Two years ago, about twenty people gathered informally in our institute to discuss mitosis. We took this opportunity to try to separate the "hard" facts of mitosis which are accepted by most people, from the "soft" ones which are still open for discussion. Surprisingly few "hard" facts survived with their reputation still intact. This result led us to orga nize a similar meeting on a larger scale. The outcome was the workshop "Mitosis: Facts and Questions," which was held at the German Cancer Research Center in Heidelberg from April 25-29, 1977. An introductory lecture was given for each of...