50 HEREDITY [ch 



cally ; it shows how little room is left in the 

 development of the individual for the effects of 

 environment even on the intellect or mind in the 

 broadest sense of the word ; no doubt the direction 

 which intellectual development takes is to a con- 

 siderable extent determined by circumstances, but 

 the kind of mind is irrevocably decided before the 

 child is born. Still less is there room for the 

 inheritance of the mental acquirements made by the 

 individual during his life, and hence the hopes held 

 out of improving the race by education and by 

 special care of the dull or feeble-minded are illusory, 

 except in so far as they improve the tradition. Just 

 as the welfare of the race may be increased by an 

 invention which is handed on from generation to 

 generation, so the good effects of education or other 

 improved conditions may be handed on, but this is 

 not heredity. The father may educate his children 

 because he himself was educated, but the mental 

 powers of his children will be the same whether he 

 had a good education or none. And the effects of 

 special care given to the weakly or feeble-minded 

 may be absolutely harmful to the race, if the im- 

 provement so effected leads to more frequent 

 marriage among such unfortunates than would other- 

 wise be the case, for then an increased number of 

 defective children may be born, and the race-average 

 be lowered. Hence has arisen the study known as 



