Evening star., 1942-07-28
Of Stors, Men
And Atoms =
Notebook Of Science Progress
In Laboratory, Field
And Study
By Thomas r. Henry.

An hitherto unknown natural phe-
nomenon-probable wholesale vaccina-
ton Of population against q deadly
malady by mosquitoes-has been reported
to the American Medical Association.
Up to now these insects have been con-
sidered only as carriers OF disease.
Sporadically during the past decade
there have been outbreaks among
American horses of an often deadly
disease-equine encephalitis It is very
similar to- If not identical with, human
encephalitis OF the type which ravaged
st. Louis few years ago.
Once recovered from an attack an
animal develops strong immunity to
another infection. This can be demon
strated by finding antibodies in the blood.
But when Drs. w. M. Harmon, B. H.
Carle and E. M. Izumi OF the University
OF California tested large number OF
horses and other animals on the Pacific
Coast they found that 10 per cent OF
them had these antibodies without ever
having had the disease At the same
time they had not been vaccinated
against it.
At least one way the disease is spread.
1t now Is known, is by mosquitoes From
one species OF Western mosquitoes the
deadly virus can be isolated In appre-
ciable amounts.
The University OF California physi-
clans brought in some wild, unbroken
colts from an uninhabited mountain re-
gion of Nevada. They never had had an
opportunity to come in contact with the
disease and their blood showed no anti
bodies. They were inoculated with the
virus obtained from the insects.
None Of them were sick. 50 far as
could be detected. But all OF them de-
veloped sufficient protective bodies in
their bloodstreams to safeguard them
against developing the malady. The
same virus produced typical encephalitis
when injected into the brains of mice.
The conclusion is clear, it is believed.
that the horses were actually vaccinated
by the mosquito virus, which apparently
is just below the virulence necessary to
produce an attack of the malady. The
same thing, the physicians believe, hap
pens in nature.
The bites of virus-carrying MOSQUITOES
actually constitute vaccination. The
insects quickly vaccinate all the suscepti-
BILE animals in danger area and thus
prevent great epidemics. This appar-
emily is new sort of protection de-
vised by nature to protect higher forms
of life.
Whether there is any similar phe-
nomenon among human beings is un-
known. 1t long has been recognized,
however, that thousands who have never
consciously suffered from the maladies
are immune because of protective anti
bodies against both encephalitis and
poliomyelitis in the blood. It ALWAYS
has been assumed that they have SUI
fered subclnical attacks at some time
or other. But they also may have been
vaccinated by mosquitoes.
X Il
At least two plants known nowhere
else on earth are found on the remote.
rather desolate Midway Islands. out
post OF the Hawaiian archipelago, to-
which American forces have clung 80
desperately in the face OF repeated Japa-
nese attacks, according to botanists OF
the Smithsonian Institution.
One Of these is a variety of mint.
Once 1t formed part OF the rather
luxuriant plant cover Of Laysan, a small.
uninhabited island about one third the
way between Midway and the Hawaiian
Islands. In 1908 some rabbits accidently
Were infroH,1cod ~, r oysor Tr N ,~.~-
they had multiplied into thousands.
They exterminated all the plants and
reduced the island Of about square
miles into a sandy desert.
On Midway also grows a species of
nightshade-of the general deadly night
shade potato tomato family, which
otherwise is found only on the small
neighboring Ocean Island. The vege-
tation on both the Midway Islands
Sand and Eastern-is very poor. Only
20 kinds Of native plants have been
found there, the Smithsonian botanists
say. The islands are among the most
recent bits OF the earth to emerge from
the sea and afford an interesting ex-
ample OF the tendency Of life to MI
every possible spot and turn 1t into
q suitable habitat.
Seeds Of plants could have been
brought there only in two ways-by
ocean currents or by birds. The hkeli-
hood OF wind-borne seeds travelling so
far are remote. Yet the plants have
been able to establish foothold with
out human agency They die and make
SOIL which provides habitat for still
more plants.