Abstract
The spectrum of the planetary nebula IC 4997 was observed photographically in Crimea in 1972-1996. The objective prism spectrograms were used for estimation of the flux in eleven bright emission lines of the nebula and in the continuum of the central star. Most spectral characteristics were found to change in time. The ratio R of the [O III] lambda 4363 and H gamma fluxes exhibited the greatest change over 1972-1996; this ratio reached a maximum ( logR = + 0.28) in 1992. In the next years it began to decrease. Increases in the excitation and ionization degrees of the nebula were detected.
