VEGETABLE STRUCTURE. 
19 
we call the upper and under Membranes of the Leaf: thefe are really one 
The Leaf is a fpungy body, covered by the extended and dilated Mem- 
brane of the Footdalk; which does not feparate at the extremity, but, on 
the contrary, is more firm and compact there tiian elfewhere, from the 
innumerable inofculations of its Vefi'els : it forms in that part a khad of 
flat cord furrounding the Leaf. 
If we take off this Membrane, which m y be done by due maceration, 
vve find the Veffels difpofed in the ufual way, in that part of it w’hich 
covered the Footftalk, and the Membrane entire and unperforated between 
them : but in that part which covers (he body of the Leaf, thefe Vcficis 
are feparated to a greater diflance; and in the plain Membrane between 
them, there are innumerable oval apertures. This is flaewn in Fig. 53, 
which reprefents the outer Baik of the Footflalk and Seed-Leaf entire : 
^ flaews the courfc of the Veffels in tlae Footflalk, with the Membrane 
entire between them ; and the fame Veffels in the coat of the body 
of the Leaf, where they are more feparate, and have thofe oval apertures 
between them. We therefore fee, that whatfoever is the office of the Leaf, 
the Footflalk does not perform any pirt of it in common, but ferves 
only to raife the effective part of the body of the Leaf to a proper height 
in the free air. 
Under this outer Bark is fpread the inner Rind. They are diflinguiflied 
by their colour and confiflence : the outer Rind being very thin, and per- 
fedly pellucid ; the inner Rind fomewhat thicker, a little cloudy, and 
green. This is, in the fime manner as the other, continued from the Root 
thro’ the Stalk to the Leaf, where it expands, and confequently the Vef- 
fels become more feparated: the Membrane between thefe Veffels is entire 
on the Footflalk, as the other j but in that part which covers the body 
of the Leaf, it is pierced with innumerable holes : thefe are much fmaller 
than the mouths of the outer Bark, but they many times exceed them in 
number; and they are not oval, as thofe, but round. This fecond Rind 
of the Leaf is reprefented at Fig. 54. 
These make the coverings of the Leaf; but its thick fubflance is form’d 
by the Blea : this runs between thefe double coats, and is a mafs of 
fpunge. 
We know the flrudure of the Blea ; and in the Leaf this is the fame 
as in the Stalk, only for the different difpofition. The Blea of all Plants 
is a mafs of cells, formed of Membranes, and fupported and feparated by 
Veffels. In the common courfe of the Blea in the Stalks, and other parts 
of the Plant, the cells of it run flrait between the coats ; but in the body 
of 
