We study the motions of Lagrangian radii in an N-body Plummer model. Comparisons between models with self-consistent and fixed potentials, and with different numbers of stars, help to clarify these motions. The predominant movements appear to be a manifestation of 1/sq rt N noise. During the investigations, the centers of the cores of the systems must be found. The movements of these centers are presented in the latter part of the paper.