Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/852

 HAR

thkkncfs of oik of the fmallcr fort of pins \ this lies flat up- tin the breaft and belly, reaching from the extremity of this piece to the infertion of the third pair of legs. This, how- ever fmall und delicate it appears, is not the trunk of the ani- mal, but is only the cafe or fheath of it, deftin'd to prefervc it from injuries. This is of a cartilaginous fubftance, and has a longitudinal fiflure running all along it which the crea- ture can ihut or open at pleafurc for the clofing up or exert- ing the trunk, which is an extremely tender and delicate long 'filament contained in it. The males among the Cicada only 6ng ; but this is a circumftance determined but lately, and that only among the more accurate obfervers. The an- tients and the country people at prefent m places where the ■C'taulcE are common, declare juft on the oppofite fide of the quefh'un, that it is only the females that fing ; and this is an error owing to the figure of the hinder part of the body of the female, which has been ufually taken as a character of the male: The fexes have been thus generally miftaken one {or the other ; and Malpighi acknowledges that lie was very near felling into it himfelf, having with the reft, of the world mif- taken the cylindric part at the extremity of the body of the female with which {he pierces the bodies in which me lays her eggs for the penis of the male, Reaumur's Hiit. Inf. vol. 9. p. 198.

It has been the common opinion, that the noife which the Cicada makes was occafioned by a fwift motion of the wings and their rubbing againft the bread, and the grating of the under pair of wings in their paflage againft the upper ones ; were this the cafe, there is no reafon why the female Cicada fhould not make this noife as well as the male, mice fhe has •wings and all the other requifites to fmging, according to thts fyftem i but in reality the matter is far otherwise, and the bare inflection of the body of the male Cicada will fhew that the noife is owing to other caufes. Jf we are deter- mined to call nothing a voice but the articulation of air thrown from the lungs in its paflage through the larynx and other parts, then the Cicada lias properly indeed no voice; but if we extend the meaning of the term farther, and take in the feveral founds made by infers in other manners yet intelligible to other infects, we muft allow the Cicada has a voice, and a very ftrong one, the organs of which are not in the lungs and throat, but in the belly.

On examining the belly of a large male Cicada there are found two large fcaly fpots very different from the reft of the fubftance of the rings ; thefe are not found in the female, and are of the fhape of the half of an oval cut through its fhorter axis, one fide of them terminating in a ftrait line, and the other part being rounded ; thefe are fixed without any articulation to the lower part of the lower corcelet or breaft, their ftrait edge being firmly united to it ; they are fo large that they meet in the middle of the belly, covering in part one another, and are fo long as to reach to the third ring at their rounded ends, if thefe pieces be railed with the point of a pin, and the part of the belly which is covered by them be nicety examined, there is found a very curious ftructure of the parts ; and there can remain no doubt but that thefe are the organizations deftin'd to ferve the male, in whom only they are found, to make that noife for which he is fo famous. Thefe are fo nicely formed that the ftructure of ■our own throats is not more admirable than that of the parts by which the Cicada makes its noife. There is a cavity form- ed in a very Angular manner in the anterior part of the belly of the creature : The hxft ring of the body is cut to form it, and the fecond is drawn back, and the upper part of this ca- vity is furrounded by a rim or edge much ftrongcr than the common matter of the rings of the body ; this cavity is rounded at the fides, and in the middle there runs up a fmall oblong membrane toward the head. The cavity is divided into two parts by a fcaly triangle of a convex figure, where it is in fight j the bafe of this triangle is at the breaft, and the apex runs to the belly, and meets the oblong membrane before- mentioned running under it. In the middle of the triangle there rifes alio a rib which runs to the membrane, '"and joins with it ; this raifes the triangle to a level with the reft of the belly. At the bottom of each of the cavities that the triangle divides the larger cavity into, there is feen a ■polith'd and refplendent part looking like a femicircle, the one edge of it being iixed to the triangle that divides the ca- vity, and the other following the round of the other parts of it. Thefe referable two pieces of extremely thin and tranf- parcnt glafs, or extremely fine flakes of talc, the fineft glafs or pureft talc not being more perfectly bright or tranfparent. When they are viewed iideways we perceive all the rainbow colours upon them. It feems as if the Cicada had two win- dows covered with the fineft glafs, by means of which we are able to look into the body and fee all that paffes there ; but thefe windows are generally clofed with a fort of mutters made by the fcaly piece w! L'h covers the whole cavity. We may eanly obferve, that the found or noife made by the £/-. cada comes from this cavity, and fball then eafity conceive that this fine membrane is only placed there to modify it. This found, the-' not agreeable to our ears, may pleafe the female, and chat is all that was intended by it, fince it is only to her that the male defires to fing. The piece which

HA R

covers the whole cavity is moved up and down in the mak- ing this noife ; but nature has provided a ligament to prevent its iifing too high, and a fupport to prevent its finking too low into the cavity of the belly. And finally there is a white membrane going from the anterior part of the cavity to the thorax. While many have fuppofed the noife made by the Cicada to be produced by the motion of its wings : Many others have been convinced that it was made by this part, becaufe none of the Cicada but thofe which have this organi- zation, that is, none but the males fing. Some have fuppofed that the rings of the body in bending it quickly backwards and forwards made the noife by their rubbing; againit the piece which covers the cavity, but it is eafy to be al- lured that this is not the cafe, fince in rubbing thefe ever fo brifely together by bending the body between the fingers there is no fuch noife made : Others have judg'd that the found proceeded from the fine tranfparent membrane that lies extended at the bottom of each cavity, but there is no finding the pieces which they fuppofe to ftrike upon this mem- brane : Finally, others fuppofe it to arife from the bending and again extending of the membrane, which goes from the lower edge of the cavity to the thorax ; but it is eafy to find alfo upon tryal, that the bending and unfolding of this by mov- ing the body in different directions between the fingers makes little or no found. When the upper rings of the back are taken off, there are kzn two extremely large and ftrong mufcles running from the corcelet toward the belly, and meeting in an angle at the extremities. It is wholly by the motion which this ftrong muicle puts the parts contained in the cavity into, that the noife of the Cicada is produced ; and even after the creature is dead and dry if this mufcle on either fide be railed a little with a pin, and then fuffer'd to fall back into its place, it makes the parts in fome fort per- form their motions j and there is the fame noife produced that the Cicada makes while living, only that it is more faint. The parts deftin'd to the making this noife are not all con- tain'd in the cavity above defcribed, but there is a triangular eminence on the nrft ring of the body, on each fide in the male, which the females have not ; this covers a part of the mechanifm of this found, and this may be eafily railed with. the point of a knife, without hurting the part within ; there is then found under this one of the principal organs of the found. This is a membrane of a very rigid nature, always form'd into feveral folds and wrinkles, and which when ft ruck upon yields a found like that of parchment when ftruck upon. When we draw over this membrane a piece of paper rolled up, or any other foft body that is not able to hurt it, we find it immediately make a noife which is owing to the bending inwards of fome parts of it which ftood convex by means of the folds, and their immediately throwing themfelves out again in the manner of a piece of ftiff parchment, or any the like fubftance. The found that we thus make is produced by the making fome parts of the membrane con- cave which were before convex, and then fufftring them to return to their former convexity, by means of their own ela- fticity. This is eafily performed in very quick times by the long and ftrong mufcles before defcribed ; each of thefe is placed behind or on the concave fide of one of thefe folded and fonorous membranes. Its fibres are all faftned into one or other part of this membrane, and it is very plain from hence, that the contraction of this mufcle muft pull in the whole convex furface and render it concave by drawing the convexity to its fide, and the remiflion of the action of this mufcle muft let the whole return into its former ftate ; this when done fuddenly cannot be done without the noife that we have before defcribed. The mufcles are capable of a verv fwift contraction and dilatation of this kind, and to that is owing the repeated noife of this membrane in unfolding k- felf, which makes the found of this creature. Reaumur's Hift.Inf. v. 9. p. 218.

The antients have obferved that the tettigorua or fmall Cica- da did not fing fo well as the large, and this is plainly ex- plain'd by the ftructure of this membrane, which in the mid- dle and fmall kinds is longer than in the larger ones, and is carried up under the firft ring of the body, and cannot be acted upon fo ftrongly by the mufcles which are the origin of the found. The tranfparent membrane at the bottom of each of the cavities is alfo much (mailer in proportion to the fize of the body in the little Cicada than in the great one ; and the whole ftructure of the parts mews, that tho' the- membrane which caufes the found be in thefe proportionably as large as in the male, yet all the other parts are lefs quali- fied to act upon it, and to nufe the found 3 the mufcles are placed in thefe, juft as in the great kind. Tho' the female Cicada wants the organs of finging of the male, fhe has however a part in her body which the male has not, and which deferves a peculiar attention. The eggs of the Cicada muft be lodged in the fubftance of wood, in or- der to their happily fucceeding in the hatching, and the in- ftrument of the female is intended for the purpofe of lodging them properly. The creature makes long cavities in the wood, and in thefe places her eggs in the moft nice order imaginable ; and the inftrument, by means of which file does this, is larger and more remarkable than that of any other 8 infeft