The first three chapters of Vol. 3 of Bio-organic Marine Chemistry deal with the chemistry and function of peptides. Chapter 1 by Ireland and coworkers serves as an introduction to marine-derived peptides. It is arranged phyletically and encompasses the entire range from dipeptides to a compound with 95 amino acid residues. Peptides involved in primary metabolism and hence belonging to the realm of macromolecular biochemistry are excluded. However, it might be mentioned in passing that the dividing line between large and small molecule chemistry is continually becoming less distinct. Not only...