PART II.

HAVING before given the _Anatomy_ of _Trunks_; I shall next proceed to see, what _Use_ may be made thereof; and principally, to explicate the manner of their _Vegetation_. In doing which, that former _Method_, which I used in shewing the manner of the _Growth_ of _Roots_, I shall not exactly follow. For so, in regard the _Organical Parts_ of the _Root_ and _Trunk_ are the same, and consequently their _Nutrition_ and _Conformation_ are effected in the same way; I should hereby be obliged to a nauseous and unprofitable repetition of many things already said. The _Explication_ therefore of all those _Particulars_, which more especially belong to the _Trunk_, or are more Apparent therein, and not spoken of, or not so fully, in the former _Books_, will be my present Task. The chief _Heads_ whereof, shall be these Seven following, _viz._

FIRST, the _Motion_ and _Course_ of the _Sap_.

SECONDLY, The _Motion_ and _Course_ of the _Aer_.

THIRDLY, The _Structure_ of the _Parts_.

FOURTHLY, The _Generation_ of _Liquors_.

FIFTHLY, The _Figuration_ of _Trunks_.

SIXTHLY, The _Motion_ of _Trunks_.

SEVENTHLY, And lastly the _Nature_ of _Trunks_ as variously fitted for _Mechanical Use_.

CHAP. I.

_Of the_ Motion _and_ Course _of the_ Sap.

FIRST, as to the _Course_ of the _Sap_, there are Three _Parts_ in which it _moveth_; _sc._ the _Pith_, the _Wood_ and the _Barque_. First the _Pith_; in which the _Sap_ moveth the _First year_, and _only the First year_. Or, it is _Proprium quarto modo_, to the _Pith_ of every _Annual Growth_, and to the _Pith_ of such a _Growth_ only, _To be succulent_. That is, whether of a _Sprout_ from a _Seed_, or of a _Sucker_ from a _Root_, or of a _Cyon_ from a _Branch_; The _Pith_ is always found the _First year_ full of _Sap_. But the _Second year_, the same individual _Pith_, always becomes _dry_, and so it continues ever after.

2. §. One cause whereof is, that the _Lymphæducts_ in the _Barque_, being the first year adjacent to the _Pith_; they do all that time, transfuse part of their _Sap_ into it, and so keep it always _Succulent_. But the same _Lymphæducts_, the year following, are turned into _Wood_; and the _Vessels_ which are then generated, and carry the _Sap_, stand beyond them, in the _Barque_. So that the _Sap_ being now more remote from the _Pith_, and intercepted by the new _Wood_, it cannot be transfused, with that sufficient force and plenty as before, into the _Pith_; which therefore, from the first year, always continues dry.

3. §. THE SECOND _Part_ in which the _Sap moves_, _sub forma liquoris_, is the _Wood_. Which yet, it doth not in all _Plants_, but only in some; and visibly, in very few; as in the _Vine_: In a _Vine_, I say, the _Sap_ doth _visibly ascend_ by the _Wood_. And this it doth, not only the first year, but every year, so long as the _Vine_ continues to grow. But although this _ascent_, in or through the _Wood_, be every year; yet it is only in the _Spring_, for about the space of a Month; _sc._ in _March_ and _April_.

4. §. There are many other _Trees_, besides the _Vine_, wherein, about the same time of the year, the _Sap ascendeth_, though not so copiously, yet chiefly, in the _Wood_. For if we take a _Branch_ of two or three years growth, suppose of _Sallow_, and having first cut the same transversely; if the _Barque_ be then also transversely, and with some force, pressed with the back of the knife, near the newly cut end; the _Sap_ will very plainly rise up out of the utmost _Ring_ of _Wood_. And if it be pressed in the same manner, or a little more strongly, about an Inch lower, the _Sap_ will ascend out of every _Ring_ of _Wood_ to the Center. Yet at the same time, which is to be noted, there _ariseth_ no _Sap_ at all out of the _Barque_.

5. §. Whence appears the Error of that so Common Opinion, That _the Sap always riseth betwixt the Wood and the Barque_. The contrary whereunto is most true, That it never doth. For the greater part of the year, it riseth in the _Barque_, _sc._ in the inner _Margin_ adjacent to the _Wood_, and in _Spring_, in or through the _Wood_ it self, and there only.

6. §. THE THIRD _Part_ in which the _Sap_ ascends, is the _Barque_, as was above hinted, and may be observ’d in almost any _Branch_, if cut cross, in the _late Spring_ and in _Summer_; either as the _Sap_ issueth spontaneously, or upon pressing, as aforesaid. So that when the _Sap_ ceaseth to ascend, _sub forma liquoris_, by the _Wood_, then it begins to ascend by the _Barque_.

7. §. Besides the difference of _Time_, the _Organical Parts_ likewise, in which these two _Saps_ ascend, are divers. For in the _Barque_, it ascendeth _visibly_, only in the _Succiferous_, whereas in the _Wood_, it ascendeth only by the _Aer-Vessels_.

8. §. FROM what hath been said, we may understand, what is meant by the _Bleeding_ of _Plants_. If we take it generally, it properly enough expresses, _The eruption of the Sap out of any Vessels_. And so, almost all _Plants_, in _Summer_ time, do _Bleed_, that is, from _Sap-Vessels_, either in the _Barque_, or in the _Margin_ of the _Pith_: the _Saps_ they _Bleed_, having either a _Sower_, _Sweet_, _Hot_, _Bitter_, or other _Tast_. At which time, the _Vessels_ also, in the _Barque_ of a _Vine-Branch_, do _Bleed_ a _Sower Sap_.

9. §. But that which is _vulgarly_ called _Bleeding_, as in a _Vine_, is quite another thing; both as to the _Liquor_ which issueth, and the _Place_ where it issues: that is to say, it is neither a _Sweet_, nor _Sower_, but _Tasteless Sap_; issuing, not from any _Vessels_ in the _Barque_, but from the _Aer-Vessels_ in the _Wood_. So that there is as much difference betwixt _Bleeding_ in a _Vine_, or the _Rising_ of the _Sap_ in any other _Tree_, in _March_, and in _July_; as there is betwixt _Salivation_ and an _Hæmorrhage_; or betwixt the _Course_ of the _Chyle_ in the _Lactiferous Vessels_, and the _Circulation_ of the _Blood_ in the _Arteries_ and _Veins_.

10. §. NOW the Cause from whence it comes to pass, that the _early Spring-Sap_ of a _Vine_, and other _Trees_, ascendeth by the _Wood_, is, In that the _Generation_ of the young _Sap-Vessels_ in the _Barque_, by which the _Sap_ ascendeth all the _Summer_; is, in the beginning of _Spring_, but newly attempted. So that the _Sap_ having not yet these _Vessels_ to receive it, it therefore (_pro hac vice_) runs up the _Aer-Vessels_ in the _Wood_. But so soon as the said _Vessels_ in the _Barque_ begin to be considerably encreased, the _Sap_, declining the _Aer-Vessels_, betakes it self to _These_, as its most proper _Receptacles_.

11. §. THE CAUSE also, why the _Vessels_ of almost all _Plants_, upon cutting, do yield _Sap_, or _Bleed_; is the _Pressure_ which the _Parenchyma_ makes upon them. For the _Pith_ and other _Parenchymous Parts_ of a _Plant_, upon the reception of _Liquor_, have always a _Conatus_ to _dilate_ themselves. As is manifest from _Sponges_, which are a Substance of the same Nature, and have a somewhat like structure. As also from _Cork_, which is but the _Parenchyma_ or _Barque_ of a _Tree_. I say therefore, that the _Parenchyma_ being fill’d and swell’d with _Sap_, hath thereby a continual _Conatus_ to _dilate_ it self; and in the same degree, to press together or contract the _Vessels_ which it surroundeth. And the said _Vessels_ being cut, their actual _Contraction_ and the _Eruption_ of the _Sap_, do both immediately follow.

12. §. IT may be also noted, That the _Trunk_ or _Branch_ of any _Plant_ being cut, it always _bleeds_ at both ends, or upwards and downwards, alike freely. Which, as well as divers other _Experiments_ plainly shews, That in the _Sap-Vessels_ of a _Plant_, there are no _Valves_.

13. §. FROM what we have now above, and elsewhere formerly said, we may also understand the _manner_ of the _Ascent_ of the _Sap_. As to which, I say, _First_, That considering to what height and plenty, the _Sap_ sometimes ascends; it is not intelligible, how it should thus ascend, by virtue of any one _Part_ of a _Plant_, alone; that is neither by virtue of the _Parenchyma_, nor by virtue of the _Vessels_, alone. Not by the _Parenchyma_ alone. For this, as it hath the Nature of a _Sponge_ or _Filtre_, to suck up the _Sap_; so likewise, to suck it up but to a certain height, as perhaps, about an Inch, or two, and no more.

14. §. Nor by the _Vessels_ alone, for the same reason. For although we see, that small _Glass-Pipes_ immersed in Water, will give it an ascent for some Inches; yet there is a certain _period_, according to the _bore_ of the _Pipe_, beyond which it will not rise. We must therefore joyn the _Vessels_ and the _Parenchyma_ both together in this Service; which we may conceive performed by them in the manner following.

15. §. Let A B be the _Vessel_ of a _Plant_. Let C E D F be the _Bladders_ of the _Parenchyma_, wherewith, as with so many little _Cisterns_, it is surrounded. ♦ _Tab. 39._ ♦ I say then, that the _Sap_, in the _Pipe_ B A, would, of it self, rise but a few Inches; as suppose, from D to L. But the _Bladders_ D P, which surround it, being swelled up and turgid with _Sap_, do hereby press upon it; and so not only a little contract its bore, but also transfuse or strain some _Portion_ of their _Sap_ thereinto: by both which means, the _Sap_ will be forced to rise higher therein. And the said _Pipe_ or _Vessel_ being all along surrounded by the like _Bladders_; the _Sap_ therein, is still forced higher and higher: the _Bladders_ of the _Parenchyma_ being, as is said, so many _Cisterns_ of _Liquor_, which transfuse their repeated Supplies throughout the length of the _Pipe_. So that by the supply and pressure of the _Cisterns_ or _Bladders_ F D, the _Sap_ riseth to L; by the _Bladders_ Q L, it rises to M; by the _Bladders_ N M, it rises to I; by the _Bladders_ O I, it rises to K; by the _Bladders_ P K, it rises to E; and so to the top of the _Tree_. And thus far of the _Motion_ of the _Sap_.

CHAP. II.

_Of the_ Motion _and_ Course _of the_ Aer.

THE NEXT enquiry to be made, is, into the _Motion_ and _Course_ of the _Aer_. Where this question will first of all be asked; _sc._ Which way the _Aer_ first _enters_ the _Plant_; whether at the _Trunk_, _Leaves_, and other _Parts_ above ground; or at the _Root_? _I_ answer, _That it enters in part, at them all_. For the _Reception_, as well as _Extramission_ whereof, the _Pores_ are so very large, in the _Trunks_ of some _Plants_, as in the better sort of thick walking _Canes_, that they are visible, to a good Eye, without a _Glass_; ♦ _Tab. 19._ ♦ but with a _Glass_, the _Cane_ seems, as if it were stuck top full of holes with great _Pins_: being so large, as very well to resemble the _Pores_ of the _Skin_ in the end of the _Fingers_ and _Ball_ of the _Hand_.

2. §. In the _Leaves_ of _Pine_, they are likewise through a _Glass_, a very Elegant Show; standing all most exactly, in _rank_ and _file_, throughout the length of the _Leaves_. The _Figure_ whereof shall be given hereafter, when we come to the _Anatomy_ of the _Leaf_.

3. §. But although the _Aer_ enters, in part, at the _Trunk_ and other _Parts_, especially in some _Plants_; yet its _chief_ entrance, is at the _Root_. Even as some Parts of _Aer_, may continually pass into the _Body_ and _Blood_, by the _Habit_, or _Pores_ of the _Skin_; but the chief entrance hereof, is at the _Mouth_. And what the _Mouth_ is, to an _Animal_; that the _Root_ is to a _Plant_.

4. §. Again, if the chief entrance of the _Aer_, were at the _Trunk_; then, before it could be mixed with the _Sap_ in the _Root_, it must descend; and so move not only contrary to its own Nature, but likewise in a contrary Course to the _Sap_, throughout the _Plant_. Whereas, by its _Reception_ at the _Root_, and so its _Transition_ from thence; it hath a more natural and easie motion of Ascent. For while the _Sap_ ascends, that the _Aer_, in the same _Plant_, should continually descend, cannot reasonably be supposed.

5. §. The same is further argued, From the fewness and smallness of the _Diametral Portions_ in the _Trunk_ in comparison with those in the _Root_. In which _Nature_ hath plainly designed the same, for the _Separation_ of the _Aer_ from the _Sap_, after they are both together received thereinto. So that the _Reception_ and _Course_ of the _Aer_, is made on this manner following.

6. §. THE _Aer_ being a _Springy_ Body, it insinuates into all the _Holes_ and _Cranies_ of the _Earth_; and so is plentifully mixed therewith. Whereupon, as the _Sap_ enters the _Root_, more or less _Aer_ still intrudes it self together with it. The _Liquid_ Portion of the _Sap_, swells and fills up the _Succulent Parts_ of the _Barque_. The _Aery_ Part, is, as was said, separated from the _Liquid_, into the _Diametral_ Portions. Which running from the _Barque_ towards the Centre of the _Root_, and so passing along betwixt the _Aer-Vessels_; do hereby convey the _Aery_ Part of the _Sap_ from the _Barque_, into the same.

7. §. Being thus received into the _Aer-Vessels_, and the _Reception_ thereof, by the same means continued; it is by them advanced into the _Trunk_. In which advance, it is again, more or less, disbursed into all the _Parts_ of the _Trunk_, as it goes. _Partly_, inwards to the _Pith_. From whence, the _Pith_ is always, at length, filled with _Aer_. _Partly_, into the _Insertions_; by which it is conveyed outward into the _Barque_. Wherein, it is in some part, transfused through the _Sap_: and so the rest, with part of the _Sap_, remitted, in _perspirations_, back again into the _Aer_.

8. §. So that, whereas the _Diametral Portions_ in the _Root_, do serve to convey the _Aer_ from the _Sap_ in the _Barque_, into the _Aer-Vessels_, in the _Wood_: on the contrary, the _Insertions_ here in the _Trunk_, serve to convey the _Aer_ from the _Aer-Vessels_ in the _Wood_, into the _Sap_, in the _Barque_. Wherefore, as the _Aer-Vessels advance_ the _Aer_, or the _Aery Part_ of the _Sap_, and so convey it by the _length_ of the _Trunk_; so the _Insertions filter_ it, and convey it by the _breadth_.

9. §. AND that the _Insertions_ have this _Office_ or _Subservience_ unto both _Kinds_ of _Vessels_; doth yet further appear, if we consider, That the _Aer-Vessels_ are always so postured, as to touch upon the said _Insertions_, or at least to stand very near them. For either they are large, and so do frequently touch upon them on both sides; as in _Elm_, _Ash_, _Wallnut_, &c. ♦ _Tab. 28. 29. 22._ ♦ Or if they are small; then they either run along in even lines collateral and oftentimes contiguous with the said _Insertions_, as in _Holly_: or at least, are reciprocally, some on one side, and some on another, inclined to them; as in _Apple_. ♦ 25. ♦ By all which means, the _Aer_ is more readily conveyed from the _Vessels_ into the _Insertions_.

10. §. A further evidence hereof is this, That generally, the bigger and the more numerous the _Aer-Vessels_ be; the bigger, or at least, the more numerous also are the _Insertions_: Especially, if the comparison be made (as in all other cases it ought to be, as well as here) betwixt the several _Species_ of the same _Kind_. So _Corin_, which hath small _Aer-Vessels_, ♦ _Tab. 17._ ♦ hath also very small _Insertions_. But the _Vine_, hath both very large: and so for others.

11. §. Wherefore, the _Insertions_ minister betwixt the _Aer-Vessels_, and the _Succiferous_; in the same manner, as the _Vesiculæ_ of the _Lungs_, do betwixt the _Bronchiæ_ and the _Arteries_. That is to say, as in an _Animal_, the _Bronchiæ_ deposite the _Aer_ into the _Vesiculæ_ of the _Lungs_; which administer it to the _Arteries_: so in a _Plant_, the _Aer-Vessels_ deposit the _Aer_ into the _Insertions_, that is into the _Vesiculæ_ of the _Insertions_; by which it is gradually _filtred_ off into the _Barque_ and the _Sap-Vessels_ therein.

CHAP. III.

_Of the_ Structure _of the_ Parts.

A THIRD enquiry, is into the _Generation_ and _Structure_ of _Parts_. The manner whereof I have already endeavoured to _explicate_[61] from the _Anatomy_ of the _Root_, throughout all particulars. Some whereof I shall yet further clear.

[61] _Lib. 2. P. 2._

1. §. As _First_, the _Union_ of the _Barque_ to the _Body_ of the _Tree_, Contrary to the common Opinion, _That they are not continuous_; but that the _Barque_ only surrounds the _Body_, as a _Scabbard_ does a _Sword_, or a _Glove_ the _Hand_. As also seemeth to be proved, by the easy _Slipping_ of the _Barque_ of _Willow_, and most other _Trees_, when full of _Sap_, from the _Wood_.

2. §. But, notwithstanding this, they are as truly continuous, as the _Skin_ of the _Body_ is with the _Flesh_: _sc._ by means of the _Parenchyma_; which is one entire _Body_, running from the _Barque_ into the _Wood_, and so uniting both together; ♦ _Tab. 19._ ♦ as in a _Branch_ of _Vine_ or _Corin-Tree_, when the _Barque_ is stripped off, is apparent; the Spaces between the several _Parts_ of the _Wood_, being filled up with the _Parenchymous_, inserted from the _Barque_.

3. §. Now the reason why the _Barque_ nevertheless slips so easily from the _Wood_, is plain, _viz._ Because most of the young _Vessels_ and _Parenchymous Parts_, are there every year successively formed; that is, betwixt the _Wood_ and _Barque_: where the said _Parts_ newly formed, are as tender, as the tenderest _Vessels_ in _Animals_. And we may imagine, how easie it were at once to tear or break a thousand _Vessels_ or _Fibres_ of an _Embrio_, of a _Womb_ or _Egg_.

4. §. THE same _Vessels_ of the _Barque_ being always _braced_, and gradually falling off, together with the _Parenchyma_, into the utmost _Rind_: Hence it is, that the _Barques_ of many _Trees_, are as it were, ♦ _Tab. 19._ ♦ latticed with several _Cracks_ of divers _Sizes_, and sometimes in the _Figure_ of _Rombs_: the said _Fissures_ representing the _Position_ and _Tract_ of the _Vessels_ in their _Braces_. Hence also it is, that the _Barque_ of some _Trees_, as of _Corin_, _Cherry_, &c. falleth off in _Rings_, _sc._ because the _Sap-Vessels_ are posited in the same manner in the _Barque_.

5. §. The _Sap-Vessels_, as they are generated at the inner _Verge_ of the _Barque_: so likewise, in a small quantity, at the utmost _Verge_ of the _Pith_. These being not only fed with a more vigorous _Sap_, but with great caution, secured within the _Wood_, for the propagation of the succeeding _Buds_.

6. §. Hence also it is, that is, by the annual accretion of these _Vessels_, that the _Pith_ is sometimes less in the _Trunk_, than in the _Branches_; ♦ _Tab. 18._ ♦ and less in the elder _Branches_, than in the younger; and sometimes ’tis almost wholly filled up. By which means, as the _Branches_ carry every year a greater burthen; so they become still more sturdy the better to support it.

7. §. SOMETIMES also the _Pith_ breaks and shrinks up, thus making the _Trunk_ a _Pipe_. The cause whereof, is either the _Largeness_ of its _Pores_, or the _Thinness_ of the _Sides_ of the said _Pores_; upon both which accounts, the _Pith_ doth more easily tear, and upon tearing shrink up, and so become hollow: as in _Cichory_, _Lampsana_, _Sonchus_, _Teasel_, _Brownwort_, and others; wherein the _Pores_ of the _Pith_ are _Large_, and the _Sides_ of the _Pores_, _Thin_. Whereas, upon contrary accounts, the _Piths_ of most _Trees_, remain perpetually entire.

8. §. THE Reason why _Plants_ are made thus to become _hollow_, is _partly_, for the _ripening_ of the _Fruit_ or _Seed_; which is the better effected by a more plentiful supply of _Aer_ continually received into their hollow _Trunks_. For by means of that _Aer_, part of the _Sap_, is dryed up, and the remaining part of it made warmer, and so sooner matured.

9. §. _Partly_, for the better determining the due _Age_ of the _Plant_. Hence it is, that the greater part of _Annual Trunks_, are hollow: the _Aer_ contained in that hollow, drying up the _Sap_, and shrinking up the _Sap-Vessels_ so far, as to hinder the free motion of the _Sap_ therein; from whence the _Plant_ must needs perish. So that as the _Content_ of the _Aer-Vessels_, is a kind of _Vegetable Aer_, whose Office is to _Attenuate_, and _Ferment_ the _Juyces_ of _Plants_: so the _Content_ of these _Cavities_, cometh nearer to a more common _Aer_, designed chiefly, so soon as it is convenient, to _dry_ them up.

10. §. AGAIN, as to the _Aer-Vessels_, divers questions may be asked. As how it comes to pass, that they are generally less in the _Trunk_ of the same _Plant_, than in the _Root_? The Cause whereof is, that here in the _Trunk_ they are more under the power of the _Aer_; both that which entreth in at the _Trunk_, and that which of its own _Nature_ ascendeth up into it from the _Root_. For the _Aer_, as we have elsewhere said, is the _Mould_ of the _Aer-Vessels_; to whose crooked or at least, _Acid Parts_, the _Saline_, and other _Principles_ concurring to their generation, do conform. To which they do best, the smaller they are: the _Fibres_ of the larger _Aer-Vessels_ making greater _Circles_, and so coming nearer to a _right Line_, answerable to the _Figure_ of the Particles, not of the _Aerial_, but of the _Saline Principle_.

11. §. Wherefore as the _Aer-Vessels_ may be observed still to be dilated or widened towards the lower parts of the _Root_, the _Aerial Principle_ being there less predominant, and the _Saline_ more: So towards the upper part of the _Trunk_, to be contracted or grow smaller; the _Aerial Principle_ being here more predominant, and the _Saline_ less.

12. §. FOR the same cause it may be observed, That the _Aer-Vessels_ of the Second years Growth, and the several years succeeding, are usually nearer of one Size, than those of the _Second_ and _First_; all being under a less power of the _Aer_, than the _First_. For the first year the _Pith_ being full of _Liquor_, the _Aer-Vessels_ themselves, are the only _Repositories_ of the _Aer_. Whereas after the first year, the _Pith_ becoming dry, or another great _Repository_ for the _Aer_; the _Aer-Vessels_ are henceforth filled with a moister or more _Vaporous_ and _Saline Aer_, and so made to grow wider.

13. §. Hence the very _Size_ of the _Pith_, hath much _influence_ upon the _Aer-Vessels_, and the manner of _Nutrition_, and the _Generation_ of _Liquors_ in _Plants_.

14. §. BUT for the most part, the _Aer-Vessels_ are somewhat, more or less, amplified in every new _Annual Ring_; or at least to a certain number of years. Probably, because in the elder _Branches_, the _Spiral Fibres_, of which the _Vessels_ consist, are more bulky; and so make a _Vessel_ of a wider, as a more agreeable bore. Nature obtaining hereby, that the Quantity of _Aer_, shall always be answerable to the Growth of the _Plant_, or at least, be sufficient to maintain its _Vegetable Life_ and _Vigour_.

15. §. And therefore, as is above hinted, it seems likely, That after a certain number of years, the _Aer-Vessels_ are no longer amplified, but stand at a stay, and perhaps may grow smaller, according as the _Tree_ is less or more _Longæve_; and that after this period, it is some way or other in its Declining State.

16. §. LASTLY, from the _Content_ and _Governing Principle_ of the _Aer-Vessels_, the _Time_, when they begin every year to be formed, or to appear, is always _later_; at least with respect to the _season_ of the _Tree_. So that whereas the _Sap-Vessels_ begin to be formed in _Spring_: these, not till the latter end of _Summer_, or there about; at least not till about that time to _appear_. That is, when the _Sap_ begins to decrease, and to grow more _Aery_; and so more fit matter for the _Generation_ of the said _Aer-Vessels_.

CHAP. IV.

_Of the_ Generation _of_ Liquors.

UPON the _Structure_ and _Formation_ of the _Parts_, dependeth the _Generation_ of _Liquors_, as was lately intimated. The _manner_ whereof I have formerly shewed, in discoursing of the _Root_. Yet some things I shall here further _explicate_. And _First_, what we have formerly asserted, _sc._ That the concurrence of two _specifically_ distinct _Fluids_, is as necessary to _Nutrition_ in _Plants_, as in _Animals_. Which appears, as from divers other considerations, so from the very _Structure_ of a _Plant_: where in all the _Organical Parts_, or the _Parenchyma_ and the _Vessels_, are every where mixed together _per minima_, that is, _per minimas partes organicas_, or _Fiber_ with _Fiber_ of several _Kinds_. Every small part of a _Tree_, or of the _Barque_ of a _Tree_, being as I may say, a sort of _Linsy-Woolsey_. So that there is not the least part of the _Sap_, which is not impregnate with divers _Essential Tinctures_, as it is continually _filtred_ from the _Fibres_ of _one Kind_, to those of another; standing every where _woun’d_ and _stitch’d_ up together for the same purpose.

2. §. FROM the special _Nature_ and _Structure_ of the _Parts_, the _Liquors_ of _Plants_ are likewise _specified_. The _Vessels_ being the chief _Viscera_ of a _Plant_. For all _Liquors_ in a _Plant_, are certainly made by that _Plant_. And since the _Plant_ hath no _Viscera_ (so called) I would then know, what its several _Liquors_ are made by? If in the _Parenchyma_, surely by that _Parenchyma_. If in the _Vessels_, by the _Vessels_. And if of divers _Kinds_ by divers _Kinds_ of _Vessels_. So that what the _Viscera_ are in _Animals_, the _Vessels_ themselves are in _Plants_. That is to say, as the _Viscera_ of an _Animal_, are but _Vessels conglomerated_: so the _Vessels_ of a _Plant_, are _Viscera drawn out at length_.

3. §. AGAIN, as the _specifying_ of the _Sap_ dependeth chiefly on the special _Nature_ of the _Parts_: so partly, upon the _Structure_ of the _Whole_. Whereby every _Part_ is still better accomodated with its own _Juyce_. Thus the _Aer-Vessels_ are necessary, not only and barely for a _supply_ of _Aer_; but also by their _Number_, _Size_, and _Position_ to _adjust_ the quantity of that _Aer_, to the government of _Nutrition_, and the _Generation_ of the _Specifick Liquors_ of every _Plant_. Which is evident from hence, in that they do not follow the _Size_ of the _Plant_; but are great and many, in some small _Plants_; and small and few, in some others that are large. So _Vines_, and _Corn_, as we have formerly observed, have proportionably a great number of _Aer-Vessels_, and those very large. By which means the _Sap_ is _attenuated_ and less _Oyly_, and more copiously impregnated with a _Subtle_, _Volatile_ and _Winy Spirit_.

4. §. For the same reason, the _Stalk_ of _Maze_ or of _Indian Wheat_, which when it is _Green_ yieldeth a very sweet _Juyce_; and the _Canes_, whereof _Sugar_ (which aboundeth with a _volatile_ and _inflammable Spirit_) is made; these, I say, obtain the like over proportion of _Aer-Vessels_, to what we see in most other _Plants_. Hence also it is, that none of the said _Plants_ have any considerable _Barque_; that so the attenuating and subtilizing _Aer_, may have a more easie and plentiful admission at the _Trunk_ also. For which reason likewise the _Pores_ of the _Skin_ of some _Canes_ are, as hath been said, remarkably wide.

5. §. Hence also it is observable, that of the same _Species_ or _Kindred_, those _Plants_ which have the most, and especially the largest _Aer-Vessels_; have also the greatest abundance either of a _sweet_, or of a _winy Liquor_. So in _Apple_; they are larger than in _Crab_; In _Warden_, larger than in _Quince_; and in _Pear-Tree_, larger than in _Warden_. So also in _Corin_, larger than in _Gooseberry_; and in _Vine_, larger than in _Corin:_ and so in others.

6. §. AND as the _Aer-Vessels_, by their _Multitude_ and _Largeness_, are accommodated to the better making of a _Winy Sap_: so by their _fewness_ and _smallness_, of an _Oylie_. As is remarkably seen in _Fir_, and other _Resiniferous Trees_: these having, if not the _smallest_, yet the _fewest Aer-Vessels_ of all other _Trees_.

7. §. IF it be asked, how a _Plant_ comes to have any _Oyl_ at all in any _Part_? Since we see, that the _Sap_ by which the _Root_ is fed, seemeth to be nothing else but _Water_: and that many _Plants_ which yield a great deal of _stillatitious Oyl_, as _Mint_, _Rue_, and others, will yet grow in _Water_: I say, if it be enquired how this _Water_, is made _Wine_ or _Oyl_? I answer, that there is no such matter. But that the _Oyl_, and all other _Vegetable Principles_ are actually existent in, and mixed _per minima_, though in an extraordinary small proportion, with the _Water_. Even as we see the distilled _Waters_ of _Anise Seeds_, _Penyroyal_, and the like to be impregnated with their own _Oyls_, which give the _Taste_ and _Smell_ to such _Waters_.

8. §. Wherefore, as a certain quantity of any _Salt_ may be dissolved in _Water_; beyond which, it will not mix therewith, but remains under its own _Form_: So is there a certain proportion of _Oyl_, though far less, which may also be perfectly mixed with _Water_; and is certainly so, more or less, with all the _Water_ in the world. But if that proportion, or degree of impregnation be once exceeded; the particles of _Oyl_ do then, and not till then, gather into a body, and appear under their own _Form_.

9. §. I say therefore, that all kinds of _Vegetable Principles_, are either in or together with the _Water_, with less difference first received into a _Plant_. But when they are once therein; they are then _separated_, that is to say, _filtred_, some from others, in very different _Proportions_ and _Conjunctions_ by the several _Parts_; the _Watery_ by one _Part_, the _Aery_ by another, the _Oyly_ by another, and so the rest: and so every _Part_ is the _Receptacle_ of a _Liquor_, become peculiar, not by any _Transformation_, but only the _Percolation_ of _Parts_ out of the _common Mass_ or _Stock_ of _Sap_. And so all those parts of the _Sap_, which are _superflous_ to any kind of _Plant_, are at the same time, discharged back by _Perspirations_, into the _Aer_.

10. §. AND, that _Nature_, in the various _Percolations_ and _Sepations_ of the _Sap_, may still the better answer her end; hence, it is, that she carefully seeth, not only to the special _Nature_ and _Proportion_ of the _Organs_, by which she doth her work; but likewise to their very _Position_. Thus it is observable, That whereas the _Lymphæducts_, which carry a more _Watery Liquor_, are still placed on the inner _Verge_ of the _Barque_, next to the _Aer-Vessels_: the _Lactiferous_ and _Resiniferous Vessels_ of _Plants_, to whose _Oylie Liquor_ a mixture of much _Aer_ is incongruous; do usually stand, neither on the inner, nor the outer verge of the _Barque_; but in the _midle_. By which means, they are at the greatest distance, and so most secure, from the _Aer_; either that which enters the _Barque_ at the Circumference, or from the _Wood_ and _Pith_.

11. §. AND because the _Resinous Liquors_ of _Plants_ are more _Oily_, than their _Milky_; their security therefore, from the approach of the _Aer_, is yet further contrived. In that in _Pine_, and other _Resinous Trees_, the _Diametral Insertions_ are never found; or at least, not _visible_: which yet in other _Trees_, are _conspicuous_; being those _Parts_, whose office it is, to introduce the _Aer_ from the _Aer-Vessels_ into the _Barque_.

12. §. AGAIN, the _Milky Liquors_ of _Plants_ being thinner than the _Resinous_, and having a considerable quantity of _Water_ mixed with their _Oyl_; hence it is, that in _Milky Plants_, as in _Rhus_, there are a greater number of _Lymphæducts_; and those standing nearer to the _Milky Vessels_, than they do in _Pine_ and the like, to the _Resinous_. By which means they are better fitted to affuse their _Aqueous Parts_ more plentifully to the said _Milky Liquor_.

13. §. FROM the _Mixture_ of _Watery Parts_ with the _Oylie_, it comes to pass, that whereas all _Lympha’s_, _Mucilages_, and _Rosins_ are transparent; the _Aquæ-oleous Liquors_ of _Plants_ are _Milky_ or white, or otherwise _Opacous_. For the same thing is the cause of the whiteness of _Vegetable_, as of _Animal-Milk_: that is to say, a more copious mixture of _Watery_ and _Oily Parts per minima_, or into one Body. For even the _Serous_ and _Oylie Parts_ of _Animal Milk_, when throughly separated one from the other, they become very transparent. So the _Stillatitious Oyl_ of _Anise Seeds_, is most transparent and _limpid_, even as _Water_ it self: yet there is a known sort of _White Anise-Seed Water_, as it is commonly called: that it is to say, wherein the _Oyl_, in distillation, ariseth and is mixed more plentifully with the _Water_. And the _Water_, wherein the stillatitious _Oyl_ of any _Vegetable_ is dissolved, becomes a perfect white _Milk_; as in this _Honourable and Learned Presence_, I have formerly had occasion to shew the Experiment.[62]

[62] See the _Discourse_ of _Mixture_

14. §. AND that the _Milky Liquors_ of all _Vegetables_ whatsoever, are more _Oylie_ than their _Lympha’s_, is most certain. For all those _Gums_, which dissolve either in _Oyl_ or in _Water_, as _Galbanum_, and the like, are originally the _Milky Juyces_ of _Plants_. And if you take the _Milk_ of any _Plant_, as for instance, the _Milk_ of common _Sumach_, or of any _Taste_, _Bitter_, _Astringent_, _Hot_, _Cold_, or any other whatsoever; and having well _dryed_ it, and then fired it at a candle; it will thereupon burn with a very bright and durable flame, even like that of _Tar_ or _Turpentine_ it self.

15. §. FROM what hath been said, we may likewise gather the most genuine import of the word _Gum_, and the distinction thereof both from a _Rosin_ and a _Mucilage_. First, a _Rosin_, is originally a _Turpentine_, or _Acidoleous Liquor_, having an exceeding small quantity of _Watery Parts_ mixed therewith; and which, for that reason, will not be dissolved in _Water_, but only in _Oyl_. Of this kind are _Mastick_, _Benzoine_, _Taccamahacca_, and divers others, commonly, in our _Bils_ to _Apothecaries_, called _Gums_. Yet in strict speaking they are all so many _Rosins_.

16. §. Secondly, a _Gum_, and every _Oylie Gum_, is originally a _Milky Liquor_, having a greater quantity of _Water_ mixed with its _Oyly Parts_; and which for that reason, will be made to dissolve either in _Water_ or _Oyl_. Of this kind are _Sagapen_, _Opopanax_, _Ammoniac_, and others.

17. §. The third sort of _Gum_, is that which is _Unoylie_, and which therefore dissolveth only in _Water_, as _Gum-arabick_, the _Gum_ of _Cherry-Tree_, and others such like. This _Gum_, though commonly so called, yet is properly but a dryed _Mucilage_: being originally nothing else but the _Mucilaginous Lympha_ issuing from the _Vessels_ of the _Tree_. In like manner, as it doth from _Cumfry_, _Mallow_, and divers other _Plants_: and even from the _Cucumer_. The _Vessels_ whereof, upon cutting cross, yield a _Lympha_, which is plainly _Mucilaginous_, and which being well dryed, at length becomes a kind of _Gum_, or rather a hardened _Mucilage_. In like manner, the _Gums_ of _Plum-tree_, _Cherry-tree_ and the like, are nothing else but _dryed Mucilages_. Or, if we will take the word in its widest sense, then all _Gums_ are originally, either a _Terebinth_, or a _Milk_, or a _Mucilage_.

18. §. I have likewise made divers Observations of the _Tasts_, _Smells_, and _Colours_ of _Plants_, and of their _Contents_, since those I last published: and that both for the finding out the true _Causes_ of their _Generation_, and also the applying of them unto _Medical_ and other _Uses_. Of which hereafter.

CHAP. V.

_Of the_ Figuration _of_ Trunks.

THE _Fifth Head_, shall be, of the _Figuration_ of _Trunks_. Which also, as well as the _making_ of _Liquors_, dependeth upon the _Structure_ of the _Parts_. As _First_, almost all _Shrubs_ (_cæteris paribus_) have a greater number of _Aer-Vessels_; and those of a smaller Size; and consequently much spread abroad, as most easily yielding to the _magnetick_ Power of the _Aer_, according as we have more fully demonstrated, in speaking of the _Vegetation_ of _Roots_: as in _Elder_, _Hazel_, _Fig_, _Sumach_, and the like. By which spreading, the said _Aer-Vessels_ do sooner, and more easily strike into the _Barque_, and so produce collateral _Buds_ and _Branches_, and that upon the first rising of the _Body_ from the _Root_: that is, the _Plant_ becomes a _Shrub_.

2. §. BUT if the said _Aer-Vessels_ are very large, they will not yield so easily to shoot out collaterally; and so the _Trunk_ grows up taller and more entire: as in _Oak_, _Wallnut_, _Elm_, &c. wherein they are exceeding large, is seen. Hence also the _Vine_, if supported, will grow to a prodigious length. And _Hops_ and _Bryony_, are some of the tallest, amongst all _Annual Growths_: the _Aer-Vessels_ of all which, are very large. Whereas _Borage_, and many other like _Plants_, although the _Pores_ of their _Parenchyma_, are vastly wide, and filled with _Sap_; yet because their _Aer-Vessels_ are small, they are therefore but _Dwarf-Plants_. Wherefore the tallness or advancement of a _Plant_ or _Tree_, dependeth not upon the _Plenty_ of _Sap_, how great soever, but on the _Largeness_ of the _Aer-Vessels_.

3. §. AGAIN, as a _Plant_ or _Tree_ grows either _Shrubby_, or _Tall_ and _Entire_, according to the _Size_ of the said _Vessels_: so from their _Position_, doth it grow _Slender_ or _Thick_. So, where they keep more within the compass of a _Ring_, as in _Elm_, and _Ash_, the _Tree_, in proportion, usually grows taller, and less thick. But where the said _Vessels_ are spread more abroad, and especially are postured in _Rays_, as they are in _Oak_, the _Tree_ grows very thick. Because the said _Vessels_ thus standing all along nearer to the _Insertions_, there is a more ready and copious passage of the _Aer_ out of the one into the other; and so the _Diametral_ growth of the _Wood_ is more promoted.

4. §. LASTLY, from the same general cause it is, That the _Trunks_ of _Vegetables_ are either _Round_ or _Angular_. Those of all _Trees_ are _Round_. Because the _Barque_, being here thicker, and the _Aer-Vessels_ bound up with a greater quantity of _Wood_; the _Aer_ hath not sufficient power to move them, and the _Barque_ with them, into those various _Positions_ or _Figurations_, as the _Trunks_ of _Herbs_ do yield to.

5. §. Yet the cause of the various _shapes_ of the _Trunk_, is not the _Aer_ alone; but partly, the _Principles_ of the _Plants_ themselves, in conjunction therewith; according to the predominion whereof, and chiefly of some certain kind of _Salt_ or _Salts_, as I shall hereafter[63] more particularly explicate, the _Trunk_ is _Square_, _Triangular_, _Pentangular_, or otherwise _Figured_. And thus much in general of the _Figuration_ of _Trunks_.

[63] _B. 4. P. 1. Ch. 6._

CHAP. VI.

_Of the_ Motions _of_ Trunks.

THE _Motions_ also of _Trunks_ are various. Principally _Four_; _sc._ _Ascending_, _Descending_, _Horizontal_, and _Spiral_. The cause of the _Ascent_ of a _Plant_, is a certain _Magnetick Correspendence_ betwixt the _Aer_ and the _Aer-Vessels_ of a _Plant_; the _Motion_ and _Tendency_ whereof, the whole _Plant_ follows. This I have asserted, and I think, clearly demonstrated in my _First_ and _Second_ =Books= of the _Anatomy_ of _Plants_. I will here add this plain _Experiment_.

2. §. Take a Box of _Moulds_, with a hole bored in the bottom, wide enough to admit the _Stalk_ of a _Plant_, and set it upon stilts half a yard or more above ground. Then lodg in the _Mould_ some _Plant_, for Example a _Bean_, in such sort, that the _Root_ of the _Bean_ standing in the _Moulds_ may poynt upwards, the _Stalk_ towards the ground. As the _Plant_ grows, it will follow, that at length the _Stalk_ will rise upward, and the _Root_, on the contrary, arch it self downward. Which evidently shews, That it is not sufficient, that the _Root_ hath _Earth_ to shoot into, or that its _Motion_ is only an _Appetite_ of being therein lodged, which way soever that be: but that its nature is, though within the _Earth_ already, yet to change its _Position_, and to _move Downwards_. And so likewise of the _Trunk_, that it rises, when a _Seed_ sprouts, out of the Ground, not meerly because it hath an _Appetite_ of being in the open _Aer_; for in this Experiment it is so already; yet now makes a new _Motion_ upwards.

3. §. BUT although the _Natural Motion_ of the _Trunk_ be to _Ascend_; yet is it forced oftentimes to _Descend_. For the _Trunk-Roots_ growing out of some _Plants_ near the ground, and shrinking thereinto, like so many _Ropes_, do pluck the _Trunk_ annually lower and lower into the ground together with them; as may be seen in _Scrophularia_, _Jacobæa_, and many other _Plants_.

4. §. IF these _Trunk-Roots_ break out only about the _bottom_ of the _Trunk_, as in the aforesaid _Plants_, then the _Trunk_ gradually _Descends_ into the _Earth_, and is turned into a _Root_. But if it be very _slender_, and the _Trunk-Roots_ break forth _all along_ it, then it _Creeps_ horizontally; the said _Roots_ tethering it, as it trails along, to the ground; as _Strawberry_, _Cinquefoyl_, _Mint_, _Scordium_, &c.

5. §. AS to their _Spiral Motion_, it is to be noted; That the _Wood_ of all _Convolvulus_ or _Winders_, stands more close and round together in or near the Center, thereby making a round, and slender _Trunk_. To the end, it may be more tractable, to the power of the external _Motor_, what ever that be: and also more secure from breaking by its winding _Motion_.

6. §. Wherefore, _Convolvulus_ do not wind by any peculiar Nature or _Genius_, which other _Trunks_ have not; but because their _Parts_ are disposed so, as to render them more sequaceous to the external _Motor_. Even as the _Claspers_ of a _Vine_, having the like _Structure_, have also a _Motion_ of _Convolution_: whereas the _Branches_ themselves upon a contrary account, move in a _straight Line_.

7. §. The _Convolution_ of _Plants_, hath been observed only in those that Climb. But it seems probable, that many others do also _wind_; in which, the main _Stalk_, is as the _Axis_ to the _Branches_ round about. ♦ _B. 2. P. 1. Ch. 1._ ♦ Of which number, I conceive, are all those whose _Roots_ are twisted; a _Motion_ we observed in speaking of the _Root_. Whether it be so, or not the Experiment may easily be made by tying a _Thred_ upon any of the _Branches_; setting down the respect it then hath to any Quarter in the _Heavens_: for, if it shall appear in two or three Months, to have changed its Situation towards some other Quarter; it is a certain proof hereof. And that hereby the _Roots_ of many _Plants_ become twisted; the _Motion_ beginning in the _Stalk_, and ending at the bottom of the _Root_, which stands always fixed in the same place.

8. §. The _Convolution_ of _Trunks_, is made not _one_, but _divers_ ways; some moving by _South_ from _East_ to _West_; and others from _West_ to _East_. Wherefore it seemeth, that as the _Efficient Cause_ of _Convolution_, is not within the _Plant_, but external: so also, that it is not _One_, but that there are _Two Great Efficients_ of this _Motion_; _sc._ the _Sun_ and the _Moon_. Some winding together with the _Sun_, in its _Diurnal Motion_, (or, if the Earth moves, then, Inclining to the _Sun_) by _South_ from _East_ to _West_. And others winding with the _Moon_, in its _Monthly Motion_, from _West_ to _East_.

9. §. This possibly, may also be one _sensible_ way of distinguishing betwixt _Solar_, and _Lunar Plants_. Thus far, in general, of the _Motions_ of _Trunks_.

CHAP. VII.

_Of the_ Nature _of_ Timber _or_ Trunks, _as they serve for_ Mechanick Use.

THE last thing I purposed to speak of, is, Those several _Qualities_ of _Timber_ or of _Trunks_, by which they are fitted for _Mechanical Use_. As _Hardness_, _Softness_, _Fastness_, _Clevesomeness_, _Toughness_, _Brittleness_, _Durableness_, or any of the same _Qualities_ compounded. The _Visible Causes_ whereof are observable, _Partly_, in the _Structure_ of the several _Parts_; _sc._ the _Insertions_, _Sap-Vessels_ and _Aer-Vessels_; as to the _Number_, _Size_, or _Position_ of any of them. And _partly_, in the _Nature_ of the _Parts_; I mean such as is _manifest to sense_. According to our clear and distinct observing of all which Causes, we may understand, Wherefore any _Wood_ is made use of for any certain purpose. And also, wherein fitly to apply it to further _Use_. In order to which, a compleat History of the _Mechanical Uses_ of _Vegetables_ would very much conduce. I shall for the present give some _Instances_.

2. §. AS _First_, some _Woods_ are _soft_, as _Deal_, and _Sallow_. Yet from different Causes. _Deal_, from the great _Porosity_ of the _Wood_ it self, or the large _Pores_ amongst the _Sap-Vessels_. But _Sallow_, from the great number of _Aer-Vessels_ spread all over it. And therefore, though they are both _soft_, yet will not serve for the same purposes; _Sallow_ being well wrought upon, which way soever you cut it: but _Deal_, especially the white _Deal_, if it be cut cross, it tears, and will never polish or work smooth.

3. §. Again, in _Sallow_, by the equal spreading of the _Aer-Vessels_, the _Softness_ is equal or alike in all _Parts_. For which cause it maketh an excellent _Coal_ for _Painters Scribets_. Because it doth not only make a _light Stroak_, but every where _certain_; and so doth not disturb the even _Motion_ of the _Hand_. For the same cause, _Shoemakers_ also make use of it for their _Carving-boards_. Because being every where equally soft, it turns not the edge of their _Knives_, Which _Deal_ would presently do; because though very soft in some places, yet in others ’tis hard; that is to say, on the inner _Verge_ of every annual _Ring_ of _Wood_, where the old _Sap-Vessels_ grow much more compact and close together.

4. §. AGAIN, some _Woods_ are _soft_, but not _fast_; others are _both_, as _Linn_: its _Softness_, depending on the numerousness and equal spreading of the _Aer-Vessels_; its _Fastness_, on the closeness of the true _Wood_, and the shortness, and smallness of the _Insertions_. For which cause, it is of excellent use for many purposes; and particularly, for _small Sculpture_: such as may sometimes be seen for the Frames of _Looking-Glasses_, or of smaller _Pictures_ in _Water-Colours_.

5. §. SOME _Woods_, again, are _fast_, and _hard_, as _Elm_. Its _hardness_ depending upon the closeness of the _Wood_. Its _fastness_, _Partly_, upon the same cause; and _partly_, on the smalness of the _Insertions_; as also on the fewness of the _Aer-Vessels_ in proportion with the _Wood_; and on the _thwart_ and _cross Position_ of many of them. Hence it is, that _Elm_, of all others, is the most _Cross-grain’d Timber_; that is, cleaveth so unevenly, to and fro, according to the _cross Position_ of the said _Vessels_.

6. §. Hence also it cleaveth the _most Difficultly_. Even then, when it is without any _Knots_. For which reason it is always used, as best for the _Hub_ of a _great Wheel_. As also for _Water-Pipes_, and for _Pumps_. Not because it is the most _durable Wood_; but because it will not _split_ or _crack_, either in the _working_, or _afterwards_. For the very same reason, it is used for _Coffins_; that is, because, it will not _split_ in working: not because it will endure longest under ground; for _Pales_ are always made of _Oak_. So also the _Ladles_ and _Soles_ of a _Mill-wheel_ are always made of _Elm_; as also the _Keel_ of a _Boat_, _sc._ lest they should _split_: but the other _Parts_ are made of _Oak_.

7. §. It may here also be noted, That the _Planks_ commonly called _Groaning-Boards_, lately exposed, as a kind of _Prodigy_, to the view and hearing of many People, were of _Elm_. The _Aer-Vessels_ of this _Wood_, being, though not more numerous, yet more ample, than in any other _Timber_. So that upon the application of the _Red-hot-Iron_, as was usual, and thereby the _Rarifaction_ of the _Aer_ and _Watery Parts_ in the _Timber_; every _Vessel_ became, as it were a little _Wind-Pipe_ for their _Expiration_. And as a great many Drops falling together in a showr of Rain; so a great many of these _Pipes_ playing together, might make a kind of big or groaning noyse.

8. §. AS _Elm_, of all _Woods_, is one of the _fastest_; So, on the contrary, of all _hard Woods_, _Oak_ is the most _Cleavesome_, or _splitteth_ the most _easily_. The cause whereof is, _partly_, the _Largeness_ of the _Insertions_; and _partly_, the _Diametral_ or _Radiated Position_ of most of the _Aer-Vessels_: upon both which accounts, wherever a _crack_ is once begun, ’tis easily continued throughout the _Diameter_ of the _Trunk_.

9. §. AGAIN, some _Woods_ are _hard_, _fast_, and _tough_. So is _Ash_, and especially _Beech_. _Hard_ and _fast_, from some of the same Causes, as _Elm_. _Tough_ not from the _Structure_, but from the _Nature_ of the _Parts_; whose _Principles_ are united in a more exact proportion. Wherefore _London-Cars_ have the _Rings_ of their _Wheels_ of _Beech_; because it _tears_ more difficulty than even _Ash_ it self. Whence also for _large Screws_, there is no _Wood_ like it. But for _Small Screws_, of about an _Inch Diameter_, _Birch_ is the best; as being, though not so _hard_, yet more _tough_.

10. §. THE more _Brittle_ a _Wood_ is, ’tis likewise usually the more _durable_. So _Oak_, which, with respect to its _hardness_, is not a _tough_, but very _brittle Wood_, is almost as _durable_ as any. Whereas _Beech_, _Birch_, and the like, although very _tough_; yet for _Duration_, are of no service; for there are no _Woods_ will rot sooner: and therefore, though strong enough, yet unfit to make any _Standing Parts_ of _Building_, or of _Furniture_; especially in wet and moist places. Because, these _Woods_, having a less proportion of _Oyl_, than there is in _Oak_; they are apter to imbibe the moisture even of a _dank Aer_; by which moisture, they either _Rot_, or breed _Worms_, which destroy them.

11. §. HENCE it is, that what we call the _Heart_ of _Timber_, as it is more _brittle_, so also more _durable_; _sc._ Because more _Oylie_. So that which is called the _Sap_ of _Oak_, is much more _tough_ than the _Heart_, although the _Heart_ be more _durable_. That is to say, the older the _Wood_ is, the _Watery Parts_ are the more evapourated, whilst the _Oylie_ still remaine, as a kind of _Tincture_ or _Extract_ in the _Wood_. Even as we see, that the older _Seeds_ of any one _Kind_, are more _Oylie_ than those that are green and young. So that the _Oylie_ or _Rosinous Parts_ of the _Sap_, are a kind of _Embalming_ to the _Heart_, or older _Part_ of a _Tree_, securing it from the destructive impressions of the _Aer_. For which Cause it is, that _Oak_, _Yew_, _Cocus_, _Guajacum_, &c. which are _Oylie Woods_, have always much _Heart_, whereas _Birch_, _Alder_, _Beech_, _Maple_, which are very _Unoylie_, have never any _Heart_.

12. §. FROM hence likewise we may understand the Cause of the _Toughness_ of _Flax_: what we call _Flax_, being only the _Sap-Vessels_, or _Lignous Fibres_ of the _Barque_. And generally, the _Barque_ of any _Tree_, as of _Willow_ (whereof are usually made a sort of _Ropes_) is very _tough_. The _Vessels_ being here younger, and less _Oylie_ than in the _Wood_. So likewise _Hemp_, is nothing else but the _Sap-Vessels_ of the _Barque_ of the _Plant_ so called. And _Scotch-Cloath_, is only the _Housewifery_ of the same _Parts_ of the _Barque_ of _Nettle_.

13. §. WHENCE it is very probable, that there are many other _Plants_, as well as the above named, whereof might be made good _Tow_. And of some, especially in some respects, better than of _Flax_ it self. Because that even _Hemp_, although it will not make so fine a _Staple_, as _Flax_ (for all our fine _Hollands_ are made of _Flax_) yet _Flax_, which is but of the same fineness as _Hemp_, will never, by all the Art yet known, be made so white as _Hemp_ is made. The _Qualities_ therefore of the best _Tow_, that can be in Nature, are that the _Staple_ be _long_, _small_, _tough_, and _white_. So that if in the _Barque_ of any _Plant_, we can find these _Qualities_, or any of them, to excell; we may be sure, it will be of better use, in some respects, for the making of _Cloath_, or other purpose, than _Flax_ it self.

14. §. I WILL conclude with one _Instance_ more, and that is as to _Grafting_. The good and happy success whereof, doth certainly depend upon the suitableness or respondence betwixt the several _Parts_ of the _Stock_ and _Cyon_; as the _Barque_, _Wood_, and _Pith_; and that both as to the _Number_, _Size_, and _Position_ of the said _Parts_, and of their several _Pores_ or _Vessels_: according to the degrees whereof, the _Conjunction_ (_cæteris paribus_) will be more or less prosperous. So that of all such _Conjunctions_ as are found to be apt and taking, and which some have learned not without long Practice and Experience; another, only by comparing the _Branches_ of _Trees_ together, may with little trouble, and in much less time, inform himself. By the same means, some _Conjunctions_ which seem to be strange, as _Quince_ and _Pear_, _White Thorn_ and _Medlar_, &c. do yet, by the respondence of their _Parts_, as well as by _Experience_, appear to be good. And there is no doubt, but that many _Conjunctions_ not yet tryed, or not known to have been so, may upon the same ground, be tryed with good success.

15. §. The chief Use of _Grafting_ and _Inoculation_, is, That they _Accelerate_ the growth of _Good Fruit_. The _Cause_ whereof, is the _Knot_, which is always made in the _Conjunction_. By means of which, all the _Sap_ is strained, and so ascendeth up into the _Graff_ or _Bud_, both _Purer_ and in less _Quantity_; and is therefore better and sooner concocted. Hence, the smaller the _Fruit_ of any _Tree_, though it be not the best, yet the _Sap_ being there, in _less Quantity_, is the _sooner ripe_. On the contrary, where the _Sap_ ascendeth too freely, it doth not only _retard_ the growth of the _Fruit_, but produceth _Barrenness_; as is seen in those _luxuriant Branches_, where it runs all up to _Leaves_. Hence also _Vines_, by _Bleeding_, become more _Fruitful_: that is, by the Effusion of _Part_ of the _Sap_, there is a more easier _melioration_ of that which remains. Even as _Phlebotomy_ doth oftentimes produce a more healthful and better _Habit_ of our own _Bodies_. To conclude, the _lessening_ the _Quantity_, and thereby the _melioriation_ of the ascending _Sap_, by _Knots_, is _Natures_ own contrivance; as is seen in _Sugar-Cane_, _Corn_, and other _Plants_.

THE

ANATOMY

OF

LEAVES, FLOWERS, FRUITS and SEEDS.

In Four Parts.

The FOURTH BOOK.

By _NEHEMJAH GREW_ M.D. Fellow of the _ROYAL SOCIETY_, and of the _COLLEGE_ of _PHYSICIANS_.

_LONDON_, Printed by _W. Rawlins_, 1682.

THE

CONTENTS

OF THE

First Part.

CHAP. I.

_Of the_ Protections _and_ Folds _of_ Leaves.

CHAP. II.

_Of those Things which appear upon the_ Surface _of the_ Leaf.

CHAP. III.

_Of the_ Figures _of_ Leaves; _and the Apparent_ Position _of the_ Fibres.

CHAP. IV.

_Of the_ Parts _and_ Texture _of the_ Leaf.

CHAP. V.

_Of the_ Duration _of_ Leaves, _and the_ Time _of their_ Generation.

CHAP. VI.

_Of the_ Manner _of the_ Generation _of the_ Leaf. _Where also, that of the_ Two General Parts _of a_ Plant, _sc. the_ Lignous _and_ Parenchymous, _is further explain’d._

To the Honourable

Robert Boyle Esq;

SIR,

_AFTER I had finished the foregoing_ Books, _In which, I conceive, as far as_ Glasses _will yet lead us, I have clearly Describ’d and Delineated the_ Structure _of a_ Plant; _and have endeavour’d, in some part, to Unfold the_ Reason _and_ Scope _of_ Nature _therein: I was willing to sit down, and leave what remained, to the_ Improvements _of the Present and Succeeding_ Ages.

_But in Discourse upon this Subject,_ You _have been pleased frequently to insist, That I should by no means omit, to give likewise, some Examples of the_ Mechanisme _of_ Nature _in all the other_ Parts. _The Performance whereof therefore, next to the_ Obedience _I owe to the_ Royal Society, _is to be looked upon, as a Due to the Authority which Your Judgment hath over me._

_This I have said, that, if what is herein done, shall prove acceptable unto_ Learned Men; _they may know, To whom they are once more to give their Thanks: After they have so often done it, upon (a better score) the Publishing of Your own Excellent Works. In which, there seems to be a Question, Whether Your Continual Endeavours, to enlarge the Bounds of_ Natural Knowledge, _or Your Successes therein, have been the Greater. So that, whereas_ Nobility _in some, doth only serve to lift them, like_ Jupiter’s Satellits, _out of sight:_ You, _by giving a greater Light, have drawn all Mens Eyes upon_ You. _And whilest there are many, in all_ Ages, _fond of Preheminency in the Conduct of_ Popular Affairs; _who yet rarely hit the Mark they aim at; or aim at That they pretend:_ You _have thought fit, rather to separate_ Your Self, _to that more Innocent, and more Noble Sort of_ Wisdom, _which lieth, not in the_ Arts _of_ Conceiling, _but in_ Discovering, _the Truth of Things._

_That we may have many to imitate_ You _herein, cannot but be heartily wish’d by all, who regard the Honour of their own Country; as it is, with much Zeal, by_

Sir,

Your most obedient

Servant

_NEHEMJAH GREW_.

THE

ANATOMY

OF

LEAVES,

PROSECUTED

With the bare EYE,

And with the

MICROSCOPE.

Read before the _Royal Society_, _Octob. 26. 1676_.