MAIN RESEARCHES OF PLATEAU. 



155 



species, which eliminates the effect of differences of form, perfume, and 

 the abundance and accessibility of nectar or pollen, it has been seen that 

 they show a complete indifference to color, when the relative number of the 

 flowers of each color available is taken into account. Finally, it was ad- 

 mitted that insects perceive flowers from a distance, either because they 

 see colors as we do or because they perceive a certain contrast between 

 the flowers and their surroundings, and that concurrently with the sense 

 of smell, although to a considerably smaller degree, this visual perception 

 can direct them toward the mass of flowers. Once arrived there, however, 

 if the flowers differ from each other in color alone, they are perfectly indif- 

 ferent whether the corollas are blue, red, yellow, white, or green. 



Table 90. — Color preferences. 



Errors made by Anthidium. — Plateau (1899 2 :452) concluded that 

 the female of Anthidium manicatum was directed to the flowers of Salvia 

 horminum by the odor, since these were much smaller and much less con- 

 spicuous than the group of terminal bracts. In following her behavior it 

 is seen that she makes many mistakes ; she often returns to a flower already 

 visited, goes to partly faded flowers with the upper lip brownish, and even 

 to completely faded ones which fall with her, and finally alights uselessly 

 upon the buds. The male is frequently unable to see the female when the 

 latter is immobile, but perceives her instantly when she flies. Moreover, 

 he is often unable to recognize the same individual again, sometimes return- 

 ing to her twice. So much does he depend upon movement that more than 

 once he was seen to fly to females of other genera even, such as Megachile, 

 Anthophora, Apis, and an ichneumon fly. However, he did not disturb 



