Emission lines in the spectra of WC9 stars have been studied. It is shown that there are clear differences between the spectra of BD + 30 3639 and the central star of He2-99. It is argued that there are no systematic spectral differences between the WC9 CSPN and the Pop.I WC9 stars: both kinds of WC9 stars show a substantial and overlapping range of emission line strengths and widths. It is suggested that the current concept (that the spectra of WC9 CSPN are systematically different from the spectra of Pop.I WC9 stars because they are an order of magnitude less massive) be replaced by a more plausible concept that attributes the spectral differences to the different importance of radiation pressure in the formation of the stellar spectrum.