DOMINANCE 



69 



and coloured birds in the expected ratio. There seems, 

 therefore, little reason to doubt that the dominant 

 white is a coloured bird in which the absence of 

 colour is due to the action of a colour-inhibiting 

 factor, though as to the nature of that factor we can 



Fig. 14. 



Ears of beardless and bearded wheat. The beardless condition is dominant 

 to the bearded. 



at present make no surmise. It is probable that 

 other facts, which at first sight do not appear to be 

 in agreement with the " Presence and Absence " 

 hypothesis, will eventually be brought into line 

 through the action of inhibitor factors. Such a 



