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Dogs, cats and certain other carnivores are the hosts of a coccidium of the family Eimeriidae known as lsospora bigemina (Stiles, 1892) (Fig. l). This Isospora has three outstanding and peculiar characteristics: (1) Its endogenous development takes place in the lamina propria or cores of the villi of the small intestine of its host in chronic infections, but in acute infections it may colonize the epithelial cells of the entire small intestine: (vide Wen yon, 1926, and Wen yon and Sheather, 1925) ; (2) Its oocysts sporulate completely in situ when occurring subepithelially and are passed in the fully developed condition, but in scanty numbers; (3) The oocyst wall, which contains the two spores, is thin, sometimes so thin it seems to be absent altogether, and is stretched, or even slightly constricted between the spores, so that the term "accordion-like" has come to be applied to the "bigeminal" figure so created; (4) The spores, with comparatively thick walls, are often found singly and free in the feces, usually along with the bigeminal oocysts. Finck (1854) first saw this species and described the sporulated oocysts (corpuscules géminés) as he saw them inside the villi of the cat's intestine, though he failed to interpret them as microorganisms. Stiles (1891, 1892), an American working in a laboratory in France" described the species on the basis of the bigeminal nature of its oocysts and their position in the villi of the dog's intestine.

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Proceedings of the Iowa Academy of Science





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©1954 Iowa Academy of Science, Inc.



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