Micrographia, by Robert Hooke

Observ. xx. Of blue Mould, and of the first Principles of Vegetation arising from Putrefaction.

The Blue and White and several kinds of hairy mouldy spots, which are observable upon divers kinds of putrify'd bodies, whether Animal substances, or Vegetable, such as the skin, raw or dress'd, flesh, bloud, humours, milk, green Cheese, &c. or rotten sappy Wood, or Herbs, Leaves, Barks, Roots, &c. of Plants, are all of them nothing else but several kinds of small and variously figur'd Mushroms, which, from convenient materials in those putrifying bodies, are, by the concurrent heat of the Air, excited to a certain kind of vegetation, which will not be unworthy our more serious speculation and examination, as I shall by and by shew. But, first, I must premise a short description of this Specimen, which I have added of this Schem. 12.
Fig. 1.
Tribe, in the first Figure of the XII. Scheme, which is nothing else but the appearance of a small white spot of hairy mould, multitudes of which I found to bespeck & whiten over the red covers of a small book, which, it seems, were of Sheeps skin, that being more apt to gather mould, even in a dry and clean room, then other leathers. These spots appear'd, through a good Microscope, to be a very pretty shap'd Vegetative body, which, from almost the same part of the Leather, shot out multitudes of small long cylindrical and transparent stalks, not exactly streight, but a little bended with the weight of a round and white knob that grew on the top of each of them; many of these knobs I observ'd to be very round, and of a smooth surface, such as A, A, &c. others smooth likewise, but a little oblong, as B; several of them a little broken, or cloven with chops at the top, as C; others flitter'd as 'twere, or flown all to pieces, as D, D. The whole substance of these pretty bodies was of a very tender constitution, much like the substance of the softer kind of common white Mushroms, for by touching them with a Pin, I found them to be brused and torn; they seem'd each of them to have a distinct root of their own; for though they grew neer together in a cluster, yet I could perceive each stem to rise out of a distinct part or pore of the Leather; some of these were small and short, as seeming to have been but newly sprung up, of these the balls were for the most part round, others were bigger, and taller, as being perhaps of a longer growth, and of these, for the most part, the heads were broken, and some much wasted, as E; what these heads contain'd I could not perceive; whether they were knobs and flowers, or seed cases, I am not able to say, but they seem'd most likely to be of the same nature with those that grow on Mushroms, which they did, some of them, not a little resemble.

Both their smell and taste, which are active enough to make a sensible impression upon those organs, are unpleasant and noisome.

I could not find that they would so quickly be destroy'd by the actual flame of a Candle, as at first sight of them I conceived they would be, but they remain'd intire after I had past that part of the Leather on which they stuck three or four times through the flame of a Candle; so that, it seems they are not very apt to take fire, no more then the common white Mushroms are when they are sappy.

There are a multitude of other shapes, of which these Microscopical Mushroms are figur'd, which would have been a long Work to have described, and would not have suited so well with my design in this Treatise, onely, amongst the rest, I must not forget to take notice of one that was a little like to, or resembled, a Spunge, consisting of a multitude of little Ramifications almost as that body does, which indeed seems to be a kind of Water-Mushrom, of a very pretty texture, as I else-where manifest. And a second, which I must not omit, because often mingled, and neer adjoining to these I have describ'd, and this appear'd much like a Thicket of bushes, or brambles, very much branch'd, and extended, some of them, to a great length, in proportion to their Diameter, like creeping brambles.

The manner of the growth and formation of this kind of Vegetable, is the third head of Enquiry, which, had I time, I should follow: the figure and method of Generation in this concrete seeming to me, next after the Enquiry into the formation, figuration; or chrystalization of Salts, to be the most simple, plain, and easie; and it seems to be a medium through which he must necessarily pass, that would with any likelihood investigate the forma informans of Vegetables: for as I think that he shall find it a very difficult task, who undertakes to discover the form of Saline crystallizations, without the consideration and prescience of the nature and reason of a Globular form, and as difficult to explicate this configuration of Mushroms, without the previous consideration of the form of Salts; so will the enquiry into the forms of Vegetables be no less, if not much more difficult, without the fore-knowledge of the forms of Mushroms, these several Enquiries having no less dependance one upon another then any select number of Propositions in Mathematical Elements may be made to have.

Nor do I imagine that the skips from the one to another will be found very great, if beginning from fluidity, or body without any form, we descend gradually, till we arrive at the highest form of a bruite Animal's Soul, making the steps or foundations of our Enquiry, Fluidity, Orbiculation, Fixation, Angulization, or Crystallization Germination or Ebullition, Vegetation, Plantanimation, Animation, Sensation, Imagination.

Now, that we may the better proceed in our Enquiry, It will be requisite to consider:

First, that Mould and Mushroms require no seminal property, but the former may be produc'd at any time from any kind of putrifying Animal, or Vegetable Substance, as Flesh, &c. kept moist and warm, and the latter, if what Mathiolus relates be true, of making them by Art, are as much within our command, of which Matter take the Epitomie which Mr. Parkinson has deliver'd in his Herbal, in his Chapter of Mushroms, because I have not Mathiolus now by me: Unto these Mushroms (saith he) may also be adjoyn'd those which are made of Art (whereof Mathiolus makes mention) that grow naturally among certain stones in Naples, and that the stones being digg'd up, and carried to Rome, and other places, where they set them in their Wine Cellars, covering them with a little Earth, and sprinkling a little warm water thereon, would within four days produce Mushroms fit to be eaten, at what time one will: As also that Mushroms may be made to grow at the foot of a wilde Poplar Tree, within four days after, warm water wherein some leaves have been dissolv'd shall be pour'd into the Root (which must be slit) and the stock above ground.

Next, that as Mushroms may be generated without seed, so does it not appear that they have any such thing as seed in any part of them; for having considered several kinds of them, I could never find any thing in them that I could with any probability ghess to be the seed of it, so that it does not as yet appear (that I know of) that Mushroms may be generated from a seed, but they rather seem to depend merely upon a convenient constitution of the matter out of which they are made, and a concurrence of either natural or artificial heat.

Thirdly, that by several bodies (as Salts and Metals both in Water and in the air, and by several kinds of sublimations in the Air) actuated and guided with a congruous heat, there may be produc'd several kinds of bodies as curiously, if not of a more compos'd Figure; several kinds of rising or Ebulliating Figures seem to manifest; as witness the shooting in the Rectification of spirits of Urine, Hart-horn, Bloud, &c. witness also the curious branches of evaporated dissolutions, some of them against the sides of the containing Jar: others standing up, or growing an end, out of the bottom, of which I have taken notice of a very great variety. But above all the rest, it is a very pretty kind of Germination which is afforded us in the Silver Tree, the manner of making which with Mercury and Silver, is well known to the Chymists, in which there is an Ebullition or Germination, very much like this of Mushroms, if I have been rightly inform'd of it.

Fourthly, I have very often taken notice of, and also observ'd with a Microscope, certain excrescencies or Ebullitions in the snuff of a Candle, which, partly from the sticking of the smoaky particles as they are carryed upwards by the current of the rarify'd Air and flame, and partly also from a kind of Germination or Ebullition of some actuated unctuous parts which creep along and filter through some small string of the Week, are formed into pretty round and uniform heads, very much resembling the form of hooded Mushroms, which, being by any means expos'd to the fresh Air, or that air which encompasses the flame, they are presently lick'd up and devour'd by it, and vanish.

The reason of which Phænomenon seems to me, to be no other then this:

That when a convenient thread of the Week is so bent out by the sides of the snuff that are about half an Inch or more, remov'd above the bottom, or lowest part of the flame, and that this part be wholly included in the flame; the Oyl (for the reason of filtration, which I have elsewhere rendred) being continualy driven up the snuff is driven likewise into this ragged bended-end, and this being remov'd a good distance, as half an Inch or more, above the bottom of the flame, the parts of the air that passes by it, are already, almost satiated with the dissolution of the boiling unctuous steams that issued out below, and therefore are not onely glutted, that is, can dissolve no more then what they are already acting upon, but they carry up with them abundance of unctuous and sooty particles, which meeting with that rag of the Week, that is plentifully fill'd with Oyl, and onely spends it as fast as it evaporates, and not at all by dissolution or burning, by means of these steamy parts of the filterated Oyl issuing out at the sides of this ragg, and being inclos'd with an air that is already satiated and cannot prey upon them nor burn them, the ascending sooty particles are stay'd about it and fix'd, so as that about the end of that ragg or filament of the snuff, whence the greatest part of the steams issue, there is conglobated or fix'd a round and pretty uniform cap, much resembling the head of a Mushrom, which, if it be of any great bigness, you may observe that its underside will be bigger then that which is above the ragg or stem of it; for the Oyl that is brought into it by filtration, being by the bulk of the cap a little shelter'd from the heat of the flame, does by that means issue as much out beneath from the stalk or downwards, as it does upwards, and by reason of the great access of the adventitious smoak from beneath, it increases most that way. That this may be the true reason of this Phænomenon, I could produce many Arguments and Experiments to make it probable: As,

First, that the Filtration carries the Oyl to the top of the Week, at least as high as these raggs, is visible to one that will observe the snuff of a burning Candle with a Microscope, where he may see an Ebullition or bubbling of the Oyl, as high as the snuff looks black.

Next, that it does steam away more then burn; I could tell you of the dim burning of a Candle, the longer the snuff be which arises from the abundance of vapours out of the higher parts of it.

And, thirdly, that in the middle of the flame of the Candle, neer the top of the snuff, the fire or dissolving principle is nothing neer so strong, as neer the bottom and out edges of the flame, which may be observ'd by the burning asunder of a thread, that will first break in those parts that the edges of the flame touch, and not in the middle.

And I could add several Observables that I have taken notice of in the flame of a Lamp actuated with Bellows, and very many others that confirm me in my opinion, but that it is not so much to my present purpose, which is onely to consider this concreet in the snuff of a Candle, so farr as it has any resemblance of a Mushrom, to the consideration of which, that I may return, I say, we may also observe:

In the fifth place, that the droppings or trillings of Lapidescent waters in Vaults under ground, seem to constitute a kind of petrify'd body, form'd almost like some kind of Mushroms inverted, in so much that I have seen some knobb'd a little at the lower end, though for the most part, indeed they are otherwise shap'd, and taper'd towards the end; the generation of which seems to be from no other reason but this, that the water by soaking through the earth and Lime (for I ghess that substance to add much to it petrifying quality) does so impregnate it self with stony particles, that hanging in drops in the roof of the Vault, by reason that the soaking of the water is but slow, it becomes expos'd to the Air, and thereby the outward part of the drop by degrees grows hard, by reason that the water gradually evaporating the stony particles neer the outsides of the drop begin to touch, and by degrees, to dry and grow closer together, and at length constitute a crust or shell about the drop; and this soaking by degrees, being more and more supply'd, the drop grows longer and longer, and the sides harden thicker and thicker into a Quill or Cane, and at length, that hollow or pith becomes almost stop'd up, and solid: afterwards the soaking of the petrifying water, finding no longer a passage through the middle, bursts out, and trickles down the outside, and as the water evaporates, leaves new superinduc'd shells, which more and more swell the bulk of those Iceicles, and because of the great supply from the Vault, of petrifying wafer, those bodies grow bigger and bigger next to the Vault, and taper or sharpen towards the point; for the access from the arch of the Vault being but very slow, and consequently the water being spread very thinly over the surface of the Iceicle, the water begins to settle before it can reach to the bottom, or corner end of it; whence, if you break one of these, you would almost imagine it a stick of Wood petrify'd, it having so pretty a resemblance of pith and grain, and if you look on the outside of a piece, or of one whole, you would think no less, both from its vegetable roundness and tapering form; but whereas all Vegetables are observ'd to shoot and grow perpendicularly upwards, this does shoot or propend directly downwards.

By which last Observables, we see that there may be a very pretty body shap'd and concreeted by Mechanical principles, without the least shew or probability of any other seminal formatrix.

And since we find that the great reason of the Phænomena of this pretty petrifaction, are to be reduc'd from the gravity of a fluid and pretty volatil body impregnated with stony particles, why may not the Phænomena of Ebullition or Germination be in part possibly enough deduc'd from the levity of an impregnated liquor, which therefore perpendicularly ascending by degrees, evaporates and leaves the more solid and fix'd parts behind in the form of a Mushrom, which is yet further diversify'd and specificated by the forms of the parts that impregnated the liquor, and compose or help to constitute the Mushrom.

That the foremention'd Figures of growing Salts, and the Silver Tree, are from this principle, I could very easily manifest, but that I have not now a convenient opportunity of following it, nor have I made a sufficient number of Experiments and Observations to propound, explicate, and prove so usefull a Theory as this of Mushroms: for, though the contrary principle to that of petrify'd Iceicles may be in part a cause, yet I cannot but think, that there is somewhat a more complicated caufe, though yet Mechanical, and possible to be explain'd.

We therefore have further to enquire of it, what makes it to be such a liquor, and to ascend, whether the heat of the Sun and Air, or whether that firmentiation and putrifaction, or both together; as also whether there be not a third or fourth; whether a Saline principle be not a considerable agent in this business also as well as heat; whether also a fixation, precipitation or settling of certain parts out of the aerial menstruum may not be also a considerable coadjutor in the business. Since we find that many pretty beards stiriæ of the particles of Silver may be precipitated upon a piece of Brass put into a solution of Silver very much diluted with fair water, which look not unlike a kind of mould or hoar upon that piece of metal; and the hoar frost looks like a kind of mould; and whether there may not be several others that do concurr to the production of a Mushrom, having not yet had sufficient time to prosecute according to my desires, I must referr this to a better opportunity of my own, or leave and recommend it to the more diligent enquiry and examination of such as can be masters both of leisure and conveniencies for such an Enquiry.

And in the mean time, I must conclude, that as far as I have been able to look into the nature of this Primary kind of life and vegetation, I cannot find the least probable argument to perswade me there is any other concurrent cause then such as is purely Mechanical, and that the effects or productions are as necessary upon the concurrence of those causes as that a Ship, when the Sails are hoist up, and the Rudder is set to such a position, should, when the Wind blows, be mov'd in such a way or course to that or t'other place; Or, as that the brused Watch, which I mention in the description of Moss, should, when those parts which hindred its motion were fallen away, begin to move, but after quite another manner then it did before.

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