110 EVENINGS AT THE MICROSCOPE 



membranes, and the central portions, with their cavities, 

 all assist in it. In the cavity last described, if you remove 

 the lateral part of the first dorsal segment of the abdomen, 

 you will discover a semiopaque and nearly semicircular 

 concavo-convex membrane with transverse folds; this is 

 the drum. Each bundle of muscles, before mentioned, is 

 terminated by a tendinous plate nearly circular, from which 

 issues several little tendons that, forming a thread, pass 

 through an aperture in the horny piece that supports the 

 drum and are attached to its under or concave surface. 

 Thus the bundle of muscles, being alternately and briskly 

 relaxed and contracted, will by its play draw in and let 

 out the drum: so that its convex surface being thus ren- 

 dered concave when pulled in, when let out a sound will 

 be produced by the effort to recover its convexity; which, 

 striking upon the mirror and other membranes before it 

 escapes from under the operculum, will be modulated and 

 augmented by them. I should imagine that the muscular 

 bundles are extended and contracted by the alternate ap- 

 proach and recession of the trunk and abdomen to and 

 from each other. 



"And now, my friend, fl adds the excellent author, 

 "what adorable wisdom, what consummate art and skill 

 are displayed in the admirable contrivance and complex 

 structure of this wonderful, this unparalleled apparatus! 

 The great Creator has placed in these insects an organ for 

 producing and emitting sounds, which in the intricacy of 

 its construction seems to resemble that which He has given 

 to man and the larger animals for receiving them. Here is 

 a cochlea, a meatus, and, as it would seem, more than one 

 tympanum!" 



In some instances the sounds of insects more nearly ap- 



