Recent Progress in Hormone Research, Volume 25 presents the proceedings of the 26th meeting of the Laurentian Hormone Conference held in Mont Tremblant, Quebec, Canada, on August 23-29, 1968. The book presents papers on reproductive endocrinology (i.e. a model for the regulation of ovulation in the rat; comparative aspects of uterine-luteal relationships), proinsulin (i.e. proinsulin and the biosynthesis of insulin), and the secretion of hormones by tumors of nonendocrine origin (i.e. clinical and laboratory studies of ectopic humoral syndromes). The text also includes papers on the ultrastructure of the endocrine glands; on the thyroid (i.e. studies of the thyroid iodide ""trap"" in human); on neuroendocrinology (i.e. the mammalian pineal as a neuroendocrine transducer), and on steroid hormones (i.e. metabolic events associated with steroid hydroxylation by the adrenal cortex; and steroid dynamics under steady-state conditions). Endocrinologists and people involved in hormone research will find the book invaluable.