146 



AN INTRODUCTION TO ENTOMOLOGY 



structures of insects is a more or less peg-like rod contained in a tubular 

 nerve-ending (Fig. i6i, A and B); this nerv^e-ending may or may 



not be associated with a 

 specialized tympanum. 

 To all sense-organs char- 

 acterized by the presence 

 of these auditory pegs, 

 Graber ('82) applied the 

 term chordotonal organs or 

 fiddle-string-like organs. 

 The scolopale and 

 the scolopophore. — The 

 peg-like rod 

 characteris- 

 tic of a chor- 



Fig. 161. — Diagrammatic representation of the 

 auditory organs of a locustid (After Graber). 



dotonal organ of an insect was named by Graber the 

 scolopale; and to the tubular nerve-ending containing 

 the scolopale, he applied the term scolopophore. 



The integumental and the subintegumental scolopo- 

 phores. — With respect to their position there are two 

 types of scolopophores ; in one, the nerve-ending is 

 attached to the body-wall (Fig. 161, A); in the other, it 

 ends free in the body-cavity (Fig. 161, B). These two 

 types are designated respectively as integumental scolo- 

 pophores and subintegumental scolopophores. 



The structure of a scolopophore. — In a scolopophore 

 there can be distinguished an outer sheath (Fig. 161, I), 

 which appears to be continuous either with the basement 

 membrane of the hypodermis or with that of the 

 epithelium of a trachea, and within this sheath the 

 complicated nerve-ending; this nerve-ending is repre- 

 sented diagrammatically in Figure 161 from Graber and in 

 detail in Figure 162 from Hess ('17). 



In Figure 162 the following parts are represented: a 

 bipolar sense-cell (sc) with its nucleus (sen) ; the proximal 

 pole of this sense -cell is connected with the central nerv- 

 ous system by a nerve; and its distal pole is connected 

 with the scolopale (s) by an axis-fiber (a/) ; surrounding 

 the distal prolongation of the sense -cell and the scolopale 

 there is an enveloping or accessory cell (ec), in which 

 there is a prominent nucleus (ecn) ; distad of the enveloping cell is 



Fig. 162. — A 

 scolopo- 

 phore of the 

 i n t e g u - 

 mental type 

 (From 

 Hess). 



