Comparative Endocrinology, Volume II, Part One: Invertebrate Hormones: Tissue Hormones provides readers with some basic knowledge of animal morphology, physiology, and chemistry; a systematic and comprehensive account of endocrine principles from the comparative point of view. It can therefore be hoped to present a critical and up-to-date picture of the comparative aspects of endocrinology to the medical scientist and zoologist generally, and to furnish an adequately documented background to the research worker who is beginning to take an interest in one of the many endocrine systems described. The subject matter has been divided into three sections. The largest—which forms the contents of the first volume—deals with hormones originating in well-defined glandular organs and tissues and also reviews the relationships between the central nervous system and these endocrine complexes. The second section (Volume II, Part 1) discusses hormonal systems of invertebrates, and the third (Volume II, Part 2) contains a description of neurohormones and tissue hormones.