PSYCHOLOGY OF MENTAL DEFICIENCY 



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Fig. 2. Heredity Chart. Devised by Dr. Goddard, of Vineland, recently adopted 

 by the American Association for Study of Feeble-minded and the American Institute 

 of Criminal Law and Criminology and also used by Dr. Wm. Healy in his work in 

 the Juvenile Psychopathic Institute of Chicago. This chart gives in graphic form the 

 hereditary status of some cases at Vineland, N. J. Square = males ; circle = females ; 

 clear square or circle means no data ; F , feeble-minded ; A, alcoholic ; T , tuberculosis ; 

 N, normal ; C, criminal ; Sx, grave sexual offender ; d.inf. means died in infancy ; 

 small black dot means miscarriage. Hand points to the child that is in the Vineland 

 institution. 



At the present writing three hundred and nineteen members of this family have 

 been traced, one hundred and nineteen are feeble-minded and only forty-two are 

 known to be normal. 



problem being pursued. Dr. C. B. Davenport, who is the best authority 

 in this country on eugenics, writes in a paper, soon to go to press, as 

 follows : 



Application of Mendel's Law to Human Heredity 



For our purpose Mendel 's law may be regarded as consisting of three prin- 

 ciples. First, the principle of the unit characters of inheritable unit, each of 

 which is, in accordance with the second principle, transmitted through the germ 

 by a representative called a determiner. The third principle is that when the 

 germ cells of both parents carry a determiner of a character the fertilized egg 

 and the embrvo derived from it have the determiner of the character double or 



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Fig. 3. These Charts illustrate one Tendency in the Three Cases just 

 cited, i. e., mentally defective parents are very prolific. A very careful study made 

 by Dr. Tredgold in England revealed the fact that sixteen mentally defective women 

 working as mill hands had given birth among them to one hundred and sixteen 

 children. 



