Abstract
Acute leukopenia produced by the injection of foreign protein substances was noted in 1886 by Wyssokowitsch, and was attributed at first to destruction of white cells (Lowit -1892) and later to withdrawal of leukocytes from the peripheral circulation into vessels of the viscera. In substance these are the two theories that prevail today. | There is much conflicting evidence on the mechanism of leukopenia. Some of it is favorable to either or the two theories mentioned, some to neither or to both. The leukopenia occurring with damage to bone marrow by a chemical or toxic agent (agranulocytosis) will not be considered here.