104 THE INSECT WORLD. 



" The bottom of each cell offtrs to children who catch the Cicada 

 a spectacle which amuses them, and which may be admired by men 

 who know how to make the best use of their reason. The children 

 think they see a little mirror of the thinnest and most transparent 

 glass, or that a little blade of the most beautiful talc is set in the 

 bottom of each of these little cells. That which one might see if 

 this were the case would in no way differ from what one actually 

 sees ; the membrane which is stretched out at the bottom of the cells 

 does not yield in transparency either to glass or to talc ; and if one 

 looks at it obliquely, one sees in it all the beautiful colours of the 

 rainbow. It seems as if the Cicada has two glazed windows through 

 which one can see into the interior of its body." 



The horny triangle of which we spoke above only separates in two 

 the lower part of the cavity. The upper part is filled by a white, 

 thin, but strong membrane. This membrane is only drawn tight 

 when the body of the Cicada is raised. But with all this, where is 

 the organ of song ? What parts produce the sound ? Reaumur will 

 enlighten us on this point. 



He opened the back of a Cicada, and laid bare the portion of the 

 interior which corresponds with the cavity where the mirrors are, and 

 was immediately stmck with the size of the two muscles which meet 

 and are attached to the back of the horny triangle, and to that one 

 of its angles from which start the sides which form the cavities in 

 which are both the mirrors. 



" Muscles of such strength, placed in the belly of the Cicada, and 

 in that part of the belly in which they are found, seem to be only so 

 placed in order that they may move quickly backwards and forwards 

 those parts which, being set in motion, produce the noise or song. 

 And indeed, whilst I was examining one of these muscles, in moving 

 it about gently with a pin, slightly displacing it, and then letting it 

 return to its proper place, it so happened that I made a Cicada that 

 had been dead for many months sing. The song, as might be 

 expected, was not loud ; but it was strong enough to lead me on to 

 the discovery of the part to which it was due. I had only to follow ' 

 the muscle I had been moving, to search for the part on which it t 

 abutted." 



In the large cavity, in which are the mirrors and the other parts 

 mentioned above, there are besides two equal and similar compart- 

 ments, two cells, in which are placed the instrument of sound. This 5 

 is a membrane in the shape of a kettledrum, not smooth, but, on the 

 contrary, crumpled and full of wrinkles (Fig, 79). When it is touched I 

 it is more sonorous than the driest parchment. If the furrows on its 



