General equations of the thermodynamics of micellar systems and of a single micelle are given. Relations among the size distribution of micelles, their surface tension, and the CMC are established. An expression for the constant of the law of mass action is obtained in terms of surface tension. Polymorphous modifications for micelles are analyzed on the basis of the Gibbs-Curie generalized principle. The size distributions for rod-like and disk-like micelles are derived.