[en] The work is based on a singularity-free model of the universe previously proposed by the authors. According to this model, at the beginning of the present expansion phase the universe was filled with prematter for which P = -rho, and rho is about rho(p), the Planck density, and the prematter went over to ordinary matter in the course of time. Two approaches are considered. In the first it is assumed that there are initial perturbations in the prematter. These grow tremendously in the course of time. In the second it is assumed that the prematter has no perturbations, but that perturbations develop as the prematter is converted to ordinary matter. 12 refs