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ANNUAL REPORT SMITHSONIAN INSTITUTION, 1920. 



contract and relax very rapidly, thereby causing the axillaries to 

 vibrate; consequently the above membranes are caused to vibrate 

 rapidly, thus producing the piping, teeting, or squealing noise, com- 

 monly heard when a bee is squeezed. 



The pore plates, lying so abundantly on the antennae and called 

 olfactory organs by other authors, were found to have two grooves 

 (fig. 14, G) encircling each elliptical plate (P), thereby allowing the 



Figs. 14 and 15. — Schematic drawings of supposed ears or auditory 

 organs of honeybee. Fig. 14, portion of a pore plate from antenna in 

 section and in a superficial view, showing plate (P) supported by 

 a double hinge between two grooves (G), and the nerve (N) at- 

 tached to plate. Fig. 15, portion of a longitudinal section through 

 articular membrane (M) between second and third antennal seg- 

 ments, showing Johnston's organ, which consists of knobs (K), ex- 

 tending inward from membrane, to which nerves (N) are attached. 



plate to move in and out on a double hinge, as may be seen by look- 

 ing at figure 14. Judging from this mechanism, the function of 

 these organs might be interpreted in a new light. It is well known that 

 many insects, when flying swiftly toward an object such as a window, 

 light on their feet instead of butting their heads into the object. 

 Now, it may be that the pore plates act as an air-pressure apparatus, 

 in which capacity they inform the insects of the object immediately 



