The subject of this book is neuroendocrinology, that branch of biological science devoted to the interactions between the two major integrative organ systems of animals-the endocrine and nervous systems. Although this science today reflects a fusion of endocrinology and neurobiology, this synthetic ap proach is relatively recent. At the beginning of the 20th century, when the British physiologists, Bayliss and Starling, first proposed endocrinology to be an independent field of inquiry, they went to great lengths to establish the autonomy of chemical secretions in general and their independence from nervous control in particular (Bayliss, W. M. , and Starling, E. H. , 1902, The mechanism of pancreatic secretion,]. Physiol. 28:325). They argued with Pav lov, who said that there was a strong influence of the nervous system on the gastrointestinal phenomena the endocrinologists were studying. For several decades, the English physiologists prevailed, at least in the West; and Pavlov's critique was not taken to heart by the practitioners of the newly emerging discipline of endocrinology. Through the work of Harris, the Scharrers, Sawyer, Everett, and others, there has been something of a scientific detente in the latter half of this century; the hybrid field of neuroendocrinology is now regarded as one of the corner stones of modern neural science and is of fundamental importance in basic and clinical endocrinology.