For the purpose to clarify the mechanism of phagocytosis or pinocytosis, the observations on the tumor ascites, including the macrophages as well as the tumor cells, were carried out by incubating with the iron colloid with or without pretreatment by several inhibibitors of glycolysis, oxidative phosphorylation and respiration, or under hypotonic or cold environments. The results have demonstrated that there are three steps in the phagocytosis. The first step is the adhesion of the substance to the cell surface, which is not an
energy-requiring process. The second step is the engulfing which proceeds by using the energy supplied by glycolysis. The third is the accumulation of the substance into the vesicles through the canaliculi connecting the cell surface with the vesicles.
The discussion was made on the existence of the active site on the cell surface to which the substance can be adhered, and the accumulation mechanism of the material into the phagocytic vesicles by the membrane flow, the flowing movement of the outer lipid layer of a unit membrane through the canaliculi which connect the cell surface to the phagocytic vesicles.</p
