The six papers comprising volume 3 of Advances in Bryology treat various aspects of bryophyte ultrastructure. Together with the paper, “Desiccation and Ultrastructure in Bryophytes,” by M. J. Oliver and J. D. Bewley in volume 2 of the Advances (1984), they provide a comprehensive summary of current investigations into the ultrastructure of mosses, liverworts, and homworts. Developmental, functional, and descriptive aspects of the featured structures and organelles receive emphasis in these papers, which contain a wealth of comparative data that is useful in assessments of the phylogenetic relationships of bryophytes.