MENDELIAN SEGREGATION 



19 



r^ 



\^ \-/ 



(ip\ o 



\-y' \-^ 



Fig. 10.— Wliite-eyod female by red-oyed male (D. melanngastcr). 

 The factors for these" eharaeters are carried by tlie X chroniosoiiu^s. In 

 this diagram red is indicated by the symbol W ;md white by the symbol \v. 

 The history of the chromosomes is shown in the middle of the diagram. 



