AUDITORY SENSE OF HONEY-BEE 187 



of the drone. They are rather equally distributed over the 

 various segments. Using the average number of pore plates on 

 a worker antenna as an example, the segments and number of these 

 organs are: 5th, 322; 6th, 345; 7th, 332; 8th, 288; 9th, 284; 10th, 

 283; nth, 278, and 12th, 240. Twelve per cent of these lie on 

 the ventral surface and 88 per cent on the dorsal surface. Rela- 

 tive to the pore plates on the queen and drone, only 3 per cent 

 of those of the former and 25 per cent of the latter he on the 

 ventral surface of the antenna. 



Viewed superficially with transmitted hght, a pore plate (fig. 

 13, P) is seen to consist of an elliptical hght. spot, which is 

 surrounded by three concentric bands; the first and third ones 

 (a and c) being light in color, and the second or middle one (b) 

 being dark. A section through this organ shows that the hard 

 and thick plate (figs. 9 and 13, P) is suspended on a membrane 

 (m), resembhng a double hinge, which viewed by transmitted 

 light causes the above dark band (6), while an inner groove 

 (d) causes the first light band (a) and an outer groove (e) produces 

 the other light band (c). In reality this outer groove is not a 

 true groove, because its walls or sides lie against each other and 

 allow no cavity, except perhaps when the plate is vibrated. This 

 fact explains why other observers have overlooked it. Ruland 

 saw it in sections made from caustic potash material, which must 

 have been considerably distorted. The present writer has also 

 seen it many times in the same kind of sections, besides in other 

 sections made from material not treated with KOH. Any dark 

 stain obliterates this groove, and consequently the writer was 

 able to see it by using eosin alone. 



Judging from the structure of a pore plate, the elliptical plate 

 (fig. 13, P) may be moved in and out on the double hinge (m), 

 thereby moving the large nerve strand (St) and consequently 

 affecting the large sense cell group (SCG). These organs, there- 

 fore, might be an air-pressure apparatus, as suggested by Nagel 

 and Schenk. It has been observed by Schenk and the present 

 writer that bees, when flying toward an object, such as a window, 

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

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



