LATE ORIGIN OF BLUE FLOWERS. 309 



varieties are whitish-yellow; the larger and in 

 highly developed, blue. Myosotia versicolor we know 

 is first yellow and then blue ; and, according to Muller, 

 one variety of V. tricolor alpestria is yellow when it 

 first opens, and gradually becomes more and more blue. 

 In tliis case the individual flower repeats the phases 

 which in past times the ancestors have passed through. 



The flowers of one species of Lantuna last three 

 days, and, as Fritz Muller first pointed out, are on the 

 first day yellow, on the second day orange, and on the 

 third day purple. 



The only other family I will mention is that of the 

 Gentians. Here, also, while the well-known deep blur 

 species have long tubular flowers, specially adapted to 

 bees and butterflies, the yellow Gejitiana lutea has 

 a simple open flower with exposed honey. 



Muller and Hildebrand ' have also pointed out that the 

 blue flowers, which, according to this view, are descended 

 from white or yellow ancestors, passing in many cases 

 through a red stage, frequently vary, as if the colours had 

 not had time to fix themselves, and by atavism assume 

 t h i r original colour. Thus A quilegia vulgaris, Ajuga 

 Genevensis, Polygala vulgaris, P. comosa, Salvia pro.- 



vi, MyoBotis dLpestria, and many other blue flowers, 

 are often reddish or white ; Viola calcarata is normally 

 blue, but occasionally yellow. On the other hand, flowers 

 which are normally white or yellow, rarely, I might 

 almost say never, vary to blue. Moreover, though it is 



1 IHc Farben der liliitAeH. p. 26. 



