PLASMODIUM. 



287 



239. Plasmodium semnopitheci Knowles. (Fig. 137.) 



■^Plasmodium semnopitheci, Knowles, 1919, pp. 195-202, pis. xvi- 



xix. 

 Plasjnodium semnopitheci, Miihlens, 1921, pp. 1614—15. 

 ■^Plasmodium sp., Chimisso, 1922, pp. 38-54. 

 Plasmodium, semnopitheci, Wenyon, 1926, pp. 972, 1363. 

 ■^Plasmodium semnopithecus, Scott, 1926, p. 237 ; Knowles, 1928, 

 p. 439. 

 Plasmodium semnopithecus, Reichenow, 1929, p. 1008 ; Sinton & 

 Mulligan, 1933, pp. 382-6, 423-4; Coatney & Roudabush, 

 1936, p. 340. 



Young trophozoite an almost non-pigmented ring. Growing 

 trophozoites large flimsy rings with very large vacuole, very 

 abundant pigment, little amoeboid movement, and single, 

 oval or rod- shaped chromatin mass. Absence of segmenting 

 forms in the peripheral blood. Decolorization of infected 

 Ted corpuscles frequently observed, but stippHng never seen. 

 Gametocytes rounded. Female gametocytes often free, and 

 larger than normal red corpuscles ; chromatin small, deeply 

 staining, oval or much elongated ; pigment very dark brown, 



A B C D 



Fig. 137. — Plasmodium semnopitheci Knowles. A, ring-form ; B, larger 

 and more flimsy ring ; C, extracellular form impinging 

 against a corpuscle ; D, gametocyte. (After Knowles.) 



very abundant, and in very fine granules or small dark collec- 

 tions. Male gametocytes smaller than female gametocytes, 

 and with very large pink nuclei. 



Remarks. — Knowles (1919) discovered this parasite during 

 ^n experiment conducted for the purpose of transmitting the 

 mahgnant tertian parasite of man to a monkey. The shock 

 of the operation and the injection of foreign blood were beheved 

 to have stimulated a latent infection of a species peculiar 

 -to the host, which suddenly became virulent and proved fatal. 

 Nearly every corpuscle was found infected, and there were 

 inumerable free forms, some of them undergoing schizogony 

 whilst still extracellular. Wenyon (1926) thinks this due 

 to intensity of infection and to examination after death : 

 he considered the parasite to be very similar to P. inui, and 

 Reichenow (1929) thought that it was probably identical with 

 it. Sinton and Mulligan (1932 a) consider it noteworthy 

 -that, except for Donovan's undescribed parasite, the only 



