In recent years there has been a widespread revolution in both the practice and teaching of biology. New curricular reforms have appeared at both the secondary and college levels. To a large extent, the revolution in teaching reflects change at the forefronts of biological research. It is impossible, of course, to define something as complex as a scientific revolution in a brief space. Nevertheless, several characteristics of the "new biology" have become discernible. Perhaps the most apparent of these is the emergence of "molecular biology," the use of biochemical methods for understanding life phenomena. Older problems of genetics, embryology, evolution, cellular physiology, and even taxonomy, have been studied in a new light at the molecular level.

Behind molecular biology, however, lies a more fundamental characteristic of the revolution in life sciences. Biologists have begun to realize that many problems previously approached in a qualitative or descriptive manner can now more meaningfully be approached by analytical and experimental techniques. The mere use of experiments, of course, is not new to biology. Since the seventeenth century, experiments have played a large role in answering many questions about animal and plant functions. In recent years, however, growth in biochemical knowledge and technique has made it possible to apply experimental analyses to questions previously approached only by descriptive methods. It has been principally by asking questions in molecular or biochemical terms that applications of experimental techniques to biological phenomena have been broadened.

Few biologists would deny that these changes in their discipline are for the better. Yet, there is one aspect of this biological revolution which seems to have received less than its due share of attention. Especially on the introductory level of instruction, the inclusion of new information has often taken precedence over an analysis of the reasoning through which this new information was obtained. It is laudable to include within an introductory textbook the experiment by which a certain bit of biological knowledge was gained, as well as that bit of knowledge itself. Yet, we often find that a student can read a detailed description of an experiment without fully comprehending the hypothesis that the experiment purports to be testing . . . or, at times, even what the hypothesis is.

To correct this deficiency is the primary aim of the present book, prepared in response to many requests following the publication in the spring of 1967 of the full-length text, The Study of Biology. Preserving the same approach as that used in The Study of Biology, the short version is particularly suitable for half- or quarter-year courses. The authors have attempted to focus on the most fundamental principles of biology without resorting to sweeping generalizations which lack supporting evidence. In concentrating on biological principles, the short version, like its parent text, treats equally both plants and animals. For the most part, however, the principles discussed here apply to almost all types of organisms. In brief, this book is designed to meet the demand of already existing short courses, as well as new courses of this type that are still under consideration.

Those who wish to gain some insight into the philosophy underlying the present book will find that a quick reading of Chapter 3 provides the best introduction. Like its parent book, The Study of Biology, this text is based on the authors' conviction that although there is no one scientifcc method, there is still an underlying pattern of deductive logic in every scientific experiment or observation. The text frequently stresses this pattern by an indented format, allowing a separation of an hypothesis from its prediction. To avoid monotony, however, the pattern of deductive thinking is as often emphasized within the regular text material itself. In either case, the aim is to aid the student in understanding just what predictions follow from the tentative acceptance of an hypothesis, and which of these predictions a particular experiment or observation attempts to verify or refute.

In concentrating on the deductive and experimental aspect of biological ideas, we have made liberal use of historical material. Wherever possible, we have tried to present the relevant information available to given investigators (to Mendel, for example, or to Bayliss and Starling) as they set out to solve a problem. Then, with knowledge of the experiments they designed-or the questions they asked-we have tried to show the various hypotheses developed and the deductive format implicit in the final result. The purpose of this emphasis is to reveal something of the pattern of logic involved in a wide variety of biological problems. In this way we hope that the student will develop a sense of how to critically analyze the results of scientific work.

Such an approach, however, has one difiiculty: a difiiculty still more pronounced in the preparation of a shortened text. Analysis of an experiment and the logic behind it requires considerably more space than simply listing results and stating any generalizations which might be drawn from these results. In order to keep this text to a length appropriate for most one-semester courses, it has been necessary to eliminate certain subjects which might otherwise have been included. For example, taxonomy and the evolution of plant and animal phyla have been omitted entirely. Similarly, we have not discussed at length human evolution or physiological functions of whole organisms. Instead, we have chosen to treat in greater depth a few general topics (such as the principles underlying evolution, or those underlying energy exchange in cells). In this way, we hope to provide a better preparation for students to handle meaningfully other biological materials which they may pursue beyond the bounds of an introductory course.

The instructor may wish to have a desk copy of the full text, The Study of Biology, as a source of lecture material to supplement the shortened version. For example, Chapters 21 and 22 of The Study of Biology (dealing with the evolution of plants and animals, respectively) will provide numerous examples to illustrate the general principles of evolution discussed in Chapter 13. Similarly, examples from Chapter 5 of The Study of Biology (dealing with the analysis and interpretation of data) can implement those areas where the experiments discussed in the shorter text call for data analysis and interpretation.

It is our hope that the instructor will impress upon the student the fact that the breaking down of an experiment into its deductive-logic format in no way recreates the thought processes that went into the original work. It is extremely doubtful that such a recreation can ever be brought about. One of the more unfortunate aspects of the "new" curricula in science is that the student has often been led to believe that he is actually being a research scientist as he carries out "inquiry-oriented" exercises. In reality, he is only discovering the pattern of logic that underlay the original investigation and which made it scientifically valid. It is easy, for example, to discover the deductive framework underlying Spemann's "organizer" experiments. When reading Spemann's description of his thoughts at the time, however, one has the strong suspicion that not even he knew the precise path of reasoning that led him to the answer.

A word is in order concerning the dichotomy between "content" and "process" - terms frequently posed in discussions of biology curricula. We believe that this distinction is an artificial one-that without scientific content, a study of scientific process becomes meaningless. In the present book, we hope to make the point that scientific statements are not sacred. To grasp this idea, so contrary to the public image of science, the student must understand what statements biologists make about the world (the "content") as well as how these atatements are supported through research (the "process").

Because our major efforts have been directed toward emphasis of important principles and ideas, scientific terminology has been reduced to a minimum; where needed, however, it is introduced. The same is true of primarily descriptive material (such as the phases of mitosis or cell anatomy). There is little reason to attempt to convert such material into experimental exercises; historically they did not develop that way. Further, despite its current disfavor, descriptive biology has been and still is an important part of the diacipline.

Finally, for the benefit not only of science majors but also of those students who will take no further science courses, we have attempted to make clear the meaning of scientific "truth," the limitations of science, and the importance of pure or basic research. Even the most intelligent layman cannot hope to be thoroughly familiar with even a small part of scientific research. He can, however, gain a general understanding of the nature of all science and thereby hopefully make more intelligent decisions concerning its many political and sociological ramifications.

Washington, D.C. J.J.W.B.
St. Louis, Missouri G.E.A. November 1967