South Bend news-times. (South Bend, Ind.) 1913-1938, 1917-11-03
STOCK-RALSLNG
WHY THE LEAVES
CHANGE COLOR

IL requires no vivid Imagination
TO picture Mother Nature going
about these days with liberal sup
ply 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 colorings IS the re-
suit OF certain chemical processes
which take place in the leaves
The change is not, as many peo-
I pie suppose. due 10 the action of
frost out is 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
3 carbon taken from the CarhOnic
acid gas of the air with hydrogen,
: oxygen. and various minerals sup
/ piled by the water which the roots
gather. In the fall when the cool
weather causes slowing down OF
/ the vital processes. the work Of
/ the leaves comes TO an end. The
machinery of the leaf factory is
: disnantled. so 10 speaN. the chloro-
7 phyll is broken mp into the various
substances of which it is composed,
/ and whatever food there il on hand
/ is sent 10 the body of the tree 10
, be stored up for use in the spring.
/ All that remains I'm the cell cavi-
ties of the leaf is watery sub
stance in which a few oil Slobules
and crystals. and small number
Of yellowish. strongly retroactive
bodies can he seen. These give the
leaves the yellow coloring SO IA
miliar i'm autumnal foliage.
IL often happens, however. that
there is more sugar i'm the leaf
than can be readily transferred
! back to the tree. When this Is tlH
case the chemical com bination with
the other substances produces many
colored tints varying from the bril-
liant red Of the doewoOd TO the
more austere red-brOwns OF the
oak. In coniferOus trees. which do
10 not lose their foliage in the fall,
the green colOring matter takes on
a slightly brownish tinge. which,
however. gives way TO the lighter
color in the spring.
&c
changing, other preparations are
being made At the point where
the stem of the leaf is attached TO
the. tree. a special layer of cells
develops which gradually sever the
tissues which support the leaf At
the same time nature heals the
cut. 50 that when the leaf is finally
blown off by the wind or falls from
its own weight, the place where il
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 mineraI sub
stances with which the walls Of the
cells have been impregnated during
the summer months are retained.
Accordingly. when the leaves fall
thew contain relatively large
amounts of valuable elements such
as nitrogen and PHOSPHORUS which
were originally a part of the soil.
The decomposition of the leaves re-
suits I'm enrichins the top LAYERS of
the soil by returning these elements
and by accumulation Of humus.
That is why the mellow black earth
| from the forest floor is so fertile.
But If fires are allowed TO run
/ through the forest and the leaves
are burned, the most valuable Of
the fertilizing elements are changed
! 10y the heat into gases and escape
into the air. A. a result. forests
which are burned over regularly
soon lose their soil fertility even if
no apparent damage Is done TO the
standing timber