SPOROZOA 465 



Plasmodium immaculatum and falciparum 



This type of malaria is usually tropical. It is malignant, 

 and does not yield readily to treatment. Two types are known, 

 a quotidian, which completes its asexual cycle in twenty-four 

 hours, and a tertian, which requires forty-eight. Whether or not 

 these are distinct species is uncertain, but is probable. 



THE GENERA PROTEOSOMA, HALTERIDIUM, AND HEMOPROTEUS 



These are genera of sporozoa which produce a malaria-like 

 infection in birds. In some forms a part of the life-cycle is also 

 spent in the body of the mosquito in this case a Culex. None of 

 the species are of any considerable economic importance. 



THE GENUS ANAPLASMA 



This genus was created by Theiler in 1910 to accommodate the 

 organism described as " marginal points " in the erythrocytes 

 of cattle. The protozoan consists of a tiny dot of chromatin- 

 like material in the corpuscle, usually near the margin, never 

 more than one-thirtieth to one-twentieth the size of the cell. 

 The name Anaplasma comes from the apparent lack of any cyto- 

 plasmic material. 



Anaplasma marginale 



Synonym. Marginal points. 



Disease Produced. Anaplasmosis, Galziekte, or gall sickness 

 in cattle. 



This organism, according to Theiler, has been observed by 

 several investigators, among them Smith and Kilborne, in their 

 study of Texas fever. These observers have believed it to be a 

 developmental stage of the Piroplasma (Babesia) bigeminum. 

 Theiler has succeeded in demonstrating the distinction between 

 the organisms, and defines Texas fever as a mixed infection of 

 Anaplasma marginale and Piroplasma bigeminum. 



Distribution. Known with certainty from South Africa, prob- 

 ably widely distributed. 



Morphology and Staining. The organism may be single in the 

 corpuscles, or there may be several within a single cell. The para- 

 sites usually lie near the periphery of the corpuscle, rarely free 



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