PHENOMENA OF INHERITANCE 283 



to produce a color blind male, just as is true 

 of sex. The accompanying diagrams (Figs. 

 61, 62) illustrate the method of inheritance of 

 color blindness. As in the previous diagrams 

 X represents the sex-determiner, © its absence, 

 and X the sex-determiner which carries the 

 factor for color blindness. 



It will be seen that a color blind father and a 

 normal mother have only normal children, 

 but the father transmits to his daughters 



Chromosomes 



XX Parents 



x © en 



I X I _ Gametes 



X x ?J 



IXI Gametes 



X^@ <$j 



<©> «> <S <S> M XX m X9 f» 



? ?d , c? 9 ? cT d^ 



Fig. 62. Diagram of inheritance of color blindness through 

 the female. A color blind female transmits her defect to all 

 her sons, to half of her granddaughters and to half of her 

 grandsons. Corresponding distribution of sex chromosomes on 

 right. (After Morgan.) 



