16 



THE THEORY OF THE GENE 



They are the crossovers, and represent interchanges be- 

 tween the two linkage groups. 



A similar experiment can be made in which the same 

 characters as before are differently combined. If a male 

 Drosophila with yellow wings and red eyes is mated to a 



Pi 



Fig. 12. 



The inheritance of the same two sex-linked characters of Fig. 11, 

 but in reciprocal combinations, vis., red eyes and yellow wings, and 

 white eyes and gray wings. 



