  We develop an idealized inside-out formation model for disk galaxies to
include a realistic mix of galaxy types and luminosities that provides a fair
match to the traditional observables. The predictions of our infall models are
compared against identical models with no-size evolution by generating fully
realistic simulations of the HDF, from which we recover the angular size
distributions. We find that our infall models produce nearly identical angular
size distributions to those of our no-size evolution models in the case of a
Omega = 0 geometry but produce slightly smaller sizes in the case of a Omega =
1 geometry, a difference we associate with the fact that there is a different
amount of cosmic time in our two models for evolving to relatively low
redshifts (z \approx 1-2). Our infall models also predict a slightly smaller
(11% - 29%) number of large (disk scale lengths > 4 h_{50} ^{-1} kpc) galaxies
at z \approx 0.7 for the CFRS as well as different increases in the central
surface brightness of the disks for early-type spirals, the infall model
predicting an increase by 1.2 magnitudes out to z \approx 2 (Omega = 0), 1
(Omega = 1), while our no-size evolution models predict an increase of only 0.5
magnitude. This result suggests that infall models could be important for
explaining the 1.2-1.6 magnitude increase in surface brightness reported by
Schade et al. (1995, 1996a, 1996b).
