Case III. Color-blind male X carrier female. 



CX 



Y 



male gametes 



Female 

 Gametes 



CX 



cX 



i.e. Half the males are color-blind and half normal. Half 

 the females are color-blind and half carriers. 



Case IV. 



Normal males and color-blind females. 

 cX Y = male gametes 



Female 

 Gametes 



CX 



CX 



CXcX I CXY 

 carrier 1 col. -bl'd 

 female male 



CXcX CXY 



Carrier icol.-bl'd 

 female I male 



i.e. The females are carriers and the males color-blind. 

 Case V. Color-blind male and color-blind female. 



CX Y = male gametes 



CXCX CXY 

 CX 



Female 

 Gametes 



CXCX 



col.-bl'd 

 female 



CX 



CXCX 



col.-bl'd 

 female 



CXY 



col.-bl'd 

 male 



CXY 



col.-bl'd 

 male 



i.e. All are color-blind. 



Drosophila Hybrids (See also page 120) 



Morgan's investigations on the inheritance of characters 

 in Drosophila ampelophila, the Pomace Fly, furnish very 

 complete records of sex-limited inheritance. This fly has 

 red eyes normally but a few white-eyed forms were observed 

 and used in crossing experiments. The following examples 

 illustrate some of the simpler cases of inheritance. The re- 

 sults are explained on the assumption of the presence of the 

 factor for Red-eye (R). the absence of this factor (r), and 

 the sex factors as in the case of color-blindness in man. The 

 X chromosome carries the factor for color. 



112 



