  Model-independent effects of $\Delta$(1232) excitation on nucleon
polarizabilities are computed in a Lorentz-invariant fashion. We find a large
effect of relative order $(M_\Delta - M)/M$ in some of the spin
polarizabilities, with the backward spin polarizability receiving the largest
contribution. Similar subleading effects are found to be important in the
fourth-order spin-independent polarizabilities $\alpha_{E\nu}$, $\al_{E2}$,
$\be_{M\nu}$, and $\be_{M 2}$. Combining our results with those for the
model-independent effects of pion loops we obtain predictions for spin and
fourth-order polarizabilities which compare favorably with the results of a
recent dispersion-relation analysis of data.
