292 Animal Life and Intelligence. 



brought a bee to some honey which I placed on a slip of 

 glass laid on blue paper, and about three feet off I placed 

 a similar drop of honey on orange paper. With a drop of 

 honey before her a bee takes two or three minutes to fill 

 herself, then flies away, stores up the honey, and returns 

 for more. My hives were about two hundred yards from 

 the window, and the bees were absent about three minutes 

 or even less. After the bee had returned twice, I transposed 

 the papers ; but she returned to the honey on the blue 

 paper. I allowed her to continue this for some time, and 

 then again transposed the papers. She returned to the 

 old spot, and was just going to alight, when she observed 

 the change of colour, pulled herself up, and without a 

 moment's hesitation darted off to the blue. No one who 

 saw her at that moment could have the slightest doubt 

 about her perceiving the difference between the two 

 colours." 



Passing now to the Crustacea, we find in them eyes of 

 the same type as in insects ; but in the higher Crustacea 

 ocelli are absent. In the crabs and lobsters the eyes are 

 seated on little movable pedestals ; in the former the 

 crystalline cones are very long, in the latter they are short. 

 There can be little doubt that vision is by no means want- 

 ing in acuteness in an animal which, like the lobster, can 

 dart into a small hole in the rocks with unerring aim from 

 a considerable distance. The experiments of Sir John 

 Lubbock have shown that the little water-flea {Daphnia) can 

 distinguish differences of colour, yellows and greens being 

 preferred to blues or reds. 



Among the molluscs there are great differences in the 

 power of sight. Most bivalves, like the mussel, are blind. 

 Interesting stages in the development of the eye may be 

 seen in such forms as the limpet, Trochus and Murex. The 

 limpet has simply an optic pit, the Trochus a pit nearly 

 closed at the orifice and filled with a vitreous mass, and 

 the Murex a spherical organ completely closed in with a 

 definite lens. The snail has a well-developed eye on the 

 hinder and longer horn or tentacle. But it does not seem 



