  We follow the chemical evolution of a galaxy through star formation and its
feedback into the inter-stellar medium, starting from primordial gas and
allowing for gas to inflow into the region being modelled. We attempt to
reproduce observed spectral line-strengths for early-type galaxies to constrain
their star formation histories. The efficiencies and times of star formation
are varied as well as the amount and duration of inflow. We evaluate the
chemical enrichment and the mass of stars made with time. Single stellar
population (SSP) data are then used to predict line-strengths for composite
stellar populations. The results are compared with observed line-strengths in
ten ellipticals, including some features which help to break the problem of
age-metallicity degeneracy in old stellar populations. We find that the
elliptical galaxies modelled require high metallicity SSPs (>3 x solar) at
later times. In addition the strong lines observed cannot be produced by an
initial starburst in primordial gas, even if a large amount of inflow is
allowed for during the first few x 10E+8 years. This is because some
pre-enrichment is required for lines in the bulk of the stars to approach the
observed line-strengths in ellipticals.
