Method for measuring the average motion of a large number of biological objects

We have developed a method for measuring the average motion of a large number of biological objects or other small particles. The moving objects are recorded on a motion-picture film. We measure optically the cross correlations between suitable pairs of motion-picture frames. These measurements yield the average motion and the histogram of the displacement vectors of the moving objects, such as Rhizobia bacteria. The motion data are useful for biological and medical studies.