OF A CERTAIN PENNSYLVANIA FAMILY. 85 



where aggressiveness, perseverance, calculating ability, and, finally, 

 unusual mechanical ability all converge toward their presence in VI-20. 

 Another significant series of combinations occurs in Line C, whereby 

 defects concentrate in a single member in the third and fourth genera- 

 tions, the latter (IV-81) dying without issue, while the combination 

 of medium or high aggressiveness and perseverance with calculating and 

 other mental abilities produces good average efficiency of various 

 types in the representatives of later generations. 



Should this principle of segregation prove capable of further exten- 

 sion in the domain of mental and temperamental traits, it will provide 

 a means of more accurate prediction as to the outcome of given matings 

 and the trend of development in particular strains. Such extension 

 should prove highly valuable for the evolution of a constructive 

 eugenics. 



The theoretical bearings of these results are more far-reaching than 

 would at first appear. From this study and others the writer is con- 

 vinced that it is by such quantitative ratings of inherent traits that 

 we shall be able to make a more minute analysis of the personality 

 than has hitherto been attempted. With such quantitative ratings 

 and the principle of segregation as illustrated in this network, we 

 ought to be able to trace the factors contributory to many cases of 

 sporadic feeble-mindedness and the occurrence of unexpected immoral 

 and insane tendencies in persons springing from fair stock. In this 

 way much might be accomplished without the highly desirable objec- 

 tive tests that the modern applications of psychology are promising. 

 Indeed, there is no reason why this detailed analysis should not 

 accompany and in many cases point the way to essential refinements 

 of method now being attempted in the service of vocational guidance. 



