44 HEREDITY OF SKIN COLOR IN NEGRO-WHITE CROSSES. 



G. CORRELATION OF CHARACTERISTICS IN HYBRIDS. 



We have seen that from two mulatto parents there may arise a 

 child with a white skin or a child with a full black skin, as well as chil- 

 dren with an intermediate skin color. We have now to consider the 

 question : In how far is the absence or presence of negro skin pigment 

 associated with the absence or presence of other negro characteristics? 

 Unfortunately, we have not data for answering this question fully. 

 But there are two traits that are associated with dark pigmentation 

 of the skin in the negro of which we can trace the association in the 

 offspring of hybrids, namely, color of the hair and form of the hair 

 (degree of curving). 



For this study the fraternities listed in table 19 only were used. 

 This table gives the fraternities derived from two FI mulattoes (or else 

 two medium-colored persons who probably transmit as FI mulattoes 

 do). The reason for selecting the fraternities listed in this table is to 

 insure that both parents are truly of hybrid origin, and, consequently, 

 form germ-cells with determiners for both Caucasian and negro charac- 

 teristics, and hence may have children with any desired combination of 

 these characters, in so far as the characters are dissociable. 



I. CORRELATION BETWEEN THE COLOR OF THE SKIN AND OF THE HAIR IN 



THE F 2 GENERATION. 



Correlation can be quantitatively expressed when both characters 

 considered have been measured. Skin color has been measured in our 

 study, but hair color has not been. However, we may get closely to 

 the desired result by forming the series : flaxen, light brown, medium 

 brown, dark brown, and black, and assigning to these the values 1,2, 

 3, 4, 5, respectively. Then our correlation surface is formed as in 

 table 33. 



TABLE 33. Correlation between color of the skin and of the hair. 



N. B. The tabular entries indicate the frequency with which the given correlation occurs. 



The correlation calculated from this table is + 0.44 0.07. This 

 indicates that, as the skin color of the children is light or dark, the 

 hair color is light or dark respectively, with a degree of correlation 



