182 



Scientific Proceedings (68). 



no (1042) 



Inheritance of temperament. 



By C. B. Davenport. 



[From the Department of Experimental Evolution, Station for Experi- 

 mental Evolution, Cold Spring Harbor, Long Island, N. Y.] 



Temperament, which determines mood, is generally recognized 

 as having an hereditary basis. It is obvious, however, that the 

 method of inheritance is not a simple one, but what factors are 

 involved have not hitherto been plain. An examination of 150 

 matings of two persons the mood of both of whom is known as 

 well as that of their children and that of the children's four grand- 

 parents has afforded the means to test various hypotheses of 

 which the following seems to satisfy the conditions very closely. 

 There are two hereditary factors involved in temperament, one 

 of which makes for excitation, the absence of this for self-control. 

 The other factor is one that makes for cheerfulness as opposed to 

 depression ; the depression being the more easily possible because 

 of the absence of this factor for cheerfulness or normality. The 

 exciting and the normalizing factors and their absence may be 

 combined in the matings in over 50 ways, but for a given mating 

 the disposition of the offspring follows a definite law and the dis- 

 positions occur in certain proportions in a fraternity of brothers 

 and sisters. Dominance in the simplex condition is frequently or 

 usually imperfect so that a clear difference between the dis- 

 position of children who receive two doses and only one dose of a 

 factor can be recognized. The exciting factor may occur in the 

 child simultaneously with the factor for normality, in which case 

 the person is constantly or periodically elated and when depressed 

 he is not depressed below the normal. The absence of normality, 

 or depression, may occur without elation, in which case the person 

 is constantly or periodically depressed and when not depressed 

 does not rise above the normal. In still other cases factors for 

 elation and depression may both occur in the individual in which 

 case he may show elation and depression either simultaneously or 

 in succession. The latter gives rise to persons of alternating 

 mood and, in extreme cases, to circular insanity. 



