of a considerable part of its moisture, contains
a much greater proportion of solid matter, which retards its motion. It
does not appear that there is any excess of descending sap, as none ever
exudes from the roots of plants; this process, therefore, seems to be
carried on only in proportion to the wants of the plant, and the sap
descends no further, and in no greater quantity, than is required to
nourish the several organs. Therefore, though the sap rises and descends
in the plant, it does not appear to undergo a real circulation.

The last of the organs of plants is the _flower_, or _blossom_, which
produces the _fruits_ and _seed_. These may be considered as the
ultimate purpose of nature in the vegetable creation. From fruits and
seeds animals derive both a plentiful source of immediate nourishment,
and an ample provision for the reproduction of the same means of
subsistence.

The seed which forms the final product of mature plants, we have already
examined as constituting the first rudiments of future vegetation.

These are the principal organs of vegetation, by means of which the
several chemical processes which are carried on during the life of the
plant are performed.

EMILY.

But how are the several principles which enter into the composition of
vegetables so combined by the organs of the plant as to be converted
into vegetable matter?

MRS. B.

By chemical processes, no doubt; but the apparatus in which they are
performed is so extremely minute as completely to elude our examination.
We can form an opinion, therefore, only by the result of these
operations. The sap is evidently composed of water, absorbed by the
roots, and holding in solution the various principles which it derives
from the soil. From the roots the sap ascends through the tubes of the
alburnum into the stem, and thence branches out to every extremity of
the plant. Together with the sap circulates a certain quantity of
carbonic acid, which is gradually disengaged from the former by the
internal heat of the plant.

CAROLINE.

What! have vegetables a peculiar heat, analogous to animal heat?

MRS. B.

It is a circumstance that has long been suspected; but late experiments
have decided beyond a doubt that vegetable heat is considerably above
that of unorganised matter in winter, and below it in summer. The wood
of a tree is about sixty degrees, when the thermometer is seventy or
eighty degrees. And the bark, though so much exposed,