Auditory Organ in the Antenna 95 



inside also, are many articulated brancJies, wliicli are 

 connected with a regular and close-set layer of end- 

 organs (fig. 67). These resemble slender cones, with 

 the apex turned towards the peripheral fibres, and the 

 base away from them. By maceration in weak chromic 

 acid the articulated branches are resolved into their 

 elements, slender rods with two to three elongate nuclei 

 apiece. These elements are not closely connected, at 

 least in the hardened tissues from which sections are 

 cut. They are arranged in about three rather irregular, 

 concentric zones, and appear slightly separated from 

 the end-organs. Both the 

 articulated branches and 

 the end-organs appear to 

 be peculiar modifications of 

 epidermic cells, or of inter- 

 cellular substance secreted 

 by them. A deep circular 

 fold of epidermis may be 

 supposed to pass, during 

 the development of the fly, 



far into the interior of the , ^'«- 67- -Transverse section of en- 



larged second joint oi antenna ot male 

 enlaro-ed ioint. The cells Chironomus-fly, showing end-organs. 

 . X '50. 



give rise to the elongate 



elements of the articulated branches and end- organs, 

 which acquire a radiate arrangement, and the peri- 

 pheral fibres with their connecting sheet form in the 

 cavity of the fold. The outer (morphologically inner) 

 surface of the end -organs is connected by delicate fibres 

 with a ganglionic layer, and this in turn by a multitude 

 of fibres with the antennary nerve (fig. 66). A. much 

 smaller branch of the antennary nerve passes along the 

 centre of the antenna to the remaining joints. 



In the female fly the structure is similar, but far less 

 complex. Tanypus has almost the same antennal struc- 



