Abstract
Summary A cell-free filtrate was prepared by the Gross technique from a thymic tumor induced by a single subcutaneous injection of 100 μg DMBA in a Swiss mouse and diagnosed cytologically as a malignant lymphoma, stem cell type. Out of 7 survivors injected with the filtrate at birth, 6 developed malignant lymphomas, while no such tumor occurred in 10 mice treated similarly at the age of 8 weeks. Cytologically they represented the more differentiated malignant lymphomas, namely the lymphocytic type in 5 cases and in one instance the histiocytic type.