90 EVENINGS AT THE MICEOSCOPE. 



sound, and its aperture is to the Cicada what our larynx is 

 to us. If these creatures are unable themselves to modu- 

 late their sounds, here are parts enough to do it for them : 

 for the mirrors, the membranes, and the central portions, 

 with their cavities, all assist in it. In the cavity last de- 

 scribed, if you remove the lateral part of the first dorsal 

 segment of the abdomen, you will discover a semi-opaque 

 and nearly semicircular concavo-convex membrane with 

 transverse folds ; this is the drum. Each bundle of mus- 

 cles, before mentioned, is terminated by a tendinous plate, 

 nearly circular, from which issue 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 con- 

 vex surface being thus rendered concave when pulled in, 

 when let out a sound will be produced by the effort to re- 

 cover its convexity ; which, striking upon the mirror and 

 other membranes before it escapes from under the oper- 

 culum, will be modulated and augmented by them. I 

 should imagine that the muscular bundles are extended 

 and contracted by the alternate approach and recession of 

 the trunk and abdomen to and from each other. 



" And now, my friend," 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 should seem, more 

 than one tympanum ! " 



In some instances the sounds of insects more nearly 

 approach the character of true voices ; at least so far as 



