  We show that the observed ratio of the subtypes Ib,c and II core-collapse
supernovae depends on the metallicity of the host galaxy, as expected on
theoretical grounds. However, the observed relation differs considerably from
expectations based on non-rotating models of single stars with mass loss. We
argue that the predictions of recent models with rotation offer a much better
agreement with observations, at least for progenitor stars with solar
metallicity; calculations of models with higher and lower metallicities are
required in order to substantiate these conclusions. We also suggest that
systematic surveys of core collapse supernovae up to redshift of 1 with the
SNAP satellite would allow to probe the effect of metallicity on supernovae
properties during the past history of the universe.
