Among the fishes, a remarkably wide range of biological adaptations to diverse habitats has evolved. As well as living in the conventional habitats of lakes, ponds, rivers, rock pools and the open sea, fish have solved the problems of life in deserts, in the deep sea, in the cold Antarctic, and in warm waters of high alkalinity or of low oxygen. Along with these adaptations, we find the most impressive specializations of morphology, physiology and behaviour. For example we can marvel at the high-speed swimming of the marlins, sailfish and warm-blooded tunas, air breathing in catfish and lungfish, parental care in the mouth-brooding cichlids and viviparity in many sharks and toothcarps. Moreover, fish are ofconsiderable importance to the survival ofthe human species in the form of nutritious and delicious food of numerous kinds. Rational exploitation and management of our global stocks of fishes must rely upon a detailed and precise insight of their biology. The Chapman and Hall Fish and Fisheries Series aims to present timely volumes reviewing important aspects of fish biology. Most volumes will be of interest to research workers in biology, zoology, ecology and physiology, but an additional aim is for the books to be accessible to a wide spectrum ofnon specialist readers ranging from undergraduates and postgraduates to those with an interest in industrial and commercial aspects of fish and fisheries."

To humans, cold has a distinctly positive quality. 'Frostbite', 'a nip in the air', 'biting cold', all express the concept of cold as an entity which attacks the body, numbing and damaging it in the process. Probably the richness of descriptive English in this area stems from the early experiences of a group of essentially tropical apes, making their living on a cold and windswept island group half way between the Equator and the Arctic. During a scientific education we soon learn that there is no such thing as cold, only an absence of heat. Cold does not invade us; heat simply deserts. Later still we come to appreciate that temperature is a reflection of kinetic energy, and that the quantity of kinetic energy in a system is determined by the speed of molecular movement. Despite this realization, it is difficult to abandon the sensible prejudices of palaeolithic Homo sapiens shivering in his huts and caves. For example; appreciating that a polar bear is probably as comfortable when swimming from ice floe to ice floe as we are when swimming in the summer Mediterranean is not easy; understanding the thermal sensa tions of a 'cold-blooded' earthworm virtually impossible. We must always be wary of an anthropocentric attitude when considering the effects of cold on other species."

This volume focuses exclusively on those endocytic processes that sequester proteins by a selective, receptor-mediated mechanism. In such an endocytic process, cell surface receptors specifically bind protein ligands and localize them to specialized invaginations of the plasma membrane. These regions are coated pits, so named because they are lined on the cytoplasmic face with an ordered array of the protein, clathrin. It is this 'coat' which provides their characteristic electron microscopic image. Subsequently, these regions pinch off to form coated vesicles which rapidly lose their 'coat' and then fuse with other organelles or the plasma membrane. The hallmarks of, this process are the specific receptors, coated pits, coated vesicles and an ordered sequence of transit events leading to delivery to selected locations. Receptor recognition, specific disposition of the endocytosed ligand and the existence of recep tor-ligand complexes at highest density in coated pits define the process as selective and concentrative. This topic has received ever increasing attention during the past few years. The evolving mechanisms are especially exciting because they come at a time when the conventional views based on thermodynamic arguments suggest that proteins should not be able to cross into the cell. Receptor-mediated endocytosis, however, reconciles the view that biological membranes should be impervious to macromolecules with the evidence that certain mac romolecules do gain entrance into the cell. During the last few years this field has been stimulated by studies on the uptake and processing of low density lipoproteins (LDL) by cells."

Fluorescence microscopy images can be easily integrated into current video and computer image processing systems. People like visual observation; they like to watch a television or computer screen, and fluorescence techniques are thus becoming more and more popular. Since true in vivo experiments are simple to perform, samples can be directly seen and there is always the possibility of manipulating the samples during the experiments; it is an ideal technique for biology and medicine. Images are obtained by a classical (now called wide-field) fluorescence microscope, a confocal scanning microscope, upright or inverted, with epifluorescence or transmission. Computerized image processing may improve definition, and remove glare and scattered light signal. It also makes it possible to compute ratio images (ratio imaging both in excitation and in emission) or lifetime imaging. Image analysis programs may supply a great deal of additional data of various types, starting with calculations of the number of fluorescent objects, their shapes, brightness, etc. Fluorescence microscopy data may be complemented by classical measurement in the cuvette yr by flow cytometry.

This is an ideal book for graduate students and researchers interested in the aerodynamics, structural dynamics and flight dynamics of small birds, bats and insects, as well as of micro air vehicles (MAVs), which present some of the richest problems intersecting science and engineering. The agility and spectacular flight performance of natural flyers, thanks to their flexible, deformable wing structures, as well as to outstanding wing, tail and body coordination, is particularly significant. To design and build MAVs with performance comparable to natural flyers, it is essential that natural flyers' combined flexible structural dynamics and aerodynamics are adequately understood. The primary focus of this book is to address the recent developments in flapping wing aerodynamics. This book extends the work presented in Aerodynamics of Low Reynolds Number Flyers (Shyy et al. 2008).

In the first edition of The Enzymes of Biological Membranes, published in four volumes in 1976, we collected the mass of widely scattered information on membrane-linked enzymes and metabolic processes up to about 1975. This was a period of transition from the romantic phase of membrane biochemistry, preoccupied with conceptual developments and the general properties of membranes, to an era of mounting interest in the specific properties of membrane-linked enzymes analyzed from the viewpoints of modem enzymology. The level of sophistication in various areas of membrane research varied widely; the structures of cytochrome c and cytochrome b5 were known to atomic detail, while the majority of membrane-linked enzymes had not even been isolated. In the intervening eight years our knowledge of membrane-linked enzymes ex panded beyond the wildest expectations. The purpose of the second edition of The Enzymes of Biological Membranes is to record these developments. The first volume describes the physical and chemical techniques used in the analysis of the structure and dynamics of biological membranes. In the second volume the enzymes and met abolic systems that participate in the biosynthesis of cell and membrane components are discussed. The third and fourth volumes review recent developments in active transport, oxidative phosphorylation and photosynthesis."

As a food resource in both Eastern and Western countries, the eel is an important fish. Over the years, remarkable progress has been achieved in understanding the mysterious life cycle of eels that has fascinated scientists since the age of Aristotle. The spawning area of the Japanese eel was discovered and the migratory route of its larvae was elucidated. With the development of techniques for artificial induction of gonadal maturation, it became possible to obtain hatched larvae. Larval rearing to the leptocephalus stage, one of the most difficult tasks involved in eel culture, finally was achieved. By presenting these important breakthroughs, Eel Biology will be of great help in the development of effective management strategies for maintaining stable eel populations. With contributions by leading experts, this book is a valuable source for researchers as well as industry technicians in the fields of aquatic biology, aquaculture, and fisheries.

Various endogenous and environmental challenges of homoiostasis have resulted in the evolution of apparently quite different mechanisms for the same or similar functions in individual representatives of the animal kingdom. One of the prominent achievements of comparative physiology over the last few decades has been the description of regula- tory features common to many studied species beyond the extreme diversity of their morphological forms. Delineation offunctional princi- ples universally applicable to the physiology and biochemistry of living systems became often possible through technical advances in the devel- opment of numerous new techniques, in many cases modified and adopted from other fields of science, but also by approaching certain problems using multifactorial analysis. The advance in technology has facilitated studies of minute functional details of mechanisms, which finally lead to better understanding of generally similar functions, covered by the multiple developments of Nature as a response to an extreme variety of different conditions. Improved understanding of specific mechanisms, however, has presented new problems at the level of system integration. The importance of the integrative aspect became particularly apparent during an international symposium on 'Mecha- nisms of Systemic Regulation in Lower Vertebrates: Respiration, Circu- lation, Ion Transfer and Metabolism' (organized in 1990 by Norbert Heisler and Johannes Piiper at the Max-Planck-Institut fUr experimen- telle Medizin at Gottingen/Germany).

The dream of developing a biocomputer should not be dismissed as a sheer fantasy. Although there is naturally some doubt as to whether it is possible to design a computer using carbon-based components as in living organisms, instead of silicon-based components as in existing computers, the fact that an average brain often outperforms the most sophisticated computer in terms of the complexity of tasks, if not in terms of speed, is a living testimony to this possibility. The remaining question is to what extent a biocomputer can mimic a living organism and whether it is possible to design and fabri cate such a biocomputer within the foreseeable future. This volume does not attempt to provide immediate and exact answers to these questions but instead attempts to provide a vision and a progress report of the initial efforts. This volume is mainly a collection of papers presented at the Symposium on Molecular Electronics - Biosensors and Biocomputers, sponsored by the Divi sion of Biotechnology, Health and Environment of the Fine Particle Society, held from July 19-22, 1989 at the Society's 19th Annual Meeting in Santa Clara, California. Also included are articles contributed by those who planned to attend the conference but were unable to do so. The emergence of the field of molecular electronics is largely the consequence of one person's crusade, that of Forrest L. Carter.

Bruce E. Tabashnik and Richard T. Roush Pesticide resistance is an increasingly urgent worldwide problem. Resistance to one or more pesticides has been documented in more than 440 species of insects and mites. Resistance in vectors of human dise8se, particularly malaria-transmit ting mosquitoes, is a serious threat to public health in many nations. Agricultural productivity is jeopardized because of widespread resistance in crop and livestock pests. Serious resistance problems are also evident in pests of the urban environ ment, most notably cockroaches. Better understanding of pesticide resistance is needed to devise techniques for managing resistance (Le., slowing, preventing, or reversing development of resistance in pests and promoting it in beneficial natural enemies). At the same time, resistance is a dramatic example of evolution. Knowledge of resistance can thus provide fundamental insights into evolution, genetics, physiology, and ecology. Resistance management can help to reduce the harmful effects of pesticides by decreasing rates of pesticide use and prolonging the efficacy of environmentally safe pesticides. In response to resistance problems, the concentration or frequency of pesticide applications is often increased. Effective resistance management would reduce this type of increased pesticide use. Improved monitoring of resis tance would also decrease the number of ineffective pesticide applications that are made when a resistance problem exists but has not been diagnosed. Resistance often leads to replacement of one pesticide with another that is more expensive and less compatible with alternative controls."

This comprehensive treatise on the reticuloendothelial system is a project jointly shared by individual members of the Reticuloendothelial (RE) Society and bio medical scientists in general who are interested in the intricate system of cells and molecular moieties derived from those cells which constitute the RES. It may now be more fashionable in some quarters to consider these cells as part of what is called the mononuclear phagocytic system or the lymphoreticular sys tem. Nevertheless, because of historical developments and current interest in the subject by investigators from many diverse areas, it seems advantageous to present in one comprehensive treatise current information and knowledge con cerning basic aspects of the RES, such as morphology, biochemistry, phylogeny and ontogeny, physiology, and pharmacology as well as clinical areas including immunopathology, cancer, infectious diseases, allergy, and hypersensitivity. It is anticipated that, by presenting information concerning these apparently het erogeneous topics under the unifying umbrella of the RES, attention will be focused on the similarities as well as interactions among the cell types constitut ing the RES from the viewpoint of various disciplines. The treatise editors and their editorial board, consisting predominantly of the editors of individual vol and enormous task umes, are extremely grateful for the enthusiastic cooperation undertaken by members of the biomedical community in general and especially and Japanese Reticuloen by members of the American as well as European dothelial Societies.

The Intemational Meeting on Vitamin B6 and Carbonyl Catalysis took place on Capri, Italy from 22nd to 27th May 1994 and was organized in conjunction with the 3rd Symposium on PQQ and Quinoproteins. It was an extraordinary occasion for scientists from all over the world to meet and discuss new developments in these overlapping fields. Several sessions were dedicated to the molecular aspects of Vitamin B6 and Quinone dependent enzymes, as well as to the cellular, biomedical and nutritional aspects. The congress was inaugurated by Paolo Fasella in his capacity as General Director of Science, Research and Development of the Commission of the European Communities, with an overview on Intemational Scientific Collaboration. The scientific sessions started with a talk on the History of Vitamin B6 given by David Metzler who at the very last minute presented Esmond Snell's paper adding some personal remarks. Unfortunately, both Esmond Snell and Alton Meister had to unexpectedly cancel the trip to Capri. These proceedings contain the papers presented as oral contributions and a few selected poster presentations. The limited number of pages meant we could not publish many interesting poster presentations, including those selected for the three lively and exciting evening poster discussion sessions called by the organizers "Vino, taralli and ... discussion".

In some countries, especially on the European continent, there still exists a remarkable veal market. This type of meat production seems, irrespective of any economic forecasts, to remain unchallenged so long as consumers expect that restaurants should offer courses like "r6ti de veaux," "vitello a la casa" or "Kalbsschnitzel." Producers, at least since about the past 1-/2 decades, have been aware of the beneficial effect of anabolic agents in veal production. This is possible due to the lack of endogenous sexual hormones during the juvenile or prepuberal status of these animals. A discussion about the benefit / risk - evaluation in connection with the use of anabolic agents in general was promoted in recent years by the public. This concern occurred concomitantly with the detection of illegally treated veal calves and the occurrence of diethylstilbestrol (DES) residues in canned food containing veal. The aim of this paper is to summarize the present status of residue data in edible tissues and excreta in order to allow the evaluation of the risk (given in the paper of Hoffmann within this program) and to consider reasonable monitoring measures. We have to face the fact that without an efficient control system the illegal treatment of calves can not be excluded. Therefore, this paper will not only consider different compounds and formulations, but will also deal with practised routes of administration.

List of Participants 1 Hypoxia-Induced Intermitochondrial Junctions in the Rabbit Carotid-Body : An Ultrastructural and Experimental Study. A. VERNA. N. TALIB and A. BARETS. 11 Ultrastructural Studies of the Cat Carotid Body Perfused for Short Periods with Physiological Saline Solutions. R.G. O'REGAN. M. KENNEDY. D. COTTELL and S. FEELY. Morphological and Biochemical 19 Characteristics of the Laryngeal Nerve paraganglia. A. DAHLQVIST. S. HELLSTROM. B. CARLSOO. J.M. PEGUIGNOT and S. DOMEIJ. 29 Central Terminations of Carotid Body Chemoreceptor Afferents. D. JORDAN. S. DONOGHUE. R.B. FELDER and K.M. SPYER. 39 Vascular Geometry of Arterial Chemoreceptors: Learning about the Caritud Body by Studying paraganglia of the Superior Laryngeal Nerve D. M. McDONALD and AMY HASKELL. Altered Function of Cat Carotid Body 50 Chemoreceptors in Prolonged Hyperoxia. S. LAHIRI. E. MULLIGAN. A. MORASHI. S. ADNRONIKOU and M. SHIRAHATA. 59 Glycolysis as a Link for Chemoreception? MARCO A. DELPIANO. Spectrophotometric Studies on Carotid 69 Body Tissue. H. ACKER. C. EYZAGUIRRE. ATP Content in the Cat Carotid Body 78 under Different Experimental Conditions. Support for the Metabolic Hypothesis. A. onESO. L. AL~ffiRAZ and C. GONZALEZ. 91 pathways for Calcium Entry into Type I Cells: Significance for the Secretory Response. A. OBESO. S. FIDONE and C. GONZALEZ. Effects of Cyanide and Acetylcholine on 99 Extracellular K+ and Ca++ Activities in the Cat Carotid Body. R.G. O'REGAN and H. ACKER. Application of the Chemiluminescent 108 Method to Carotid Body for Detecting Choline and Acetylcholine. ARCADI GUAL and JORDI HARSAL.

Dr. BRUNO BLOCH, professor of the Dermatological clinic of Zurich, began a new era of eczema research by attempting to sensitize guinea pigs to primula. It was during this period that I had the pleasure of being Dr. BLOCH's chief resident, and could observe these experiments. It was only in 1955 that Dr. E. BUJARD, professor of Histology of the University of Geneva, Dr. R. BRUN, chief of laboratories of my Dermatology Department and I began to work in the field of experimental eczema on the nipples and flanks of guinea pigs. Besides these collaborators, to whom I am very grateful, a few others have participated in our experiments. Among these new co-workers the most im portant was Mrs. NICOLE HUNZIKER, chief resident of my clinic. From 1960 on, she worked on the eczema experiments with guinea pigs. Our research has been conside rably advanced by Dr. HUNZIKER. Untill now we have published 30 communica tions on this subject, but the publications about our results have been very short. It now seemed appropriate to publish a monograph and Dr. HUNZIKER undertook this very toilsome task. I would like to take this occasion to thank her for her many years of collaboration both in the clinic and in the laboratory. I am also very grateful to Professor BUJARD who, in spite of the fact that he is retired, continues to work with us. We continually profit from his great experience. Dr.

Discovering the secrets of animal movement and what they can teach us Insects walk on water, snakes slither, and fish swim. Animals move with astounding grace, speed, and versatility: how do they do it, and what can we learn from them? How to Walk on Water and Climb up Walls takes readers on a wondrous journey into the world of animal motion. From basement labs at MIT to the rain forests of Panama, David Hu shows how animals have adapted and evolved to traverse their environments, taking advantage of physical laws with results that are startling and ingenious. In turn, the latest discoveries about animal mechanics are inspiring scientists to invent robots and devices that move with similar elegance and efficiency. Integrating biology, engineering, physics, and robotics, How to Walk on Water and Climb up Walls demystifies the remarkable secrets behind animal locomotion.

If this were a traditional textbook of neuroanatomy, many pages would be devoted to a description of the ascending and descending pathways of the spinal cord and several chapters to the organization of the sensory and motor systems, and, perhaps, a detailed discussion of the neurological deficits that follow various types of damage to the nervous system would also be included. But in the first draft of this book, the spinal cord was mentioned only once (in a figure caption of Chapter 2) in order to illustrate the meaning of longitudinal and cross sections. Later, it was decided that even this cursory treatment of the spinal cord went beyond the scope of this text, and a carrot was substituted as the model. The organization of the sensory and motor systems and of the peripheral nervous system have received similar coverage. Thus, this is not a traditional text, and as a potential reader, you may be led to ask, "What's in this book for me?" This book is directed primarily toward those students of behavior who are either bored or frightened by the medically oriented texts that are replete with clinical signs, confusing terminology, and prolix descriptions of the human brain, an organ which is never actually seen in their laboratories. I should hasten to add, however, that this text may also serve some purpose for those who read and perhaps even enjoy the traditional texts.

B. Raymond Fink Sheldon Roth and Keith Miller have asked me to record that the Third Conference on Molecular and Cellular Mechanisms of Anesthesia was held in Calgary last May "in my honor. " Such was my dear friends' gracious way of continuing a series that began at the University of Washington, where I hosted two, four, or five previous ones, 1,3-6 depending 2 on how far back one wishes to count. At that, Seattle took up where Paris left off in 1951. These occasions create their own unforgettable memories. This book captures the fine, invigorating ambience of the University of Calgary and the exciting explorations and com panionship of a gathering in a frontier territory of neuroscience. So, floreant symposia. They have progressively refined the quarry, from pathway to synapse to lipoprotein membrane to receptor and single channel, in heuristic convergences of neuronal physiology, biochemistry, and pharmacology. Nevertheless, the anesthesiologist in me senses a certain disquiet, a certain claustrophobia provoked by the narrow confines of micropipettes. How much more tubular must tunnel vision become before the desired broad view emerges? At present, the advances in molecular neurobiology seem continually to increase the apparent complexity of the total problem and the conceptual distance between the reductionists in the laboratories and the holists in the operating rooms. Happily, what is also growing is the excitement in trying to bridge the gap. Perhaps it would be timely to regard general anesthesia not as a state but as a syndrome."

Indonesia possesses the second largest primate population in the world, with over 33 different primate species. Although Brazil possesses more primate species, Indonesia outranks it in terms of its diversity of primates, ranging from prosimians (slow lorises and tarsiers), to a multitude of Old World Monkey species (macaques, langurs, proboscis moneys) to lesser apes (siamangs, gibbons) and great apes (orangutans). The primates of Indonesia are distributed throughout the archipelago. Partly in response to the number of primates distributed throughout the Indonesian archipelago, Indonesia is classified as the home of two biodiversity hotspots (Wallacea and Sundaland). In order to be classified as a hotspot, an area must have a large proportion of endemic species coupled with a high degree of threat including having lost more than 70% of its original habitat. Two areas within Indonesia meet these criteria. The tremendous diversity of primates in Indonesia, in conjunction with the conservation issues facing the primates of this region, created a need for this volume.

"Gradually, a faint brightness appeared in the east, and the air, which had been very warm through the night, felt cool and chilly. Though there was no daylight yet, the darkness was diminished, and the stars looked pale. The prison, which had been a mere black mass with little shape or form, put on its usual aspect; and ever and anon a solitary watchman could be seen upon its roof, stopping to look down upon the preparations in the street . . . By and by the feeble light grew stronger, and the houses with their sign-boards and inscriptions stood plainly out, in the dull grey morning . . . And now, the sun's first beams came glancing into the street; and the night's work, which, in its various stages and in the varied fancies of the lookers-on had taken a hundred shapes, wore its own proper form - a scaffold and a gibbet . . . " (The Complete Works of Charles Dickens, Harper & Brothers, New York and London, Barnaby Rudge, Vol. II, Chapter XIX, page 164. ) Dickens describes an activity which takes place in the early morning hours, just before sunrise. As the day begins and people start to go about their business and get ready to watch the hanging, the hangman is ready with the gallows.

The present volume originated from the workshop "Transduction in Biological Sys tems," held at the Marine Biological Station of the Universidad de Valparaiso, Mon temar, Chile, May 23-30, 1988, and contains contributions from most of the partici pants in the workshop. The title of both the workshop and the book reflects accurately the central theme discussed during several days of intense debate and profound intellectual exchange in the peaceful environment offered by the central coast of Chile. It was apparent that the workshop was a great success-a sentiment expressed by many seasoned attendees, some of whom dared opinions as strong as "It was the best ever." There is no single reason to explain why this workshop was so successful. Certainly instrumental was the incredible effort displayed by the Chilean Organizing Committee in selecting adequate facilities and in organizing social events that supplemented the scien tific sessions and provided an authentic fraternal environment for the participants. Equally important were the foreign participants, who enthusiastically gave of their time to take part in the event, and the students, who came from Chile as well as from several other Latin American countries, and who applied the necessary pressure in their repeated demands for scientific clarity, accuracy, and sincerity."

This book has a dual purpose, to review in depth the control of fuel homeostasis in the brain and the role of the nervous system in the control of fuel deposition in the body. From the methodological point of view the emphasis is on the application of advanced technologies to assess fuel transport and brain metabolism, the role of peptides in the neuroendocrine system and the response of the brain to hypoglycemia. These technologies include positron emmission tomography, nuclear magnetic resonance, immunocytochemistry, molecular biology, autoradiography. To study fuel homeostasis in the body advanced tracer methods that include modelling are set out. From the pathophysiological point of view the emphasis is on abnormalities in stress, brain metabolism in diabetes, eating and degenerative disorders. This book contains contributions from endocrinologists, physiologists, neurologists, psychoneuroendocrinOlogists, biophysicists, biochemists and experts in nutrition. This authorship represents a unique diversity of researchers who, for the first time, cover comprehensively the interaction between the nervous system and fuel homeostasis, both in health and disease. We hope this book will be an important source of information for both researchers and practicing clinicians. Mladen Vranic Suad Efendic Charles Hollenberg v ACKNOWLEDGEMENTS The Symposium from which this volume arose (University of Toronto, June 27-28, 1990) was the first Toronto-Stockholm symposium on Perspectives in Diabetes Research. These Symposia are organized triennially by the Banting and Best Diabetes Centre, University of Toronto and the Department of Endocrinology, Karolinska Institute, Stockholm.

The biotechnological advances of recent years have put us on the brink of unprecedented gains in animal productivity. Manipulation of animal growth rate and composition of gain is now possible by a variety of techniques. Ex amples include ingestion of beta-adrenergic agonists, injection of somatotropin, castration, immunization, and gene insertion. Animal Growth Regulation ad dresses modem concepts of growth regulation with an emphasis on agricul turally important animals. This emphasis is not exclusive, as many situations exist in which the only information available was generated in other species, and this information has been included for the sake of clarity and completeness. However, because of the overall orientation of this volume, particular attention has been given to the regulation of skeletal muscle, adipose tissue, and bone growth. Certain hormones and growth factors have a profound influence on growth regulation and this basic physiological knowledge is being harnessed to maniplilate growth. Thus, considerable emphasis has been given to growth hor mone-somatomedinlinsulinlike growth factor regulation of cell and tissue growth. The involvement of peptides coded by protooncogenes and of negative growth regulators, such as transforming growth factor-l3, represents an emerging area of molecular biology wherein basic knowledge offers potential exploitation for growth manipulation. Opportunities also exist for regulation of protein turn over, especially from the standpoint of protein degradation. Therefore, a place was reserved for these topics in order to provide relevant basic knowledge."

In the mid-sixties, John Robson and Christina Enroth-Cugell, without realizing what they were doing, set off a virtual revolution in the study of the visual system. They were trying to apply the methods of linear systems analysis (which were already being used to describe the optics of the eye and the psychophysical performance of the human visual system) to the properties of retinal ganglion cells in the cat. Their idea was to stimulate the retina with patterns of stripes and to look at the way that the signals from the center and the antagonistic surround of the respective field of each ganglion cell (first described by Stephen Kuffier) interact to generate the cell's responses. Many of the ganglion cells behaved themselves very nicely and John and Christina got into the habit (they now say) of calling them I (interesting) cells. However. to their annoyance, the majority of neurons they recorded had nasty, nonlinear properties that couldn't be predicted on the basis of simple summ4tion of light within the center and the surround. These uncoop erative ganglion cells, which Enroth-Cugell and Robson at first called D (dull) cells, produced transient bursts of impulses every time the distribution of light falling on the receptive field was changed, even if the total light flux was unaltered."

Present knowledge of the mechanisms underlying any single sensory modality is so massive as to discourage effort directed towards completeness. The idea underlying the structure of this volume on "Sensory transduction" was to select just a few topics of general interest, which are currently being investigated and for which a reasonably clear picture is now available. During the last five years there has been a revolution in the way sensory physi ologists think about transduction, and a series of exciting advances have been made in understanding the basic processes of photo transduction, chemotransduction and mechan otransduction. It is clear that in many cases the fundamental processes by which nature attains optimization of performance are similar, and that they have much in common with more general processes of signal recognition by living structures. The molecular events underlying the detection of photons by visual cells, the recognition of a given molecule by a chemoreceptor, or the level of a hormone in the extracellular fluid by a target cell, are all very similar, and involve the activation of a sequence of events leading to a secon d messenger. The 20 papers that form the present volume cover various topics in the field of sensory transduction. They originate from the lectures, seminars and discussions which made up the XVIII Course of the International School of Biophysics held in Erice, 9th - 19th June 1988.