Source and habitat : Found in the blood of the gray-backed deer mouse (Peromysciis mnniculatiis gracilis) . 3. Eperythrozoon dispar Brujnoghe and Vassiliadis, 1929. (Ann. de Parasitol., 7 1929, 353.) dis'par. L. adj. dispar unlike. Resembles Eperythrozoon coccoides in staining, in distribution on the erythrocytes and also in appearance, except that circular discs with solid staining centers may greatly outnumber the ring forms. Found on the red blood cells and in the plasma. Size range similar to that of Eperythrozoon coccoides; there are also some larger ring forms. Has not been cultivated. Immunology: Infection is followed by premunition, and latent infection is made manifest by splenectomy. Splenectomized rabbits premunized against E. coccoides do not react to inoculation with E. dispar; if the latter is injected first, the rabbits do not react to E. coccoides. Inf ectivity : Infective for the European vole (Arvicola (Microtus) arvalis), the Amer- ican vole {Microtus pennsylvanicus pennsyl- vanicus), the dwarf mouse {Mus minutus), the rabbit and Mus acomys. Not infective for albino rats or albino mice. Source: Recovered from the blood of in- fected animals. 4. Eperythrozoon wenjonii Adler and Ellenbogen, 1934. (Jour. Comp. Path, and Therap., 47, 1934 (Sept. 3), 220.) wen.yo'ni.i. M.L. gen. noun wenyonii of Wenyon; named for Dr. C. M. Wenyon, who studied these organisms. Morphologically similar to Eperythrozoon coccoides. Coccoid and often vesicular, staining pale red with Giemsa's stain and varying from 0.2 to 1.5 microns in diameter. Multiplication seems to be by budding, by fission and by filamentous growths from the ring forms. Up to 50 or 60 organisms are found on one red blood cell. These are ar- ranged in irregular chains or in tightly packed groups. Cultivation: Not reported. Immunology: The organism creates a state of premunition; latent infection is made manifest by splenectomy. Pathogenicity: Cattle are susceptible, but sheep are not infected either before or after splenectomy; a splenectomized pig proved non-susceptible. Source: Recovered from the blood of in- fected cattle. Habitat: Found in the blood of infected cattle; arthropod transmission has not been proved. 5. Eperythrozoon ovis Neitz et al., 1934. (Neitz, Alexander and du Toit, Ad- dress, Biological Society, Pretoria, Mar. 15, 1934; from Neitz, Onderstepoort Jour. Vet. Sci. and Anim. Ind., 9, 1937, 9.) o'vis. L. noun ovis a sheep. Delicate rings approximately 0.5 to 1.0 micron in diameter, though occasionally larger. In addition there are triangular forms with rounded angles as well as ovoid, comma, rod, dumbbell and tennis-racket forms. Found supra-cellularly on the eryth- rocytes, but often free. Colored pale purple to pinkish purple with Giemsa's stain. Sug- gested mode of multiplication is by budding. Has not been cultivated. Immunology: The immunological state in sheep appears to be that of the premunition type. Pathogenicity: Sheep, antelopes and probably goats and splenectomized calves are susceptible. Dogs, rabbits and guinea pigs are refractory, and a splenectomized pig was not infected. The distinctive feature of Eperythrozoon ovis is its ability to provoke illness in normal animals without resorting to splenectomy. Source: Found in the blood of infected sheep in South Africa and in the United States. Habitat: Occurs in the blood of infected animals. No ectoparasites found on sheep were naturally infected, but an arthropod is suspected as a vector. 6. Eperythrozoon suis Splitter, 1950. (Science, HI, 1950, 513.) su'is. L. noun sus, suis a pig. Rods, rings, coccoids and various budding forms have been reported, a ring form aver- aging 0.8 to 1.0 micron in diameter being the most common. Larger ring and discoid types
