§ II.] HEAD AND ORGANS OF SENSATION. 89 



much flattened, as in Fig. 2 c*, which shows the side 

 view. In common with other creatures, the head con- 

 tains the inlet for nutrition, and is the seat of the 

 principal organs of sensation. 



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 multi- 

 tude of hexagonal lenses, called " ocelli," which make up 

 the eye of a bee, give it, when viewed through a micro- 

 scope, the appearance of honeycomb ; or we might com- 

 pare 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, com- 

 prising, first two plano-convex lenses of different densities, 

 fitted together on the flat sides on the principle of an 



