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 (S) is the narrowest portion of the antenna. 

 When examining the extreme distal end of the second segment 

 under a low-power lens, a circle 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, K) from now on, he 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. 



Obhque 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 (S) 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 sohd black) of the articular membrane 

 (figs. 7 and 12, ArtM) is reenforced by a layer of soft, flexible 



