(1973) n°3 - Royal Academy for Overseas Sciences

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colleagues in order to see if the exoerythrocytic stages differed
from those of the ordinary type. This work was done by infecting
mosquitoes on patients with P.v. hibernans malaria,
and inoculating the sporozoites into splenectomised chimpanzees.
The observations are not complete, but reveal so far no
differences in the tissue stages.
Rodent Malaria
I should like to refer briefly to the malaria parasites of
other mammals, because those of rodents are of exceptional
interest. Plasmodium berghei was found ;în 1948 in the Belgian
Congo by V in c k e and L ip s, in Grammomys surdaster. This
was one of the most important discoveries in the history of
malaria, because it provided a tool for malaria research of incomparable
value. Naturally, every effort was made to elucidate
the full life cycle of the parasite, but this proved very
difficult. At last, in 1965, Y o e l i visited the forests of the
Haut-Katanga with his Belgian colleagues, observed the low
temperature which prevailed, and finally dropped the temperature
of his insectaries in New York from 28° C. to 18° C. Mosquitoes
then became heavily infected; the sporozoites were injected
into hamsters and exoerythrocytic schizogony was shown to
be complete in 48 hours! The site was again found to be the
parenchyma cells of the liver.
Hepatocystis Spp.
The tissue stages of a great variety of species of Hepatocystis
and other haemoproteids have also been discovered since 1947.
I might just refer to one instance, because R o d h a in and I in
the same year (1953) both found the exoerythrocytic schizonts
of H. epomophori in fruit bats in tropical Africa, he in the
Congo (where in 1926 he had originally described the parasite
as Plasmodium epomophort) and I in Kenya.
Relapses
At the beginning of this paper I said that I wanted to draw
attention to some lacunae in our subject. The chief one is the