caufe fome parts of its Sulphur, Saltpetre, &c. are ftrongly agitated, and that this agitation gives them the virtue to light and warm us; fo the Flame of a Taper is nothing but lighted fmoak, and this fmoak is compofed of the fame Principles which are in the Wax: Whence it is evident that Fire ought not to be taken for a Principle.

In relation to the Air, there is always fome of it in the Water, and confequently in the Juice of Plants, which we easily discover in the effervefcencies of diftilled Liquors.

PART I.

Of the Vegetation of Plants.

THESE different Principles of Plants being fufficiently established by what has been faid above, it is time, Sir, that I explain to you after what manner Plants are nourished, and how their Vegetation is performed.

I begin with the firft Germination of the Seed, of which I have made feveral Obfervations. I put in Summer time fome of those white Beans which we call Phafeoles, to foak in Water at that end which is fartheft from the little Germ that is between the two Lobes which compofe the Body of the Bean. This little Germ is compofed of two or three Leaves extremely small, folded one upon another, which forms a little Stalk the extremity of which terminates in a Point. In the middle of this Stalk are two little Canals or Pipes fixed to the two Lobes, and each of them performs the fame office for the

nourish

nourishment of the Plant, as the umbilical Veffels for the nourishment of Animals; for thofe Lobes having imbibed the Water like a Spunge, the little Germ fucks it in through these small Canals, and along with it fome Particles of the Matter of these Lobes, and in a few Days the Leaves unfold and fhoot out in length and breadth, and the little Point which is to extend it felf into Root, begins to defcend towards the Water, though at the beginning it is fometimes turned upwards, but it bends it felf by little and little to come thither.

We fee the fame thing in the Seeds of Gourds or Cucumbers, Melons, &c. and consequently the first beginning of Vegetation proceeds from the Seed after its imbibition of the Water: I alfo obferved that the little Leaves open, as they grow, the Lobes of the Bean, and extend themfelves above an Inch in length with an extreme green colour, before the Root, which continues white, has reached the Water; but as foon as the Point of the Root has gained the Water, it fucks it up, and tranfmits it not only into the Stalk and Leaves, but alfo into the two Lobes through their little Canals, and thefe two Lobes grow afterwards in length and breadth, and in the Seeds of Gourds and Pompions they grow very much, and change themfelves into two large green Leaves, which continue to furnish the Plant through the fame little Canals their fat and oily Subftance, mixed with the Juice. which they draw from the Root, to fortify the little Plant which does as yet receive from the Earth alone a Juice fufficiently prepared. This Body of the Seed is alfo analogous to the yolk of an Egg, which ferves a long while for the

nourish

nourishment of young Birds, even after they have broken the Shell.

The better to comprehend the Effects caufed in these Lobes, we may compare them to what we obferve in the Liver of Animals, where a great many capillary Veffels terminate in various Trunks, fome pour out the Blood into the Liver, and others carry it back again into the Trunk of the Vena Cava; fo there are a great many capillary Veffels in the Lobes of Gourds, and other fuch like Seeds, fome of which distribute into these Lobes the Juice which comes from the Root; and others carry from these Lobes the first well prepared Juice to the Plant, and continue fo to do till the Plant be well fortified.

Pease, and almost all forts of Beans, Acorns, Peach and Apricock Kernels, do not caft forth the Body of their Grains, but it remains in the Earth, and mingles it felf with the moisture it there finds to nourish the young Plants: But the greater part of fmall Herbs, as well as Gourds and Melons, push out of the Earth the two Lobes in two Leaves, and we generally fee the Foldings of the Lobes appear at the extremity of the Leaves.

We may obferve the like beginning of Vegetation of Shrubs which come up from Slips, or Scyons, as thofe of the Vine, the Elder, Goofeberries; for the Branch which we cut off at both ends in form of a Wedge being put half way into the Earth, the Pith which is very grofs in proportion to that of other Shrubs, imbibes like a Spunge the Rain Water, or that which is in the Earth, and tranfmits it into the small Fibres which are between the Rind and the Wood, whence it is partly pushed towards the lower

end,

end, to produce Roots at the extremity of the little Point, and about the Knots which are hidden in the Earth, and partly towards the Knots which are in the Air, to make the Buds that are there fwell and plump up, and to make them fhoot out into Branches and Leaves. The Canals or Pores which are in this Pith, do not extend themselves long ways according to the Stalk of the Tree, but are diftinguished into a great many little oval Cells, which bear fome refemblance with the Honey-Comb, which appears when the Stalk is fplit or cleft down long ways, and when we examine one half by the affiftance of a Microscope.

Now to know after what manner thefe little capillary Veffels, which are in the Grains, imbibe this Juice, as alfo how the Roots receive the Rain Water, we must consider what happens in the Vegetation of Animals, which evidently has fome analogy with that of Plants.

We know that the Matter which nourishes Animals, after having been prepared by the Stomach, paffes into the Guts, where it finds little Pores and imperceptible Conduits, through which the most fubtle Parts of this Matter, which we call Chyle, pafs and intoduce themselves; and thefe Conduits are apparently difpofed in fuch fort, that whatever enters therein are hindered from returning, of which we fee Examples enough in feveral other parts of the Body; and even in the Veins where there are pellicules or little stretched out-skins, which we call valvules, that are fo difpofed as to let the Blood pafs which goes to the Heart, but oppofe and obftruct its return.

Now according to this analogy of the Vegetation of Animals and Plants, it is probable that

the

the Rain Water mixed with the other Principles which compofe Plants, being joined and contiguous to their Roots, finds there imperceptible Pores through which it infinuates it felf, and its return is obftructed, which is the cause that this firft Sap is preffed always on in Plants.

It has fome refemblance with the Chyle, and becomes analogous with the Blood of the Veins, in proportion as it mingles with the best prepared Juice that is already there, and which is almost like that which the Body of the Seed gives in the beginning.

This first entrance of the Water into the Roots is caused by a Law of like nature with the motion of union, of which I have spoken elfewhere; for where-ever there are very ftrait and narrow Tubes which touch the Water, it enters therein and rifes alfo against its natural inclination to defcend.

For an Example of this, take a very narrow Tube of Glass, and very clean, put one of the ends of it into Water, it will rife to a confiderable height above its level; put one end of a Sugar Loaf into a little Water, it will rife up to the top in a little time; but it will not rife in Glass Tubes rubbed with Tallow, or if through time they have acquired a certain foulness, as is that of Varnish to which Water will not stick a for it is not enough that the Pores are difpofed to let the fubtile Parts of other Bodies enter, they must also be pushed thither by fome Principle of Motion: But whatever be the Cause of the Effect, vulgarly called Attraction, it is enough that it is very common, and that Chymistry furnishes us with a great many Examples

of it.

MARCH 1731.

M

The