LINKAGE 



83 



spring are of two kinds only, namely, black long, and wild- 

 type color vestigial. The combinations that went into 

 the cross together have come out together. The diagram, 



Fig. 34. — Back-cross of Fi male (out of gray vestigial by black) to black vestigial. 



based on the chromosomes, shows that the genetic results, 

 as before, follow the chromosome behavior, provided there 

 has been no interchange of genes in the male. 



For the sake of simplicity only two linked factors were 



