152 CHARLES MIDLO AND HAROLD CUMMINS 



the hand of the great ape and the human foot, where the 

 functional agreement would be negligible. In further illustra- 

 tion it may be pointed out that the human palm resembles the 

 soles of Old World monkeys and gibbon in the general principle 

 of possessing a diagonal field of left ascendancy separating 

 two zones of right superiority, a principle which is at least 

 potentially present also in the hand of Old World monkeys. 

 The complexity of the developmental substrate which leads to 

 bilateral differences in pattern intensity may be best ap- 

 preciated by considering the status of bimanual differences 

 in man. It must be remembered that the distinctions of right 

 and left hands are expressed only in trends, and that many 

 individuals lack expressions of such trends. Studies of right- 

 and left-handed individuals indicate that the prospective func- 

 tional dominance of one or the other hand plays some part in 

 regulating the dermatoglyphic expression in the individual. 

 The occurrence of racial differences in bilateral asymmetry 

 (see suggestion above in connection with bipedal differences, 

 also Poll, '38, on an expression of asymmetry in finger-tip 

 patterns) renders the situation all the more complicated. In 

 the other primates, as well, there may exist phenomena of 

 similar complexity. It would be hazardous to place undue 

 emphasis on bimanual and bipedal regional differences in 

 view of the small numbers on which the statistics are based. 



Aggregate asymmetries. Having dealt with regional asym- 

 metries in pattern intensity, a consideration of asymmetries 

 in which the whole members are variously compared may next 

 be introduced. Several measures of bilateral asymmetry, 

 based upon data in tables 7 and 8, are supplied in table 9 

 and discussed below: index of asymmetry; membral asym- 

 metry; total asymmetry; relative asymmetry of the palm. It 

 will be evident that cancellation effects may be introduced 

 when regional asymmetries are pooled. 



For arriving at the index of asymmetry of a genus the total 

 intensities of right and left palms or soles are expressed in a 

 proportion between right and left sides: 100 X (the larger 

 of the two total intensities whether right or left, divided by 



