vii DOMINANCE 71 



proportions, viz., one black, two blues, one splashed 

 white. This at once suggests that the black and the 

 splashed white are the two homozygous forms, and that 

 the blues are heterozygous, i.e., producing equal numbers 

 of "black" and " white splashed" gametes. The view 

 was tested by breeding the " wasters" together — black 

 with black, and splashed white with splashed white — 

 and it was found that each bred true to its respective type. 

 But when the black and the splashed white were crossed 

 they gave, as was expected, nothing but blues. In other 

 words, we have the seeming paradox of the black and the 

 splashed white producing twice as many blues as do the 

 blues when bred together. The black and the splashed 

 white " wasters" are in reality the pure breeds, while the 

 "pure" Blue Andalusian is a mongrel which no amount 

 of selection will ever be able to fix. 



In such cases as this it is obvious that we cannot speak 

 of dominance. And with the disappearance of this 

 phenomenon we lose one criterion for determining which 

 of the two parent forms possesses the additional factor. 

 Are we, for example, to regard the black Andalusian as a 

 splashed white to which has been added a double dose of 

 a colour-intensifying factor, or are we to consider the 

 white splashed bird as a black which is unable to show its 

 true pigmentation owing to the possession of some in- 

 hibiting factor which prevents the manifestation of the 

 black. Either interpretation fits the facts equally well, 



