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THE AMERICAN NATURALIST [Vol. XLV 



Family 42 is apparently duplex or honiozygote with a 

 gametic composition of ccXcc, but there is nothing to 

 indicate whether the curly hair is dominant or recessive. 

 The wavy haired families behave as if simplex or hetero- 

 zygote, producing both straight and curly-haired children. 

 If wavy hair is produced by a combination of straight 

 and curly it should behave as it does, representing the 

 heterozygote of the F 1 generation, and in the next genera- 

 tion (F 2 ) there is a return of the two original forms of 

 hair, curly and straight, and a continuance of the wavy. 



In some straight X curly families, curly hair seems to 

 be dominant, as in 14, 16, 29, 33 and 39. Whereas in 

 others straight hair seems to be dominant, as in 7, 18, 26, 

 27, 28, 30 and 45. It will be noted that whatever the 

 character of the father's hair, that character is dominant 

 except in family 39. It is also to be noted that straight 

 hair is dominant when three of the grandparents have 



two of the grandparents have curved hair. If the hair 

 form of the dominant parent is duplex no recessives are 

 to be expected, but if the dominant parent is simplex half 



