Eyes of Insects. 49 



pentine — a substance very repugnant to bees — to various parts 

 of a bee engrossed in sipping lioney. The bee made no objec- 

 tion, even tliough it touclied the ligula, until it approached 

 tlie mouth above tlio mentum, wlien slic became uaucli dis- 

 turbed. He also tilled a bee's mouth witli paste, which soon 

 hardened, after which the bee paid no heed to honey placed 

 near it. This was not so conclusive, as the bee may have been 

 so disturbed as to lose its appetite. I have experimented a 

 good deal, and am inclined to the following opinion: The 

 antennse are very delicate touch-organs or feelers, and are so 

 important in their function and connection that removal pro- 

 duces a severe shock, but further we know but little about 

 their function, if they have other, and from the very nature 

 of the problem we will find it very difficult of solution. 



The eyes are of two kinds, the compound, which are always 

 present in mature insects, and the ocelli or simple eyes, which 

 may or may not be present. When present there are usually 

 three, which, if joined by lines, will describe a triangle, in the 

 vertices of whose angles are the ocelli. Karely there are but 

 two ocelli, and very rarely but one. 



The simple eyes (Fig. 4,///) are circular, and possess a 

 cornea, lens, and retina, which receives the nerve of sight. 



From the experiments of Reaumur and Swammerdam, 

 which consisted in covering the eyes with varnish, they con- 

 cluded that vision with these simple eyes is very indistinct, 

 though by them the insect can distinguish light. Some have 

 thought that these simple eyes were for vision at slight dis- 

 tances. Larvae, like spiders and myriapods, have only simple 

 eyes. The compound eyes (Fig. 2, e) are simply a cluster of sim- 

 ple eyes, are situated one on either side of the head, and vary 

 much in form and size. Between or below these are inserted 

 the antennae. Sometimes these last are inserted in a notch of 

 the eyes, and in a few cases actually divide each eye into two 

 eyes. 



The eyes may meet above, as in drones (Fig. 4) and most 

 two-wing flies and dragon-flies, or they may be considerably 

 separated, as in the worker-bees (Fig. 5). The separate facets 

 or simple eyes, of each compound eye, are hexagonal, or six- 

 sided, and in the microscope look not unlike a section of honey- 

 comb. The number of these is prodigious — Leeuwenhoek 

 actually counted 12,000 in the eye of a dragon-fly, while some 



