No. 542] COLOR SENSE OF THE HONEY-BEE 95 



was of little consequence, since the proof is ample that in 

 the case of the staminate plants of Rhus typhina, as in 

 Salix, the pollen is an important factor in attracting 

 visitors. 



It is commonly believed that insects are attracted first 

 to the staminate flowers of entomophilous d'wecious plants 

 by their greater conspicuousness, from which subse- 

 quently they carry pollen to the pistillate flowers. For in- 

 stance, Miiller says of the dioecious flowers of Asparagus 

 officinalis: "This instance confirms Sprengel's oft-re- 

 peated rule that the male flowers of diclinic plants are 

 more conspicuous than the female, whence insects are 

 likely to visit the two kinds of flowers in their proper 

 sequence." 20 But it is clear that many insects never fly 

 to the pistillate flowers, since if they did the number of 

 visitors to the two kinds of flowers would be equal. This 

 is especially true of female bees, which, having obtained 

 their load of pollen, often return directly to the hive or 

 nest. Of the four bees taken on the pistillate flowers of 

 Rhus typhina only two had pollen on the scopa of the 

 hind legs. After collecting the pollinators of this species 

 for several seasons I think it probable that some of the 

 species of bees taken on the staminate flowers are never, 

 or very rarely, found on the pistillate blossoms. 21 Spren- 

 gel's rule must, therefore, be accepted with considerable 

 reservation. 



The observations on dioecious flowers not proving well 

 adapted for the purpose intended, owing to the presence 

 of pollen as an attractive factor, the following experi- 

 ment was tried. The flowers of Gerardia purpurea have 

 a rose-colored, campanulate corolla and a short bell- 

 shaped calyx. The species is common in this locality and 

 is sparingly visited by bumblebees. When a large bou- 

 quet of the flowers was placed in front of a hive of black 

 bees, it received very little attention. Apparently they 

 contained no nectar. I now placed in the throat of a 



30 Miiller, H., "The Fertilization of Flowers," p. 549. 



-This is also true of dichogamous flowers. Kobertson, C, "Flowers 



