The Sap being thus prepared in the Lobes of the Bean, ’tis thence discharg’d; and either into the Plume or the Radicle, must forthwith issue. And since the Plume is a dependent on the Radicle; the Sap therefore ought first to be dispenced to this; which accordingly is ever found to shoot forth before the Plume, and that sometimes an inch or two in length. Now because the primitive course of the Sap into the Radicle, is thus requisite, therefore by the frame of the Parts of the Bean is it made necessary too. For we may observe that the two main Branches of the Seminal Root in which the several Ramifications in either Lobe are all united, commit not themselves into the Seminal Trunk of the Plume, nor yet so as to stand at right Angles with them, and with equal respect towards them both; but being producted through part of the Parenchyma of the Radicle, are at last united therein to the main Trunk, and make acute Angles therewith; as may be seen by [Fig. 2]. Now the Sap being brought as far as the Seminal Root in either Lobe, and according to the conduct thereof continuing still to move, it must needs immediately issue into the same part whereinto the main Branches themselves do, that is, into the Radicle. By which Sap, thus bringing the several Tinctures of the parts aforesaid with it, being now fed; it is no longer a meer Radicle, but is made also Seminal, and so becomes a perfect Root.
The Radicle being thus impregnate and shot into a root, ’tis now time for the Plume to rouze out of its Cloysters, and germinate too: In order whereto, ’tis now fed from the Root with laudable and sufficient Aliment. For as the Supplies and motion of the Sap were first made from the Lobes towards the Root, so the Root being well shot into the Moulds, and now receiving a new and more copious Sap from these; the motion hereof must needs be stronger, and by degrees revert the primitive Sap, and so move in a contrary course, sc. from the Root towards the Plume; and, by the continuation of the Seminal trunk, is directly conducted thereinto; by which, being fed, it gradually enlarges and displayes it self.
The course of the Sap thus turned, it issues, I say, in a direct Line from the Root into the Plume, but collaterally into the Lobes also; sc. by those two aforesaid Branches which are obliquely transmitted from the Radicle into either Lobe. By which Branches the said Sap being disbursed back into all the Seminal Root, and from thence likewise into the Parenchyma of the Lobes; they are both thus fed, and for some time augmenting themselves, really grow; as in Lupines is evident.
Yet is not this common to all Seeds; some rot under-ground, as Corn; being of a laxer and less Oleous substance, differing herein from most other Seeds; and being not divided into Lobes, but one entire thick Body. And some, although they continue firm, yet rise not as the great Garden-Bean; in which therefore it is observable, that the two Main Branches of the Lobes in comparison with that which runs into the Plume, are but mean; and so insufficient to the feeding and vegetation of the Lobes; the Plume, on the contrary, growing so lusty, as to mount up without them.
Excepting a few of these two kinds, all other Seeds whatsoever, (which I have observed) besides that they continue firm, upon the Vegetation of the Plume, mount also upwards, and advance above the Mould together with it; as all Seeds which spring up with dissimilar Leaves, the two (for the most part two) dissimilar Leaves, being the very Lobes of the Seed divided, expanded, and thus advanced.
The Impediments of our apprehension hereof are the Colour, Size and Shape of the dissimilar Leaves. Notwithstanding, that they are nothing else but the main body of the Seed, how I came first to phansie, and afterwards to know it, was thus: First, I observed in general that the dissimilar Leaves were never jagg’d, but even edg’d: And seeing the even verges of the Lobes of the Seed hereto respondent, I was apt to think, that those which were so like, might prove the same. Next descending to particular Seeds, I observed first of the Lupine; that as to its Colour, upon its advance above the Mould, it ever changed into a perfect Green. And why might not the same by parity of Reason be inferr’d of other Seeds? That, as to its size, it grew but little bigger than when first set. Whence, as I discern’d (the Augmentation being but little) we here had only the two Lobes: So, (as some augmentation there was) I inferr’d the like might be, and that, in farther degrees, in other Seeds.
Next, of the Cucumber-seed. That, as to its Colour, often appearing above ground in its Primitive white, from white it turns to yellow, and from yellow to green, the proper colour of a Leaf: That, as to its size, though at its first arise, the Lobes were little bigger than upon setting; yet afterwards as they chang’d their Colour, so their Dimensions also, growing to a three-four-five-fold amplitude above their primitive size: But whereas the Lobes of the Seed are in proportion, narrow, short and thick, how then come the dissimilar Leaves to be so exceeding broad, or long and thin? The Question answers it self: For the dissimilar Leaves, for very reason are so thin, because so very broad or long; as we see many things, how much they are extended in length or breadth, so much they lose in depth, or grow more thin; which is that which here befalls the now effoliated Lobes. For being once disimprisoned from their Coats, and the course of the Sap into them now more and more encreased, they must needs very considerably amplifie themselves; and from the manner wherein the Seminal Root is branched in them, that amplification cannot be in thickness, but in length or breadth: In both which, in some dissimilar Leaves ’tis very remarkable; especially in length, as in those of Lettice, Thorn-Apple, and others; whose Seeds, although very small, yet the Lobes of those Seeds growing up into Dissimilar Leaves, are extended an Inch, and sometimes more, in length; though he that shall attempt to get a clear sight of the Lobes of Thorn-Apple, and some others, by Dissection, will find it no easy Task; yet is that which may be obtained. From all which, and the observation of other Seeds, I at last found, that the dissimilar Leaves of a young Plant, are nothing else but the Lobes or main Body of its Seed: So that as the Lobes did at first feed and impregnate the Radicle into a perfect Root; so the Root being perfected, doth again feed, and by degrees amplifie each Lobe into a perfect Leaf.
The Original of the dissimilar Leaves thus known, we understand, why some Plants have none; because the Seed either riseth not, as Garden-Beans, Corn, &c. Or upon rising, the Lobes are little alter’d, as Lupines, Pease, &c. Why, though the proper Leaves are often indented round; the dissimilar, like the Lobes, are even-edg’d. Why, though the proper Leaves are often hairy, yet these are ever smooth. Why some have more dissimilar Leaves than two, as Cresses, which have six, as the Ingenious Mr. Sharrock also observes; the reason whereof is, because the Main Body is not divided into two, but six, distinct Lobes, as I have often counted. Why Radishes seem at first to have four, which yet after appear plainly two; because the Lobes of the Seed have both a little Indenture, and are both plaited, one over the other. To which we might add,
The use of the dissimilar Leaves is, first, for the protection of the Plume; which being but young, and so but soft and tender, is provided with these, as a double Guard, one on either side of it. For this reason it is, that the Plume in Corn is trussed up within a membranous Sheath; and that of a Bean, cooped up betwixt a pair of Surfoyls; but where the Lobes rise, there the Plume hath neither of them, being both needless.
Again, that since the Plume, being yet tender, may be injured not only by the Air, but also for want of Sap, the supplies from the Root being yet but slow and sparing; that the said Plume therefore, by the dissimilar Leaves, may have the advantage likewise of some refreshment from Dew or Rain. For these having their Basis a little beneath that of the Plume, and expanding themselves on all sides of it, they often stand after Rain, like a Vessel of Water, continually soaking and supplying it, lest its new access into the Ayr, should shrivel it.