ANIMAL PARASITIC INFECTIONS 413 
monkey, Brachyurus calvus, resembles P. malariae, the parasite of quartan malaria 
inman, and P. reichenowi (Sluiter, Swellengrebel, and Ihle, 1922) is said to be 
similar to P. falciparum of human estivo-autumnal malaria. 
Reichenow ! in the study of chimpanzees and gorillas in the Cameroons re- 
ported that he had found in these animals three species of Plasmodium which 
he regarded as identical with the three human species. These apes were said to 
live in the vicinity of human habitations and were liable to be bitten by infected 
mosquitoes. He says that he found forms corresponding in every way with 
P. falciparum and that the parasites in the animals are indistinguishable from 
those found in negroes. However, a number of observers were not convinced by 
Reichenow’s observations. 
The parasites of the chimpanzee have more recently been studied by Black- 
lock and Adler? in West Africa. They observed in the blood of these animals 
large amoeboid forms like those of P. vivax in enlarged and pale red cells, large 
more or less banded forms with coarse pigment like P. malariae, small ring forms 
in red cells of normal size and color resembling ring forms of P. falciparum, and 
gametocytes of crescent form indistinguishable from those of P. falciparum. 
However, no segmenting forms were seen in the blood. 
Although there is such morphological similarity, the results obtained by cross 
infection experiments suggest that host-parasite specificity among the malarial 
organisms in monkeys and man is usually rather rigid. Thus Gonder and Roden- 
waldt * attempted to inoculate two human beings with P. kochi, but the results 
were not successful. Blacklock and Adler * also made unsuccessful attempts to 
infect two human beings by subcutaneous and intravenous inoculations of blood 
from a chimpanzee infected with the parasites. In additional experiments they 
also failed to infect a young chimpanzee by inoculating human blood contain- 
ing P. falciparum. On the other hand, Mesnil and Roubaud’ have reported 
upon the successful inoculation of P. vivax in the chimpanzee. Recently Yosh- 
ino © has claimed that he could successfully inoculate puppies and guinea pigs 
with P. vivax if young animals were used. Zia and Faust‘ have attempted to 
repeat these experiments and have utilized hamsters, rabbits and guinea pigs 
which were about two months old. They also employed what they regarded as 
provocative measures consisting of splenectomy and the injection of strychnine 
nitrate a short time before or after the inoculation of the animal with infected 
human blood. The injected blood was taken from patients suffering with acute 
attacks of P. vivax or Laverania malariae infection and parasites were present in 
large numbers. The organisms were injected subcutaneously or intraperitone- 
ally but they were unable to infect any of the animals. Steinfeld * has also shown 
1 Reichenow: Centralb. Bakt. u. Parasit. (1920-1921), LXXXV, 207; Doflein’s ‘Lehrbuch der 
Protozoenkunde”’ (1929), p. 997. 7 
2 Blacklock and Adler: Ann. Trop. Med. and Parasit. (1922), XVI, 99. 
3 Gonder and Rodenwaldt: Centralb. Bakt. u. Parasit. (1910), LIV, 236. 
4 Blacklock and Adler: Loc. cit. 
5 Mesnil and Roubaud: Ann. Inst. Pasteur (1920), XXXIV, 472. 
6 Yoshino: Arch. f. Schiffs-u. Tropen-Hyg. (1926), XXX, 624. 
7 Zia and Faust: Rivista di Malariologia (1928), VII, 301. 
® Steinfeld: Arch. f. Schiffs-u. Tropen-Hyg. (1929), XX XIII, 592. 
