Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-10-18

insect nor plant lives there, and the
observers haul all the water required
Tor housekeeping from the town IL
miles away. It rains scarcely an inch
century there, and they observe the sun
almost every day in the year 70 see ii
the intensity Of his rays, on which 50
much depends, Is changing. It does
change through range Of several pet
cent. Our measurements are laying 4
basis to solve the question: How much
does the weather depend on these
changes in the sun?
This Summer we have started q new
work at the Smithsonian. It Is to study
the effect Of rays on plants. As q boy
I used to suppose that plants grow and
store up woody fiber because they suck
up the material from the soil. It Is
true that they do need water and some
soil chemicals that they get that way,
but strangely enough plants obtain
from the air almost all the food that
increases their dry weight. Through
millions of mouths in their leaves they
suck In the carborfc acid gas, 30 fatal
10 animals If in excess, but which ID the
principal food Of plants. The air con-
tains only a fortieth part of l per cent
of this gas, but that mere trace is IN
dispensahle to all life. without 1t
plants could not grow and without
plants animals would starve.
Yet it is not enough to surround the
plants with air They can absorb Its
carbonic acid gas only under thu infu-
ence of light. Light differs in its ef-
fects upon them. Everybody who has
admired q rainbow knows That when
sunlight shines upon q spray OF water
the white light breaks up into band
of colors These run through violet,
indigo, blue, green. yellow and orange,
to red. Green light seems like dark"
ness to the plant. It promotes no
growth. Blue, indigo and violet. and TO
q lesser extent orange and red rays, are
able to set up a matchleSs chemistry
in the living plant leaves. Thereby the
simple molecules of water and carbofiic
acid are converted into the highly COM
pick molecules which life requires.
Regulate Temperature.
As yet, no man has initiated this life
chemistry of radiation. At the Smith
sonian Institution we shall first grow
some of the well known valuable plants
in closed chambers, within which we
shall regulate the temperature. the
the carbonic acid gas and
the chemicals at the roots. With these
variables controlled, we shall supply
radiation from special electric lamps,
and measure and regulate the exact
colors or wave lengths and the exact
lntensitieS of the rays required to pro-
mote growth. The results as regards
stature. leaf area, poisoning, seeding
and gain of dry weight, will be fundA~
mental data such as the world has long
waited for.
This is only the more superficial part
Of the investigation. We hope to de"
- IAkA
mine the structures OF the complex
molecules which constitute the sub
stance of live plants. These methods
will measure the selective absorption Of
certain rays in the spectrum by the spe-
cial groups of atoms which are the
bricks, as it were. out of which the
highly complicated organic molecules
hundreds of atoms are Curl
ously built. Proceeding along these
lines, , we hope at
length to find out what happens, and
10 learn to initiate the reactions which
light, water and carbonic acid propa-
gate in live plants. New laboratories
n the basement of the Smithsonian
here at Washington are being
equipped for the work by my colleague,
DR.. Bracket.
Others Are at Work.
Other investigators are working in
his field. At the Boyce Thompson
laboratory, In Yonkers, N. Y, they
nave been trying experiments with
lights Of different colors and different
htensities and different intervals Of
light and darkness for several years.
Or. Garner of the Agricultural Depart
nent at Washington is a pioneer in
the plants into long-day
and short-day groups. Curiously
enough, some plants blossom and seed
only while the days are short, and
merely grow to leaves and stature In
ong l1oured Summertime. Other
plants are exactly opposite In habit,
and can only blossom and seed II the
lays are long.
There are the sun-lovir1g plants like
the flasturtium and s1nflower that bend
their heads to follow the suns course
from morning till night. other plants