EVOLUTION MADE PLAIN 51 
past is sympathy, mercy. This bars him from 
using Nature’s method of preventing undesir¬ 
able offspring; nor can he use the sterilization 
method except in extreme cases. Born crim¬ 
inals, perverts, and other abnormal misfits who 
persist in indulging their selfish passions in 
detriment of the Common Good—for such, com¬ 
prising perhaps 5 to 10 per cent of the race, 
sterilization is the quickest and surest preven¬ 
tive. Once the milder type of defectives are 
made to realize the heinous crime of bringing 
degenerate children into the world they would 
in most cases refrain from marriage and procre¬ 
ation. Wise restrictive laws and an awakened 
public opinion would do the rest. This eugen- 
ical system is the only one that promises hope 
for the salvation of the race. From generation 
to generation, owing to the fecundity of the 
less fit and their proneness to “let Nature take 
her course,” their numbers increase, and so, 
too, the danger increases of their swamping 
the fitter. 
* * * 
From the exposition of natural selection it 
will be seen that all the laws of organic de¬ 
velopment—either of individuals, varieties or 
species—fall under two heads: those of hered¬ 
ity (the harking back to ancestral characters) 
and those of environment (all outside influ¬ 
ences). Variation, which seems so contradic¬ 
tory of the law of “like producing like,” is in 
reality a result of heredity. Offspring inherit 
traits, more or less repressive in one or both 
parents, in different degrees—this is variation. 
The gist of the matter is: heredity transmits 
