Biomembranes are not only principal constituents of the cell but also a major site of biological activity. Studies on biomembranes are therefore, crucial for furthering our understanding of life processes. A special research project on biomembranes involving more than 100 in­ vestigators was conducted under a grant from the Ministry of Education, Science and Culture of Japan between 1978 and 1981. This has resulted in marked progress on basic biomedical studies on biomembranes in Japan. This book is a compilation of several major developments made during this project in the field of "Structure, Dynamics, and Biogenesis of Biomembranes. " Developments in other fields constitute the contents of a companion volume, "Transport and Bioenergetics in Biomembranes," edited by Sato and Kagawa. In these two volumes the authors review recent advances which have been primarily made in their own labora­ tories and include relevant work carried out by other investigators. Eight topics are presented in this volume. Ikegami and coworkers review molecular dynamics in lipid bilayers, reconstituted membranes and biological membranes as studied by nanosecond fluorescence spec­ troscopy with an emphasis on the wobbling in the cone model. The fol­ lowing two chapters deal with virus-induced membrane fusions. Ohnishi and Maeda describe an assay method for envelope fusion using spin­ labeled phospholipids and report several characteristic results obtained by this method including low pH-induced fusion of influenza virus.