Abundance Profiles in Disk Galaxies from Nebulae
  Galactic and extragalactic abundance studies of H II regions, planetary nebulae, and supernova remnants are compiled and their implications briefly reviewed. Galaxy global metallicity appears to be related directly to total mass and morphology, while gradient slopes are uncorrelated with these parameters, although barred spirals tend to have flatter profiles than non-barred spirals. N/O behavior is consistent with primary, then secondary, production of N as metallicity increases, and empirical evidence for a metallicity-sensitive C yield is seen. Metallicity-invariant primary production mechanisms are suggested for S, Ne, Ar, and O. 
R.B.C. Henry (U. of Oklahoma)