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N. E. McINDOO 



A glance at figure 12 shows that the articular ^^^^^^ 

 sembles the head of a drum and that the knobs act chiefly ^ 

 sense-fiber attachments. It is evident, judging merely from 

 the structure of this organ, that gusts of wind and possibly weak 

 air currents would cause the articular membrane to vibrate, tnere- 

 by irritating the sense cells. This organ might also receive jar 



Fig. 12 Diagram, representing most of second antennal segment of worker 

 honey-bee in longitudinal section and in perspective and a small portion of third 

 segment in both cross and longitudinal section and in perspective, showing John- 

 ston's organ which consists of two large groups of sense cells {SC) whose nerve 

 fibers (NF) run into the two antennal nerves {N) and whose sense fibers (SF) 

 are attached to the knobs (K) in the articular membrane (ArtM). Two of the 

 knobs are cut lengthwise, showing the cone-shaped cavity which opens to the 

 exterior, while the other knobs are heavily shaded, indicating that they are 

 buried in the articular membrane. Tr, trachea; Hyp, hypodermis; Ch, hard 

 chitin; and Ch, soft, flexible strands of chitin which firmly bind second and 

 third segments together. 



