The Chemical Evolution of Galaxies: The Stellar Mass-Metallicity   Relation
  The predictions of the multiple burst accretion model of chemical evolution are compared to the observations of the stellar masses and metallicities of star-forming galaxies. With the addition of one parameter, the model can account for the observations of the star-forming galaxies if the observations of the galaxies are identified with the star bursting behaviour of the model. This consistency with the model holds only if galaxy downsizing is assumed to occur. 
F.D.A. Hartwick
astro-ph.GA