The presented text is a partial study of the problem of parenthesis occurring in contemporary Polish; the phenomenon which has not been fully described, yet. The author's attention has focused on the phrase 'jak widac' (as it seems), considered by many researchers as having a parenthetical structure. Conducted observations confirmed the necessity to differentiate two units in the form of 'widac', and they proved that, within embedded usages, there is an impersonal predicative which obligatorily demands the 'jak' component. It has also been pointed out that there are formal restrictions on the way of realization of the parenthetic structure constituted by 'widac'. The analysis has used research methods suggested by Z. Saloni and M. Swidzinski in 'Skladnia wspolczesnego jezyka polskiego' (Contemporary Polish Syntax) (1998), developed by numerous researchers, including M. Szupryczynska in 'Pozycja skladniowa frazy celownikowej w zdaniu polskim' (The Syntactic Position of the Dative Case Expression in a Polish Sentence) (1996).