* This book is designed for the use of the advanced student and professional worker interested in the international scientific community, particularly those in the fields of agronomy, agricultural sciences, botany, biological sciences, natural products chemistry, pharmaceutical chemistry and bio­ chemistry. The purpose is to inform the reader about significant advances in the biology and metabolism of alkaloids in plants. Since alkaloids are generally referred to as "secondary metabolites," the reactions discussed are not, for the most part, involved with the main metabolic pathways. The reactions that we are interested in are pathways that have been developed for the formation of these secondary metabolites, using as their starting mole­ cules one of the compounds produced via a main or primary metabolic path­ way. The primary metabolic pathways are common to all plants, indeed to most living organisms, whereas the highly specialized branches leading to alkaloid formation are found in only about 10 to 20 % of the known plants. The reason for these diversities in plant metabolism is not clear; however, it seems likely that the formation of highly individualized and specialized pathways resulted as a response to the pressure of natural selection. Nevertheless, the genetic peculiarity that controls alkaloid production has provided many extremely interesting problems for scientists and consti­ tutes convincing evidence of nature's superior ability in biochemistry.