1. Purified tuberculo-polysaccharides are relatively innocuous both to normal and to tuberculous guinea pigs.
2. Both tuberculo-polysaccharides and polysaccharides from pneumococci call larger numbers of leucocytes from the blood vessels than do saline and dextrose and trehalose.
3. The mechanisms controlling the delivery of lymphocytes and neutrophils into the blood stream are different.
4. Slight irritation of the peritoneal lining slows the delivery of lymphocytes to the blood stream.
5. There are two phases in the reaction of the bone marrow to intraperitoneal injections. Correlated with the draining of neutrophils from vessels to tissues, owing to the presence of foreign materials in the latter, there is a draining of young neutrophils from the marrow into the sinuses of the marrow as these same materials reach the sinuses. The subsequent disintegration of the neutrophils extravasated into the tissues is correlated with increased myeloid activity in the marrow.