VISION IN INSECTS. 123 



tice of bees flying, as Huber has stated, straight to 

 and from the hive, we have in numerous instances 

 seen a bee search the same blossom two or three times 

 in the course of a few minutes, in utter forgetfuhiess 

 of having ah'eady plundered it of its honey.* 



If Reaumur, however, be correct in his opinion, as 

 we are inclined to think he is, these apparent discre- 

 pancies may be easily reconciled ; for he attempts to 

 show, that bees and most other insects are endowed 

 with two sorts of eyes, one for distant, and another for 

 near vision ; instead of having the power as we have 

 of adapting the eye to various distances, the nature of 

 which adaptation is not well understood. | In order to 

 understand this more precisely, it will be necessary to 

 enter into a few details as to the number and structure 

 of the eyes of insects. 



It may at first appear not a little puzzling to con- 

 ceive how a spider with eight eyes, a centipede with 

 twenty, and a butterfly with thirty-five thousand 

 facets in its two eyes, can perceive only one object ; 

 yet the difficulty is not of a very different kind from 

 that of our own two eyes representing only a single 

 object and not two, — a subject which has exercised the 

 ingenuity of many a philosopher. Vandermonde,J 

 for example, supposed that children at first see 

 double, and correct the error by experience ; an 

 opinion adopted by Blumenbach : Dr Reid referred 

 it to an original and inexphcable law of human na- 

 ture, § confessing thereby his inability to explain it ; 

 and some of the old philosophers satisfied themselves 

 that it was because the nerve from each eye meets 



* J. R. 



t Des Cartes, IMariotte, Jurine, Dr T. Young, Mr C. Bell, 

 Mr Travers, &c, have given various opinions on this subject. 

 t Apud Haller, Physiol. 

 i Inquiry into the Human Mind. 



