The Laurens advertiser. (Laurens, S.C.) 1885-1973, 1897-09-28
AUTUMN LEAVES.
What Produces the Change in
Color-Why The Leaves Fali in
Autumn.

" nat Produces the Change in
Color-Why thc Leaves Fall in
Autumn.
The October number OF Harpcrs
MGgaHinh has an instructive article
from Prof. ID Il. McDOugal, in which
he explains sciGr tii1ally the changes
in color which produce oar brilliant
autumn leaves, and points out their
function in the economy Of plant life.
We make the following extracts:
The casting Of the leaf Is not Il sud
den and quick response TO any single
change IN CnViTOnmCntal conditions,
but il brought about with 4 complex
interplay OF procC sscs begun DAYS or
perhaps weeks before any external
changes are to be seen. The leaf is
IlCN IN Two classes Of substances. one
OF which is OF no further benefit to it.
and another which IL has constructed
at great cXpousC Of energy and which
is in Il form Of the highest possible
usefulness TO the plant. TO this class
belong the compounds in the prOtO-
r!es IN, the green color bodies, ard what
| ever Surplus food may not have been
previously conveyed away, The sub
stances which the plant must needs
discard are in the form 0! nearly in
soluble crystals, and Dy remaining in
position in the leaf, drop with it TO the
| ground, ard pass into that great com
! p!cX laboratory OF the soil where by
slow methods OF disintcgratiOn useful
elements are set free, anu once again
may be taken up by the tree and travel
! their devious course through root
| hairs along the sinuUus roots, and up
| through million-cclled 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
| if thrown away, undergo quite diff
fercnt series oi changes. These sub.
| stances arc in the EXTREMIST parts OF
! the leaf, and to pass into the plant
body must penetrate many hundreds
OF mem brancs by diffusion into the
long conducting cells around The ribs
or nerves, and then down into tho
twigs and stems. The successful re
treat OF this great mass Of valuable
matter is not "A simple problem. These
substances contain nitrogen as a par
Of their compounds, ana as conse
quCnce are very readily broken dowr
when exposed to the sunlight. Jn the
living normai leaf the grcon color
forms most cllGctual shield from th,
action OF the sun, but when the rCtrea
|
in the disintegratiOn OF the chloro
phyll. This would allow the fierce
rays Of the September sun to stril1,
directly through the broad cXpansc
OF the icai, destroying all within wcr
not other means provided for protcC
ton. 10 the first place, when tn
cblorophyll. breaks down, among tn
resulting substances formed is cyanC
phyll (bluC), which absOi'bs the sun
rays in the same general manner Il
the chlorophyli. In addition tn
outer layers OF cells OF the leaf cOntai
other pigments, some Of which hav
been ma kcd by the chlorophyll an
others which are formed rs dccomposi
ton products, so that the leaf exhibit
outwardly gorgeous panoply OF color
in reds, yeliows, and bronZcs tina
: make up the autumhal display. Fror
, the wild riot OF tints shown by
clump Of trees or shrubs, the crroncou
impression might be gained that tn
) colors are accidental in their Occur
: renee. This is far from the case, how
ever. The keynote OF color in an
: species is constant, with minor an
5 local variations. The birches are
7 golden yellow oaks vary through ye
} low.orange to rcddish.brown the re
2 maple becomes II Ozark red; the tulil
: tree light yellow hawthorn an
+ poison.oak become violet while th
1 sumacs and vines take on q namin
: scarlet. These colors exhibit SON
: variation IN accord with the charact,
, OF the 5or on which the plants stan
TIE plant is n most dellcatcly sci
o regulating organism. 1T cannot /
8 crease the watcr.supply, but it mi
& and does decrease the evaporating su
= face by casting or shedding the leave
It a reaction which it exhibits u 9TH
o conditions as well. Like the true Sc
Q man, however, the plant doer n
g shorten sail by cutting away its ca