s-mobile, Nordwestblock

N. R. V. Southern: "Sub-Grammatical Survival, Indo-European s-mobile
and its Regeneration in Germanic" notes that beside 'proper Germanic'
alternations sp-/f-, st-/T-, sk-/h- there are also sp-/p-, st-/t-, sk-
/k- and concludes that that the process that involved s-mobile must
have been active after the Grimm-shift in Germanic. But since I
recognised several of Kuhn's proposed Nordwestblock roots in his
alleged after-Grimm alternations (and what's a root with initial
/p-/ doing in Germanic anyway?) I think it's safe to conclude that s-
mobile existed in Nordwestblockese. Given the geographical position
of Nordwestblock, one would expect it to loan from Vennemann's
AfroAsiatic 'Atlantic', if indeed s-mobile was once a causative "s-
preformative".

Torsten