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Show SA SA ticularlyin fuch as abound with Sapyas the Great unfolded the Leaves, thefe come to ferve as Lungs for the Circulation, and furth er P T eparation of the Juice. Se Tithymale, Milk-thiftie, &c, if the Ligature be faftened tight round the Stem, the Part above it is found to {well very confiderably, and that belowit a little, whence it appears, that there isa Juice afcending from the Root, and likewife another defcending from the Branches; and that the latter is thicker than the former, which quadrates exactly with the common Syftem; the Juice being fuppos’d to arife in capillary Veffels, in form of a fubtil Vapour, which condenfed in the Extreams of the Plant by the Neighbourhood of the cold Air, turns back in form of a Liquor, through the more patent Pipesofthe inner Bark. M. Dodart, inftead of the fame Juices gond returning, contends for two feveral Juices; the one imbibed from the Soil, digefted in the Root, and from thence tranf mitted to the Extreams of the Branches, for the nourifhing of the Plant; the other received from the Moifture of the Air, entring in at the Extremities of the Branches; fo that the afcending and defcending Juices are not the fame. For thefe tender Leaves being expos'd to the alternate Action of Heat and Cold, moift Nights, and hot {corching Days, are alter. nately expanded and contraéted, and the more on Account of their reticular Texture. By fuch Means is the Juice ftill further altered and digefted, as it is further in the Petala or Leaves of the Flowers, which tran. mt the Juice, now brought toa furth er Subtilty, to the Stamina: ‘Thef communicat e it to the Farina, or Dutt in the Apives, which is, as it were, the Male Seed of the Plant, where having undergone a further Mazturation, it is hed into the Pifii, which performs the Office of an Uterus or Womb, and thus having acquir'd its laft Perfeétion, it gives Rife toa new Fruit or Plant. The Root or Part whereby Vegetables are connected to their Matrix, and by which they receive their nutritious Juice, confifts of an infinite Number of Va/a abforbentia, which being difpers’d through the tices of the Oneofhis chief Arguments is, That if two Earth, attract or imbibe theInterf Juices of the Trees of the fame Kind be tranfplanted in one Day, after firft cutting of their Roots and Branches, and if after they have taken Root again, fome of the newShoots put forth each Year be cut offone of them, it will not thrive half fo well, notwithftanding itsRoot and Trunk fame ; confequently, every Thing in the Earth that is diffoluble in Water, is liable to be im= bib’d ; as Air, Salt, Oil, Fumes of Minerals, Metal, €&c. and ofthefé do Plants really confift. Thefe Juices are drawn from the Earth very crude, but by the Stru@ture and Fabrick This he conceives to be a Proof of the of the Plant, and the various Veftels theyare Plant's deriving Nourifhment bythe Branches, ftrai ned through, become changed, further and concludes being entire, as the other. it to be ofan aerial Nature, becaufe form’d of the Moifture of the Air, Dew, &c. whereas that imbib’d from the Soil is terreftrial, €c. Hift. de P Acad. Roy. Ann. 1709. The Humour orSzp of a Plant, then, isa Juice, furnifh’d by the Earth, and changed into the Plant, confitting of fome foffil Parts, other Parts derived from the Air and Rain, and others from putrefied Animals, Plants, €c. confequently in Vegetables are contain’d all Kinds of Salts, Oil, Water, Earth, &e, and, probably, all Kinds of Metals too, inaf. muchas the Afhes of Vegetables always yield fomewhat which the Loadftone attraéts. This Juice enters the Plant in form of a fine and fubtil Water ; which the nearer it is to the Root, the more it retains of its proper Nature ; and the farther from the Root the more Aétion it has fuftain’d, and the nearer it approaches to the Nature of the Vegetable. Confequently, when the Juice enters the Root, the Bark whereof is furnifhed with excretory Veflels, fitted to difcharge the excremMentitious Part, it is earthy, watry, acid, andfcarce oleaginous at all. poor, In the Trunk and Branches it is further Prepared, though it ftill continues acid 3 as we fee by tapping or perforating of a Tree in the Month of Febr; whenit diftils a watry Juice apparently acid, The Juice being here carr ied to the Germs or Buds, is more concocte d ; and here having elaborated, fecreted, and affimilated to the Subftance of the Plant. The Motion of the nutritious Juices of Vegetables is produc’d muchlike that of the Blood in Animals, by the Action of the Air; in effect, there is fomething equivalent to Re- {piration throughout the whole Plant. The Difcovery ofthis is owing to the admirable Malpighi, who firft obferv’d, that Vegetables confift of two Series, or Orders of Veffels, 1. Such as receive and convey the alimental Juices, anfwering to the Arteries, Lacteals, Veins, &c. of Animals. 2. Trachee or Air-Veffels, which are long hollow Pipes, wherein Air is continually re- ceiv'd and expell’d, 7. ¢. infpired and expired; within which Trachea, he thewsall the former Series of Veffels are contained. Hence it follows, that the Heat of a Year nay, of a Day, of a fingle Hour or Minute, muft have an Effect on the Air included in thefe Trachea, i. e. mult rarefy it, and conic quently dilate the Zrachee, whence arifes 4 perpetual Spring or Source of Aétion, to pto- mote the Circul ition in Plants. : For by the Expanfion of the Trachea, ae Veffels containing the Juices are preffed, pd by that Means the Juice contained is ae nually propell’d, and {fo accelerate d; bywh ae Propulfion the Juice is continually comm nuted, and render’d more and more {ubtil, and fo enabled to enter Veffels ftill incr and finer, the thickeft Part of it being at the S A Time fecreted and depofited into the lateral Cells or Loculi of the Bark, to defend the Plant from Cold, and other external Injuries. The Juice having thus goneits Stage, from the Root to the remote Branches, and even the Flower ; and having in every Part ofits Progrefs depofited fomething both for Aliment and Defence, what is redundant paffes out into the Bark, the Veffels whereof are inofculated with thofe wherein the Sap mounted, and through thefe it re-defcends to the Root, SA 1. The firft Clafs comprehends the crude; nutritious Fuice, or the Juices of the Roor and Stem of Plants, which arelittle more than the mere Matter of the Element, as drawn by the Root from the Body it adheres to, whether it be Earth, Water, orthelike. This Juice is found in every Part of the Plant, and therefore may be held an wnive Juice 5 yet he confidersit as the Juice of r/at the Root and Stem, becaufe it is chieflyfoun d in them. and thence to the Earth again; and thus a This he takes to bea fubacid watery Lymph , Circulationis effected, without anyfpecifick Tafte or Smell, as not Thus is every Vegetable acted on by Heat being yet arriv’d to the Maturity of Oiline fs. and Cold, during the Day-time efpecially, Tothis Clafs belong thofe Juices which diwhile the Sun’s Force is confiderable, the Sap ftil in great abundance from Wounds or InVeffels fqueez’d and prefs’d, and the Szp pro= cifions made in the woody Parts of Plants ; traded and raifed, and at length evacuated, fuch, e. ¢. is that tart Liquor oozing from the and the Veffels exhaufted ; and in the Night Root of the Walnut-tree, when cut off in the again, the fame Zrachee being contracted by Month of May. the Cold of the Air, the other Veffels are Such alfo is that limpid, fabacid Humour, easd and relax’d, and fo difpos’d to receive flowing out veryplentifully at an Incifion in the freth Food for the next Day’s Digeftion and Birch-tree in the Month of March, to the Excretion. Quantity of feveral Gallons in a few Days. What Courfe the Juice takes after it is imSuch alfo is the Juice iffuing out of the Vine, bibed by the Roots, isnot very clear, the Vef= wounded in the Spring-time, which always fels that take it up to convey it to the Plant taftes tartifh, and ferments like the Grapes are too fine to be traced; and hence it has themfelves. been controverted, whetherit is by the Bark This Juice may be efteem’d as yet foffil, or the Pith, or the woody Part, that the Plant being generated of and in the Earth ; for the is fed. Juice of the Earth being receiv’d into the The more commonOpinionis for the Bark; Canals of this Plant, retains its Nature during the Juice raifed by the Capillaries of the two or three Circulations, nor docs immed iWood is here fuppofed to defcend by the ately commence a vegetable Juice. larger Fibres, placed in the inmoft Part This Clafs of Juices therefore he accounts thereof, immediately over the Wood ; in as the Chyle of the Plant, being chiefly foundin which Defcent the Szp, now fufficiently the firft Order of Veffels, viz. in the Roots prepared, adds a Part of its Subftance to and the Body of the Plant, which anfwer to the contiguous Wood, and thus increafes the Stomach and Inteftines of Animals. by Appofition, And hence it may be, that 2. The fecond Clafs of the Fuices is that of hollow, carious, or rotten Trees, which the Leaves, which are the real Lungs of Plants , have neither Pith nor Wood, except juft and accordingly make a further Change of the enough to fuftain the Bark, do grow and Juice, which they receive from the Roots and bear. Stem by Force of the Air. ~The Juice of Some contend for the Wood, which they Leaves is different therefore from the firft obférve to confit of flender, capillary ‘Tubes Juice, as being more fulphureous and farther Tunning parallel to each other from the Root elaborated ; not that it derives any Sulphur up the Trunk, being properto receive in a fine from the Sun, but that its watery Part exhaling, Vapour ; in the Afcent whereof the Fibres it becomes moreoily and lef volatile. become opened, and their Subftance increafed: The Juice of Leaves he diftinguifhes into And thus the Trunks of Trees are {aid to in- three Kinds : creafe in their Circumference The firft is the mwtritious Fuice of the As for the Pith, as the woody Subftance of Leaves ; which is that already defcrib’d, only the Trunk becomes more w oody, the Pith is comprefs'd and ftraightned to fuch a Degree, that in fome Treesit quite difappears ; whence it feems, that its Office in Vegetation is not Very important, fince its Ufe is not perpetual. By its {pongeous Subftance, it fhould feem fitted to receive any fuperfluous Moifture tranfuding through the Pores of the woody Fibres: And if by the Excefs of fuch Moiiture, or the like Caufé, it corrupt and rot, as it frequently happens in Elms, the Tree does not growthe worfe for it, which is a convin- Cing Proof it is of no great Ufe. farther elaborated in the minute Veficule of the Leaves, and confequently lefs and watery, and more oily and faccharine. The fecond is Wax, which exfuding out of the Leaves, adheres to the Surface, and is {crap'd off by Bees withtheir rough Thighs to build their Combs withal. ‘This is chiefly afforded by Lavender and Rofemary : Upon the latter of which the Wax maybe plainly perceiv’d fticking to the Leavesof it 5 The third is Man 2; not that with which the Iraelites were fed in the Defart, but a Drug fold amongus: It is an effential faccharine Salt, exfuding chiefly by Night, and in The Learned Dr. Boerhaave diftributes the Juices of Plants into fix Claffes : the Summer Seaton, from the Leaves of a fort of |