22 EX P L A I N E D BY THE MICROSCOPE.
P L A T E differentdiftinces are difpoied among it oblong.clufters of different veiTcIs. TJiefe
clufters are ufually eight or ten in number; and give origin to the angles of the Corona.
They are not uniform or of one kind of veffels, as in thofe in the Bark, but •
each has two diftinft forts; the extcHor ones anfwering to the Blea, and the interior
to the Wood of Trees: and within each of thefe are alfo difpofed veffels not unlike
thofe in the Blea and Wood, and often even larger than they are found in thofe parts
in the Shoot.
Thus we fee that each clufter of the Corona is compofed of all the effential parts
of the fucceeding Branch, and thit the inteimediate parts of the circle are abfoiute
Bark and Rind, ready to follow and cloath the clufter when it goes off in the form
o f a Shoot; becaufe it will then need their covering and defence, tho' in its prefent
inclofed ftate it does not.
I t is frotn this conftruGion that a T ree is at all times, and in all parts, ready to ihoot
out Branches j and every Branch in the fame mannfer to fend out others: for the
whole Trunk, and the Branch in all its length, have this courfe of eight or ten clufters
of effential veffels ready to be protruded out, and the proper and natural integuments
as ready to cover them.
I n fome trees thefe parts are more evident, in others more obfcurely arranged j but
when their nature is known, theje is none in which they may not be found.
T h e Oak is not one of thofe trees in which they are moft confpicuous and diftindt:
yet wi l l the moft curfory obferver perceive, in a tranfverfe feaion of a Shoot of that tree,
that the circle immediately furrounding the Pith is perfeftly diftind, both from the
P i t h which it enclofes, and from the Wo o d which furrounds it. A feftion o f the Oak
Eig- I • is given for this purpofe at Plate IX. Fig. i. and near it, at Fig. 2. is placed a fedion
F i g . 2. of that tree, in which, of all that I have had the opportunity of examining, this circle
is the moft diftindt. This is the Parrot Wo o d of the Wef t Indies, the Bocconia of
Botanical writers : it feems formed to lay open this great myftery of Nature j for nothing
can be fo palpable as the conftrudtion : 'twere well if this fpecies were at hand
in Europe ; probably it will be foon : in the mean time, the only Vegetable wherein
the parts can be fcen in a manner any thing refembling this, is an herbaceous Plant,
the greater Celandine; to which indeed this Bocconia is in its Botanical charaSers, as
well as in its inner ftrufture, very nearly allied.
T h i s tranfverfe fcdlion of a Shoot of the Bocconia is given at Plate IX. Fig. 2. With
what fuperior beauty muf t it appear from a frefti Branch f for this was from one brought
f r om Jamaica, and rendered manageable to the knife by a long infufion in water. We
fee here tlie Rind a, with its Bark underneath, ¿ j and the Vafa exteriora and interiora
evidently mark'd in them. Beneath thefe, at e, lies the Blea, perfeitly diftinguiihable
f r om them, but fcarce at all from the Wood,_/i the Branch being very young and tender.
But even in this ftate the part immediately within the Wood is moft palpably diftinft :
its fubftance, ftrufture, colour, every thing, ihew that it is neither of the nature o f the
Wood, nor of the Pith, equally unlike both : and within this, but extending each way
beyond it, are thofe clufters of veffels which we find in all Coron», tho' lefs di f t inf t :
thefe intrench upon the Pith one way, and upon the W o o d itfelf another; being in their
P'S