The chimpanzee displays a natural resistance to the blood forms of Plasmodium ovale but allows multiplication and growth of this phase when splenectomized.
The tissue phase of P. ovale is able to grow and reproduce normally in chimpanzee liver and persists there for at least 39 days. The natural resistance of the chimpanzee to the blood phase is without effect upon the tissue phase of P. ovale.
P. ovale is unchanged on passage through chimpanzees and is able to infect man following two chimpanzee-mosquito passages.
Anopheles gambiae is established as an efficient vector of P. ovale.
Schizonts of P. ovale in liver pieces of a chimpanzee taken 7, 18 and 39 days after infection with sporozoites are described and discussed.