"IAU Transactions" are published as a volume corresponding to each General Assembly. Volume A is produced prior to the Assembly and contains reports on astronomy, prepared by each Commission President. The intention of the publications is to summarize the astronomical results that have affected the work of the Commission since the production of the previous reports up to a time which is about one year prior to the General Assembly. Volume B is produced after the Assembly and contains accounts of Commission Meetings which were held, together with other material. The reports included in the present volume range from outline summaries to lengthy compilations and references.

In step with the rapid growth of research into the biochemical and functional characterization of the endosome, Volume 19 surveys the recent advances in the methodological aspects of this field. Coverage includes the use of free flow electrophoresis to define endosome subpopulations, the endosomal compartments in rat hepatocytes, the role of endosomes in transmembrane signalling, and six additional articles.