This book launches a new continuing series in developmental biology. Any new publishing venture in science can only be justified if it satisfies a need and fulfills that need in an exemplary way. I believe that there is an acute need for comprehensive treatises on specialized topics in developmental biology-especially because this is a very diverse field that receives con tributions from a wide variety of disciplines. It is difficult to remain abreast of progress in multifaceted topics and to understand how the various aspects of a topic interrelate. The volumes that will comprise this series are designed to facilitate those processes. Each volume of this series will attempt to convey the current status of research and thought on a specific topic in development, place current research within historical perspective, and lay the intellectual groundwork for future research. These volumes are intended to provide an in-depth background on these topics for advanced undergraduates, graduate stu dents, and senior scientists. An investigator considering research in one of these areas will get an overview of the field as well as discover the status of recent research in the area."

This series was established to create comprehensive treatises on specialized topics in developmental biology. Such volumes are especially vital in develop mental biology, since it is a very diverse field that receives contributions from a wide variety of disciplines. This series is a meeting-ground for the various practitioners of this science, facilitating an integration of heterogeneous infor mation on. specific topics. Each volume is intended to provide the conceptual basis for a comprehen sive understanding of its topic as well as an analysis of the key experiments upon which that understanding is based. The specialist in any aspect of devel opmental biology should understand the experimental background of the field and be able to place that body of information in context to ascertain where additional research would be fruitful. At that point, the creative process takes over, and new experiments are designed. This series is intended to be a vital link in that ongoing process of learning and discovery. If it facilitates schol arship, it will serve an important function."

This series was established to create comprehensive treatises on specific topics in developmental biology. Such volumes serve a useful role in developmental biology, which is a very diverse field that receives contributions from a wide variety of disciplines. This series is a meeting ground for the various practi tioners of this science, facilitating an integration of heterogeneous information on specific topics. Each volume is comprised of chapters selected to provide the conceptual basis for a comprehensive understanding of its topic as well as an analysis of the key experiments upon which that understanding is based. The specialist in any aspect of developmental biology should understand the experimental back ground of the specialty and be able to place that body of information in context, in order to ascertain where additional research would be fruitful. The creative process then generates new experiments. This series is intended to be a vital link in that ongoing process of learning and discovery."