INHERITANCE OF TRAITS ASSOCIATED WITH SKIN COLOR. 43 



not always fail to dominate, but, on the contrary, the simplex curl- 

 determiner may yield a curly condition of the hair. Theoretically, an 

 equality of straight and curved is to be expected, instead of which 25:38 

 is found. This is in part due to a failure to report the hair in describing 

 a child where it is straight (there are apparently several omissions of 

 this sort) and partly to classifying as straight-haired some persons 

 whose hair is really wavy or curly at the ends but is cropped short in 

 order to conceal the fact — ^for the near-white hides the curve in his 

 hair if he can. 



(C) The mating straight X curly yields only straight, wavy, and 

 curly (in all degrees). In a few cases (J. 4, J. 38), including all where the 

 hair of the one parent is "very curly," the progeny have all curly hair. 

 Otherwise the hair of the progeny is straight, wavy, or curly. Assuming 

 that there would be straight-haired offspring in cases only where the 

 curly parent carries straightness, we expect 50 per cent of the offspring 

 to have straight hair. Counting only fraternities that include both 

 straight- and curved-haired offspring, we find 35 straight to 50 curved 

 of all grades. Here, again, the deficiency of "straight" offspring is 

 probably due to a failure to report a few straight-haired children. The 

 result is of the order of expectation. 



(D) The mating straight X kinky gives rise, prevailingly, to curly- 

 haired offspring. However, there is one case of a pure-bred, kinky- 

 haired negro who had a 3 -months-old child whose hair is straight (but 

 such children usually develop curly hair subsequently). In all the other 

 cases where there are "straight" children the kinky-haired parent has 

 about three-fourths negro blood. The case of J. 51 is remarkable. In 

 general, kinky does not carry straightness, but apparently may do so 

 (J. 51). The heterozygous condition is evidently wavy or curly. 



(E) The mating straight X woolly occurred once and there was 

 only one child, and it had kinky hair. 



(F) The product of two wavy-haired parents is straight, wavy, and 

 curly-haired offspring in roughly 1:2:1 proportions — again evidence 

 of the heterozygous nature of waviness. 



(G) Wavy X curly gives mostly wavy and curly offspring, again 

 the product of c+C and C+C determiners respectively. But there 

 are some straights, indicating that some curly-haired parents have 

 "straight" germ-cells, as we saw under (C). 



(H) Wavy X kinky crosses yield a very few straights and 2 woolly; 

 but most of the children have wavy or curly (heterozygous forms of 

 kinky). 



(I) Curly X curly yields mostly curly; yet some curly parents 

 apparently carry "straight" as a recessive character, so that 14 per 

 cent of all offspring belong to that category. 



(K) Curly X kinky. — In this, our extreme union of curly types, 

 only curly and kinky occur in the children (i fraternity). 



