The Barre daily times. (Barre, Vt.) 1897-1959, 1917-11-27
WHY LEAVES CHANGE COLOR.
1t Is Due to Certain Chemical Processes
Taking Place.

II requires no vivid imagination ia
picture Mother Nature going about these
days with liberal supply of paint with
which she colors the leaves of the trees
and other plants and thereby produces
the vivid tints which characterize the
foliage of this season. In reality the
change in coloring is the result of certain
chemical processes which take place in
the leaves.
The change is not as many people sup
pose, due to the action of frost but Is
a preparation for winter All during the
spring and summer the leaves have
served as factories, where the foods neces-
sary for the trees growth have been
manufactured. This food making takes
place in numberless tiny cells of the leaf
and is carried on by small green bodies
which give the leaf its color. These
chlorophyll bodies, as they are known,
make the food Of the tree by combining
carbon taken from the carbonc acid gas
of the air with hydrogen, oxygen, and
various minerals supplied by the water
which the roots gather. In the fall when
the cool weather causes a slowing down
of the vital processes, the work OF the
leaves comes to an end. The machin'
cry of the leaf factory is dismantled, so
to speak, the chlorophyll is broken up
into the various substances OF which 1t
is composed. and whatever food there is
on hand is sent to the body of the tree
to be stored up for use in the spring.
All that remains in the cell cavities of
the leaf is watery substance in which
few oil globules and crystals, and a
small number of yellow, strongly refrac-
tive bodies can be seen. These give the
leaves the yellow coloring so familiar in
autumn foliage.
1t often happens, however, that there
is more sugar in the leaf than can be
readily transferred back to the tree
When this is the case the chemical COM
with the other substances pro
duces many -colored tints varying from
the brilliant red of the dogwood to the
more austere red-browns of the oak in
coniferous trees, which do not lose their
foliage in the fall, the green cooring
matter takes on slightly brownish
tinge, which, however, gives way to the
lighter color in the spring.
While the color of the leaf is changing, |
other preparations are being made. At
the point where the stem of the leaf as
to the tree, special layer OF
cells develops which gradually sever the
tissues which support the leaf. At tie
same time nature heals the cut, so that
when the leaf is finally blown off by
The wind or falls from its own weight,
The place where it grew on the twig is
marked by scar.
Although the food which has been pre-
pared in the cell cavities is. sent back to
he tree, the mineral substance with
which the walls of the cells have become
during the summer months
ire retained. Accordingly, when the
caves fall they contain relatively large
amounts of valuable elements, such as
nitrogen and phosphorus which were orig
nally part of the soil. The decom
position OF the leaves results in enrich
ng the top layers of the soil returning
hese elements and by the accumulation
Il humus. That is why the mellow black
arth from the forest floor is so fertile.
3ut if fires are allowed to run through
he forest and the leaves are burned, the
most valuable of the fertilizing elements
re changed by the heat into gases and
scape into the air. As a result, forests
yhich are burned over regularly soon
,se their soil fertility even if no APP
aren't damage is done to the standing {
imber. 4