Proceedings of the Sixth International Conference held at the University of Pennsylvania in June 1991. Data from over 25 taxa of vertebrates, including humans, are presented. Contributions include the work of a number of researchers from the former Soviet Union. Coverage includes recent breakthroughs in understanding the basic mechanisms underlying olfactory, gustatory, vomeronasal, trigeminal and other oral and nasal sensory systems. Other subjects include seriochemicals and the major histocompatibility complex, chemical repellents, and a lengthy discussion of behavior and chemically mediated social communication among a wide variety of vertebrates. Annotation c. by Book News, Inc., Portland, Or.