Inheritance of Physical and Mental Traits 



275 



of a prevailing brown head of hair. This spotted condition 

 is due to a positive factor, just like spottedness in mice. 

 From a spotted parent at least half the offspring are spotted; 



FIG. 82. Pedigree of a family with tyloses (T). Note that 11 affected per- 

 sons have at least one parent affected. UNNA. 



r 



OrB BrO rD B,O BiO * 6rD 



I I 3N I r i 



FIG. 83. Pedigree of faulty enamel of teeth. This peculiarity appears only 

 in the offspring of an affected parent, consequently it is a positive trait. TURNER. 



but a person with uniform coat belonging to the spotted 

 strain will have no children with the white patch. 



Probably the same law is followed in the case of families 

 without teeth and also in families with faulty enamel of the 

 teeth (Fig. 83). Apparently there is a determiner that 



