738 



77/ 7-: . I MEB1CAN NATURALIST [Vol. XLVII 



Summary. — The foregoing pages are given to a study 

 of left-handedness among 610 parents and 1,130 children, 

 the data being collected from students at the University 

 of Colorado. It is concluded that left-handedness is a 

 Mendelian recessive. The condition probably exists in 

 about one sixth of the population. A suggestion is made 

 that the three Mendelian types of individuals may exist 

 in some such proportion as 9 homozygous right-handed: 

 12 heterozygous right-handed -A left-handed. 



P.. JlnjI,! lunnhd Parent Probably 



Right-handed 





■*«- 





Na Rep o f rtin r g 01 ' ''niiw'Jeii ^ 





Ba 



1 











Pi 3 



Bl 



Du 



Spr \ 2 



Mi 



27 





1U • 



is Mendelian expectation requires that all the children of these families be 

 naturally right-handed and that the left-handedness was only acquired. If 

 ance of the right-handed child. 



