SEX LINKAGE 



375 



diagram, for the farther apart the genes are the more 

 chances there are that a break will occur between them. 



Sex Linkage. Since the sex of an individual in many- 

 animal species is determined by its chromosomes it would 

 naturally be expected that some characters would be 



Fig. 109. — Crossing-Over in Cross Between Gray Vestigial and 

 Black Long. The symbols and results are the same as in the last 

 diagram except that the genes are linked differently. The second 

 hybrid generation shows again about 5 times as many grandparental 

 types (i.e. this time gray vestigial and black long) as recombina- 

 tion types. 



Morgan, Phys. Basis. 



