Evening star., 1947-04-30
W Films Show Ozone Layers
Shield Life on Earth, S Surface
concer Traced to
Woyword Evolution,
Scientists Are Told
BY Thomas R. Henry
Seisnes Editor Of The stor

Cancer was pictured as evolution
gone astray. in experiments reported
before the National Academy of Sci
ences meeting here yesterday.
Plant and animal species evolve
chiefly by mutat ations-sudden changes
in germ plasm which alter their
hereditary constitution and thence
forth are passed on from generation
to generation; Within the past few
years, means have been found of
producing these mutations in some
lower animals and plants by irradia-
ton with x-rays and ultra violet
light or by application of certain
chemicals.
All these agents are known also
to produce cancers. They are rela-
lively feeble in this respect, however,
compared with certain tar products
which are almost certain in their
effects in a short time.
Spray Produces Mutations.
DR.. M. Demerec, head of the Car
negie Institutions genetic laboratory
at Cold Spring Harbor, N. Y, used
them in the form of saturated
spray to which fruit flies are ex-
posed. These are the favorite ami
mails for evolutionary experiments
because of their variability and the
speed with which generation sue
ceeds generation. He found, as he
had expected. that they produced
mutations in the same way as did
X-ray and ultra violet radiation.
Thus, he told the National Acad-
emy, he has demonstrated that all
the mutation-produeing agents also
are cancer producers. This was
looked upon as striking demonstra-
ton of theory which has been held
for some time that cancer in the
beginning is a body cell which has
"mutated' and which henceforth
follows line of heredity different
from the normal cells with which
it is surrounded.
Supports Hypothesis.
DR.. Demerec stressed his expert
ment as giving experimental proof
Ito the hypothesis that cancer may
originate as result Of mutation
occurring in body CELL"
Practically all mutation brought
about experimentally in plants and
animals in the past have been dis
advantageous, usually leading to the
early death of the individuals. Evo-
luton requires that some of them be
advantageous, making the individual
better able to survive than the nor
NAL stock. Lack of evidence that
such mutation occur has been an
outstanding difficulty in explaining
the mechanics of evolution,
In experiments reported from the
Carnegie laboratory, Drs. Theodore
Bobzhansy and B. Spassky proceed
ed on the theory that mutations in
fruit flies brought about by the va
rious known agents, such as X-ray
irradiation, were the ones which
were easiest to bring about and that
they must have taken place many
times in nature. Since they were
disadvantageous, the stock had con-
stantly died out after a few genera
tions.
Some Mutations Beneficial.
They started with strains of fruit
flies already loaded with many disa-
bility mutations and subjected them
to X-ray irradiation to find if in
duced mutations might not also
overcome, as well as cause, disad-
vantageous traits. They studied
nearly half million flies through so
generations.
They found that they brought
about decided improvements in sew
eral OF their strains. In some, the
rate of development was greatly in
creased. The net result was the con-
clusion that mutation, shown to
produce cancer in DIR. Demerec's ex-
pertinent, also could be of decided
benefit.
At the annual dinner Of the acad-
emy at the Hotel Washington last
night, the John j. Carly gold medal
for 1947 was awarded to Prof. Ross
q. Harrison of Yale University, for
mer chairman of the National Re-
search Council here. Prof. Harrison
was one of the earliest experiment
ers in the development of the nerv-
GUS system. The award was for his
entire scientific career