But although the openness of the Ayr permitting be alwayes alike; yet the Energy of the _Sap_ effecting; being different; as therefore that doth, the dilatation of the _Trunk_ will also vary. If that be less, so is this; as in the _Trunks_ of most Trees: If that be greater, so is this; as in Plants is common; the _Lignous Body_ being usually so far dilated, that the _utmost shootings_ thereof may easily be seen to jut out, and adjoyn to the Skin. And if the _Sap_ be still of greater energy, it so far dilates the _Lignous Body_, as not only to amplifie the _Pith_ and all its Pores; but also so far to stretch them out, as to make them tear. Whereupon either running again into the _Cortical Body_, or shrinking up towards it, the _Trunk_ thus sometimes becomes an _hollow Stalk_, the _Pith_ being wholly, or in part voyded. But generally it keeps entire; and where it doth, the same proportion and respect to the _Lignous_ and _Cortical Bodies_, as is said. The Consequences of all which will be, the strength of the _Trunk_, the security and plenty of the _Sap_, its Fermentation will be quicker, its Distribution more effectual, and its Advancement more sufficient. First, the erect growth and strength of the _Trunk_; this being by the position of its several parts effected: For besides the slendering of the _Trunk_ still towards the top, the Circumferential position of the _Lignous Body_ likewise is, and that eminently hereunto subservient: So that as the _Lignous Body_ in the smaller part of the _Root_ standing Central, we may thence conceive and see their pliableness to any oblique motion; so here, on the contrary, the _Lignous Body_ standing wide, it thus becomes the strength of the _Trunk_, and most advantageous to its perpendicular growth. We see the same Design in _Bones_ and _Feathers_: The strongest _Bones_, as those in the Legs, are hollow. Now should we suppose the same _Bone_ to be contracted into a Solid Body, although now it would be no heavier, and in that respect, as apt for motion; yet would it have far less strength, than as it is dilated to a Circumferential posture. And so for _Quills_, which, for the same Reasons, in subserviency to flight, we see how exceeding light they are, and yet, in comparison with the thinness of their Body, how very strong: We see it not only in Nature, but Art. For hence it is that _Joyners_ and _Carpenters_ unite and set together their Timber-pieces and several Works oftentimes with double Joynts; which, although they are no thicker than a single one might be made, yet standing at a distance, have a greater strength than that could have. And the same Architecture will have the same use in the _Trunks_ of Plants, in most whereof ’tis very apparent; as for instance, in Corn: For Nature designing its _Sap_ a great Ascent for its higher maturity, hath given it a tall _Trunk_; but to prevent its ravenous despoiling either of the Ear or Soyl; although it