Interest in the coronaviruses has never been greater. Their economic impact is considerable as they infect humans, livestock, poultry and companion animals. Murine hepatitis virus (MHV) infection of the mouse and rat central nervous systems are the subject of intense study; these investigations are providing insights into the potential role of viruses in human neurological diseases and, more generally, into mechanisms causing neurological damage. The single-stranded, positive-sense RNA genomes of two species of these enveloped viruses (IBV and MHV) have been cloned completely and one of them (lBV) sequenced in its entirety, revealing a genome size of some 27000 nucleotides. This has made possible more incisive investigations into the nature of those polypeptides, encoded by more than half of the genome, which are likely to contribute, in the main, to RNA polymerase/replicase activity. Intriguingly, ribosomal frameshifting is exhibited within the mRNA coding for these polypeptides. The cloning/sequencing phase of coronavirology for which the 1980's will be partly remembered, has provided a sound framework for furthex: studies of the virus structural proteins and also some provocative insights relevant to these studies. The large spike glycoprotein(s), responsible for membrane fusion and bearing important antigenic sites, varies amazingly in length and composition both within as well as between coronavirus species. Receptors on host cells have been identified. The integral membrane glycoprotein (M) has been shown to use internal hydrophobic sequences to direct translocation within membranes.

This is the first comprehensive work to review blood platelet biochemistry, physiology, pharmacology, and function. It provides up-to-date information on how platelets function, the biochemical mechanisms that modulate their physiology and function, as well as the pharmacology of platelet inhibitory drugs.

The third congress ofthe European Association for Veterinary Pharmacology and Toxicol ogy (EAVPT) was held in Ghent, Belgium, from 25 to 29 August 1985. Part I of the Proceedings of this congress contains the abstracts of all invited lectures, oral communi cations and poster communications, presented at the congress. The invited lectures are now published (this volume) in extenso as Part II of the Proceedings. The editors wish to thank all invited speakers for their active contribution to the success of the third congress of EAVPT. They are very grateful to Dr. P. De Backer for compiling all manuscripts, Dr. P. Lees for scientific amendments, Miss B. Vermeesch and Dr. R. Lefebvre for preparing the camera ready copy and MTP Press for literary advice and publishing. A. S. J. P. A. M. van Miert M. G. Bogaert M. Debackere xi Contributors AMEND J.F. Department of Anatomy and Physiology, Atlantic Veterinary College. University of Prince Edward Island. Charlotte town. P.E.I. CIA 4P3. Canada. ANIKA S.M. Department of Veterinary Physiology and Pharmacology. University of Nigeria, Nsukka. Nigeria. ARGENZIO R.A. Department of Anatomy, Physiological Sciences. and Radio logy, School of Veterinary Medicine. North Carolina State University. Raleigh, NC 27606. USA. ARONSON A.L. Clinical Pharmacology Unit. School of Veterinary Medicine. North Carolina State University, Raleigh. North Carolina 27606. USA. AUCOIN D.P. The Animal Medical Center. 510 E 62nd Street. New York. New York 10021. USA. xiii xiv COMPARATIVE VETERINARY PHARMACOLOGY, TOXICOLOGY AND THERAPY BAARS A.J."

Electron microscopy is frequently portrayed as a discipline that stands alone, separated from molecular biology, light microscopy, physiology, and biochemistry, among other disciplines. It is also presented as a technically demanding discipline operating largely in the sphere of "black boxes" and governed by many absolute laws of procedure. At the introductory level, this portrayal does the discipline and the student a disservice. The instrumentation we use is complex, but ultimately understandable and, more importantly, repairable. The procedures we employ for preparing tissues and cells are not totally understood, but enough information is available to allow investigators to make reasonable choices concerning the best techniques to apply to their parti cular problems. There are countless specialized techniques in the field of electron and light microscopy that require the acquisition of specialized knowledge, particularly for interpretation of results (electron tomography and energy dispersive spectroscopy immediately come to mind), but most laboratories possessing the equipment to effect these approaches have specialists to help the casual user. The advent of computer operated electron microscopes has also broadened access to these instruments, allowing users with little technical knowledge about electron microscope design to quickly become operators. This has been a welcome advance, because earlier instru ments required a level of knowledge about electron optics and vacuum systems to produce optimal photographs and to avoid "crashing" the instruments that typically made it difficult for beginners.

Why are books written? Since I have read many works by my colleagues with admiration, this question has always intrigued me. Further, writing a book takes a good deal of time and effort, and I had imagined that I would never undertake such a demanding task. A few unexpected events and circumstances have changed my mind. The first was the pleasant experience of editing Environmental Toxicology of Pesticides with Drs. Mallory Boush and Tomomasa Misato. This fine symposium volume occasioned many interesting responses, including a suggestion to prepare a more complete treatise on the grounds that such "proceedings" volumes, by their very nature, do not satisfactorily offer a complete and coherent description of the field, but cater chiefly to specialists. I myself prefer single-authored books for basic understanding of a scientific field. The second circumstance leading to the present volume was the avail ability of teaching notes from my course on the toxicology of insecticides. As the need to cultivate environmental awareness has increased, there has been a parallel increase in the enrolments of such courses both here and in other major institutions. Yet no comprehensive and up-to-date text has been available. The third factor which facilitated the effort was an especially pleasant sabbatical in Hawaii, where the availability of the excellent Hamilton Library at the University of Hawaii considerably eased my task."

This volume, the last in this series on cancer growth and Moreover, the current status of plant-derived vinca alka progression, is a companion volume to Volume IX and loids and non-alkaloid natural products is summarized. further explores established and novel approaches for the Advances in hyperthermia and additional approaches for therapy of patients with malignant neoplasms. The stra the therapy of malignancies are also presented. tegies reflected in these volumes are direct extrapolations The volume continues with chapters on bone marrow from the basic science of cancer biology, growth and pro transplantation as well as hematologic and nutritional sup gression described in earlier volumes of this series. Some port for the cancer patient. Blood pressure in the cancer approaches are directed towards the eradication or modifi patient, therapy for nausea and vomiting as well as pain are cation of the properties of heterogeneous malignant tumor discussed. The last chapter is devoted to the problems of the cells at various stages of tumor progression, while other terminally ill, including evaluations of the burden relatives approaches are directed towards modification of the host and friends of the cancer patient have to bear. antitumor defense systems, e. g., enhancement of host anti It is clear that important advances in the basic science of tumor immune reactivity."

9. REFERENCES 90 CHAPTER 9: OPPORTUNITIES FOR REPLACEMENT, REDUCTION AND REFINEMENT: HUMAN VIRAL VACCINES 93 1. INTRODUCTION 93 2. TESTS FOR EXTRANEOUS MICROORGANISMS 94 3. MUMPS VACCINE . . . 94 4. HEPATITIS B VACCINE 95 4. 1. Test for freedom from live hepatitis virus 95 4. 2. Potency test 95 5. INFLUENZA VACCINE 96 5. 1. Potency test 96 5. 2. Abnormal-toxicity test 96 6. MEASLES VACCINE. . . . . 96 6. 1. Tests for extraneous agents 97 6. 1. 1. Test for Mycobacterium tuberculosis 97 6. 1. 2. Test for extraneous viruses 97 6. 2. Abnormal-toxicity test 98 7. POLIOMYELITIS VACCINE. . . 99 7. A. Inactivated poliomyelitis vaccine 99 7. A. l. Production. . . . . . 99 7. A. 2. Test for residual live virus 99 7. A. 3. Tests for extraneous agents 100 7. A. 3. l. Test for Mycobacterium tuberculosis . . . . . 100 7. A. 3. 2. Test for extraneous viruses 100 7. A. 4. Tumourigenicity test. . . . . 100 XII 7 . A. 5. Potency test . . . . . . . 101 7. A. 6. Test for abnormal toxicity 102 7. B. Live, oral poliomyelitis vaccine 103 7. B. l. Test for extraneous agents 103 7. B. 2. Test for neurovirulence 105 7. B. 3. Test for abnormal toxicity 106 8. RABIES VACCINE 106 8. 1. Production 106 8. 2. Test for residual live virus 107 8. 3. Tests for extraneous microorganisms 107 8. 3. 1. Test for Mycobacterium tuberculosis 107 8. 3. 2. Tests for extraneous viruses 108 8. 3. 2. 1. In dogs 108 8. 3. 2. 2.

It is a great pleasure for me to introduce this great deal of information from various insti- manual for the diagnosis of parasites of domes- tutes and universities. tic animals. It is a unique publication in many The result is an impressively comprehen- respects. Books concerning parasitic anima I sive, beautifully illustrated and, above all high- diseases - comprehensive textbooks, but also ly serviceable manual. It is easy to consult. Its field manuals - abound. These generally deal systematic and colour-coded layout allows the with aetiology, c1inical signs and pathology, as user to steer swiftly and surely through a vast weil as control and treatment. However, while amount of information. Clinical pictures and methods for diagnosis are often mentioned, figures show the parasite stage of diagnostic these are rarely sufficiently practical and spe- interest, facilitating a rapid and accurate diag- cific to allow the person ne I in field laborato- nosis. The book has been designed to be used ries to reach a concise, rapid dia gnosis of the by veterinarians and technicians, by teachers parasite species involved in any particular case. and students - in fact, by anyone dealing with Parasitic Infections of Domestic Animals suc- the diagnosis of diseases in domestic animals. ceeds in redressing these shortcomings.

The articles published in this volume are based on the papers del ivered at a conference on the Role of Metal Ions in Biological Systems held November 20 and 21, 1972, at Argonne National Laboratory. The purpose of the conference was to present to an interdiscipl inary audience of physical scientists some recent developments illustrating the chemical and environ mental participation of the heavy metal ions in the biological system. The invited speakers at the conference are special ists in the fields they describe, and the articles presented here are at a level of interest to readers with backgrounds in physical sciences who are not necessari Iy doing research in the areas described. The articles are referenced through 1972, and in some cases early 1973, and thus should also be of value to research workers. It is hoped that the book wi II be of particular interest to chemists, biologists, workers in the fields of en vironmental science and publ ic health, as wei I as graduate and senior undergraduate students in these discipl ines. The conference was sponsored by the Central States Universities, Inc., a consortium of sixteen midwestern univer sities, the Center for Educational Affairs, Argonne National Laboratory, and the United States Atomic Energy Commission. It is my pleasure to thank the members of the conference committee for their ideas and active help in organizing the conference."

With the rapid spread of drug use and abuse in this country over the last decade, events relating to drugs have become increasingly prominent in the court of law as well as in society in general. It is anticipated that throughout the 1980s this problem will continue to be one of the major social problems in the United States. With the complexity of the Federal and state laws and their interrelationships, and with the increasing demand for the expert chemist or toxicologist, or both, in the courtroom, more education for these people relating to drugs must be implemented. The prosecuting and defense attorneys are also in need of accurate toxicological information to adequately handle cases in which drugs playa role. This book is intended to be a practical as well as an educational book-a resource tool for the active forensic chemist, as well as for the student. It is with the forensic chemist in mind that the material on controlled substances and substances found in cases of drug abuse has been arranged in a systematic order for quick and easy reference. This section includes synonyms, pharma ceutical preparations, biochemistry and/or pharmacognosy, toxicology and/or pharmacology, and how the substance is controlled under Federal law. Under the concept of scientific consideration as compared with the Federal law, this book enables one to deal with some of the major conflicts in the American legal system concerning scientific evidence and how it is presented in a court of law."

Tiselius demonstrated that the immunologically active components of immune sera migrated electrophoretically in the gamma globulin region. His findings illuminated the classic observations of Jenner regarding development of resistance to infection, and those of von Pirquet, Pasteur, and Arthus regarding the transfer and specificity of resistance. Conceptual integration of these observations provided the impetus for the present modern era of immunology. Subsequent to Tiselius's work, multiple, rapid advances have occurred in the study of congenital and acquired immune deficiency states in mice, chickens, and humans. These studies have readily demonstrated that the immunologic ability of an organ ism to protect itself from environmental influences is a prerequisite for survival. Indeed, this necessity for protection from microenvironmental influences has promoted the evolu tionary development of immunologic diversification, namely, host dependence upon a sophisticated, multifaceted network of cells and effector mechanisms responsible for the clearance and neutralization of toxins and potentially harmful pathogens. The obligate dependence of animals upon the functional integrity of their immunologic systems is illus trated by the ready invasion of ubiquitous organisms when the host is in a state of immune defense derangement. Nevertheless, derangements in immune function can range from par tial to complete and can be compatible with survival. The consequences of such derange ments run the gamut from subclinical disease to inevitable mortality."

A variety of metabolic processes are known to be intimately involved in the maintenance of cellular structure and function. It has also become clear that metabolic events involved in the synthesis and hydrolysis of ATP as well as for the synthesis of proteins and phospholipids are essential for cellular health. The regulation of cell function is generally achieved through participation of a wide variety of hormones and different signal transduction mechanisms for the activation/deactivation of some specific metabolic processes. In this regard cyclic AMP and calcium seem to play a crucial role. Various hormones are also known to affect the genetic machinery of all the cell; however, the exact signals for genetic control of cellular function are not well defined. In particular, the sequence of events concerned with remodelling of different types of cells under various pathological situations is poorly understood. In this book we have therefore dealt with some of these issues from biochemical, molecular biological, physiological, and pharmacological viewpoints. Special emphasis has been laid on understanding heart function and metabolism in health and disease in general, and cardiac hypertrophy, heart failure, and ischemic heart disease in particular. It is hoped that this multidisciplinary information will be of value to basic scientists and clinical investigators.

The field of genetic toxicology is a relatively new one which grew out of the studies of chemical mutagenesis and modern toxicology. Considering that systematic practices to detect chemical mutagenesis are only a little over thirty years old, this field has evolved very rapidly with an abundance of methods for identifying chemical mutagens. To evalulate the usefulness of the methods and to select the assay which will yield the most important information under practical conditions requires the broad experience such as that which Dr. Brusick has acquired over the last decade. Since this field is expanding very rapidly and new test ing methods are being recognized, it should be kept in mind that revisions may have to be made during the next five to ten years. The need for such a book has been obvious to us, particularly since training courses and workshops on genetic toxicology are being organized which find it beneficial to utilize established guidelines and since the reports in the literature do not always describe in detail how the work was carried out during laboratory testing. In addition to his broad background in genetics, Dr. Brusick has had much practical experience, having organized and directed the most extensive laboratory for mutagen testing. I am most pleased to see this volume, for which there is an ever-increasing need. Alexander Hollaender Associated Universities, Inc. 1717 Massachusetts Avenue, N.W."

The best protection against environmental mutagens is to identify them before they ever come into general use. But it is always possible that some substance will escape detection and affect a large number of persons without this being realized until later generations. This article considers ways in which such a genetic emergency might be promptly detected. A mutation-detecting system should be relevant in that it tests for effects that are as closely related as possible to those that are feared. It should be sensitive enough to detect a moderate increase in mutation rate, able to discover the increase promptly before more damage is done, responsive to various kinds of mutational events, and designed in such a way as to maxi- mize the probability that the Gause of an increase can be found. Methods based on germinal mutation necessarily involve enormous numbers of persons and tests. On the other hand, with somatic mutations the individual cell becomes the unit of measurement rather than the in- dividual person. For this reason, I think that somatic tests are preferable to germinal tests, despite the fact that it is germinal mutations which are feared.

The funny, touching and entertaining story of how Jo Hardy, the star of BBC2's Young Vets, gets to grips with animals big and small, friendly and not-at-all-happy, on the road to becoming a fully qualified vet. 'Stand well clear. Keep your eyes on them. Oh, and make sure you have insurance.' Not the most comforting words of wisdom, but probably the most useful for a trainee vet, Jo would say. From well-equipped surgeries to windswept hills and ramshackle barns, Jo has to be able to diagnose and treat any animal, at any time of the day or night. It's not quite as easy as James Herriot made it seem. Jo's final year of training saw her race from rectal examinations of cows to spine surgery on a Great Dane, and from treating an eventing horse with a heart problem to inserting a contraceptive implant into a monkey. And then there were the owners - the tough guy who sobbed when his cat was diagnosed with cancer, the woman who was convinced her dog was embarrassed by its stomach upset, and the farmer who loved his cows as much as anyone loves their pets. Gruelling days of animal treatments and visits combined with long nights of study and revision made Jo's final year of training the most demanding and rewarding year of her life. Her book tells of the highs and lows, the pets that stole her heart, and the lifelong friends that she made - with two legs and four.

Elastic filaments refer mainly to titin, the largest of all known proteins. Titin was discovered initially in muscle cells, where it interconnects the thick filament with the Z-line. Titin forms a molecular spring that is responsible for maintaining the structural integrity of contracting muscle, ensuring efficient muscle contraction. More recently, it has become clear that titin is not restricted to muscle cells alone. For example, titin is found in chromosomes of neurons and also in blood platelets. This topic is fast becoming a focal point for research in understanding viscoelastic properties at the molecular, cellular, and tissue levels. In titin may lie a generic basis for biological viscoelasticity. It has become clear that titin may hold the key to certain clinical anomalies. For example, it is clear that titin-based ventricular stiffness is modulated by calcium and that titin is responsible for the altered stiffness in cardiomyopathies. It is also clear from evidence from a group of Finnish families that titin mutations may underlie some muscular dystrophies and that with other mutations chromatids fail to separate during mitosis. Thus, it is clear that this protein will have important clinical implications stemming from its biomechanical role. One aspect of this field is the bringing together of bioengineers with clinical researchers and biologists. Genetic and biochemical aspects of titin-related proteins are being studied together with front-line engineering approaches designed to measure the mechanics of titin either in small aggregates or in single molecules.

The traditional approach to diagnosis of virus infectians by isolation of the causative virus is usually both slow and expensive. More recently, the emphasis has been on the direct detection of viruses or viral antigens in clinical specimens. This can be done using established techniques such as immunofluorescence or electron microscopy, or by newly developed biochemical methods. The purpose of this meeting was to review these and other developments in the laboratory diagnosis of virus infections. We would like to thank all those who contributed to the success of this meeting. In particular, we are grateful to the CEC for financial sponsorship, to Professor C. Dow, Director of the Veterinary Research Laboratories, for help in organising the meeting, and to Miss B. Hamilton for her excellent typing of the manuscripts. M S McNulty J B McFerran VII CONTENTS Page Preface V VIRAL DIAGNOSIS BY TIMMUNOFLUORESCENCE P. S. Gardner APPLICATIONS OF IMMUNOFLUORESCENCE IN VETERINARY VIRAL DIAGNOSIS M. S. McNulty and G. M. Allan 15 TAGGING OF VIRAL ANTIGENS USING IMMUNOPEROXIDASE . AND IMMUNOOOLD TEGINlQUES R. Ducatelle, F. Castryck and J. Hoorens 27 DETECTION OF BVD VIRUS IN VlRAEMIC CATTLE BY AN INDIRECT IMMUNOPEROXIDASE TEGINIQUE A. Meyling 37 VIRAL DIAGNOSIS BY ELECTRON MICROSCOPY J. D. Almeida 47 CAPTURE ASSAYS FOR THE DETECTION OF VIRUS-SPECIFIC IgM ANTIBODY R. S. Tedder 60 DETECTION . AND IDENTIFICATION OF PAPILLOMAVIRUSES IN BENIGN . AND MALIGNANT 'TIlmJRS OF CATTLE M. S. Campo 72 DETECTION OF VIRAL NUCLEIC ACIDS IN CELL CULTURES .

This publication contains the proceedings of a Seminar "Beef production from different dairy breeds and dairy beef crosses," held in Ireland on April 13-15, 1981, under the auspices of the Commission of the European Communities (CEC) as part of the European Communities (EC) programme for beef production research. The CEC wishes to thank those representatives of Ireland who took responsibility for the organisation and conduct of this Seminar, notably Professor E.P. Cunningham, Dr. G.J. More O'Ferrall (local organiser), Dr. Patricia McGlaughlin and In particular, thanks are due to Dr. McGlaughlin Mr. R. Barlow. and Mr. Barlow for their recording of the discussions. Professor Ian Gordon of the Faculty of Agriculture, kindly made available the facilities of Lyons House, University College, for the Seminar. Thanks are also accorded to the Chairmen of the Sessions Professor D. Smidt, Dr. R.B. Thiessen, Professor A. Neimann Sorensen, Professor E.P. Cunningham, and to all the participants who presented papers and took part in the discussions. X OBJECTIVES The aims of the Seminar were to review recent comparisons of Holstein and Friesian strains with other dairy breeds for beef and veal production; to look at the use of beef breeds for crossing on dairy herds in various EEC countries, and to examine the economic and genetic balance between milk and beef traits in dual purpose bull testing and selection."

Where do you begin to look for a recent, authoritative article on the diagnosis or management of a particular malignancy? The few general oncology textbooks are generally out of date. Single papers in specialized journals are informative but seldom comprehensive; these are more often preliminary reports on a very limited number of patients. Certain general journals frequently publish good indepth reviews of cancer topics, and published symposium lectures are often the best overviews available. Unfor tunately, these reviews and supplements appear sporadically, and the reader can never be sure when a topic of special interest will be covered. Cancer Treatment and Research is a series of authoritative volumes which aim to meet this need. It is an attempt to establish a critical mass of oncology literature covering virtually all oncology topics, revised frequently to keep the coverage up to date, easily available on a single library shelf or by a single personal subscription. We have approached the problem in the following fashion. First, by dividing the oncology literature into specific subdivisions such as lung can cer, genitourinary cancer, pediatric oncology, etc. Second, by asking emi nent authorities in each of these areas to edit a volume on the specific topic on an annual or biannual basis. Each topic and tumor type is covered in a volume appearing frequently and predictably, discussing current diagnosis, staging, markers, all forms of treatment modalities, basic biology, and more."

The twentieth century has seen a remarkable evolution of environmental health and environmental protection concerns and concepts in the United States. As a teacher of Environmental Health since the late 1950s, I have witnessed the many twists and turns that have marked the latter half of the century, and have had to seek continuously to explain these phenomena to my students in some rational manner. We have witnessed the following and more: great progress in controlling acute infectious diseases through successes in drinking water treatment and food processing; the emergence of greater concern with trace chemicals in air and water and their role in chronic disease causation; conflicting attitudes toward miraculous chemicals such as DDT (which promised relief from arthropod-borne scourges, then came to be seen as another chemical threat to our children and our environment); then the reemerging concern with infectious diseases precipitated by blood-borne pathogens such as HIV. All this occurred against a backdrop of scientific uncertainty and amid failures of risk assessment and risk communication, together with press sensationalism-from "mad cow disease" to "flesh eating" streptococci. No wonder the public is confused.

Take a disease of complex pathology with inflammatory and neoplastic features, which affects lymphoid and neural tissues, belonging to a disease group which killed one chicken in five, and which defied efforts to understand and control it for lOre than 50 years, and one can begin to appreciate the interest Marek's disease has received. Canpound these characteristics with the finding of the causal herpesvirus, its recog nition as the neoplasm first discovered to be so caused, and its pre vention by vaccination, and the special place of Marek's disease in veterinary medicine and comparative oncology becomes clear. This book sets out to provide an authoritative and corrprehensive account of knowledge of Marek's disease and its control. I hope that it will be of value to veterinary research workers, teachers and students who need information about the disease, to veterinarians, poultrymen and vaccine manufacturers who have to diagnose and control it, and to oncologists in other fields interested in comparative aspects. other reviews of the disease exist, of course, but this is the first multi authored book devoted to the subject."

The "Groupe International de Recherche sur l'Infinitesimal" (GIRI) was created in 1986 by Professor Madeleine Bastide and Doctor Rene Halm. Madeleine Bastide was its President for several years. The group comprises actually more than 100 researchers from different disciplines (physicians, chemists, biologists, pharmacologists, physicists, etc. ) from 22 different countries. The original aim, which, for the most part, has now been achieved, was to create a working group to exchange ideas and results concerning the effects of very low doses and high dilutions. Madeleine Bastide then proposed to publish a collection of the lectures given at their scientific meetings in a bilingual book (French and English) entitled "Signals and Images." The first volume was published in 1990 by the ATELIERS ALPHA BLEUE. It contains lectures on the new pharmacological approach and related concepts that were presented at the 3rd and 4th Symposiums held in Paris in 1989 and 1990. This volume treats the problem of the effects of very low doses and high dilution in in vitro and in vivo experimental models. It is conceivable that this effect, like that of elect- magnetic fields, is none other than an "ultra molecular" effect as shown in yet p- lished results. The effect could be interpreted as a piece of information, i. e. a signal whose transmission and perception remains to be elucidated. According to Madeleine Bastide "everything depends on the nature and quality of the information, signals and images.""

As editor I want especially to thank Dr. Ernst Freese for helpful co operation in preparing these volumes, and to express my appreclatlOn to Drs. Kurt Hirschhorn and Marvin Legator, the other members of the editorial board. Alexander Hollaender January 1971 Preface The purpose of these volumes is to encourage the development and ap plication of testing and monitoring procedures to avert significant human exposure to mutagenic agents. The need for protection against exposure to possibly mutagenic chemicals is only now coming to be generally realized. The recently issued Report of the Secretary's Commission on Pesticides and Their Possible Effects on Health (the Mrak Report-U.S. Department of Health, Education and Welfare, December 1969) has made an important start. Its Panel on Mutagenicity recommends that all currently used pesticides be tested for mutagenicity in several recently developed and relatively simple systems. Whether recommendations such as these are actually put into effect will depend on convincing government, industry, and the public that the problem is important, that the proposed tests would be effective, and that they can be conducted at a cost that is not prohibitive. Why is it important to screen environmental agents for mutagenic activity? To those who will read this book, the answer is self-evident. The sine qua non of all that we value and all that we are is our genetic heritage.