The papers published in this Volume are the fruits of a symposium held in Regensburg in April 1987. The meeting was held to com­ memorate two most significant events in the development of com­ pound eye research. In chronological order these are firstly, Sigmund Exner's seminal monograph on the physiology of compound eyes of crustaceans and insects, which was first published in Vienna in 1891, and is now shortly to appear for the first time in the English translation [Exner, S. (1989) The Physiology of the Compound Eyes of Insects and Crustaceans. Springer Berlin Heidelberg New York Tokyo]. Secondly, the meeting was also held in honour of Professor Hansjochem Autrum's 80th birthday. Professor Autrum, who is justly acknowledged as one of the pioneers of modern compound eye research, attended the meeting as the guest of honour. In keeping with these historical occasions, it has been our intention in this volume to present a comprehensive collection of short reviews covering the major aspects of compound eye research. Whilst the most up-to-date developments have been included in every field from optics, through photochemistry, phototransduction, integrative processes and behavior, an attempt has also been made to provide a historical perspective.