Physical and Chemical Properties of Planetary Nebulae with WR-type
  Nuclei
  We have carried out optical spectroscopic measurements of emission lines for
a sample of Galactic planetary nebulae with Wolf-Rayet (WR) stars and weak
emission-line stars (wels). The plasma diagnostics and elemental abundance
analysis have been done using both collisionally excited lines (CELs) and
optical recombination lines (ORLs). It is found that the abundance discrepancy
factors (ADF=ORL/CEL) are closely correlated with the dichotomy between
temperatures derived from forbidden lines and those from He I recombination
lines, implying the existence of H-deficient materials embedded in the nebula.
The H$\beta$ surface brightness correlations suggest that they might be also
related to the nebular evolution.
