There is a constant influx of cells, chiefly polymorphonuclear leucocytes, into the gastric lumen when the stomach is at rest (average 250 cells per cmm.). After histamine injections or meals the concentration of cells in the juice falls, reaching a minimum in 30-60 minutes, slowly recovering in 2-3 hours. After histamine the total output of cells is raised during the 1st hour but lowered (below control values) during the 2nd, while after meals the increase may be maintained 2-5 hours, the subsequent fall not passing below the control except in 1 case. The fall in cell concentration is due mainly to increased HC1 secretion. Intragastric leucopedesis bears no constant relationship either to the peptic activity of the juice or (apparently) to the proteolytic ferment content of the blood. No connection between blood leucocytosis and leucopedesis is apparent.