XII THE CHROMOSOME THEORY 143 



went to form the F^ female. Further, if we suppose 

 that the point of junction may occur with equal 



N 



^1 

 i 



B 

 V 



C 



CI 



Fig. 42. 



Diagram illustrating the process of " crossing-over " between paired chromosomes. 

 When the point of junction is situated as in A or B, the gametes formed are 

 " non-crossover " gametes in respect of the factors G and A'. When the point of 

 junction is situated as in C, the gametes formed are "crossover" gametes in 

 respect of G and N. 



likelihood at any point along the chromosomes it 

 is clear that the chance of two factors becoming 



