BIOLOGICAL SCIENCE CAN AND SHOULD BE one of the most stimulating subjects a college student encounters. Nothing else, after all, has such immediate personal relevance as the phenomenon of life; and biological science, as the study of life, sheds light on what every individual experiences in himself and observes around him. Given the inherent excitement of the subject, there is no excuse for an introductory biology course to be dull. If large numbers of students in the past found biology a disappointing subject, one seemingly beset with long lists of names and cut-and-dried "facts" to memorize, then the blame must rest with those of us who were their teachers rather than with the students themselves.

Fortunately, the last decade has witnessed a nationwide effort to reorganize and redesign our approach to the teaching of elementary biology. The results of the Biological Sciences Curriculum Study and other projects to improve high school science courses are being increasingly felt by the colleges. Each year the entering students are better prepared than the ones the year before. This, together with the recent rapid pace of biological discovery, has led to an extraordinary growth of interest on the part of students. Many intend to enter some branch of biological science as their life's work; many others, who intend to pursue a career in some other field, nevertheless rightly see that in our day no liberal education is complete if it has not included biological science.

A textbook for today's better-prepared students must do justice to the newer areas of biological science without neglecting the older areas that provide the foundation upon which the new rests. Attempting an accurate and honest picture of the current state of our knowledge ( and ignorance ) in each of the major areas, without prejudice to any one of them, I have given extensive treatment to such topics as cellular ultrastructure, the mechanism of photosynthesis, molecular genetics, and developmental biology, but not at the expense of "whole organism" and population biology.

This book does not follow the once-traditional phylum-by-phylum organization; nor does it put plant and animal biology in separate sections, as is commonly done. Instead, it discusses the basic problems faced by all forms of life, whether plant, animal, or microbe ( I have tried hard to avoid slighting the plants, a tendency to which integrated texts are prone), and compares, in the light of modern evolutionary theory, the various alternative "solutions" to these problems seen in a variety of organisms. In this way, students are constantly reminded of the unity in diversity that characterizes life.

There is much disagreement among teachers about the sequence in which the various topics in an introductory biological science course should be taught. The disagreement is a legitimate one, since a good case can be made for each of several sequences. The plain fact is that each topic can best be understood if all the other topics have preceded it. This being impossible, every teacher must choose the sequence that best suits his conceptual approach to the subject. Thus, although strong arguments can be given for placing the discussions of cell division, genetics, and development with the other cellular topics at the beginning of the sequence, I have deferred them until later ( Part III ) for two reasons: First, I feel that study of genetics benefits more from prior knowledge of anatomical and physiological characteristics than study of anatomy and physiology benefit from prior knowledge of genetics. Second, since evolutionary theory rests upon genetics, there is considerable advantage in having the chapters on these two subjects close together. Those who find these justifications unconvincing can easily move Part III forward and follow the sequence I, III, II, IV, V. The treatment is flexible enough so that diverse sequences of chapters can be followed.

It is a particularly difficult decision whether to cover the major groups of organisms near the beginning of a textbook, so that students will be familiar with them when they are mentioned in other chapters, or whether to leave them until the end of the course, when students may approach their examination with more insight. I have followed the latter alternative here ( although the major groups are briefly introduced in Chapter 3 ) for the sake of a more meaningful discussion of evolutionary patterns in the plant and animal kingdoms.

This book goes deeper into many topics than has been customary in the past in introductory biology courses. Whenever possible, it includes discussions of important experiments and investigations, even though this takes much more space than a simple recitation of "facts"; the investment will be justifled if the student gets a feel for the way new information is obtained.

It is my conviction that it is useless merely to mention a topic for the sake of "completeness" of coverage, that if it is mentioned at all it should be given sufficient depth of treatment to make it meaningful. My experience in teaching the introductory biology course at Cornell (one taken by both science majors and students of the humanities) has shown me that it is often more difficult for a student to understand an oversimplified "elementary" presentation than one that is rigorous enough to engender some insight into the relevance of the material. For example, it was a frustration to me for several years that too many of my students seemed to find genetics a hurdle they could not master. I finally tried extending my treatment of the subject considerably beyond that given in most elementary biology textbooks; the result was that most of the students who would formerly never have grasped the essentials of genetics now did so, and some of them even became especially enthusiastic about that part of the course.

Given the rate at which our knowledge is advancing, no biological science textbook can be fully up to date at the time a student reads it. It is important that the student understand this as one aspect of the dynamic, searching, inquiring nature of science. Hence I have not hesitated to warn repeatedly that more research is needed before some of the ideas discussed can be reliably evaluated, and I have added footnotes to draw attention to the fact that while the book was in press doubt was cast on some of the theories to which it gives major emphasis (e.g. the unit membrane theory). Often evidence is cited both for and against two or three opposing hypotheses, and it is made clear that a final decision is not yet possible. This approach, which encourages the student to evaluate the evidence for himself, can bring it home to him that much remains to be done and that the effort will be exciting.

Because no one book can give adequate coverage to all the diverse aspects of biological science, students should be encouraged to consult other sources. Lists of authoritative references and of readings accessible to the beginner will be found at the end of each chapter; guides to identification are listed at the end of Chapters 21 and 22. Many of the suggested readings are articles from Scientific American; the majoiity of these are available as numbered separates ( called offprints ).

A good index can be an important learning aid. Proceeding on what I believe to be the sound assumption that too many entries are better than too few, Ann M. Kingsbury has prepared an index through which the student can readily locate any topic, term, or proper name mentioned in the text.

In order to avoid encouraging students to memorize isolated and often sterile definitions, I have not included a glossary. Definitions of terms in context can be found through italicized page references in the index.

Many people read parts of this book in manuscript and offered valuable advice and criticism. I wish to acknowledge especially the aid of the following of my colleagues at Cornell University: David W. Bierhorst, A. W. Blackler, W. C. Dilger, Richard D. O'Brien, Richard B. Root, and H. T. Stinson. The criticisms of Peter H. Klopfer of Duke University and Lester Ingle of the University of Illinois were also most helpful.

My thanks are due to the many individuals, museums, and business firms that lent me photographs and permitted me to publish them; their names are given in the pertinent legends. I am particularly indebted to four of my colleagues who spent long hours preparing special photographs: Thomas Eisner, Herbert Israel, Edgar M. Raffensperger, and Verne N. Rockcastle.

It is a special pleasure to acknowledge the imaginative and tireless help of my illustrator, Paula DiSanto Bensadoun. Her drawings add immeasurably to the value of the book.

My thanks also to Ruth Thalheimer and Hugh O'Neill of W. W. Norton, who were responsible for the copy editing and the design.

Finally, I wish to express my gratitude to my wife for her endless patience and interest during the years of writing when I must have been a constant trial to my family.

W.T.K.
Ithaca, New York
October, 1966