502 PROTOZOOLOGY 



According to O'Roke, the vector is a black fly, Simulium venustum, 

 in which the sexual reproduction takes place. Gametocytes develop 

 into mature gametes in 1-2 minutes after blood is obtained from an 

 infected duck; macrogametes about 8m in diameter; 4-8 micro- 

 gametes, 15.7-24. 1/i long, from a single microgametocyte; zygotes 

 are found in stomach contents of fly in 10-20 minutes after sucking 

 in the infected blood cf bird; motile ookinetes abundant after 5 hours, 

 measure 33.3)u by 3-4. 6m; 22 hours after sucking duck blood, oocysts 

 are found on outer wall of stcmach; sporozoites mature probably in 

 24-48 hours; 5 days after a duck has been bitten by infected black 

 flies, schizogonic stages are noticed in endothelial cells of capillaries 

 of lungs, liver, spleen; on about 7th day gametocytes appear in blood ; 

 liver and spleen become hypertrophied; the infection among duck- 

 lings is said to be highly fatal and appears often suddenly. 



Mathis and Leger: Macrogametocytes, oval; 14-15m by 4.5-5.5m; 

 several vacuoles in darkly stained cytoplasm. Microgametocytes, 

 oval; slightly smaller; cytoplasm stains less deeply. Infected host 

 cells about 48m long; nucleus elongate. 



Huff found that (1) young schizonts are in macrophages of, and 

 also extracellularly in, the spleen and hver; (2) two types of schi- 

 zonts occur: one, "hepatic schizonts" in hepatic cells which cause 

 no distortion or alteration of the host cell, and the other, "megalo- 

 schizonts" in the blood vessels of, or extravascularly in, the heart, 

 spleen, hver and intestine; (3) megaloschizonts become divided into 

 many cytomeres which give rise to numerous merozoites; (4) young 

 gametocytes occur in lymphocytes, monocytes, myelocytes and late 

 polychromatophile erythrc blasts; (5) the cells in which fully grown 

 gametocytes occur, appear to be macrophages. 



Family 3 Babesiidae Poche 



Minute non-pigmented parasites of the erythrocytes of various 

 mammals; transmission by ticks. 



Genus Babesia Starcovici {Piroplasma Patton). In erythrocytes of 

 cattle; pear-shaped, arranged in couples; sexual reproduction in fe- 

 male ticks in which developing ova, hence young ticks, become in- 

 fected with ookinetes, producing sporozoites which enter salivary 

 glands (Dennis). 



B. higemina (Smith and Kilbourne) (Figs. 235; 236, a-d). The 

 causative organism of the haemoglobinuric fever, Texas fever or 

 red-water fever of cattle; the very first demonstration that an ar- 

 thropod plays an important role in the transmission of a protozoan 

 parasite; the infected cattle contain in their erythrocytes oval or 



