no 



EAR OF FLY. 



As long ago as 1764 Keller * observed that the base 

 of the curious club-like "halteres," or rudimentary 

 hind-wings of flies, "est garnie de poils tres courts, 

 ou la tige a le plus d'epaisseur pres du corps ; elle est 

 ^ inflexible, et presque garrotte par en 



haut de plusieurs nerfs ; en un mot, elle 

 est faite de maniere que Ton pent juger 

 par sa force par les dehors." This 

 observation remained unnoticed, and no 

 further description appears to have been 

 given of the organ until it was redis- 

 covered by Hicks in 1856, and more 

 fully described in 1857.t 



He found that though in the Diptera 

 (flies and gnats) the hind wings are 

 reduced to two minute, club-shaped 

 organs, they still receive a nerve which 

 is the largest in the insect, except that 

 which goes to the eyes. This proves 

 that they must serve some important 

 function, and renders it almost certain 

 that they are the seats of some sense. 

 He also found at the base of the halteres 

 a number of " vesicles," arranged in four 

 groups, and to each of which the nerve 

 sends a branch, though the mode of pre- 

 paration w^hicli he adopted did not 

 permit him to see the finer structure of the nerves, 

 which he figures as mere fine, hard lines. He describes 

 the " vesicles " as " thin, transparent, hemispherical, or 



Fig. 71.— One of the 

 halteres of a fly 

 (after Lowne). 



* " G eschiclite der gemeinen Stubcnfliege," 1764. I have not seen 

 the original, and quote from Hicks's paper, 

 t Transactions of the Linnean Society, vol. xvii. 



