Page:Popular Science Monthly Volume 79.djvu/89

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PSYCHOLOGY OF MENTAL DEFICIENCY
PSM V79 D089 Heredity chart of mental deficiency and criminality.png

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 principles. 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 embryo derived from it have the determiner of the character double or
PSM V79 D089 Chart of prolific tendency in the mentally defective.png
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.