ON THE WATSONIA 



either retained the ancestral color unmodified 

 because it served them well in adaptation to their 

 environment; or they are plants in which the re- 

 cessive blue, which must occasionally appear in 

 the course of hybridizations, was preserved and 

 restored to prominence because it served its 

 purpose better than the other colors, whatever 

 they might be, that had supplanted it. As might 

 be expected, deep or indigo blue flowers are more 

 abundant than light or pure blue ones. 



It is perhaps not without significance that blue 

 flowers have usually a white counterpart — the 

 bluebell furnishes a familiar example. Blue and 

 white, according to the theory just presented, lie 

 close together in the evolutionary scale. Either 

 will be recessive to red or orange or violet; and 

 it is only flowers from the germ plasm of which 

 these dominant colors have been largely removed 

 that are likely to develop blue or white races. 



Yet the fact that the white flower carries a 

 strain of yellow is an ever present menace to its 

 whiteness, as it may furnish the basis at any time 

 for variation that will introduce yellow strains 

 which stand a good chance of supplanting the blue 

 and white ones. 



Some further illustrations of the application of 

 this theory of the evolution of color in flowers will 

 appear in our subsequent studies. For the rest, 



[303] 



