Long ū in Germanic

Proto-Germanic long ī derives from either PIE i + H or from PIE ei . In an earlier paper (Perridon 2001) I argued that Proto-Germanic ū has a similar derivational history, the only difference being that the change from full grade eu to ū did not affect the whole of the lexicon, whereas the change from ei to ī was exceptionless. In this paper I will discuss some recent contributions on the origin of ū that either explicitly or implicitly reject the idea of an ‘imperfect’ sound law.