2/0 



Experimental Transformation of Species 



y\^ 



Xr / 



994 



1^ 



Fig. y^. Crossing-over of Linked Characters 



If a male having two recessive mutant characters, white eyes and yellow 

 wings, is mated with a wild female having red eyes and gray wings, the 

 offspring (left in F^ ) will all be of the wild type. If such a hybrid is 

 mated to another double recessive, four kinds of offspring will result (F^), 

 but instead of getting a typical Mendelian segregation, we find that 99% 

 are like the grandparents (dominant for both traits) and only 1% are 

 reversed. That is, there is linkage, but the linkage is not perfect. From 

 Morgan, The Theory of the Gene, published by Yale University Press. 



