66 MENDELISM CHAP. 



producing equal numbers of " black " and " white 

 splashed " gametes. The view was tested by breed- 

 ing 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 selec- 

 tion 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 deter- 

 mining 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 

 inhibiting factor which prevents the manifestation 

 of the black. Either interpretation fits the facts 

 equally well, and until further experiments have 

 been devised and carried out it is not possible to 

 decide which is the correct view. 



Besides these comparatively rare cases where the 

 heterozygote cannot be said to bear a closer re- 

 semblance to one parent more than to the other, 

 there are cases in which it is often possible to draw 



