In a previous paper (Véron et al. 1997) we presented medium resolution (3.4 Å FWHM) spectroscopic observations of 15 ``transition objects'', selected for having an ambiguous location in the Veilleux & Osterbrock (1987) diagnostic diagrams, and showed that most of them were in fact ``composite'', this being due to the simultaneous presence on the slit of both a Seyfert or Liner nucleus and a Hii region. Here, we report new spectroscopic observations of 53 emission-line galaxies with a ``transition'' spectrum, bringing up to 61 the total number of observed objects in an unbiased sample of 88 ``transition objects''. Almost all of the observed galaxies have a ``composite" nature, confirming the finding that true ``transition'' spectra may not exist at all.
By eliminating ``composite objects'' from the diagnostic diagrams, a clear
separation between the different classes of nuclear emission-line regions
(Seyfert 2s, Liners and Hii regions) becomes apparent; by restricting the
volume occupied by the different line-emitting regions in the 3-dimensional
diagnostic diagrams, we are also restricting the range of possible physical
parameters in these regions. There seems to be no continuity between
Seyfert 2s and Liners, the two classes occupying distinct volumes in
the 3-dimensional space defined by 5007/H, 6583/H, and 6300/H.
Key Words : galaxies: active - galaxies: nuclei