In the figures before alluded to may be seen the double visual apparatus with which bees are provided. The oval lobes on each side of the head represent the two eyes, the secondary organs of vision being the three small eyes on the top of the head, called "stemmata." We shall first describe the two larger eyes, which, as seems to be the case with all insects, are immovable, and have neither irides nor pupils, nor yet eyelids to cover them, but are protected from the dust or pollen of flowers by a number of small hairs, as well as by a horny tunicle, which defends and secures them from injury. The multitude of hexagonal lenses, called "ocelli," which make up the eye of a bee, give it, when viewed through a microscope, the appearance of honeycomb; or we might compare it to a multiplying-glass with hexahedral facets, each facet representing the surface of one ocellus. But when we look also to the inner structure, it resembles rather some thousands of telescopes all converging towards one point. It has been computed that in each eye there are 3,500 of these collateral lenses. Fig. 5 in Plate II. represents three of these prisms or lenses magnified. Each of them is wonderfully intricate in structure, comprising, first two plano-convex lenses of different densities, fitted together on the flat sides on the principle of an achromatic object-glass; next an empty space surrounded with dark pigment, which is convex within like the neck of a vase, so as to narrow the passage for the rays to about one-half the diameter, or one-fourth the superficial space; and lastly a longer conical lens, convex at each end and communicating with the optic nerve. The simple eyes, or stemmata, on the contrary, are as strictly simple as their name implies, consisting of one nearly globular lens apiece. The construction of the eye for seeing objects best at a moderate distance will account for the fact that bees mount high up into the air after collecting their store of food, and then, having determined the point, no matter how far off, they fly homewards with the directness of a cannon-ball, and alight at the door of their own habitation, though the country around may be crowded with hives; but on reaching the entrance their vision appears defective, for they then feel their way with the antennæ as if totally blind, and should the hive have been moved a little they will rise again into the air to obtain a more distant view, suited to the lengthened focus of their sight. When a stock or swarm is brought from a distance the bees do not take their departure at once, but reconnoitre awhile, visiting surrounding objects so as to well know the spot again in order to return thereto.