  Studies of the Fundamental Plane of early-type galaxies, from small to
intermediate redshifts, are often carried out under the guiding principle that
the Fundamental Plane reflects the existence of an underlying mass-luminosity
relation for such galaxies, in a scenario where elliptical galaxies are
homologous systems in dynamical equilibrium. Here I will re-examine the issue
of whether empirical evidence supports the view that significant systematic
deviations from strict homology occur in the structure and dynamics of bright
elliptical galaxies. In addition, I will discuss possible mechanisms of
dynamical evolution for these systems, in the light of some classical
thermodynamical arguments and of recent N-body simulations for stellar systems
under the influence of weak collisionality.
