  We find that the statistics of levels undergoing metal-insulator transition
in systems with multi-parametric Gaussian disorders and non-interacting
electrons behaves in a way similar to that of the single parametric Brownian
ensembles \cite{dy}. The latter appear during a Poisson $\to$ Wigner-Dyson
transition, driven by a random perturbation. The analogy provides the
analytical evidence for the single parameter scaling of the level-correlations
in disordered systems as well as a tool to obtain them at the critical point
for a wide range of disorders.
