The present paper reports the essential results of the experimental inoculation with plague of 2278 wild rats (Mus norvegicus). It was expected and hoped that the series might be run to ten thousand but it became necessary to terminate the experiment on account of the disappearance of plague in the community in which it was carried on. The small number of cases of late bacteremia and resolving plague render the results inconclusive. They are published, however, for the information of other workers in this field. It is believed that this work constitutes the first demonstration of the existence of a B. pestis bacteremia in some cases of resolving plague.
The original plan was to determine at various intervals after inoculation what proportion of rats would show lesions of resolving plague and for how long plague bacilli would survive in their tissues.