Four years ago The Blue Light Syndrome was published as the Proceed­ ings of the 1 st International Conference on the Effect of Blue Light in Plants and Microorganisms. Subsequently the interest in this fascinating and growing field of research has further increased, as is reflected by numerous publications. Blue light effects cover such a wide spectrum of organisms, responses and methods that communication among scientists with backgrounds in biology, biochemistry, and biophysics is particularly necessary. These facts not only justified, but demanded calling the "Blue Light Family" together again. In spite of many fmancial problems, the second confer­ ence attracted 113 active members from 19 countries. The 2nd International Conference on The Effect of Blue Light in Plants and Microorganisms was held in July 1984, like the first at the University of Marburg. The organizer could again rely on the help of the International Advisory Committee (W. Briggs, Stanford; M. Furuya, Tokyo; J. Gressel, Rehovot; S. Miyachi, Tokyo; W. Rau, Miinchen; J. Schiff, Waltham; P .-S. Song, Lubbock). The very generous financial as­ sistance from the DFG and the support of the Philipps-Universitat Mar­ burg and its Sonderforschungsbereich "Zellenergetik and Zelldifferen­ zierung" were the prerequisites to organizing the conference. The present book consists of 56 original papers. The partitioning into eight chapters is always a problem. The grouping of different aspects of the papers into these chapters has not always been obvious, so that one or the other contribution could possibly fit in another chapter.