The Fifth Ir Gene Workshop was held at the Chase-Park Plaza Hotel, St. Louis, MO, August 28-31, 1982; 240 scientists participated in the Workshop. The man- uscripts compiled in this book describe the state of the art concerning Ir genes. Although the notion of Ir Genes: Past, Present, and Future has not been ad- dressed specifically by each author, the reader is certain to get this flavor from the contributions. In this Preface, we have tried to summarize...