New observations of HM Sge and V1916 Cyg: simultaneous presence of increasing excitation and cool features.

Sumniary. We report on systematic observations at Asiago of HM Sge and V 1016 Cyg, two peculiar variables interpreted as proto-planetary nebulae with symbiotic nature, which is now supported by infrared data. HM Sge has shown during 1978 new variations of its excitation stage, revealing for the first time a strong He 114686 line. In V 1016 Cyg the steady trend toward higher excitation has led to stronger [Fe vn] and to the emergence of characteristic features at 6830 and 7090. At the same time we remark that Fen lines reappear. Thus this phase resembles the one being observed by Thackeray in RR Tel since the later 1960's up to now. Key words: variable stars - stellar spectra - stellar evolution - infrared and radio sources