240 



GENETICS 



Parents 



Gametes 



Gametes 



Expectation ] 

 tnMendelian } 

 Assortment J 



.Artwtl Results- 41. 5 # 



Linkage 



Cross-overs 



FIG. 71. Typical cross-over in Drosophila. Symbols as in Fig. 68. 

 Data from Morgan. 



is quite a different thing since Mendelian segregation 

 involves whole chromosomes while cross-overs involve 

 only parts of chromosomes. The percentage too of the 



