424 BIOLOGY OF THE LABORATORY MOUSE 



(185, 34, 122). Ring forms occur in certain species, as well as long rods 

 segmented along their axes in a manner suggestive of division. Cultivation 

 has been successful on Noguchi's leptospira medium and on other media 

 (184, 158, 155, 142, 143, 304, 331, 333) after a period of i to 2 weeks of 

 incubation. The optimum temperature is between 25° and 28°C. Cul- 

 tivated strains may be motile. Growth has also been obtained in egg 

 embryos (304). 



In blood smears colored by Giemsa's method the organisms stain a light 

 reddish-blue color. They appear to be on or within the red blood cells 

 (Fig. 164). At the height of the infection, the majority of the cells contain 



Fig. 164. — Bartonella in the peripheral blood of a spontaneously infected, splen- 

 ectomized white mouse. (From Schilling.) 



organisms, although the number of organisms on a given cell is usually 

 small — from i to 10. Placement on the margin of the erythrocytes is com- 

 mon. Organisms have not been demonstrated in endothelial cells apart 

 from those present in phagocytized erythrocytes. The strains found in mice 

 are reported (238, 167) to be smaller and finer than the rat strains, with a 

 greater tendency to the formation of long, thin, bacillary forms. 



Schilling (238) has proposed the name Bartonella muris musculi for the 

 mouse organism to differentiate it from B. muris {B. muris ratti) of the rat. 

 Since such nomenclature becomes cumbersome and because of definite 

 differences in the human and animal bartonelloses, Tyzzer and Weinman 

 (298) have proposed two genera for bartonella organisms: Bartonella, type 

 species B. bacilliformis, to include bartonella which multiply within cells 

 (vascular endothelium) other than erythrocytes and which produce wart- 

 like or nodular cutaneous eruptions, and Haemobartonella, type species 

 H. muris, to include bartonellae in which there is no demonstrable mul- 

 tiplication outside the blood and which do not produce cutaneous eruptions. 

 The known animal strains would thus be classified in the genus Haemo- 

 bartonella. 



Eperythrozoon infection in mice. — In 1928, Schilling (237) and Dinger 

 (51) almost simultaneously discovered a new ring-like organism in the 

 blood of splenectomized mice and concluded that it differed from the 



