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Show AN Wood, which maybe diftinguifh’d from the former Circles of the Root, Stock or Trunk; and if they are cut horizontally, will fhew the Number of fuch Circles and fo how many Years the Tree is old. And this fucceffive Mutation of the into Liber, and of Liber, into Wood, is like to that we obferve in the human Bodyin the beginning of a Callus; for a Call confifts of Skin, but fo comprefs’d, that all the Veffels are loft, and that Skin being become {folid, is increas'd and grows to a greater Bulk. But befides thefe hitherto defcrib’d, there occurcertain peculiar Veflels (of which Mention has been made in deferibing the Cortex) whichare foundfull of Turpentine, Gum, or a certain concreted Juice proper to them, the conftant Progrefs of which is not very confpicuous in all of them, byreafon of the Tranf- parency of the Moifture. 5. The fifth and laft Part is the ft inward ; the Medulla or Pith, difpos’d in the middle Center of the Root; and as it feems different from the former, feeing this is fometimes wat and that never, this appears Marrow of an Animal: As for its Subftance, tions of their Veffel > took a young Oak-Branch 7 Inches Diameter, at its tranf. I full of Leaves; verfe Cut, 6 Foot high and it confifts of little tranfparent Globules, chain’d or link’d together, fomewhat like the Bubbles and having cut a large Gap to the Pith » Inches Some iuppofe, that the Circulation of the Sap is effected by means of the Pith, others by the Bark, and others by the /Vood. oY in his Book De motu A lium, fuppofes the tender growing Shoot to bedi tended like foft Wax, by the Expanfion of the Moifture in the {pongy Pith, which di- from the Bottom, andof an equal Dept! whole Length, and < cut another Gap 4 Inches above that on the oppofite Side; he fet the End of the Stem in Water, and that in two Nights and two Days time it imbib’d and perfpir'd 3 Ounces ; while another like Oak-Br but than that, i Stem, im From this, and r he there ) that bi mentions, he other Experiments j ve a mott free ap- Veffels, thofe great Quantities o Liquor having pafs'dlaterally by the Gaps, in that, byfeveral Experiments, on Cylinders of Wood, little evaporated by the Gaps. i lating Moifture, he concludes, is hinder’d from returning back, while it expands by the Sponginefs of the Pith without the Help of ny lateral Communicati is the exterior Part of Trees, ferving them fo generally ofa ff that compofe the Froth of Liquor. Skin or Co P : And the Reverend Mr. Hales is of Opinion, indeed, that “tis very probable, that the Particles of Water that immediately adhere to, andare {trongly imbib’d into and attracted by every Fibre of the fpongy Pith, will fuffer fome Degree of Expanfion before they can be detach’d by the Warmthofthe Sun from each attracting Fibre, and confequently the Mafs of Fibres, of which the Pith confifts, muft efore be extended. 1 that the Pith maybe the more fervicePurpofe, Nature has provided in more fungous, that more durable. PBR ITLL As to the manner of the Root’s performing its Function, it may be obferv’d, that the Root hay imibib’d the jaline and aqueous Juices of the Earth, and faturated itfelf with them, for the Nourifhment ofthe Tree, thofe Juices are put into Motion by Heat ; which having enter’d the Mouthsofthe arterial Vef- fels from the Root, they mount to the 'Top with a Force anfwerable to what fers them in Motion; and by s Means they gradually open the minute Veffels roll’d up, and expand them into Leaves. 2. The Wocd: This is confider’d as con- fifting of capiliary Tubes, running parrallel from the Root throug capillary rifes 1 Tul from the Apertures of erial Veffels, becaute the Sap Root through thefe. The thefe Tubes are, for the moft part, too minute to be Eye, unlefs in aC perceiv’d by the bare arcoal, Cane, or Wood, fays Dr 1, by microfcopical Obfervations, af s to be only an Affemblage of infinitely minute Canals or hollow Fibres ; fome of which arife from the Root upwards, and are difpos’d in Form of a Circle ; and the others, which are call’d Jnfertions, tend horizontally from the Surface totl Center, fo that they crof$ each other, and are interwoven like the Threads of a Weaver’s Web. Befides the cay 'y Tubes, &c. before- mention’d, there are other larger Veffels which fome call venal Veffels, which are dife pos'd on the Outfide of the arterial Veffels. between the Woodand the inner Bark, andlead down to the Covering of the inward Root: Thefe Veffels z fuppos’d to contain the liquid Sap found in Plants in the Spring, €c. The Reverend Mr. H. cellent Treatife of Vegetable Staticks, that in order to find whether there was any lateral Communication of the Sap and Sap-V effels, as there is of the Blood in Animals, by Means which the Wood confifts; fo that having imbib’d the proper Tree, it is carry’d up by th thro’ the fine arterial Ve Top of it; and be Cold, it does, by bythe Veffels, w the inner ots a {trong Partition at every Knot, artitions ferve not only as Plinths or ( irments for the dilating Pith to exert its but alfo to prevent thetoo free refy’d Sap fromthe Pith. ongy Subftance by equally ; Way, would not pro» but rather a globofe to prevent which Incon» that Nature has pr agms,. befides thofe at ich are placed at {mall Diftan- ice of Veins; and as it paffes by, leaves {uch Parts of its Juice as the Textu will receive, and requires for its Support. Some are of Opinion, that that foft, whitith Rind or Subftance which lies between tt inner Bark and the Wood, does the O Veins: And fome call this a third B, fuppofe it to differ fro he other, that the Fibres of it are clofer ; is that which contains the liquid S: €c. which are foundin the Plants int and Summer Months, which hardens by degrees by means of the Sapit tranfimits, and is imperceptibly convey’dinto the ody Part of the Tree. The Bark ferves for divers Purpofes ; for it not only tran{mits the nutritious Juices of the Plants, but alfo contains divers fat oily Humonrs, to defend the inner Parts from the Injuries of the Weather. As Animals are furnifh’d with a Panniculus Adipofus, ufeally replete with Fat, w invefts and covers all the fiefhy Parts, and fercens them from external Cold; fo are Plants encompais'd with a Bark, replete with fat Juices, by means whereof the Coldis kept out, and in Winter-time, the Spicule of Ice prevented from fixing and freezing the Juices in their Veflels; whence it is, that fome Sorts of Trees remain ever- ), thereby preventing its too tion. y plain to be feen, in the unut-tree, and the fame may Tree or Plant, anfwering to the Medui/a ot Marrow ances throughout the whole Length of the as fo many jointly acting Powers, placed at different Stations, thereby with more Eafe, to draw Plenty of Sap to the extending Shoot. the moretender Part ofa Plant remarkable its Colour or Form, or both, cohering with the Rudiment of the Fruit, and. contains the Organs of Generation ; fome of thefe Flowers contain the Male Organs, asthe Stamina and Apices, which are loaded with the a Fees s, which, when ripe, is {catter’d into thofe Flowers, which are Female, and confift only of an Ovarinm, which furrounded with the Petals; other there are which have both Sexes contain’din in the Pith of the Branches of the fame Flower; thefe are called Herma dite Flowers. e not to be diftinA Fruit, Kapaes, is not that part of a Plant while the P:th is full and replete with which is eatable, but rather, the Seeds with > yet when it dries up, theyare often their Covering fhould be called the Fruit. This 2 feen: Andit is farther to be Covering cherifhes the Seeds until they come where the Pith confifts of to Maturity, fo defend it from the Injus, the Fibres of tho ries of the Weather, as.that they are not hurt n fot to run horizontally, whereby thereby, and alfo prepare the Juices defign’d y can the better refift the too great lateral for their Nourifhment, ‘that it may, with Dilatation oftheSi : enter their {mall Bodies in a juft Proand Branches of a Tree bear portion lance to the exterior Members and The Motion of the nutritious Juices of Limbs of an Animal, which it may fubfift ithout, tho’ the Rotting and Morti ; n do oftentimes occafion a total De- yn ofit. Accordinglythe li eects are from the wounding or lopping of a from the wounding orcutting off a an Extravafation, Callus, or the is Part of a Plant extended into green throughout the Year, by reafon their Barks are more compact, and contain a larger Quantity of Oil than can be {pent and exhal’d bythe Sun The Pith is the inward central Part ofa not much unlike a pulmonary 7 inftead of Lungs to the PI ration and Refpiration are ch thereby. In the Day-time, hath rarefy’d the mounting Jui es, fo as to become fpecifically lighter than the Air, they flow out thro’ the Pores of the Leaves, and do evaporate, which is the Occafion of the Leaves becoming fo flaccid in very hot Weather; but in the Night, when, by the C the Juices are more condens’d, then the Leaves are erected again, and do drawin a great Share of Nourifhment from the Air. Thefe Leaves we may ob e to be of different Textures on each Side, the upper Surface being, for the moft part, {mooth, the better to fhoot redundant Moifture, while the under Surface is, many times, of a rough and tony Texture, by which it is capable of taining the Moifture; for which Reafon we find, if by ill M ment, ; Shoots of Trees are fo nail’d to a Wall, &c. as to m the Surfaces of the Leaves the wrong Side ds, the Shoot is at a Stand until the s have obtain’d their proper Difpofition. s, as the learned Mr. Hales ob{tributed at {mall Dif- h and Breadth, in fuch a manneras to ave one Side difti The Leaves, a fhable from the other. ing to Malpighius, con- fift of {6 many interwoven Utricles, as to be Plants is produc’d much like that of the Blood in Animals, by the Aétion of the Air, and, in effect, there feems to be fomething equivalent to Refpiration throughout the whole Plant. us was the firft who obferved, that Vegetables confifted of two Series, or Orders of Veffels. é ich have been treated of beand conveythe alimental d whict wer to the Arteries, lac- s, Veins, &c, of Animals: And, 2, The |
