Gut ist eine Lehrart, wo man vom Bekannten zum Unbekannten fortschreitet; schon ist sie, wenn sie sokratisch ist, d.i. wenn sie dieselben Wahrheiten aus dem Kopf und Herzen des Zuhorers herausfragt. Bei der ersten werden dem Verstand seine Uberzeugungen in Form abgefordert, bei der zweiten sie ihm abgelockt. Professor Friederich Schiller Jena, in a letter written on 23 February 1793 to his friend and supporter Korner, father of the poet Theodor Korner. Established clinicians and scientists as weil as students aga in tried the Wilsede experiment for three days and nights and learned from each...

If tumor viruses did not exist in nature they might have been created by scientists interested in basic mechanisms of develop- ment, differentiation, and tumorigenesis. In contemporary euka- ryotic cell biology tumor viruses playa similar role to that which bacteriophages once had for the molecular biology of prokary- otes. Tumor viruses provide extremely useful probes for the above cellular processes since their life cycle is genetically pro- grammed and can be followed at DNA, RNA, and protein levels. The experimental systems reviewed in this volume utilize a wide variety of viruses. A...