The wood, or ligneous part, is not essential, many 
d 
plants being without it; = 
plants that are hollow wi 
$ grasses, reeds, and all 
The hollow Oak-trees and Willows, are often seen 
with the whole wood decayed aa __ and yet the 
few remaining branches flourish with vigor. 
Grasses, properly speaking, have only the cortical 
The thin or cover of the bark is of great 
t is of great strength, and ap- 
pears 
which is ro. re earth, as 
he Stalks are othond parts which branch out from the 
<. and support the leaves, flowers, or fruits; as the 
straw in grasses; the flower stalks, leaf s i as. 
The Pith is a tolerably firm juicy substance, which 
is diffused through the inner part of the stalk, to give 
energy and vigor to the whole; it is abundant in young 
plants, diminishes as they grow up, and at length to- 
disappears. - 
The Sap is the fluid which budtaties the plant. The 
warmth of the spring dilates the vessels of plants, pro- 
m the soil, and if the plant be annual, its 
life then terminates; if not, it remains in a state o 
torpor during the winter. The basis of this juice, which 
the roots suck up from the soil, is water 
eat promotes Ses it ie: 5 Se cee of 
plants; it increases siti eir con- 
stituent parts for new attraction and combination, to 
too great, or continued for too long a time, as it oc- 
casions a too rapid digestion and perniiradicn » their 
nourishment, and consequently an ustion. 
= have an pe, heat of their own. But, 
if it r the spontaneous produc- 
> mu much more so to account for the = 
eration of vegetable heat. Light and atmospheric air, 
at least, are known to be essential to the vital Fie ns 
both. 
In all decomposition, caloric, or heat, is disengaged, 
be several degrees 
phere, when it was below the fifty-sixth division of 
Fabra whereas, the vegetable heat in hotter wea- 
that the sap which, owt of the tree 
did not freeze in the a8 unless the cold were augment- 
ed 15° more, 
But the most remarkable instance of heat in plants 
upon record, is what is related of the Arum maculatum. 
Lamarck says, in his Flore Francaise, ‘‘that when the 
—s are in a certain state of perfection, the spadix 
so hot as to seem burning, and not at all of the same 
pS as the surrounding bodies.’’ 
r. Senebier noticed that this eal began when the 
shaath® was about to open, and the a just peeping 
forth, and that it was perceptible from t 
o’ clock in the afternoon til] midni 
The Leaves consist of an immense number of fibres 
or nerves, divided into two sets, one belonging to each 
surface. The surface of the leaf is full of minute pores, 
through which it imbibes the dew, air, &c., necessa 
to the growth of the plant, so as to enable it, in some 
degree, to dispense with supplies from the root; as we 
ts wh 
action of Se causes its disengagement.—_{ See Note or 
upon 
Air is ess necessary to the growth of a plant. But 
the air which it requires is not the same appropriated 
to the use of man. 
aera irl, cate kind of calya that opens lengthwise, 
Pp , as in the palm, arum, 
is also applied to the calyx of some flowers gcson have 
no ae as of the it Sy eae iris, &. A membrane 
estin, 
in grasses. 
le proceeding from a spathe, as in the 
m, and some other plants, so called from being produced 
iene a spathe or sheath. 
Os ‘ 
