1. Five human lymphatic and myeloid reticulosarcomas were transmitted to fowls in series.
2. The pathologic changes produced in fowls consisted in proliferation of reticulo-endothelial cells (reticulosarcoma and allied conditions) or those of immature myeloid cells (myelosarcoma, myelosis or myeloid metaplasia). These different forms of leukosis may occur alternately in subsequent generations or simultaneously in the same bird. Neither erythroleukosis nor lymphatic leukosis was encountered. These observations conform with our earlier experience gained in experimental studies of human leukemia.
3. The blood picture of infected fowls was consistently aleukemic either with marked leukopenia or slight leukocytosis. There was usually an increase in mature granulocytes at the expense of lymphocytes. Anemia was usually slight.
4. The causative agent can pass through a Chamberland L2 filter.
5. The infective agent can be demonstrated in the blood of patients, in fluid from the thoratic cavity, in the enlarged lymph nodes as well as in the human tumors.