Martinsburg gazette. [volume] (Martinsburg, Va. [W. Va.]) 1833-1855, 1854-02-15
5ficnfe ano Art.
POPULAR ERORS ABOUT the RISE AND
FALL OF sSAP.n


nv Psor. LISDLaY, UNIVERSITY OF losDox.
What curious hallucination is that which
supposes the sap of trees to fall or settle in
the winter into the roots One might have
thought that the notorious difficulty of cram
ming quart of water into pint measure,
might have suggested the improbability of
such phenomenon. For it certainly does
require large amount of credulity to believe
that the fluids of the trunk and head of
tree can, by any natural force of compression,
be compelled to enter SO narrow lodging as
| the root.
The idea, however, has established itself
in some persons minds, and we presume, in
connection with that other old vulgar error,
that the sap is in rapid motion in the spring
time, in the roots Of tree before it begins to
flow in the branches. These WITNESSES took
their origin in the days when the world was
content 10 except assertions upon trust, and
when hypothesis and vain imaginings formed
the debased paper currency of science. But
now men have found out the value Of a golden
standard, both for money and for knowledge
| they call for facts before theories, and the
result is wonderful disturbance in the
| crowded ranks Of scientific as well as histor-
ical legends.
We shall assume the word sap to signify
| tt,aa a. 1fx hat -
tanned in the interior of a tree. In the spring
thesap runs out Of the trunk when it is wound
ed in the summer, autumn and winter it
does not, unless exceptionally, make its APP
pearance. But, in truth, the sap is always
in motion, in all seasons and under oil
circumstan ces, except in the presence of in
tense cold. The difference is, that there is
a great deal of it in the spring, and much less
at other seasons.
When tree falls to rest at the approach
Of winter, its leaves have carried off so much
more fluid than the roots have been able to
supply, that the whole of the interior is in a
state of comparative dryness, and large por-
ton of that sap which was once fluid has be-
come solid in consequence of the various
chemical changes it has undergone. Be-
tween simple evaporation on the one hand,
and chemical solidifcation on the other, the
sap is, in the autumn, so much diminished in
quantity as to be no longer discoverable by
mere missions. The power that a plant may
posses of resisting cold is in proportion to the
completeness of this drying process.
When the leaves have fallen off, the tree
is no longer subject to much loss eff fluid by
Precipitation and assimilation. But the abb
sorbing power of the roots is not arrested
they, on the contrary, 60 on sucking fluid
from the soil, and driving itupwad Is into the
system. The effect of this is, that after some
months of such an action, the loss of fluid that
the tree had sustained in autumn by its leaves
is made good, and the whole plant is distend-
ed with watery particles. This is most
wise provision in order to insure abundant
food to the new born leaves and branches
when warmth and light stimulate them into
growth.
During all the winter period the sap APP
pears to be at rest, for theire-6lling process
is very gradual one. But Nlr. Blot, many
years ago, proved, by an ingenious apparat-
us, that the rate of motion of the sap may be
measured at all seasons, and he ascertained
it to be in state of considerable activity in
mid-winter.
Among other things he found that the frost
had considerable influence upon the direction
in which the sap moves. In mild weather.
the sap was constantly rising, but when frost
was experienced the sap flowed back again
a phenomena which he referred to the con-
tracing power of cold on the vessels of the
trunk and branches, the effect Of which was