278 HEREDITY AND ENVIRONMENT 



father and normal mother will appear normal 

 although carrying one determiner for color 

 blindness, while all the sons will be normal be- 

 cause they carry no determiner for color blind- 

 ness. But these daughters transmit to one-half 

 of their children the single determiner for color 

 blindness and if any of those receiving this de- 

 terminer are males they will be color blind. 

 Consequently we have the curious phenome- 

 non of simplex color blindness appearing only 

 in males and being transmitted to them only 

 through apparently normal females. 



On the other hand if a female is color blind 

 she has inherited it from both father and 

 mother, i.e. the character in her is duplex, and 

 in all of her children by a normal male the 

 character will be simplex; accordingly all of 

 her sons will be color blind and all of her 

 daughters will be normal, though carrying the 

 simplex determiner for color blindness. 



In all cases dominance means merely the 

 development in offspring of certain characters 

 of one parent, while contrasting characters of 



