FLAGELLUM, an organ attached to various small animals for the purpose of locomotion. It consists of a long slender fila ment, anterior in progression, which causes the body to be drawn along by an undu lating movement. These vibratile proc esses come from a distinct basal granula, may be either one or few in number and can move independently of each other. In cases where the body is fixed, the flagellum causes a current towards it by which the animal obtains its food. It also acts as a propeller like the tail of a fish by posterior movement. See CYTOLOGY and PROTOZOA.