Evening star., 1936-04-04
Life may have had a bar Of green
light to hurdle to get toe-hold on land.

Life may have had a bar of green
light to hurdle to get toe-hold on land.
At the very threshold of the living
world hitherto unsuSpected phenome-
non of the intricate partnership of light
and life has been discovered by DR..
Florence E. Meier of the Smithsonian
Institution.
This is the definite inhibiting effect
on the reproduction of the one-celled
plants known as green algae of the green
rays Of the solar spectrum. 1t may have
played an important part in the mech
anism of their evolution. A relatively
slight difference in the composition OF
sunlight a half billion years ago, when
living things were making their first
appearance, might have made a pro-
found difference in biological history.
The experiments just reported by DR..
Meier were a continuation of her efforts
to determine the precise effects OF mar
rover and narrower bands Of the solar
spectrum, even down to single wave
lengths, on such life processes as growth
and reproduction. The algae were used
in these experiments not only because
they are easy to handle, but because,
owing to the fact that they are among
the simplest of known life forms, their
reactions are easier to interpret. There
are fewer complicating factors entering
into the pattern of their existence.
This does not mean, OF course, that
the algae are very simple. An enormous
gulf separates them from the hypo-
thetical simplest beginnings Of life. Per-
haps it is a greater gulf than that be-
tween algae and the highest OF existent
organic forms.
She had determined from previous ex-
periments the optimum intensity OF light,
regardless of wave length. at which these
simple plants throve and reproduced
They normally live in shady places and
cannot endure strong light. Then the
isolated wave-length regions attained by
means of various filter devices were kept
uniformly at this optimum density. The
only exception was in the case OF day.
light, which could not be precisely regu-
lated.
The green algae are considered the
most primitive of land plants and among
the first of living things to maintain an
existence out of water For at least q
half billion years they have maintained
themselves. During all this time they
have had a significant place in the
evolving complex of terrestrial life:
There are, it Is true, one-celled plants
which belong lower in the scale OF life.
Examples of these are the red and brown
algae, some of which are found thriving
at great depths in the sea on the border
line of perpetual night. They get, at the
most, very little light. Next above them
are the familiar blue-green algae which
form the scums of the surfaces OF stag
nant bodies of water. They also can
live and thrive below the surface, where
there is an appreciable decrease in the
light intensity.
The green algae spread out on the
land. They are found today not only
on the surfaces of still water, but on
rocks and on the bark of trees. They
had to adapt their ways OF life to a
much more intense light, and the adap-
tation, it appears, was quite specific. The
species studied by DR.. Meier multlplies,
in common with the majority OF one
celled floral organisms, by cell division.
The elongated cell simply splits into
two complete organisms, which proceed
to grow to critical size and then split
again.
These one-celled plants in nutrient
solution kept In complete darkness do