Evening star., 1951-12-05
Gorden Tomato Crossed
With Wild Peru Plant
Healthier Strains Possible
By Biological Achievement

T1SuItHI6T SITOINS TOSSlDI6
By Biological Achievement
By Thomas R. Henry
cross between the garden tomato
and close relative Of It's possible wild
ancestor-an almost impossible biologi-
cal achievement which may result In
more vigorous and healthier strains Of
the domestic vegetable-has Just been
reported to the National Academy Of
Sciences here by DR.. Charles M. Rick
OF the University OF California.
Both parents Of the new hybrid belong
to the nightshade family of plants which
includes not only the tomato, potato and
eggplant but the deadly nightshade
ana other highly poisonous members of
the vegetable kingdom. Most of the wild
nightshades are. in fact, poisonous.
The remarkable part of the present
experiment is that the garden tomato
and the wild flower from Peru, were
members OF different plant genuses be-
tween which a cross presumably was
impossible. At first glance it would
seem almost as marvellous as cross
between tomato and a potato, all
though there actually were closer re-
semblances between the Andean flower
and the tomato than between most other
groups in the nightshade family. The
paternal plant of the combination was
obtained on University of California
expedition to the Andes in 1912.
Resort to Operation.
When pollen from plants grown from
these seeds was applied to tomato
flowers small fruits resulted in which a
few seeds developed. These, however,
did not sprout. The University Of Cali
fornia botanists then resorted to kind
OF CaeSarian operation in which the
embryo elements were removed at a
stage before seed formation and de-
veloped in laboratory culture. This
resulted in the actual production Of
plants which have shown greater growth
vigor than either parent.
But the fertility of these hybrids was
extremely low. as was expected from the
fact that they represented crosses of
two supposedly uncrossable groups Of
quite different genetic constition. This
difficulty has been overcome, DR.. Rick
reports to the National Academy. by
treatment with colchichine, the drug
now used widely in agricultural expert
mentS to produce new species. This has
made possible backcrosses with garden
tomatoes which grow with great vigor.
Most OF the characteristics of the crosses
are those OF the nightshade The vigor-
GUS growth comes from the wild par
ents. as does apparent immunity from
some devastating tomato diseases.
Scientifically the experiment is note
worthy in the annals of plant breeding.
Practical results wait on future Develop
ments. It is not known, for example,
whether the fruits may not contain dan
gerous poisonS.
A double vaccine, giving protection
against both smallpox and yellow fever
and administered by simple scratch
on the skin, has been developed by
Rockefeller Foundation scientists.
Hitherto yellow fever vaccine has been
administered by injection. Hundreds
OF thousands Of American soldiers des-
tined for yellow fever areas got such
knocks" before leaving the United
States in the last war. The vaccine was
obtained by incubation of eggs, in
which the chicken embryo was begin
ming to form, with the disease virus.
An older form. more expensive and with
certain disadvantages, was produced by
incubation of mouse brains.
The new technique started at the
Pasteur Institute at Dakar, West Africa.
where efforts had been under way for
some years to protect the entire popu-
lation. More than 2 million natives
had been vaccinated by injection. The
results were excellent but the cost was
excessively high. The Pasteur Institute
doctors found that the mouse brain
vaccine could be prepared in such a way
that it could be administered by the
scratch technique, long familiar in
smallpox vaccinations. The two vac
cnes. in fact, could be mixed and given
In the same dose.
Easier and Cheaper.
The method was so much easier and
cheaper that now more than 20 million
nave been given the double vaccination
In French African colonies. But this
DIDN'T work with the chick embryo
vaccine. While the French double vaccine
gave excellent protection there were
serious drawbacks. Some of the reactions
were very severe, especially among per-
sons doing hard physical labor. The use
OF an animal tissue, such as mouse brain,
involved the risk of transmitting other
virus diseases known to infect mice.
Among these was choriomeningitis, a
relatively mild form of meningitis due
to filterable virus.
After a long series Of experiments.
it Is announced, the Rockefeller Founda-
ton scientists now have worked out a
method by which the chick embryo
vaccine. completely sterile of other
organisms, can be prepared SO that it
can be administered effectively by the
scratch method and combined with the
smallpox vaccine.
The cost OF both production and adj
ministration is greatly reduced-thus
constituting a major practical victory
in the fight for the elimination Of
yellow fever from the world.
Questions and Answers