284 Retrograde Varieties 



brid with the purple veins and center in the 

 corolla of the former, the white and blue thorn- 

 apple produce a blue hybrid, and so on. In- 

 stances of this sort are common in cultivated 

 plants. 



Having given this long list of examples of the 

 rule of the dominancy of the active character 

 over the opposite dormant unit, the question 

 naturally arises as to how the antagonistic 

 units are combined in the hybrid. This ques- 

 tion is of paramount importance in the consid- 

 eration of the offspring of the hybrids. But 

 before taking it up it is as well to learn the real 

 signification of recessiveness in the hybrids 

 themselves. 



Eecessive characters are shown by those rare 

 cases, in which hybrids revert to the varietal 

 parent in the vegetative way. In other words 

 by bud-variations or sports, analogous to the 

 splitting of Adam's laburnum into its parents, 

 by means of bud-variation already described. 

 But here the wide range of differentiating char- 

 acters of the parents of this most curious hybrid 

 fail. The illustrative examples are extremely 

 simple, and are limited to the active and inactive 

 condition of only one quality. 



An instance is given by the long-leaved vero- 

 nica {Veronica longi folia), which has bluish 

 flowers in long spikes. The hybrid between 



