354 LIGHT AND THE BEHAVIOR OF ORGANISMS 



persons can also distinguish different colors if they differ 

 in brightness as did those in Lubbock's experiments. 

 It does, however, demonstrate that internal factors are of 

 primary importance in these reactions. The selection of 

 a given color now and a different one some other time, 

 flight into the pitch darkness of their home at one moment 

 and out into the brightest sunlight the next, is surely not 

 the result of orientation unequivocally controlled by the 

 immediate environment. These reactions can be explained 

 only upon the assumption that some internal condition 

 regulates the change in reaction. 



Concerning the second conclusion of Lubbock, that bees 

 " prefer blue," it must be said that if this is anthropo- 

 morphically interpreted there is no solid foundation for 

 the conclusion, but if it is merely intended to indicate that 

 shorter waves having a given amount of energy stimulate 

 bees more strongly than longer waves having the same 

 amount of energy, there can be no doubt as to its validity, 

 unless the bees used in the experiments of Lubbock and in 

 those of Graber had been accustomed to collect honey from 

 blue flowers before the tests were made. 



Aside from those already mentioned there are numerous 

 other references to the reactions to color in ants, bees 

 and other arthropods in the literature on these subjects. 

 Among these may be mentioned those of Minkiewicz (1907), 

 Keeble and Gamble (1900), and Bell (1906) on decapod 

 Crustacea, those of the Peckhams and McCook on spiders, 

 and those of Graber, Forel, Plateau, Buttel-Reepen, Bethe, 

 Bulman, Miss Fielde, Darwin, Muller and Bonnier on ants, 

 bees, wasps and other insects. Much of the work of the in- 

 vestigators in the last group was directed toward the ques- 

 tion as to the influence of the color of flowers on the visits 

 of insects with its bearing on their evolution. Most of 

 the results of this work favor the negative of this question, 

 but nearly all of these investigators agree that insects have 

 color vision, although their evidence is far from conclusive. 

 With reference to reaction to color, none of the work of any 



