PHENOMENA OF INHERITANCE 



277 



Sex-Linked Inheritance 



In this connection we may consider another 

 class of characters, which are linked with sex 

 but are in no wise connected with sexual repro- 

 duction. Such characters are not necessarily 

 limited to one sex or the other, as are many 

 Flies Chromosomes 



XX Parents 



? 



I Xl [ Gametes 



X X ? 



2YQ: 2X1 



c? S 



Fi 



I x | [ Gametes 



XI? 



XX xx xc 



9 9 c? 



Fz 



6 



? ? c? 6 



Fig. 59. Sex-linked inheritance of white and red eyes in 

 Drosophila. Parents, white-eyed male and red-eyed female; 

 F l9 red-eyed males and females ; F,, red-eyed females and equal 

 numbers of red-eyed and white-eyed males. The distribution 

 of sex chromosomes is shown to right of flies; X carries the 

 factor for red eyes, the factor for white eyes, q stands for 

 absence of Xi or presence of Y chromosome which is found 

 only in males. (After Morgan.) 



