Zoophysiology – serie

The new edition of P.J. Bentley's established text describes the physiological mechanisms utilized by different vertebrate species to adapt to the differences and vicissitudes of water and salt availability in their natural environments. The book is especially concerned with the roles of endocrine glands in coordinating and maintaining such osmoregulation. It provides information about the environmental stresses and physiological and endocrine processes involved in the osmoregulation in each phyletic order of the vertebrates, and it describes the physiological adaptations they have evolved to foster their survival in osmotically hostile habitats. The second edition provides a comprehensive update utilizing the considerable amount of new data which have been collected over the past years. From a review of the previous edition: "I strongly recommend it as an essential reading and reference book for younger and older workers alike". Nature

The factors which set the metabolic potentials of animals - the physicochemistry of the respiratory medium utilized, the phylogenetic level of development, the habitat occupied, and the life-style pursued -, have been the most decisive determinants of the constructions of the gas exchangers. After molding the most appropriate respiratory devices and adjusting them in accord with the individual needs for molecular oxygen, animals occupy different ecological niches and even share common environments. From the perspective of respiration, they have very few choices: there are only two fluid respiratory media and essentially two habitable spaces - water and air. They must adapt to either and in rarer cases to both.

This work documents various studies on hearing in marsupials and relates this information to their vocal behaviour. The organization of the brain auditory pathways of marsupials is compared with those of eutherian mammals and related to the structure of the periphery. The information on marsupials provides insight into the development of the brain and hearing in other mammals.

The opportunity to prepare a second edition of a book that was originally written 30 years ago has provided me with both a challenge and a source of pleas­ over ure; the former as it needed to be spatially constrained within its original limits. Nevertheless, over 1000 references have been added. I must apologize to the many biologists whose contributions could not be included. I have attempted to keep the original format and historical perspective. The information has been princi­ pally described within the context of each phyletic group of the vertebrates and their habitats. Each chapter is reasonably self-contained, but appreciation of mate­ rial in later chapters, as often indicated, can be amplified by reference to Chap­ ters 1 and 2. Information that was provided in tables in the first edition has now often been summarized in the text. Reviewing the work of earlier contributions to this field of study has evoked many pleasant memories of friends and acquain­ tances, some deceased, events and occasions. It has been a particular pleasure to perceive the consequences of such observations and know some of the answers to the questions that they raised. A new generation of such questions has now emerged, which is one of the reasons for preparing this summary. I would like to thank Professor Don Bradshaw for suggesting that this book may be welcome and Springer-Verlag for making it possible.

This monograph evolved from years of research into the auditory pathway and hearing of many species of marsupials. Its function is to give biologists, in par­ ticular neurobiologists, a broad description and review of what is known of the auditory sensory capacities and processing mechanisms in this large order of mammals. My initial interest in marsupials developed from collaborative work with Dr. Richard Gates at Monash and Melbourne Universities in the 1970s and by curiosity as to whether concepts about the auditory system was stimulated stemming from experiments mainly on domestic cats could be extended to mam­ mals of other orders. My subsequent interest in Australian marsupials, aroused by collaboration with Dr. John Nelson at Monash University in the 1980s and 1990s, concerned their auditory systems and behavior per se and not as primitive cousins of eutherians. More recently, I have collaborated with Dr. Bruce Masterton at Florida State University in studies of New World marsupials. His sad death in 1996 has robbed neurobiologists of one of our most provocative thinkers and hypothesis testers. I would like to thank the Department of Physiology at Monash University for making many facilities available to me, the National Health and Medical Research of Australia and the Australian Research Council for providing funds for Council research, and Jill Poynton and Michelle Mulholland, who illustrated this volume.

"Amongst animals, diversity of form and of environmental circumstances have given rise to a multitude of different adap­ tations subserving the relatively unified patterns of cellular metabolism. Nowhere else is this state of affairs better exem­ plified than in the realm of respiration". Jones (1972). The field of comparative respiratory biology is expanding almost exponentially. With the ever-improving analytical tools and methods of experimentation, its scope is blossoming to fascinating horizons. The innovativeness and productivity in the area continue to confound students as well as specialists. The increasing wealth of data makes it possible to broaden the information base and meaning­ fully synthesize, rationalize, reconcile, redefine, consolidate, and offer empirical validation of some of the earlier anecdotal views and interpretations, helping resolve the issues into adequately realistic and easily perceptible models. Occa­ sional reflections on the advances made, as well as on the yet unresolved prob­ lems, helps chart out new grounds, formulate new concepts, and stimulate inquiry. Moreover, timely assessments help minimize isolation among investiga­ tors, averting costly duplication of effort. This exposition focuses on the diversity of the design of the gas exchangers and gives a critical appraisal of the plausible or constrained the evolvement of respiration. The factors that have motivated cause-and-effect relationship between the phylogenetic, developmental, and en­ vironmental factors, conditions, and states which at various thresholds and under certain backgrounds conspired in molding the gas exchangers is argued.

The renin-angiotensin system and the mechanisms regulating this system developed during the adaptive evolution of verte­ brates, along with many other systems involved in the in­ tegrated survival of the organism. Because animal species have evolved from common ancestral populations, a basis for the comparison of body structures and physiological processes ex­ ists among animal groups belonging to different classifications. The comparative approach provides a better understanding of the structure and function of adaptive systems and facilitates the development of general principles governing these systems among animal groups; further, this approach reveals significant characteristics specific to certain animal groups. As the evolu­ tion of adaptation of animals to environmental conditions is explored, directions for future research are suggested. In this book, advances in research on the renin-angiotensin system are described with emphasis on the comparative aspects. However, since studies on the renin-angiotensin system of birds, reptiles, amphibians and fishes are limited compared with those con­ ducted in mammals, in some chapters descriptions are con­ cerned primarily with mammals. It has taken a long time to write this volume, and the topic is a broad one, with new data always emerging; therefore, certain aspects, and sometimes the most recent information, may not be included. Chapters 1-3 and sections 8. 1-8. 4,8. 6, 8. 7 were written by H. K. ; Chapters 4-7 and Section 8. 5 by Y. T. ; Chapter 9 was written by both authors. H. Uemura, M. Nozaki, Y. Okawara, We are indebted to Drs.

The Amazon is a giant piece of "amphibian" land which is the result of complex geological and evolutionary processes. The number of living beings in such a land is difficult to estimate. The interactions between these organ­ isms and the environment are fascinating but barely understood. These features lured us to the Amazon in 1981. However, soon after, we realized that the dimensions of these interactions were overwhelming. This book is designed to review aspects of the physiology and biochemistry of fishes of the Amazon. The description of the pulsative nature of the environment and the distinct features of the ichthyofauna of the Amazon were central to the main goal. Nevertheless, any complete view is limited by the magnitude of the intraspecific variability coupled with the complex fluctuations of the environment. Thus, we have placed an emphasis on respiratory physiology and biochemistry. The reference list was made as complete as possible, particularly regarding special publications not readily available. We hope that this book is useful for comparative physiologists, tropical biologists, and the people interested in interactions between organ­ isms and their environment. We are grateful to many people who contributed to the making of this book. Our initial ideas were influenced by Drs. Arno Schwantes, Maria Lufza Schwantes, Jose Tundisi, Anna Emflia Vazzoler, and Naercio Menezes.

Biological effects of magnetic fields have been studied in many animals and plants. The magnetic fields were of a wide intensity range and, as alternating fields, of a wide frequency range and of a variety of impulse shapes. Effects on the cellular level, on bio­ chemical processes, growth and development, interactions with physiology, sensory input, reflexes and rhythm control, to name just a few, have been reported. Numerous magnetically induced changes in behavior have also been described. Recently, the amount of literature covering biological effects of magnetic fields has been rapidly increasing. By now it has grown to such an extent that it can no longer be covered in one volume. Most reviews specialize and focus on particular aspects and/or types of fields or effects. For example, the book edited by MARET et al. (1986) gives an overview on biological effects of steady magnetic fields, MISAKIAN et al. (1993) reviewed those of extremely low frequency magnetic fields, focusing on in vitro effects. BERN­ HARD (1992) reported on 'electromagnetic smog' in view of pos­ sible effects on human health and well-being, and a series of papers edited by AMEMIYA (1994) summarizes Japanese research on effects of electromagnetic fields ranging from extern ely low to ultra-high frequencies. TENFORDE (1979) and ADEY (1981) sum­ marized and discussed tissue interactions, REITER (1993a) neu­ roendocrine and neurochemical changes associated with various kinds of electromagnetic fields. The book edited by KIRSCHVINK et al.

Invertebrate animals represent a diversity of solutions to life's challenges. Success in a wide range of environments has been achieved by an almost bewildering range of invertebrate body forms. These body forms are reflected in the wonderful diversity of their nervous systems. Despite this apparent diversity, studies of the development of invertebrates and vertebrates are yielding common themes at the molecular level. Likewise, the phenome­ non of neural regeneration is based upon properties intrinsic to neurons and responses to a remarkably conserved chemical lan­ guage. This monograph focuses on the diversity and commonal­ ity of responses to neural injury. The rough and tumble of life may frequently damage some part of the body, particularly the appendages or sensory sys­ tems. The nervous system is usually involved in repair of other body systems and often may itself require repair. Some animals are particularly successful in regenerating the nervous system or body parts. We particularly marvel at these feats of regeneration because we human beings are not particularly successful, despite our relatively long life and the advantages that would seem to accrue from such repair. It is no wonder that we would hope to learn the secrets of the more successful animals and strive to emulate them! Mechanisms of neural regeneration are often more acces­ sible in invertebrates than in vertebrates because questions of specificity are more easily addressed using the identifiable neu­ rons of the relatively simpler nervous systems of some inverte­ brates.

I had the good fortune to first meet Gerald Kuchling in 1985 when attending a conference held at the CNRS research centre, the Centre d'Etudes Biologiques des Animaux Sauvages (CEBAS), which is a wonderful scientific field station tucked away in the Foret de Chize, not far from the southwest town of Niort in France. The topic of the meeting, which included many invited overseas scientists, was "Physiological Regulations as Adaptive Mechanisms", and it was superbly organised by Ivan Assenmacher and Jean Boissin who together edited the impor- tant volume of papers published from the meeting. My stay in Chize was, unfor- tunately, cut short as the wife of a very close colleague died on the night of the first day of the meeting and I had to return to Paris to assist with the funeral -but not before I had the chance to meet and talk with Gerald. He was presenting some of his work on a terrestrial tortoise (or turtle depending upon one's origins) - Testudo hermanni - a species that is now extremely rare in France but still relatively abundant in the then Yugoslavia.Gerald had been working in Yugoslavia, collecting blood samples from both males and females in an attempt to decipher details of its reproductive biology.

As the title indicates, the theme of this book is the functions of biochromes in animals. Recent works on zoochromes, such as those of D. L. Fox (1953), H. M. Fox and VEVERS (1960) and VUILLAUME (1969), have been concerned primarily with the chemical nature and the taxonomic distribution of these materials, and although function has been considered where relevant this has not been the centre of interest and certainly not the basis for the arrangement of the subject matter. Functional significance is a profitable focus of interest, since it is the one theme which can make biochromatology a discrete and integral subject, and because it is the main interest in all biological fields. At present chromatology seems to be a particularly schizoid subject since it is clear that in metabolic functions biochromes are acting in a chemical capacity whereas integumental pigments function mainly biophysically, in neurological and behavioural contexts. It is profitable to attempt an integration by studying the functions of as many chromes as possible, from all aspects.

Mention the words 'arthropod cuticle' to most biologists and they usually provoke a glazed expression. This is because the cuticle is commonly regarded as an inert substance. It is hoped that this book will dispel this fallacy. The study of cuticle in its proper context now involves many of the wider aspects of biology which are currently in vogue (e. g. how a hormone like ecdyson induces a specific enzyme like dopa decarboxylase; the unsolved major problem of cell gradient and polarity; the involvement of cyclic AMP in hormonal mechanisms; the extra­ cellular control of cuticular enzymes, of the mechanical proper­ ties of cuticle structural proteins, and of the orientation of fibrous molecules; and the relation of chromosome puffing to the synthesis of specific proteins). Studies on cuticle demand a variety of techniques, and examples of the following are illustrated in this book (fluorescence, phase contrast, polariza­ tion and Nomarski interference microscopy; infrared absorp­ tion; transmission and scanning electron microscopy; autora­ diography analyzed by electron microscopy; negative staining in the electron microscope; optical diffraction, high angle X-ray diffraction, low angle X -ray diffraction and selected area electron diffraction). I am well aware that the biophysical parts of this book are less incomplete than other aspects. A developmental biologist or a biochemist would have further elaborated other parts ofthe subject matter. Only one previous author, RICHARDS (1951)hasdevoted a book to arthropod cuticle.

On being asked to write a book on migration and homing in animals, intended as an introductory text to inform and stimulate both students and non-specialists, I saw the following alternatives for an outline: (1) I could discuss known or hypothetical mechanisms of orientation, and enumerate animals known or thought to use these mechanisms in migration and homing. (2) I could discuss the known feats of orientation by animals under field observation (e. g. migration), following some practic­ able order, with a subsequent discussion of the attempts at and possible success in elucidating the basic mechanisms of orientation. Both alternatives have obvious disadvantages. (1) would suffer from the fact (a) that very few orientation mechanisms (such as the sun, star, or magnetic compass) have been firmly established and (b) that for many animals the modes of orienta­ tion are unknown; therefore, for many animals whose consider­ able feats of orientation are well known, an appropriate alloca­ tion could not be made. With (2) the disadvantage is that due to the complexity of animal movements, it is difficult to find some relevant order and that in many animal groups discussions of certain known mechanisms such as the sun com­ pass would recur. I have selected outline (2) as the much lesser evil. The discussion pursues a compromise between taxonomic order and similarity in feats of orientation or methodological approaches chosen by the various investigators.

Predation is an ecological factor of almost universal importance for the biol­ ogist who aims at an understanding of the habits and structures of animals. Despite its pervasive nature opinions differ as to what predation really is. So far it has been defined only in negative terms; it is thought not to be par­ asitism, the other great process by which one organism harms another, nor filter-feeding, carrion-eating, or browsing. Accordingly, one could define predation as a process by which an animal spends some effort to locate a live prey and, in addition, spends another effort to mutilate or kill it. Ac­ cording to this usage of the word a nudibranch, for example, that feeds on hydroids would be a predator inasmuch as it needs some time to locate col­ onies of its prey which, after being located, scarcely demand more than eating, which differs little from browsing. From the definition just proposed consumption of the prey following its capture has been intentionally omit­ ted. Indeed, an animal may be disposed of without being eaten. Hence the biological significance of predation may be more than to maintain nutrition­ al homeostasis. In fact, predation may have something in common with the more direct forms of competition, a facet that will be only cursorily touched upon in this book.

This book has been written mostly within sight of wild African ungulates, at the research center in Tsavo East National Park, V oi, Kenya. While this had many positive aspects, there were also a few drawbacks. The main one of these is the fact that Voi is not exactly at the hub of scientific activity, even if we restrict ourselves to African ungulates. Thus, whereas I had felt initially that I was sufficiently familiar with ethological work on these animals to write a useful review, it soon became woefully evident that this assumption was erroneous. Over the last few years studies on African ungulates have pro­ liferated and results are being published in journals almost all over the world. My location in East Africa was sometimes less than ideal with respect to access to the most recent literature, and I depended to a considerable extent on the goodwill of colleagues in giving or lending me relevant papers. I am happy to report that I received a great deal of support and cooperation in this respect. Nevertheless, I may have over­ looked some important papers inadvertently; their authors should not feel slighted by such omissions, which only reflect availability of literature to me. Readers may also notice a considerable geographical bias in favor of East Africa, at the expense of other African regions, particularly South Africa.

Writers on arthropod water relationships range from bio­ physicists and biochemists to population ecologists-a fact that gives cause to wonder whether the field is already too heterogeneous to be written about in a single book by a single author. I have partly avoided the problem by concentrating largely on physiological mechanisms and by omitting most aspects of behavioural regulation and most aspects of heat balance and body temperature, except when these impinge directly on water balance. Even within this limited field there has been a lot of work during the past twenty years, as a result of which some problems have been solved (or at least more clearly defined), and many others have been opened up. On the whole there has been a welcome change to a more rigorous experimental approach and it is now possible for water balance people to state their problems in physiological terms. Good progress has been made towards understanding the mechanisms involved in nearly all avenues of water uptake and loss, although problems indeed remain. The cuticle has yielded part of its secrets to electron micrography, but ex­ ploration by means oflipid biochemistry among other techniques is necessary for a real understanding of cuticle permeability.

With the increasing numbers of research workers and groups of investigators devoting themselves to the ecology of carabids I felt that the time had come to take stock of the existing knowledge in this field and to endeavour to weld my personal results and those of other workers into a comprehensive picture. It was with these aims in mind that the following study was conceived. A further goal was to attempt to show to what extent research on carabids can contribute to the larger fields of research encompassing ecology, ethology and evolution. In my opinion the investigations on carabids permit us to draw conclusions of general applicability and, as such, comparable with those made in recent years upon other groups of animals. I am well aware of the risk involved nowadays in attempting, on one's own, to integrate results from a wide variety of scientific disciplines into a meaningful whole, and for this reason I am always grateful for corrections and for additional information. It is impossible for me to mention by name all of the col­ leagues who have given me their support in the preparation of the book. Reprints of their publications have been placed at my disposal by almost all of the authors cited, as well as by others whose names and works have been omitted merely in order to prevent the book from taking on encyclopedic pro­ portions. I am nevertheless indebted to them all for their cooperation.

Fish are extremely successful vertebrates. Because of a long and divergent history they are now found in almost every conceiv­ able aquatic habitat. This radiation has been accompanied by great diversity in structure, physiology, and behaviour. Despite this variability, fish must solve a number of basic problems that are common to all animals. The most important of these are: (1) to find and ingest appropriate food; (2) to avoid predation; and (3) to reproduce. The main purpose of this book is to describe the variety of behavioural strategies that fish use in coping with these problems. My approach has been to draw together material from both field and laboratory work that is widely scattered in the litera­ ture. The major emphasis is on field studies, since my main concern is with adaptive solutions to problems, and I believe these are most likely to be correctly perceived by workers who are familiar with the natural ecological setting of their animals. Of course, many details of behaviour cannot be seen and quantified adequately in the field, and therefore I have not ignored laboratory studies. However, even here I have concen­ trated on work that illustrates the variety of solutions that fish use to solve the three basic problems. Much important work, for instance on causation, development, and learning, is not included.

The approach of this treatise is physiological throughout. In the eyes of the author it answers the rhetorical question raised by Maurice B. Visscher at the Physiology Congress in Washington D. C. in 1968: Does physiology exist? What he meant by this question was whether the fields of cellular physiology and physiology of the various organ systems had become so large that physiology as such had vanished. The firm answer is that physiology does indeed exist. Although it is important to study physiological problems at the subcellular level, it is importan- and equally difficult - to study organ regulation at the cellular level, organ interaction, and integration into the whole organism. An account of avian osmoregulation from an integrated point of view is attempted in this book. Since reading Homer W. Smith's From Fish to Philosopher and August Krogh's Osmoregulation in Aquatic Animals verte­ brate osmoregulation has been in the center of the author's interest. The focus was set on avian osmoregulation after personal contact with the School of Krogh when working in the laboratory of Bodil M. Schmidt-Nielsen. The fundamental concepts and isotope techniques introduced by Hans H. Ussing have been of constant inspiration. An excellent example for the study of osmoregulation at the cellular level was given by the late Jean Maetz. The writing of this book was suggested by Donald S. Farner who is thanked for thorough editorial assistance, and especially with help in the subtle semantic peculiarities of the English language.

The intention of this book is to offer a comprehensive description and discussion of autonomic nerve function in the vertebrates from several points of view. Sections on anatomy, biochemistry of the transmitter substances and the structure, physiology and pharmacology of the different types of autonomic neurons have been included, together with chapters dealing with the autonomic nervous control of some organs and organ systems in the different vertebrate groups. Although knowledge in several of these areas is based primarily on studies of mammals, a certain emphasis has been placed on the autonomic nerve functions in the non-mammalian vertebrates to describe, from a comparative physiological point of view, the adaptations and possible "phylogenetic trends" in the development of the autonomic nerve functions in the vertebrates. It is very obvious that the literature created by the vigorous research activities within the fields of autonomic nervous anatomy, histochemistry, biochemistry, pharmacology and physiology is vast indeed, and not all aspects of the subject may have received fair treatment in the present volume. With an analogy from astronomy, it is hoped that the mass compressed into this book has reached the level of an energy-emitting neutron star, rather than the black hole which would be the result of compressing too large a mass.

Chance Favors Only the Prepared Mind How does a scientist go about the task of pushing back the curtains of the unknown? Certainly the romance of tackling the mysteries of nature provides the motivation, for who would not be inspired by the remarkable life history of this romantic beast, the salmon. After living in the Pacific Ocean for several years, salmon swim thousands of kilometers back to the stream of their birth to spawn. I have always been fascinated by the homing migration of salmon. Noone who has seen a 20-kilogram salmon fling itself into the air repeatedly until it is exhausted in a vain effort to surmount a waterfall can fail to marvel at the strength of the instinct that draws the salmon upriver to the stream where it was born. But how does it find its way back? I was puzzling over this problem during a family vacation in 1946. Inspired by the work of the great German Nobel Laureates, Karl von Frisch and Konrad Lorenz, I had been conducting research with my graduate student Theodore Walker, since 1945, on the ability of fishes to discriminate odors emanating from aquatic plants. Von Frisch had studied schooling minnows and discovered that, if broken, their skin emitted a con specific chemical substance, termed Schreckstoff, which caused other members of its school to disperse and hide.

Physiology and biochemistry of male reproductive function and semen became the main area of my research in 1944, after my attention was finally diverted frorp. animal cells in general, to mammalian spermatozoa specifically~ Ever since, the interest has remained largely focussed on reproductive probletns in mammals, the work continuing mostly at the University of Cambridge, where I was privileged to hold also the Marshall­ Walton Professorship in Physiology of Reproduction. This work led to the publication of three books, The Biochemistry of Semen (Methuen 1954), The Biochemistry of Semen and of the Male Reproductive Tract (Methuen 1964) and lately, in co­ authorship with my wife, Dr. Cecilia Lutwak-Mann, Male Re­ productive Function and Semen - Themes and Trends in Phys­ iology, Biochemistry and Investigative Andrology (Springer­ Verlag 1981). In 1960, thanks to the Lalor Foundation, I was able to avail myself for the first time of a chance to visit the Marine Biological Laboratory at Woods Hole and there to take part in a study of reproduction in marine animals. Ever since, first as Visiting Professor of Biology at the State University of Florida, and later as the Walker Ames Professor and frequent visitor to the Department of Zoology at the University of Washington in Seattle, it has been my good fortune to sustain this pew interest and to pursue it further.

Adaptation to altitude hypoxia is characterized by a variety offunctional changes which collectively facilitate oxygen trans­ port from the ambient medium to the cells of the body. All of these changes can be seen at one time or another in the course of hypoxic exposure. Yet, as already stressed (Hannon and Vogel, 1977), an examination of the literature gives only a sketchy and often conflicting picture of the exact nature of these changes and how they interact as a function of exposure duration. This is partly because of the limited number of variables explored in a given study, but it is also attributable to differences in experimental design, differences among species in susceptibility to hypoxia, nonstandardized experimental conditions, lack of proper control of physical (e. g. , temperature) and physiological variables (e. g. , body mass), failure to take measurements at key periods of exposure, and gaps in knowledge about some fundamental mechanisms. Furthermore the available data on animals native to high altitude are meager and/or inconclusive. Extensive further work under well-controlled experimental conditions is required before a detailed picture can be made. Nevertheless, it has been a guiding principle in the prepara­ tion of this monograph rather to summarize the vastly dis­ persed material that constitutes the comparative physiology of adaptation to high altitude into a coherent picture, than to provide a comprehensive survey of the field.

Fish migration is important and spectacular. Migratory fish gather energy in one portion of the environment and transport it to other areas, where it often becomes available to humans or to other elements in the ecosystem. Migration brings fish into situations that allow easy harvest as they concentrate along migration routes. Their journeys also make them vulnerable to human intereference at critical points along their route. Salmon, for example, may harvest plankton in the open ocean and transport that food energy to coastal and inland regions, where it is captured by fisheries or deposited in inland streams and utilized by the flora and fauna of the region. These salmon are able to complete journeys of thousands of kilometers from their natal streams to oceanic feeding grounds and back to the same home streams, an accomplishment that strains our credi bili ty . We now understand some of the timing and guiding stimuli used in these migrations, and mechanisms can be logically proposed, on the basis of the established abilities of fishes, to account for the unexplained portions of the migrations. There is no single factor guiding these fish. Instead, they are dependent on the presence in their environment of a great variety of appropriate orienting and timing stimuli. These stimuli are vulnerable to human interference. The more widespread and easily available the information on these requirements, the more readily fish can be protected from such interference.

In addition to the more or less static properties of the environ­ ment, plants and animals must cope with its temporal variations. Among the most conspicuous temporal changes to which organisms are exposed are periodic phenomena generated by the rotation of the earth about its axis, its revolution around the sun, and the more complex movements of the moon in relation to both sun and earth. The first two of these astronomical cycles are basic to the familiar daily and annual rhythms, respectively, in the environment. The third generates somewhat more complex cycles, such as those in moonlight and variations in tides. These environmental cycles have provided challenges and opportunities for organisms to adjust their physiology and behavior to them. Indeed, the predictability inherent to these periodic processes has enabled organisms to evolve innate endogenous rhythmic programs that match the environmental cycles and allow, in a variety of different ways, adjustment of biological activities to the cycles of environmental changes. The endogenous nature of rhythmicity was first clearly recognized in the 1930's in daily periodicities, the most widely distributed and best investigated class of biological rhythms of this type. In the 1950's, demonstrations of endogenous tidal and lunar rhythms, which occur in some littoral and marine organisms, ensued. Another decade passed before endogenous annual periodicities were first demonstrated unambiguously.

Interest in comparative acid-base physiology has considerably grown during last decades even in the absence of major technical or conceptual advances. This is firstly because it has become clear that the extracellular acid-base state reflects the performance of many exchange functions at the organism level: respiration and ventilation of the gas exchange surfaces, metab­ olism, iono-and osmoregulation. Such functions are much in­ fluenced by ambient conditions, and the measurement of acid­ base parameters thus provides useful information about the organism's responses to environmental challenges. Secondly, many processes at the molecular level are now known to be pH­ sensitive, and acid-base regulation thus appears to be a major requirement for the functional integrity of cells and organisms. How extracellular acid-base balance can be maintained in a wide variety of animals living in different conditions is the sub­ ject of this book. The approach is comparative and environ­ mental throughout. All body fluids share similar buffer proper­ ties, and common physicochemical principles apply to any acid­ base system. However, in accord with differing designs and con­ straints along animal evolution, varying effector organs and mechanisms are at work to maintain an appropriate acid-base state in the organism. Particular emphasis is placed on the fun­ damental differences between water and air breathers and on the acid-base and respiratory problems arising at the transition from an aquatic to a terrestrial life. Also the complex array of factors influencing the acid-base state in water-dwelling animals is thoroughly discussed.

As far as we are aware, this is the first attempt to cover the com­ parative physiology of the pancreatic islets in a monograph. The topics discussed would probably have sufficed to fill about half a dozen monographs, a matter that becomes obvious from a look at the Contents. Hence, we have tried to present the ma­ terial more in the form of a digest, to emphasize evolutionary perspectives, to point out critical issues, and to identify challenging topics for future research. This approach required an arbitrary reduction of the num­ ber of references, and we therefore join the chorus of recent authors who beg their colleagues for understanding if some of their publications do not appear in the bibliography. Keeping up with the current literature was like fighting one of those monsters that grow a couple of new heads for each one that is cut off. Nevertheless, we hope that we have covered most of the key publications up to the autumn of 1986. We gratefully acknowledge the advice of many colleagues, and in particular the invaluable criticisms of Robert L. Hazelwood and Erika Plisetskaya. Special thanks are due to the series editor, Donald S. Farner, for his patience and guidance, both of which were fresh proof of his legendary diplomatic skills. Finally, we wish to thank Dr. D. Czeschlik and his staff at the Springer Verlag for their patience and support. Philadelphia, PA AUGUST EpPLE Greenville, NC JACK E. BRINN September 1987 v Contents Chapter 1. Introduction .......................... .

This volume emphasizes the comparative approach to under­ standing vertebrate renal function. I am convinced that this approach is of particular value in understanding both the details of renal function at the cellular and subcellular levels and the renal role in regulating fluid volumes and solute concentrations. My exposure to this approach first occurred during a student research experience in the laboratory of Wilbur H. Sawyer, who also provided an introduction to the works of Homer W. Smith and August Krogh. The importance of this approach was reinforced by doctoral and postdoctoral research in the laboratory of Bodil Schmidt-Nielsen. It has been confirmed through years of personal experience since then. My research and my understanding of renal function have been aided through the years by collaboration and discussion with numerous students and associates. Of particular impor­ tance in developing my views on comparative renal function, and especially on the relationship of structure to function, has been my long association with my colleague and friend, Eldon J. Braun. Donald S. Farner, who suggested the writing of this volume, provided valuable editorial assistance. Much of my personal research in this area has been supported over the years by grants from the United States National Science Foundation and National Institutes of Health. The writing of this volume was completed while I was in Wiirzburg, Federal Republic of Germany, supported by a Senior U.S. Scientist Award from the Alexander von Humboldt Foundation.