The copper country evening news. [volume] (Calumet, Mich.) 18??-1907, 1897-10-01
AUTUMN LEAVES.
Their Changes In Color Explained scien-
ttdcaIly by Professor MacDougai.


The casting of the leaf is not sudden
and quick response to any single change
i'm environmental conditions, but Is
brought about with complex interplay
of processes begun days or perhaps weeks
before any external changes are TO be seen
The leaf Is rich in two classes OF SUD
stances, one of which Is OF no further Den-
eft TO it., and another which 1t has CON
structed at great expense OF energy, ana
which is i'm form of the highest possible
usefulness to the plant. To this class De-
long the compounds in the protoplasn,
the green color bodies, and whatever sur
plus food may not have been previously
conveyed away The substances which
the plant must needs discard are IN the
form of nearly insoluble crystals ana by
remaining i'm position in the leaf drop
with il TO the ground and pass into that
great complex laboratory OF the SOIL where
by slow methods of disintegration useiul
elements are set free and once again may
be taken up by the tree and travel their
devious course through root hairs along
the sinuous roots and up through million
celled columns of the trunk, out through
the twigs to the leaves once more.
The plastic substances within the leaf,
which would be a loss TO the plant IL
thrown away, undergo quite different
series of changes These substances arc
in 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 simple problem. These substances
contain nitrogen as part OF their COM
pounds, and rs a consequence are very
readily broken down when exposed to the
sunlight. In the living normal leaf the
green color forms most offectual shield
from the action of the sun, but when tho
retreat is begun one of the first steps re-
suits in the disintegration of the chloro-
phyll. This would allow the fierce rays OF
the September sun to strike directly
through the broad expanses of the leaf, de-
stroying all within, were not other means
provided for protection In the first place.
when the chlorophyll breaks down among
the resulting substances formed is cyano-
phyll (blue), which absorbs the suns rays
in the same general manner as the chloro-
phyll. In addition, the outer layers of
cells of the leaf contain other pigments,
some of which have been masked by the
chlorophyll, and others which are formed
us decomposition products, so that the leaf
exhibits outwardly a gorgeous panoply of
colors in reds, yellows and bronzes that
make up the autumnal display.
From the wild riot of tints shown by
clump of trees or shrubs the erroneous
impression might be gained that the col
ors are accidental in their occurrence.
This is far from the case, however. The
keynote of color in 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 u dark red, the
tulip tree a light yellow, hawthorn and
poison oak become violet while the
sumacs and vines take on flaming scar
let. These Colors exhibit some variation
in accord with the character Of the soil on
which the plants stand II MacDou-
gal in Harper's Magazine For October