424 HEREDITY AND ENVIRONMENT 



There are millions of men in civilized 

 countries whose mental equipment places them 

 on a plane with barbarians or savages, and 

 they have on the average more offspring than 

 their civilized contemporaries. There are mil- 

 lions of others who are so seriously defective 

 in body or mind, owing to hereditary causes, 

 that they can never take care of themselves and 

 must always be a charge upon the state, and 

 yet in many civilized countries they are per- 

 mitted to perpetuate their kind and produce 

 an ever-increasing supply of mental and 

 moral defectives, whose maintainance must 

 seriously interfere with the proper education 

 and development of the normal population 

 and whose unrestrained existence constantly 

 threatens to pollute purer streams of heredity. 

 The practice of society regarding marriage 

 and reproduction up to the present has been 

 to allow all sorts, good, bad and indifferent, to 

 propagate with the belief that good environ- 

 ment and training may make up for deficien- 

 cies of birth. But very recently the conviction 

 has been growing that good environment is far 

 less important than good heredity and that in 



