In arranging insects in your cabinet, if you wish to have it scientific, as much as the nature of the subject will admit, follow the series ofaffinities; but you may reserve a few drawers to place in contrastanalogousforms. As your numbers of species increase you will have to alter your arrangement; but as pencil lines are easily rubbed out, this will occasion you less trouble than if they were drawn with ink. You should always be careful under each genus to leave space for new species.
As certainAcarina,Tineidæ,Ptinidæ, &c., prey upondead insects, you will of course wish to know how they may be kept out of your drawers, or banished when detected there.Camphoris the general remedy recommended. The cavity closed by the rabbet of the glass frame affords a good receptacle for this necessary article: put some roughly powdered into each side, and be careful to renew it when evaporated. This will generally preserve your insects, as will be seen from the result of the following experiment.—Some insects in a chip box having become much infested by mites andPsocus pulsatorius, I placed under a wine-glass several of each along with roughly-powdered camphor: at the end of twenty-four hours the mites were alive; but at the end of forty-eight they were all apparently dead, and did not revive upon the removal of the camphor. The specimens ofPsocusall appeared dead in an hour, and never revived. If the camphor be put only into one side of a drawer, and in a lump, though perhaps it may keep out mites, &c., it will not expel them.
I am, &c.
An entomologist who aspires to more than the character of a mere amateur, will not be content with filling his cabinet with nameless objects for the sole amusement of the eye; but will also be anxious to acquire some knowledge of what he has collected, and to ascertain by whatnames, whether indicating their genus or species, they have been distinguished by scientific writers who have described insects either in general or those of particular districts. Thus only can he himself derive profit from any discoveries he may make, or contribute to the further progress of the science[1582].
But in order to accomplish this object effectually, you must remember and practise theOnslowmotto—Festina lente:—you must not be too eager to name yourspecies, but begin first withgroupingyour collection. The only way to acquire, in any degree, a correct knowledge of the Natural System, or of the general plan of theCreator, which is theprimumandultimumof true science, is by studyinggroups. The knowledge of species is indeed indispensable for the registry of facts and other practical purposes, but the knowledge of groups leadsto a higher wisdom; and indeed it is through these that we best descend to the study of species.
I will suppose you have made yourself master of so much of the technical language, particularly the names and most important attributes of the principal organs of insects, as will suffice for understanding descriptions, or knowing these parts when you see them. I will also further suppose that what was formerly said on these subjects has been sufficiently studied, to enable you without much difficulty or hesitation to say whether any given object belongs to the ClassInsectaorArachnida, or to which of their respective Orders[1583]. You are therefore qualified to arrange your collection into itsprimarygroups. But you have seen that manyothersintervene between the Order and the genus or species. As thegeneraof Linné are mostly primary groups of Orders, perhaps, setting aside such insects included in them by him as your eye and their apparent characters convince you have no claim to a place there, your next best step would be to make yourself thoroughly acquainted with them. When you have accurately marshalled and intimately studied these groups, you will probably have acquired an eye and a tact,experto crede, for grouping without book, and may proceed by analysis to resolve your whole collection, as nearly as possible, into as many as nature seems to indicate to you. In doing this you will doubtless at first fall into many errors; but these, practice and a closer examination will in time enable you to rectify. Having thus got your groups as near to nature as you can, you may now have recourse to thoseauthors, particularly Fabricius and Latreille, who have subdivided the genera of Linné; and you will see which of your groups agree with theirs, detect your own errors, and often theirs, and be enabled to label each of your genera and higher groups, if already known, with its modern appellation. You are now qualified also to enter scientifically into the study of thecharactersthat distinguish groups, and may proceed, wherever opportunity is afforded, to examine thetrophi, which may often be displayed sufficiently by the means recommended in my last letter[1584]. In this way you may learn also to know your groups as well by character as by habit, and be qualified to trace the gradual progress of nature from form to form; and may look upon yourself as duly prepared to put the last hand to your labours, and proceed to the examination ofspecies.
It will have occurred to you, in making out your genera orlowestgroups, that some consist of a vastly greater number of species than others. It seems advisable therefore, when you apply yourself seriously to ascertain what described ones your cabinet contains, to begin with those genera which appear to be poor in them; for here your labour will be comparatively light, from the small number you will have to examine; and you will become practised in the employment before you are called upon to attack those that overflow. Had Fabricius and other describers of species taken the trouble to subdivide the larger groups, as might easily have been done, into moregeneraandsubgenera, the student would have been spared a most discouraging labour. To be obligedto compare a single individual with the descriptions of from 100 to 300 species[1585], to ascertain its name, seems enough to make you start aside with horror from the employment, and be content that your species should remain unnamed, rather than expose yourself to such a waste of time and patience. But to lessen your alarm and encourage you to proceed, I must observe to you, though in a few instances it may be necessary to advert to the description of every single species in a section, yet that this is seldom requisite; and where it is, there are many helps to diminish the labour and abridge the process. A large number of insects are characterized by theircolour; and it is the practice of all good describers to begin their definition of the species with that which predominates, and then to enumerate the variations from it. Thus, if an insect be allblackexcept thethorax,antennæ, andlegs, you will find it thus characterized, "Black:with thorax, antennæ, and legs ferruginous"; and so on. Hence, having noticed the predominant colour of your unknown species, in many genera you may compare it with the descriptions contained in a whole page at a single glance, and only read the further descriptions when the colour agrees. A practised Entomologist will thus investigate his insects with a rapidity which to an unlearned bystander would seem impossible. Though I have instancedcolouras being the character most commonly employed in describing species of insects, you will readily conceive that in some tribes other characters afford more prominent distinctions. Thus intheDynastidæand many other Petalocerous beetles, the principal specific character is derived from thehornsortuberclesthat arm the head and thorax: inLucanusfrom themandibulæ; and inPrionusfrom the marginalteethof the thorax. If the insect, then, you want to name belongs to any of these genera, having observed its peculiar characters in this respect, you may ascertain in a very few minutes whether any already described exhibit the same. This facility of investigation can be better acquired by practice than precept, and cannot be attained all at once. The above hints, however, may be of some use; and cannot fail to be so, if you always endeavour to make yourself acquainted by a previous careful examination with the characters of every new insect you acquire,—whether those of form, colour, or sculpture,—before you attempt to discover its name in Fabricius or any other author.
When you have made such proficiency in the study as to be familiar with a few species of each section of an extensive genus, the labour of investigation will sometimes be greatly facilitated by attending to that conformity between the proportions, general aspect, and figure of a known and an unknown insect, which Naturalists express by the name ofhabit, and which, though easily perceived by a practised eye, is described with such difficulty. Scientific Entomologists in their descriptions have usually taken care to place near to each other, species agreeing in habit. When therefore you know the name of one species, and find another of the same general habit, you may commonly take it for granted that if described at all by your author, it will be placed near that already known to you. Thus, supposingyou are acquainted with that common weevilCionus Scrophulariæ, and find its near relationC. Blattariæ; instead of comparing it one by one with the 161 species which compose theLongirostres femoribus dentatisof the Fabrician genusRhynchænusin theSystema Eleutheratorum, you would at once turn to the former, very near which you would without further trouble discover it. Fortunate, would it be, could the Entomologist always depend on thus finding descriptions of allied species in the neighbourhood of each other; but unhappily the most distinguished authors have sometimes violated this important rule, so that we cannot always be certain that any given species is not elsewhere described than in its right place. Fabricius in many instances often removes widely asunder insects not merely related, but which are in reality scarcely more than varieties of the same species[1586]. In fact, the attention of this celebrated author was so distracted by the immensity of the materials he had to arrange, by the distance of the cabinets, in many cases, from each other, the new species of which he undertook to describe, and the rapidity with which they necessarily passed under his eye, that he seems never to have attained any nice perception of theaffinitiesof insects.
You must not conclude, however, that the investigation of a new insect is even to an adept always a work of ease and dispatch. Often, when seemingly ascertained by the rapid process above indicated, a further inquirywill be requisite; the more detailed description must be read, and figures consulted, before its name can be indisputably determined. In addition to the difficulty arising from the insufficient characters frequently given by Fabricius and the older authors, obstacles arising from their errors not seldom intervene. Thus they have sometimes selected for aspecificcharacter,—as in the case ofMegachile centuncularis,Nomada ruficornis, and various other insects,—what really only indicates afamily. At other timessexualcharacters common to many,—as inEucera longicornis,Locusta perspicillata, &c.,—have been had recourse to. In these cases, in order satisfactorily to ascertain your species, you must further consult thesynonymsandhabitatgiven by the original describer, especially the figures he has referred to. When all these fail, as they sometimes will, thedernier resortis a reference to the cabinet containing the original specimen from which the description was drawn. British Entomologists possess an invaluable privilege, which their continental brethren may well envy them, in having the most liberal access, indulged to them by the learned President of the Linnean Society, to Linné's collection of insects, from which a large proportion of the species he described may be ascertained[1587]. Several of the cabinets, especially the Banksian,—now the property of the Linnean Society,—from which Fabricius described hisinsects, may also still be consulted; and thus many mistakes rectified, which would otherwise greatly mislead[1588].
Though sometimes the limits that separate good species appear at first very slight, and require a practised eye to catch them, yet it occasionally happens that considerable apparent differences may safely be disregarded. Thecolourof insects,—to which unhappily for want of better characters we are so generally forced to have recourse,—though usually constant, is in some species very variable[1589]. This is the case sometimes withwholecolours. ThusCarabus arvensis,Pœcilus cupreus, &c., are sometimes of a copper colour; at others, resemble brass; at others, they are green or blue, and even black. The colour ofspotsalso often varies. In some individuals ofPentatoma oleraceathey are pale, and in others red. The number and shape of spots are also often inconstant. Many of the species ofCoccinellaso abound in these variations, that nothing short of the most careful examination can enable you to distinguish the species from the variety. Insects vary also insize: but as this is never assumed as a specific character, it will not occasion you much trouble. Where the difference in this respect between two specimens is very great, the presumption is that they are specifically distinct. Differences insculptureandproportiondo not always indicate differentspecies; this being sometimes, as we have seenabove, only asexualcharacter[1590]. Authors also in their descriptions, in this respect sometimes mislead the young student. When Linné calls thethoraxofAphodius erraticussmooth (lævis) he would not expect to find it covered with impressed puncta, and with a longitudinal posterior impressed line. Likewise in describingChlænius vestitusandnigricornis, Fabricius passes without notice their punctate surface, so different from that of otherHarpalidæ. Errors of this kind however, it is but fair to observe, are chiefly to be attributed to the circumstance that both Linné and Fabricius rarely employed amicroscopein making descriptions; though no one now attempts this, except where insects are large, without such an aid.
If you ask, How am I to acquire this delicacy of tact which is to decide when the terms of a specific character are to be rigidly adhered to, and when taken with a certain latitude? I answer, In the same way in which a connoisseur attains the faculty of discerning the works of different masters in painting;—by such careful study of your author as will make you master of his style. Thus you will soon perceive in what cases expressions are to be taken literally and strictly, or with some allowance and abatement.
There yet remains more distinctly to be adverted to, the assistance that may be derived in the investigation of insects fromfigures. Generally speaking, these should never be referred to in the first instance, but be regarded as a resource when the ordinary methods leave the subject of inquiry doubtful. Those who begin theirentomological studies by turning over figures usually end them there, and never attain to that nameless tact in making out insects that can only be the result of patient study. Indeed figures, though often very useful, and sometimes indispensable, can scarcely ever exhibit those nice characters, particularly as to sculpture, that distinguish some insects. Our modern artists, indeed, are remedying this defect of the art, by giving in many cases the thorax or elytrum apart, with all its sculptural peculiarities: but this is not, and cannot be, done so as to represent every one. But though in general figures should be your last resort, I know not whether an exception to the rule may not be advisable with respect to theLepidoptera, which are more difficult to be intelligibly described than any other order of insects; while a good figure exhibits to the eye all those markings and shades, that scarcely any description can place clearly before the mind.
When every attempt to investigate the name of your unknown species fails, and you have consequently reason to believe that it is undescribed, the best mode you can pursue for retaining that knowledge of its characters, which from your long investigation you must have acquired, is to note them down in yourentomological journal, inserting it under its proper genus with a trivial name of your own. Such a journal you will find almost asine qua nonfor containing a catalogue of your insects, and to register any observations concerning individuals you may have had an opportunity of making. With regard to this journal, I should recommend to you to get two blank books. One a duodecimo of 200 or 300 pages, to contain the mere catalogue of your insects,their habitat and localities, or the source from which you derived them. In this you should number the genera in Roman capitals, and the species under each by a figure; leaving considerable space at the end of each genus for the insertion of new species. The other book should be of an octavo size, containing 400 or 500 pages. Under the number of each genus and species you might describe and figure it, if undescribed; if described, note in what it varies from the description, and what characters are overlooked: and in general, insert such observations, with regard to its economy and habits, as you may have had an opportunity of making.—As to foreign insects, wherever you can, upongoodauthority, be particular in indicating the country and station of each specimen.
I need not say much to you concerning the microscopes you should use for the examination of insects, a common pocket one of three glasses of different powers will answer every ordinary purpose[1591].
We have treated hitherto of insects as we find them now inhabiting our globe: but I must not conclude our correspondence without taking some notice of those that are found in afossilstate. Fossil insects may be divided into those that are found inamber, and those that are found inothersubstances.
It has been observed with respect to insectiferous amber, that the greater part of the insects found in it exist no longer in the countries that produce that amber, and that in every different locality the insects found in it aredifferent. Thus the amber of Sicily contains various species ofColeopteranot to be met with in other ambers, while that of the Baltic is rich inDipteraandNeuroptera[1592]. It is further observed, that the insects inclosed in the amber of Prussia, and those figured by Sendelius in hisHistoria Succinorum, all belong to genera at this time found in Europe[1593]. Insects of the following genera are recorded as having been found in this singular substance:Platypus,Elater,Atractocerus;Gryllus,Mantis; larvæ ofLepidoptera;Trichoptera;Ephemera,Perla,Termes;Formica;Tipula,Bibio,Empis;Scolopendra; and variousArachnida[1594]. In a piece of amber in my collection I findEvania,Formica,Chironomus, and someArachnida.
Fossil insects have also been found in other substances. Parkinson figures larvæ ofLibellulinafound in limestone[1595]; someMelolonthæin slate; aPolistesin schistus;CarabiandNecrobiain vegetable debris: but some of these rather belong to a comparatively modern formation[1596].
I observed in the outset of our correspondence, that we were entering an august temple, exhibiting in its inmost sanctuary the symbols of the Divine Presence[1597]. In proportion as we have penetrated, glory from that Shechinah has more and more shone forth: and whether we have considered the uses of insects, their ways and instincts, their forms and structure, and their arrangementin a wondrous and complex system, theWisdom,PowerandGoodnessof their and ourCreatorhave every where been marvellously conspicuous, and calculated to awaken in us every devotional feeling. If, indeed, we admire and study these little creatures, or any other department of nature, without reference to theirCreator, and collect and love them merely forthemselves, we shall be in some sense idolaters, and, like the ancient world, put theworksofGodin his place. But if, while we admire them and store them up and study them, we see in them his glory reflected, and in thecreaturelove theCreator, the study of them, in conjunction with that of the written Word, will be highly beneficial to us, and at the same time that it ministers to our temporal enjoyment will promote our eternal interests.
Taking this view, I cannot better close our correspondence on the subject that has so long occupied us, than in the pious words of one of our most admired poets:
"Happy if full of days—but happier far,If, ere we yet discern life's evening star,Sick of the service of a world that feedsIts patient drudges with dry chaff and weeds,We can escape from custom's idiot sway,To serve the Sovereign we were born t' obey.Then sweet to muse upon his skill display'd(Infinite skill) in all that he has made!To trace, in Nature's most minute design,The signature and stamp of pow'r divine,Contrivance intricate, express'd with ease,Where unassisted sight no beauty sees,The shapely limb and lubricated joint,Within the small dimensions of a point,Muscle and nerve miraculously spun,His mighty work, who speaks and it is done,Th' Invisible in things scarce seen reveal'd,To whom an atom is an ample field:To wonder at a thousand insect forms,These hatch'd, and those resuscitated worms,New life ordain'd and brighter scenes to share,Once prone on earth, now buoyant upon air,Whose shape would make them, had they bulk and size,More hideous foes than fancy can devise;With helmet-heads and dragon-scales adorn'd,The mighty myriads, now securely scorn'd,Would mock the majesty of man's high birth,Despise his bulwarks, and unpeople earth:Then with a glance of fancy to survey,Far as the faculty can stretch away,Ten thousand rivers pour'd at his commandFrom urns that never fail through every land;These like a deluge with impetuous force,Those winding modestly a silent course;The cloud-surmounting alps, the fruitful vales;Seas on which every nation spreads her sails;The sun, a world whence other worlds drink light;The crescent moon, the diadem of night;Stars countless, each in his appointed place,Fast anchor'd in the deep abyss of space:—At such a sight to catch the poet's flame,And with a rapture like his own exclaim,These are thy glorious works, thou source of good!How dimly seen, how faintly understood!Thine, and upheld by thy paternal care,This universal frame, thus wondrous fair;Thy power divine, and bounty beyond thought,Adored and praised in all that thou hast wrought.Absorb'd in that immensity I see,I shrink abas'd, and yet aspire to thee;Instruct me, guide me to that heavenly day,Thy words, more clearly than thy works, display,That, while thy truths my grosser thoughts refine,I may resemble thee, and call thee mine.[1598]"
"Happy if full of days—but happier far,If, ere we yet discern life's evening star,Sick of the service of a world that feedsIts patient drudges with dry chaff and weeds,We can escape from custom's idiot sway,To serve the Sovereign we were born t' obey.Then sweet to muse upon his skill display'd(Infinite skill) in all that he has made!To trace, in Nature's most minute design,The signature and stamp of pow'r divine,Contrivance intricate, express'd with ease,Where unassisted sight no beauty sees,The shapely limb and lubricated joint,Within the small dimensions of a point,Muscle and nerve miraculously spun,His mighty work, who speaks and it is done,Th' Invisible in things scarce seen reveal'd,To whom an atom is an ample field:To wonder at a thousand insect forms,These hatch'd, and those resuscitated worms,New life ordain'd and brighter scenes to share,Once prone on earth, now buoyant upon air,Whose shape would make them, had they bulk and size,More hideous foes than fancy can devise;With helmet-heads and dragon-scales adorn'd,The mighty myriads, now securely scorn'd,Would mock the majesty of man's high birth,Despise his bulwarks, and unpeople earth:Then with a glance of fancy to survey,Far as the faculty can stretch away,Ten thousand rivers pour'd at his commandFrom urns that never fail through every land;These like a deluge with impetuous force,Those winding modestly a silent course;The cloud-surmounting alps, the fruitful vales;Seas on which every nation spreads her sails;The sun, a world whence other worlds drink light;The crescent moon, the diadem of night;Stars countless, each in his appointed place,Fast anchor'd in the deep abyss of space:—At such a sight to catch the poet's flame,And with a rapture like his own exclaim,These are thy glorious works, thou source of good!How dimly seen, how faintly understood!Thine, and upheld by thy paternal care,This universal frame, thus wondrous fair;Thy power divine, and bounty beyond thought,Adored and praised in all that thou hast wrought.Absorb'd in that immensity I see,I shrink abas'd, and yet aspire to thee;Instruct me, guide me to that heavenly day,Thy words, more clearly than thy works, display,That, while thy truths my grosser thoughts refine,I may resemble thee, and call thee mine.[1598]"
Inter tot et tantaOptimi Creatorismiracula, quæRegnum Animaletantopere illustrant, vix ulla sunt majori admiratione digna, et Physiologi eruditi introspectione, quam quæ ad generationem insectorum spectant. Quamvis enim inter sexûs organa vertebratorum animalium et insectorum analogia haud parva locum habet; numero tamen, figura et proportione partium, miro modo sæpius differunt; et organa insuper plura in insectis reperiuntur quorum in vertebratis exempla frustra quæsiveris.
Hoc argumentum tractando duo sunt imprimis consideranda,genitalianempe ipsa utriusque sexûs, etcoitus.
I. Degenitalibusin genere prima observatio erit, "quo minor horum, habita corporis ratione, moles, eo magis nervorum systema, et cephalicum imprimis ganglium, predominans fit; eo major igitur intellectûs facultas (instincto naturali consociata) reperitur," ut in principibus,Apibusnempe,Formica, &c.[1599]InHymenopteris, iterum,Dipteris, etNeuropteris, hæc organa maxime retracta sunt; dum inLepidopteris,Coleopteris, etOrthopteris(quorum insuper mascula et feminea insigniterinter se congruunt[1600]), magis exserta jacent[1601]. Genitalia plerumque in extremitate postica abdominis subanosita sunt[1602], sed inArachnidisetLibellulinismasculis in basiventris, inPhalangiosubore, et inChilognathisin anteriore corporis parte subtus latitant[1603]. Ubi organa duplicantur, uttestes, semper symmetrica sunt. Non obliviscendum est quòd in diversis generibus habitu externo persimili consociatis, imò in diversis unius generis speciebus genitalia diversa interdum reperiuntur[1604]: sic in Lamellicornibusstercorariis(Scarabæus,Copris, &c.), testes tantummodo suntduo; inarboreis(Melolontha, &c.)duodecim, et infloralibus(Cetonia, &c.)viginti-quatuor.
Genitalia sunt velmasculavelfeminea.
i. Genitaliamascula, suntpenis;canalis excretorius;vesiculæ seminales;vasa deferentia;testes;prehensores; etsemen.
1.Penis[1605]quoadsubstantiamplerumque membranaceus, at interdum corneus est, et intus cavernosus[1606]; inColeopterisapice vagina bivalvi vulvam aperiente instructus est[1607]:figuravariat admodum, sæpius tamen cylindricus vel subcylindricus est; inBlattisapicem versus sensim attenuatus[1608]; inCherme Pyricapitatus[1609]; inVespa vulgaricochleariformis[1610]; inCrabronebilobus[1611]; inPoliste gallica? incurvus et apice bicornis[1612]; inSarcophaga carnariaapice spinosus[1613]; inMegachile murariadifformis[1614]; inTyrophaga Caseiet quibusdam aliisMuscidis, spiralis[1615]; inCordulia æneaetPhalangiobiarticulatus[1616]. Utplurimum nudus est, sed inTephritefimbriatus. In insectis proprie dictissimplexest hoc organon, inScorpionibusautemduplexevadit; quod fit etiam in quibusdam reptilibus,Serpentibusnempe etLacertis[1617].
2.Canalis excretoriuse concursu vesicularum seminalium formatur, et apeneexcipitur in quo terminat et cui semen reddit; interdum brevissimus est, ut inBlatta[1618], et interdum iterum prælongus, ut inBlapte Mortisaga,Tyrophaga Casei, et aliis[1619]. Plerumque cylindricus est, musculosus, compactus, et externe tracheis pertextus[1620].
3.Vesiculæ seminalesconniventes formant, ut jam dictum est, canalem excretorium communem cujus prolongatio bifida esse videntur; vasa deferentia hinc excipiunt. Interdum vasa hæc ac vesiculæ seminales eodem loco in canali excretorio communi terminant, unde canalis hic tumidior fit[1621]. Vesiculæ supradictæ maxime variant: modo canalem exhibent ventricosum, tortum, implexum, longissimum; modo rectum, breviorem. In plerisqueduæsunt vesiculæ seminales, etiam inLepidopterismonorchidis; in quibusdam (Tenebrione Molitore,Hydrophilo piceo)quatuor[1622]; in aliis (Dytisco marginali)sex[1623]; et, inLocustisetBlatta,plurimæ[1624]. Breves admodum sunt inOrthopteriset quibusdamColeopteris[1625]; sed in aliis longissimæ; inOrycte nasicornivicies, et inCetonia auratater decies corpus longitudine superant[1626]. In hisce organis semen e testibus per vasa deferentia acceptum ante emissionem elaboratur.
4.Vasa deferentiaita appellantur quia semen e testibus acceptum ad vesiculas seminalesdeferunt. Ex utroque teste unum vas deferens exit, et si utrinque plures sint testes, ut inMelolontha[1627],Cetonia, &c., omnia ad unicum utrinque canalem formandum confluunt, qui vesiculis supradictis semen reddit: interdum, ut inLepidopteris[1628], ab his nullo modo separantur, unum canalem aut tubum formantia; sed in aliis penitus sunt distincta[1629]. Ex eodem filo quo contexuntur testes vasa deferentia sæpius deducuntur.
5.Testesorgana sunt semen primum secernentia: variantcompositione,numero, etfigura. In quibusdam (LepidopterisetHymenopteris) sunt compacti vasculis visui se subducentibus; in aliis (Orthopteris,Neuropteris,Dipteris, et quibusdamColeopteris) e vasculis brevibus cæcis variique voluminis conformati sunt, atque tunica densa tenaci vel rete tantum mucoso obducti[1630]; vel iterum ex unico variisque modis tecto canali varie contorto et implexo, qui deduci potest et haud raro massam ovalem trachearum ope contextam refert, conflantur, ut inColeopteris Prædaceistam aquaticis quam terrestribus[1631].
Numeroetiam variant testes. QuædamLepidoptera, utPontia Brassicæ, itemIulidæ[1632],unicogaudent; pleraque tamen insecta animalia vertebrata hic æmulantur, et testibus instruunturduobus; inNepa cinereaet reliquisHemipterisquatuor vel quinque[1633], inMelolontha vulgarisex[1634], et inCetonia aurataduodecim[1635], utrinque deteguntur. Interdum ex acinispluribus compacti videntur, et bacciformes appellari possunt. InLamiaduodecim glandulæ in utroque teste coalitæ inveniuntur[1636], et inTenebrione Molitoreplurimæ[1637].
Quoadfiguram, interdum, ut inPontiaPapilionum genere, spherici evadunt[1638]; inGryllopyriformes[1639]; inApe mellificaoblongi[1640]; lineares et longissimi inProcruste coriaceo, in quodecieslongitudine corpus superant[1641]; inNepa cinereasub-ovati, et singuli filamento longo varie convoluto et contorto terminati[1642].
Inlarvisetiam hæc organa detegere est. Sic in erucaPontiæquatuor testes sunt utrinque, vel potius unicus ex quatuor serie ordinatis, conflatus[1643]. Hi sensim coacervantur donec in sphæricum testem antea descriptum coalescant.
6.Prehensores[1644]sunt organa figura varia quibuscum mas in coitu feminæ anum corripit et comprimit. Quoddam analogum in quibusdamMammaliis,Avibus,Piscibus, etReptilibus[1645]invenitur, sed in insectis maxime conspicui. Eorumsitus,numerus; etforma, sunt notandi.
Quoadsitum—circa foramen per quem prodit penis sub ano plerumque sunt inserti, sed inConopecornu prehensorium in segmento ventrali antepenultimo deprehenditur[1646]; et inLibellulinis, præter prehensoresanales, par est aliud anum spectans, in secundoventrissegmento pone penis ipsius situm[1647]. Prehensorumnumerusminime constans: plerumqueduosunt, sed inCicada,unicusfurcatus tantummodo videre est[1648]; inLepidopterisvariis,Conope,Libellulidis,tresanum armant, difformes tamen[1649];duo paria Culicemsignant[1650],Megachilem murariam[1651],etAgrionidas[1652]; inLocustisveris intra abdomen retracta sunt hæc organa; in pupa tamenL. morbillosæ, in nostro musæo asservata,quinqueapparent;sexinFormicisDe Geerius detexit, sed in cognato genereMyrmica,duotantum[1653];quatuor paribuspostremoTipula oleraceainstructa est. Prehensorumformamultifarie variat, imò haud raro in specie eadem: interdum enimprehensionisoli hujusmodi instrumenta sunt adaptata, aliis diversæ figuræcompressionemefficientibus; interdum et utroque munere funguntur. InPontia Brassicæ, in qua parunicum, concavo-convexi sunt, deltoidei, intus setis rigidis fimbriati, et apice dente incurvo armati[1654]; inAcrida variatenues, simplices, recurvi; inSpilosomate lubricipeda, quætribusgaudet, laterales sunt concavo-convexi, ovati, dum intermedius brevior est, triangularis et unguiculo armatus[1655]; inCordulia ænea, et affinibus,duo superioressunt lineares et undulati, etinferior unicusprofunde bifidus[1656]; inVanessa Urticæexteriores duo sunt conchiformes, par autem interius unguiforme[1657]; inCulicesuperiores longiores conici hirsuti, inferiores breviores et ut in præcedente unguem referunt[1658]; inTipula oleracea, in quaoctupliciprehensore anus armatus, valvulæ omnes figura diversæ—par exterius nempe concavum membranaceum reliquos includens, secundum unguiculatum, tertium subclavatum, et ultimum fere lunatum[1659]; inMegachile muraria, inter alios diversos, unum par literæ T formam habet[1660]; inBomboforceps analis bivalvis est intus ramosus[1661]; et inPanorpacheliformis[1662].
7. Desemineipso insectorum paucula sunt notanda. Fluidumest spissum, lacteum, granulis repletum; sub lente punctula numerosa, nigra, oblonga, incurva, in illo deteguntur. Quoadanalysinejus, neque alkalinum neque acidum est, sed quoddam neutrum inter hos intermedium. Ex sanie vel sanguine deoxydato, et durante coitu copiosissime secernitur: in aqua tepida solvitur, et conquassatum fundum petit: spiritu vini rectificato superfuso flocculi quidam formantur[1663].
ii.Genitaliafemineavulvaexcepta antea tractavi[1664], hæc est tubus subcylindricus, foramine ovali vel lunato ab ano distincto, cum matrice connexus, et per quem semen in coitu transmittitur. InScorpionibusduplicem esse vulvam affirmatur duobus ovariis connexum[1665].
II.Coitus.—Coitum insectorum tractaturo paucula de lenociniis amatoriis, et aliis ejusmodi, quæ antecedunt, sunt prædicenda.OlfactumaresPhalænaruminterdum feminam latentem, uti canis leporem, odorantur[1666]; splendore phosphoricoLampyrideset quorundam aliorum insectorum feminæ maritum ad lectum gramineum prælucent; et huc referri forsan debet plurium cæcus ardor lumina circumvolandi, vel etiam in lumen irruendi;sonusexcitat feminasCicadarumetGryllinarum[1667], &c. ad amores, et cantu stridulo querelisque amatoriis diem ducit mas cupidus, donec sponsa advolat, et tori foliosi fit haud invita particeps. Sonitu etiam uterque sexus formidatiAnobiimutuo sese provocant ad venerem[1668].
In plurimis tamen insectis femina fit modestiæ et pudicitiæ exemplar, et non nisi difficillime et capite averso maris ardori se tradit. In insectorum moribus et œconomia virtutum plurimarum typum quendam et delineationem nobis proposuitDeusO. M., quem imitari nos voluit, interdum jussit[1669]. Sicexcitare nos ad laborem indefessum, ad prudentiam item et amorem erga prolemFormicædedit[1670]:Apiad devotam sui consecrationem, et omnium facultatum et virium ad reipublicæ emolumentum, ad obsequium quoque verum erga parentes et regem[1671]; atque ita, ut jam dictum est, in re amatoria insectorum feminæ sæpe speciem præ se ferunt pudoris et castitatis, et virginibus verecundiam, virtutum omnium custodem, et sexûs sui ornamentum maxime proprium, moribus suis prædicant. Hujus modestiæ exemplar insigne præbentLibellulinæ. Œstro amoris concitus, mas feminæ collumprehensoreanali triphyllo arripit et avolat, illam quasi prædam secum gerens; sponsæ sic electæ, persuadere in animo est ut caudam suam inflecteret, et ad coitum se daret, quod, illa invita, fieri nequit; maris enim genitalia, ut antea dictum est, in basi ventris sita, feminæ vero in extremo ano; hinc, nolente illa, vix fit coitus, et sæpissime longo et vano labore, huc illuc volando virginem protervam frustra solicitat; sed tandem lacessitus aquas petit, quas sponsæ cauda longa, me teste, sæpius flagellat, donec defatigata, et quasi ex frigido calorem concipiens, demum et sensim caudam inflectit, et se reddit amori[1672].Araneamferocem, sævam etiam in amoribus, mas caute appropinquat, et, si blanditiis ejus minus propitiam sese ostendat, cito resilit, ne osculorum loco morte donetur: coitu etiam peracto, pede veloci ab uxore se subducit, quæ illum, imo post Veneres, aliàs forsan voraret[1673]. In genere mares feminas antennarum et abdominis motibus et frictione lenocinantur et ad coitum provocant.
Insecta sunt alia, utPhalænæ,Muscidæquædam, etApis mellifica, in quibus inversa est hæc naturæ lex casta; harum enim feminæ marem petunt, vel blanditiis alliciunt ad amores.
Nunc decoituipso tractabimus, in quo hæc sunt præcipue notanda—modus,statio relativa,locus, etduratio.
i. Plerisque insectis penisintransest, sed inMuscidisquibusdam inversa est lex, et feminæ tubus retractilis analis, foramen sub ano maris penetrat et ita coëunt[1674].Araneidissingulari et mirabili prorsus modo fit coitus; organi enim masculi functio partim palpis et partim membro ventrali delegatur: prioribus includitur glans quæ pudendum femineum penetrat, et sic in utroque sexu, palpis ambobus alternis vicibus huic officio inservientibus, orgasmus venereus producitur, cui insequitur fœcundatio, ab organoventralimasculo; femina tubercula duo supra genitalia sita in rimas totidem inter branchias maris immittente, et in temporis momento omnia peracta sunt[1675]. Listerus, De Geerius, et alii in zootomia periti, in palpis latere organum masculum crediderunt, sed ex observationibus et dissectionibus Trevirani patet, testes et vesiculas seminales in abdomine locum habere[1676]; sed exitus horum solummodo in orificio[1677]; in palpis e contra est organum exsertile penem referens, quod in coitu erigitur et fere glandiforme est: hinc deduci potest, ut videtur, quod utrumque organum pro genitale habendum, et fœcundationem feminæ ab utroque pendere.
ii.Statio relativa.In plerisque insectis, durante coitu,marisstatiosuperiorest, etfeminæinferior, in hujus dorsum conscendente illo; interdum tamen hæc lex inversa est, et marem femina ascendit, quod ipse vidi inVespa vulgari, etScatophaga; inPuliceetiam femina superior, sed more humano os ori[1678]; quod fit etiam in aliis quibusdam masculo prædominanti, nempe inCryptophagoquodam minuto, nostris sub oculis, inZygæna,Culice, etPhalangio[1679]. In insectisOrthopteriset pluribusHemipterissexus in coitu sibi invicem a latere paralleli stant[1680]; sed in aliisHemipteris, saltem inPentatomate,more canum capitibus aversis, quod fit etiam in quibusdamTipulidis, res venereas peragunt[1681].
iii.Locus.Interdum interramet intergramina; interdum interarborumetfruticumramos, et sub foliis; interdum iterum superaquas; et in ipsoaëredemum haud raro amoris gaudiis ultimis fruuntur; hîcEphemeræcaducæ in ipso venere choreas ducunt; sursum et deorsum, memetipso teste, alternatim volitantes[1682]: hîc etiamApumregina et mater in sublime fertur maritum infelicem petens, qui voluptatem brevem vita emat[1683]:Phalænarumfeminæ apteræ hue illuc per aërem inter arbores trahuntur a mare alato[1684]; et quarundamTipularummares a feminis tracti, per aërem item durante coitu rapiuntur. Modeste satis coëunt insecta, utplurimum plantarum sub umbra latitantes; et plura insuper, ut quædamTipulæ,Tineidæ, etBombycidæ, sub cortina alarum abdomen omnino tegente, veneri se tradunt[1685].
iv.Duratio.Coitus horum animalium duratio varia, interdum, ut inAraneidis, spatio perbrevi conficitur, in quibusdam tamen plus uno die opus est. Plures feminas interdum aggreditur idem mas, hoc inBombyce,Chrysomela Polygoni, etMusca domesticaobtinet.Aphidemmasculum cumquinquefeminis successive copulantem De Geerius videbat[1686].
N.B.Interpupas Orthopterorum et Hemipterorumcoitus interdum locum habet, quod maturiorem organizationem in hisanalogis,quam in aliis insectis probat.