28 THE TREND OF THE RACE 



is often difJ6cult to estimate; but it requires no great discernment 

 to perceive that many rather confident expressions of opinion are 

 based on lack of familiarity with the principles of hereditary 

 transmission, or a very inadequate acquaintance with the investi- 

 gations that have been made in this field. 



The method of investigation employed by the Eugenics Record 

 Office at Cold Spring Harbor, Long Island, is one that is in some 

 respects considerably superior to those commonly followed. 

 Instead of collecting mass statistics a more intensive study is 

 made of special cases. For this purpose trained field workers are 

 employed who make the acquaintance of the relatives of the 

 patients investigated, get into friendly relations with them, and 

 through personal impressions and a knowledge of their history are 

 enabled to form a tolerably accurate judgment of their mental 

 status. The full and careful study of several pedigrees of mental 

 defectives promises to throw more light on the precise method in 

 which mental defects are inherited than any amount of unana- 

 lyzed data collected from the loose records of institutions. Field 

 workers need to be psychologists skilled in the methods of meas- 

 uring intelligence and of detecting mental aberrations, and en- 

 dowed with the attributes of tact, patience and an ingratiating 

 personality. Data secured by field workers have already been 

 proven of considerable value in throwing light on the probable 

 mode of transmission of mental defect, although there is room for 

 considerable refinement of method and thoroughness of enquiry 

 in much of the investigation which has thus far been carried on. 

 The intensive study of pedigrees has been the chief method of 

 those whose aim it has been to show that mental defect is trans- 

 mitted according to Mendel's law. Whatever may be the issue of 

 the controversy over whether or not mental defects behave as 

 mendelizing unit characters, insight into the question can only 

 come by the thorough, critical and unbiased study of particular 

 pedigrees. 



