  We discuss contributions of chiral bosons to baryon spectra in the MIT bag
model. It is believed that within hadrons, chiral bosons are degrees of freedom
which are independent of gluons to provide strong interactions between quarks.
In the original MIT bag model, only interaction mediated by gluon exchanges was
considered, by contrast, in this work we take into account the interaction
mediated by the exchanges of chiral bosons $\sigma$ and $\pi^{(\pm,0)}$. Then
following the standard approach, we minimize the effective hamiltonian which
includes both the contributions from gluon and chiral-boson exchanges with
respect to the bag radius to obtain the effective radius. By re-fitting the
spectra of baryons, we find that the contributions from the boson-exchange may
be 40% of that from gluon-exchanges and meanwhile the bag constant $B$, the
zero-point energy $z_0$ almost do not change. It indicates that in the original
version of the MIT bag model, the intermediate-distance interaction due to the
chiral-boson exchanges is attributed into the effective coupling $\alpha_c$
which stood for the short-distance interaction caused by the gluon exchanges
and the long-distance effects reflected by $B$ and $z_0$ are not influenced.
