The Vermont watchman. [volume] (Montpelier, Vt.) 1883-1911, 1885-06-03

water sap go up the tree from the roots?
This is discussed at length by Clark,
and the theories of many writers are
reviewed and their inconsistencie noted.
1t has been proved that water will be
absorbed by either end of living shoot,
and flow to all parts of it. Though a
plant naturally gets its soil water
through its roots, experiments have
shown that if a sucker springing from
a root at some distance from the parent
tree is cut free from the roots beyond,
and raised out of the ground, it will
still grow and flourish from root sap
drawn up by the roots of the tree, and
transmitted to it through the connect
ing roots-that is, the sucker becomes
branch. If we place the cut end of
growing branch in water, that branch
has power to draw up enough of that
water to keep itself fresh, and its leaves
from whitening for some time. Be-
sides this, in many cases it will throw
out roots from the cut end, and become
an Independent tree or shrub There
is evidently a strong upward drawing
power for fluids possessed by every
growing plant, and this power, though
naturally strongest in the roots, is pos
sessed by every fragment of the living
vegetation, even to the single leaf.
The great majority of trees and
shrubs do not bleed-that is, the sap
will not flow out from wounds at any
season of the year. Though the willow
grows in water it will not bleed at any
time, while the birch or the maple,
growing on the dry hilltop will shed its
sap from wound profusely at certain
seasons, and of these each has its own
season. Professor Clark found that
the sugar maple Gin Massachusetts, be-
gins to flow in October, reaches its
greatest flow about the first of April,
and ceases about the first of May. The
black birch begins the last of March,
has its greatest flow the last of April,
and stops about the middle of May.
The wild grapevine begins about the
middle of May, reaches its height about
May 20 and ceases early in June. The
maple sap contains mostly cane sugar,
the birch sap grape sugar, and the grape
vine sap gum. But it should be noted
that these are different forms of the
same thing, their chemical composition
being identical, except in their proper
tons of water, and all have the like
identity with starch and with woody
fibre. They are all probably formed
from the starch stored up in the pre-
vious years growth. Professor Clark
thinks that to produce the higher form,
cane sugar, requires more time than to
form grape sugar, or gum, which are
lower (more watery) compounds. The
maple has more enduring absorptive
power, and keeps full of root-water all
winter, while the birch is less active,
and the grape becomes active only as
spring advances.
The daily and hourly flow of maple
sap varies with the weather. The most
unfavorable weather is that which is
steadily and severely cold, or uniformly
warm and foggy, while the best sap
days are such as are warm and sunny,
after freezing nights. Professor Clark
gives as the best explanation of this
that the outer tissues of the tree are
partially emptied of their contents by
the contracting influence of cold, the
sap being driven into the heart-wood
and large roots. We do not regard this
as satisfactory explanation.
Professor Clark made many expert
ments as to the quantity of sap to be OBJ
tanned from holes of different depths,
and on different sides of the tree. He got
agood but not large flow from a hole six
inches deep, tubed with gas piping, and
found freer and longer flow from the
north than from the south side of the
same tree. These experiments need re-
peating. He also found that the higher
he tapped the less sap he got. This is
the general experience, and it is natural
to suppose that the nearer to the water
supply-the ground-the more water
would flow. But this does not prove
that there is more sugar there. II
may show the absence of sufficient
water above to dissolve it and carry il
out of the wound. Experiments upon
the roots of naples showed that saI
would flow from both ends of cut root
and that it all contained sugar.
A mercurial gauge, an instrument
carefully made to test pressure, like
those upon steam boilers, was attached
to maple tree, and showed great vari
atoms. In the morning the gauge
usually stood below zero-that is, there
: was not only no outward pressure, bu
there was an inward draught, I" indi
J eating powerful suction into the tree
But it should be remembered that this
| " suction into the tree" was only posi-
BILE on account Of the hole made in it
} What was really indicated was that thu
| sap hung inactive in its channels, like