22 



MENDELIAN SEGREGATION 



Vestigial 



P. 



Long 



Ebony 



f; 



GaMETOGENESIS orFJ 



Fig. 11. — Vestigial gray by long ebony fly, to illustrate the inheritance 

 of two pairs of characters. The factor for vestigial is carried by the 

 second, the factor for ebony by the third chromosome pair. In the lower 

 part of the figure the two modes of separation, of the two pairs of chro- 

 mosomes involved here, are represented. Four kinds of gametes result. 

 These four kinds combine at random in fertilization, so that 16 classes 

 are produced in F2, as shown in the next figure. 



