138 



GENETICS 



over straight, represented by crooked and straight 

 lines respectively in the diagram. In other words, 

 the presence of pigment is dominant over the ab- 

 sence of pigment, while the factor that causes curli- 

 ness is dominant over the absence of this factor, 

 with respect to human hair. 



KEY TO SYMBOLS 



= Dark 

 O = Light 



= Curl 4 



- = Straight 



FIG. 45. The heredity of human hair according to data by C. B. and 

 G. C. Davenport. The arcs represent the somatoplasms of four indi- 

 viduals. Within the arcs are the gametes formed by these individuals. 

 The dominant character is placed on the outside of the arc where it 

 will be visible. 



