Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1897-11-18
AUTUMN LEATEs.


Their Chnngss in Color Explained scien-
iihcnlly by rrof. MHcDbugHt
Tho casting Of the leaf ia not sud-
lien and quick response IL any single
change 10 environmental conditions,
ut is brought about with a complex
interplay OF processes begun dhyH or
perhaps weeks before my external
changes arc to he soen, says Prof. Mac
Dnugal in Harper's. The leaf ia rich
in two GlhsseH Of substances, nue OF
which is of no further benefit to ii.
and another which il has constructed
at great expense of energy, and which
10 in a form OF the highest possible
usefulness to the plant. To this
class belong the compounds in the
protoplasm, the green color bodies,
and whatever surplus fond may not
have been previously conveyed away.
Tho esubstances which the plant
must needs discard are in the form of
nearly insoluble crystals and by remain.
ing In position in the leaf drop with it
to the ground and pass into that great
complex laboratory OF the soil, where
by slow methods Of disintegration use-
ful elements are sst free and once again
may be taken up by the three and
travel their devious course through
root hairs, along tho sinuous roots and
up through million celled columns of
tho trunk. out through the twigs to the
leaves once more.
The plastic substances within the
leaf, which would he lOss to tho plant
II thrown away, undergo quite dit
ferent sorios OF changes. These sub
stances arc in the EXTREMISTS parts of
tho leaf. and to pass into tho plant
body must penetrate many hundreds of
membranes of ditfusion into tho long
conducting cole 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 simple problem. These substances
contain nitrogen as part OF their com
pounds, ami as consequence are very
reaully broken down when exposed to
tho sunlight. In the living normal leaf
the green color forms q most eiTectuql
shield from the action OF the sun, hut
when the retreat is begun one of the
first steps results in the disintegrution
oil the chlorophyll. This would allow
the fierce rays OF the September sun TO
strike directly through the broad ex.
panses OF tho leaf. destroying all within,
we're not other means provided for pro-
lection. In the frat place, whom tho
chlorophyll breaks down among the re-
quilting substances formed is cyanophyll
tbluel, which absorbs the suns rays in
the same general manner aa the chloro-
phyll. In addition, the outer layers of
celia OF the leaf contain other pigments,
some of which have been niassel by
the chlorophyll, and others which ARE
formed as decomposition products, so
that tho leaf exhibits outwnrdly a
gorgeous panoply of colors 10 reds, yell
lows and hon2es that mako up the
autumnal display.
From the wild riot of tints shown by
a clump OF trees or shruhs the srroneuus
impression might he gained that the
colora arc accidental in their occur.
renee. This is far from the case, how
ever. Tho keynote Of color 10 any snecies
is constant, with minor and local yaria
tions The hirches arc golden yellow,
oaks vary through yellow orange to
reddish brown, the maple hecomos a
dark red, the tulip tree light yellow,
hawthorn anu poison oak become violet,
while tho sumacs and vines take on a
flaming scarlet. These colors exhibit
some variation in accord with the
character Of the soil on which the
plants stand.