40 HEREDITY AND SOCIETY 



otherwise, have, as their one weakness, a special pre- 

 disposition to that particular disease. Now, useful as 

 immunity from a microbic disease may be in our 

 present imperfect world, it is not the highest ideal for 

 mankind. If we can banish the infection, the heavy 

 cost in life at which nature is protecting the race 

 against that particular malady may be unnecessary. 

 The energy thus saved may more usefully be expended 

 otherwise in other selective processes, and our race 

 may advance in ability, strength or beauty, instead of 

 in immunity to tuberculosis or measles. Doubtless, 

 some suffer from those complaints as a sign of a 

 general unsoundness ; but many who succumb may 

 possess valuable properties in other directions pro- 

 perties which the world can ill afford to lose. As our 

 knowledge grows we may discover how to separate the 

 good qualities from the bad ones, to winnow the chaff 

 from the wheat without losing both. The believer in 

 selection may help forward efforts for the amelioration 

 of the lot of mankind with a clear conscience, provided 

 that it is fully realized that such efforts lessen the 

 pressure of natural selection, and make necessary an 

 artificial selection to take its place. We have been 

 given a growing knowledge of heredity at the same 

 time as an increased skill in improving the environment. 

 There is therefore no excuse for falling into the new 

 dangers blindfold ; and to act on one aspect of the 

 knowledge while ignoring the other is as culpable as it 

 is unwise. Any training for social service such as is 

 now becoming frequent is of little or no use unless 

 the principles of heredity are taught and taken into 

 account. 



