Evening star., 1941-01-30
Of Stars, Men
And Atoms
Notebook Of Science Progress
In Laboratory, Field
And Study
BIZ Thomas r. Henry.

invisible ultraviolet light of the sun.
In some manner, more than half
billion years ago. higher forms of life
rose from primeval, one-celled plants
and. animals of the sea slime, partly
under the influence of sunshine. Ex-
periments just reported by Mrs. Flor
ton biologist, deal with some of the
basic processes in the growth of this
great tree of life on earth
Mrs. Chase exposed green algae, one
celled plants which are among the most
primitive forms of life on earth, to
specific wave lengths of the invisible
radiation of sunlight. In previous ex-
periments she has shown that prolonged
exposures of these delicate organisms,
countless billions of which constitute
the green scum on stagnant water, to
ultraviolet were fatal. Specific wave
lengths, however, varied greatly in their
lethal powers Ultraviolet now Is we'll
known as germ killer. Hospital oper
ating rooms are given baths of 1t to
The new findings are that when the
one-celled organisms are exposed to
certain wave lengths for about two
thirds of the time necessary to kill them
the effect is quite the opposite. The
colonies are stimulated to extraordinary
growth. Like most other single -celled
organisms they reproduce by splitting in
two, each cell becoming two individuals.
Her experiments show vividly the ex-
treme specincity Of single wave lengths
which occur in the ultraviolet band of
the solar spectrum. She used four of
them in different tests. One stimulated
the algae culture to growth Al times
that Of similar culture which was not
irradiated. Exposure to the same amount
of radiation of another wave length
produced growth 80 times greater
than that of the controlled. Another
brought a 4!65 fold growth The fourth
and longest wave length used stimulated
increase only 162 times that of a cul-
ture that had not been irradiated.
The individuals of the stimulated cul-
lures, Mrs Chase's measurements
showed, grew smaller and smaller with
successive irradiations, compared with
the normal size of such algae. Thus,
eventually, the total sizes OF the stim-
ulated populations became smaller than
those of the unstimulated, although they
consisted of vastly more individuals.
This introduces. the experimenter
points out, fundamental problem in
biology. 1t might be assumed that the
acceleration of growth with a sublethal
dose of ultraviolet was due to a basic
process of evolution. The weaker indi-
viduals would be killed and the stronger,
harder ones pushed to the fore.
But the fact that the algae actually
become weaker while multiplying faster
at the same time indicates that some
deep-seated change may have taken
place in the organism itself-perhaps
the production Of a new species.
The atmosphere of Mars, above each
square foot of the planets surface, con-
tains less than one-twentieth as much
water vapor as does that of the earth,
which has about two-tenths OF one
per cent Of this gas.
Such Is the conclusion of DR.. Walter
S. Adams, director of the Mount Wilson
Observatory of the Carnegie Institution
of Washington, from the most exact
spectroscopic observations yet made on
the earth's neighboring planet.
Mars shines entirely with reflected
sunlight. Before this light is observed 1t
| must pass through several miles of the
earth's atmosphere. Consequently it has
been extremely difficult to study any diff
ferences between its spectrum and that
Of direct sunlight received on the earth's
surface. The spectrum shows the effects
on light of passing through water vapor
DR.. Adams, working with the most
delicate spectroscope yet known, made
his measurements both when the planet
was approaching the earth and reced-
ing from it. This motion tends to sep
arate lines due to any water vapor in
the spectrum of Mars from those formed
in the earth's atmosphere. These lines
would be on the violet side of the earth S
lines when Mars is approaching and on
the red side when 1t is receding.
IL audHlS uledSuT eIIlenCS also con.
firm earlier conclusions that Mars has
extremely little, If any, free oxygen, In
spite of the vast amounts which may
have been combined with its rocks. It
is practically certain that no free hydro
gen, the lightest Of gases and the other
constituent Of water vapor, can be
present
Confirmation of the extreme dryness
of the Martian atmosphere-far too dry,
1t is likely, to permit the existence of
most forms of life known on earth
leaves as much of a mystery as ever the
nature of the supposed polar ice caps"
on the planet. These can be seen to
advance in the Martian winters and re-
cede in the Martian summers.
Even if they are frozen water, how
ever, the entire water content cannot
be large, and their influence on the gen.
eral atmosphere of the planet must be
| slight.
The characteristic red color of Mars
is believed to be due to combination of
the once-free oxygen Of its atmosphere
with the rocks, possibly containing
large amounts Of iron, on its surface.
Quotes Justices