EYES OF INSECTS. 81 



the child judges only by analogy of position and of form, 

 dissection and experiment have alike induced the natural 

 philosopher to assign the name and office of eyes to those large, 

 brown, reticulated bodies, which in the said Fly or Drone-bee 

 are seen occupying th,e greater portion of the head. Besides 

 these, the same insects, and most others, are provided with 

 three smaller eyes, termed ocelli, which resemble shining 

 points, and which are usually placed in the form of a triangle, 

 above and between the larger pair. 



We find, therefore, that, both as respects the size and number 

 of their visual organs, Insects have greatly the advantage over 

 all other animals at present known, amongst which there is 

 not one which can boast of five, much less of eight eyes, or of 

 twenty, the complement bestowed upon the Spider and the 

 Centipede. 



We are by no means, however, to set it down for granted, 

 on this account, that every insect is a little eagle or Argus in 

 power and quickness of vision ; for their many eyes would 

 sometimes seem to serve them like the hare's " many friends/' 

 or like the many servants by whom we are often worse waited 

 on than by a few. All that we can pronounce on with any 

 certainty is this that the gift of sight, as well as of every 

 other sense conferred on insects, is adequate to the exigences 

 of their nature : for the rest, the closest observers are much at 

 variance. 



One of the most curious peculiarities observable in insect 

 eyes, in those of them, at least, which are large and conspi- 

 cuous, is their compound construction. Their cornea (or 

 outer coat) instead of being smooth, is numerously divided 

 into what are called facets, each of itself a little perfect eye. 

 Of these, a Butterfly has been assigned, in each compound 

 organ, 17,335 a Dragon Fly, 12,544 a House Fly, 7000. 



Possessing such a multitude of eyes or eyelets under one, it 

 might seem that of every single object Insects must be pre- 

 sented with a multitude of images. This, however, we have 



