80 



THE PHYSIOLOGY OF INSECT SENSES 



Fig. 55. Tympanic organ of the prothoracic leg of Orthoptera. Ta, anterior 

 trachea; Tp, posterior trachea; Sb, subgenual organ; I, intermediate 

 organ; A, acoustic organ; SbN, subgenual nerve; TmN, tympanic 

 nerve; C, cap cells, S, scolopoid cells. (Redrawn from Schwabe, 1906.) 



(analogous to the Eustachean tube), whose spiracle lies at the anterior 

 border of the tympanum. The tympanum is in fact lined by two layers 

 of epithelium, that of the hypodermis and that of the tracheal sac, and 

 is bordered by air on both surfaces. 



The tympanal nerve, a branch of the tergal nerve of the third thor- 

 acic ganglion, enters the region in a fold of the tracheal epithelium, 

 branches, and attaches at several points of the drum (Fig. 54) : the 

 folded body (rinnenformiges Korperchen), the styliform body (stiel- 



