Abstract
Microcanonical ensembles in which the possible macroscopical states have different probabilities of occurrence are described. The number of complexions associated with each macroscopical state is modified to be the product of the Boltzmann's number of complexions by the probability of this state occurring. It is shown that in the case of quadratic forms of the energy the equilibrium macroscopical state does not correspond to an equipartition of energy. The model is discussed in a general context and is then applied to an ecological example. Self-organization processes are described which result from the unequal distribution of the energy in the different states