Abstract: The present invention provides an automatic streaking device for bacterial specimens, which device produces a repetitive, overlapped plurality of figure eight patterns. An electrically conductive loop is displaced in a direction perpendicular to the major axis of the figure eight pattern. Means are provided for non-linearly advancing the loop in a direction perpendicular to the major axis of the figure eight pattern so as to vary the resulting pattern in a predetermined manner. Means are also provided for automatically sterilizing the loop when the series of figure eight movements are terminated. A first motor drives a pair of crank arms having different lengths in order to determine the amplitudes of the figure eight patterns in two mutually perpendicular directions. A second, variable speed, reversible motor is coupled to and drives a carriage that supports the first motor and the crank arms so as to vary the center-to-center spacing between adjacent figure eight patterns.