VEGETABLE STRUCTURE. 
75 
as It were, at fmall dlflances, with a kind of oval Glands, 45, b. In thefe 
there is no fimple aperture, as there is in the fwellings of the VeiTels of the 
outer Bark ; but they feemed pierced all over with very minute holes, from 
which there iffues a whitidi fluid, thicker than the Juice of the outer 
Bark. 
Beside thefe prominent parts, whofe purpofe plainly is to difcharge an 
abundant mcifture, there are others of the fame form, and equally nu- 
merous, which are of a duficier colour, and are a little hollowed inward. 
The office of thefe feems to be to receive. 
There are diftindlly (hewn in the large Veffels, at the Figures 48 and 
/jp; the firft of which reprefents a piece of a fingle couch of this Rind, 
with its two Membranes fcparated, as it appears before a very great power 
to the Double Microfcope ; and the latter, the Veflcls of the fame part 
taken out from between thofe Membranes. 
After this examination of a fingle Couch of the inner Rind, it will 
be proper to examine the feveral together which make up its whole thick- 
nefs. We find by this view, that the Veffels in all thefe Couches are 
united to one another, by thofe fhort obliquely difpofed Veffels, which we 
call the Bars of Union ; but that there are none fuch between the Veffels 
of this Rind and of the two diftindt fubfiances placed next to it. 1 he 
communication between the outer Rind and this, is only by the mouths of 
the Veffels of the outer Bark, which open into the interflice between the 
two, and thofe of the inner Rind, juft deferibed as depreffed, not rifing 
above the furface. This is the more certain, becaufe there are only the 
deprefl'ed mouths on the outfide of thofe Veffels of the inner Rind, which 
form the outer Couch, and come next to the outer Bark. This is expref- 
fed in the Figure 48, which is the outer furface of a piece of the outer- 
moft Couch of this inner Rind j and in 49, which exhibits the fame fur- 
face of two of the Veffels taken from between thofe Membranes. It ap- 
pears by thefe examinations, that the crofs-bars which join the afeending 
Veffels one to another, are alfo tubular, for they have the fame mouths 
upon them. 
By thefe gradual advances w'e make fome progrefs toward a knowledge 
of the Vegetable Strudlure : we fee the communication between the feveral 
Couches, which together compofe one fubftance, is of one kind, and that 
between one fubftance of the Plant and another, is of a diftindl fort. Thus 
the Veffels of the feveral Couches which form the inner Rind, are united 
fimply by tubular bars, in the fame manner with the feparate \'effels of 
the fame Couch 3 the original Juice received into the part paffing with 
L 2 equal 
