LINKED CHARACTERS 



eration hybrids, these hybrids do not (as hybrids with 

 independent characters do) give the same phenotypes in 

 the second hybrid generation either when back-crossed or 

 when mated with one another, as is set forth in detail 

 in the next paragraph. 



Back-Crossing Linked Characters. — If the long- 



FiG. 106. — The Cross Between Vestigial Gray and Long Black. 

 The symbols used in this diagram are the same as those in the last 

 one. However it should be noted that in this cross each parent con- 

 tributes one dominant gene, whereas in the last, one parent con- 

 tributed both dominants. In this case the first hybrid generation will 

 show both dominants and so, therefore, resemble one parent in 

 respect to body color and the other in respect to wing length. As the 

 diagram shows this does not involve any disturbance of the linkage 

 since the grandparental combinations of genes and their correspond- 

 ing characters reappear again in the second hybrid generation. 



Morgan, Phys. Basis. 



