  A large deep and nearly complete B<24.5 redshift sample is used to measure
the change in distribution function of the stellar mass production rate in
individual galaxies with redshift. The evolution of the star formation rate
distribution with redshift is interpreted in terms of the history of spiral
galaxy formation, with the disk component modelled as a single evolving entity,
and the characteristic timescales, luminosities, and epochs varying according
to galaxy type. The more massive forming galaxies seen at z=1 to 3 are
identified as earlier type spirals, whose star formation rates are initially
high and then decline rapidly at z<1, while for later type spirals and smaller
mass irregulars the mass formation rates at z<1 are lower, and the formation
process persists to redshifts much closer to the present epoch. We find that
these models can be consistent with the data and fit well into a broad picture
of other recent results if qnought=0.02 and many of the disks begin their
growth at z<<3, but that they predict too many bright star formers at high z in
flat universes.
