510 



HUMAN INHERITANCE 



one which is not yet certainly or fully understood. The 

 fact appears to be that a hybrid between a light skinned 

 Caucasian and a dark skinned Negro is usually about 

 midway between the parents in color (Fig. 147). Dark 

 skin appears thus to be, like the red color in the four 

 o'clock described in Chapter XXVIII, only partially 

 dominant over light. However, when the pink four 

 o'clocks are selfed or inbred the Fj consists of 1 red: 

 2 pink: 1 white, while the medium colored mulat- 

 toes when inbred do not segregate cleanly into 



Fio. 147. — Inhpritnnce of Skin Color and Hair Form. The family 

 of a kinky-haired African Negro and a straight-haired English- 

 woman. Note the dominance of the kinky over straight hair and 

 the varying color of the children due to the fact that the dark parent 

 was not pure for all the color genes. 



Plate, Vcrerhnngfdehre. Englemann. 



3 classes in the 1:2:1 ratio. In fact, they produce 

 several shades of color of which it rarely happens 

 that any are either as light or as dark as the grandparents. 

 This result strongly resembles that obtained in the cross 

 of the red-grained wheat by the white-grained one 

 described in Chapter XXXI. The current explanation 

 assumes that the Negro and the Caucasian races differ 



