very important, especially the comparison of vertebrate and invertebrate transduction mechanisms. The workshop was very successful and the outcome of the discussions proved it worth the effort. To no small extent has that success been made possible by Dr. Silke Bernhard who with a combination of authority and charm together with her extremely efficient and dedicated staff organized this workshop, providing the conditions and framework for a scientific debate of outstanding quality in a friendly and pleasant atmosphere. The great majority of participants were also very committed to making this workshop successful. Besides the reports of the four discussion groups, this publication contains the background papers which were revised by the authors partly as a result of suggestions of some participants. I hope this book will give a fair overview of the state of our knowledge of research in visual transduction. It was a pleasure to edit, especially because of the friendly and very efficient commitment of K. Geue, J. Lupp, and A. Eckert and the cooperativeness of most of the contributors. Particularly I would like to acknowledge gratefully the extensive efforts and patience of the four rapporteurs, M.L. Applebury, W.H. Miller, W.G. Owen, and E.N. Pugh, Jr., in compiling, writing, and revising the group reports. REFERENCES (1) Altman, J. 1985. Sensory transduction, new visions in photoreception. Nature 313: 264-265. (2) Hagins, W.A. 1972. The visual process: Excitatory mechanisms in the primary receptor cells. Ann. Rev. Biophys. Bioeng. 1: 131-158.