One-dirme nsional calculations of the evolution of protogalaxies are presented. The stellar component, three phases of the interstellar medium and their interactions are treated in detail, taking into account stellar evolution, stellar mass loss, nucleosynthesis, heating and cooling of the gas, and condensation and evaporation of clouds. In agreement with observations the models yield massdependent results of 1) supernova-driven galactic mass loss that will form a hot corona around ellipticals and accounts for an abrupt termination of the evolution of dE's, 2) metal-enrichment, explaining the L-Z-relation, 3) low metallicity gradients in dwarf galaxies.