STUDIES IN HUMAN HEREDITY 



295 



appears hereditary would seem to further indicate this. Proximately, 

 ambidexterity signifies cerebral and brachial functional symmetry, probably 

 the result of structural symmetry. The question of ambidexterity will 

 be discussed more fully below. 



The following pedigree charts represent the result of an effort to fur- 

 ther extend the work in the hope of disproving or more firmly establishing 

 earlier more or less tentative views. 



o- 



O 



-D 



o-r-m 



Fig. 1. 



Pedigree chart, figure 1,* shows an inveterately left-handed child of 

 five years with left-handedness in both family lines. 



•-r-n 



OHH 



[5^i5i*nHid6i 6 666666 



I 



•ko Ambidexterity. 



Chart, figure 2, in general is almost identical. In both instances the 

 last generation may probably be regarded as a pure recessive of a cross 

 between a homozygote recessive (RR) and a heterozygote dominant (DR) . 



* Explanation of symbols: open square, right-handed or normal male; open circle, 

 right-handed or normal female; solid square, left-handed or affected male; solid circle, 

 left-handed or affected female ; half solid character, ambidexterity ; character first used 

 in fig. 23, left-handed individual of unknown sex; line without attached character, 

 normal individual of unknown sex; solid small circle (fig. 38), tuberculous individual 

 of unknown sex; open small circle, normal individual of unknown sex. 



