In 1963, 1965 and 1967 "Symposia on Quantitative Biology of Metabolism" were organized on the pretty island of Helgoland (Biologische Anstalt) by me in col­ laboration with O. KINNE and F. KROGER. Unfortunately this worthy approach towards bringing together interested scholars in a regular way ceased, mainly for financial reasons, although the need for and interest in conferences like these for the exchange of ideas on special topics unchangeably persists. So I had to look for other possibilities and one of them was to try to arrange a similar con­ ference under the auspices of NASA. This institution, however, eventually re-. treated, although during my discussion with its representatives a new special theme gained shape. This is the topic to which this volume is devoted: Bio­ genesis. It is also treated in a new way that probably could be a model for. similar undertakings: a symposium by correspondence. In this new approach to scientific information exchange, manuscripts were collected by the editor and sent to every contributor for his comments. The author could then reply by means of a concluding remark. So, in many instances very valuable ideas concerning the topics of the several papers could be gathered and it is to be hoped that this procedure has conferred upon this volume a certain uniqueness. Of course, I had to observe the agreement with Springer-Verlag not to exceed the extent of the volume allotted to us.