  The galactic evolutionary theory is now sufficiently mature to provide
information about the galaxy formation phase. From evolutionary models we
establish a link between the present features of late type galaxies and the
protogalactic density fluctuations. This link is used to estimate the
fluctuation power spectrum amplitude at galactic scales. The agreement with the
power spectrum derived from galaxy distribution and extrapolated to galactic
scales, is satisfactory. Meanwhile, the comparison with respect to the standard
cold dark matter power spectrum normalized to COBE satellite meassurements
reveals only a marginal agreement. Among the most interesting results, the
Tully-Fisher relation and the constant central brightness pointed out by
Freeman (1970) appear to be the natural consequences of the initial
cosmological conditions.
