From: Piotr Gasiorowski
Message: 49164
Date: 2007-06-26
> I don't know, but all theories will have to live with that problem.This could be compared with other Balto-Slavic (secondary?) full grades
> One possibility is accent shift half-way through the process of
> producing zero-grade: *werH1-tó- > *worH1-tó- > *wrH1tó- > *wr.thó-
> ; at the stage *worH1-, the o-vowel spread to the collective which
> was stressed on the initial.