The efficient and continuing ingestion of bacteria was dependent upon (a) opsonic factors present in fresh rabbit serum as well as upon, (b) the availability of an adequate supply of glucose in the medium.

The effects of selected enzymatic inhibitors on the metabolic and functional activities of the leucocytes was investigated. Cyanide which inhibited oxygen consumption had no effect on the ingestion or inactivation of bacteria, Iodoacetate and arsenite which blocked glycolysis produced a marked inhibition in particle ingestion. 2,4-Dinitrophenol which stimulated both oxygen consumption and glycolysis, depressed phagocytosis after a 1 hour latent period. It was concluded that phagocytosis was an energy-requiring process in which glycolysis served as the most important source of energy.

Leucocytes which were ingesting heat-killed bacteria exhibited increases in oxygen consumption, glucose utilization, and lactic acid synthesis. The effect of particle ingestion on glycogen metabolism was characterized by an initial period of glycogenolysis followed by an enhanced rate of glycogen synthesis.

Leucocytes which had previously ingested heat-killed bacteria also demonstrated increased rates of phagocytosis.