This issue is dedicated to the memory of

Professor Dr med. Dietrich Schmlhl 30 September 1925-l 1 October 1990

Director, Institute for Toxicology and Chemotherapy at the German Cancer Research Centre, Heidelberg, who died suddenly and unexpectedly whilst on vacation in Turkey.

Professor Schmahl was the principal organizer of the meeting, the Proceedings ofwhich are covered in this issue. He also contributed frequently with reviews in this journal.

He will be greatly missed.

0305s7372/90/2&3105+01 $03.00/0 $) 1990 Academic Press Limited