The leukocytes of the organism fulfill their physiological roles through the walls of the capillary blood vessels by extending their pseudopods and making deformation movements. The leukocytes of the organism have the characteristics of deformation, wandering, chemotaxis, phagocytosis and secretion. The leukocytes that exude outside the walls of the capillary blood vessels migrate to the inflammatory zone under the attraction of certain chemical substances and play their physiological roles, phagocytose the bacteria and other foreign bodies, and then digest and kill them. At the same time, leukocytes can also secrete a variety of cytokines, which participate in the body’s inflammatory and immune responses. Therefore, leukocytes play their physiological roles by extending their pseudopods and making deformation movements through the walls of hair vessels to reach the organs they act on.