OF A CERTAIN PENNSYLVANIA FAMILY. 



83 



where it is possible to determine with fair accuracy the training received 

 and where it is well known that the individual will stop short at 

 definite stages of achievement, no matter what are his advantages in 

 the matter of formal instruction. 



While it is possible by studying the individual from many sides to 

 form a judgment as to his rating with reference to this trait, the diffi- 

 culty is greatly enhanced when he belongs to a generation that is past. 

 It should be remembered that the environment for most of the persons 

 concerned has remained comparatively simple and uniform. Further- 

 more, the trait has been evaluated in relation to other elements of his 

 makeup, as well as the chief influences in his surroundings. 



While, therefore, the classes could not be made with the same degree 

 of definiteness as for calculating abiUty, still it is beUeved that the 

 familiarity with the material was sufficient for classification into three 

 grades — a low, a medium, and a high degree of aggressiveness. If we 

 conceive the different degrees of this trait to be due to comparative 

 presence (A) or absence (a) of determiners from the germ-plasm, we 

 may contrive a distribution of grades of the trait for the offspring 

 according to Mendel's law. This distribution would be the same as that 

 already given for calculating ability in the preceding section. The 

 produce of 80 matings, numbering 282 individuals, was classified and 

 compared with the theoretical expectations. The results are given in 

 table 3. 



Table 3. — Aggressiveness. 80 matings, 282 individuals. 



Here, again, the realized percentages would indicate a segregation 

 of the elements of the trait. The considerable discrepancy between 

 the expected and the realized results in matings (3) and (4) is no doubt 

 due to varying environmental influences and the difficulty of evaluat- 

 ing the various grades of the trait. It will be observed that this dis- 

 crepancy is considerable only where both parents are moderately 

 aggressive, or where one has a very low grade while the other has a 

 very high grade of the trait. In both of these cases the offspring show 

 greater resemblance to the parents than would be expected from the 

 formula. This is probably to be explained by the effect of parental 

 example. 



