70 SUPPLEMENT ON 



excited, their respiration becomes more active, and they sud- 

 denly develope a temperature, which rises to two or three 

 degrees above that which they had at first exhibited. 



We shall here speak respecting the voice of insects, al- 

 though in reality the sounds produced by these animals can- 

 not always be attributed to the air which proceeds from their 

 bodies. When we come to speak of the hummmg of bees, 

 we shall notice some interesting facts on that subject. Most 

 of the noises produced by insects are owing to rapid vibra- 

 tions, communicated either to neighbouring bodies, or to 

 certain parts so conformed, as to represent cords or mem- 

 branes ; accordingly it has been said in speaking of insects 

 — Animalia muta, nisi alio proprio instrumento, sonora. 

 Some of them move the head against the corslet, or the 

 latter over the elytra, and thus produce a sound ; others 

 cause the rings of the abdomen to vibrate against the free 

 extremity of the elytra ; some are provided with a pencil of 

 stiff hairs, which operate like a brush rubbing against a solid 

 body — this is the case with the blcqis ; others strike with 

 force the wood which they are gnawing, with some part of the 

 head. The male cigala lias a sort of drum or concave scale, 

 under which rolls a cylinder furnished with projecting cords. 

 These last, as well as the males of locusts, crickets, &c., 

 cause some parts of their elytra to resound by crossing them 

 rapidly, or agitating them with the legs, as the cords of 

 certain instruments resound under the bow which is drawn 

 over them. This is a very interesting subject, and one 

 which we shall treat with more detail in the sequel. 



It now remains for us to speak a word on the most impor- 

 tant function of these animals : that by which they reproduce 

 their like, and the species are preserved. 



All insects proceed from other individuals absolutely simi- 

 lar to themselves, and from which they are separated at first 

 in the form of eggs : that is to say, the germ has been depo- 



