310 LATE ORIGIN OF BLUE FLOWERS 



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

 species have long tubular flowers, specially adapted to 

 bees and butterflies, the yellow Gentiana lutea has 

 a simple open flower with exposed honey. 



Miillerand 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 

 their original colour. Thus Aquilegia vulgaris, Ajuga 

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

 tensis, Myosotis alpestris, 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 

 true that there are comparatively few blue flowers, still, 

 if we consider only those in which the honey is con- 

 cealed, and which are, as we know, specially suited to 

 and frequented by bees and butterflies, we find a larger 

 proportion. Thus, of 150 flowers with concealed honey 

 observed by Miiller in the Swiss Alps,^ 68 were white 

 or yellow, 52 more or less red, and 30 blue or violet. 



However this may be, it seems to me that the 

 preceding experiments show conclusively that bees do 

 prefer one colour to another, and that blue is distinctly 

 Lheir favourite. 



' Die Farhcti der Bliithen, p. 26. 

 ' Alpenbhmten, p. 492. 



