246 PRINCIPLES AND CONCLUSIONS. 



disks. He also declared that his experiments with artefacts demonstrated 

 that honey-bees possess the perception of space, form, and color. Practi- 

 cally all other students of experimental pollination have agreed that insects 

 are guided in some degree by form, though Giltay thought that visits to 

 a single petal indicated that form could not be concerned. This does not 

 follow, however, since it is evident that color is often more potent than 

 form. Detto was also doubtful of the ability of bees to see forms, but he 

 explains certain of his results on the assumption that the bees were able to 

 recognize the stamens and pistil of a flower. The Peckhams, Dahl, Andreae, 

 Wery, Frisch, and Turner have shown that insects distinguish forms or 

 patterns, and some of Lovell and Allard's results permit no other conclusion. 

 Additional proof is furnished by the readiness with which they go from one 

 color to another of flowers of the same species or variety, whether fragrant 

 or not, and especially by their response to painted flowers. The minuteness 

 with which they can distinguish forms and structures is proved by the ease 

 with which they solve the problems presented by inverted and mutilated 

 flowers, as well as by the ingenious experiments of Detto on the relative 

 importance of vision and smell in enabling insects to locate the nectary open- 

 ings. Finally, it appears that insects can distinguish differences in surface 

 and texture sufficiently small to escape man. This conclusion seems un- 

 avoidable, when one recalls the readiness with which bees often distinguish 

 between the best of artificial or painted flowers and normal ones. In fact, 

 it is a curious paradox that Plateau, who thought insects distinguish neither 

 form nor color, and that Forel, who thought they had but a vague vision 

 of form, should have believed that they were able to discriminate between 

 artificial and natural flowers by means of other differences not visible to 

 the eyes of man. 



ATTRACTION AT A DISTANCE AND NEAR AT HAND. 



It is unfortunate that no definite experiments have been made as to the 

 distance at which various colors and odors as represented in flowers exert 

 attraction, but it is hoped that the experiments now contemplated will 

 yield accurate quantitative results. The general opinion has been that 

 odor attracts from a distance and color near at hand, and Plateau has defi- 

 nitely stated that insects do not perceive objects at a greater distance than 

 2 meters and many of them only when much nearer. On the other hand, 

 Wery believed that color could attract for a distance of 6 meters, since 

 insects were able to recognize artificial blossoms placed this far from natural 

 ones, and Andreae stated that honey-bees could see 8 to 10 meters at least, 

 basing this upon similar grounds. 



The careful consideration of previous experiments confirms the evidence 

 derived from the present investigation. This indicates as the best working 

 hypothesis for further studies the conclusion that odor attracts for distances 

 beyond 10 meters, color in mass for the intermediate ones, and color and 

 form in detail within a meter or so, depending greatly upon the size and 

 color of the flower or cluster. For the majority of flowers without a marked 

 fragrance, odor can be effective only when near at hand and the effect is 

 probably small even then. It is hardly necessary to point out that this 

 must be true of color also in the case of green or dull flowers and especially 



