The Hartford republican. (Hartford, Ky.) 18??-1926, 1917-11-02
WHY TBE LEAVES
GHANGE THEIR COLOR

Washington, October st re-
auires no vivid imagination to pic
ture Mother Nature going about
those days with liberal supply of
paint with which she eolors 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 col
oring is the result of certain chemi-
cal processes which take place in
/ the leaves.
The change is not, as many people
suppose, 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 necessary for the trees
growth have been manufactured.
This food making takes place in num-
berless tiny cells of the leaf and is
carried on by small green bodies
which give the leaf its color. These
chorophyll bodies, as they are
known, make the food of the tree by
/ combining carbon taken from the
carbonic acid gas of the air with
hydrogen, oxygen, and various miner
ais supplied by the water which the
roots gather. In the fall when the
cool weather causes a slowing down
Z OF the vital processes, the work OF the
leaves comes to an end. This ma?
chinery of the leaf factory is dis
mantled, so to speak. the chlorophyil
is broken up into the various sub
stances of which it 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 a watery substance in
which a few oil globules and crys-
tails, and a small number of yellow,
strongly retroactive bodies can be
seen. These give the leaves the yell
low coloring so familiar in autumnal
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 combination with the other
substances many-colored tints vary
ing from the brilliant red of the dog
wood to the more austere Ted-browns
of the oak. In coniferous trees,
which do not lose their foliage in
the fail, the green coloring matter
takes on a slightly brownish tige,
which, however, gives way to the
lighter color in the spring.
While the color of the leaf is
changing, other preparations are be-
ing made. At the point the stem of
the leaf is attached to the tree.
special layer of cells develops which
gradually sever the tissues which
support the leaf. At the same time
/ Nature heals the cut, so that when
the leaf is finally blown off by the
wind or falls from it's own weight,
the place where it grew on the twig
is marked by a scar.
Although the food which has been
prepared in the cell cavities is sent
back to the tree, the mineral sub
stance with which the walls of the
cells have become impregnated dur
ing the summer months are retain
ed. Accordingly, when the leaves
/ fall they contain relatively large
| amounts of valuable elements, such
as nitrogen and phosphorus which
were originally a part Of the soil.
I The decomposition OF the leaves re-
suits in enriching the top layers of
the soil by returning these elements
/ and by the accumulation of humus.
| That is why the mellow black earth
/ from the forest floor is SO fertile.
but il fires are allowed to run
/ through the forest and the leaves are
/ burned, the most valuable of the fer
tlzing elements are changed by the
/ heat into gases and escape into the
air. AS a result, forests which are
burned over regularly soon loose
their soil fertility even il no APP
parent damage is done TO the stand
ing timber.