No. G31] COLOR CLASSES IX DOVES AND CANARIES 173 



Zygotes expected: (1) PpFFMM= cte 



(.-5) PpRFMU^Ilr 

 (4) pPFFMm = ds 



Here again dark-eyed females are 

 color class produced. 

 In the reciprocal cross we should 1 



As in doves the dark-eyed females of class (4 > would be ex- 

 pected when crossed witli ordinary white males, to produce dark- 

 eyed females, an unusual color class, as well as dark-eyed males, a 



It Will then be seen thai the hypothesis of factorial change ac- 

 counts for all the observed facts ami unlike the hypothesis of 

 partial sex-linkage or that of non-disjunction expects neither 

 exceptional phenotypically distinct color classes as yet not ob- 



obtain at rare intervals colored doves from white parents. None 

 of those who reported exceptional colored females have reported 

 this event. Nor have breeders of pink-eyed canaries recorded a 

 dark-eyed bird from a pink-eyed V pink-eyed mating. In neither 



