In view of the brief season during which Rocky Mountain spotted fever prevails, uninterrupted study of the disease is conditioned on the maintenance of the infection in experiment animals.
In a previous communication1 my inability to preserve the disease by inoculation from guinea-pig to guinea-pig was referred to, and the hope was expressed that alternation of the infection between the monkey and the guinea-pig might result in the preservation of the virus.
This experiment has been entirely successful and Table 1 illustrates the life history of the virus since it was obtained from the patient, Bradley.
All infected animals have run identical courses of fever, which are typical in this respect, that an incubation period of from two to four days intervenes between the time of inoculation and the onset of the regular febrile course. Commonly a moderate rise in temperature follows immediately on the inoculation and persists for