The object of this study is to determine various parameters of cellular proliferation, life span and migration patterns in leukemic, normal and other selected individuals with various hematologic diseases affecting leukocytes. Leukemic patients will also be studied to determine the effect of certain chemotherapeutic agents on their leukemic cells. The information is sought to aid in the planning of therapy in leukemia, and such therapy will be devised in some patients. Cells will be labeled with various radioisotopes in order to study various aspects of cellular proliferation and behavior. Human bone marrow and peripheral blood cells from leukemic patients will also be grown in culture chambers in mice.