Evening star., 1939-09-12
Of Stars, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
BIZ Thomas r. Henri.

By Thomas r. Henry.
Blue and violet light stunts the growth
Of plants by bringing about a decrease
In their normal growth substances.
Determination of this, which has puz-
Zled plant Psychologists ever since the
different effects on plant growth Of
different colored lights first was discov-
cred about 20 years ago, has just been
announced by DR.. George w. Popp, pro-
fessor Of botany at Pennsylvania State
College.
Plants were grown in darkness and
some of them given daily irradiations
from mercury vapor lamp. In few
days the irradiated plants were greatly
stunted. These plants, along with the
untreated plants which had been kept in
the dark, were now tested chemically
for the presence of growth substances.
Some 5000 tests were completed and In
every case the irradiated plants had
much less growth substance present.
Plants exposed only to the range Of
ultraviolet present in daylight, or only
to visible light, likewise had less growth
substance than untreated plants in the
dark. Plants grown in red-yellow light,
however, had almost as much of the
plant hormone materials as did those
grown in the dark.
Since the hormones accelerate growth
in length these results indicated that
the stunting effect of ultraviolet and
blue violet radiation was brought about
through their reduction.
Experiments by other workers, in
which the hormones were allowed to
diffuse out of the plants and were then
irradiated by a mercury vapor lamp,
show that the violet end of the spec
trum produces its results by destroying
the power of the growth substances.
Thus plants grow taller in red light
because such light apparently does not
destroy the hormones
The hormones occur, DR.. Popp points
out, in extremely minute amounts. In
this respect, those in plants are similar
to those In animals. In the human
body, for example, there is present at
one time only one-fourth of a grain of
complete imbecility of the individual
The substances are present in such
minute quantities that they are not re-
vealed by ordinary chemical tests. A
living organism, however, will often re-
act to as little as one part in 10000 900
parts of water.
The condition in plants apparently is
very similar, DR.. Popp points out. How
ever minute the amounts OF the hor-
mones, they are indispensable and their
absence produces striking growth varia-
tions.
A new practical use for lignin. one of
the most abundant agricultural waste
products in the country, has been dis
covered by Department of Agriculture
chemists at the Agricultural By-Products
Laboratory at Ames, Iowa.
1t is. they found, the best agent for
removal of iron from water. Few cities
have water sufficiently pure that 1t does
not require treatment for removing this
element. Iron in small quantities, even
as low as Is parts per 1000 900, causes
water to discolor clothes in home wash
ings.
Supplies OF lignin are inexpensive be-
cause they are almost limitless. Roughly
one-fourth of all wood is lignin. AS a
waste product of wood pulp mills, where
its disposal pollutes streams, it amounts
to 100000 tons each year. At least
100000 tons year are available from
cornstalks and an equal quantity from
wheat straw.
In treating water that contained about
SO parts per 100000 of iron with 500
parts per 100000 of lignin, the iron
content was reduced to about two-tenths
of part per 100000 The lignin was
recovered and used over again as many
as 10 times with no appreciable lessen
ing of efficiency.
Many cities may find it possible to use
lignin treatment with existing water
filtration plants by adding the recov-
cred lignin to the water in the mixing
and sedimentation tanks, or applying
it as the water enters the filters, where
carbons are used for odor removal
The stinger of mosquito weighs
.OOOOO6 of an ounce. A printed period
tips the scales at 100000 of gram, while
a comma is more than twice as heavy
with an average weight of .OOOOO5 of a
gram An exclamation point weighs
.00O008 of a gram.
These ultrafine weight determinations
are announced by DR.. Harry F.. Miller.
microscopy specialist of the General
Electric Co. They were obtained with a
microchemical balance.
He found that one of his own eve
lashes weighed 00OOol7 of an ounce and
grain of sugar .00OO068 of an ounce.
There would be approximately 2 360 nn0