106 THE INSECT WOELD. 



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 scaly 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 in an upright position. 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 struck with the size of the two muscles which 

 meet and are attached to the back of the scaly 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 discover}?- 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 abutted." 



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

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

 partments, two cells in which are placed the instrument of sound. 

 This is a membrane in the shape of a kettledrum, not smooth, 



