Evening star., 1940-09-10
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
By Thomas r. Henry.

By Thomas r. Henry.
A ghostly red aura envelops nature.
If human eyes suddenly should become
green-blind summer fields and forests
would seem to be surrounded with a
pulsating, unearthly flame.
This strange phenomenon now is
visible only with special instruments
Otherwise the red light is completely
drowned by the green reflection OF
leaves. 1t Is stressed in experiments
| just reported by Drs. E. D. McAlister
and Jack Myers Of the Smithsonian
Institutions Division of Radiation and
Organisms, which is investigating the
complex relationships of light to the
life Of plants and animals.
Basic TO life is the process Of photo
synthesis. The green plant is able
to absorb the energy of sunlight by
means of green coloring material.
chlorophyll, and use this energy to make
Starches and sugars out Of the HYDRO
gen Of the water absorbed by its roots
and the carbon dioxide which it breathes
from the atmosphere. This is RESPONSE
BILE for the growth of the plant. 1t
stores the energy OF sunshine Animals,
including man, eat this canned SUM-
shine. 1t Is burned, millennums later,
as coal and oil. But not all the energy
OF the absorbed sunshine Is turned into
starches and sugars. Some is radiated
in the form OF heat. Some apparently
comes out in the form of fiuorescence.
The chlorophyl molecule Is set in yibra-
ton. causing the emission of visible
hght-but of different wave length
from the light originally absorbed. In
the case Of plants it is in the red wave
length band and is extremely faint. ONLY
about tenth of ! per cent of the abb
Sorbed light is transformed in this wav.
The ghostly red light could be visible
to the eyes only of some hypothetical
race whose retinas were insensitive TO
green radiation. 1t can be brought out
by the use of filters excluding all the
green. If the eyes should become green
blind the face of nature would not be
colorless, but grass and foliage would
appear fantastic beyond all imagination.
-N RiASAoAiici1Oii VI lIuOItSCeilCe III
plants has been known for some time.
but in the past 1t has been impossible
10 study its relation to the basic process
Of photosynthesis This was made possi-
bic by the invention by Dr. McAlister
OF an extremely sensitive device by which
the rate at which carbon dioxide is
ABSORBED from the atmosphere under
various conditions of
served Immediately. Changes In fuor-
escence can be measured as rapidly as
changes in photosynthesis The abb
sorption of this gas which is one of the
ingredients Of the photosynthetic pro-
cess, becomes measure of the process
itself. BY other instruments they were
able simultaneously to measure the
degree of fiuorescence.
The process of building up hydrocar-
bons by photosynthesis, it had been de-
termined by other experiments with DR..
McAlister's apparatus, can be varied
greatly by changes in the illumination
OF green leaves or by variations in the
carbon d1oxide in the atmosphere. When
anything is done to increase notably
the rate OF this process, they report
there is a sudden burst" of the red
fuorescence, as if dead Goals had been
famed into life.
Thus, they find, when intense light is
flashed on a plant which has been kent
IN the dark there is an instant burst
OF fiuorescense to about its normal
value, followed by slow rise of about a
second to an intensity about three times
this normal for a constantly illuminated
plant. The simultaneously observed
curve for carbon dioxide assimilation is
almost exactly the reverse of this.
This f1uorescence phenomenon, the
Smithsonian scientists found, demon
strates with some plants a reverse photo
synthesis, natural curb placed by ma
ture on carbohydrate formation and
growth. This is true especially, they
found, for young wheat under normal
growing conditions 1t is, they say.
reaction of large proportions opposing
photosynthesis by always depressing the
rate OF carbon dioxide assimilation under
normal growing conditions.
The wheat plant, they found, has a
red flash, the cause of which cannot
be determined at present, about one min
ute after the first burst of f1uoresence
after light is turned on Simultaneously
there is notable decrease in the carbon
dioxide breathed from the air.
The fuorescence variations are signifi-
cant as an hitherto unknown phenome-
non OF nature, basic in the life process,
but they appear to be extremely COM
plex. probably differing for different
types of plants, and any practical appli-
cation remains to be determined.