I. Characterization of the Multipotential Stem Cell (CFU-s) -- 1. The Appearance of the Multipotential Hemopoietic Stem Cell -- 2. An Immunologic Approach to Cell Cycle Analysis of the Stem Cell -- 3. Physical Separation of the Cycling and Noncycling Compartments of Murine Hemopoietic Stem Cells -- 4. Characterization of Bone Marrow and Lymph Node Repopulating Cells by Transplanting Mononuclear Cells into Radiated Dogs -- II. Humoral and Cellular Control Agents -- 5. Concepts and Observations on the Regulation of Granulocyte Production -- 6. The Regulatory Role of the Macrophage in Normal and Neoplastic Hemopoiesis -- 7. Humoral Regulation of Eosinophil Granulocytopoiesis -- 8. Studies of the Erythroid Inductive Microenvironment in Vitro -- 9. In Vivo Colony Forming Unit Population Sizes in Hypertransfused Sl/Sld Mice -- III. Physiology of Committed Stem Cells (CFU-e and CFU-m) -- 10. Recognition of Hemopoietic Progenitors -- 11. Relationships between Early Hemopoietic Progenitor Cells Determined by Correlation Analysis of Their Numbers in Individual Spleen Colonies -- 12. Some Characteristics of in Vitro Erythroid Colony and Burst-Forming Units -- 13. Colony-Forming Unit, Megakaryocyte (CFU-m): Its Use in Elucidating the Kinetics and Humoral Control of the Megakaryocytic Committed Progenitor Cell Compartment -- IV. Physiology of Committed Stem Cells (CFU-c) -- 14. Negative and Positive Feedback Control of the Committed Granulocytic Stem Cell Compartment -- 15. Colony-Stimulating Factor and the Differentiation of Granulocytes and Macrophages -- 16. Characteristics of the in Vitro Monocyte-Macrophage Colony-Forming Cells Detected within Mouse Thymus and Lymph Nodes -- 17. Physical Characterization of a Subpopulation of Granulocyte/Monocyte Progenitor Cells (CFU-c) -- 18. Cell-Factor Interaction in Populations of Normal and Leukemic Blood Cells -- V. Bone Marrow Transplantation Immunology -- 19. Bone Marrow Transplantation Immunology -- 20. Modulation of Graft-versus-Host (GvH) Disease in the Rat; Effect of Hydroxyurea on the Mixed Lymphocyte Reaction and Graft-versus-Host Reactivity -- 21. Mechanism of Donor to Host Tolerance in Rat Bone Marrow Chimeras -- 22. Effects of a Cell-Free Helper Factor(s) on the Kinetics of T-Cell Responses to Histocompatibility Antigens -- VI. Experimental Models of Clinical Conditions in Hematology -- 23. The E(AkR)-Leukemia as Murine Model of Human Acute Lymphoid Leukemia for Immunotherapy Trials -- 24. Experimental Chemotherapy: A Rat Model for Human Acute Myeloid Leukemia -- 25. Serum Colony Stimulating Factor: A Marker for Graft-versus-Host Disease in Humans -- 26. Changes in Human Bone Marrow Colony-Forming Cells following Chemotherapy Using an Agar Diffusion-Chamber Technique -- 27. Graft-versus-Leukemia, Donor Selection for Adoptive Immunotherapy in Mice