The Providence news. (Providence [R.I.]) 1891-1906, 1897-04-02
The Green Color of Plants.
Telephone No. s7s.

The yearly miracle of the appearance OF
innumerable shades and hues of green in
awakening vegetation exerts mysterious
Influence, amounting to "a fascination,
over the human racc-a fascination made
strong by the inherited experience Of un-
told generations Of forest dwelling ances-
tors reaching backward across the entire
present geologic period, and which grows
in intensity as we creep from the crea-
tion To the millennium.
Our vague and emotional inherited in
terest in the annual reyivification OF the
vegetable world becomes vividly intense
and direct, however, when 1T is learned
that the universal blush of green is due TO
the most important coloring substance in
the world-chlorophyl. 1t is literally true
that the existence of every living thing
on the tace of the globe is ultimately de-
pendent upon the activity of plant-green.
The action of chlorophyl may best be
understood when it's physical properties
are demonstrated. In order to do this Il
solution of the substance is obtained by
placing gramme of chopped leaves of
geranium or grass in few cubic cent?
metres of alcohol for an hour. The solu-
tion will be bright, clear green color;
and when the vessel containing it Is held
in such "a manner that the sunlight il re-
flected from the surface of the liquid, 1T
VIII appear DloOu Tctl, uue to pTOptIty
of fluorescencc-that of changing the wave
lengths of the violet end of the spectrum
in such n manner as to make them coin
eide with those of the red end 1t Is by
examination of light which has passed
through solution of chlorophyl how
ever, that the greatest insight into its
physical properties may be obtained. If
such ray is passed through a prism and
spread upon screen, 1t may be seen that
there are several intervals or dark bands
i'm the spectrum. The rays which would
have occupied these spaces have been alb
sorbed by the chlorophyi and converted
into heat and other forms. This energy Is
directly available to the protoplasm con-
tanning the cfllorophyl As u neces-
sary concomitant of its properties, ehloro-
phyl Is usually only to be found in or
gans exposed to the light Ii would be
not only useless but dangerous elsewhere,
as IL disintegrates i'm darkness into sub
stance hurtful to the organism. 1t Is
found in greatest quantity In leaves in
mis-. 1t Is not distributed throughout the
entire cell, but occurs I'm the masses of
protoplasm, which the botanist terms
chloroplasts The chloroplasts are sponge
like structures, and the chlorophyl is to
be found in solution in an oil in the in
tersticcs of the protoplasmic sponge.
Chlorophyl L. an extremely complex sub
Hence, as soon as the chemist extracts it
from the plant i'm the attempt TO make
an analysis, disntcgration sets in, and
he is no longer dealing with chlorophyl,
but with the substances derived from IL
by decomposition. Investigation upon the
nature and activity of plant-green has
been in progress more than "a century, yet
it's exact chemical composition is un-
known.
The beautiful and striking colors of
autumnal foliage are due in greater part
to the substances formed by the disnte
grafton of chorophyl The many thousand
tints of green leaves are due to a number
of causes In some instances the outer
LAYERS of the cells of the leaf or merely
the walls of the cells, may contain color
ing matter. The number and size of the
chloroplasts. and consequently the amount
of chloropbyl, may be greater in some
leaves than others. Besides the chloro-
plasts may be moved about the cell and
their distance from the surface of the leaf
altered or they may be placcd in lines
perpendicular or broadside To the surface.
In this manner the infinite and elusive
variations Of color. SO fascinating To the
lover Of nature, arc produced In vegcta-
ton. The color of the leaf may vary mo-
montarily throughout the entire day, as,
indeed, does that of tho entire landscape
before the puzzled artist.-From THE
Green Color OF Plants, by ID. T. Mac
Dougal, in Harper's Magazine for April.