  We first discuss the theoretical and phenomenological significance of the
sigma meson ($\sigma$) in QCD. It is indicated that if the collective modes
with the mass 500-600 MeV exists in the $I=J=0$ channel, various empirical
facts in hadron physics can be naturally accounted for, which otherwise would
remain mysterious. We propose several experiments to produce and detect the
$\sigma$ in nuclei using nuclear and electro-magnetic projectiles. The recent
CHAOS data which show a spectral enhancement near the 2 $m_{\pi}$ threshold in
the $\sigma$ channel from the reactions A$(\pi, 2\pi)$A' where A and A' denotes
nuclei is interpreted as a possible evidence of a partial restoration of chiral
symmetry in nuclei.
