Having examin’d and pursu’d the Degrees ofVegetationin theSeed, we find its two Lobes have here their utmost period; and, that having conveyed their Seminalities into theRadicleand into thePlume; these therefore as the Root and Trunk of the Plant still survive; Of these in their order we next proceed to speak; and first, of theRoot: whereof, as well as of theSeed, we must by Dissection inform our selves.
In Dissection of aRootthen, weshall find it with theRadicle, as the Parts of an old man with those of aFœtus, substantially one. The first Part occurring is its skin, the Original whereof is from the Seed: For that extream thin Cuticle which is spred over the Lobes of the Seed, and from thence over theRadicle, upon the shooting of theRadicleinto a Root, is co-extended, and becomes its Skin.
The next Part is theCortical Body; the Original whereof likewise is from the Seed; or theParenchyma, which is there common both to the Lobes andRadicle, being by Vegetation augmented and prolonged into theRoot, is here theCortical Body, or that which is sometimes called theBarque.
The Contexture of thisCortical Bodymay be well illustrated by that of aSponge, being a Body Porous, Dilative, and Pliable.Its Pores, as they are innumerable, so extream small. These Pores are not only susceptive of so much Moisture as to fill, but also to enlarge themselves, and so to dilate theCortical Bodywherein they are; which by the shriv’ling in thereof, by being expos’d to the Air, is also seen. In which dilatation many of its Parts becoming more lax and distant, and none of them suffering a solution of their continuity; ’tis a Body also sufficiently pliable; or, a most exquisitely fine-wrought Sponge.
The Extention of these Pores is much alike both by their length and breadth of the Root; which from the shrinking up of theCortical Body, in a piece of a cut Root, by the same dimensions, is argu’d.
The proportions of thisCortical Bodyare various: If thin, ’tis called aBarque; & thought to serveto no other end, than what is usually ascrib’d to it as aBarque; which is a narrow conceit: If a Bulky Body in comparison with that within it, as in the young Roots ofCychory,Asparagus, &c. ’tis here, because the fairest, therefore taken for the prime Part; which, though, as to Medicinal use, it is; yet, as to the private use of the Plant, not so. The Colour hereof, though it be originally white, yet in the continued growth of the Root, divers Tinctures, as yellow inDock, red inBistort, are thereinto introduced.
Next within this Part stands theLignous Body; the Original whereof, as of the two former, is from the Seed; or, theSeminal Rootsof both the Lobes, being united in theRadicle, and with itsParenchymaco-extended, is here in the Root theLignous Body.
The Contexture hereof is, in many of its parts, much more close than that of theCortical; and their Pores very different: For whereas those of theCorticalare infinitely numerous, these of theLignousare in comparison, nothing so. But these, although fewer, yet are they many of them more open, fair, and visible: as in a very thin Slice cut athwart the young Root of a Tree, and held up against the Light, is apparent: Yet not in all equally, inCoran-Tree, inGoosberry-Tree,&c.less; inOak,Plums, and especiallyDamascens, more; inElder,Vines, &c. more conspicuous. And as they are different in number and size, so also (whereon the numerousness of the Pores of theCortical Bodyprincipally depends) in their shape. For whereas those of theCortical Bodyare extended much alike both by the length and breadth of theRoot; these of theLignousare only by the length; which, especially inVinesand some otherRoots, is evident. Of these Pores, ’tis also observable, that although in all places of theRootthey are visible, yet most fair and open about theFibrous Extremitiesof someRoots(and in manyRootshigher) where there is no Pith. These Pores, as they shew in youngRootsof Trees,see inFig. 6, &7.
ThisLignous Bodylieth with all its Parts, so far as they are visible, in a Circle or Ring; yet are there divers extream small Fibres thence shooting, usually mixed with theCortical Body; and by the somewhat different colour of the saidCortical Bodywhere they stand, may be noted these Fibres; theCortical BodyandSkinall together, properly make theBarque.
The proportion betwixt thisLignous Bodyand theCortical, isvarious, as was said; yet in this, constant,sc.that in the fibrous, and smaller Parts of theRoot, theLignous Bodyis not only in compass, but in quantity the less; running like a slender Wyer or Nerve through the other surrounding it. They stand both together pyramidally, which is most common toInfant-Roots, but also to many other.
The next Part observable in theRoot, is theInsertment. The existence hereof, so far as we can yet observe, is sometimes in theRadicleof the Seed it self; I cannot say alwayes. As to its substantial nature, we are more certain; that it is the same with that of theParenchymaof theRadicle; being alwayes at least augmented, and so, in part, originated from theCortical Body, and so, at second hand, from the saidParenchyma: For in dissecting aRoot, we find,that theCortical Bodydoth not only environ theLignous, but is also wedg’d, and in many pieces inserted into it; and that the said inserted pieces, make not a meer Indenture, but transmit and shoot themselves quite through as far as the Pith; which in a thin Slice cut athwart theRootas so many lines drawn from the Circumference towards the Center, shew themselves.SeeFig. 6, &7.
The Pores of theInsertmentare sometimes, at least, extended somewhat more by the breadth of theRoot, as about the top of theRootofBoragemay be seen; and are thus different from those of theCortical Body, which are extended by the length and breadth much alike; and from those of theLignous, being only by its length.
The number and size of these Insertions are various. InHawthorn, and some others, and especiallyWillows, they are most extream small; inCherriesandPlumsthey are large; and inDamascensespecially, very fairly apparent. In theRootsof smallPlantsthey are generally more easily discoverable; which may lead to the observation of them in all.
These Insertions, although they are continuous through both the length and breadth of theRoot; yet not so in all Parts, but by the several shootings of theLignous Bodyare frequently intercepted. For of theLignous Bodyit is (here best) observable, That its several shootings, betwixt which theCorticalis inserted, are not throughout theRootwholly distinct; but that all along being enarch’d, theLignous Body, both in length and breadth, is thus disposed into Braces or Osculations. Betwixt these several shootings of theLignous Bodythus osculated, theCorticalshooting, and being also osculated answerably Brace for Brace, that which I call theInsertmentis fram’d thereof.
These Osculations are so made, that the Pores of theLignous Body, I think, notwithstanding, seldom run one into another; but, for the most part, still keep distinct; in the same manner as some of the Nerves, though they meet, and for some space are associated together, yet ’tis most probable that none of their Fibres are truly inosculated here, but only in the Plexures.
These Osculations of theLignous Body, and so the interception of the Insertions of theCortical, are not to be observ’d by the traverse cut of theRoot, but by taking off theBarque, or theCortical Body. In the Roots of Trees, they are generally obscure; but in Plants, often more distinctly apparent;and especially in aTurnep: the appearance whereof, theCortical Bodybeing stripp’d off, is as a piece of close-wrought Network, fill’d up with the Insertions of the saidCortical Body.SeeFig. 8.
The next and last distinct Part of theRootis thePith. The substantial nature thereof, is, as was said of theInsertment, the same likewise with that of theParenchymaof the Seed. And according to the best observation we have yet made, ’tis sometimes existent in itsRadicle; in which, the two main Branches of the Lobes both meeting, and being osculated together, are thus dispos’d into one round Trunk, and so environing part of theParenchyma, make thereof aPith; as in either theRadicle, or the youngRootof the greatBeanorLupine, may, I think, be well seen.
But many times the Originalhereof is immediately from theCortical Body. For in dissection of diversRootsboth of Trees and Plants, as ofBarberryorMallows, it is observable, that theCortical BodyandPithare both of them participant of the same Colour; in theBarberryboth of them tinged yellow, and inMallowsgreen. In cutting the smaller Parts of the Roots of many Plants, as ofBorage,Mallows,Parsley,Columbine, &c. ’tis also evident, that theLignous Bodyis not there in the least Concave, but standeth perfectly in the Center; and that the Insertions being gradually multiplied afterwards, thePithat length, towards the thicker parts of theRoot, shews and enlarges it self. Whence it appears, that in all suchRoots, thePithis not only of the same substantial nature, and by the Insertions doth communicate with theCortical Body; and thatit is also more or less augmented by it; which is true of thePithof allRoots; but is moreover, by mediation of the said Insertions, wholly originated from it. The various appearances of theInsertionsandPithfrom the Fibrous Parts to the top of theRoot,see inFig. 9,10,11,12,13,14. The Pores of theLignous Body, entire in the said Fibrous Parts, are best seen when they have lain by a night dry, after cutting.
A farther evidence hereof are the Proportions betwixt theCortical BodyandPith. For as about the inferiour Parts of theRoot, where thePithis small, theCortical Bodyis proportionably great; so about the top, where thePithis enlarged, theCortical Bodygroweth proportionably less,sc.because by its Insertions, ’tis gradually bestowed into thePith. Likewise the peculiar frame of someRoots, wherein besides thePith, theLignous Bodybeing divided into a double Ring, there is also a thick Ring, of a white and soft substance, stands betwixt them; and is nothing else but the Insertions of theCortical Bodycollected into the said Ring; but, towards the top of the Root, being inserted again, thus maketh a large and amplePith; as inFennel-Roots is seen.
The Pores of thePith, as those of theCortical Body, are extended both by the breadth and length of theRoot, much alike; yet are they more or less of a greater size than those of theCortical Body.
The Proportions of thePith, are various; in Trees, but small; in Plants generally, very fair; in some making by far the greatest part of theRoot; as in aTurnep: By reason of the wide circumference whereof, and so the finerConcoction and Assimilation of its Sap; that part which in most old Trunks is a dry and harshPith, here proves a tender pleasant meat. The parts of aTurnepin the travers cutsee inFig. 8.
In the Roots of very many Plants, asTurneps,Carrots, &c. theLignous Body, besides its main utmost Ring, hath divers of its osculated Fibres dispersed throughout the Body of thePith; sometimes all alike, and sometimes more especially in, or near, its Center; which Fibres, as they run towards the top of theRoot, still declining the Center, at last collaterally strike into its Circumference; either all of them, or some few, keeping the Center still; of these principally theLignous Bodyof the Trunk is often originated.
These Fibres, although they are so exceeding slender, yet in someRoots, as in that ofFlower-de-liz, they are visibly concave, each of them, in their several Cavities also embosoming a very smallPith; the sight whereof, the Root being cut traverse, and laid in a Window for a day or two to dry, may without Glasses be obtained. And this is the general account of theRoot; the declaration of the manner of its growth, with the use and service of its several parts, we shall next endeavour.
We say then, that theRadiclebeing impregnate, and shot into the Moulds, the contiguous moisture, by theCortical Body, being a Body laxe and Spongy, is easily admitted: Yet not all indiscriminately, but that which is more adapt to pass through the surrounding Cuticle. Which transient Sap, though it thus becomes fine, yet is not simple; but a mixture of Particles, both in respect of thoseoriginally in the Root, and amongst themselves, somewhat heterogeneous. And being lodg’d in theCortical Bodymoderately laxe, and of a Circular form; the effect will be an easie Fermentation. TheSapfermenting, a separation of Parts will follow; some whereof will be impacted to the Circumference of theCortical Body, whence the Cuticle becomes a Skin; as we see in the growing of the Coats of Cheeses, of the Skin over divers Liquors, and the like. Whereupon theSappassing into theCortical Body, through this, as through aManica Hippocratis, is still more finely filtred. With whichSap, theCortical Bodybeing dilated as far as itsTone, without a solution of Continuity will bear; and the supply of theSapstill renew’d; and the purest part, as most apt and ready, recedes, with its due Tinctures, from the saidCortical Body, to theLignous. WhichLignous Bodylikewise super-inducing its own proper Tinctures into the saidSap; ’tis now to its highest preparation wrought up, and becomes (as they speak of that of an Animal) the VegetativeRosorCambium: the noblest part whereof is at last coagulated in, and assimilated to the like substance with the saidLignous Body. The remainder, though not united to it, yet tinctur’d therein, thus retreats, that is, by the continual appulse of theSap, is in part carried off into theCortical Bodyback again, theSapwhereof it now tinctures into good Aliment: So that whereas before theCortical Bodywas only relaxed in its Parts, and so dilated; ’tis now increas’d in real quantity or number of parts, and so is truly nourish’d. And theCortical Bodybeing saturate with so much of this VitalSapas servesit self; and the second Remainders discharged thence to the Skin; this also is nourish’d and augmented therewith. So that as in anAnimal Bodythere is no instauration or growth of Parts made by the Bloud only, but theNervous Liquoris also thereunto assistant; so is it here: theSapprepared in theCortical Body, is as the Arterious; and that part thereof prepared by theLignous, is as theNervous Liquor; which partly becoming Nutriment to it self, and partly being discharged back into theCortical Body, and diffusing its Tincture through theSapthere, that to the saidCortical BodyandSkin, becomes also true Nutriment, and so they all now grow.
In which growth, a proportion in length and breadth is requisite: which being rated by the benefit of the Plant, both for firm standing and sufficient Sap, must thereforeprincipally be in length. And because it is thus requisite, therefore by the constitution of one of its Parts,sc.theLignous Body, it is also made necessary. For the Pores hereof, in that they are all extended by its length, theSapalso according to the frame and site of the said Pores will principally move; and that way as itsSapmoves, the same way will the generation of its Parts also proceed;sc.by its length. And theLignous Bodyfirst (that is, by a priority causal) moving in length it self; theCorticalalso moves therewith. For that which is nourish’d, is extended; but whatever is extended, is mov’d; that therefore which is nourish’d, is mov’d: TheLignous Bodythen being first nourish’d, ’tis likewise first mov’d, and so becomes and carries in it the Principle of all Vegetative motionin theCortical; and so they both move in length.
Yet as theLignous Bodyis the Principle of Motion in theCortical; so theCorticalis the Moderator of that in theLignous: As in Animal Motions, the Principle is from the Nerves; yet being once given to the Muscle or Limb, and that moving proportionably to its structure, the Nerves also are carried in the same motion with it. We suppose therefore, that as the principal motion of theLignous Bodyis in length, so is its proper tendency also to ascend: But being much exceeded both in Compass and Quantity by theCorticalas in the smaller parts of theRootit is; it must needs therefore be over-born and governed by it; and so, though not lose its motion, yet make it that way wherein theCortical Bodymay be more obedient to it; which will be by descent:Yet both of them being sufficiently pliable, they are thus capable, where the Soyl I may oppose a direct descent, there to divert any way where it is more penetrable, and so to descend obliquely. For the same reason it may also be, that though you set aBeanwith theRadicleupward; yet theRadicle, as it shoots, declining also gradually, is thus arch’d in form of an Hook, and so at last descends. For every declination from a perpendicular Line, is a mixed motion betwixt Ascent and Descent; as that of theRadiclealso is, and so seeming to be dependent upon the two contrary Tendencies of theLignousandCortical Bodies. What may be the cause of those Tendencies (being most probably external, and perhaps something of aMagnetisme) is besides my Task here to enquire.
Now although theLignous Body,by the position and shape of its Pores, principally groweth in length; yet will it in some degree likewise in breadth: For it cannot be supposed that the purestSapis all received into the said Pores; but that part thereof likewise, staying about itsSuperficial parts, is there tinctur’d and agglutinated to them. And because these Pores are prolonged by its length; therefore is it much more laxe and easily divisible that way; as in slitting a Stick, or cleaving of Timber, and in cutting and hewing them athwart is also seen. Whence it comes to pass, that in shooting from the Center towards the Circumference, and there finding more room, its said original Laxity doth easily in divers places now become greater, and at length in open Partments plainly visible. Betwixt which Partments, thecortical Body, being bound in on the onehand, by the surrounding Skin and Moulds, and pressed upon by theLignouson the other, must needs insert it self, and so move contrary to it, from the Circumference towards the Center: where the said contrary motions continued as begun, they at last meet, unite, and either make or augment thePith. And thus theRootis fram’d, and the Skin, thecorticalandLignous Bodies, so as is said, hereunto concurrent. We shall next shew the use of the two other Parts,sc. theInsertmentandPith; and first of thePith.
One true use of thePithis for the better Advancement of theSap, whereof we shall speak inthe next Chapter. The use we here observe is for the quicker and higher Fermentation of theSap: For although the Fermentation made in theCortical Bodywas wellsubservient to the first Vegetations, yet those more perfect ones in theTrunkwhich after follow, require a Body more adapted to it, and that is thePith; which is so necessary, as not to be only common to, but considerably large in theRootsof most Plants; if not in their inferiour parts, yet at their tops. Where though either deriv’d or amplify’d from theCortical Body, yet being by its Insertions only, we may therefore suppose, as those, so this, to be more finely constituted. And being also from its co-arctation, while inserted, now free; all its Pores, upon the supply of theSap, will more or less be amplified: Upon which accounts, theSapthereinto received, will be more pure, and its fermentation therein more active. And as thePithis superiour to theCortical Bodyby its Constitution, so by its Place. For as it thus stands central,it hath theLignous Bodysurrounding it. Now as the Skin is the Fence of theCortical Body, and that of theLignous; so is theLignousagain a far more preheminent one unto thePith; theSapbeing here a brisk Liquor, tunn’d up as in a wooden Cask.
And as thePithsubserves the higher Fermentation of theSap; so do the Insertions its purer Distribution; that separation which the parts of theSap, by being fermented in thePith, were dispos’d for; being, upon its entrance into the Insertions, now made: So that as the Skin is a Filtre to theCortical Body, so are the Insertions a more preheminent one to theLignous; and as they subserve the purer, so the freer and sufficient distribution of theSap: For theRootenlarging, and so theLignous Bodygrowing thicker, although theCorticaland thePithmight supplySapsufficient to the nutrition of its Parts next adjacent to them; yet those more inward, must needs be scanted of theirAliment; and so, if not quite starv’d, yet be uncapable of equal growth: Whereas theLignous Bodybeing through its whole breadth frequently disparted, and theCortical Bodyinserted through it; theSapby those Insertions, as the Blood by the disseminations of theArteries, is freely and sufficiently convey’d to its intimate Parts, even those which from either thecortical Bodyor thePithare most remote. Lastly, as the consequent hereof, they are thus assistant to the Latitudinal growth of theRoot; as theLignous Bodyto its growth in length; so these Insertions of theCortical, to its better growth in breadth.
Having thus seen the solitary uses of the Several Parts of theRoot, we shall lastly propound ourConjectures of that Design whereto they are all together concurrent, and that is the Circulation of theSap: For theSapmoving through thecortical Body, towards thePith, through the Insertions thereinto, obtains a pass: Which passage, the superiour Insertions will not favour; because thePithstanding in the same height with them, is there large, the fermenting and course of theSapquick, and so its opposition strong. But through the inferiour it will much more easily enter; because there, through the smalness of thePith, the opposition is little, and through the shortness of the Insertions, the way more open. So that though theSapmay meet with some opposition even here, yet here meeting with the least, here it will bestow it self (feeding theLignous Bodyin its passage) into thePith. Into which freshSapstill entring, this,yet but crude, will subside: that first received and so become a Liquor higher wrought, will more easily mount upwards; and moving in thePith, as in theArteria magna, in equal altitude with the more superiour Insertions; the most volatile parts of all will still continue their direct ascent towards theTrunk. But those of a middle nature, and, as not apt to ascend, so being lighter than those beneath them, not to descend neither; they will tend from thePithtowards the Insertions in a motion betwixt both; through which Insertions (feeding theLignous Bodyin its passage) it is, by the next subsequentSap, discharged off into thecortical Body, as into theVena cava, back again. Wherein, being still pursu’d by freshSapfrom the Center, and more occurring from the Circumference, towards the inferiour Insertionsit thus descends; through which, together with part of theSapafresh imbib’d from the Mould, it re-enters thePith. From whence, into theCortical Body, and from thence into thePith, the cruder part thereof reciprocally is disburs’d; while the most Volatile, not needing the help of a Circulation, more directly ascendeth towards theTrunk.
Having thus declar’d the degrees ofVegetationin theRoot; the continuance hereof in theTrunkshall next be shew’d: in order to which, the Parts whereof this likewise is compounded, we shall first observe.
That which without dissection shews it self, is theCoarcture: I cannot say of theRoot, nor of theTrunk; but what I chuse here to mention, as standing betwixt them, and so being common to them both; all their Parts being here bound in closer together, asin the tops of the grown Roots of very many Plants, is apparent.
Of the Parts of theTrunk, the first occurring is itsSkin: The Formation whereof, is not from the Air, but in theSeed, from whence it is originated; being the production of the Cuticle, there investing the twoLobesandPlume.
The next Part is theCortical Body; which here in theTrunkis no new substantial formation; but, as is that of theRoot, originated from theParenchymaof theSeed; and is only the increase and augmentation thereof. TheSkin, thisCortical Bodyproperly so call’d, and (for the most part) some Fibers of theLignousmixed herewith, all together make theBarque.
Next, theLignousBody, which, whether it be visibly divided into many softer Fibres, as inFennel, and most Plants; or that its partsstand more compact and close, shewing one hard, firm and solid piece, as in Trees; it is in all one and the same Body; and that not formed originally in theTrunk, but in theSeed; being nothing else but the prolongation of theInner Bodydistributed in theLobesandPlumethereof.
Lastly, TheInsertionsandPithare here originated likewise from thePlume, as the same in theRootfrom theRadicle: So that as to their substantial Parts, theLobesof the Seed, theRadicleandPlume, theRootandTrunkare all one.
Yet some things are more fairly observable in theTrunk. First, theLatitudinalshootings of theLignous Body, which inTrunksof several years growth, are visible in so many Rings, as is commonly known: For several young Fibres of theLignous Body, as in theRoot, so here, shooting into theCorticalone year, and the spaces betwixt them being after fill’d up with more (I think not till) the next, at length they become altogether a firm compact Ring; the perfection of one Ring, and the ground-work of another being thus made concomitantly.
From these Annual younger Fibres it is, that although theCortical BodyandPithare both of the same substantial nature, and their Pores little different; yet whereas thePith, which the first year is green, and of all the Parts the fullest ofSap, becomes afterwards white and dry; theCortical Body, on the contrary, so long as the Tree grows, ever keepeth green and moist,sc.because the said Fibers annually shoot into, and so communicate with it.
The Pores likewise of theLignous Body, many of them in well-grown Timber, as in Oaken boards,are very conspicuous, in cutting both lengthwise and traverse; they very seldom run one into another, but keep, like so many several Vessels, all along distinct; as by cutting, and so following any one of them as far as you please, for a Foot or half a Yard, or more together, may be observ’d.
These greater Pores, though in Wainscot, Tables, and the like, where they have lain long open, they are but meer Vacuities, and so would be thought to contain onlySapin the Tree, and afterwards only Air; yet upon a fresh cut, each of them may be seen fill’d up with a light and spongie Body, which by Glasses, and even by the bare eye, appears to be a perfectPith; sometimes entire, and sometimes more or less broken.
Besides these, there are a lesser sort; which, by the help of aMicroscope, also appear, if not to befill’d up with aPith, yet to contain certain light and filmy parts, more or fewer, of aPithynature within them.
And these are all the Pores the best Glasses, which, (when upon these Enquiries) we had at hand, would shew us. But the Learned and most Ingenious Naturalist Mr.Hooksheweth us moreover, besides these, a third, and yet smaller sort; the description whereof I find he hath given us amongst hisMicroscopical Observations. Of these Pores (as a confirmation of what, inthe Second Chapter, I have said of the Pores of theLignous Bodyin general) he also demonstrates; that they are all continuous and prolonged by the length of theTrunk; as are the greater ones; the Experiment whereof he imparteth to be, by filling up, suppose in a piece ofChar-coal, all the said Pores withMercury; which appears to pass quite through them, in that by a very good Glass it is visible in their Orifices at both ends; and without a Glass, by the weight of the Coal alone, is also manifest.
Upon farther Enquiry, I likewise find, that the Pores of theLignous Bodyin theTrunkof Plants, which at first only supposed, by the help of good Glasses are very fairly visible; each Fibre being perforated by 30, 50, 100, or hundreds of Pores. Or what I think is the truest notion of them, that each Fibre, though it seem to the bare eye to be but one, yet is indeed a great number of Fibres together; every Pore being not meerly a space betwixt the several pores of the Wood, but the Concave of a Fiber: So that if it be asked, what all that part of a Vegetable, either Plant or Tree, which is properly call’d the woodypart; what all that is, I suppose, that is nothing else but a Cluster of innumerable and most extraordinary small Vessels or concave Fibres.SeeFig. 15.
Next the Insertions of theCortical Body, which in theTrunkof a Tree saw’d athwart, are plainly discerned as they run from the Circumference toward the Center; the whole Body of the Tree being visibly compounded of two distinct Substances, that of the several Rings, and that of the Insertions, running cross; shewing that in some resemblance in a Plain, which the Lines of Latitude and of the Meridian do in a Globe.SeeFig. 16.
These Insertions are likewise very conspicuous in Sawing of Trees length-wayes into Boards, and those plain’d, and wrought into Leaves for Tables, Wainscot, Trenchers, and the like. In allwhich, as in course Trenchers made ofBeech, and Tables of Oak, there are many parts which have a greater smoothness than the rest; and are so many inserted pieces of theCortical Body; which by reason of those of theLignous, seem to be discontinuous; although in theTrunkthey are extended throughout its Breadth.
These Insertions, although as is said, of a quite distinct substance from theLignous Body, and so no where truly incorporated with it, yet being they are in all parts, the one as the Warp, the other as the Woof, mutually braced and inter-woven together, they thus constitute one strong and firmly coherent Body.
As the Pores are greater or less, so are the Insertions also: To the bare eye usually the greater only are discernable: But through an indifferentMicroscopethere areothers also, much more both numerous and small, distinctly apparent. So that, I think, we may observe, that as the grandPithof theTrunkcommunicates with, and is augmented by the greater Insertions; so is thePithof each greater Pore originated from the less; and those (at least) pithy parts in the Midling Pores, from others still less; and suppose, that the least of all are so far intruded into the smallest Pores, as only just to cause a kind of roughness on their concave sides, and no more; to what end shall be said.SeeFig. 17.
In none of all these Pores can we observe any thing which may have the true nature and use of Valves, which is easily to admit that, to which they will by no means allow a regress. And their non-existence is enough evident, from what inthe first Chapterwe have said of theLobesof theSeed:in whoseSeminal Root, were there anyValves, it could not be, that by a contrary course of theSap, they should ever grow; which yet, where-ever they turn into Dissimilar Leaves, they do. Or if we consider the growth of theRoot, which oftentimes is upward and downward both at once.
The Insertions here in theTrunkgive us likewise a sight of the position of their Pores. For in a plained piece of Oak, as in Wainscot, Tables,&c.besides the larger Pores of theLignous Body, which run by the length of theTrunk; the Tract likewise of those of the Insertions may be observed to be made by the breadth, and so directly cross. Nor are they continuous as those of theLignous Body, but very short, as those both of theCortical BodyandPith, with which the Insertions, as to their substance are congenerous. Yetthey all stand so together, as to be plainly ranked in even Lines or Rows throughout the breadth of theTrunk: As the Tract of these Pores appear to the naked Eye,see inFig. 18. By the best Microscope I have at hand, I can only observe the Ranks of the Pores; not the Pores themselves, saving here and there one; wherefore I have not describ’d them.
The Pores of thePithlikewise being larger here in theTrunk, are better observable than in theRoot: the width whereof, in comparison with their sides so exquisitely thin, may by an Honey-Comb be grosly exemplified; and is that also which the vast disproportion betwixt the Bulk and weight of a dryPithdoth enough declare. In theTrunksof some Plants, they are so ample and transparent, that in cutting both by the length and breadth of thePith, some of them, even tothe bare eye would seem to be considerably extended by the length of the saidPith; which once I also thought they were, and that only the rest of them were but short and discontinuous, and as ’tis said, somewhat answerable to the Cells of an Honey-Comb. This was the nearest we could come to them, by conjecture, and the assistance of the best Glasses we then had by us, when upon enquiry into the nature of thePith:But that Worthy Person newly mentioned Mr.Hookesheweth us, that the Pores of thePith, particularly ofElder-Pith, so far as they are visible, are all alike discontinuous; and that thePithis nothing else (to use his own words) but an heap of Bubbles.
Besides what this Observation informs us of here, it farther confirms what inthe second Chapterwe have said of the Original of thePithandCortical Body, and of the sameness of both their natures with theParenchymaof the Seed. For, upon farther enquiry with better Glasses, I find, that theParenchymaof thePlumeandRadicle, and even of theLobesthemselves, though not so apparently, is nothing else but a Mass of Bubbles.
In thePithsof many Plants, the greater Pores have some of them lesser ones within them, and some of them are divided with cross Membranes: And betwixt their several sides, have, I think, other smaller Pores visibly interjected. However, that they are all permeable, is most certain. They stand together not indeterminately, but in even Ranks or Trains; as those of the Insertions by the breadth, so these by the length of theTrunk. And thus far there is a general corresponding betwixt the part of theRootandTrunk: Yet are theresome considerable Disparities betwixt them; wherein, and how they come to pass, and to what especial use and end, shall next be said.
We say then, that theSapbeing in theRootby Filtrations, Fermentations (and in whatRootsneedful, perhaps by Circulation also) duly prepar’d; the prime part thereof passing through the intermediate Coarcture, in due moderation and purity is entertain’d at last into theTrunk. And theSapof theTrunkbeing purer and more volatile, and so it self apt to ascend; the motion of theTrunklikewise will be more noble, receiving a disposition and tendency to ascend therewith. And what by theSaptheTrunkis in part dispos’d to, by the respective position and quantity of its Parts it is effectually enabled. For whereas in theRoottheLignousBodybeing in proportion with theCortical, but little, and all lying close within its Center; it must therefore needs be under its controul: on the contrary, being here comparatively of greater quantity, and also more dilated, and having divers of its Branches standing more abroad towards the Circumference, as both in the Leaves and Body of the youngTrunkandPlume, is seen; it will in its own tendency to ascend, reduce theCortical Bodyto a compliance with it.
And theTrunkthus standing from under the restraint of the Mould in the open Air, the disposition of its Parts originally different from that of the Parts in the Root will not only be continued, but improved: For by the force and pressure of theSapin its collateral Motion, theLignous Bodywill now more freely and fartherbe dilated. And this being dilated, theCortical Bodyalso, must needs be inserted; and is therefore in proportion alwayes more or less smaller here in theTrunk, than in theRoot. And as theCortical Bodylessens, so thePithwill be enlarged, and by the same proportion is here greater. And thePithbeing enlarged it self, its Pores (theLignous Body, upon its dilatation, as it were tentering and stretching out all their sides) must needs likewise be enlarged with it, and accordingly are ever greater in thePithof theTrunk, than of theRoot. And the dilatation of theLignous Bodystill continued, it follows, that whereas thePithdescendent in theRoot, is not only in proportion less and less, but also in the smaller extremities thereof, and sometimes higher altogether absent: Contrariwise, in theTrunkit is not onlycontinued to its top, but also there in proportion equally ample with what it is in any other inferiour part.
But although the openness of the Ayr permitting be alwayes alike; yet the Energy of theSapeffecting; being different; as therefore that doth, the dilatation of theTrunkwill also vary. If that be less, so is this; as in theTrunksof most Trees: If that be greater, so is this; as in Plants is common; theLignous Bodybeing usually so far dilated, that theutmost shootingsthereof may easily be seen to jut out, and adjoyn to the Skin. And if theSapbe still of greater energy, it so far dilates theLignous Body, as not only to amplifie thePithand all its Pores; but also so far to stretch them out, as to make them tear. Whereupon either running again into theCortical Body, or shrinking up towardsit, theTrunkthus sometimes becomes anhollow Stalk, thePithbeing wholly, or in part voyded. But generally it keeps entire; and where it doth, the same proportion and respect to theLignousandCortical Bodies, as is said. The Consequences of all which will be, the strength of theTrunk, the security and plenty of theSap, its Fermentation will be quicker, its Distribution more effectual, and its Advancement more sufficient.
First, the erect growth and strength of theTrunk; this being by the position of its several parts effected: For besides the slendering of theTrunkstill towards the top, the Circumferential position of theLignous Bodylikewise is, and that eminently hereunto subservient: So that as theLignous Bodyin the smaller part of theRootstanding Central, we may thenceconceive and see their pliableness to any oblique motion; so here, on the contrary, theLignous Bodystanding wide, it thus becomes the strength of theTrunk, and most advantageous to its perpendicular growth. We see the same Design inBonesandFeathers: The strongestBones, as those in the Legs, are hollow. Now should we suppose the sameBoneto be contracted into a Solid Body, although now it would be no heavier, and in that respect, as apt for motion; yet would it have far less strength, than as it is dilated to a Circumferential posture. And so forQuills, which, for the same Reasons, in subserviency to flight, we see how exceeding light they are, and yet, in comparison with the thinness of their Body, how very strong: We see it not only in Nature, but Art. For hence it is thatJoynersandCarpentersunite and set together their Timber-pieces and several Works oftentimes with double Joynts; which, although they are no thicker than a single one might be made, yet standing at a distance, have a greater strength than that could have. And the same Architecture will have the same use in theTrunksof Plants, in most whereof ’tis very apparent; as for instance, in Corn: For Nature designing itsSapa great Ascent for its higher maturity, hath given it a tallTrunk; but to prevent its ravenous despoiling either of the Ear or Soyl; although it be tall, yet are its sides but thin: and because again, it should grow not only tall and thriftily, but for avoiding propping up, strongly too; therefore, as its height is over-proportioned to the thinness of its sides, so is its Circumference also; being so far dilated as to parallel aQuillit self. Besides the position of theLignous Bodywithin the compass of a Ring, we see some shootings thereof often standing beyond the Circumference of the said Ring, making sometimes a triangular, oftner a quadrangular Body of theTrunk; to the end, that the Ring being but thin, and not self-sufficient, these, like Splinters toBones, might add strength and stability to it.
Next, the security and plenty of theSap. For should theLignous Body, as it doth in theRoot, its smaller parts, stand Central here also, and so theCorticalwholly surround it: the greater part of theSapwould thus be more immediately expos’d to the Sun and ayr; and being lodg’d in a laxe Body, by them continually be prey’d upon, and as fast as supplied to theTrunk, be exhausted. Whereas thePithstanding in theCenter, theSaptherein being not only most remote from the Ayr and Sun, but by theBarque, and especially theWood, being also surrounded and doubly immur’d, will very securely and copiously be conveyed to all the Collateral parts, and (as shall be said how) the top of theTrunk.
And theSapby the amplitude, and great porosity of thePithbeing herein more copious, its Fermentation also will be quicker; which we see in all Liquors by standing in a greater quantity together, proceeds more kindly: And being tunn’d up within theWood, is at the same time not only secur’d from loss, but all extream mutations, the Day being thus not too hot, nor the Night too cold for it.
And the Fermentation hereof being quicker, its motion also will be stronger, and its distributionmore effectual, not only to the dilatation of theTrunk, but likewise the shooting out of the Branches. Whence it is, that in the Bodies of Trees, theBarqueof it self, though it be sappy, and many Fibres of theLignous Bodymixed with it, yet seldom sendeth forth any; and that in Plants, those with the leastPith(other advantages not supplying this defect) have the fewest or smallest Branches, or other collateral Growths: and thatCorn, which hath noPith, hath neither any Branches.
Lastly, the Advancement of theSapwill hence also be more ready and sufficient. For the understanding where, and how, we suppose that in allTrunkswhatsoever there are two parts joyntly hereunto subservient. In some theLignous Bodyand theCortical, as in olderTrunks, thePithbeing eitherexcluded or dried: But in most, principally theLignous BodyandPith; as in most Annual Growths of Trees; but especially Plants, where theCortical Bodyis usually much and often wholly inserted.
Of theLignousbody it is so apparent by its Pores, or rather by its Vessels, that we need no farther evidence. For to what end are Vessels but for the conveyance of Liquor? And is that also, which upon cutting the young Branch of a Sappy Tree or Plant, by an accurate and steady view may be observed. But when I say the Pores of theLignous Body, I mean principally them of the younger shootings, both those which make the new Ring, and those which are mixed with theCortical Bodyin theBarque: that which ascendeth by the Pores of the older Wood, being probably, because in lessquantity, more in form of a Vapour, than a Liquor. Yet that which drenching into the sides of its Pores, is with all thereunto sufficient Aliment; as we seeOrpine,Onions, &c. only standing in a moyster Ayr will often grow; And being likewise in part supplied by the Insertions from the younger Shoots: But especially, because as it is but little, so it serveth only for the growth of the saidOlder Wood, and no more; whereas the more copious Aliment ascendent by the younger Shoots, subserves not only their own growth, but the generation of others; and is besides with that in theCortical Bodythe Fountain ofPerspirations, which we know even in Animals are much more abundant than theNutritive parts; and doubtless in aVegetableare still much more.
But these Pores, although they are a free and open way to theascendingSap; yet that meer Pores or Vessels should be able of themselves to advance theSapwith that speed, strength & plenty, and to that height, as is necessary, cannot probably be supposed. It follows then, that herein we must grant thePitha joynt service. And why else in the smaller parts of theRoot, where thePithis often wanting, are the Pores there greater? Why is thePithin all primitive growths the mostSappypart, why hath it so great a stock ofSap, if not after due maturation within it self still to be disbursed into the Fibres of theLignous Body? Why are the annual growths of all both Plants and Trees with great Piths, the quickest and the longest? But how are the Pores of thePithpermeable? That they are so, both from their being capable of a repletion withSap, and of being again wholly emptied of it, andagain, instead thereof fill’d with Ayr, is as certain as that they are Pores. That they are permeable, by the breadth, appears from the dilatation of theLignous Body, and from the production of Branches, as hath been, and shall hereafter be said. And how else is there a Communion betwixt this and theCortical Body? That they are so also, by the length, is probable, because by the bestMicroscopewe cannot yet observ, that they are visibly more open by the breadth, than by the length. And withal are ranked by the length, as those of the Insertions by the breadth of theTrunk. But if you set a piece of dryElder-Pithin some tinged Liquor, why then doth it not penetrate the Pores, so as to ascend through the Body of thePith? The plain reason is, because they are all fill’d with Ayr. Whereas thePithin a Vegetating Plant, as its Partsor Pores are still generated, they are at the same time also fill’d withSap; which, as ’tis gradually spent, is still repair’d by more succeeding, and so the Ayr still kept out; as in all primitive growths, and thePithofElderit self: Yet the samePith, by reason of the following Winter, wanting a more copious and quick supply ofSap, thus once become, ever after keeps dry. And since in the aforesaid Trial the Liquor only ascends by the sides of thePith, that is of its broken Pores, we should thence by the same reason conclude that they are not penetrable by the breadth neither, and so no way; and then it need not be ask’d what would follow. But certainly theSapin the Pores of thePithis discharged and repaired every moment, as by its shriv’ling up; upon cutting the Plant is evident.
We suppose then, that as theSapascendeth into theTrunkby theLignous Body, so partly also by thePith. For a piece ofCottonwith one end immers’d in some tinged Liquor, and with the other erect above, though it will not imbibe the Liquor so far as to over-run at the top, yet so as to advance towards it, it will; so here, thePithbeing a porous and spongy Body, and in its Vegetating state its Pores also permeable, as a curious Filtre of Natures own contrivance, it thus advanceth, or as people use to say, sucks up theSap. Yet as it is seen of the Liquor in the Cotton; so likewise are we to suppose it of theSapin thePith; that though it riseth up for some way, yet is their some term, beyond which it riseth not, and towards which the motion of the ascendingSapis more and more broken, weak and slow, and so the quantity thereof less and less. But becausetheSapmoveth not only by the length, but breadth of thePith; at the same time therefore as it partly ascendeth by thePith, it is likewise in part pressed into theLignous Bodyor into its Pores. And since the motion of theSapby the breadth of thePithnot being far continued, and but collateral, is more prone and easie than the perpendicular, or by its length; it therefore follows, that the collateral motion of theSap, at such a height or part of thePith, will be equally strong with the perpendicular at another part, though somewhat beneath it; and that where the perpendicular is more broken and weak, the collateral will be less; and consequently where the perpendicular tendency of theSaphath its term, the collateral tendency thereof, and so its pressure into the Pores of theLignous Bodywill still continue.Through which, in that they are small, and so their sides almost contiguous, theSapas fast as pressed into them will easily run up; as betwixt the two halves of a Stick first slit, and then tied somewhat loosely together, may also any Liquor be observed to do. And the sides of the said Pores being not smooth, but by the intrusion of the smallest insertions made somewhat rough; by that means the higher and more facile ascent of theSaptherein will farther be promoted. By all which Advantages the facility and strength of that ascent will be continued higher in the said Pores than in thePith. Yet since this also, as well as that in thePithwill have its term; theSap, although got thus far, would yet at last be stagnant, or at least its ascent be very sparing, slow and feeble, if not some way or other re-inforced. Wherefore, as theSapmoving by the breadth of thePith, presseth thence into the Pores of theLignous Body; so having well fill’d these, is in part by the same Collateral motion disbursed back into a yet higher Region of thePith. By which partly, and partly by that portion of theSap, which in its perpendicular ascent was before lodged therein; ’tis thus here, as in any inferiour place equally repleat. Whereupon the force and vigour of the perpendicular motion of theSapherein will likewise be renew’d; and so its Collateral motion also, and so its pressure into the Pores of theLignous Body, and consequently its ascent therein; and so by a pressure from these into thePith, and from thePithinto these reciprocally carried on, a most ready and copious ascent of theSapwill be continued from the bottom to the top, though of the highestTrunk.
The distinct Parts whereof these are constituted, are the same with those of theTrunk, and but the continuation of them.
Trunk-Rootsare of two kinds: Of the one, are those that vegetate by a direct descent: The place of their Eruption is sometimes all along theTrunk; as inMint, &c. Sometimes only at its utmost point, as in theBramble.
The other sort are such as neither ascend nor descend, but shootforth at right Angles with theTrunk; which therefore, though as to their Office, they are trueRoots, yet as to their Nature, they areaMiddle thingbetwixt aRootand aTrunk.
Claspers, though they are but of one kind, yet their nature is double; not a mean betwixt that of theRootand that of theTrunk, but a compound of both; as in their Circumvolutions, wherein they often mutually ascend and descend, is seen.
The use of these Parts may be observed as theTrunkmounts, or as it trails. In the mounting of theTrunk, they are for support and supply: For support, we see theClaspersofVines; the Branches whereof being very long, fragile and slender, unless by theirClaspersthey were mutually contain’d together, they must needs by their own weight, and that oftheir Fruit, undecently fall, and be also liable to frequent breaking. So that the whole care is divided betwixt the Gardener and Nature; the Gardener with his Ligaments of Leather secures the main Branches; and Nature with these of her own finding, secures the less. Their Conveniency to which end, is seen in their Circumvolutions, a motion not proper to any other Part: As also in their toughness or strength, though much more slender than the Branches whereon they are appendent.
For Supply, we see theTrunk-RootsofIvy: For mounting very high, and being of a closer Constitution than that of aVine, theSapcould not be sufficiently supplied to the upper Sprouts, unless these to theMother-Rootwere joyntly assistant. Yet serve they for support likewise; whence they shoot out, not as inCresses,Brook-lime,&c. reciprocally on each side, but commonly all in one; that so they may be fastened at the nearest hand.
In the Trailing of theTrunk, they serve for stabiliment, propagation and shade. For stabiliment, we see theClaspersofCucumbers: For theTrunkandBranchesbeing long and fragile, the Brushes of the Winds would injuriously hoise them to and fro, to the dammage both of themselves and their tender Fruit, were they not by these Ligaments brought to good Association and Settlement.
As for this end, so for Propagation, we see theTrunk-RootsofCamomile. Whence we have the reason of the common observation, that it grows better by being trod upon: the Mould, where too laxe, being thus made to lie more conveniently about the saidTrunk-Rootsnewly bedded therein; andis that which we see also effected in Rowling ofCorn.
For both these ends, we see theTrunk-RootsofStrawberries; as also for shade; for in that we see allStrawberriesdelight; and by the trailing of the Plant is well obtain’d: So that as we are wont to tangle the Twigs of Trees together to make anArbour Artificial; the same is here done to make aNatural one; as likewise by theClaspersofCucumbers: For the Branches of the one by the Linking of theirClaspers, and of the other by the Tethering of theirTrunk-Roots, being couched together; their tender fruits thus lie under the Umbrage of aBowermade of their own Leaves.
The Parts of theGermenandBranch, are the same with those of theTrunk; the sameSkin,CorticalandLignous Bodies,InsertmentandPith, hereinto propagated, and distinctly observable herein.
For upon Enquiry into the Original of aBranchorGermen, it appears, That it is not from theSuperficiesof theTrunk, but so deep, as to take with theCortical, theLignous Bodyinto it self; and that not only from its Circumference,but (so as to take thePithin also) from itsInnerorCentral parts. Divers whereof may commonly be seen to shoot out into thePith; from whichShootsthe surrounding and more superiourGermensare originated; in like manner as theLignous Bodyof theTrunkis sometimes principally from those FibrousShootswhich run along thePithin theRoot.
The manner wherein usually theGermenandBranchare fram’d, is briefly thus: TheSap(as is said,Chap. 3.) mounting in theTrunk, will not only by its length, but by its breadth also, through theInsertionspartly move. Yet, its Particles being not all alike qualified, in different degrees: Some are more gross and sluggish; of which we have the formation of a Circle of Wood only; or of an Annual Ring: Others are more brisk; and by these we have theGermenpropagated. For by the vigour of their own motion from the Center, they impress an equal tendency on some of the inner parts of theLignous Bodynext adjacent to thePith, to move with them. And since theLignous Bodyis not entire, but frequently disparted; through these dispartments, the said interiour Parts, upon their Nutrition, actually shoot; not only towards the Circumference, so as to make part of a Ring, but even beyond it, in order to the production of aGermen. And theLignous Bodythus moving, and carrying theCorticalalong with it; they both make a force upon theSkin: Yet their motion being most even and gradual, that force is such likewise; not to cause the least breach of its parts, but gently to carry it on with themselves; and so partly by the extension of its already existentparts, as of those of Gold in drawing of Guilded Wyer; and partly by the accretion of new ones, as in the enlarging of a Bubble above the Surface of the Water, it is extended with them to their utmost growth. In which growth, theGermenbeing prolonged, and so displaying its several parts, as when aProspectiveorTelescopeis drawn out, thus becomes aBranch.
The same way as the propagation of the Parts of aGermenis contriv’d is its due nutrition also: For being originated from the inner part of theLignous Body, ’tis nourished with the best fermentedSapin theTrunk,sc.that next adjacent to it in thePith. Besides, since all its Parts, upon their shooting forth, divaricate from their perpendicular, to a cross Line, as these and the other grow and thrive together, bind and throngeach other into a Knot; through which Knot theSapbeing strain’d, ’tis thus in due moderation & purity delivered up into the Branch.
And for Knots, they are so necessary, as to be seen not only where collateral Branches put forth; but in such Plants also as shoot up in one singleTrunk; as inCorn; wherein, as they make for the strength of theTrunk; so by so many percolations as they are Knots, for the transmission of theSapmore and more refined towards the Ear. So that the two general uses of Knots are for firmer standing, and finer growth.
Lastly, as the due Formation and Nutrition of theGermenare provided for, so is its security also; which both in its position upon theTrunk, and that of its Parts among themselves may be observed. The position of its Parts shall be considered in speaking of theLeaf. As to its standing in thetrunk, ’tis alwayes betwixt thetrunkorElder Branch, and theBasisof the Stalk of theLeaf; whereby it is not only guarded from the Injuries of any contingent Violence, but also from the more piercing assaults of the Cold, so long till in time ’tis grown, as larger, so more hardy. The manner and uses of the position of everyGermen, considered as after it becomes aBranch, hath already been by the Ingenious Mr.Sharrockvery well observed; to whom I refer.
Upon the prolongation of theGermeninto aBranch, itsLeavesare thus display’d. The Parts whereof are substantially the same with those of aBranch: For the Skin of the Leaf is only the ampliation of that of theBranch; being partly by the accretion of new, & partly the extention of its already existent parts (dilated as in makingofLeaf-Gold) into its present breadth. The Fibres or Nerves dispersed through the Leaf, are only the Ramifications of theBranch’s Wood, orLignous Body. TheParenchymaof the Leaf which lies betwixt the Nerves, and as in Gentlewomens Needle-works, fills all up, is nothing else but the continuations of theCortical Body, or inner part of theBarquefrom theBranchinto it self, as in most Plants with a fat Leaf, may easily be seen.
The Fibres of theLeafneither shoot out of theBranchnorTrunk, nor stand in theStalk, in an even Line; but alwayes in either an Angular or Circular posture, and usually making either a Triangle, or a Semi-Circle, or Cord of a Circle; as inCycory,Endive,Cabbage, &c. may be observed: And if the Leaf have but one main Nerve, that also is postur’d in a Circular or Lunar Figure;as inMintand others. The usual number of these Nerves or Fibres is 3, 5, or 7. See theFiguresfrom 20, to 29.
The reason of the said Positions of the Fibres in theStalkof theLeaf, is for its more erect growth, and greater strength; which, were the position of the said Fibres in an even Line, and so the Stalk it self, as well as the Leaf flat, must needs have been defective; as from what we have said of the Circumferential posture of theLignous Bodyin theTrunk, we may better conceive.
As likewise for the security of itsSap: For by this means it is, that the several Fibres, and especially the main or middle Fibre of the Leaf, together with a considerable part of theCortical Body, are so disposed of, as to jut out, not from its upper, but its back, or nether plain. Whence the wholeLeaf, reclining backward, becomes a Canopy to them, defending them from those Injuries which from colder Blasts, or an hotter Sun, they might otherwise sustain. So that by a mutual benefit, as these give suck to all the Leaf, so that again protection to these.
These Fibres are likewise the immediate visible Cause of the shape of the Leaf: For if the nethermost Fibre or Fibres in the Stalk be in proportion greater, the Leaf is long, as inEndive,Cycory, and others: If all of a more equal size, it spreads rounder, as inIvy,Doves-foot,Colts foot, &c. And although aDock-Leafbe very long, whose Fibres notwithstanding, as they stand higher in the Stalk, are disposed into a Circle all of an equal size; yet herein a peculiar fibre, standing in the Center betwixt the rest, and running through the length of the Leaf, may be observed.
In correspondence also to the size and shape of these Fibres, is the Leaf flat: In that either they are very small, or if larger, yet they never make an entire Circle or Ring; but either half of one, as inBorage, or at most three parts of one, as inMullen, may be seen. For if either they were so big, as to contain; or so entire, as perfectly to include aPith, the Energy of theSapin thatPith, would cause the saidLignous Ringto shoot forth on every side, as it doth in theRootorTrunk: But the said Fibres being not figur’d into an entire Ring, but so as to be open; on that hand therefore where open, they cannot shoot any thing directly from themselves, because there they have nothing to shoot; and theSaphaving also a free vent through the said opening, against that part therefore which is thereunto opposite, it can have no force;and so neither will they shoot forth on that hand; and so will they consequently that way only which the force of theSapdirects, which is only on the right and left.
The several Fibres in the Stalk, are all inosculated in the Leaf, with very many Sub-divisions; according as these Fibres are inosculated near, or at, or shoot directly to the edge of the Leaf, is it even or scallop’d. Where these Inosculations are not made, there we have noLeaves, but only a company ofRamulets, as inFennel.