The title of this book, which was also the name of the symposium, provided an opportunity to combine papers on many varied subjects. Some of the 19 authors presented a mere compilation of the literature of the subject concerned but most of them also included the results obtained from their own work in these papers. Since the stream of phycological literature is considerable, as can be seen from Silva’s annual phycological bibliography in Phycologia, compilations are also welcome. Papers on taxonomy of Algae were given by Prescott, Van den Hoek and Christensen. The last mentioned author presented a project for a modern classification based on the presence or absence of chlorophyll b and the flagellar structure. This classification appears to have been accepted by several phycologists now. Arguments for including unialgal cultures in most monographical studies on Algae were brought to the fore by Van den Hoek. He demonstrated some of the results from his monographical study of Cladophora in search of reliable characters to recognize the species of this genus. Prescott’s long paper is disappointing because several inaccuracies have slipped in.