AN INQUIRY INTO THE Original Production OF INSECTS IN Human Bodies.

NOT only have the manner of Secretion and Uſe of the Ge⯑nital Liquor been the occa⯑ſion of Diſputation, but alſo its Matter and Compoſition have been the Subject of much Inquiry; and the Methods they have uſed for Satisfaction, were, (1ſt) Hypothetic Arguments. (2ly) [4]Experimental Examination. Of the firſt ſort, viz. Inquirers, or rather Gueſſers, are, (1.) Such as derive the Sperm from the Brain only. (2.) From Brain, Heart, and Liver. (3.) From an uncertain Juice convey'd from the Brain along the ſpinal Marrow to the Spermaticks. (4.) Such as aſcribe a ſpermatick Force to the Kid⯑neys. (5.) Such as will have it to be a Mixture and Temperature, taken from all the Facultys of the Soul. (6.) Such as plead that it falls from the parts of the Body into the leſſer Veins, and out of them aſcends into the greater, and ſwims like a Cloud upon the Humours; and is at laſt attracted by the force of the Teſticles. (7.) Some derive it from all the Parts of the Body; others from the Maſs of Blood only. (8.) Some wholly reject the laſt, and fetch it from a ſweeter Juice, or ſome milky chylous Matter. (9.) Others ſay it's the Excrement or Reſiduum of the moſt elaborated and finely digeſted Juices, falling like a Dew from all the Parts of the Body, and meet⯑ing at the Spermaticks. (10.) Some will have it to be only a ſimple uncom⯑pounded nervous Juice, deſtitute of all other Mixtures.

Theſe were the chief Opinions of the Hypothetical Gentlemen, and each of them had their Patrons and ſtrenuous De⯑fenders; [5]who rack'd their Wits to in⯑vent Arguments to maintain their darling Notion: And many of their Arguments are fitter to move Laughter, or raiſe the Choler of the ſober, than to ſatisfy his Curioſity, or inform his Judgment. Where⯑fore ſome who were diſſatisfy'd with this ſuppoſititious or gueſſive Way of arguing, I go with them next to experimental Ex⯑amination; the firſt whereof hath cauſed the animal Seed to undergo the fiery Trial of the Chymiſts Furnace, to make it diſcover its Principles, but found it conſiſt only of the ſame with all the Parts of animal Bodies; viz. An inſipid Wa⯑ter, a fetid Oil, ſome volatile Salt, a Re⯑ſiduum of much light Earth in the Retort; but in Rectification it afforded no Spirit. See Act. Erudit. Lipſ. Supplem. tom. 4. Sect. 10. p. 445. And Borellus. Obſ. Med. Phyſ. cent. 3. Obſ. 5. p. 237. Et chymicos qui ſperma & ſanguinem humanum coctione in pediculos muſtaſque converterunt, ſe fidiſſe refert. And, Gabr. Glauber. de Tinct. Ʋniverſal. cap. 5. p. 134. ſays, Eo dementiae pervene⯑runt nonnulli Chymiſtae, ut pro conficiendo ſuo lapide Philoſophico, materiam in ſper⯑mate humano quaerunt. But ſtill ſome Mens curioſity, not being ſatisfy'd with all theſe Gueſſes and Experiments, they next try what they can diſcover in it, [6]by ocular Examination and Demonſtra⯑tion; whereby they are convinc'd, that the Sperm is only a Croud of Animalcula, or ſmall Worms, with long Tails, like Tadpoles, ſwimming in a viſcid Serum. And they are ſo found of this notable Diſcovery, that Leewenhoeck and Hart⯑ſecker are like to go by the ears about it, each challenging this for his own Ob⯑ſervation and Invention: But let them differ as they pleaſe, we know it belongs to neither of them, for D. Ham firſt of all obſerv'd theſe Animalcula in the Se⯑men of a Cock. And long before any of them, Ludovicus Bonaciolus adviſes us, when we are ſolicitous to know whether a Woman be conceiv'd with Child, to take her Urine, and put it into a Glaſs Veſſel, ſhut it up, and ſet it three days in the Shade; then filter it thro' a Linen Cloth, and if you find therein little Worms like Lice, then he ſays ſhe is certainly conceiv'd. Now one wou'd think that theſe were Leewenhoeck's Ani⯑malcula, or little perfect Men, come down from the Ʋterus to keep centry in the Neck of the Bladder, till they be waſh'd off by the Urine, and chang'd into ſmall Lice. A ſtrange Metamorphoſis indeed, Men become Lice! But to aſcend higher; Plutarch, in his Sympoſiacon, Lib. 8. Queſt. 9. diſcover'd and deſcrib'd a Sper⯑matick Worm, ſaying, Hoſpitem noſtrum [7]novimus Athenis Ephebum cum multo ſe⯑mine ejeciſſe Beſtiolam aſperam multis pedibus celeriter ambulantem. But nei⯑ther is this Doctrine of Seminal Animal⯑cula without its Opponents; for Iddo Wolfius, Philip Verheyen, Chriſtianus Vater, Johannes Langius, Andreas Otto⯑mar, Gaelickius, and ſeveral others, flatly deny the Exiſtence of any ſuch Infects in the Genital Liquor, and ſay, that what is ſuppoſed to be theſe Animalcula, is only Flatus's of Air, intermix'd with the Sperm, which, ſeeking to unbend them⯑ſelves, or make their eſcape, cauſe that Motion in the Seed.

But we ſhall allow the Maſculine Semen (like moſt other Fluids) to abound with theſe little Infects, and ſhall attempt to give a rational Account how they come into it, and are bred in it, and why they are more conſpicuous here than in moſt other Fluids of the Body.

It's the Opinion of ſome, that whilſt we are young, and our Stomachs weak, the Ova of Inſects taken in with our Food and Air may eſcape the Attenuation, Digeſtion, Communication and Attrition of the Stomach and Inteſtines, and lie there and generate Worms, which may [8]again depoſite their Ova in the Guts, ſome whereof may be ſo ſmall as to en⯑ter the Lacteal Veſſels, together with the Chyle, and mix and circulate with the Blood, and be ſtrain'd off by the ſperma⯑tick Veſſels, ſooner than any other Sub⯑ſtance, becauſe of their ſmoothneſs and politeneſs; and if they be ſo ſmall as to enter the ſmall Pipes, they may be readily convey'd along all the Gyres, Turnings and Windings of the Teſtes and Epididymides, till they arrive at the different Veſſels, and thence get into the ſeveral Bladders, whither there are daily arriving other new ones, till the Age of Puberty, or time of Seminal Diſcharge: And that thus the Seminal Bladders, from a ſup⯑pos'd continual Addition of new Ova, may be ſtretch'd forth and extended, juſt as the Inteſtines of the Foetus, are full of Meconium before the Birth, and the Bladder full of Urine. Now when theſe Ova are got into the Veſiculae Semi⯑nales, where they are at reſt, and lie till the Boy is of Age, and there generate, and become little Inſects, and ſo cover the Surface of the Seed-Bladders, they ſhall never be free of that Spawn, till we are capable of Generation; but when we are grown to Strength, our Stomachs and Inteſtines are ſo ſtrong, that they attenuate, digeſt, and grind down, not [9]only the Inſects which we ſwallow, but the Ova alſo.

To all which may be anſwer'd, That it's improbable and impoſſible that theſe impregnated Ova ſhould lie in the Se⯑minal Bladders, from Infancy to Puberty, without coming to Life: And if they ſhould become live Infects, and breed without any Evacuation of them for ſo many Years, what irreparable Miſchief muſt they firſt make upon their containing Seminal Bladders, and then upon the cir⯑cumjacent Parts, Inteſtines, Bladders, Pe⯑ritoneum? &c. And none can deny this, who have read Sennertus, Schenckius, Spigelius, and others, who have ſeen and written on the Tragedys acted by Worms, how they have corroded the Stomachs and Inteſtines of Children, and even eaten their way thro' the Belly and Navel; yea, that they conſumed all that fleſhy Part on the Groins, and came to the Surface of the Body. Now if Vermin make ſuch Diſpatch, in a ſhort time, upon thick and ſtrong Inteſtines and Muſ⯑cles; I do not ſee how the delicate Se⯑minal Bladders can, for 15 or 16 Years, impriſon ſuch innumerable Numbers of Animalcula, generated and bred from ſuch a heap of Ova, as from Infancy to Puberty are daily added to them from the Teſtes and different Veſſels; beſides [10]the prodigious Myriads which are ſtill generated from the diurnal Generation of the formerly repoſited Ova and Inſects: for what may be done by a few Worms or Maggots in a ſhort time, may certain⯑ly be expected from a vaſt Congeries of little Animals, in ſo many Years; eſpe⯑cially ſeeing there is both a daily Gene⯑ration there, and a continual new Addi⯑tion from the Teſtes. How quickly is Cheeſe conſumed by Mites, Leaves of Trees by imperceptible Inſects, Hair of Animals by the Tinea or ſmall Mite, and ſolid Wood it ſelf into Duſt by minute Inſects?

But ſuppoſe it ſhou'd be anſwer'd, that the Ova arriving at the Seminal Bladders, are ſo very ſmall, and the number ſo in⯑conſiderable, that we need be under no Apprehenſion of Danger from them: yet this affords no Satisfaction when we con⯑ſider,

Firſt, That from Infancy there's ſup⯑pos'd to be a continual Addition of new Ova, ſtretching forth and extending the Cavitys of the Seminal Bladders, till the Boy be of Age.

Secondly, When we reflect on the ſud⯑den Generation of Inſects every where, (for a Chryſalis in which a Worm had been wrapt up, will be full to day, and to morrow quite empty, and the Butter⯑fly [11]got out of it, flying abroad in its full Stature and Magnitude) ſince this Generation is ſo ſudden, and their Spawn ſo numerous; this deſtroys their Argu⯑ment, who ſay that theſe Ova may be laid up in the different Veſſels and Se⯑minal Bladders, till the Boy comes to the Age of Puberty. The Difficultys ſuch Gentlemen leave us in the dark a⯑bout, are as great as any they can re⯑move: for,

Firſt, Let us ſuppoſe that theſe Ova may lie in a Quies in the Seminal Blad⯑ders, till the Age of Puberty; then what prevents the Generation of theſe repoſited Ova, and impregnation of the Animal⯑cula in the Veſiculae Seminales, until the Boy be Puber? Or what is there to im⯑pregnate, and render them fruitleſs after that time, which there was not before? What hinders the Corruption and Putre⯑faction of theſe ſmall Ova, lying ſo many Years in a warm moiſt Place, which is fit either for Generation or Corruption? But,

Secondly, If they did generate, (as it's moſt probable they would, if they were there) how could theſe ſtrait Bladders be capable to contain ſuch a vaſt Croud, as a diurnal Generation in that place, and a daily new Supply from the Teſticles, muſt amount to. 'Tis ſurprizing that any [12]ſhould pretend that theſe Ova ſhould be ſtrain'd off only by the ductus ſperma⯑tici, when we are aſſur'd from Expe⯑rience, that they are ſtrain'd off and ge⯑nerated in all Parts of the Body, both internally and externally. And according to theſe Gentlemen's Hypotheſis, when the Ova are got into the Seed-Bladders, ſeeing they are for ſeveral Years ſhut up in theſe Cells, we might expect them to produce Maggots, were they capable of ſuch Growth and Bulk. And as a Conſequence of this, the firſt ejected Semen would be chiefly a Heap of Worms or Inſects, inſtead of ſmall (and impercep⯑tible by the naked Eye) Animalcula: And according to this Opinion, more Sperm ſhould be ejected the firſt Year after Puberty, than in ſeveral Years after, and that Sperm ſhould be better elabo⯑rated and fuller of Animalcula; and, ſup⯑poſing theſe Animalcula ſo many Em⯑brios of human Foetus's, ſhould be more productive of ſtrong, healthy and lively Children: all which is contradicted by daily Experience.

Laſtly, Seeing theſe Infects are ſo ſhort liv'd, then if they generated in the Veſi⯑culae Seminales ſo many Years, the great⯑eſt number muſt be dead, putrify'd and rotten in that time. And one would think it very improbable for the reſt to live in [13]ſuch a Kennel of Filthineſs, eſpecially to feed upon the putrify'd Carrion of their own Species, which certainly muſt make up a conſiderable part of their repaſt.

Secondly, I ſhall give the Reaſons which ſeem to me more probable, why Children have not Animalcula repoſited from Ova in their Seminal Bladders (ſup⯑poſing theſe Ova to come from without and ſwallow'd down, together with our Air and Food) altho we had an Oppor⯑tunity to examine with a Microſcope, that thin, uſeleſs, inſipid Mucilage, contain'd in the Teſticles, Epididymides, different Veſſels, and Seminal Bladders; becauſe,

Firſt, During Infancy the ſtraining Veſ⯑ſels or Glands of the Teſticles are too narrow and ſmall for the Ova to paſs; which is further prov'd from ſuch Obſer⯑vations as ſhew that the Ova being mix'd with the Blood, when that comes to paſs the capillary Veſſels, the Diameter of the Egg being larger than the Cavity of the Veſſel, it muſt ſtop there, and be wedg'd in by the Force of the Fluids behind; is hatch'd by the Body's Heat, and produces a Worm or Worms, if o⯑ther Ova arrive at it, and ſtop alſo: And this Caſe we know has often happen'd in moſt parts of the Body. Thus Worms have been bred and found in the Liver, Kidneys, Bladder, Blood-Veſſels, Brain, [14]Eyes, Teeth, Ears, Noſtrils, Feet, Na⯑vel, Heart, Lungs, Spleen, &c. Some⯑times where Ulcers or Abceſſes have ſeated themſelves in any external Parts of the Body, there have been found Worms in them: Of theſe Herod, Sylla, and Aleman, were eaten up, and are called by Coelius Aurelianus, pediculi ferales. I ſhall not here treat of the ſundry Kinds of Infects found in the Inteſtines; Andre and Le Clerc have written well on this Subject; but eſpecially the learned Va⯑liſnerius, who hath carefully diſſected ſeveral of them, and hath oblig'd the World with a curious Anatomy of them. And tho Worms have bred in moſt other Parts of the Body, yet we have ſcarce any Inſtances, where they have been obſerv'd to generate in, or be diſcharg'd from the Subſtance of Childrens Teſtes. Wherefore I am ready to think that theſe ſecretory Ducts, which ſtrain off the Semen from the Blood, are very narrow, and there⯑fore the Eggs cannot enter nor paſs them, but are, together with the Blood, returned back to the ſpermatick Veins. This O⯑pinion appears more ſatisfactory, becauſe the Sperm ſeems to conſiſt of more ela⯑borated Particles, than the matter of o⯑ther Evacuations; for its more ponderous Subſidy in Water is of a thicker Con⯑ſiſtence, and condenſes ſtill more in Spirit [15]of Wine; but if it be laid on a dry Place, expoſed to the Air, it preſently becomes fluid, tranſparent, and loſes its Viſcidity. The Production of Worms in the miliary Glands, on the Surface of the Body, is no good Argument againſt this: for,

Firſt, When the Ova get out of their road, into the Labyrinths of the miliary Glands, they cauſe an Obſtruction and Tumour; they breed there, break the ſmall Veſſels, and get thro' the Skin.

Secondly, Worms are ſometimes pro⯑duc'd on the Surface of the Body, (where the Skin is excoriated) from the Ova floating in the Air, falling upon the grieved Place, and taking up their Abode there, and generating others.

Thirdly, It's not improbable that the Ova of theſe Animalcula of the Maſcu⯑line Semen, are greater than the Ova of ſome larger Inſects; and then it's no wonder that they neither paſs the mi⯑liary Glands, nor the ſpermatick Laby⯑rinths of Children.

That ſome particular Glands have ſuch narrow ſecretory Ducts, as will not al⯑low the Ova to paſs readily, is ma⯑nifeſt,

Firſt, From the ropy Matter diſcharg'd from the Penis, upon intenſe amorous Thoughts, or laſcivious Converſation, [16]which tho more tenacious then the Se⯑men, and ſtrain'd off by the Glands of the Ʋrethra, yet we do not hear of any Animalcula taken notice of in it.

Secondly, Leewenhoeck owns, that Mens Semen has no Animalcula, and this he aſſigns for a reaſon of Sterility; but hereof he gives us but one Inſtance, and for any thing we know, the fault even of this might be from ſome indiſ⯑poſition in the Ova foeminaea, Tubae fallo⯑pianae, Ʋterus, or ſome of the circum⯑jacent Parts; or the Male Sperm might want that Vivacity, Subtility, or forcible Projection: but however theſe were, yet we may ſafely impute his want of Animalcula to the narrowneſs of the Me⯑anders of the Teſtes.

Thirdly, The Flaccidity and Emptineſs of the different Veſſels and Seminal Blad⯑ders before Puberty, and the minute Portion of Semen, diſcharg'd by Boys for ſome Months after the firſt Seminal Eva⯑cuations; yea ſuch is the Penury of it, that we have Hiſtorys of ſome wicked Boys, who deſiring to anticipate Nature, and gratify their too early libidinous De⯑ſires, have ejected Blood inſtead of Sperm.

Fourthly, Not only the ſmall quantity, but the tenuity and aqueouſneſs of their genital Liquor, ſhows the narrowneſs of their ſpermatick Strainers.

Fifthly, In old Age, when the Tubes contract the Canals are ſtraitned, and few or no Ova paſs; there's but little Semen ſeparated from the Blood, and what is ſtrained off is moſtly uſeleſs, either for Generation or Stimulation to Venery.

Laſtly, The Spittle has likewiſe paſs'd the Microſcopial Examination; but Lee⯑wenhoeck could obſerve no Animalcula in it, and we are ſure that that Secre⯑tion has a much ſhorter way to paſs, after its Separation from the Blood, till it come into the Mouth; ſo that if the narrowneſs of the Glands hinder'd not the Paſſage of the Ova from the Blood, we ſhould rather expect them here, than in the Semen.

Hitherto I have ſpoken of the Viſibility of the Animalcula in all Male Semen: But now let us try how we can account for ſuch vaſt Multitudes of Inſects in this Liquor.

The firſt reaſon then, why I ſuppoſe we meet with greater Numbers in this Liquor than in ſeveral other Secretions of the Body, is the ſlow Circulation of the Blood in the Spermatick Veſſels, whereby the ſeminal Particles have time to approach and attract one another: For the Courſe of the Blood in the ſper⯑matick Arterys, betwixt the great Ar⯑tery and the Teſtes, Dr. Keil has demon⯑ſtrated [18]to be 150 times ſlower than the Motion of the ſame Blood would be in the great Artery, or even in the Iliacks. And if its Motion decreaſe ſo quickly in the firſt Diviſion from the Aorta; how much more languid then muſt its Motion be in the many Diviſions, Subdiviſions, Turnings and Circumvolutions of the te⯑ſticular Glands! No inward Secretion or Circulation is ſo ſlow in the whole Body, it being little more than what ſeems ne⯑ceſſary to prevent the Blood's ſtagnation.

Secondly, The long Retention of the Semen in the different Veſſels and Semi⯑nal Bladders, which is more obſtinate than any one, or all of the Abdominal Secre⯑tions. To this I add,

Thirdly, The ſpeedy and ſurprizing Ge⯑neration of Inſects, the Breeding, quick Growth, numerous Progeny, and ſhort Life, of the Butterfly and Silk-worm, Fleſh-fly, and Fly-Maggots, may be ſeen at large in Leewenhoeck's Obſervations. Now if theſe are bred and come to Ma⯑turity in ſo very few Hours, how much ſooner the Ova of the Animalcula, which are much leſs, and may therefore be ſup⯑pos'd of much ſhorter continuance? I might alſo inſtance, in the ſurprizing, ſpeedy, and prodigious Progeny of the ſmall Worms called Aſtarides, great Num⯑bers whereof I have known bred afreſh [19]every Night, and evacuated next Morn⯑ing at Stool: Let us then ſuppoſe the Generation of the Seminal Animalcula to be as ſpeedy; if the Ova ſhould paſs the Glands, and get into the Seminal Bladders during Childhood, what Veſicu⯑lae Seminales would be capable to con⯑tain the great Fry of ſmall Worms, bred in the ſpace of 15 or 16 Years?

Fourthly, The Sperm is ſeemingly the moſt homogene Secretion of the whole Body, and the moſt agreeable for the Generation of theſe Animalcula, being it ſelf, not only a prolifick, but a ſmooth balſamick Fluid, ſeemingly endu'd with all Propertys which can conduce to ren⯑der a Liquor either fertile or nutritious. If we conſider theſe things, we ſhall ſee Reaſon to be of that ingenious Gentle⯑man's Opinion, mention'd by Dr. Blair, who thinks that theſe Animalcula are the ſame with thoſe we ſee in Water, but under different Shapes.

But let us next enquire for the Cauſes why theſe ſmall Inſects are either not ſo numerous or perceptible in the Blood, Bile, Urine, or pancreatick Juice. And,

Firſt, None of theſe ſeem of ſo agree⯑able a Nature, have neither ſo much reſt, nor afford ſo proper Nutrition.

Secondly, Becauſe, as Dr. Blair ſays, the Blood being a Compoſitum of all the [20]various Particles of the whole Fluids in the Body; it appears, under a more ſo⯑lid form in Globules, where the ſeveral Particles are compactly and firmly united, ſo that the Ova or Animalcula are not ſo perceptible, unleſs the Particles were ſeparated into their different Parts; and even this Heterogene Mixture call'd Blood has ſometimes had Worms in it.

Thirdly, Theſe Animalcula ſeem to meet with the cruelleſt Treatment in the Bile; for altho ſeveral Phyſicians and Na⯑turaliſts have obſerv'd abundance of live Worms in the Liver, yet rarely have they been found alive in the Bile or Gall-Bladder: for this is the moſt pur⯑gent, ſharp and bitter of all the Secre⯑tions, and is chiefly made up of very ſharp Particles like ſmall Wedges; whereby, when by the periſtaltick Motion of the Guts it's mix'd with the Food and Fluids, it breaks their acrid ſaline Particles, as well as divides the coagulated, or mixes the watry and oily: The pungent bilious Particles are darted into either the Bodies or Ova of Inſects, that are larger than the bilious Particles in the Inteſtines, and kills them if alive, or prevents their Generation if they be only in Ova: But the Ova or Animalcula ſwallow'd with our Meat or Drink, being both ſo nu⯑merous and ſmall, get out of the Duode⯑num [21]unhurt; but if the Bile be pure and unmix'd, very few Species of Inſects can live in it.

Another Reaſon why many Ova and Inſects may get out of the Inteſtines un⯑touch'd by the Bile, is, either its ſcarcity in the Body, from the ſecretory Ducts of the Liver being ſtuffed with a gritty Matter, cauſing a Jaundice; or its meet⯑ing with obtundent and tenacious Meat, Drink, or Medicine, often pour'd down into the Stomach. And, laſtly, The A⯑nimalcula are not ſo conſpicuous in the Bile, becauſe it's of a darker Body than the Semen.

Fourthly, The Pancreatick Juice is conſtantly flowing into the Duodenum, as it's ſeparated from the Blood, and ſo the Ova have but a ſhort Reſidence there to generate Inſects. And ſuppoſe they were in it, its immediate Mixture with the Bile, would render it very diſa⯑greeable to live Inſects. This Mixture of the two Juices prevents our Diſco⯑very of Animalcula; or perhaps the Tex⯑ture of the procreatick Glands may not be ſo convenient for their Conveyance.

Fifthly, The Urine being often full of pungent Salts, they would be darted into the delicate Bodies of theſe little Creatures; therefore are we not to ex⯑pect them ſo frequently and plentifully [22]in that Liquor, it not being of ſo ami⯑cable a Nature for ſuch Gueſts: And alſo ſeveral times have there been Worms voided with the Urine; yet do I not find that either Leewenhoeck or his Vo⯑tarys, have met with what they call Seminal Animalcula in it: for which rea⯑ſon it would appear that the Urine is no beloved Habitation of theirs.

Sixthly, The Serum of the Blood is not altogether ſo fit a Vehicle, for they having ſome ſmall Solidity, muſt be de⯑poſited in the Sediment, together with the Blood Globules, and ſo become in⯑viſible.

Seventhly, Neither could Leewenhoeck find them in the Saliva; for the Glands which ſtrain it off from the Blood, ſeem to have too narrow Ducts to ſuffer the Paſſage of either Infects or their Eggs. The diſagreeableneſs of both Bile and Urine to theſe little Animals, is fur⯑ther evident from this, that altho the ſtrainers of both Liver and Kidneys ſeem larger and laxer than the teſticular Strain⯑ers, and might therefore be ſuppos'd to admit of theſe Inſects, yet are they rarely perceiv'd alive in theſe Liquors.

I ſhall now try to account for be ſe⯑veral ways how theſe Inſects are gene⯑rated in the Semen, and come to be re⯑poſited in the Veſiculae Seminales, when [23]Boys come to Puberty: And this will ſerve to illuſtrate, not only the Genera⯑tion of theſe, but of all other Inſects which are to be met with in human Bodies. Theſe ways I ſuppoſe to be chiefly three, viz. 1ſt, From our Crea⯑tion. 2ly, From our Propagation. 3ly, From our Suſtentation.

It's from the firſt two of theſe that we can account for Worms in the Bodies of Embrios, Foetus's, and Abortives: But the Generation of Inſects from our Crea⯑tion, I preſume to be this, That altho God, at Man's firſt Creation, did not directly and purpoſely ſow the Seeds of ſuch an ineradicable Vermin in human Bodies; yet Man's Body being made of Earth (whether Clay, Duſt or Aſhes, it's not material to our Deſign) towards the Evening of the ſixth Day, when he had ended all his other Works; the Earth not only then abounded with Inſects and Ova, but having been at firſt created and furniſh'd with the Seeds of all theſe, there muſt fall ſome of the minuter of them to the ſhare of that part of Matter, which went to the Compoſitum of the human Machine. And theſe might not only be a Seed for the Generation and Propa⯑gation of theſe Inſects in the firſt Man's Body, but ſerve for the Seeds of a laſting Progeny in all his Poſterity, who ſhall [24]deſcend from him. 'Tis ſurprizing to ſee how little trouble the Antients gave them⯑ſelves in inquiring into the Cauſe of Ver⯑min in animal Bodies; they were ſatisfy'd that they had ſolv'd the doubt at once, by ſaying, that Inſects were form'd from themſelves, out of a certain putrid mat⯑ter, by Heat and Motion: But they ne⯑ver regarded the Deſtruction of their Hy⯑potheſis, when they might obſerve that the Generation of Inſects, and all other Creatures, was always alike the ſame; for if ſlimy and putrid Matter could give Form and Life to any Creature, it were ridiculous to expect that the Species ſhould ſtill be of the Sort, and always keep one Form and Shape. According to their Notion, where there is plenty of Slime and an agreeable Warmth, Men might with Horror and Danger look on, and ſee ſtrange and prodigious Monſters daily ariſe out of this Heap of Putrifac⯑tion, ready to devour the Beholders, and the Food deſign'd for their Proviſion. Mercurialis, either perſuaded of the Folly of this Suppoſition, or affecting to be ſingular, fled to occult Qualities, and celeſtial Powers, which by the Mediation of proximate Cauſes, form'd Animals: But he could not diſpute, whether this was the Facultas fortuita Galeni, or the powerful Factor calcodea Avicennae, or [25] Plato's Anima Mundi: In the laſt Age the indefatigable Redi has demonſtrated, that the Generation of Animals and In⯑ſects is ſtill alike; and then all Philo⯑ſophers with unanimous conſent, baniſh'd the Notion of equivocal Generation, and aſſign'd Inſects the ſame Parents, viz. Ova: Of late appear'd the learned Va⯑liſnerius, who ſtrenuouſly contends that Worms in the human Body are coeval with Adam, and ſays that the Eggs of all Inſects that generate in Men, were pur⯑poſely created by God in the Body of the firſt Man, even when created in a State of Purity and Innocency. One great Difficulty which put him on coining this new Scheme, was to account from whence theſe Eggs came, and how they can be detain'd in human Bodies; for he thinks it equally dangerous to true Philo⯑ſophy, whether we believe that Animals are bred out of Corruption, or ſuppoſe a certain kind of Animals produc'd from the Eggs of others of a different Kind, and ſo confound their Species. Thus, ſays he, we give to ſome Inſects feign'd Fathers, and to others baſtard Children: What he chiefly builds his Argument upon, is, That we can find no Species of Inſects without us, to which we may fitly compare theſe Inſects bred within us; and then to eſtabliſh his Opinion be⯑yond [26]all Controverſy, he ſays, That the Inſects without us, as they are of dif⯑ferent Kinds, ſo they have their ſundry Habitations: Such as live in one kind of Earth will die in another; and on Shrubs and Trees, theſe who live on its Roots would pine on its Leaves; and thoſe who feed well on the Bark, would ſtarve on the Wood, Fruit, Leaves, &c. Tho it be not my Deſign to examine all this learned Man's Arguments, yet give me leave briefly to obſerve, en paſ⯑ſant, that as we meet with variety of In⯑fects without us, ſo are there different Kinds of Worms within us.

Secondly, We know that either Vege⯑tables or Animals, remov'd from their na⯑tural Soil to a very different Climate, and Nouriſhment, will in a few of their Ge⯑nerations be ſo much changed from their natural Appearances, that they will hard⯑ly be taken for the ſame; this is ſo commonly allow'd, that it needs no Proof.

Thirdly, The many Hiſtorys and Ob⯑ſervations of the Spawn of Frogs, Beetles, and other Inſects, having been unwarily ſwallow'd down with Meat or Drink, and generated in the Body, leaves no room to doubt but that the Ova of In⯑ſects ſwallow'd down will breed in us, and produce a Vermin which will live in us, tho depriv'd of the open Air, and [27]the common Food of its Species, ſuch as that we meet with in the Philoſo⯑phical Tranſactions of a Man's Girl at Sheffield, aged only three Months, who after ſwallowing greedily a Pint of Worm⯑wood Ale, ſhe vomited up three Hexa⯑podes, all very active and nimble; theſe, Dr. Liſter ſays, would have chang'd to Beetles: And alſo the Man's Son, who after a long and grievous Pain of the Sto⯑mach, vomited up ſeveral ſtrange Worms, in the ninth Year of his Age; theſe Worms, ſays Dr. Liſter, were Cater⯑pillars with 14 Legs, for he had many times ſeen of the ſame Kind on Plants; and no doubt (ſays he) theſe would in due time (if the Place had not hindred) have ſhrunk into Chryſalis's, and chang'd into Moths.

Fourthly, There may be ſome un⯑heeded Circumſtances in the Generation and Production of ſeveral Inſects, that will not only come up to, but exceed the Diſſimilitude of theſe Inſects bred in in our Bodys, to theſe of the ſame Kind without us. I ſhall inſtance in ſome that we know, E. gr. Who wou'd believe that that fine flying Inſect the Lybella ſhould be generated like a Tadpole under Water, wrapt up in a Membrane till ſhe be near ready to leave that Element, and appear in a more glorious Dreſs in the open Air? [28]Who would expect that great Caterpillars ſhould ſometimes produce two or three, or a whole Swarm of Ichneumones, an Inſect with four Wings, Antennae, like a Bee? &c. Dr. Liſter, Apr. 2. 1671. dif⯑fected ſome black Beetles which were caſt up in his Garden, and found live hair Worms in their Bellys, which crept out and crawl'd, when the Beetle's Belly was cut up; they were ſome Inches long, and about the thickneſs of a Hog's Briſtle. Theſe are what have been taken by the Vulgar for Horſe-hairs turning into Eels, or animated Bodys in Water. Strange it is alſo that the wild Bees which breed in old Willows, if theſe Bees, Maggots or Nym⯑phae happen to miſcarry, they breed, 1ſt, little Hexapodes, which produce Beetles: 2ly, Maggots, which produce Flys: 3ly, Mites, &c. And what more wonderful Metamorphoſis can we imagine than that of a Caterpillar into a Butterfly, and of a Butterfly into a Caterpillar again? We have alſo ſufficient Experience that ſeveral Inſects live caſually and promiſcuouſly on Herbs, Leaves, Flowers, and Fruits.

Fifthly, Inſects from Ova taken into our Bodys, may generate and live there, having, during their Generation, been nouriſh'd with the Juices of our Bodys, and afterwards fed with the ſame. And in⯑deed it's more reaſonable to think that the [29]Inſects of our Bodys are bred from Ova, than from Vermin ſwallow'd down alive; for I have known ſome conſumptive Per⯑ſons ſwallow many ſmall Frogs alive, without any Generation thereof, or in⯑convenience therefrom. But a young Fellow in the Neighbourhood where I liv'd, had not ſo good Fate; for he in the latter end of February, careleſly drank ſome Water, wherein was Frog⯑ſpawn, and had therefrom generated in his Body a fine fry of young Frogs, whereby he was emaciated and reduced to a living Ghoſt; and when neither the greateſt Bitters nor ſtrong Purges could be of any ſervice to him, there were given him ſtrong Vomits of white Hellebore, which raiſed ſuch violent Spaſms and Con⯑vulſions in the muſcular Fibres of his Sto⯑mach and Inteſtines, that the nauſeous deſtructive Vermin were forc'd to quit their hold and be thrown up. So there's no doubt but ſeveral Inſects which are ſwallow'd alive by us, will live and breed: and for this reaſon it is that wiſe Nature has taught Herons and ſome other Fowls, which live much on Worms and Inſects, to draw them often thro' their Bills, and pinch them till they are dead before they ſwallow them. Another great Difficulty with Valiſnerius, is. That there have been many kinds of Inſects found in hu⯑man [30]Bodys, none of whoſe Species were ever ſeen abroad in the World. But to this may be reply'd, 1. That the diffe⯑rent Soil may very much alter the Crea⯑ture from thoſe of the ſame kind without us. 2. Some Creatures have very diffe⯑rent Appearances, according to the ſundry Stages of their Growth: thus Bees are firſt white Maggots, then Bees; Frogs are firſt Tadpoles and ſwim like ſmall Fiſh in the Water; Ichneumones are firſt a kind of Tadpole, then a glorious flying Inſect, &c. I confeſs that ſometimes ſuch Ob⯑ſervers may be willing to flatter them⯑ſelves, and think they have ſeen Monſters, and ſo impoſe upon our Faith, when per⯑haps their great wonder may be only a little coagulated Blood, unnatural Ex⯑creſence or Polypus appearing, or cun⯑ningly repreſented by the dextrous Ope⯑rator in ſuch a Shape; for there is no ſuch thing as a new Creation of Animals or Inſects of ſuch an unknown Species; ſuch things are proper only to amuſe Idiots, Half-wits and Children, who can be pre⯑vail'd upon to believe a ſpontaneous Ge⯑neration in oppoſition to God, Reaſon and Obſervation. Theſe are the chief of Valiſnerius's Difficultys, which drive him back to Man's firſt Creation for the Ori⯑gni of Inſects in human Bodys; but we [31]ſee there's no ſuch Difficulty in them, as to challenge our Compliance with him.

Secondly, Another way how Inſects are generated in human Bodys, is, from the Seed it ſelf: for conſider we that the Se⯑men whereby Man is propagated, is ſaid to abound with live Inſects; and can we imagine that Creatures of ſuch vigorous, agile and minute Bodys, cannot penetrate and make their way thro' the interſtices of the dilated Membranes of the Ovum Foeminaeum, get into the Rudiments of the Embrio, be ſhut up in its Veſſels, and be mix'd with its Fluids, circulate with the Blood and Juices, live, lay their Eggs, and breed in the Body of the Foetus? The Animalcula make up the ſubtileſt Part of the Maſculine Semen; and it would be ridiculous to aſſert, that the ſluggiſh viſcid Part made its way into the Ovum, but the more ſubtile and active Part did not: Therefore the Repletion of the Seed with theſe, is ſufficient Foundation for future Generation, and a laſting Progeny of the kind in every Man and Woman during Life. Now to aſſert the Deſtruction of them in the Womb, were abſurd, ſeeing the Embrio is nouriſh'd with the fineſt Juices of the Mother's Body, which muſt make as agreeable a repaſt for them, as they can meet with afterwards in the Bodys of Adults.

Thirdly, The laſt way how I ſuppoſe the Inſects in animal Bodys do come, is, from our Suſtentation or Food; and this I divide again into three, viz. That where⯑with we are nouriſh'd in the Womb. 2. That wherewith we are fed in our Infancy, to wit, the Mother's Milk: and, 3. That which preſerves human Life ever after.

As to the firſt of theſe: Let us remem⯑ber that the Embrio in the Ʋterus is not only ſurrounded with, but fed by the Mo⯑ther's Juices, eſpecially thoſe in the Am⯑nios, in which are diſcover'd multitudes of Animalcula of ſeveral ſorts: And theſe, together with the Fluid wherein they live and ſport, getting into the Body and Veſ⯑ſels of the Foetus, will leave the Seeds of a Vermin, which ſhall never be extirpated. And from this may Inſects of ſundry kinds be found in the Bodys of Abortives. Now that the Child receives ſome of its Nouriſhment from the Liquor contain'd in the Amnios, the learned and curious Heiſter, Profeſſor of Anatomy at Altorf, has fully prov'd. But ſuppoſe the Child had no part of its Nouriſhment from theſe Juices, yet is there not a conſtant Circulation of Fluids from Mother to Child, and back from the Child to the Mother again? And are there not mul⯑titudes of Inſects and Ova in the human [33]Blood, tho its globular Parts render them inviſible to us? But,

Secondly, Suppoſe the Child ſhould come into the World, free from all man⯑ner of Inſects or Ova (which yet is nei⯑ther probable nor poſſible) after its Birth, is not much of its Food Milk? and are we not ſatisfy'd that the Mother's Milk abounds with Animalcula? and is not here ſufficient Cauſe for the Generation of all theſe Myriads in the human Body, whilſt as yet an Infant? How are we to expect that the Infant's Body ſhould be ca⯑pable to deſtroy all that Vermin, ſince they eſcap'd the ſtrong Attrition of the Mother's Stomach, Lungs, and Muſcles, all which are ſtronger in the Mother, than it's reaſonable to expect in the In⯑fant?

The laſt Cauſe I aſſign'd for the In⯑geſtion and Generation of Inſects and Ova into our Bodys, was by thoſe Means which are the Preſervation and Support of human Life, during the remaining Courſe of our time; and theſe are our Meat, Drink and Air: I ſay, from the Mixture of the Ova of Inſects with theſe. For altho it be ſuppos'd that when we are Adult, our Stomachs are able to at⯑tenuate and digeſt, not only the ingeſted A⯑liments, but alſo many of theſe Ova, which [34]muſt undergo the common Fate of At⯑trition and Comminution of their Par⯑ticles; but in Youth, eſpecially in Child⯑hood, the Stomach is weak, and the Ova eſcape, and generate Inſects in our Bodys. To this Cauſe may be added Children's irregular way of eating, often cramming down new Food, before the former was fully digeſted, and got out of the Sto⯑mach, whereby their Chyle muſt be coarſe and unprepar'd: a Viſcidity will ſubſide and line the inſide of the Guts, and be⯑come a fit Neſt for the Ova to take up their Reſidence in, and become a Filter to the Chyle, whereby the Ova of larger Inſects are detain'd, hatch'd, come to Life, generate, and become the Parents of an innumerable Progeny. Childrens incapa⯑city for Exerciſe contributes its ſhare to this; for their Solids are weak and lax, and then their Food is not only ſuch as abounds with Ova, but as the Parents of theſe Ova have found it a proper Recep⯑tacle for them, ſo their Offspring muſt find it exceedingly agreeable, viz. Milk, and the farinaceous Foods. I could aſſign other Cauſes, but theſe are ſufficient. However, I deny that when we are A⯑dult, our Stomachs are ſo very capable of attenuating, breaking, and digeſting the Particles of the Ova; for that is more [35]properly the Uſe of the Lungs, and the Effect of muſcular Motion, to divide and grind down ſuch Moleculae, or ſmall Bo⯑dys. But when all theſe have exerted their utmoſt Force, ſtill great Numbers of both Ova and Animalcula eſcape all their Shocks; as is evident, 1ſt, From the Ge⯑neration of Worms and Inſects in all parts of adult Bodys: 2ly. The Production of ſuch Myriads of Inſects in dead Bodys in few Days, as quickly eat it up, eſpecially if the Seaſon be very warm. Now that all theſe are Ova ſwimming in the Air, and falling upon, and breeding in dead Carcaſes, I deny: for altho theſe Inſects may ſeize upon it externally, yet far greater Numbers are produc'd from Ova and Inſects within the Carrion it ſelf. This I am ſatisfy'd of from theſe Obſer⯑vations. 1ſt, I have found incredible Num⯑bers of theſe little Animals, generated and living in the fleſhy Parts of dead Bodys, where both Skin and Scarf Skin have been ſound and intire: this I have ſeen, eſpe⯑cially in dead Fiſh, upon the Shore in Summer-time. 2ly, Take a dead Body in a hot Summer Seaſon, and cover it up from the Air, and you ſhall find that this will not wholly prevent the Growth of Inſects, only it will be longer before they breed, and arrive at their Perfection; and [36]no doubt fewer in Number, from the De⯑privation of adventitious Ova and Ani⯑malcula from the Air. 3ly, The Con⯑ſumption of human Bodys in the Grave, is a plain Proof of this; for let the Coffin be contriv'd never ſo cloſe, or the Grave deep, yet great Numbers of Ver⯑min generate in the Body: Here the deep Interment prevents the Acceſſion or Ad⯑dition of Ova from the Air, and the cloſeneſs of the Coffin hinders their get⯑ting in from the Earth; for I found in a Skull newly digg'd up out of a deep Grave (which had not been many Years ſhut up) a great Multitude of ſmall Worms of dif⯑ferent kinds, tho the Coffin was cloſe and ſound, till broken by the Sexton. I had lately under my care a Woman who void⯑ed, every Day by Stool, a Multitude of Aſcarides; ſhe was then paſt 40 Years of Age, and had been accuſtom'd to this Evacuation every Morning for ſeveral Years paſt. I was acquainted with a Gentleman, who diſcharg'd every Morn⯑ing at Stool many large Knots of them clean before the Excrements, and yet both enjoy'd a good State of Health, had a good Appetite and Digeſtion: The firſt I recover'd by preſcribing a tedious Courſe of Bitters, with daily Exerciſe; and the laſt by the Chalybeat Waters. I hope it [37]cannot be deny'd, that Dogs have as ſtrong a Digeſtion as moſt Animals, and yet they are never free from theſe Inſects. This I think is ſufficient to invalidate the Strength of their Arguments, who affirm that the Force of adult Stomachs hinders the Generation of Worms, by breaking and grinding down their Eggs.

But now it remains in the laſt place, That I ſhow how I ſuppoſe theſe Animal⯑cula to come at the Seminal Bladders of Youth, when come to Puberty; and that is, (ſuppoſing them to come from with⯑out) the Number of Veſſels in Infants or Embrios is much greater than in Adults: as Children advance in Years, tho the greater Veſſels lengthen out and grow, yet the leaſt become more compact, their Diameters ſhorten, the quantity of Fluids admitted is ſtill leſs, till at laſt they refuſe all Acceſs to the Fluids, then cloſe up, grow together, and are changed into mi⯑nute Fibres, which requiring leſs Space, give more Liberty to the larger Veſſels to expand themſelves; their Compreſſion being leſſen'd, their Canals are enlarg'd, they allow more and larger Particles of Fluids to enter their Orifices, and move along their Tubes; the Membranes of the Veſſels being yet dilatable, and the contain'd Liquor preſſing Ʋndiquaque, the [38]Diameters of the Veſſels are lengthen'd, and their Orifices and Cavitys are propor⯑tionably widened, and are capable to ad⯑mit Particles of larger Diameters than they could formerly receive; amongſt which, not only Ova, but minute Inſects get along. And this appears to be truly the Caſe of the teſticular Strainers; for during Infancy, the natural Narrowneſs of theſe Pipes, and that increas'd by innumerable ſmall open Veſſels, (which afterwards va⯑niſh into ſolid Fibres) render the Tubes ſo exceedingly ſmall, that only ſo much inſipid Humour and Nouriſhment is ſuffer'd to enter, as ſuffices to keep open their Cavity, and nouriſh their Parts. But when both their Cavity naturally increas'd, and the ſmall Veſſels which wedge them in on every ſide have loſt their Cavity, then not only a greater Quantity of Liquor will paſs them, but Fluids conſiſting of larger Particles and Ova together with them. 2ly, We ſhall add hereto the dif⯑ferent ſorts of Animalcula found in Water; Dr. Hook ſays, that from his Microſcopial Obſervations, eight Millions two Hun⯑dred and eighty Thouſand of living Crea⯑tures may be ſeen in one Drop of Water. And as theſe had been too few, when he had procured finer Glaſſes, they not only magnified theſe he had formerly diſcover'd [39]to a very great Magnitude, but obſerv'd others much leſs than what he had for⯑merly ſeen, and ſome of them ſo minute, that Millions of Millions of them might be contain'd in one Drop of Water. Now if we conſider the State of the Teſticles of Youth arriv'd at Puberty, I ſee no Difficulty why we may not allow the Ova of theſe little Animals to paſs, and even the generated Animalcula themſelves may make way, and be driven thro' all the Turnings and Windings of the Teſticles, till they come at the deferent Veſſels, and Seminal Bladders. How improbable is it to expect that the Stomach ſhould exert any conſiderable Force upon the Ova of ſuch Inſects? 3ly, Another Preſumption that the Cavity of the Teſticular Glands is the Occaſion of the Admiſſion of theſe Gueſts, is, becauſe the mammillary Glands of the Breaſts, which ſeparate the Milk from the Blood, give ready Paſſage to prodigious Numbers of theſe Inſects or their Ova, which may readily be diſcover'd by the help but of ordinary Glaſſes. Thus I have explain'd the Manner of the Gene⯑ration of Inſects in human Bodys; it now remains that I ſhould treat of the uſe of theſe Seminal Worms, and enquire whe⯑ther they are reaſonably to be reputed the Rudiments of a human Foetus, or [40]whether each of them be an entire and perfect Man, as Leewenhoeck and his Followers teach and believe. But this would protract the preſent Diſcourſe far beyond its deſign'd Bounds: wherefore I ſhall defer this Inquiry to another Op⯑portunity.