This volume on the evolutionary aspects of neuro-endocrinology is based on contributions from the 7th International Symposium on Neurosecretion, which took place in Leningrad, on August 15-21, 1976. The book deals with three major approaches in elucidating the general evolutionary events responsible for the structure and function of neurosecretory elements: (1) phylogenetic development of neurosecretory elements and their function, (2) ontogenetic development of neurosecretory elements and their function, and (3) the role of neuroendocrine mechanisms in realizing species adaptation, i.e., mechanisms causing the evolutionary process. Half of the chapters deal with evolutionary aspects. The majority of them are concerned with the role of different types of neurosecretory cells in the regulation of homeostasis and of the function of endocrine glands, primarily that of the adenohypophysis. The other half are concerned with various aspects of neurosecretion, featuring two main problems: (1) investigation of neural and hormonal mechanisms regulating the function of neurosecretory cells and neurosecretory centers as a whole, and (2) investigation of the role of neurosecretory systems in the regulation of adaptive reactions of the organism.