ANNUAL REVIEWS INC. covers 27 subjects in its yearly critical reviews. Twenty of these subjects are in the life sciences, devoted to advances in the scientific understanding of the organism and its environment. Some of these life science topics are principally environmental (ecology, sociology, and public health); others are principally organismic (anthropology, biochemistry, biophysics, cell biology, entomology, genetics, immunology, neuroscience, animal physiology, plant physiology, psychology, and phytopathology). Four reviews (medicine, nutrition, pharmacology and toxicology, and microbiology) deal with both ecologic and physiologic aspects of the life sciences. Like Janus, the Roman god of doorways, they face two ways: inward and outward.

The Annual Review of Nutrition increasingly touches on all of the life sciences, particularly those that are interfacial with nutrition: medicine, microbiology, biochemistry, pharmacology, and toxicology. These sciences share the dictum of Paracelsus, "The dose makes the drug," and the observation that most biologically active molecules are required by cells at one dose but may be toxic at a higher dose.

Thus, the life sciences clearly form a seamless garment. Divisions within and outside the science of nutrition are arbitrary, and the concept of science as paniculate and overly reductionist is misleading. The response of organisms to nutrients, toxins, drugs, and microorganisms involves a whole range of physiologic responses, including those involving genetic, endocrinologic, and metabolic regulation. In fact, nutritional disease cannot be investigated properly without also examining the endocrine, genetic, and metabolic responses of the organism. Homeostasis preserves not only a constant extracellular environment but also the capability for maximum change in the intracellular environment. Modern advances in genetics, endocrinology, cell biology, and the neurosciences have made these responses more understandable to all biologists.

Volume 9 of the Annual Review of Nutrition has a broad range of reviews in the fields of experimental, clinical, and public health nutrition that overlap many areas of ecology and physiology, particularly genetics. The reviews of nutritional deficiency diseases include ones on iodine, vitamin A and trace mineral and protein-calorie malnutrition in infants as influenced by weaning practices and milk composition. The promotion of nutritional disease by achlorhydria in adults and the thyroid response to protein-calorie malnutrition are also reviewed.

Contributions from genetics are exemplified this year by two reviews on genetic factors in heart disease and one on differentiation of adipose tissue. Biochemical reports include one on selenium metabolism and selenium-containing proteins in microorganisms, one on the mitochondrial fuel supply, one on fatty acid receptors, one on glutathione metabolism, one on vitamin transport, one on calcium as an intracellular messenger, and two on lysosomes. The sugar alcohols are reviewed as part of nutritional pharmacology. Reviews on lactose intolerance, the role of dietary protein in renal disease, and the effect of injury on metabolic fuel selection complete this volume.

Volume 9 is a concrete example of the integration of all of the life sciences into the study of nutrition. The prefactory chapter by Dr. Snell is a masterful account of his studies of the metabolism of microorganisms in elucidating the function of the B-complex vitamins as well as providing microbiologic assays for these vitamins in blood and urine of animals. It is a classic account of the unity and diversity of biochemical pathways from microorganism to human. Again, I thank my associates on the Editorial Committee, the consultants who aided us in assembling the list of topics and authors, and the authors who contributed the excellent reviews that appear in Volume 9. Ms. Ann McGuire in Palo Alto, California, deserves our thanks for her important work in producing this volume.

Robert E. Olson, Editor