  We investigate the dynamical response, in terms of disc size and rotation
velocity, to mass loss by supernovae in the evolution of spiral galaxies. A
thin baryonic disc having the Kuzmin density profile embedded in a spherical
dark matter halo having a density profile proposed by Navarro, Frenk & White is
considered. For a purpose of comparison, we also consider the homogeneous and
$r^{-1}$ profiles for dark matter in a truncated spherical halo. Assuming for
simplicity that the dark matter distribution is not affected by mass loss from
discs and the change of baryonic disc matter distribution is homologous, we
evaluate the effects of dynamical response in the resulting discs. We found
that the dynamical response only for an adiabatic approximation of mass loss
can simultaneously account for the rotation velocity and disc size as observed
particularly in dwarf spiral galaxies, thus reproducing the Tully-Fisher
relation and the size versus magnitude relation over the full range of
magnitude. Furthermore, we found that the mean specific angular momentum in
discs after the mass loss becomes larger than that before the mass loss,
suggesting that the mass loss would occur most likely from the central disc
region where the specific angular momentum is low.
