  We present results from an extensive set of simulations of gravitational
fragmentation in the presence of magnetic fields and ambipolar diffusion. The
average fragmentation spacing in the nonlinear phase of evolution is in
excellent agreement with the prediction of linear perturbation theory. The time
scale for nonlinear growth and runaway of the first core is $\approx 10$ times
the calculated growth time $\taugm$ of the eigenmode with minimum growth time,
when starting from a uniform background state with small-amplitude white-noise
perturbations. Subcritical and transcritical models typically evolve on a
significantly longer time scale than the supercritical models. Infall motions
in the nonlinear fully-developed contracting cores are subsonic on the core
scale in subcritical and transcritical clouds, but are somewhat supersonic in
supercritical clouds. Core mass distributions are sharply peaked with a steep
decline to large masses, consistent with the existence of a preferred mass
scale for each unique set of dimensionless free parameters. However, a sum
total of results for various initial mass-to-flux ratios yields a broad
distribution reminiscent of observed core mass distributions. Based on our
results, we conclude that fragmentation spacings, magnitude of infall motions,
core shapes, and, especially, the curvature of magnetic field morphology, may
serve as indirect observational means of determining a cloud's ambient
mass-to-flux ratio.
