THE ORIGIN OF FLOWERS 205 



Plateau in Ghent was the first to collect /acfe which appeared to 

 • contradict the Darwinian theory of flowers ; he observed that insects 

 avoided artificial flowers, even when they were indistinguishable in 

 colour from natural ones as far as our eyes could perceive, and he 

 concluded from this that it is not the colour which guides the insects 

 to the flowers, that they find the blossoms less by their sense of 

 sight than by their sense of smell. But great caution is required in 

 drawing conclusions from experiments of this kind. I once placed 

 ■ artificial marguerites {Chrysanthemum leucanthemum) among natural 

 ones in a roomy frame in the open air, and for a considerable time 

 I was unable to see any of the numerous butterflies (Vanessa urticoi), 

 which were flying about the real chrysa.nthemums, settle on one of 

 the artificial flowers. The insects often flew quite close to them without 

 paying them the least attention, and I was inclined to conclude that 

 they either perceived the diflference at sight, or that they missed the 

 odour of the natural flowers in the artificial ones. But in the course 

 of a few days it happened twice in my presence that a butterfly 

 settled on one of the artificial blooms and persistently groped about 

 with fully outstretched tube to find the entrance to the honey. It was 

 only after prolonged futile attempts that it desisted and flew away. 

 That bees are guided by the eye in their visits to flowers has been 

 shown by A. Forel, who cut off the whole proboscis, together with the 

 antennae, from humble-bees which were swarming eagerly about the 

 flowers. He thus robbed them of the whole apparatus of smell, and 

 nevertheless they flew down from a considerable height direct to the 

 same flowers. An English observer, Mr. G. N. Bulman, has been led 

 to believe, with Plateau, that it is a matter of entire indifierence to 

 the bees whether the flowers are blue, or red, or simply green in 

 colour, if only they contain honey, and that therefore the bees could 

 have played no part in the development of blue flowers, as Hermann 

 Miiller assumed they had, and that they could have no preference for 

 blue or any other colour, as Sir John Lubbock and others had con- 

 cluded from their experiments. This is correct in so far that bees 

 feed as eagerly on the greenish blossoms of the lime-tree as they do 

 on the deep-blue gentian of the Alpine meadows or the red blossoms 

 of the Weigelia, the dog-roses of our gardens or the yellow butter- 

 cups (Ranunculus) of our meadows; they despise nothing that 

 yields them honey. But it certainly does not follow from this 

 that the bees may not, under certain circumstances, hav0 exer- 

 cised a selecting influence upon the fixation and intensification 

 of a new colour-variety of a flower. This is less a question of 

 a colour-preference, in the human sense, on the part of the 



