Compared with forces occurring in soil mechanics problems in civil engineering, the forces that are applied to soil in farming operations generally have a short duration, less than a few seconds, a small loaded area, no more than a few square decimeters, and small intensities, 10 bar being a high value. On the other hand, soil properties vary widely between those of a weak mud and a stone-like dry soil. Tillage and related applications of force to soil are practiced worldwide in farming. Tillage operations are performed on one hectare of land for every three human beings. This means that for the food production for each individual daily, something like one cubic meter of soil is stirred, or about 20 times his body weight. Theoretical knowledge of this most common human activity, which largely determines the surface shape of the fertile part of the earth, is still very limited. In this book the authors have tried to give an outline of the present state of the art. One of the starting points was a course in soil dynamics taught by the authors at the Agricultural University at Wageningen, The Netherlands. We hope to reach interested readers who have no more theoretical knowledge than high school level, as well as readers who want to go beyond the level of a third year university student. For the chapter on wheels and tires we received substantial support from F. G. J. Tijink of the Tillage Laboratory at Wageningen.

Latest techniques for the analysis of plant cell or tissue structure and the registration of physiological pathways are topics of this volume. The subjects include: - Laser Doppler Vibrometer Measurements of Leaves; - Laster Physical Methods. Laser Microprobe Mass Spectrometry; - Triplet States in Photosynthesis: Linear Dichroic Optical Difference Spectra via Magnetic Resonance; - Fast Atom Bombardment Mass Spectrometry; -Microdissection and Biochemical Analysis of Plant Tissues; - Photoacoustic Spectroscopy - Photoacoustic and Photothermal Effects; - Membrane Operational Impedance of Spectra of Plant Cell.

Since the founding of the People's Republic of China in 1949there has been a rapid advance in climatology in China. The number of climatological stations has increased from less than 100 to more than of Chinese climatologists covers various 2,000, and the research work fields. The climate of China is no longer just a description of the average weather for an area or locality, but covers many fields such as the monsoon climate, the fluctuation of climate, the spatial and temporal variations of the climatic elements and physical and dynam ic climate. Four books on the climate of China, written in Chinese, have been published so far. There is, however, no excellent book written in English on the climate of China, although Volume 8 of the World Survey oj Climatology, dealing with the climates of northern and eastern Asia, edited by H. Arakawa in 1969, contains a chapter on the climate of China and Korea written by LE. M. Watts. The data sources for China are based mainly on observations from 1940-1952 and the climatological charts of China published by the Central Weather Bureau of China in 1953 and 1955. This monograph on The Climate ojChina by Prof. Dr. M. Dom ros and Prof. Peng Gongbing is the first comprehensive and advanced book in English on the climate of China."

It is apparent that wilt diseases continue to be a major problem in crop production because of the number of crops affected, the number and genetic variability of pathogens involved, and their widespread occurrence throughout tropical and temperate regions under a variety of cropping systems. It is also apparent, however, that new understandings and approaches, often in combinations not previously discerned, offer exciting new prospects for research, understanding and practical control methods. The current state-of-the-art and fields for further studies were discussed by researchers actively engaged in a wide range of areas from ecological studies of physical and biological factors in the host-parasite-environmental interactions in the soil, through physiological and biochemical studies of host-parasite recognition and interaction that determine relative colonization of the host, through genetic-molecular studies of these interactions, to the most practical field studies of disease control.

Global attention in scientific, industrial, and governmental commUnItIes to traces of toxic chemicals in foodstuffs and in both abiotic and biotic environ ments has justified the present triumvirate of specialized publications in this field: comprehensive reviews, rapidly published progress reports, and archival documentations. These three publications are integrated and scheduled to pro vide in international communication the coherency essential for nonduplicative and current progress in a field as dynamic and complex as environmental con tamination and toxicology. Until now there has been no journal or other publica tion series reserved exclusively for the diversified literature on "toxic" chemicals in our foods, our feeds, our geographical surroundings, our domestic animals, our wildlife, and ourselves. Around the world immense efforts and many talents have been mobilized to technical and other evaluations of natures, locales, magnitudes, fates, and toxicology of the persisting residues of these chemicals loosed upon the world. Among the sequelae of this broad new emphasis has been an inescapable need for an articulated set of authoritative publications where one could expect to find the latest important world literature produced by this emerging area of science together with documentation of pertinent ancil lary legislation."

This thorough study is an assessment of the risks involved with the deliberate release of microorganisms modified by means of genetic engineering. Major emphasis is on European cooperative research projects such as the ones on Rhizobium and Baculovirus. Further contributions cover aspects of soil microbiology, genetic transformation in soil, molecular and plasmid genetics, horizontal spread of plasmids, as well as administrative, regulative and legal aspects in relation to possible releases.

By their powers of reason scientists will be able to extract from nature the answers to their questions. From: Critique of Pure Reason, 1781 Immanuel Kant (1724-1804), German Philosopher History is a composite of stories. The history of the biological disciplines has been written by all those who opened the gates of new knowledge by generating ideas and the experiments to support them. Previous authors have attempted various approaches to the history of virology, as is reflected in the numerous books and book-series issuing from the publishing houses. This volume is an attempt at a compre hensive yet compact survey of virology, which has meant penetrating the rigid limits of the separate disciplines of biology in which virologists have worked. Writing this history of experimental virology was really a search for the origins and for vital signposts to portray the wide scope of the knowledge attained thus far. This was done in com plete awareness of the fact that every presentation depends heavily upon the perspective of the observer, and of necessity communi cates only a part of the whole. The present scientific story hopes to recount the most important knowledge achieved during this past century - the first century of the exciting developments in virology."

An extraordinary development of the knowledge, concepts and biomedical applications has occurred during the past two decades in the biological sciences, including the Reticuloendothelial Sys- tem (RES). For example, it is now widely recognized that distinct classes of cells are involved in the recognition of "exogenous" invaders of the body such as microorganisms and other foreign an- tigens, as well as of "endogenous" parasites represented by trans- formed neoplastic cells and altered "self" antigens. Prominent among cell populations involved in such recognition of antigens and subsequent immune responses are those constituting the RES. In recent years, there has been much discussion and indeed contro- versy as to what constitutes such a system and even whether the term "RES" is appropriate. Some investigators feel that the phago- cytes are the most important cells of the RES as they playa major role in the defense mechanism of the host. Mononuclear phagocytes include tissue macrophages ~s well as circulating monocytes and their precursors. Although phagocytosis is a major functional ac- tivity, it is only one of their several functions. The important role of phagocytes and other mononuclear cells in antibody forma- tion, cell-mediated immunity, specific and non-specific resistance to microorganisms and tumor cells, as well as homeostatic adjust- ments in general has become the focus of attention for many inves- tigators.

Worldwide concern in scientific, industrial, and governmental com munities over traces of toxic chemicals in foodstuffs and in both abiotic and biotic environments has justified the present triumvirate of specialized publications in this field: comprehensive reviews, rapidly published progress reports, and archival documentations. These three publications are integrated and scheduled to provide in international communication the coherency essential for nonduplicative and current progress in a field as dynamic and complex as environmental contamination and toxicology. Until now there has been no journal or other publication series reserved exclusively for the diversified literature on "toxic" chemicals in our foods, our feeds, our geographical surroundings, our domestic animals, our wild life, and ourselves. Around the world immense efforts and many talents have been mobilized to technical and other evaluations of natures, locales, magnitudes, fates, and toxicology of the persisting residues of these chemicals loosed upon the world. Among the sequelae of this broad new emphasis has been an inescapable need for an articulated set of authorita tive publications where one could expect to find the latest important world literature produced by this emerging area of science together with documentation of pertinent ancillary legislation."

The recogmtIon of the microcirculation as an ideal interdisciplinary meeting place for the life sciences is really a postwar phenomenon. The European and the American Societies more than any other organizations launched the idea, and the success of the European Society's International Meetings gave impetus to a growth of interest from a handful of specialists to the wide interdisciplinary study which microcirculation now represents. The meeting held in Canada in June 1975 was, however, the first truly international meeting devoted to the microcirculation. It, too, was a success from every point of view, and the exchange of knowledge and new ideas was rewarding. It is our present hope that the tradition of European meetings with their characteristic European flavor will continue, but larded by larger, international congresses conceived on a worldwide basis. For the present conference we were fortunate in the presence of Dr. B. Zweifach. He was once referred to as the "father of the microcircula tion." This claim, unfortunately, I cannot accept. That honor probably belongs to Harvey, who by one of the most brilliant strokes of inductive reasoning in medical history inferred the existence of capillaries though he could not see them. Ben Zweifach's role was rather that of the midwife, presiding at the birth rather than the conception. The baby he delivered long years ago has since thriven lustily and its growth is in no small measure due to the continuing zeal of Zweifach and his associates."

Acid rain is a serious international environmental problem. Scandinavian forests have suffered especially severe damage, and have been the focus of considerable research on the causes and impacts of atmospheric pollution. This book presents the results of long-term studies on acid rain in Norwegian forests. This research examined soil chemistry and biology; the impacts of acid rain on tree growth and nutrition; and its influence on ground vegetation, fungi, and seedling germination and development. Long-Term Experiments with Acid Rain in Norwegian Forest Ecosystems is a lasting contribution to the literature on acid precipitation, and will be of interest to researchers in ecology, air pollution, forestry and environmental chemistry.

This book consolidates the descriptive results of a pantropical project called Agroforestry Systems Inventory (AFSI), undertaken by the International Council for Research in Agroforestry (ICRAF) from 1982 to 1987. Since agroforestry was a relatively new term when the project was initiated, the main objective was to increase the understanding of and provide a state-of the-art information base on existing agroforestry systems. Therefore, the project was designed to systematically collect, collate, synthesize, and dissem inate information on existing agroforestry systems in developing countries. One of the major results of the project, descriptions of existing agroforestry systems, was published as a series of articles in Agroforestry Systems. These system descriptions form the bulk of this book. Other products of the project include a microcomputer database on agroforestry systems, practices and components, and voluminous unpublished reports and records. Perhaps the title of the book is misleading in that the book does not include or cover all existing agroforestry systems in the tropics and geographical regions in the tropics. Additionally, some of the systems described are outside the tropical boul;ldaries of 23. 5" Nand S latitudes. For the purpose of this book, the word tropics is used in a general sense to also include subtropical developing countries that have agro-ecological and socio-economic character istics and land-use problems similar to those of the countries within the geographical limits of the tropical belt."

During the last decade, forest decline has become increasingly apparent. The decline in forest health was often reported to be associated with air pollution. The present study on Norway spruce stands in the Fichtelgebirge analyses various processes interacting within forest ecosystems. It covers transport and deposition of air pollutants, the direct effects of pollutants on above-ground plant parts, the responses of soil to acid rain, and the changing nutrient availability, and the accompanying effects on plant metabolism and growth. The role of fungi, microorganisms and soil animals in the decline of these stands is also assessed. The volume is concluded with a synthesis evaluation of the influence of different factors, and their interactions on forest decline.

Biologically active compounds isolated from microorganisms continue to be vital to the development of new drugs and agricultural chemicals. This book was prepared by current and past members of the laboratory of Dr. Satoshi Omura of the Kitasato Institute in Japan. Dr. Omura and his colleagues have discovered and studied a number of important antibiotics, and in their work they have pioneered new methods for screening microbes for interesting and important compounds. This book presents strategies and methods for identifying novel molecules with several types of biological activity. In addition, the book discusses the identification of microbial compounds of agrochemical importance, presents information on chemical screening methods, and concludes with chapters on microbial strain selection, fermentation technology, and genetic engineering of antibiotic-producing microorganisms. This book will be of great interest to scientists working in the very active and competitive fields of antibiotic and agrochemical discovery.

ing damage ranged from odor. to general visual appearance. Attributes of seedling quality are categorized as either to cutting buds. to scraping bark to detect dead cambium. performance attributes (RGP. frost hardiness. stress resistance) One nursery reported using frost hardiness as an indicator of or material attributes (bud dormancy. water relations. nutrition. when to begin fall lifting. but none reported using it as an morphology). Performance attributes are assessed by placing indicator of seedling quality before shipping stock to customers. samples of seedlings into specified controlled environments and evaluating their responses. Although some effective short 23.4.3 Stress resistance cut procedures are being developed. performance tests tend Only three nurseries measure stress resistance. They use to be time consuming; however, they produce results on whole the services of Oregon State University and the test methods plant responses which are often closely correlated with field described in 23.2.3. One nursery reported that results of stress performance. Material attributes. on the other hand. reflect tests did not agree well with results of RGP tests and that RGP only individual aspects of seedling makeup and are often correlated better with seedling survival in the field. Most stress poorly correlated with performance. tests are conducted for reforestation personnel rather than for Bud dormancy status seems to be correlated. at least nurseries."

The "International Symposium on Scleroderris Canker of Conifers" held June 21-24, 1983 in Syracuse, New York was the result of mutual interest expressed by the USDA Forest Service, the Canadian Forestry Service, and the State Uni versity of New York College of Environmental Science and Forestry (SUNY ESF). The Symposium was an official function of the working party canker diseases (Scleroderris), Subject group S.2.06.02 Division II IUFRO. We wish to express our thanks to the USDA Forest Service, Research and the Canadian Forestry Service for financial support of the program, and SUNY ESF for hosting the Symposium. A major research program was launched in 1977 to study the biology of the European strain as found in North America. Support for this research resulted from spec i a 1 fund ing by the Congress of the United States to the USDA Forest Service, North Central Forest Experiment Station. Most of these funds were released as cooperative research grants to universities in the Lake States and the northeast. Many of the research papers delivered at this Symposium are the direct result of these research grants. While the Symposium deliberately emphasized the North American experience 'with Gremmeniella abietina in order to provide a focus for the meeting, we were anxious that this Symposium would also include studies from other countries.

The quality of human life has been maintained and enhanced for generations by the use of trees and their products. In recent years, ever rising human population growth has put a tremendous pressure on trees and tree products; growing awareness of the potential of previously unexploited tree resources; and environmental pollution have both accelerated the development of new technologies for tree propagation, breeding and improvement. Biotechnology of trees may be the answer to solve the problems which can not be solved by conventional breeding methods. The combination of biotechnology and conventional methods such as plant propagation and breeding could become a novel approach to improving and multiplying a large number of the trees and woody plants. So far, plant tissue culture technology has largely been exploited by commercial companies in propagation of ornamentals, especially foliage house plants. Generally, tissue culture of woody plants has been recalcitrant. However, limited success has been achieved in tissue culture of angiosperm and gymnosperm woody plants. A number of recent reports on somatic embryogenesis in woody plants such as Norway spruce (Picea abies), Loblolly pine (Pinus taeda), Sandalwood (Santalum album), Citrus and mango (Mangifera indica), offer a ray of hope for inexpensive clonal propagation for large-scale production of plants or 'emblings' or somatic seedlings; protoplast work; cryopreservation; genetic transformation; and synthetic or artificial or manufactured seed production.

Although over 40 years have passed since Jacobs (1945) convincingly established the basic radial pattern of residual growth stress in growing trees, yet this phenomenon is still not widely appreciated in wood science and technology circles. This is in spite of the fact that the presence of these stresses of sizeable magnitudes has long been recognized as a primary cause of shakes and splits in logs as well as the warping of lumber sawn in the green condition. The presentation of the subject of growth stresses in trees presents some special problems due to the wide range of specialists who potentially might have an interest in the subject. For example, tree physiologists interested in questions such as the relation of mechanical stress to stem taper and the role of reaction wood and gravity forces in determining tree crown form encounter growth stress models. Silvi culturists interested in the relation ofthinning practices to wood quality find that wood properties are correlated with growth stress levels which are in turn significantly changed by cutting practices. Wood techno logists interested in the relation of residual growth stress gradients in green logs to the dimensional quality of sawn and seasoned lumber are forced to take a more quantitative approach to the effect of growth stresses than might have been the case in the past."

DEVELOPMENT AND DISTURBANCE IN AMAZON FORESTS Contrasting Impressions 6 2 The rain forests of the Amazon Basin cover approximately 5.8 x 10 km (Salati and Vose 1984). Flying over even just part of this basin, one gazes hour after hour upon this seemingly infinite blanket of green. The impression of immen sity is similar when viewed from the Amazon River itself, or from its tributar ies. From a hammock on the shaded deck of a riverboat, the immensity of the forest presents an incredible monotony as one view of the shoreline blends unnoticeably into another. From both perspectives, the overwhelming reaction to the sea of trees that stretches from horizon to horizon is a sense of the vastness of the rain forest. In September 1985, I got a different impression of the rain forest. Several students and I journeyed in a self-propelled car along the single-track railroad that stretches almost 1000 km from the Carajas iron ore mine in the rain forest of Para State, Brazil, all the way to Sao Luis on the coast (Fig. 1.1)."

This conference represents the first time in my life when I felt it was a misfor tune, rather than a major cause of my happiness, that I do conservation work in New Guinea. Yes, it is true that New Guinea is a fascinating microcosm, it has fascinating birds and people, and it has large expanses of undisturbed rainforest. In the course of my work there, helping the Indonesian government and World Wildlife Fund set up a comprehensive national park system, I have been able to study animals in areas without any human population. But New Guinea has one serious drawback: it has no primates, except for humans. Thus, I come to this conference on primate conservation as an underprivileged and emotionally deprived observer, rather than as an involved participant. Nevertheless, it is easy for anyone to become interested in primate conserva tion. The public cares about primates. More specifically, to state things more realistically, many people care some of the time about some primates. Primates are rivaled only by birds, pandas, and the big cats in their public appeal. For some other groups of animals, the best we can say is that few people care about them, infrequently. For most groups of animals, no one cares about them, ever.

Pesticides in ground, surface and drinking water are a hot topic under continuing discussion. This complete and authoritative volume draws together information on all key issues on the fate and behaviour of pesticides in water systems. The scope of the practice-oriented contributions and the eminence of contributing authors make it an important source for researchers and practitioners in the plant protection and crop science field.

"Reviews of Environmental Contamination and Toxicology" contains timely review articles concerned with all aspects of chemical contaminants (including pesticides) in the total environment, including toxicological considerations and consequences. It attempts to provide concise, critical reviews of advances, philosophy, and significant areas of accomplished or needed endeavor in the total field of residues of these and other foreign chemicals in any segment of the environment, as well as toxicological implications.

Volume 9 in this series consists of four chapters on vectors that affect human or animal health and six chapters on plant pathogens and their vectors. In Chapter 1, Alex S. Raikhel discusses vitellogenesis in mosquitoes: the cornerstone of the reproductive cycle involving massive production of yolk precursors by the fat body and their accumulation in developing oocytes. In anautogeneous mosquitoes, vitellogenesis is dependent on the availability of a blood meal and, as a consequence, is linked to transmission of pathogens. Therefore, elucidation of mechanisms governing the mosquito vitellogenesis is critical for the successful development of novel strategies in vector and disease management. Previous reviews on mosquito vitellogenesis have dealt predominantly with hormonal control. The goal of this review, however, is to summarize significant progress which has been achieved in understanding mosquito vitellogenesis at the cellular, biochemical and molecular levels. It is with these disciplines that we expect to fully understand the mechanisms governing this key process in mosquito reproduction.

Insects as a group occupy a middle ground in the biosphere between bac at one extreme, amphibians and mammals at the other. teria and viruses of insects present special problems to the The size and general nature study of entomology. For example, many commercially available instru ments are geared to measure in grams, while the forces commonly en countered in studying insects are in the milligram range. Therefore, tech niques developed in the study of insects or in those fields concerned with the control of insect pests are often unique. Methods for measuring things are common to all sciences. Advances sometimes depend more on how something was done than on what was measured; indeed a given field often progresses from one technique to another as new methods are discovered, developed, and modified. Just ofthese techniques find their way into the classroom when as often, some the problems involved have been sufficiently ironed out to permit students to master the manipulations in a few laboratory periods. Many specialized techniques are confined to one specific research lab oratory. Although methods may be considered commonplace where they are used, in another context even the simplest procedures may save con siderable time. It is the purpose of this series (1) to report new devel opments in methodology, (2) to reveal sources of groups who have dealt with and solved particular entomological problems, and (3) to describe experiments which may be applicable for use in biology laboratory courses."

In continuation of Somaclonal Variation and Crop Improvement I (1990), this volume is comprised of twenty-four chapters dealing with somaclonal variants showing resistance to salt drought, herbicides, viruses, "Alternaria," "Fusarium," "Glomerella," "Verticillium," "Phytophthora," fall armyworm, etc. in a number of plants of economic importance.
It is divided into two sections:
Section I. Somaclonal Variation in Agricultural Crops: wheat, rice, maize, sorghum, potato, tomato, "Lotus," "Stylosanthes," banana, strawberry, citrus, colt cherry.
Section II. Somaclonal Variation in Medicinal and Aromatic Plants: "Atropa," "Carthamus," "Hypericum," "Lavatera," "Nicotiana," Primula, Rauwolfia, scilla, and Zinnia.