472 ALFRED O. GROSS 



others. Loeb placed caterpillars of Porthesia chrysorrhoea under 

 a blue glass and noted that they oriented to the blue light in the 

 same way as when placed in white light. If, instead of the blue 

 glass, he used a red one the larvae remained indifferent. He 

 performed a number of varied experiments on this caterpillar 

 and repeated similar ones on moths of Sphinx euphorbiae and 

 Geometrica piniaria, plant lice, Musca larvae, larvae of Tenebrio 

 molitor and of the June-bug, Melolontha vulgaris, Limulus poly- 

 phemus, Polygordius and several species of copepods. In all 

 these experiments he used only two colors, red and blue, obtained 

 by means of screens. Loeb ('05, p. 182) concluded from the 

 results of his investigations that "The more refrangible rays of 

 the visible spectrum are exclusively or more effective, than the 

 less refrangible rays, in causing the orientation of the animals 

 as is also the case in plants." 



Plateau ('97, '99) following the work of Lubbock and Forel, 

 studied the behavior of the bees in an effort, to deterixiine whether, 

 the insects, in their visits to the flowers, were guided by the 

 different colors. Plateau, instead of using artificial colors, experi- 

 mented on natural flowers the colors of which, he thought, were 

 of equal brightness. He believed that bees are directed not by 

 color but by the sense of smell, a view in opposition to that 

 held by Lubbock and Forel. Plateau ('97, p. 41) concludes that 

 "lis (the insects) ne manifestent aucune preference ou antipathie 

 pour les couleurs diverses que peuvent presenter des fleurs des 

 differentes varieties d'une meme espece ou d'especes voisines." 



The view that bees are not directed to the flowers by the 

 different colors is also held by Bonnier ('79) and Bulman ('99). 



Yerkes ('99) majde a series of experiments upon the small 

 crustacean Simocephalus vetulus with spectral light. Wlien the 

 gas spectrum was thrown on a trough containing these animals, 

 the majority collected in the regions of the yellow and red light. 

 He then placed a prismatic glass box containing an India ink 

 solution between the trough and the spectrum. The greatest 

 depth of the solution was placed over the red and yellow so 

 that the intensity of this end of the spectrum was equal or less 

 than that of the blue and green region. Under these conditions 



