[en] New observational data are given for the spectra of several Wolf-Rayet stars. Evidence is produced for the presence of C IV in the WN sequence and for a central reversal of the H, He I, and He II lines. The spectra of two Of stars are described, and some properties of the Of shells are discussed, especially the ionization conditions and the excitation process. The absence of well-marked dilution effects and other considerations suggest that the size of a Wolf-Rayet shell is not much larger than that of the photospheric surface, so that an occultation effect should be expected in certain cases. The relative abundances of carbon and nitrogen in the ejected shells of Wolf-Rayet, Of, and P Cygni stars, as well as of novae, are discussed, since W objects have been observed which are intermediate between the pure nitrogen and carbon sequences. Suggestions are made concerning the classification, absolute magnitudes, temperatures, and radii of Wolf-Rayet stars and planetary nuclei, as well as concerning the application of Zanstra's theory to the nebulae with a Wolf-Rayet nucleus or to the Wolf-Rayet stars themselves.
