1. Bartonella muris has been isolated in pure culture on Noguchi's leptospira medium from the blood of the splenectomized adult rat suffering with Bartonella muris anemia.
2. Bartonella muris is a small, actively motile, Gram-negative bacillus. It grows best on media containing blood and on Noguchi's leptospira medium. The optimal temperature for growth is 20–25°C. It produces neither gas nor acid on media containing sugars. It does not hemolyze blood in artificial media. Viability of the cultures in leptospira media was maintained for 36 days.
3. With this culture a severe anemia was produced in rats weighing 30 gm., with the occasional appearance of Bartonella muris bodies on the red cells. The anemia occurred within 24 hours, and lasted for 3 to 5 days with recovery of the rat. Bartonella muris was recovered in pure culture from the blood of these animals. The blood of these rats was infectious for other 30 gm. rats.
4. 3 week old rabbits were infected with cultures of Bartonella muris, a severe anemia resulting after an incubation period of 48 hours. The organism was recovered from the blood on the 5th day after injection. Bartonella muris is non-pathogenic for adult rabbits.
5. A severe anemia was produced in young guinea pigs with cultures of Bartonella muris within 48 hours. The organism was recovered on the 2nd and 5th days after injection. Postmortem examination revealed changes in the organs similar to those found in splenectomized rats suffering with spontaneous Bartonella muris anemia.
6. The infection was reproduced in white mice. In one instance a severe anemia developed on the 5th and 6th days. The organism was recovered on the 6th day.
7. The anemia was produced in splenectomized adult rats of non-carrier stock. The organism was recovered from the blood stream of these rats. A marked leukocytosis was noted (65,000) at the peak of the anemia as is found in the spontaneous disease in infected splenectomized adult rats.
8. Serological tests have thus far failed to demonstrate the production of agglutinins, though complement-fixing antibodies are present in homologous sera in low dilutions.