Explants of rabbit spleen were placed in plasma clots, inoculated with a 24-hour culture of L. monocytogenes and sealed in depression culture slides according to the method of Maximow. Approximately 0.01 ml of the bacterial suspension was placed in each culture while control cultures were prepared without bacteria. Observations of living tissue cultures revealed that tissue growth was not inhibited by the presence of L. monocytogenes. In all inoculated tissue cultures the bacteria were always motile when observed under the microscope. Infected tissue cultures incubated 48 hours or longer required refrigeration for at least 7 days in order to demonstrate the presence of L. monocytogenes in bacteriological media. Study of stained sections of the inoculated explants disclosed what appeared to be a proliferation of the vascular endothelium and connective tissue. The pathological change was granulomatoid in nature with the production of granuloma-like tissue. This lesion seemed to be similar to that seen in granulomatosis infantiseptica, a disease of new-born infants described in Germany, caused by L. monocytogenes.