Having thus seen the solitary uses of the Several Parts of the _Root_, we shall lastly propound our Conjectures of that Design whereto they are all together concurrent, and that is the Circulation of the _Sap_: For the _Sap_ moving through the _cortical Body_, towards the _Pith_, through the Insertions thereinto, obtains a pass: Which passage, the superiour Insertions will not favour; because the _Pith_ standing in the same height with them, is there large, the fermenting and course of the _Sap_ quick, and so its opposition strong. But through the inferiour it will much more easily enter; because there, through the smalness of the _Pith_, the opposition is little, and through the shortness of the Insertions, the way more open. So that though the _Sap_ may meet with some opposition even here, yet here meeting with the least, here it will bestow it self (feeding the _Lignous Body_ in its passage) into the _Pith_. Into which fresh _Sap_ still entring, this, yet but crude, will subside: that first received and so become a Liquor higher wrought, will more easily mount upwards; and moving in the _Pith_, as in the _Arteria magna_, in equal altitude with the more superiour Insertions; the most volatile parts of all will still continue their direct ascent towards the _Trunk_. But those of a middle nature, and, as not apt to ascend, so being lighter than those beneath them, not to descend neither; they will tend from the _Pith_ towards the Insertions in a motion betwixt both; through which Insertions (feeding the _Lignous Body_ in its passage) it is, by the next subsequent _Sap_, discharged off into the _cortical Body_, as into the _Vena cava_, back again. Wherein, being still pursu’d by fresh _Sap_ from the Center, and more occurring from the Circumference, towards the inferiour Insertions it thus descends; through which, together with part of the _Sap_ afresh imbib’d from the Mould, it re-enters the _Pith_. From whence, into the _Cortical Body_, and from thence into the _Pith_, the cruder part thereof reciprocally is disburs’d; while the most Volatile, not needing the help of a Circulation, more directly ascendeth towards the _Trunk_. CHAP. III. _Of the Trunk._ Having thus declar’d the degrees of _Vegetation_ in the _Root_; the continuance hereof in the _Trunk_ shall next be shew’d: in order to which, the Parts whereof this likewise is compounded, we shall first observe. That which without dissection shews it self, is the _Coarcture_: I cannot say of the _Root_, nor of the _Trunk_; but what I chuse here to mention, as standing betwixt them, and so being common to them both; all their Parts being here bound in closer together, as in the tops of the grown Roots of very many Plants, is apparent. Of the Parts of the _Trunk_, the first occurring is its _Skin_: The Formation whereof, is not from the Air, but in the _Seed_, from whence it is originated; being the production of the Cuticle, there investing the two _Lobes_ and _Plume_.