122 



SIE JOHN LUBBOCK ON ANTS, BEES, AND WASPS. 



that he only suggests this ex]3laijation. The facts he mentions 

 are very interesting, and it is to be hoped that he will continue 

 his observations. 



On the Colour- sense of Ants. 



Prof. Graber* has published an interesting memoir on this 

 subject. He confirms my observations on ants and Daphnias, in 

 which I showed that they are sensitive to the ultra-violet rays, 

 by similar observations on earthworms, newts, &c. It is inter- 

 esting, moreover, that the species examined by him sliowed 

 themselves, like the ants, especially sensitive to the blue, violet, 

 and ultra-violet rays. Prof. Graber, however, states that he 

 differs from m.e, inasmuch as I attributed the sensitiveness to the 

 ultra-violet rays exclusively to vision ; that it is " ausschliesslich 

 durch die Augen vermittelt." I would not, however, express that 

 opinion as applying absolutely to all animals, though it is, I 

 believe, true of ants, where the opacity of the chitine renders it 

 unlikely that the light would be perceived except by the medium 

 of the eyes and ocelli. 



Graber has demonstrated in earthworms and newts, and Plateau 

 in certain Myriapodsf, that these animals perceive the difference 

 between light and darkness by the general surface of the skin. 

 But more than this, Graber appears to have demonstrated that 

 earthworms and newts distinguish not only between light of 

 different intensities, but also between rays of difiterent wave- 

 lengths, preferring red to blue or green and green to blue. He 

 found, moreover, as I did, that they are sensitive to the ultra- 

 violet rays. Earthworms, of course, have no eyes, but thinking 

 that the light might perhaps act directly on the cephalic ganglia, 

 Graber decapitated a certain number, and found that the light 

 still acted on them in the same manner, though the differences 

 were not so marked. He also covered over the eyes of newts, 

 and found that the same held good with them. Hence he con- 

 cludes that the general surface of the skin is sensitive to light. 



These results are certainly curious and interesting ; but, 

 even if we admit the absolute correctness of his deductions, 

 I do not see that they are in opposition to those at which 

 I had arrived. My main conclusions were that ants, Daphnias, 



* " Fundamental Versuche iiber die Helligkeits- und Farben Empflndlich- 

 keit augenloser und geblendeter Thiere," Sitz. Kais. Akad. der Wiss. Wien, 1883. 

 t Journ. (\c I'Anatomie ot do la Plijsiologie, 1886, p. 431. 



