Partial conservation of axial-vector current effects in the MIT bag model

We extend the calculations of the MIT-bag-model spectrum to include the pion-field exchange energy in a manner consistent with the ideas of partial conservation of axial-vector current. We find that this interaction energy is sufficient to destabilize the quark bag whose quantum numbers are those of the pion. The $\eta$ mass is also improved, while other features of the low-lying hadron mass spectrum are not significantly modified.