AUDITORY SENSE OF HONEY-BEE 



191 



of cross-sections it may be seen to arise merely as a nerve 

 attached to the hypodermis; then the nerve suddenly runs to a 

 few large cells (fig. 15); a few sections further on the nerve dis- 

 appears, and the organ assumes a spherical shape (fig. 16, 0), 

 and the walls are fined with a thick layer of large cells, leaving 

 a cavity in the center, which is apparently filled with a fiquid 

 (probably only blood). 



Figs. 14 to 18 Sections, showing structure of tibial sense organs. Figs. 14 

 and 17, each a semidiagrammatic drawing from two consecutive longitudinal 

 sections of hind tibia of a drone, showing relative position of tactile hairs (THr), 

 olfactory pores (Por), chordotonal organ (0), and ganglion cells (G), all of which 

 are innervated by the same nerve (N, too wide here), although a small branch 

 of this nerve, called the subgenual nerve {SN) runs directly to the chordotonal 

 organ; fig. 14, X 32, and fig. 17, X 53. Figs. 15, 16, and 18, cross-sections through 

 tibia of a worker, showing relative position and shape of chordotonal organ (0) 

 and ganglion cells ((?); X 53; fig. 15, through proximal end of group of ganglion 

 cells. Af apodeme; Bj blood chamber; F, fat cell; Hyp, hypodermis; M, muscle; 

 N, two main branches of nerve; Tr, trachea. 



Using Schon's terminology, the detailed description of a single 

 chordotonal organ is as follows. The tibial nerve after im- 

 mediately emerging from the femur is apparently divided into 

 two large branches, because in all of the cross-sections made 

 two comparatively large nerves (figs. 15, 16, and 18, N) were 

 found. A short distance from the femorotibial articulation one 



