10 HEREDITY AND SOCIAL FITNESS 



they belong for the most part to our great middle class. Still, their 

 history shows the establishment of lines which vary greatly from the 

 standpoint of social efficiency. The history of each line has been 

 traced as it rnoves up or do^^^l through matings made under the eugenic 

 conceptions of the time. Moreover, since these families trace back to 

 immigrants of more than a century ago, they furnish concrete cases 

 bearing on the contentions of our immigration problems. 



The study began with four young people, patients at the Institution 

 for Feeble-Minded at Polk, Pennsylvania. It had not proceeded far 

 before the wide variability of the material became apparent, especially 

 with reference to sense of number and proportion, general mental 

 ability, and such traits as aggressiveness and perseverance. The 

 investigation was then carried back to the founders of the families and 

 extended to include all individuals of their normal lines so far as they 

 could be determined. The whole has been viewed as a complex experi- 

 ment in marriage selection, whereby strongly contrasting lines have 

 arisen. Their evolution, it is felt, suggests an answer to our question 

 as to the means by which original defects, on the one hand, persist in 

 a family, or, on the other hand, are made good by traits which insure 

 increased social efficiency. 



No one can feel more keenly than the author how far she has fallen 

 short of her ideal in this work. It is offered simply as an imperfect 

 attempt along relatively new lines, and in the hope that it may serve 

 as stimulus to more exhaustive and critical studies in the same field. 



Grateful acknow^ledgment is made to Dr. J. Moorhead Murdoch, 

 Superintendent of the Institution for the Care of the Feeble-Minded of 

 Western Pennsylvania, Polk, Pennsylvania, for according the author 

 exceptional facilities for this extensive research as well as genetous 

 interest in each step of its advance, and to the staff of officers and 

 teachers for cordial cooperation at all times. She also washes to express 

 her continued indebtedness to Dr. Charles B. Davenport, Director of the 

 Eugenics Record Office, who has given new direction to an earlier interest 

 in the study of heredity and who has followed the course of these in- 

 quiries with encouraging suggestion and helpful criticism. 



