The comparative anatomy of trunks together with an account of their vegetation grounded thereupon; in two parts: the former read before the Royal Society, Feb. 25. 1674/5; the latter, June 17. 1675. The whole explicated by several figures in nineteen copper-plates; presented to the Royal Society in the years 1673. and 1674. By Nehemiah Grew, M.D. and fellow of the Royal Society.

THE Comparative Anatomy OF TRUNKS.

CHAP. I.

TO the end we may know and clearly understand, what the Trunk, Stalk, or Branch of a Plant is; I shall, by these Figures here before us, describe the several Parts whereof it is compounded.

And, for examples sake, I shall in the first place, describe the Trunks of six seve∣ral kinds of Plants, as they appear to, and are observeable by the naked eye. Which having done, I shall next proceed to a more particular Description of divers o∣ther

Trunks and Branches as they appear through the Microscope I made use of. In both shewing, not only what their several Parts are, as belonging to a Branch; but also by a comparative prospect, in what respects they are specifically distinguished one from another, in the several species of Branches.

LET the First Trunk then to be descri∣bed, be that of Borage: in a slice where∣of cut transversly, appears, first a tough, yet fine and transparent Skin. Within this Skin there is also a slender Ring of Sap-Vessels: which, without being crushed in the least, do yield a Lympha.

Next standeth the Parenchyma of the Bark. Which is every where made up of a great number of very small Bubles or Ve∣sicles. Upon the inner Verge of this Paren∣chyma, standeth another Ring of Sap-Ves∣sels: which also yeild a Lympha; and that different, as is probable, from the Lympha in the utmost Ring. Hitherto goes the Bark.

Adjacent to the Ring of Sap-Vessels, on the inner Verge of the Bark; stand the Air-Vessels, on the outer Verge of the Pith. Not in a Ring; but in Several Parcels; some parcels in the figure of little specks; others in little arched lines, almost like an V

Consonant. And being viewed in a good Glass, there appears to be within the com∣pass of every larger speck, about 20 or 30 Air-vessels; and within the smallest about 8 or 10.

The Pith, in a well grown stalk, is al∣ways hollow. But originally it is entire. It is wholly made up of a great number of Vesiculae; being pentangular, sexangular, and septangular. And most of them larg∣er than those of the Bark; so as to be plainly visible to a naked eye.

LET the next be Taraxacum, or Dan∣delyon. In a slice whereof cut alike trans∣versly, is seen, first a skin, then a simple, white, and close Parenchyma; made up like∣wise of Vesiculae; but those exceeding small.

Within this white and thick parenchy∣mous Ring, stand the Milk-vessels, in seve∣ral distinct Columns, of different size; each Column being made up of 7. or 8. ar∣ched lines. Betwixt these Columns, run as many Diametral Portions, derived from the said white and thick Parenchyma, into or towards the Pith.

Next within these, stand the Air-vessels. Which are likewise divided, by the said Diametral Portions, into divers arched lines. The size of these Vessels, as well as their number is less than in Borage.

Within these stands the Pith, consisting of very small Bubles or Vesicles, as the Bark. 'Tis very small, the Diameter hereof, be∣ing scarce one fifth of that of the Pith of Borage. But the Bark of Borage is not half so thick as this of Dandelyon.

A THIRD Trunk, shall be that of Cole∣wort. Wherein cut in like manner as be∣fore, may be observed, first a skin. Next to which, a very close and darkish Paren∣chyma. Wherewith are mixed some few Sap-vessels, which give it that hew.

Within this stands a scalloped parenchy∣mous Ring, or a Ring of many short and slender white Arches. Which every where meeting together, run in so many white Diametral Portions into the Pith.

Next to the said white Arches, and be∣twixt the said Diametral portions stands as many small parcels of Sap-vessels, like so many little half-ovals. Within each of which, is included a white Parenchyma.

On the inner verge of the Bark stands a∣nother sort of Sap-vessels, in one slender and entire Ring. And so far goes the Bark.

Next within this Ring stand the Air-vessels, in several parcels, diametrically opposite to the said parenchymous parcels next without the Sap-Ring.

Last of all, and more within the Pith, stand the same kind of Sap-vessels, as those of the Half-ovals. Both these, by small lines, run one into another; thus on both sides, hemming in the Air-vessels, and so ma∣king altogether, so many little Pyramids.

LET a fourth be Holyoak. Wherein, be∣ing cut as before, next to the skin stands the Parenchyma, somewhat close; and, in proportion thick.

Towards the inner verge hereof, stand one sort of Sap-vessels, postur'd in short Rays. These Vessels yield a Mucilage. And on the inner verge of the Bark, stands a thin Ring of other Sap-vessels.

Next within the Bark stand the Air-vessels, postur'd likewise in short Rays, di∣ametrically opposite to those in the Bark. In every Ray, there are about 12. or 16. Vessels.

Lastly, and more within the Pith, there stand other Sap-vessels, all in very thin or slender Chords; thus hemming in the several parcels of Air-vessels.

For a fifth, I will take that of wild Cu∣cumer. Wherein first of all next to the skin, there is a Ring of Sap-vessels. Which Ring is also made up of rays, all poynting to, and most of them terminating on the skin.

Next of all there is a thick, and simple parenchymous Ring. On the inner verge whereof, there are other Sap-vessels standing in parcels, also in a Ring. So far goes the Bark.

Next within stand the Air-vessels, in as many parcels contiguous to those of the Sap-vessels aforesaid To which likewise are adj••••n••d as many more parcels of Sap∣vessel wi••••in the Pith, opposite to the said Sap-vessels within the Bark.

LET the sixth be the Trunk of Endive. In which, next to the skin, there is, first a thick and simple Parenchyma. Then there is a kind of undulated Ring of Milk-vessels. Within which stand a sort of Lymphaeducts, in several parcels, some in arched half-ovals, others in short slender rays. Betwixt these parcels, many of the Milk-vessels likewise stand.

Next there is an undulated Ring of other Lymphaeducts, parting, as in most Trunks, betwixt the Bark and the pith. Within which are the Air-vessels. And within these more Sap-vessels. Both of them in small specks, answerable, or opposite to the rays in the Bark.

All the parts of these six Trunks, may as I have now described them, be obser∣ved, without a Microscope: excepting only the number of the Air vessels. Yet three

things are necessary; viz. a good eye a clear sight, and a Rasor wherewith to cut.

CHAP. II.

I NOW proceed to a more particular De∣scription of several Trunks and Bran∣ches, as they appear through the best Mi∣croscopes.

Now the Trunk, or Branch of every Tree hath three general parts to be descri∣bed; sc. the Bark, the Wood, and the Pith. That likewise of every Herhaceous Vegetable, hath either the same three parts; or els three parts analogous; sc. the Cor∣tical, the Lignous, and the Pithy parts.

The Bark consisteth of two parts, sc. the outmost skin, and the main Body. The skin is generally composed of very small Vesicles or Bladders, cluster'd together. That is, originally; but as the Plant grows, the the skin dries, & the said Bladders do very much shrink up and disappear.

Amongst these Bladders of the skin, there are usually intermixed a sort of Lignous Fibers, or Vessels, which run through the length of the skin; as in Mallow, Nettle,

Borage, Thistle, and most Plants. Which is not only argued from the toughness of the skin by means of the said Vessels; but in some Plants may be plainly seen, as in Teas••le.

Whether they are Air-vessels, or Sap∣vessels, is dubious. For on the one hand, because they emitt no Sap, or bleed not, 'tis propable that they are Air-vessels. On the other hand, they may be Sap-vessels, notwithstanding. Because the non-emissi∣on of Sap is not an infallible and conclud∣ing argument of an Air-vessel.

For there are some Plants which bleed not. Which yet are furnished with Sap∣vessels, as certainly as any others which bleed.

The skin of the Trunk is sometimes visi∣bly porous. But no where more, than in the better sort of walking Canes; where the pores are so big, as to be visible even to the naked eye; like to those upon the ends of our fingers. See Fig. 7.

The main Body of the Bark consisteth likewise of two parts, sc. Parenchyma, and Vessels. The Parenchyma is made up of an innumerable company of small Bladders clu∣stered together. Differing in nothing from those aforesaid in the skin; saving that they are much larger; and generally roun∣der.

This Parenchyma of the Bark is the same as to its substance, both in the Root and Trunk. Yet as to the Texture of its parts, in the one, and in the other, there is this observeable difference, viz. That in the Bark of the Root cut transversly, the said Parenchyma is usually more or less, di∣sposed into Diametral rays; running through the Bark, after the same manner, as do the hour lines through the margin of the Dial-plat of a Clock or Watch. Whereas here in the Bark of the Trunk, the said Pa∣renchyma is rarely thus disposed into Dia∣metral Rays: nor when it is, are those rays continued to the circumference of the Bark; as in the Bark of the Root they frequently are. What is further observeable in the Texture of the Parenchyma, I shall shew in the description of the Pith.

The Vessels of the Bark, are as I shall al∣so shew, diversifyed many ways. But there are some things, wherein in all sorts of Plants, they agree. First, in standing, most numerously, or near, the inner Margin of the Bark. Secondly, in being always, and only Sap-vessels. I have viewed so many, that at least, I can securely affirm thus much, that if there be any heteroclital Plants, wherein they are found otherwise, there is not one in five hundred. Thirdly,

in being always conjugated or braced toge∣ther in the form of Net-work: although the number and distances of the braces, are very different: as I have already shewed by divers Figures in my Anatomy of Roots.

The Properties, whereby the said Ves∣sels of the Bark are specificated and distin∣guished one from an other, both in the same Plant, and in the several species of Plants are very many. Which properties are not accidental, but such as shew the constant and universal design of nature. All which shall be demonstrated by several Figures, representing so many quarters of the slices of so many kinds of Branches cut transversly.

FIRST then, for the eight first quar∣ters, the Vessels of the Bark are only of two kinds. And those likewise only Lym∣phaeducts. Yet in all the eight, they are in respect both of their proportion, and po∣sition, very different. So in Hazel and Ash they are but few. In Holly and Barberry more. In Apple, Pear, Plum, Elm, still more numerous. And of those three Fruits, in an Apple, or Plum, more than in a Pear.

Again, as their proportion, so likewise their position is divers. For in Holly, the inner Vessels next to the wood stand in rays,

Yet so thick together, as to make one en∣tire Ring. In Hazel, they stand more in oblong parcels. In Barberry they stand like∣wise in parcels, but they are so many half∣ovals. The utmost Lymphaeducts of all three, make three rings.

Again, in Apple, Pear, and Plum, the inmost Lymphaeducts are radiated. The ut∣most are neither radiated, nor make an en∣tire ring; but stand in peripherial parcels. Much after the same manner they also stand in Elm. In Ash, the said Vessels make two rings, but neither of them radiated: the inmost ring consisting of arched parcels, and the utmost of round ones. And where∣as in all the foregoing, the inmost are still contiguous to the wood; and the utmost more or less, distant from the cuts: here, on the contrary, the inmost are distant from the wood, and the utmost contigu∣ous to the cutis.

All the said Vessels in the Barks of the said eight Branches, though I call them Lymphaeducts; because I observe not any of them to emitt any liquour, but what is clear, & less oyly: Yet are they not one, but two distinct kinds of Lymphaeducts. Which is evident, as from some other rea∣sons, so from hence; In that their positions are altogether heterogeneous: Yet in both

constant, regular and uniform. I say, there can be no reason given, why the self same kind or species of Vessels, should have a different, yea a contrary position, and that contrariety not accidental, but regular and constant.

OF the three next quarters sc. the ninth, tenth, and eleventh, the Vessels of the Bark are different in number, position, size, and kind. In Pine, which is the eleventh, they are fewer. In Wallnut, the ninth, more. In Fig, the tenth, most numerous.

So for their position. In pine, the inmost make a radiated ring. The utmost stand stragling up and down, without any cer∣tain order. In Wallnut the inmost make also a radiated ring; The utmost make a doudle ring; not radiated, but of round parcels. In Fig, the inmost make also a ra∣diated ring. But the utmost make a dou∣ble and sometimes treble ring, not of radi∣ated, nor round, but arched parcels.

Thirdly, they are also different in kind. Those I think, of the two former, Wallnut and Fig, are thus different: those certain∣ly, of the Fig, are so; being Lymphaeducts and Lacteals. The Lymphaeducts make the inmost radiated ring. The utmost, which make the other rings in arched parcels, are the Lactifers.

That they are distinct kinds of Vessels, is evident from two reasons. First, from their position in the Bark, which is altoge∣ther unlike, as hath been said. Secondly, from the most apparent diversity of the Liquours or Saps which they contain, and which upon cutting the Branch transversly, do distinctly bleed from them. Which is one way, whereby we do distinguish the Vessels of Animals themselves. As in the Liver, it were hard to say, which is a Blood-vessels, and which is a Bile-vessel, where they are very small, if it were not for the contents of both.

Those in the Bark of Pine, are likewise of two kinds. The inmost are Lymphae∣ducts, as in the two former. The utmost are not Milk-vessels, but Gum-vessels, or Resiniferous. Out of these Vessels, all the clear Turpentine, that drops from the Tree, doth issue.

Besides the difference of their position, and of the liquor which they contain, and bleed; there is yet a third, and that is, their size. Most of them being of so wide a bore, as to be apparent to a naked eye. Whereas that of the Lymphaeducts, can hardly be discovered by the best Micro∣scope.

The same Resiniferous vessels of Pine, are

likewise, by their size, remarkably diffe∣rent from the Milk vessels of Fig. For those of Fig, are, in comparison, exceeding small; every Arch, not beeing a single vessel, but a parcel or cluster of vessels; whereof an hundred or two hundred may make up one arched parcel. Whereas one single Gum vessel in Pine, is sometimes as big as two whole Arched clusters, that is, as two or three hundred of the Milk vessels in a Fig tree. And the said Gum-vessels, or Turpentine-vessels of Pine, being compared with the Lymphaeducts of the same Tree, one Gum-vessel, by a moderate estimate, may be reckoned three or four hundred times wider than a Lymphaeduct. The like prodigious difference in the size of the se∣veral kinds of Vessels of many other Vege∣tables may be observed.

THE three next quarters of Branches, are of Oak, common Sumack, and com∣mon Wormwood. In the Bark-vessels where∣of, there is yet a farther variety observe∣able. For in all or in most of the above named, there are only two kinds of Vessels in the Bark. But in each of these, there are three kinds.

And first, in that of Oak there are two kinds of Lymphaeducts, and one of a sort of Resiniserous. The inmost Lymphaeducts make

a radiated ring, contiguous to the Wood. The utmost Lymphaeducts make also a ring, but not radiated. Those which are a sort of Rosin-vessels, stand in round parcels; the greater parcels betwixt the two rings of Lymphaeducts, and the lesser betwixt the utmost ring and the skin.

That these are different Vessels from both the other, is evident from the diffe∣rence of their position, as aforesaid. And that they are a sort of Resinous, is argued hence; In that, not only Galls are very full of Rosin, but that the Bark of Oak it self is also resinous. For the conveyance of whose resinous parts, it is most unlike∣ly that any other Vessels should subserve, but a peculiar kind; which are therefore properly called Resiniferous.

The next is a Branch of common Sumach. In the Bark whereof, there are likewise three kinds of vessels. First of all, there is a thick radiated ring of Lymphaeducts; standing on the inner margin of the Bark, contiguous with the Wood. These Vessels exhibit their Lympha very apparently. A second kind of Lymphaeducts are situate to∣wards the outer margin of the Bark, and are composed into distinct Arched parcels, all running in a ring.

Betwixt the two kinds of Lymphaeducts

stand the Milk-vessels. Every single Milk∣vessel being empaled or hemmed in with an arch of Lymphaeducts. These Milk-vessels are extraordinary large, almost as the Gum∣vessels of Pine; so as easily to be observed without a Microscope; and without difficulty to admit a Virginal wyer; being two or three hundred times as big as a Lymphaeduct.

The last, is a Branch of common Worm∣wood. In the Bark whereof, there are likewise three kinds of vessels. First of all, there is a thin radiated ring of Lymphaeducts contiguous with the Wood or on the inner margin of the Bark. But the ring is not en∣tire, but made up of several parcels; which are intercepted by as many parenchymous Insertions.

A second sort of Lymphaeducts, or some other Sap-vessels, are situate about the mid∣dle of the Bark: and are composed into arched parcels, which likewise stand all e∣ven in a ring.

Beyond these Arches, and towards the outer Margin of the Bark, stand a third sort of Vessels, somewhat analagous to the Milk∣vessels in Sumach. Yet different from them, in some part, both as to their situation size and Content. For in Sumach, the Milk-vessels stand within the Arched Lymphaeducts: whereas these in Wormwod, stand without them. Like∣wise

being the Vessels of an Herb, they are far less▪ sc. about the compass or width of a spangle. Their content, is not a Milk, but a perfect Turpentine, or a liquid and most oleous gum. Or which, for its pleasant aro∣matickness, may be called a Balsom. For it perfecty giveth whatever is in the smell and taste of Wormwood: being the Essence of the whole Plant, which nature treasur∣eth up in these Vessels. There are divers other, both Herbs and Trees, that in the like Vessels, contain a Turpentine or aroma∣tical Balsom; as Angelica, Enula campanae, and others: the Vessels being so very large, that they may be easily traced with a knife.

Whether in some Plants, there are not more, I cannot say; though we may not have much reason to doubt of it. Because we see, there is so great a variety in the Viscera of Animals. For what the Viscera are in Animals; the Vessels themselves are in Plants.

CONCERNING the Sap-vessels, I have one observation further to subjoyn, sc as to the Texture or Formation of the said Vessels. I have already said, and shewed, in my former Books of Plants, that the Lignous parts of all Vessels are Tubulary. That is, that the Sap is conveyed, by the

length of a Plant, through an innumera∣ble company of small Tubes, Pipes, or Ves∣sels.

The Question may be yet further put. If the stringy parts of the Bark are made of Tubes, what are these Tubes themselves made up of? I answer, that not only these Tubes or Sap-vessels, are Organical them∣selves, but their very sides also, are com∣posed of other Parts, which are Organical, sc. of Lignous Fibers: which Fibers stand∣ing close or contiguous in a round, make one Tubulary Body, which I call the Sap∣vessel of a Plant. And it is most probable, that these Fibers themselves, are also Tu∣bulary. That is, that a Sap-vessel is a small Tube, made up or composed of other yet much smaller Tubes, set round together in a Cylindrical Figure. As if we should ima∣gine a company of straws, which are so many small Pipes, to be joined and set round together, so as to make another greater Pipe, answerable to a hollow Cane. The Cane, I say, is as the Sap-vessels; and the straws, as the Fibers whereof it is compo∣sed. By which also appears, the prodigi∣ous smallness of these Fibers. For a small Sap vessel may, by an indifferent account, be reckoned fifty times smaller than a Horse hair. Allowing therefore but twenty of the

aforesaid Fibers to one Vessel; that is to say, ten to compose its sides, and ten more to fill its concave; then one of the said Fi∣bers, must be a thousand times smaller than a Horse hair. Whether the Fibers are not made up of other Fibers, He only, that made them knows.

The first notice I took of these Fibers, and of the Sap-vessels their being compo∣sed hereof, was in a very white and clear peice of Ash, torn, with some care, by the length of the Tree, and objected to a pro∣per Light. They are also sometimes discern∣able in some other clear Woods, as in very white Fir, &c.

Divers considerations have confirmed me in the truth hereof. Whereof, at pre∣sent, I will mention these two. First, that herein the Analogy betwixt the Vessels of an Animal and a Plant, is very clear and proper. For as the sanguineous vessels in an Animal are composed of a number of Fibers, set round in a Tubulary Figure together: so are these Sap vessels of a Plant. Secondly, in that herein, there is a more genuine re∣spondence betwixt these, and the other Ves∣sels of a Plant it self; sc. the Air-vessels; which are made up of a certain number of round Fibers, standing collaterally, or side to side, as I have also observed in my Anato∣my

of Roots. So that it is the less strange, that the Sap vessels should be made up of Fibers, since the Air-vessels are so likewise. Only with this difference, that whereas in the Air vessels, the Fibers are postured spirally, and so more horizontally or by the bredth of the Trunk: here in the Sap∣vessels, they stand and are continued in strait lines, by the length. And thus far of the Bark.

CHAP. III.

THE next general Part of a Branch is the Wood; which lyeth betwixt the Bark and Pith. And this likewise ever∣more consisteth of two general Parts, sc. of a Parenchymous part, and of Vessels. The Parenchymous part of the Wood though much diversifyed, yet in the Trunks of all Trees whatsoever hath this property, to be disposed into many Diametral rays, or Insertions, running betwixt so many por∣tions of Vessels, from the Bark to the Pith: as in any of the Quarters here before us may appear.

But these Insertions are much diversi∣fied according to the several species of

Plants. So in Barberry, Ash, Pine, Worm∣wood, they are less numerous. In Elm, Wallnut, Fig, Sumach, they are more. And in Holly, Pear, Plum, Apple, Oak, Hazel, are most numerous.

The same Insertions, in Barberry, Worm∣wood, and in Oak many of them are very thick. In Pine, Fig, Ash, of a middle size. In Pear, Holly, and most of them in Oak, are exceeding small. Again, in Barberry, Elm, Ash, Sumach, Fig, they are of an equal size. In Holly, Hazel, Pear, Plum, Oak, they are very unequal: some of those in Holly being four or five times thicker than the rest; in Plum six or seven times; and in Oak ten times at least.

They have yet one more diversity, which is, that in divers of the said Bran∣ches, they run not only through the Wood; but also shoot out beyond it, into some part of the Bark, as in Elm, Sumach, Worm∣wood, &c. Whereas in Pine, and some of the rest they either keep not distinct from the o∣ther parts of the Parenchyma of the Bark; or are so small, as not to be distinguished there from.

The Texture likewise of these Insertions is somewhat various. For in Wormwood, and most Plants they are manifestly com∣posed of small Bubles or Bladders: differing

in nothing from those of the Bark or Pith, saving in their being much less; especially in the Branches of Trees. But in Herbs they are much larger which leads to the better observation of them in Trees likewise. But in many Trees, as Apple, Pear, Plum, Pine, &c. they are either quite lost, or so squeezed and pressed together by the hard Wood standing on both sides, as to be undiscern∣able. So that the difference betwixt a Blad∣der in the Pith, and one of these in the In∣sertions, is only this, that the one is as a purse expanded, and the other as the same purse contracted, and drawn up together with the s••rings.

T•••• Vessels of the Wood, have likewise much 〈◊〉〈◊〉. Yet in the Branches of all Tree••▪ they agree thus far; viz. To be of two general kinds; that is to say, Sap∣vessels and Air-vessels: whereas it is pro∣per to the Bark to have only Sap-vessels. Likewise betwixt the Sap-vessels, or Lignous Vessels of the Bark and of the Wood, there is this difference; That those of the Bark, upon cutting the Branch transversly, do all of them immediately visibly Bleed. But these of the Wood do not, many of them, sometimes; and most of them never.

These Sap-vessels of the Wood have like∣wise some visible variety. Those much

less than have the Air-vessels, as shall be shewed. As for the reason why I call them Sap-vessels, it is to be understood; That every year there grows a new Ring of Sap∣vessels on the inner margin of the Bark. Which Ring hardening by degrees, at the latter end of the year, is turned into a dry and hard Ring of perfect Wood. So that e∣very year, the Bark of the Tree is divided into two parts, and distributed two con∣trary ways. The outer part falleth off to∣wards the skin; and at length becomes the skin it self. In like manner, as the Cu∣ticula in Animals, is but the efflorescence of the Cutis. I say, that the elder skin of a Tree, is is not originally made a skin; but was once, some of the midle part of the Bark it self, which is annually cast off, and dryed into a skin: even as the very skin of an Adder, doth upon the gradual gene∣ration of a new one underneath, in time, become a Slough. The inmost portion of the Bark, is annually distributed and ad∣ded to the Wood: the Parenchymous part thereof making a new addition to the In∣sertions within the Wood; and the Vessels, a new addition to the Lignous pieces betwixt which the Insertions stand. So that a Ring of Sap-vessels in the Bark this year, will be a Ring of Wood the next: and so another

Ring of Sap-vessels and or Wood successively from year to year. So the quarter for an Apple branch, sheweth one of three years growth; that of Barbery, of two; that of Sumach, of one only; that of Elm, of five. Whereby two things may be the better no∣ted. First the difference betwixt the degrees of the annual growths of several Trees: three years growth in an Oak, being as thick as five in an Elm; as, by comparing the se∣venth and twelfth quarters together, is seen. Secondly, the difference betwixt the An∣nual growths of the same Tree; being not of a constant proportion, but varying in thickness, as it should seem, according to the season of the year: whereby it may ap∣pear, what season, or kind of year, doth most of all favour, the latitudinal growth, or the thickening of any Tree.

There is likewise some further variety in these old Sap-vessels, whereof the true Wood consists; represented in Wallnut, Fig, and Oak. Wherein, a certain smaller num∣ber of them stand in a contrary position, to that of the rest; viz. either in small and white Rings, as in Oak; or else in divers white and crooked parcels, as in Wallnut and Fig. For it seemeth, that, at least, in many Trees, some portion of all the kinds of Vessels in the Bark, are not only annu∣ally

distributed to the Wood, but do like∣wise therein retain the same, or very like position, which they originally had in the Bark. So that as all those bigger and dark∣er portions of the Wood, were originally, nothing else but the radiated Lymphaeducts of the Bark: so the little white circles, or parcels of circles, in the same Wood▪ were originally another sort o•• Sap-vessels in the Bark; sc. those which have a circular posi∣tion therein.

Lastly, as the said older Sap-vessels, are varied by their quantity and position; so likewise by their size▪ For ••n Oak, and most hard Woods, they are extraordinary small, just discoverable by a good Micro∣scope. In Wallnut, Fig, Hazel, they are somewhat more patent. But in Fir, and some other Woods of that kind, they are remarkably wider, than in most other Woods. I have seen them in Pine and Fir, ten or fifteen times as big as they are in Oak, and are in some sort represented by the smaller black spots which stand in rays in the eleventh quarter. So that a piece of Fir-wood, especially the whiter sort, looks through a Microscope, just like the Lattice of a Window; or like the perforated Wood, out of which Button▪moulds have been cut.

Of the Branches of Fir, Pine, and o∣thers of the same kindred, it is also to be noted; That, amongst the said Lymphae∣ducts, whereof chiefly the Wood consists; there are scattered up and down some few Gum, or Turpentine-vessels; represented by the larger black spots in the eleventh quarter. Which Vessels are eadem numero, the self same, which did once appertain to the Bark; and do even here also in the Wood, contain and yield a liquid Turpen∣tine. Only being pinched up by the Wood, they are become much smaller Pipes.

THE Air-vessels, with the older Sap∣vessels, and Parenchymous Insertions, al∣together make up that, which is common∣ly called the Wood of a Tree. The Air∣vessels I so call, not in that they never con∣tain any liquor; but, because all the principal time of the growth of a Plant, when the Vessels of the Bark are filled with liquor, these are filled only with a Vapour or vege∣table Air.

In almost all Vegetables, not one in di∣vers hundreds excepted, this is proper to these Air-vessels; To have a much more ample bore or cavity, than any of the Sap∣vessels in the Wood. In the Wood, I say; for in the Bark, there are many Sap ves∣sels bigger than the bigest Air-vessels that are.

The varieties hereof are very many; in respect both of their number, size, and po∣sition; being the same, in no two species's of Plants whatsoever. Frst in respect of their number. So in Hazle, Apple, Pear, they are very numerous; but in different degrees: and are represented in the same Figures, by all the black spots in the Wood. In Holly, Plum, Barberry somewhat nume∣rous. In Oak, Ash, Wallnut fewer. In Pine, and others of that kindred, very few; sc. fewer than in any other kind whatso∣ever.

Secondly, in respect of their size; which from the first or greatest, to the least, may be computed easily to about twenty Degrees. Thus many of those in Elm, Ash, Wallnut, Fig, Oak, are very large. In Barberry and Plum, not so large. In Hazle, Sumach, smaller. In Holly, Pear of a still smaller size. So that many of those in Elm, or Oak, are twenty times bigger, than those in Holly or Pear.

And as they have a different size in di∣vers kinds of Plants; so likewise, accord∣ing to the place where they stand, in the self same. So in Holly, Hazle, Apple, their size is equaller throughout the bredth of the Tree. But in Barberry, Elm, Oak, Ash, their size in each is very different; not fortuit∣ously

alw••ys much after the same manner. For in all the named Branches, the Air∣vessels that stand in the inner margin of each annual Ring, are all vastly bigger, than any of those that stand in the outer part of the Ring.

Thirdly these Air-vessels are also diffe∣rent in their situation. So in Apple, Wallnut, Fig, they are spread all abroad, in every annual Ring; not being posited in any one 〈◊〉〈◊〉 line. In others, they keep more w••thin the compass of some line or lines; 〈◊〉〈◊〉 Diametral, or Peripherial. So in Holly they are radiated, or run in even Diame∣tral lines betwixt the Pith and the Bark. So also are some of them in Hazle; and some few in Wallnut.

Whether they stand irregularly, or are radiated, it is to be noted, that Nature for the most part, so disposeth of them, that many of them may still stand very near the Insertions. So in Apple, she will rather decline making an even line; or in Holly, will rather break that line into parcels, than that the Air-vessels shall stand remote from the Insertions. To what end she doth this, shall be said hereafter.

Again, in Ash, the Air-vessels are none of them radiated, but most of them stand in Circles on the inner Margin of every an∣nual

Ring. Which Circle is sometimes very thick, as in Ash and Barberry. In others but thin, the Vessels standing for the most part single throughout the Circles; as in Elm. Sometimes again, they both make a Circle, and are spread abroad; as in Pear and Plum.

Those likewise which are spread abroad, are sometimes regularly posited. So in Bar∣berry, besides those larger, that make the Circle, there are other smaller ones, that stand, in oblique lines, athwart one ano∣ther; almost like the Bend in an Escut∣cheon. In Oak, they make rather certain Columns, in the posture of the Bar. And in Elm, they make, as it were, many cross Bars, in the posture of the Fess.

This great difference in the size and po∣sition of the Air-vessels, in the same indi∣vidual Plant, is one ground, for which I think it probable, that there are divers kinds of Air-vessels, as well as of Sap-ves∣sels. Even as in Animals there are divers kinds of Organs for spiration, and the separa∣tion of Air: Fishes having their Bronchiae; land Animals their Lungs; and those in Frogs, &c. of a somewhat peculiar kind.

The Texture of these Vessels, and the va∣rious ways whereby they may best be ob∣served I have already shewed, in my Ana∣tomy

of Roots. Yet for our clearer under∣standing the Texture of the said Vessels, I will a little further illustrate the same by this similitude. I would resemble it thus, As if a Ribband should be wound spirally, and edg, to edg, round about a stick; and so the stick being drawn out, the Ribband should be left, in the Figure of a Tube, an∣swerable to an Air-vessel. A Ribband, I say; for that which upon the unroveing of the Vessel, seems to be a Plate; is really Natural Ribband: being not one intire piece, (nor therefore always of the same bredth) but consisting of a certain number of round Fi∣bers, standing collaterally, as the threds do in an Artificial Ribband. And are also, much after the same manner, by other cross and smaller Fibers, stitched close up together; as is most apparent in the large and elder Air-vessels of Pine, Oak, and ma∣ny other Plants. What these cross Fibers are, will better be understood when we come to the Texture of the Pith.

CHAP. IV.

THE third general Part of a Branch, is the Pith. Which though it have a different name from the Parenchyma in the Bark, and the Insertions in the Wood; yet as to its substance, it is the very same with them both. Whereof there is a double evidence, sc. the sameness of their Texture, and their Contin••ity. Their Texture shall be shewed presently. As to their Conti∣nuity, it is to be noted, that as the skin is continuous with the Parenchyma of the Bark; and this Parenchyma likewise, with the Insertions in the Wood; so these Inserti∣ons again, running through the Wood, are also continuous with the Pith. So that the skin, Parenchyma, Insertions, and Pith, are all one entire piece of work; being only filled up diversly, with the Vessels.

The size of the Pith is various, being not the same in any two Branches here repre∣sented. In Wormwood, Sumach, Fig, Bar∣berry, 'tis very large; sc. betwixt 5, and 7. Inches Diameter, as it appears through the Microscope. In Pine, Ash, Holly, Wallnut, not so large; from 3. Inches Diameter to 4. In Oak, Apple, Pear, Hazel, lesser, scarce from 2. to 3. In Damascene, not above an

Inch and half. And in Elm▪ scarce an Inch Diameter. Note also, that of all Plants, Herbs, and Shrubs, have generally the largest Piths, in proportion with the other parts of the same Branch, as in Sumach, Fig, Barberry is manifest.

The Pith for the most part, if not al∣ways, in the Branch, as well as Root, is compounded of two parts, sc. a Parenchy∣ma, and Sap-vessels. The Vessels are here usually postured so, as to make a Ring on the Margin of the Pith. Where they are more numerous, or large, they are more e∣vident; as in Wallnut, Fig Pine, and others. They are also of divers kinds answerable to those in the Bark; as in Wallnut Lym∣phaeducts, in Fig Lactents, in Pine Rosi∣nous.

The Parenchyma of the Pith is compo∣sed of Bladders. Which are the very same with those in the Bark, and in the Inser∣tions within the Wood. Only these in the Pith, are of the largest size; those in the Bark, of a lesser; and those of the Inser∣tions least of all: for which reason they are less obvious than in the Pith.

The Bladders of the Pith, though always comparatively great, yet are of very dif∣ferent sizes. Being easily distinguished, e∣ven as to their horizontal Area, to twenty

degrees. Those of Fig, Barberry, and some others, are large. And of many Plants, as of Thistle, Borage, and others, three times as big again; appearing in the Microscope, like to the largest Cells of an Honey-comb. These of Plum, Wormwood, Sumach, less. Of Elm, Apple, Pear, lesser, Of Holly and Oak, still less. So that the Bladders of the Pith in Borage or common Thistle, are of that size, as to contain, within the compass only of their Horizontal Area, about twenty Bladders of the Pith of Oak. Wherefore one whole Bladder in Thistle, is, at least an hundred times bigger, then another in Oak.

Of the size of these Bladders of the Pith, 'tis also to be noted, that it doth not at all follow the size of the Pith it self; but is still varyed, according as nature designeth the Pith for various use. Thus whereas the Pith of Sumach is larger than that of Barberry; it might be thought, that the Bladders, whereof it is composed, should be likewise larger; yet are they three times as small again. So the Pith of Plum, is far less than that of Pear; yet the Bladders 4. or 5. times as big. So the Pith of Hazel is almost three times as little again, as that of Holly; yet the Bladders in Hazel, are ten times bigger, than in Holly.

The shape of the Bladders hath also some variety. For although, for the most part, they are more round; yet oftentimes they are angular: as in Reed-grass, a Water∣plant; where they are Cubical; and in Bo∣rage, Thistle, and many others, where they are pentangular, sexangular and septangu∣lar.

Of the Texture of the Bladders, 'tis also to be noted, that many times, the sides of the greater Bladders are composed of lesser; as is often seen in those of Borage and some other Plants. In the same man∣ner, as the Sap-vessels, are but greater Fi∣bers made up of lesser.

The Pith, though always originally com∣posed of Bladders, and so one entire piece; yet in process, as the Plant grows up, it hath divers openings or Ruptures made in it: oftentimes very regularly, and always for good use, and with constancy observed in the same Species of Plants. In Wallnut it shrinketh up into transverse films or Membranes; as likewise in Spanish-broom. Sometimes the Membranes reach not from side to side, but about half way, running one against another by a reciprocal In∣denture: somewhat after the manner of the Valvulae Conniventes in the smaller Gutts. Sometimes bored with divers Caverns by

the length: sometimes with one great one throughout the stalk; and sometimes reach∣ing from knot to knot; by which it is di∣vided into several stories: and divers o∣ther ways.

I SHALL conclude this discourse with a further illustration of the Texture of the Pith, and of the whole Plant, as conse∣quent thereupon. I say therefore, (and have given some account hereof in my Anatomy of Roots) that as the Vessels of a Plant, sc. the Air-vessels and Sap-vessels, are made up of Fibers; according to what I have in this discourse above said; so the Parenchyma of a Plant, or the Bladders whereof the Parenchyma consists, are like∣wise made up of Fibers. Which is true also of the Parenchyma of the Bark. And also of the Insertions in the Wood. Yea, and of the Fruit, and all other Parenchy∣mous parts of a Plant. I say, that the very pulp of an Apple, Pear, Cucumber, Plum, or any other Fruit, is nothing els but a Ball of small transparent threds or Fibers, all wrapped and wreathed up (though in a di∣vers manner) close together. And even all those parts of a Vegetable, which are nei∣ther formed into visible Tubes, nor into Bladders, are yet made up of Fibers. Which though it be difficult to observe in any of

those parts which are closer wrought; yet in the Pith, especially of some Plants, which consisteth of more open work, it is more visible; and so introduceth the observa∣tion hereof, in all other Parenchymous parts.

Whence it follows, that the whole sub∣stance, or all the parts of a Vegetable, so far as organical, they are also Fibrous. Of all which Fibers, those of the Vessels, run up by the length of the Plant: these of the Pith, and other Parenchymous parts, run cross by the bredth or horizontally.

BY WHICH means, the said Paren∣chymous Fibers, in fetching their horizon∣tal circles, they first of all weave, and make up the Bladders of the Pith in open-work. And the same Fibers being continued; they next weave and make up the Insertions in close work. Amongst which Insertions the Vessels standing, many of the said Fibers wrap themselves also about them; thus ty∣ing many of them together; and making those several Conjugations and Braces, of the Vessels which I have formerly described. And as some of these Parenchymous Fibers wrap about the Vessels; so also about the very Fibers, whereof the Vessels are, as is above said, composed. By which means it is, that all the said Fibers of the Vessels are

tacked or stitched up close together into one coherent piece. Much after the same manner, as the perpendicular splinters or Twigs of a Basket, are, by those that run in and out horizontally. And the same Pa∣renchymous Fibers, being still further pro∣duced into the Bark; they there compose the same work over again: only not so open as in the Pith.

SO THAT the most unfeigned and proper resemblance we can make of the whole Body of a Plant, is, to a piece of fine Bone-lace, at such time, as the women are working it upon the Cushion. For all the Parenchymous parts, as the Pith, Insertions, and Parenchyma of the Bark, are nothing els but Lace-work; the Fibers of the Pith running Horizontally as do the threds in the Lace: and bounding the several Bladders of the Pith and Bark; as the threds do the several holes of the Lace: and making up the Insertions without Bladders, or ve∣ry small ones, as the same threds likewise do the close parts of the Lace; which they call the cloath-work. And lastly, the Vessels, standing perpendicularly, run cross to the Horizontal Fibers; even as in the Lace, the Pins do to the threds. And this is the true Texture of a Plant: and the general compo∣sure, not only of a Branch, but of all the

other parts, from the seed to the seed. See the Figure representing the stalk of Thistle.