VISION IN INSECTS, 



127 



The three small eyes on the upper part of the head and between the an- 

 tennae and the two large facetted eyes of the bee. a, worker bee ; b, male. 



externally formed exactly in the same manner, and 

 are smooth, glittering, and without divisions, and are 

 as much dispersed as those that are disposed at ran- 

 dom over the body. The wolf-spider (Salticus 

 sceniciis ?) which catches its prey by leaping on it, has 

 its eyes placed in the same manner *." 



Indep-endently, however, of the anatomical struc- 

 ture, of which from the minuteness of the parts there 

 might be considerable doubt, the experiments of 

 Reaumur appear to settle the point. " I have var- 

 nished those eyes," he says, " or what amounts to the 

 same, I varnished the back part of the head in more 

 than twenty bees, which I then set at liberty, three 

 or four paces from the hive ; but not one of them 

 knew where to find it again, nor appeared to search 

 for it. They flew at random towards the adjacent 

 plants, but never to a distance, and though they 

 seemed to have no difficulty in flying, I never saw 

 them rise in the air as those do whose facetted eyes 

 I had varnished overt-" The latter observation 

 seems to prove, that the coronet-eyes (stemmata^ 

 Linn.) are appropriated to upward vision; while we 

 may suppose the facetted eyes (pcidi) to be for hori- 

 zontal vision, and for looking downwards. Kirby, 

 indeed, has distinguished a whole genus (Tetrops) 

 * Biblia NaturiC; i. 214. f Meraoires; v. 289. 



