The interesting observations of Sir John Lubbock seem to show that insects can distinguish between different colours. "Amongst other experiments," he says,[FK] "I 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 wanting 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 to be aware of the presence of an object until it is brought within a quarter of an inch or less of the tentacle. In all probability the eye does little more than enable the snail to distinguish between light and dark. And the same may be said of the eye of many of the molluscs. In some, however, the cuttle-fishes and their allies, the eye is so highly developed that it has been compared with that of the vertebrate. There is an iris with a contractile pupil. And the ganglion with which it is connected forms a large part of the so-called brain. The powers of accurate vision in these higher forms are probably considerable.