30 



GENETICS 



of chromosomes, with a normal red-eyed male, having a 

 normal (black) X (sec figure 12). Now half of the off- 



Mother 



XC 



Father 



Baughterd 



Sons 



"D X 



XC 

 X 



Figure ii. Inheritance of a recessive characteristic that depends on 

 a particular type of X-chromosome: white eyes. The mother has 

 white eyes, the father red eyes (represented in black). The X-chromo- 

 somes of each individual are represented below the figure of the head, 

 the mother's chromosomes in outline, the father's in black. The 

 daughters, receiving one X-chromosome from each parent, have red 

 eyes, like the father. The sons, receiving an X-chromosome from the 

 mother only, have white eyes, like the mother. The white eyes appear 

 wherever the maternal type of X (outline) is the only type of X 

 that is present. 



