3. The elements of the population that are of subnormal 
mentality exhibit at present the highest degree of fecundity. This 
is the general verdict of most students of the birth rate of different 
classes of the population. The higher death rate of the subnor- 
mals probably does not offset completely their greater fecundity. 
There are various factors, however, which tend to reduce the 
fecundity of subnormal classes. Criminals have their families 
reduced on account of penal servitude, and it is improbable that 
tramps and hoboes, who as a class are of subnormal mentality, 
leave sufficient offspring to replenish their stock. Prostitutes, 
who constitute another subnormal class, are frequently sterile as a 
result of venereal diseases, and they also purposely avoid having 
offspring. We possess little data concerning the fecundity of 
women of this calling. Many of them have had one or more 
children before entering upon their professional career, and 
they sometimes marry and bear children after the business of 
prostitution has been abandoned. Although they come from 
stocks that are more than usually prolific, it is very doubtful if 
they produce sufficient offspring to replace themselves. 
The subnormal elements of the population thus suffer in several 
ways an extensive sterilization of their number. We have no 
means of accurately measuring the extent of the losses to their 
ranks. Notwithstanding crime, vagabondage, prostitution and 
a high infant mortality, stocks like the Kallikaks, Jukes, Nams, 
etc., somehow continue to increase in numbers. If their produc- 
tiveness suffers from crime and vice, the celibate careers, late 
marriages and restricted birth rate of the classes in the higher 
social strata apparently reduce fecundity still more. At any rate, 
the latter classes in general have a birth rate which cannot fail to 
lead to extinction. This much is clearly indicated from a variety 
of sources, while the springs of our defective inheritance have 
shown no manifest signs of drying up. 
