This book is dedicated to Prof. Dr. K. Mägdefrau (Münster, Germany) at the occasion of his 70th birthday. Several of his colleagues and former students have contributed on the theme ‘Adaptation of cryptogamic organisms to their environment’. Modern opinions about the fungi in this respect are given in the chapters: Chemotaxonomy of the fungi (18 pp, by A. Bresinsky), Problems concerning the system of the Ascomycetes (15 pp, by E. Müller), and The new system of the Basidiomycetes (45 pp, by F. Oberwinkler).