VEGETABLE STRUCTURE. 
95 
It is plainly formed by juices thrown out from the inner furface of 
the Flelhy Subftance of the Plant, and from the furfaces of the feve- 
ral Conic Cluflers of Veflels. Thefe Juices hardening on thofe furfaces 
form Velfels. Thus the Pith becomes Vafcular: and as only the furfaces 
of thefe vafcular Cones, and the intermediate inner furface of the Fkfliy 
Subftance give it origin, it muft of neceflity be circumfcribed within the 
bounds of the hollow which they form. Thus it is utterly impoffible 
the Pith of one part fhould run into the Pith of another ; and what at 
hrft appeared fo ftrange in its courfe, is the necelfary refult of its conftruc- 
tion. A tranverfe fedtion of the Pith of a Fibre of the Root, cleared from 
all the other fubftances, is reprefented at Fig. 99 ; and a like fediion of 
the Pith of the Flower Stalk, at ico. The mouths of the cells are empty 
or full of Juice as the knife has chanced to pafs thro’ an empty or a full 
part. 
The Velfels of the Pith being covered the moft of any in the Plant, 
from the air, become thence the whiteft and moft tender. They are very 
numerous, and are jointed in a manner at once fingular and highly elegant. 
Fig. 101. The Cells are of nearly an equal length and thicknefs ; fo that 
the joints are ftiorter than in the Blea, vvhofe Cells they otherwife, in fome 
degree, refemble: but there are no Veffels upon them. The Blea con- 
fifts of Cells and Veftels ; this part of Cells alone. The divifion between 
Cell and Cell are of a fpungy Membrane, full of fmall holes, which are 
fhewn at Fig. 102, a little more magnified. Through thefe the liquor 
forces itfelf in little drops, fo that the whole Veffels often appear full as It 
were of firings of minute beads. 
These Veffels arife principally from the part of the furface of Fleflay 
Subftance which makes the arch at the bafe of that portion of the Plant 
wherein they are formed. See Fig. 103, a b and from the arches of the 
conic Veffels there. P'rom this part they run to the arch at the top in a to- 
lerably ftrait courfe ; and there are again inferred in the arches of the fame 
parts. Some Veflels of a like kind and form, and which make a part of 
the fame fubftance of the Pith, are alfo fent off from the fides of the hol- 
low Cone formed by the inner furfirce of the Flefli, and Conic Cluf- 
ters ; and thefe in the fame manner run ftrait upwards, and terminate 
in the arch at the top. Fig. 104 rcprefents a fmall piece of the Pith, 
with the Veffels greatly magnified, to flaew the courfe of the chained 
globules of Juice: at J05 is a piece of the fingle Veffel viewed with the 
greateft magnifiers, with the Membrane feparating it into Cells : and this 
Membrane, with its irregular apertures, at 106. 
The 
