Symmetric vs. asymmetric planetary nebulae: morphology and chemical
  abundances
  We analyse a large sample of galactic planetary nebulae based on their
chemical composition and morphology. A recent morphological classification
system is adopted, and several elements are considered, namely He, N, O, S, Ar,
Ne, and C in order to investigate the correlations involving these elements and
the different PN types. Special emphasis is given to the differences between
symmetric (round or elliptical) nebulae and those that present some degree of
asymmetry (bipolars or bipolar core objects). The results are compared with
previous findings both for PN in the Galaxy and in the Magellanic Clouds.
