THE FLY. 37 



they have discovered food ; and to suppose that they 

 do this by means of signs caused by sound, would be 

 attributing to them a power of imparting information 

 that coidd hardly be regarded as the result of instinct. 

 The discovery by one of the authors* of this little 

 treatise, of the existence of sacs behind the delicate 

 membrane covering the pores, and also of the larger 

 apertures already alluded to at the base of the third 

 joint, may probably throw fresh light upon the 

 nature of the antennse. Meanwhile, however, we 

 must continue to regard the question of their function 

 as still \m§ettled, and content ourselves with obser- 

 ving that they possess some sensory function besides 

 that of touch ; either smeU, hearing, or both f. 



If the antennse of the Fly have proved a mystery to 

 naturalists, equally so have its wonderful eyes been 

 the subjects of speculative inquiry. These are five in 

 number, two being compound, and of comparatively 

 enormous proportions ; for they monopolize the greater 

 part of the head, from each side of which they pro- 

 trude in a semi-globular form (PI. IV. fig. \,bb). 



* Dr. J. B. Hicks : see Transactions of the Linnean Society, 

 vol. xxii. p. 147, in which he describes the bleaching process, 

 and similar organs to those named, in other insects. 



t The sense of hearing has been assig-ned to them by Bur- 

 meister, Carus, Strauss-Duikheim, Oken, Robineau, Desvoidy, 

 and Newport ; that of smell, or smell and touch, by Reaumm-, 

 Lyonnais, and several French anatomists, Kiister, Brichson, and 

 Vogt. 



It appears to us, that if insects, whose sensibility to external 

 influence is known to be acute, were confined and watched, 

 fresh light would be thrown upon the nature of their antennae. 



