Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-03-11
Hopkins Professor Advances
Novel Theory for Recon-
structing Ancient Globe.
PESTS OF PRESENT WILD
ANIMALS USED AS CHECK
DR.. Metcalf Points to Marsupials
As Proof of Southern Con-
nected Continents.
BY THOMAS r. HENRY.

| the map of teh ancient world, with 1ts
vanished continents, islands and oceans
is proposed through the Smithsonian
Institution by DR.. Maynard M. Metcal1
of Johns Hopkins University.
He would use the parasites of living
animals to rebuild picture OF the
environment of their past and record
of their migrations. This evidence. II
is pointed out. could be used as a check
| on the evidence of other sciences on the
history of the past and the evolution
of species.
Many of these parasites studied by
DR.. Metcalf are microscopic protozoans
| whose life history for millions Of yea IS
has been tied up with that of their
host animals. Everything that lives,
from man to the earthworm, Is the car
rier of parasites, but these creatures are
very selective in their hosts--one species
often injecting only one species OF
animal.
A subject of contention for many
years has been the likelihood that mil
lions of years ago there was land
connection between Australia, South
America and Maylasia, possibly a part
of the Antarctic continent which is now
being explored. There is general re-
semblance among the animals of these
three sections.
Mammal Fauna Localized.
The mammal fauna Of Australia is.
with single exception. marSupial-that
is. the young are born in an exceedingly
primitive condition and carried by the
mother in pouch. There are marsu-
pals in South America and Maylasia, but
none in the northern hemisphere, except
for one modified type. Australia has
been cut Off from mammal invasion
from the outside world for countless
centuries, so the marsupial type has re-
manned unmodified. The other two
sections have been in constant touch
with northern invasion. which have
modified the type. There are other
similarities among the birds and reptiles
This signifies to many biologists that
the fauna, at least of Australia and
southern South America, must have had
a common origin and have been able
to migrate from one continent to the
other overland The other theory Is
that he@types developed independently
due to q similar environment, or that all
originally were northern migrants
There Is geological evidence of q land
connection which is not entirely salts
factory, and the biologists have not been
able entirely to prove their point. So
the map of this part of the ancient
world has remained a mystery.
Now, says DR.. Metcalf, there are no
true frogs in either South America or
Australia except two species which are
known to be recent migrants from the
north. The place of the true frogs is
taken by the southern frogs" with
striking structural differences, which are
distributed in South and Central
America, Tasmania, Australia, Papua
the New Hebrides, the Bismarck Archi-
pelago and South Africa. Those OPP
posed to the land connection hypothesis
have advanced the theory that these
southern frogs came from the north
where they now are extinct, following
different paths south. A recent school
of BIOLOGISTS claims the probable
northern origin of all terrestrial animals
and that similar forms have undergone
parallel evolution instead OF having
a common origin.
Both Have Common Parasite.
Both the South American and Aus
tralian southern frogs, DR.. Metcali
points out, have common protozoan
parasite which is entirely absent from
the Old World except in Australia and
in the New World has extended north
only to the southern coasts OF North
America. These parasites OF the southern
frogs, he says, indicate seemingly be-
You'd question that the Australian and
American southern frogs are related
and also that they arose in the southern
hemisphere and passed by some southern
route from one to the other OF their
southern habitats. 1t might be possible,
however unlikely, that the southern
frogs of Australia evolved from very
different ancestors in a way parallel to
that of the South American southern
frogs. But no one can for moment
believe that along with the parallel
evolution of the American and the
Australian hosts there was also a par
allel evolution of their opalinids to
such a degree that almost or quite
Identical species of parasites are found
in these frogs In South America ana
Australia"
Most geological geographers. he points
out, have postulated both an eastern
and western southern land connection,
although some have reconstructed the
ancient map with great northern lana
mass, Arctogea, where most life orlgl-
mated and from which 1t was dispersed
south by the Isthmus OF Panama to
South America, by way OF the Maylasian
Islands to New Guinea, Australia and
New Zealand, and by way OF the Isthmus
of Suez to Africa. Arctogea would have
been comprised of most of the land
mass of Europe, Asia and North Am
erica. with northern land connections
There is no evidence, he says, that
| the southern frogs ever existed in this
| hypothetical ArctOgea. At least they
are not there today, and this particular
protozoan parasite also has disappeared
completely. Now the southern frog
! 1t is nearer the toads than the frogs
shares the parasite with other southern
toads. It is reasonable to believe that
| If these amphibians ever were In
| Arctogea these parasites would have
1 spread to the other toads which are
| still living there. The disappearance OF
both from the north and their sinful
taneous temperance In the south, he
believes. would be too great a CO.
| incidence.
Thread validates Evidence.
Thus, such a slender shred Of evidence
as the minute parasite OF toad ap'
parently validates the picture Of van
ished lands in the far distant past
DR.. Metcalf even is able to date roughly
the geological picture. Thus there are
more southern frogs in South Americs
than in Australia and they are more
diversified. This indicated that they
originated in the western continent OF
in Antarctica and migrated to Australia
But there also are lots of true toads ir
South America and none IN Australia