It will not happen very often that a Botanical Society has at the same time tour members, whose memberships last 60 years. The Royal Dutch Botanical Society has this pleasure this year: W. H. Arisz, C. E. B. Bremekamp, G. van Iterson and Th. J. Stomps became members of our society in 1908/9. They all can look back on two generations of botanists and be proud of their contribution to the fascinating progress of Plant Science during this epoch. The Executive Committee of the Society, therefore, believed it justified to devote on this occasion a special issue of the scientific journal of our Society, to all these scientists who have cooperated with it for so many years.