76 



CELL HEREDITY 



mt 



alb 



11 I 



+ -■ 



? 



_ 1- 

 I 



? 



T- + + 

 Single Crossing Over 



1^< 



+ + + + -TT- +t +t 



Two-Strand Double Crossing Over 



■}•} 



•t 1 



_ 1_ 



t- +t +t 

 Three-Strand Double Crossing Over 



No new combinations 

 and first-division 

 segregation of color 



50 Per cent new 

 combinations and 

 second-division 

 segregation of color 



4+ -li. 

 ' I 



> 



.-:>. 



1^ 



1 - i. 

 9 ? 



- 1-4 4 



Four-Strand Double Crossing Over 



100 Per cent new 

 combinations and 

 first-division 

 segregation of color 



FIGURE 3.6. The consequences of single and various kinds of double crossing over. 



