32 THE RELATIVE STRENGTH OF 



influencing man's welfare, gives us reason to pause 

 when we consider the methods of modern social 

 reform. 



The question of the respective influences of 

 heredity and environment is becoming one of vital 

 importance. It seems only too true at the present 

 time that the physically and mentally weaker stocks 

 are reproducing themselves at a greater rate than 

 those of sounder physique and intelligence. 



This, unchanged, must mean that the average 

 physique and ability of our nation as a whole will 

 decline and must decline unless we can prove that by 

 a better environment we can raise the level of the 

 community. So far as our investigations have gone 

 at present they show clearly the small influence of 

 environment ; work of the mother, an unhealthy 

 trade of the father and the drinking of the parents 

 seem to have very litde influence on the physique of 

 the children. Overcrowding, bad economic con- 

 ditions, bad physical and moral conditions of the 

 parents have practically no effect on the intelligence, 

 eyesight, glands and hearing of the children. It is 

 possible that better measurements of environmental 

 characters than we yet possess may show more cor- 

 relation, and it is also possible that other characters 

 may prove more influential. But so far as our 

 researches reach I think we have shown that it is 

 quite easy to demonstrate a large hereditary factor, 

 and it is not at all an easy thing to show that any of 

 the environmental factors we have measured up to 

 the present time have any important effect on the 

 children. Not only are the correlations low but we 



