Blood‐cell Cycles in Polycythæmia Vera

SUMMARY Two patients with polycythæmia vera were studied in order to determine whether blood‐cell cycles were present. Neutrophil and platelet cycles were found in one and a reticulocyte cycle in the other. The findings suggest that control of cell production by the marrow is partly retained in polycythæmia vera. In contrast to the findings in chronic granulocytic leukæmia, no evidence was found for slowed cellular maturation.