These Insertions, although as is said, of a quite distinct substance from the _Lignous Body_, and so no where truly incorporated with it, yet being they are in all parts, the one as the Warp, the other as the Woof, mutually braced and inter-woven together, they thus constitute one strong and firmly coherent Body. As the Pores are greater or less, so are the Insertions also: To the bare eye usually the greater only are discernable: But through an indifferent _Microscope_ there are others also, much more both numerous and small, distinctly apparent. So that, I think, we may observe, that as the grand _Pith_ of the _Trunk_ communicates with, and is augmented by the greater Insertions; so is the _Pith_ of each greater Pore originated from the less; and those (at least) pithy parts in the Midling Pores, from others still less; and suppose, that the least of all are so far intruded into the smallest Pores, as only just to cause a kind of roughness on their concave sides, and no more; to what end shall be said. See _Fig. 17_. In none of all these Pores can we observe any thing which may have the true nature and use of Valves, which is easily to admit that, to which they will by no means allow a regress. And their non-existence is enough evident, from what in the first Chapter we have said of the _Lobes_ of the _Seed_: in whose _Seminal Root_, were there any _Valves_, it could not be, that by a contrary course of the _Sap_, they should ever grow; which yet, where-ever they turn into Dissimilar Leaves, they do. Or if we consider the growth of the _Root_, which oftentimes is upward and downward both at once. The Insertions here in the _Trunk_ give us likewise a sight of the position of their Pores. For in a plained piece of Oak, as in Wainscot, Tables, _&c._ besides the larger Pores of the _Lignous Body_, which run by the length of the _Trunk_; the Tract likewise of those of the Insertions may be observed to be made by the breadth, and so directly cross. Nor are they continuous as those of the _Lignous Body_, but very short, as those both of the _Cortical Body_ and _Pith_, with which the Insertions, as to their substance are congenerous. Yet they all stand so together, as to be plainly ranked in even Lines or Rows throughout the breadth of the _Trunk_: As the Tract of these Pores appear to the naked Eye, see in _Fig. 18_. By the best Microscope I have at hand, I can only observe the Ranks of the Pores; not the Pores themselves, saving here and there one; wherefore I have not describ’d them.