Micrographia, by Robert Hooke

Observ. xxv. Of the stinging points and juice of Nettles, and some other venomous Plants.

A Nettle is a Plant so well known to every one, as to what the appearance of it is to the naked eye, that it needs no description; and there are very few that have not felt as well as seen it; and therefore it will be no news to tell that a gentle and slight touch of the skin by a Nettle, does oftentime, not onely create very sensible and acute pain, much like that of a burn or scald, but often also very angry and hard swellings and inflamations of the parts, such as will presently rise, and continue swoln divers hours. These observations, I say, are common enough; but how the pain is so suddenly created, and by what means continued, augmented for a time, and afterwards diminish'd, and at length quite exstinguish'd, has not, that I know, been explain'd by any.

And here we must have recourse to our Microscope, and that will, if almost any part of the Plant be looked on, shew us the whole surface of it very thick set with turn-Pikes, or sharp Needles, of the Schem. 15.
Fig. 1.
shape of those represented in the 15. Scheme and first Figure by AB, which are visible also to the naked eye; each of which consists of two parts very distinct for shape, and differing also in quality from one another. For the part A, is shaped very much like a round Bodkin, from B tapering till it end in a very sharp point; it is of substance very hard and stiff, exceedingly transparent and cleer, and, as I by many trials certainly found, is hollow from top to bottom.


This I found by this Experiment, I had a very convenient Microscope with a single Glass which drew about half an Inch, this I had fastned into a little frame, almost like a pair of Spectacles, which I placed before mine eyes, and so holding the leaf of a Nettle at a convenient distance from my eye, I did first, with the thrusting of several of these bristles into my skin, perceive that presently after I had thrust them in I felt the burning pain begin; next I observ'd in divers of them, that upon thrusting my finger against their tops, the Bodkin (if I may so call it) did not in the least bend, but I could perceive moving up and down within it a certain liquor, which upon thrusting the Bodkin against its basis, or bagg B, I could perceive to rise towards the top, and upon taking away my hand, I could see it again subside, and shrink into the bagg; this I did very often, and saw this Phænomenon as plain as I could ever see a parcel of water ascend and descend in a pipe of Glass. But the basis underneath these Bodkins on which they were fast, were made of a more pliable substance, and looked almost like a little bagg of green Leather, or rather resembled the shape and surface of a wilde Cucumber, or cucumeris asinini, and I could plainly perceive them to be certain little baggs, bladders, or receptacles full of water, or as I ghess, the liquor of the Plant, which was poisonous, and those small Bodkins were but the Syringe-pipes, or Glyster-pipes, which first made way into the skin, and then served to convey that poisonous juice, upon the pressing of those little baggs, into the interior and sensible parts of the skin, which being so discharg'd, does corrode, or, as it were, burn that part of the skin it touches; and this pain will sometimes last very long, according as the impression is made deeper or stronger.

The other parts of the leaf or surface of the Nettle, have very little considerable, but what is common to most of these kinds of Plants, as the ruggedness or indenting, and hairiness, and other roughnesses of the surface or out-side of the Plant, of which I may say more in another place. As I shall likewise of certain little pretty cleer Balls or Apples which I have observed to stick to the sides of these leaves, both on the upper and under side, very much like the small Apples which I have often observ'd to grow on the leaves of an Oak call'd Oak-apples which are nothing but the Matrices of an Infect, as I elsewhere shew.

The chief thing therefore is, how this Plant comes, by so slight a touch, to create so great a pain; and the reason of this seems to be nothing else, but the corrosive penetrant liquor contain'd in the small baggs or bladders, upon which grow out those sharp Syringe-pipes, as I before noted; and very consonant to this, is the reason of the pain created by the sting of a Bee, Wasp, &c. as I elsewhere shew: For by the Dart, which is likewise a pipe, is made a deep passage into the skin, and then by the anger of the Fly, is his gally poisonous liquor injected; which being admitted among the sensible parts, and so mix'd with the humours or stagnating juices of that part, does create an Ebullition perhaps, or effervescens, as is usually observ'd in the mingling of two differing Chymical saline liquors, by which means the parts become swell'd, hard, and very painfull; for thereby the nervous and sensible parts are not onely stretch'd and strain'd beyond their natural tone, but are also prick'd, perhaps, or corroded by the pungent and incongruous parts of the intruded liquor.

And this seems to be the reason, why Aqua fortis, and other saline liquors, if they come to touch the sensitive parts, as in a cut of the skin, or the like, do so violently and intollerably excruciate and torment the Patient. And 'tis not unlikely, but the Inventors of that Diabolical practice of poisoning the points of Arrows and Ponyards, might receive their first hint from some such Instance in natural contrivances, as this of the Nettle: for the ground why such poison'd weapons kill so infallibly as they do, seems no other then this of our Nettle's stinging; for the Ponyard or Dart makes a passage or entrance into the sensitive or vital parts of the body, whereby the contagious substance comes to be dissolv'd by, and mix'd with the fluid parts or humours of the body, and by that means spreads it self by degrees into the whole liquid part of the body, in the same manner, as a few grains of Salt, put into a great quantity of Water, will by degrees diffuse it self over the whole.

And this I take to be the reason of killing of Toads, Frogs, Effs, and several Fishes, by strewing Salt on their backs (which Experiment was shewn to the Royal Society by a very ingenious Gentleman, and a worthy Member of it) for those creatures having always a continual exsudation, as it were, of slimy and watry parts, sweating out of the pores of their skin, the saline particles, by that means obtain a vehicle, which conveys them into the internal and vital parts of the body.

This seems also to be the reason why bathing in Mineral waters are such soveraign remedies for multitudes of distempers, especially chronical; for the liquid & warm vehicles of the Mineral particles, which are known to be in very considerable quantities in those healing baths, by the body's long stay in them, do by degrees steep and insinuate themselves into the pores and parts of the skin, and thereby those Mineral particles have their ways and passages open'd to penetrate into the inner parts, and mingle themselves with the stagnant juices of the several parts; besides, many of those offensive parts which were united with those stagnant juices, and which were contrary to the natural constitution of the parts, and so become irksome and painfull to the body, but could not be discharged, because Nature had made no provision for such accidental mischiefs, are, by means of this soaking, and filling the pores of the skin with a liquor, afforded a passage through that liquor that fills the pores into the ambient fluid, and thereby the body comes to be discharged.

So that 'tis very evident, there may be a good as well as an evil application of this Principle. And the ingenious Invention of that Excellent person, Doctor Wren of injecting liquors into the veins of an Animal, seems to be reducible to this head: I cannot stay, nor is this a fit place, to mention the several Experiments made of this kind by the most incomparable Mr. Boyle, the multitudes made by the lately mention'd Physician Doctor Clark, the History whereof, as he has been pleas'd to communicate to the Royal Society, so he may perhaps be prevail'd with to make publique himself: But I shall rather hint, that certainly, if this Principle were well consider'd, there might, besides the further improving of Bathing and Syringing into the veins, be thought on several ways, whereby several obstinate distempers of a humane body, such as the Gout, Dropsie, Stone, &c. might be master'd, and expell'd; and good men might make as good a use of it, as evil men have made a perverse and Diabolical.

And that the filling of the pores of the skin with some fluid vehicle, is of no small efficacy towards the preparing a passage for several kinds of penetrant juices, and other dissoluble bodies, to insinuate themselves within the skin, and into the sensitive parts of the body, may be, I think, prov'd by an Instance given us by Bellonius, in the 26. Chapter of the second Book of his Observations, which containing a very remarkable Story I have here transcrib'd: Cum Chamæleonis nigri radices (says he) apud Pagum quendam Livadochorio nuncupatum erui curaremus, plurimi Græci & Turcæ spectatum venerunt quid erueremus, eas vero frustulatim secabamus, & filo trajiciebamus ut facilius exsiccari possent. Turcæ in eo negotio occupatos nos videntes, similiter eas radices tractare & secare voluerunt: at cum summus esset æstus, & omnes sudore maderent, quicunque eam radicem manibus tractaverant sudoremque absterserant, aut faciem digitis scalpserant, tantam pruriginem iis locis quos attigerant postea senserunt, ut aduri viderentur. Chamæleonis enim nigri radix ea virtute pollet, ut cuti applicata ipsam adeo inflammet, ut nec squillæ, nec urticæ ullæ centesima parte ita adurent: At prurigo non adeo celeriter sese prodit. Post unam aut alteram porro horam, singuli variis faciei locis cutem adeo inflammatam habere cæpimus ut tota sanguinea videretur, atque quo magis eam confricabamus, tanto magis excitabatur prurigo. Fonti assidebamus sub platano, atque initio pro ludicro habebamus & ridebamus: at tandem illi plurimum indignati sunt, & nisi asseverassemus nunquam expertos tali virtute eam plantam pollere, haud dubie male nos multassent, Attamen nostra excusatio fuit ab illis facilitus accepta, cum eodem incommodo nos affectos conspicerent. Mirum sane quod in tantillo radice tam ingentem efficaciam nostro malo experti sumus.

By which observation of his, it seems manifest, that their being all cover'd with sweat who gather'd and cut this root of the black Chameleon Thistle, was the great reason why they suffer'd that inconvenience, for it seems the like circumstance had not been before that noted, nor do I find any mention of such a property belonging to this Vegetable in any of the Herbals I have at present by me.

I could give very many Observations which I have made of this kind, whereby I have found that the best way to get a body to be insinuated into the substance or insensible pores of another, is first, to find a fluid vehicle that has some congruity, both to the body to be insinuated, and to the body into whose pores you would have the other convey'd. And in this Principle lies the great mystery of staining several sorts of bodies, as Marble, Woods, Bones, &c. and of Dying Silks, Cloaths, Wools, Feathers, &c. But these being digressions, I shall proceed to:


Last updated Monday, March 17, 2014 at 16:42