iv INTRODUCTION 



demonstration of ''hereditary criminality," "hereditary 

 pauperism," ''hereditary degeneracy," and so on. It is 

 nothing of the kind, and its author never made such claim 

 for it. He undoubtedly believed in the hereditary trans- 

 mission of character tendencies, as of physical traits, and 

 here and there he points out what seem to him to be 

 evidences of ''heredity," in this sense, in the "Jukes" 

 blood. But he is ever careful to say "seemingly," or 

 "apparently," or otherwise to warn the reader that the 

 conclusion is tentative. Far from believing that heredity 

 is fatal, Mr. Dugdale was profoundly convinced that 

 "environment" can be relied on to modify, and ulti- 

 mately to eradicate even such deep-rooted and wide- 

 spreading growths of vice and crime as the "Jukes" 

 group exemplified. 



Since Mr. Dugdale 's studies came to a too early end the 

 whole subject of heredity has undergone re-examination 

 at the hands of biologists. Notions that satisfied Mr. 

 Darwin have profoundly been modified by Weismann*s 

 contention that acquired characteristics are not trans- 

 missible, and by the discovery of the MendeHan law. 

 No scientific man of good standing would now venture 

 to affirm that we know enough about human heredity 

 to justify the social reformer in basing any very radical 

 practical program of social reform upon biological con- 

 clusions. We can only say that probably heredity is a 

 fateful factor in the moral, and therefore in the social, 

 realm, but that we need an immense amount of patient 

 research to determine exactly what it is, and what it does. 



The incontrovertible conclusion that Mr. Dugdale 's 

 investigations establish, then, is this: The factor of 

 "heredity," whatever it may be, and whether great or 



