The Factors Concerned in the Appearance of Nucleated Red Blood Corpuscles in the Peripheral Blood

1. Hemorrhage with immediate saline infusion causes the appearance in the peripheral blood of a slightly increased number of normoblasts provided normoblasts are already present in the blood stream. Marrow hyperplasia does not intensify this reaction and the cells found probably do not leave the marrow pulp but are in the blood stream at the time of the experiment. 2. The slight increase in cells occurring immediately after hemorrhage and infusion is designated a pseudocrisis. True crises are much more extensive; they tend to occur just before rapid increase in the erythrocyte count and usually towards the end of the 1st week following hemorrhage. 3. Red cells and white cells tend to move from the marrow together, but this association is not invariable. 4. After repeated hemorrhages regeneration occurs independently of the appearance of nucleated red cells in the peripheral blood. 5. Repeated hemorrhages associated with extension of erythrocyteproducing marrow lead to polycythemia but not to a conspicuous increase in speed of regeneration.