AUDITORY SENSE OF HONEY-BEE 181 
culex mosquito. This structure, later called Johnston’s organ, 
was thoroughly investigated by Child (94 a,b), who saw it in all 
the insect orders examined, except one. He found it in several 
genera of Diptera, one genus of Hymenoptera, and in one or more 
genera each of Coleoptera, Lepidoptera, Neuroptera, Pseudo- 
neuroptera, and Hemiptera (Homoptera). Apparently he did 
not examine the honey-bee, but found it in a wasp (Vespa vul- 
garis) well developed, although the articular membrane to which 
the sense cells are attached is not complicated as he found it in 
mosquitoes and as the present writer saw it in the honey-bee. 
Of the many specimens examined, Child found this organ most 
highly developed in the male mosquito (Comstock, ’20, pp. 
152-154, for a general description). He also saw sense organs in 
the second antennal segments of Orthoptera, but decided they 
were not Johnston’s organs. Recently these have been described 
as olfactory pores by the present writer (’20). 
The distal end of the second antennal segment (fig. 3, 2) is 
considerably larger than the proximal end, but the proximal end 
of the third segment (3) is the narrowest portion of the antenna. 
When examining the extreme distal end of the second segment 
under a low-power lens, a cirele of irregular structures (J), 
somewhat resembling a miniature mountain chain in shape, passes 
completely around the segment. Observing a crushed segment 
under a high-power lens, it will be noted that these structures, 
known as chitinous knobs (fig. 4, A.) from now on, lie in the ar- 
ticular membrane between the second and third segments. The 
top line in figure 4 represents the union of this membrane with 
the second segment, and the bottom line the union of the same 
membrane with the third segment. As an average for each caste, 
a worker has 70 of these knobs; a queen, 72, and a drone, 100. 
Oblique sections through the articular membrane show that it 
(figs. 5 and 6, ArtM) is very thin, that the ends of the knobs 
(K) fit into sockets GS) in the chitin (Ch) of the third segment, 
and that soft, flexible strands of chitin (figs. 6 and 12, Ch) 
firmly bind the two segments together. In fact, the hard, rigid 
chitin (represented by solid black) of the articular membrane 
(figs. 7 and 12, ArtM) is reenforced by a layer of soft, flexible 
