SIH J. LTJBBOOK ON ANTS, BEES, AND WASPS. 377 



eluding from the experience of two widely divergent species — Man 

 and Baphnia — that the limits of vision would be the same in all 

 cases. 



His words are : — 



A. " Tons les animaux voient les rayons spectraux que nous 

 voyons." 



B. " lis ne voient aucun de ceux que nous ne voyons pas." 



C. "Dans I'etendue de la region visible, les differences entre 

 les pouvoirs eclairants des differents rayons colories sont les 

 memes pour eux et pour nous." 



He adds, that " puisque les limites de visibilites semblent etre 

 les memes pour les animaux et pour nous, ne trouvons-nous pas 

 la une raison de plus pour supposer que le role des milieux de 

 I'cfiil est tout-a-fait secondaire, est que la visibilite tient a I'impres- 

 sionnabilite de I'appareil nerveux lui-mSme ? " 



Such a generalization would seem to rest on but a slight foun- 

 dation ; and I may add that I have made some experiments myself 

 on Daphnias which do not agree with those of M. Bert. I hope 

 on some future occasion to have the honour of laying them before 

 the Society. 



At any rate, it seems to me that the preceding evidence strongly 



indicates that ants perceive the ultra-violet rays. Now, as every 



ray of homogeneous light which we can perceive at all appears to 



us as a distinct colour, it seems probable that these ultra-violet 



rays must make themselves apparent to the ants as a distinct and 



separate colour (of which we can form no idea), but as unlike the 



rest as red is from yellow, or green from violet. The question 



also arises whether white light to these insects would differ from 



our white light in containing this additional colour. At any rate, 



as few of the colours in nature are pure colours, but almost all 



arise from the combination of rays of different wave-lengths, and 



as in such cases the visible resultant would be composed not only 



of the rays which we see, but of these and the ultra-violet, it 



would appear that the colours of objects and the general aspect of 



nature must present to them a very different appearance from 



what it does to us. 



Sense of Direction. 



In continuation of the experiments recorded in my last paper 



(Linnean Journ. vol. xv. p. 177), I caused to be constructed a 



circular table 18 inches in diameter, the arrangement of which was 



kindly devised for me by Mr. Francis G-alton. It consisted, as 



shown in figs. 1 and 2, of three concentric pieces — a central F G, 



