ORGANS OF GENERATION. 



vary much in their form, being sometimes elon- 

 gated, tortuous, convoluted, or ventricose, or at 

 others short and straight. The seminal vesicles are 

 generally two in number, even in those Lepi- 

 doptera in which the testis is single. In some 

 insects, as Tenebrio molitor and Hydrophilus 

 j>iccus, there are four; in others, as Dytucut 

 rnarginalis, six ; and in Locusta and Blatta, 

 they are very numerous. In some insects these 

 tubes are found to be of surprising length; 

 thus in On/ctes nasicurnis they are twenty 

 times as long as the body, and in Cetonia aurata 

 even sixty times the length of the animal. The 

 vasa deferentia and vesiculae seminales ulti- 

 mately terminate in one common tube, the ca- 

 nal is excretorius, which communicates with the 

 root of the penis; this canal is composed of 

 muscular walls largely supplied with tracheal 

 vessels, serving as a receptacle for the genital 

 secretions, and no doubt is the agent by which, 

 during coition, their expulsion is effected. The 

 penis of insects is a hollow tube, capable of 

 being protruded from the anal extremity of the 

 body : its texture is generally membranous, 

 but sometimes horny, and its shape exhibits 

 considerable variety ; it is usually cylindrical 

 or nearly so, becoming more slender towards 

 its termination. In Chermis pyms, however, 

 the end is enlarged ; in the common wasp 

 it is spoon-shaped; in Crabro bilobed, and in 

 some l"csp<e curved and bifid at its extremity. 

 In Musca vivipara its apex is covered with 

 spines ; in Tyrophaga putris and some other 

 Muscidae it is spiral. The penis of Coleoptera 

 is furnished with a bivalve sheath, destined to 

 open the vulva of the female prior to its inser- 

 tion. In some Diptera (Muscidae) a remark- 

 able inversion of the usual arrangement of the 

 organs of copulation is observable ; in these the 

 females are provided with a retractile penis, 

 whilst in the males the generative apparatus 

 terminates by a simple aperture. During coi- 

 tion in this case, it is the penis of the female 

 which is introduced into the genital opening of 

 the male, and thus becomes the recipient of the 

 fecundating fluid. The Dragon-flies (Libel- 

 lula) are remarkable from the position which 

 the male organ is found to occupy, being placed 

 under the anterior part of the elongated abdo- 

 men, but in the female the sexual aperture 

 occupies the usual situation near the anus. 

 This arrangement accounts for the singular 

 position which these insects assume during 

 copulation. 



In addition to the organs above enumerated 

 as composing the male system in insects, we 

 may notice appendages which are found in 

 some tribes which materially assist in effecting 

 the intercourse of the sexes : these are named 

 prehensores, and serve to seize and secure the 

 female during coitus. These holders assume a 

 great variety of shapes, and likewise are diffe- 

 rently disposed according to circumstances. 

 They generally surround the aperture through 

 which the penis is extruded, but in Libellula 

 the mode in which the sexes embrace each 

 other renders additional security indispensable; 

 in tins tribe, therefore, besides the anal prchcn- 

 sores, an additional pair of forceps is placed 



under the second abdominal segment. The 

 prehensores are generally two in number ; but 

 in many Lepidoptera, Conopis and Libellula, 

 three are placed around the anus. In Culex 

 there are two pairs. In Locusta morbUluste 

 there are five, and in Formica six holders. In 

 some tribes, as Megachilis, Agrionidas, and 

 Locusta, they are retracted within the abdomen 

 when not employed. 



In insects the ovigerous or female generative 

 apparatus consists likewise essentially of tubes 

 or cceca, the arrangement of which is tolerably 

 uniform. They may be divided into the ovaria, 

 the oviducts, the spermotheca, or receptacle 

 for the seminal fluid of the male, the accessory 

 glands, and the ovipositor, which latter is, in 

 many insects, an instrument adapted to intro- 

 duce the eggs at the period of their extrusion 

 into situations suited to their developement. 



The ovaria are double throughout the whole 

 class, each being composed of a variable num- 

 ber of membranous tubes arising from the 

 oviduct. Rifferschweils considers the ovaries 

 to be formed upon two primary types, being 

 either Jlagelliform, that is, composed of conical 

 tubes of equal length, which are inserted at the 

 same place at the extremity of the oviduct, as 

 in the Lepidoptera, the Bee, &c. ; or racemose, 

 consisting of short conical tubes, so proceeding 

 from the primary branches as to render the 

 ovary racemose or pinnated, such as they are 

 in many Neuroptera, Coleoptera, and Diptera. 

 The number of tubes composing each ovary 

 varies in different genera and species ; some- 

 times there are but two, at others four, five, 

 six, eight, or twelve, and in the more prolific 

 insects this number is much increased ; thus, in 

 Acrida viridissima there are thirty, and in the 

 hive-bee not fewer than a hundred and fifty 

 crcca in each ovarian packet. The number of 

 eggs will of course depend upon the number 

 and divisions of these ovarian tubes, and thus 

 while some insects only lay two, four, or six 

 eggs, others will produce sixty or seventy, arid 

 some gregarious insects a much greater num- 

 ber : thus the hive-bee will probably give birth 

 to many thousand young> and in the Termite 

 ant (Termes bellicosus) the fecundity of the 

 female is absolutely incalculable. This extra- 

 ordinary fertility renders indispensable certain 

 restrictions which we find imposed upon this 

 numerous class, tending materially to limit 

 their exce-sive multiplication. Thus, through^ 

 out the whole race one generation only is pro- 

 duced from the same insect, the business of 

 reproduction being usually the termination of 

 its existence ; and in the most prolific tribes, 

 namely, those which live in society, as the Bee 

 and the Termite, one female only in each com- 

 munity is found to be fertile, the sexual organs 

 of all the rest remaining in a rudimentary or 

 undeveloped state, although capable of de- 

 velopement, should the destruction of the 

 queen render such a provision for the preserva- 

 tion of the race indispensably necessary. (See 

 IXSECTA.) 



The uviductus or excretory canal common 

 to the ovarian tubes of the corresponding side 

 of the body, sometimes opens into the cloaca. 



