No. 564] INHERITANCE OF LEFT— HANDEDNESS 



737 



In the above ratios RR is pure right-handed, 7iV is 

 heterozygous right-handed and rr is left-handed. 1 have 

 taken these particular proportions because they are stable 

 and they approximate to a degree the actual condition in 

 the population studied. As is noted in the table, the num- 

 ber of left-handed persons is probably greater than the 

 reports indicate. Some families reported as having both 

 parents right-handed evidently belong with the group of 

 one left-handed and one right-handed. Some reported in 

 this latter group belong, no doubt, with those having 

 both parents left-handed. 



table v 



One Parent Right-handed, the Other Left-handed 

 A. Bight-handed Parent Evidently Heterozygous (Families 36, Eight-handed 

 Children 88, Left-handed Children 55). 



Fecundity of Left-handed Families.— It is well known 

 that in certain species of animals races showing partic- 

 ular recessive traits have less vitality and perhaps less 

 reproductive ability than the ordinary members of the 

 species. From the studies herein recorded, especially iu 

 Table II, it is seen that the left-handed families are quite 

 as fertile as the normal ones. 



