It is indeed nice to talk about phonetic changes in general.
I have one question concerning your presentation on Polish phonetic
pecularities connected with fricatives and stops.
You say, undoubtedly on good grounds, that in words such as:
-tka€  Ä'§- and -drgn€  Ä'¥Ä'§- the clusters [tk] and [drgn]
respectively were once split by the so-called 'yers'.
I was wondering why Polish, on its way of development, lost these
'yers' and made these consonantal clusters quite difficult to
I hope I did understand this problems this way.
Anyway, sorry for my perhaps simplistic question.

Yours sincerely,
€  Å'¡ukasz Mokrzycki