1.A pathogenic microörganism was obtained in pure culture from animals infected with the virus of tsutsugamushi disease.
2.In morphology and staining reactions, this microörganism resembles closely the Rickettsia.
3.On inoculation of these cultures into guinea pigs, hemorrhagic lesions developed which were indistinguishable from the hemorrhages following the injection of the virus of tsutsugamushi disease. The cultures were pathogenic, to some extent for rhesus monkeys, the injected animals showing some evidence of active immunity against the virus.
4.There has, as yet, been no opportunity to control these observations by the study of tsutsugamushi disease in man or by the examination of infective mites.