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; 11th, 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 lie on the 
ventral surface of the antenna. 
Viewed superficially with transmitted light, a pore plate (fig. 
13, P) is seen to consist of an elliptical light 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 (6) 
being dark. A section through this organ shows that the hard 
and thick plate (figs. 9 and 18, P) is suspended on a membrane 
(m), resembling 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, 
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 appara- 
