HOMING FACULTY. 217 



6tance of bees flying against a gable painted sky-blue that they had regu- 

 larly avoided before, and one of young bees issuing from a blue hive and 

 flying on their return to other blue ones by mistake, but never to those 

 painted in other colors. 



Vision in ants. — Fielde (1902:599), whose studies of vision in ants 

 were in agreement with those of Lubbock and Forel, stated that — 



"The ants manifested no liking for any of the rays of light. If obliged to stay in 

 light rays of some sort, the rays of longer wave-lengths are preferred to those of shorter 

 wave-lengths. Dividing the spectrum, as we know it, into red, green, and violet, 

 we may say that to the ants' eyes red and green are most like the darkness that they 

 prefer and that violet is to them most luminous; or that the red and green are less 

 visible to them than is violet. In this regard the eyes of the ant appear to be the re- 

 verse of our own. Our eyes perceive in the spectrum three fundamental colors — red, 

 green, and violet. The eyes of the ant perceive there only two fundamental colors — 

 one made up of the red and green rays, the other of the violet and ultra-violet rays. 



"It appears that the eye of the ant is not well adapted to the reception of light-rays 

 whose wave-length is longer than in the violet rays ; that it receives blue and indigo 

 more perfectly than red, orange, yellow, and green; and that there is a sudden in- 

 crease of luminosity in the light rays at that point in the spectrum where violet be- 

 gins for our eyes. The ants may discern colors, and yet have no preferences among 

 the colors discerned. Color is determined by the wave-length in the light-ray, and 

 since ants discriminate between rays of different wave-lengths, they probably perceive 

 color in the rays. Sensitivity to the length of the wave indicates perception of color." 



The role of ultra-violet in attraction. — Richtmyer (1922) has de- 

 termined the ultra-violet reflection of a number of Colorado flowers with 

 reference to a possible influence in attraction. He considers that the effect 

 of ultra-violet in attraction involves two questions: (1) do insects "see" 

 ultra-violet in the sense that they seem to "see" the rays visible to us? 

 (2) is the ultra-violet reflected by flowers present in sufficient degree to 

 play an important part in rendering flowers visible to insects? It was 

 found that few of the flowers reflected any considerable proportion of 

 ultra-violet, only 4 of the 25 studied reflecting more than 10 per cent of 

 radiation shorter than 0.38 wi. These were Laciniaria punctata, Oenothera 

 biennis, Rudbeckia laciniata, and Solanum rostratum. Certain yellow flow- 

 ers showed a distinct ultra-violet reflection band, particularly well marked 

 in Rudbeckia, but others such as Solidago and Ratibida gave no trace of 

 such a band. The flowers differed from each other in the reflection of ultra- 

 violet just as much and as erratically as in that of the visible spectrum. 

 It might be expected that a white flower, which reflects the visible rays 

 in approximately equal proportions, would also reflect a considerable 

 amount of ultra-violet, but this is not the case. They gave a high reflection 

 of light longer than 0.42 or 0.43 n, but none of them reflected more than 4 

 per cent of 0.39 /j.. The most striking case was that of Argemone platyceras, 

 with a relative coefficient of reflection of more than 75 per cent at 0.41 n 

 and of only 4 per cent at 0.39 ju. 



THE HOMING FACULTY IN BEES AND WASPS. 



Fabre's experiments with bees and wasps. — In his "Souvenirs Ento- 

 mologiques" (1879:299, 1882:99), Fabre recounted his studies of the horn- 



