Evening star. [volume] (Washington, D.C.) 1854-1972, 1897-10-02
AUTUMN LEAVES.
The Changes fn Color Explained
Scientifically.

Scientifically.
From tiarper's Magazine.
The casting OF the leaf is not a sudden<
ana quick response to any single change in
ehNlronmental conditions. but IS brought
ABOUT with a complex interplay OF pro-
cesses begun days or perhaps weeks before
any external changes are to be seen. The
lear Is rich i'm two classes of substances
one of which is of no further benefit 10 IL.
ana another which IT has constructed at
great expense of energy, and which is i'm
form or the highest possible usefuln, IS
TO the plant To this class belong the COM
pounds in the protoplasm the green color
bodies, and whatever surplus food may not
nave been previously conveyed away The
substances which the plant must needs dis
caro- are In the form of nearly insolube
crystals and by remaining in position i'm
the lear, drop with IL TO the ground and
pass INTO that great complex laboratory OF
the soil where by slow methods of disfu-
tesraton useful elements are set free. and
once again may be taken up by the tree AMI
uaNei .heir devious course through root
hairs along the sinuous roots and mn
through million-celled columns of the
trunk, out through the twigs to the leaves
once more.
The plastic substances within the lear
winch would be a loss to the plant IL
thrown away, undergo quite "A different
series or changes. These substances are i'm
the EXTREMIST parts OF the leaf, and TO pass
INTO the plant body must penetrate many
hundreds of membranes by diffusion INTO
the long conducting cells around the ribs or
nerves, and then down into the twigs and
STEMS The successful retreat of this great
mass of valuable matter is not a simnl.
problem. These substances contain nitro
gen as part of their compounds and as a
consequence are very readily broken down
when exposed to the sunlight In the living
normal leaf the green color forms a MOST
eHectual shield from the action of the sun
Out when the retreat is begun, one of the
frst steps results i'm the disntagration of
the chlorophyll. This would allow the
fierce rays of the September sun to strike
directly through the broad expanses of the
leaf, destroying all within were not other
means provided for protection. In the first
place, when the chlorophyn breaks down.
among the resulting substances formed rs
cyanophyll (biue), which absorbs she suns
rays in the same general manner as the
chlorophyll. In addition. the outer layers
of cells of the leaf contain other pigments
some of which have been masked 10y tie
chlorophyll, and others which are formed
as decomposition products, so that the leaf
EXHIBITS outWardly a gorgeous panopy of
colors in reds, yellows and bronzes that
make up the autumnal display. From the
wild riot of tints shown by a clump OF
trees or shrubs, the erroneous impression
might be gained that the colors are acct
dental in their occurrence. This is far from
the case, however. The keynote of color I'm
any species is constant. with minor and
local variations. The birches are a golden
yellow: oaks vary through yellow orange
to reddish brown: the red maple becomes a
dark red; the tulip tree light yellow: haw-
thorn and poison oak become violet: while
the sumacs and vines take on n flaming
scarlet. These colors EXHIBIT some varia-
ton I'm accord wiJh-t-ST character of the SCH
on which the plants stand.