Chapter III

Culturing Microbiology, 1930-1945

A. Introduction -- The Project to Reform Microbiology

On July 5, 1940, C.B. van Niel gave a lecture on the biological and philosophical implications of debates about spontaneous generation. Through the windows of the Jacques Loeb Laboratory, the nine students in his course "General Microbiology" could see cormorants, gulls, and pelicans, as the surf surged over irregular formations of granitic rock. In the laboratory, the rich malty aroma of yeast cultures mingled with the salt air, as graduate student Roger Stanier prepared demonstration materials.⁽¹⁾ In the afternoons and evenings, the students, including the physicist-qua-biologist Max Delbrück, conducted their own experiments as they endeavored to become microbiologists. Under van Niel's influence, they might come to believe that there was no higher purpose.

In the 1930's, van Niel endeavored to make microbiology into a grand theoretical project with ties to physics and biology, rather than to medicine and industry. To a considerable extent, he succeeded. By taking advantage of his intellectual, institutional, and social opportunities, van Niel cultivated microbiology as a fundamental science. In the 1930's, he won a significant number of converts to his conception of microbiology, including several students who went onto hold prestigious positions. He continued to conduct first-class research in bacterial photosynthesis, demonstrating the value of research on microorganisms. By the end of the 1930's, van Niel's project to reform microbiology was well underway.

In the 1930's, life in van Niel's laboratory very much realized the romantic idyll imagined by Sinclair Lewis in the novel Arrowsmith. Especially between 1936 and 1942, van Niel, his students, and colleagues experienced scientific research as a rarefied spiritual activity of committed brethren living apart from everyday life. As far as van Niel and his students were concerned, they were engaged in a noble quest for the comprehension of nature that served the cultivation of the mind and the advance of civilization.

Van Niel had great expectations for microbiology as for all science. His conception of science resembled the German ideals of Wissenschaft and Bildung.⁽²⁾ The belief underlying his project was that science was fundamentally a moral and cultural endeavor, not a practical and technical process. Van Niel sought to cultivate this view of science especially in the United States where it seemed to be lacking. He rejected utilitarian goals and counted only the pursuit of knowledge as the proper aim of science. Even beyond that, the ultimate purpose of science for van Niel was the cultivation of the mind. Only by achieving rationality could an individual become fully autonomous. The practice of science, van Niel believed, produced the free and rational individuals supposed to constitute the best society. His most explicit statements of this conception of science occur in lectures he gave in the 1940's and 1950's. The elements of these views, however, are present in his unpublished lectures and correspondence from this period.⁽³⁾ In this chapter, I use the phrase wissenschaftlich science to refer to van Niel's conception of science as a cultural and intellectual project aimed at the comprehension of nature and the cultivation of mind. For van Niel, the cultivation of microbiology as a general science of life was situated in the context of that larger ambition.

In the early 1930's, theoretical bacteriology or general microbiology could claim a handful of competent practitioners, but it was vastly overshadowed in institutional power and public prominence by medical bacteriology and industrial microbiology. Scientifically, van Niel sought to develop the ecological and physiological aspects of microbiology so that it could be integrated into general biological knowledge. Van Niel was not alone in this ambition. By the 1930's, an increasing interest in general microbiology was discernible. J. Howard Brown, the thirty-third president of the SAB wrote in 1932 that he viewed "with gratification" the "renaissance of the biological approach to bacteriology," though his own institutional home was the Department of Pathology and Bacteriology at Johns Hopkins University.⁽⁴⁾ Microbiologists especially sympathetic to the biological approach included Leo Rettger at Yale and Barnett Cohen at the Johns Hopkins School of Medicine. At the Scripps Oceanographic Institute, Clifford Zobell pursued marine microbiology. Some scientists whose research was predominantly medical or agricultural undertook investigations they and others considered to be fundamental microbiology. The soil microbiologist Selman Waksman, for example, carried out substantial research on the physiology and ecology of microorganisms in the 1920's and 1930's. Cornell and the state universities in Iowa, Minnesota, and Wisconsin also had strong programs in agricultural microbiology which accommodated research in bacterial physiology. Scientists at the Rockefeller Institute for Medical Research undertook research that addressed both practical medical problems and related fundamental questions. In Europe, Marjory Stephenson pursued research in bacterial physiology in connection with the F.G. Hopkins's program to develop biochemistry into a fundamental science. The Pasteur Institute provided an important location for fundamental research on microorganisms when it established the Service de Physiologie Microbienne in 1938 under the leadership of André Lwoff.⁽⁵⁾

Van Niel enjoyed nearly ideal institutional arrangements in which to cultivate microbiology and practice microbiology as a science of life. As a researcher at Stanford's marine station, he had no significant obligations to applied microbiology or to medical bacteriology. The Stanford medical bacteriologists were safely ensconced on the main campus sixty miles away in Palo Alto, and van Niel was under no pressure to interact with them. In contrast, at the Hopkins Marine Station (HMS), he was surrounded by researchers investigating general biological problems. Committed to developing experimental biology at Stanford, President Wilbur and his chief administrative ally the protozoologist C.V. Taylor supported the view that microbiology, along with botany, zoology, and physiology, was simply a part of biology. These circumstance encouraged van Niel to conceive of microbiology as a general science of life, without regard for medicine or practical applications. Unlike many researchers concerned with microorganisms in the 1930's, van Niel had motive, opportunity, and even obligation to practice microbiology as a general science of life. In his laboratory at the HMS, van Niel undertook the broad exploration of the microbial world, meaning the systematic study of the morphology, physiology, biochemistry, ecology, and evolutionary relationships of microorganisms.

The successful pursuit of van Niel's project depended on obtaining adequate patronage and demonstrating the value of his approach through research. Because van Niel's scientific interests were congruent with general trends in the life sciences, he could obtain patronage for his project and an audience for his message. His research conformed to the increasing reliance on chemistry and physics, an important trend in the life sciences in the 1930's. Throughout the 1930's, the Rockefeller Foundation (RF) provided research funds, orchestrated by Taylor, to Stanford's experimental biologists. Van Niel continued to be a central member of this group. Throughout the 1930's, photosynthesis in bacteria continued to be the focus of his research. This research, discussed in more detail below, illustrated the potential for microbiology to approach the great questions of biology. It addressed issues of great interest to both physicists and plant physiologists. Connecting the study of bacteria to physics through photosynthesis was a valuable step toward making microbiology into a wissenschaftlich science.

To make microbiology into a dynamic field, however, required more than impressive research. Students, colleagues, and even competitors were necessary. Though not an institution builder in the conventional sense, van Niel sought to expand the number of researchers who conceived of microbiology from a biological rather than medical viewpoint. In his public lectures and research seminars, he proselytized for the value of General Microbiology.⁽⁶⁾ Even more important, van Niel invented a social instrument for culturing microbiology and microbiologists, an intensive course in general microbiology. This course proved to be a highly effective means for propagating both his conception of microbiology and his ethos of science.

In sum, van Niel sought to transform microbiology into his conception of a pure science in which practice served theory, the concrete the abstract, and the diverse the unitary. His vision included a set of moral and aesthetic values about science and how it should be practiced. To that end, van Niel cultivated microorganisms, microbiology, and microbiologists.

B. The Course in "General Microbiology"

The intellectual, social, and cultural dimensions of van Niel's reformation project for microbiology converged in his teaching. Between 1930 and 1943, van Niel taught a course called "General Microbiology" every year except one. At one level, it was no more than a sincere attempt at teaching. Its purpose was simply to transmit as effectively as possible a set of techniques and a body of information. Secondly, teaching the course gave van Niel the opportunity and the obligation to define general microbiology, to articulate its conceptual structure, and to provide an account of its origins, controversies, and major advances. A third purpose of the course was missionary in spirit, to secure converts to his conception of general microbiology. In the 1930's, van Niel created microbiologists by teaching microbiology.

Neither entrepreneurial nor dictatorial, van Niel induced students and colleagues to study microbiology through a process more like romantic seduction than cunning salesmanship or cynical coercion. Passionate about his subject, van Niel presented microbiology as a great and imposing science with all the aesthetic and intellectual appeal of any major discipline, including physics. Usually given during the summer quarter, "General Microbiology" met for a full day three times per week, yielding about twenty-eight sessions.⁽⁷⁾ A ten week affair, the course was intense, demanding, and intimate. The classes were small in size with from six to ten students formally enrolled. Sometimes van Niel allowed a few auditors to attend the lectures.

Between 1930 and 1943, about eighty-five students and ten auditors attended van Niel's course. At least seven of these, including Robert Hungate, Michael Doudoroff, Steven Carson, Howard Bliss, Roger Stanier, Ed Anderson, and Dixie Lee Ray, became graduate students with van Niel. All of these went on to productive scientific careers and conducted at least a substantial part of their research within the frame of general microbiology. Hungate, Doudoroff, and Stanier trained their own students, many of whom also became general microbiologists. As described in more detail below, many postdoctoral fellows with van Niel were greatly influenced by the course in microbiology, including Horace Barker, a student in 1930, and J.O. Thomas, class of 1937. As we shall see, some of van Niel's students became "disciples" and embraced both his scientific and his philosophical views; some became "followers" and adopted only his scientific program; others became "dissenters;" they shared his cultural ideals but used what they learned to make microorganisms into tools to serve different research agendas.

As word spread of the uniqueness and high quality of van Niel's course, it began to attract established researchers. Photosynthesis researchers, especially, became an important constituency for the course. Robert Emerson, assistant professor of biophysics at Caltech, enrolled in the course in 1933. In 1934, C.S. French, another promising photosynthesis researcher, took the course, en route to a postdoctoral fellowship at Caltech.⁽⁸⁾ By 1940, the course was famous enough to attract elite researchers from a range of backgrounds. Notable participants included the physicist William Arnold in 1937, the Danish biochemist Hermann Kalckar in 1939, and the physicist Max Delbrück in the summer of 1940. Delbrück's participation is especially noteworthy and discussed in more detail below.

Talented graduate students with other faculty members provided another constituency for the course. Two examples are Robert McElroy, class of 1941, and A. Doermann, class of 1943. McElroy went on to a distinguished career in research in biology. Doermann, a student of Beadle, went on to work with Delbrück to develop the field of bacteriophage genetics.

Like other marine laboratories, the HMS metamorphosed in summertime from a quiet outpost into a lively center of activity when students, visitors, and lost tourists arrived at its doors. From the beginning, teaching was the main activity at the HMS in the summer. From 1918 until 1922, its bulletins announced: "The HMS fulfills a twofold function: first, it furnishes under exceptional natural advantages elementary and advanced instruction in biology; second, it provides facilities for research work." After 1922, perhaps at Wilbur's suggestion, research was listed first and teaching second.⁽⁹⁾ Despite the new emphasis on research at Stanford in the 1920's and 1930's, teaching undergraduate and graduate students remained a critical function of the HMS.

In 1929, Stanford students could choose from five laboratory courses or undertake independent research projects during the summer quarter at the HMS. The topics ranged from natural historical, taxonomic, and descriptive approaches to the new experimental biology. Traditional courses included "Marine Zoology," "The Algae," "Marine Invertebrates," and "Vertebrate Embryology." The experimentalists weighed in with "Physiology of the Cell," which promised to illustrate the properties and functions of living cells in quantitative terms, and independent research projects on the physico-chemical properties of protoplasm.⁽¹⁰⁾

Van Niel introduced his course in microbiology into this broad biological context. In the spring of 1930, he offered "General Microbiology" for the first time. It was listed as: "A laboratory course in which the student will become acquainted with the principal methods used in microbiological work. Representatives of most of the important groups of saprophytic micro-organisms will be studied, chiefly from the standpoint of their role in nature." It was unique among the courses that year in requiring two semesters of chemistry as a prerequisite.⁽¹¹⁾

The beginnings of the course were modest. In the spring of 1930, only one student enrolled, Robert Hungate, a Stanford graduate with no particular interest in microbiology. At Stanford, Hungate had studied a mixture of general biology, ecology, and botany. He decided to take van Niel's course on the recommendation of a friend working at the marine station. On April 2, van Niel presented the first lecture formally to his sole student. From then on, van Niel explained the basics of microbiology informally while Hungate took notes.⁽¹²⁾ (The content of the course is discussed in detail below.)

A rather unassuming person outside of the classroom, van Niel adopted a different persona as a teacher. In his teaching, he employed a powerful mixture of logos, pathos, and ethos. By all accounts, van Niel's lectures were mesmerizing. Students would sit for hours spell-bound by their intensity, clarity, beauty. Several students experienced dramatic conversions to microbiology.

Van Niel's impact on Hungate was immediate. "I was enthralled," wrote Hungate, "His lucid presentation of ideas, his keen memory and insight, coupled with an intense interest in microbiology and in the student made an indelible impression."⁽¹³⁾ Whereas Hungate had no prior inclination toward the subject, he chose a microbiological topic for a dissertation project. Hungate decided to investigate the protozoa and bacteria living in the guts of the termite in order to find out how these insects were able to digest wood. Earlier studies had shown that protozoa living symbiotically in the termite gut used the cellulose from wood as their carbon and energy source. Knowing that cellulose-decomposing bacteria are widespread in nature, van Niel suggested that bacteria might also play a role in the ecology of the termite. Hungate set out to investigate this possibility. Fallen Monterey pines in the neighboring woods provided ample research material.

Hungate went on to a successful career as a microbiologist. A valued friend and colleague of van Niel for five decades, Hungate held positions at the University of Texas; Washington State, Pullman; and the University of California, Davis, where he was Chairman of the Department of Microbiology from 1956 to 1962. Hungate later wrote that van Niel's influence was " the most profound...on my scientific career."⁽¹⁴⁾

Van Niel was willing to make substantial investments in students he considered to be promising potential allies. He secured a second important student the next time he offered the course. In the summer of 1930, Horace Barker, a Stanford student and friend of Hungate, signed on for van Niel's lectures. Barker had learned something about protozoans while working the previous year with Taylor. Barker was bold enough to ask van Niel for private instruction because a planned vacation in the Sierras prevented him from attending the regular course of lectures. Although surprised by the request, van Niel accepted the proposal, persuaded by Barker's apparent talent in science to give him private lectures. That summer, van Niel gave another second set of lectures to the regular class of four students.⁽¹⁵⁾

Like Hungate, Barker "quickly became convinced that microbiology was a most exciting subject." He found that van Niel "had a very impressive way of speaking," and that his "hypnotic intensity... made a deep impression."⁽¹⁶⁾ Especially intrigued by van Niel's discussions of the biochemistry of bacterial and yeast fermentations, Barker decided to pursue a Ph.D. in chemistry to prepare for future research on these subjects. In 1933, Barker returned to the marine station to work with van Niel for two years as an National Resource Council Fellow. That summer, Barker listened to van Niel's lectures on microbiology for the second time. He, too, went on to a distinguished career in research and remained a lifelong friend and colleague of van Niel.

Naturally, not all of the students who took van Niel's course were immediately captivated by the prospect of pursuing research in microbiology. Many had neither taste nor talent for it, and even some for whom van Niel had high hopes resisted its attractions. When a promising graduate of the class of 1932 left the marine station for medical school, van Niel felt compelled to admit the rejection to Kluyver.⁽¹⁷⁾ On balance, however, van Niel's record of success was impressive.

Participating in van Niel's course was a demanding experience. The first lecture of the day began early, at seven-thirty or eight o'clock in the morning, and could last as long as four hours. After a quick lunch, van Niel gave another lecture, again often four or five hours in length. Some afternoons were occupied with laboratory exercises. Not infrequently, students and teacher would work until midnight or one o'clock in the morning.⁽¹⁸⁾

Van Niel presented general microbiology as a sophisticated field of inquiry with a long and noble history and a powerful set of general principles. The course had two stated aims: to teach students how to work with microorganisms and how to think about microbiological problems. In van Niel's words, the course presented "methods and concepts." The first half of the course covered the basic methods of microbiology and introduced several conceptual points. The second half of the course surveyed the major groups of microorganisms and reviewed the biochemistry of their metabolic processes. Throughout, students were given intensive practice in the basic techniques of microbiology, how to use a microscope, how to identify microorganisms, how to prepare cultures, and how to conduct simple biochemical assays.

As van Niel intended, however, the course offered more than technical skills and substantive information. Throughout the course, van Niel used the teaching of practical methods to illustrate theoretical or philosophical points. He artfully integrated laboratory practice and conceptual discussions. Van Niel's exposition of principles of scientific reasoning were exceptionally clear and detailed. They articulated logical principles for scientific research. As one graduate wrote, "No participant would ever forget this course because in addition to scientific knowledge, it imparted a philosophy and a method of thinking about the approach to biological research."⁽¹⁹⁾ For van Niel, science was a means for cultivating the qualities most necessary for becoming a rational, autonomous individual. This philosophy influenced the design and content of his course. Reflecting his deeper purpose, it was carefully crafted to allow a gradual increase in conceptual understanding and in technical competence. Overall, the course was designed to serve van Niel's general project to make the practical and concrete serve the theoretical and the abstract.

Van Niel established the basic structure of the course in the 1930's and never changed it. The contents necessarily expanded over the three decades it was given, but gradually. Van Niel carefully incorporated new information into the structure of his course in such a way that it did not appear to be "revolutionary." The progress of microbiology appeared to consist in the steady accumulation of facts in concert with the revision of theory and hypothesis as facts and observation demanded. Because van Niel integrated current research systematically, the course served as a valuable resource for researchers at the cutting edge of biochemistry, physiology, and microbiology.

In the first five sessions, van Niel addressed a mixture of practical and philosophical issues. He told his students that they were engaged in a search for truth, the aim of which was to obtain a unified picture of the world. He asserted that a philosophy of life could be derived from this search for truth. He conveyed a set of moral values about the practice of science, along with lessons in basic technical procedures, and he provided a set of general principles in which they could consider their work. In the second half of the course, van Niel gave general reviews of the morphology, classification, and biochemistry of selected groups of microorganisms. In addition to its practical and theoretical component, van Niel's course conveyed a great deal of substantive information in a straightforward and clear manner. Van Niel's approach integrated biochemical analysis with an ecological perspective. By the end of the ten week course, students had considerable experience with basic microbiological techniques. They had learned how to handle a wide range of bacteria and yeasts and they had been given a thorough grounding in the biochemistry of microbial metabolism.

Van Niel's course provided a striking alternative to what would be taught in a course in medical bacteriology. An influential textbook of medical bacteriology of the era provides a basis for comparison. Topley and Wilson's, as it was familiarly called, was the standard British compendium of medical bacteriology in the 1930's and 1940's.⁽²⁰⁾ In this textbook, the topic of "the biological characteristics of bacteria" was awarded 64 out of 950 pages of the first volume and none in the 1000 pages in the second volume. Bacterial classification was given 15 pages. Bacterial variation, a topic important to medicine, received 22 pages. Other points of overlap with van Niel's course were discussion of pure cultures and sterile technique. In Topley and Wilson's, there was no discussion of enrichment cultures, evolution, ecology, or general biochemical principles, all essential elements in van Niel's concept of general microbiology. Topley and Wilson's provided a detailed review of all that was known about the bacteria and viruses pathogenic to human beings and domesticated animals. Its purpose was to provide information necessary to diagnose, treat, or prevent infectious disease. The technical methods covered in Topley and Wilson's were necessarily a part of van Niel's course. Most of the techniques van Niel taught in his course were standard components for any training in bacteriology. Anyone working with microorganisms needed to know how to use microscopes, Petri dishes, pipettes, and culture flasks. The aim and outlook of medical bacteriology, however, were distinctly different from those of the microbiology presented by van Niel.

In the first lecture, van Niel introduced his subject by offering two justifications for studying microbiology. Van Niel pointed out that because we inevitably come in contact with microorganisms, we inevitably learn something about them. The second reason was more compelling. Van Niel expressed his belief that microbiology could make unique contributions to biology. As he wrote in 1932:

It would seem that a number of problems dealing with general biology could be advantageously attacked by a study of less highly developed living beings...By studying the simpler representatives among the living beings one may arrive at conclusions which can be applied also to the higher types...A study of those simpler living beings also tends to reveal the fundamental features of life; rather than stressing the differences and complexities, it leads to a conception of the basic phenomena.⁽²¹⁾ Thus, a crucial point for van Niel was that microorganisms revealed "fundamental" aspects of life because they were "simpler." A principle message of the course was that microbiology was an integral part of biology, and biology an integral part of "Science," to use van Niel's term. He emphasized that bacteria and other microorganisms were not the evil enemies of man as they might be construed in a medical context, but legitimate beings in nature with the potential to yield unique insights for biology.

Van Niel defined the possible subject matter of microbiology in the broadest possible terms. "What constitutes microbiol?" he asked. "Things small enough so that we need microscopes to study them," was the answer. But van Niel was quick to point out that this characterization implied that microbiology could consider "Anything of cellular dimension." By this definition, much of biology could be subsumed by microbiology. He agreed, however, that many organisms live as single cells, and these he considered to be the material "par excellence" for microbiology. At the same time, he said it was "foolish to restrict [microbiology] in any such way." The scientific purpose of microbiology, van Niel said, was to develop methodologies that would lead to understanding the morphology, physiology, biochemistry, and classification of microorganisms.⁽²²⁾ As students learned in the first lecture in van Niel's course, there was no easy answer to the question, "What is microbiology?" It took ten weeks of intensive study and laboratory work to discover what van Niel considered to be its basic dimensions.

For each topic, he discussed the relationship between the facts and concepts of microbiology. Valid concepts, he said, were "all founded on observed facts," and "tried to integrate these facts." Concepts without facts were meaningless, and facts without concepts remained incomprehensible. Van Niel chose to treat his subject matter historically because, he told his students, this was "the best (and even only) way to appreciate the fundamental reasons for the main concepts."

In keeping with his theoretical approach to microbiology, van Niel emphasized that science was defined by its mode of practice, rather than in its results. Science was, he said, "an outlook, a process of thought, not compartmentalized, but one which takes into account knowledge, i.e. facts and hypotheses from other disciplines...."

From van Niel's point of view, research from different angles and on different levels of analysis contributed to a shared goal, a unified body of knowledge. Each discipline was dependent on the others for information and insights. Research in microbiology, properly understood, contributed to an ultimate if distant goal, the unification of science. Microbiology offered the potential for unifying biological, physical, and chemical knowledge.

Van Niel presented "unity" as a core ideal in science, including microbiology. He continued to emphasize the importance of "integration." Van Niel regretted that specialization, which he called "suffocating," had afflicted microbiology, as it had other sciences. As the science developed, he complained, "Some one person learned more and more about one small group of organisms, about one small organism, or about part of an org." Despite those tendencies, van Niel was happy to say that some scientists have "struggled to bring back a feeling of unity" in scientific thought. Ultimately, he believed, science would achieve a unified picture. Microbiology had unique contributions to make to this unified picture, he told his students. A purpose of his course, he said, was to illustrate the extent to which unity and integration in science had been achieved. For van Niel, the achievement of a unified picture through integration was the means to intellectual liberation from the incomprehensibility of scattered facts.

The purpose of science was not merely to accumulate facts and hypotheses, his lecture notes read, but "to arrive at a philosophy of life which has its firm foundation in reproducible observation, i.e. experiment." "Let us always keep in mind that Science is A Search for truth and understanding," he continued (capitals in the original). At the same time, he would emphasize that scientific truth was provisional, that it was "reached and accomplished only gradually and slowly, and that we are everywhere, a long, long way from any finality." He cautioned his students from accepting the statements of authorities or even their own past experience as constituting "the Truth."⁽²³⁾

In the first laboratory section, students examined water that contained kernels of pepper. The exercise was meant to allow students to repeat van Leeuwenhoek's discoveries of the seventeenth century. In the process, they learned how use the microscope. They also examined cultures prepared from commercial cakes of yeast, determined the number of cells per unit volume in a culture by counting cells with a hemacytometer, and learned how to grow yeasts on gelatin plates and in liquid cultures.

The second topic van Niel introduced was "the problem of spontaneous generation." The discussion included both a moral lesson and a philosophical point. The discovery of microorganisms, he pointed out, immediately raised questions about their nature and origin. "The problem, biologically and philosophically, is one of the most important," he told his class. He then gave a historical review of debates about spontaneous generation from the sixteenth through the nineteenth centuries. In the process, he asked his students to try to understand the logic of positions which could look foolish in retrospect. In his words, "Let us try to be tolerant, and that is best achieved by trying to understand." The history of this debate, he said, illustrated that scientific truth was provisional. All that could be concluded in 1942, he said, was that while there was "No expt'l demonstration of spont. gen." neither was there any conclusive answer to the question "How did life get a start?"

In the laboratory section linked to this topic, van Niel introduced his students to the basic methods essential for working with microorganisms. He explained how some of the debates on spontaneous generation had arisen because of differences in techniques used. Most importantly, he demonstrated "sterile technique." Students learned how to sterilize media and how to handle cultures so that unwanted microorganisms were rigorously excluded.

The third topic, which built from the second, also combined practical and theoretical components. It concerned the methods and techniques of preparing and maintaining "pure cultures," which van Niel emphasized were crucially important for experimental work.

Van Niel linked these practical techniques to a theoretical discussion. The title for his fourth topic was, "The Causality Principle in Microbiology: Koch's Postulates." First articulated in the 1880's, "Koch's Postulates" referred to a set of criteria by which a causal relationship between a specific microorganism and a specific disease could be conclusively determined. Van Niel explained how these postulates could apply to determining the relationships between a specific microorganism and a fermentation processes. Van Niel then extended the discussion of Koch's Postulates into an examination of the nature of experimentation and the general issue of "causality" in science.

Van Niel emphasized that "causality" was a fundamental problem in experimental science. The general problem was to determine between two simultaneous events which was cause and which effect. He described debates in the nineteenth century about the nature of fermentation and putrefaction to illustrate the problem. Van Niel gave Koch credit for making the clearest statements on how to conclude logically that microorganisms were causative agents of various phenomena:

The fact that Koch's studies were concerned with disease have here and there led to the belief that the postulates are of importance only in that connection. However, they are of a far deeper and more general significance, and should be considered as one of the most salient of our methodological apparel [sic] wherever the problem of causality is concerned. Koch's postulates were the only contribution from medical bacteriology van Niel admitted into his course. He described the postulates in relation to determining the cause of disease: First, a specific microbe would have to present in an animal or person with a specific disease. Second, the microbe would have to be prepared in pure culture. Third, "inoculation of a healthy individual with the pure culture should lead to the appearance of the disease." And, fourth, it should be possible to isolate the specific microbe from the newly diseased individual. Van Niel emphasized that the first three should be rigorously tested before claims of causality were made.

Once his students had learned a few basic techniques, van Niel introduced "experiment" as a concept. "Experimentation," he said, "has a very definite aim. It means to set up conditions, carefully and knowingly, reproducible and unambiguously, which will allow of a definitive answer, yes or no, to a simple question." He emphasized that "the way of putting the question is of paramount importance for an interpretation of experimental results." He advised his students to think carefully before launching into experimental work. Van Niel used the question "How does a yeast cell grow?" to illustrate how scientific analysis should work. Careful observation of the process was a necessary starting point. However, to describe the process and call it "budding" was "by no means a final answer in its...scientific sense to the question." He suggested ways to break down the process into problems that could be approached by experiment: "By experimentation, we may be able to ascertain that prior to bulging a local change in the rigidity of the cell wall occurs." He then continued to illustrate how each question could be broken into subsidiary ones. "Proceeding in this manner," he continued:

...we shall come to a point where, by drawing on the existing knowledge in mechanics, mathematics, physics, chemistry, and biology, a picture is achieved which will tell us how a yeast cell multiplies, so that we can understand (or integrate) many interlocking details of the simple, (at first sight), question posed. Van Niel's discussion reveals that he believed that scientific progress occurred gradually and required the integration of many observations and theories from many points of view. "An ever more detailed study permits us to draw more and more experiences from other fields into our present one. So that the advance of knowledge is a gradual one; it approaches closer and closer and in doing so implies an ever increasing inclusion of knowledge from other fields."

Van Niel also discussed the limits of experimental science by raising the question "Why does yeast cell multiply?" This question, he said, could not be solved scientifically. "This implies that we must be aware of the fact that our experimental science has its limits -- and that those begin where the philosophical problem of purpose start." He also pointed out that the availability of methods and techniques restricted the range of questions open to "experimental attack."

In the fifth session, van Niel introduced the topic to which he was most indebted to his training at the Laboratory for Microbiology in Delft, the theory and practice of "enrichment cultures." This term referred to a very simple process, changing the ratio of organisms in a culture by manipulating the chemical or physical properties of the growth conditions. This simple process could potentially produce valuable effects. Van Niel told his students that the technique had been developed and most skillfully used by his two "heroes" in microbiology, Winogradsky and Beijerinck. It was now, he said, "an integral part of our science."

The enrichment culture technique was extremely important to van Niel because it allowed the microbiologist to accomplish three distinct tasks. First, enrichment cultures were a means for bringing microorganisms from nature into the laboratory. For microorganisms whose physiologies are understood, he noted, representatives could be isolated at will from almost any environment. Enrichment cultures were more powerful than that, if used skillfully. For any specific physiological problem, van Niel said, it would be possible to isolate organisms ideal for studying it, provided the problem was defined specifically enough. For example, if one wanted to study the physiology of tolerance to highly saline environments, it was quite easy to obtain a culture of a microorganism with that characteristic. Third, he claimed that this procedure offered an experimental approach to the problem of ecology. He argued that this procedure could be understood as an experimental demonstration of Darwinian natural selection.

For second half of the course, van Niel surveyed the morphology, biochemistry, and physiology of major groups of non-pathogenic microorganisms. He began with the yeasts and then covered the major groups of non-pathogenic bacteria, the lactic acid bacteria, the acetic acid bacteria, the propionic acid bacteria, and the Coli-aerogenes group, or Enterobacter. For each group, he discussed their morphology, modes of reproduction, classification, and the biochemistry of their metabolism.

Despite its emphasis on microorganisms in nature, the course had obvious connections to applied microbiology and medical bacteriology. Many of the bacteria and yeasts considered in the course had first come into human hands through the making of beer, wine, and dairy products.⁽²⁴⁾ Their practical relevance was the main reason they had been studied in the first place. Van Niel included discussion of their practical worth, but emphasized that general principles of biochemistry and physiology were more important.

Van Niel began his discussion of yeasts with the problem of defining the group biologically. He discussed in detail the various kinds of yeasts, their modes of reproduction and their classification. He then gave an account of the biochemistry of their metabolism and a history of nineteenth century debates on the nature of fermentation. He presented Pasteur as the most important defender of the biological theory of fermentation. He emphasized that speculative chemistry in the nineteenth century had yielded many ingenious theories, many of which were disproved by experimental analysis. Alcoholic fermentation provided a case in point. He explained that the German chemist Neuberg had shown through experiment that the synthesis of alcohol by yeast could be understood as the end result of a series of simple steps, most of which consisted of transfers of hydrogen atoms. This interpretation fit most closely with the theory proposed by Kluyver in 1924 concerning the unity of biochemistry.

Van Niel discussed the acetic bacteria acid in historical terms as well. He described how these bacteria were capable of converting ethanol into acetic acid, which made them exceptionally unwelcome to vintners. He used a discussion of the metabolism of the acetic acid bacteria to illustrate general mechanisms of oxidative metabolism. This lecture topic provided an occasion to describe the debate between Wieland and Warburg over the nature of biological oxidations.

When discussing the propionic bacteria, van Niel was forced to admit practical applications into his lectures. He discussed the role of propionic bacteria in the making of various kinds of cheeses, which his own dissertation work had investigated. He went on to discuss their biochemistry and taxonomy in a broad biological context as well.

At some point in the course, van Niel would discuss the problems of constancy and variability in microorganisms. As always, he took an even-handed approach to controversy. He attempted to lay out the merits of both sides while subjecting both to logical criticism. As always, he cautioned his students against ridiculing positions they did not fully understand. The pleomorphists believed that bacteria were almost infinitely variable. According to their critics, the pleomorphists often worked with cultures that contained more than one species of bacteria. They sometimes interpreted different kinds of organisms as different stages of a life-cycle of one species. Van Niel judged the pleomorphist position to be "wanting in accuracy." At the same time, he pointed out that the triumph of the monomorphist position resulted in an overly rigid view of bacteria that had inhibited recognition of their physiological flexibility. Van Niel recognized this phenomenon as an important research topic. He described how important it was to determine whether an adaptive change in a culture of bacteria was a temporary response to the environment or the result of a heritable mutation. Van Niel's students were introduced to both the oldest and the newest research on the subject, as he construed it.⁽²⁵⁾

Van Niel generally saved his favorite subjects, photosynthesis and chemosynthesis, for last. Again, he traced the history of research on these subjects in great detail. He gave his own work on photosynthesis a relatively modest place. After introducing the basics, van Niel developed the discussion of photosynthesis and chemosynthesis into an analysis of the general problem of energy transfer in biological systems.

Overall, van Niel's course gave a broad survey of the major groups of non-pathogenic bacteria and yeasts, a thorough review of their transformations of energy and matter, and an incisive statement of general biological or biochemical principles that could be derived from this knowledge.

Van Niel's course was an exceptionally useful means for presenting microbiology as a general science of life. It harmonized with his scientific and cultural missions, his personal philosophy, and his institutional setting. The course proved to be a highly effective means for securing students, defining microbiology, and promoting the use of microorganisms. It gave him the opportunity to articulate the theoretical and philosophical dimensions of microbiology and an audience to hear his conclusions. Van Niel presented microbiology as a part of a grand intellectual project to obtain a unified picture of nature. At the same time, he gave his students the practical and conceptual tools for taking part in that project. Learning these tools transformed many of his students into general microbiologists.

C. More Photosynthesis and Return to Europe

The summer course was only one instrument in van Niel's project to reform microbiology. His research on photosynthesis in bacteria was a second valuable means for demonstrating that microbiology could be practiced as a fundamental science. He continued research on this topic throughout the 1930's. Photosynthesis in bacteria proved to be an extremely valuable "object" because it was multi-faceted in its scientific appeal.⁽²⁶⁾ As a biophysical process upon which all of life depended, photosynthesis intersected physical, chemical, and biological problems. It was a central issue for both plant physiologists and biophysicists in the 1930's. Because it involved the interaction of light and matter, photosynthesis raised questions that required analysis in physical terms. Some could be answered only in terms of quantum physics, for example, the determination quantum efficiency. Understanding bacterial photosynthesis had implications for the origin of life, the evolution of plants, bacterial physiology, intermediary metabolism, and the quantum physics of the absorption of light energy. Van Niel's research on bacterial photosynthesis connected microbiology to these important fields.

Van Niel did not, however, seek or believe possible a "reduction" of biology to chemistry and physics. Rather, he saw the levels of analysis addressed by different disciplines as equally important. Each made essential and unique contributions toward producing a coherent body of knowledge. For van Niel, biology and physics were equal partners, along with chemistry and other disciplines engaged in a shared quest for a unified body of knowledge about nature.

Throughout the 1930's, biologists and physicists collaborated in the field of photosynthesis. Several historical accounts propose that a prominent role for physicists in biology was a new and distinctive feature linked to the emergence of molecular biology after the Second World War.⁽²⁷⁾ In contrast, this study and the work of historian Doris Zallen demonstrate that physics and research in photosynthesis went hand and hand in the 1920's and 1930's.⁽²⁸⁾

Van Niel took advantage of the attention attracted by his general equation for photosynthesis. He established and maintained contact with important researchers representing the gamut of interests in photosynthesis from plant physiology to quantum physics. Leading photosynthesis researchers began to visit van Niel's laboratory on a regular basis. In 1934, Robert Emerson, who had taken the microbiology course in 1933, returned to spend the summer with van Niel. At the time, Emerson was professor of biophysics at Caltech and already well-known for his innovative research on the biochemistry and biophysics of photosynthesis. After studying at Harvard, Emerson had gone to Warburg's laboratory for his doctorate. After his return to the United States, he collaborated with the physicist Arnold in a study that became a classic. Their ingenious experiments of 1932 analyzed oxygen evolution under intermittent rather than continuous light. This procedure allowed them to discriminate between light-dependent and light-independent reactions in photosynthesis.⁽²⁹⁾

Kenneth Thimann, an instructor in biochemistry at Caltech, worked under van Niel's direction in the summers of 1933 and 1934.⁽³⁰⁾ Trained in plant physiology, Thimann studied the chemistry of plant hormones. While at the HMS, Thimann collaborated with Barker. Though he did not enroll formally in van Niel's course, he later conducted research on microorganisms.

So many visitors came to van Niel's laboratory that Director Fisher began to complain to Wilbur. He appreciated van Niel's growing reputation, which reflected well on the station, but he became irritated by what seemed to be a constant diversion of resources to van Niel and colleagues. In 1934, Fisher complained to Wilbur that NRC fellows, most of whom came to work with van Niel, cost the HMS more money than they brought in. He called this "superparasitism" and asked the university to supply more funds.⁽³¹⁾ Wilbur, whose support for van Niel was unwavering, insisted that NRC fellows be welcomed, though he did not offer a concrete solution to the budget problems.⁽³²⁾ Fisher was willing to admit that Emerson provided very valuable assistance in setting up a "Warburg apparatus" for the HMS researchers.⁽³³⁾ This apparatus allowed the quantitative measurement of the volume of gases produced or consumed during photosynthesis or other physiological processes.⁽³⁴⁾

Nineteen thirty-five was an especially good year for van Niel and the project to reform microbiology. Newly endowed with the title "professor," van Niel looked forward to a sabbatical and to returning to Europe for the first time since his departure in 1928. He planned to spend a short time with Kluyver, and then make longer stays at the laboratories of Warburg in Berlin and Arthur Stoll in Basle. Van Niel told Kluyver he would rather stay in Delft, but that the RF, which was funding his trip, would not look favorably on that as he already had considerable experience there.⁽³⁵⁾ The year also witnessed the completion of the conversion of Barker. He "...has felt more and more attracted to pure (and applied) microbiology," van Niel wrote proudly to Kluyver in 1935.⁽³⁶⁾ They jointly arranged for the young chemist to complete his training in microbiology with Kluyver in Delft with the support of a General Education Board fellowship from the RF.

In 1935, photosynthesis was high on the agenda of experimental biology, nationally and internationally. That year, the Cold Spring Harbor Symposium on Quantitative Biology was devoted to the theme "photochemical reactions." An annual event, the meetings had been established in 1933 for the purpose of bringing together biologists, chemists, physicists, and mathematicians to open "the vast territory of quantitative biology."⁽³⁷⁾ Spread out over seven weeks, the symposium provided ample time for presentations, critical discussions, and informal interactions. It was an excellent opportunity for meeting new colleagues and displaying one's research accomplishments. In 1935, fourteen of the thirty-five papers concerned photosynthesis or closely related topics, such as the chemistry of chlorophyll or the absorption of radiation by the plant cell. Two weeks of symposium were devoted exclusively to photosynthesis.⁽³⁸⁾

Van Niel began his sabbatical year by attending this meeting. An invited speaker, van Niel took the opportunity to describe the significance of his research on bacterial photosynthesis and his general equation. He emphasized that his research offered convincing evidence that photosynthesis could be understood to be a typical oxidation-reduction reaction, in harmony with Kluyver's general theory of biochemistry. In this conception of photosynthesis, hydrogen was transferred from water, in the case of plants, or another compound in the case of bacteria, to carbon dioxide to make carbohydrates. This interpretation made obsolete schemes that proposed that the critical step in photosynthesis was the formation of a complex between chlorophyll and carbonic acid. The comparative biochemical approach, he emphasized, led to that insight. His research allowed him to argue that the study of bacteria was important for basic biological studies. He noted that the identification of the reaction intermediates in photosynthesis was still an unsolved problem. Van Niel suggested, "Now the purple bacteria seem to offer a much more favorable object for an experimental attack on this question than do the green plants."⁽³⁹⁾

While at the meeting, van Niel learned that another publication by Hans Gaffron, a student of Warburg in Berlin, challenged van Niel's interpretation of photosynthesis. Gaffron had begun studies on bacterial photosynthesis in the early 1930's independently of van Niel. Gaffron's work seemed to contradict the results reported in a recent dissertation by one of Kluyver's prized students. Van Niel turned this potentially inconvenient development into an opportunity for prolonging his stay in Delft and for promoting his theory against the views of Warburg.

Warburg's laboratory continued to be a leading European center for the study of photosynthesis. A lively group of biologists and physicists, including Delbrück, joined Gaffron occasionally for informal seminars on photosynthesis in the early 1930's. While Warburg's incisive research stimulated interest in photosynthesis, his domineering personality discouraged it. Delbrück, for example, later chose not to enter the field because of its contentiousness.⁽⁴⁰⁾ Warburg was much occupied with defending his determination of the quantum efficiency of photosynthesis. The controversy over this number, Warburg's stature, and the prestige of quantum physics stimulated interest in the biophysical aspects of photosynthesis to the disadvantage of the biochemical.⁽⁴¹⁾

Gaffron published experiments showing that the Athiorhodaceae, or "non-sulfur" purple bacteria could take up organic substances in the light. Like the purple sulfur bacteria studied by van Niel, these organisms were pigmented and dependent on light for energy. Unlike van Niel's purple bacteria, they consumed organic compounds rather than hydrogen sulfide as their main source of sustenance. Gaffron was unwilling to believe that these organic compounds were used by purple bacteria exclusively as hydrogen donors, like hydrogen sulfide or molecular hydrogen, as van Niel's general theory of photosynthesis demanded. Gaffron's position was based in part on logic and in part on prejudice. Logically, it did not seem plausible that the bacteria would break down organic compounds in order to extract hydrogen atoms that would then later be re-incorporated into organic compounds. More generally, Gaffron resisted the idea that hydrogen transfer reactions were the key to photosynthesis, much less all of metabolism, as Kluyver and van Niel proposed. Gaffron accepted Warburg's dogma that photosynthesis occurred via the photo decomposition of carbon dioxide, not water. "I was absolutely under the spell of Warburg," Gaffron later wrote.⁽⁴²⁾

The intellectual and political stakes were high. Intellectually, Gaffron's interpretation of his observations threatened van Niel's unitary concept of photosynthesis. Politically, controversy could be as valuable as accomplishment for winning attention. A controversy with Warburg was bound to be highly visible. Kluyver's student had taken a position in the East Indies and so could not defend his work directly. Van Niel did not hesitate to take the opportunity to resolve the matter. Van Niel's sponsor, the RF, agreed to his proposal to carry out experiments in Kluyver's laboratory at Delft.⁽⁴³⁾

After the CSH meeting, van Niel set sail for the Netherlands. Arriving in late August 1935, van Niel wasted no time in getting to Delft to see Kluyver and to start cultures of purple bacteria for his experiments. While these experiments were underway, Stoll wrote from Basle requesting that van Niel delay his arrival there because the laboratory was undergoing renovations. To van Niel's delight, this meant he could remain in Delft until January 1936.⁽⁴⁴⁾ This provided van Niel ample time to reinvestigate the uptake of hydrogen and organic compounds by the Thiorhodaceae in the light.

The extended stay in Delft gave Kluyver and van Niel time to collaborate on a major revision of bacterial taxonomy. In this work, Kluyver and van Niel criticized the available bacterial classification schemes, especially the system proposed in Bergey's Manual of Determinative Bacteriology, a publication sponsored by the SAB. Their principal objection was that systems of this nature were not guided by phylogenetic concepts. It was evident, they wrote, "that many of these systems are almost entirely the outcome of purely utilitarian motives." According to Kluyver and van Niel, these systems were of limited value because newly discovered facts often disrupted the entire scheme. They agreed that the "course of phylogeny will always remain unknown." Nonetheless, they proposed that a rational system based on phylogenetic reasoning, even if imperfect, was preferable to a purely practical one for two reasons. A phylogenetic system would more easily accommodate new findings. Further, constructing a system in this way would lead to new understanding of the natural relationships of bacteria. Kluyver and van Niel challenged the view that the morphology of bacteria was too simple to permit making phylogenetically meaningful comparisons. They argued that a judicious use of morphological features in combination with physiological characteristics allowed for meaningful attempts at rationally constructed phylogenies.⁽⁴⁵⁾

While working on this theoretical project with Kluyver, van Niel also carried out experiments to determine if organic compounds could serve as hydrogen donors for photosynthesis, as his general equation for photosynthesis predicted. After analyzing his results, van Niel concluded triumphantly that his theory held. He showed that both the Thiorhodaceae, the strain he had first studied, and the Athiorhodaceae, the organisms studied by Gaffron, carried out photosynthesis using organic compounds as hydrogen donors.⁽⁴⁶⁾ He looked forward to meeting Gaffron in Berlin to prove his point.

Early in 1936, van Niel traveled to Berlin to spend some time in Warburg's laboratory. There, he and Gaffron conducted experiments together in an effort to reconcile their differences. The debate was soon over; Gaffron conceded defeat.⁽⁴⁷⁾ Twenty-five years later, however, Gaffron was partially vindicated by Stanier and Doudoroff, van Niel's former students and good friends.⁽⁴⁸⁾ At the time, however, van Niel's unified concept of photosynthesis survived. Gaffron's interpretation was difficult to integrate into the general understanding of photosynthesis at the time, whereas van Niel's hypothesis was logical, beautiful, and led to experimentally testable predictions.⁽⁴⁹⁾

Van Niel did not see all that much of "de grote Otto," during his Berlin visit, but enjoyed a dinner at his house along with photosynthesis researcher Stacy French, then in Warburg's laboratory for a postdoctoral year.⁽⁵⁰⁾ At the end of the month, van Niel traveled to Stoll's institute in Basle.⁽⁵¹⁾ There, van Niel increased his familiarity with the chemistry of chlorophyll, but made no further headway on the reaction mechanism of photosynthesis. He was pleased to learn something about chlorophyll chemistry but decided not to pursue further research in that direction.⁽⁵²⁾

Meanwhile, Barker continued his experiments in Kluyver's laboratory in Delft. The time was profitably spent, literally and figuratively. At van Niel's suggestion, Barker undertook a systematic study of the methanogens, a group of bacteria that produce methane gas. In nature, these organisms account for the distinctive odor of swamps and bogs, where they live happily if oxygen remains in low concentrations. By launching the laboratory study of these organisms, Barker opened a large field of investigation that proved extremely important for microbiology.⁽⁵³⁾

In a related project, Barker found conditions under which bacteria using ethyl alcohol as a substrate could produce simultaneously acetic, butyric, and caproic acids along with methane. These processes were of commercial interest to the Delft Gist Fabrik (formerly the Gist-en-Spiritus Fabrik). The director of research and Barker reached an agreement under which Barker would be paid for his research if he agreed not to publish on the subject for three years.⁽⁵⁴⁾ Unlike van Niel in 1928, the more pragmatic Barker agreed to the arrangement. He was later able to buy a cabin near Mount Lassen, California, with his profits.⁽⁵⁵⁾

By the end of 1936, Barker and van Niel were both back in California. With van Niel's active support, Barker obtained a position as Soil Microbiologist at the University of California's Experiment Station, then on the Berkeley campus. Barker was extremely pleased by the position and found his new title and salary "impressive enough. The only disadvantage, Barker wrote to van Niel, was that he would not have time to "spend summer months playing at Pacific Grove." Reflecting a point of view he may have derived from van Niel, Barker wrote, "At present, I am trying to find out what 'soil microbiology' is....My conclusion so far is that the subject has much size but little shape."⁽⁵⁶⁾

As Barker began his new position at Berkeley, van Niel happily resumed life at the marine station. The great advantage of Barker's appointment was that it established the first foothold for van Niel's kind of microbiology on the Berkeley campus, albeit not in the Bacteriology Department, still a citadel of medical men. Still, Barker served as an important first link between van Niel's laboratory and the Berkeley campus. Joint seminars, collaborations, and exchanges were soon in place.⁽⁵⁷⁾

D. New Disciples and "The Spirit of 1936-42"

From 1936 until the entry of the United States into the Second World, van Niel achieved to a considerable extent the ambition to practice science as a spiritual quest for truth. During this period, van Niel continued to build his reputation as a theoretical or philosophical microbiologist. A talented and lively group of students and research fellows joined van Niel's laboratory where they had the opportunity to pursue scientific research as a morally and politically uncomplicated effort to comprehend nature. The remoteness of the HMS from urban life and international politics was an attraction for some. The opportunity to study photosynthesis with a recognized leader in the field was another. Graduate students Michael Doudoroff, Howard Bliss, Roger Stanier, and Steven Carson formed a tightly knit group in the late 1930's. Other graduate students with van Niel in this period were E.H. Anderson and J.O. Thomas. Visiting scientists who spent substantial amounts of time in van Niel's laboratory included W.A. Arnold, Hans Gaffron, J.W. Foster, and A.L. Cohen. Doudoroff, Stanier, and Bliss became lifelong friends and colleagues. Later, they looked back upon their experience with van Niel as a remarkable period in their lives when science was pure, simple, and fun. "The three years spent at Pacific Grove were among the happiest and most productive of my life," wrote Stanier.⁽⁵⁸⁾

Van Niel's laboratory became a vital center for research on a wide range of microbiological and biochemical topics, from photosynthesis to the decomposition of cellulose. An exceptionally talented student, Doudoroff adopted van Niel's program in general microbiology with unmitigated enthusiasm. Doudoroff graduated from Stanford in 1933 and received an M.A. degree in Zoology the next year. Working with van Niel, he undertook fundamental studies on bacterial physiology. His research on bacterial luminescence built on research first carried out by Beijerinck between 1889 and 1921.⁽⁵⁹⁾ Doudoroff also investigated the adaptation of bacteria to high salt growth media. He became equally famous in the laboratory for his wild parties and his incisive science, especially in biochemical analysis. He played a major part in the microbiology course, acting as teaching assistant in the spring and summer of 1937, and again in the summer of 1938. He became an important practitioner of general microbiology.

In 1938, van Niel secured another valuable convert to the project to reform microbiology. That year, Stanier, a graduate student in Bacteriology at the University of California, heard by chance of van Niel's course and decided to enroll. Stanier had not been impressed by medical bacteriology, despite the distinguished reputation of the Berkeley department and its head, Karl F. Meyer. Stanier was casting about for an environment more sympathetic to his intellectual ambitions. He found it at the HMS. His conversion to general microbiology was rapid, complete, and enduring. "My fate was decided in a few days," wrote Stanier. "It took less than a week to conclude that van Niel was the ideal master and teacher; general microbiology was to be my domain..."⁽⁶⁰⁾ The class of five students included Bliss, who also became a graduate student with van Niel. Because Stanier had already accepted a teaching fellowship at UCLA for following year, he was obliged to complete a Master's thesis there. As soon as he could, he returned to van Niel's laboratory to begin research for his Ph.D.⁽⁶¹⁾

Stanier was enthralled by van Niel's philosophical approach to science. He was the first of van Niel's graduate students to share his cultural interests and ambitions. Like van Niel, Stanier was deeply interested in philosophy, literature, and the arts. He had seriously considered becoming a historian before turning to science. Practicing science as cultural project appealed to Stanier. He readily took up the project of making microbiology into wissenschaftlich science.

Like van Niel, Stanier came to judge medical bacteriology as intellectually and culturally deficient. Most serious from their viewpoint was the fact that medical bacteriology focused almost exclusively on pathogenic organisms, which represented only a very small fraction of the microbial world. This narrow focus produced a distorted picture of the nature and activities of the microbial world. A second problem was that in medical bacteriological practice, organisms were often cultured in any growth medium that worked, rather than in a rationally established one. This practice caused confusion because the same organisms grown in different media sometimes behaved very differently, resulting in spurious claims of discovery of new species of bacteria. They saw this practice as a missed opportunity to obtain systematic information about bacterial physiology. In general, van Niel believed that the practice of medical bacteriology by its nature produced masses of random observations about microorganisms that were of limited use because they were not and could not be integrated into a coherent framework.

By his own account, Stanier "lazily" elected to work on the morphology and taxonomy of microorganisms because of his weakness in the physical sciences. Van Niel, however, did not judge his new student to be lazy. Rather, van Niel was delighted to tell Kluyver that Stanier was not only clever, but "mad" about his work, and showed an even more valuable and admirable quality: Stanier "loved the little beasts for themselves."⁽⁶²⁾

Stanier's dissertation research followed the basic approach that had been developed under Beijerinck and Kluyver in Delft and followed by van Niel in his dissertation. The difference was that at the HMS, there was no pressure to mention the potential practical applications of one's research. The pattern of research was to begin by preparing enrichment cultures of organisms of interest. From these, pure cultures were obtained. The next step was to undertake investigations of the morphology, physiology and biochemistry of the organisms under study. Last but not least came an analysis of their taxonomy and evolutionary relationships. For his thesis work, Stanier undertook a study of the Cytophaga, a group of bacteria that lived naturally in soil. They were distinctive in their ability to decompose agar and various forms of cellulose. Following the well-established pattern, Stanier began by preparing enrichment cultures of the Cytophagas. This was easily accomplished. Stanier simply incubated soil samples in a typical bacterial culture medium supplemented with filter paper to serve as the source of cellulose. Even easier, he simply placed particles of soil on filter paper laid over agar in Petri dishes. Typically, only one or two types of cellulose-decomposing bacteria would form a small cluster around the soil particle. It was then relatively simple to prepare pure cultures. Once this was accomplished, Stanier followed the standard plan and carried out detailed observations on the morphology of the bacteria. The cytophagas were especially interesting to observe because they showed various kinds of motility. Stanier observed and described these carefully. He then turned to comparative study of the physiology of soil and marine cytophagas, determining their carbon and nitrogen requirements, and analyzing the physical and chemical aspects of cellulose decomposition. He concluded with a lengthy taxonomic study. Here he considered the status of the organisms on the species level, and the meaning of the higher order groupings of organisms.

Of all of van Niel's students, Stanier was the most captivated by the ambition to make microbiology into a wissenschaftlich science. To signal that his kind of microbiological research was culturally sophisticated, Stanier adorned his dissertation with a quotation from a classic text of the French Enlightenment, Diderot's De l'interprétation de la nature:

When we have formed in our minds one of these systems which demands to be verified by experience, it is necessary not to attach ourselves to it in an opinionated manner nor to abandon it lightly. We think sometimes that these conjectures are false when we have not taken adequate measures to find them true. By virtue of multiplying attempts, if we do not encounter what we are looking for, it is possible that we discover for the better. The time we spend to question nature is never entirely lost.⁽⁶³⁾ When the first part of Stanier's dissertation was published in Bacteriological Reviews, he retained this quotation. It was probably the first (and possibly only) time Diderot was quoted in any publication sponsored by the SAB.⁽⁶⁴⁾

The second part of Stanier's dissertation leapt from a close study of a specific group of bacteria to a more expansive and ambitious project, the classification of all bacteria. Stanier convinced van Niel that a publication on the subject should be jointly authored by them. Van Niel rarely appended his names to his student's papers, but in this case he agreed, perhaps because the subject matter was close to his own interests. In this paper, Stanier and van Niel launched an attack on the empirical approach to bacterial classification represented in Bergey's Manual, the standard handbook of bacterial classification produced by the SAB. Their critique was similar to the one made by Kluyver and van Niel in 1936. As their major objection, Stanier and van Niel considered the Bergey system to be devoid of theory; useful in practice perhaps, but biologically meaningless.⁽⁶⁵⁾

Van Niel and Stanier opened their 1941 joint article with a quotation from Goethe. Making reference to this cultural icon gave notice that their paper was no mundane empirical work in bacteriology. It also gave them an opportunity to make a veiled jab at medical bacteriology:

Where this Science is concerned,

It is so difficult to avoid the wrong path,

There lies in it so much hidden poison,

And from physic is there scarcely any difference.⁽⁶⁶⁾ Stanier and van Niel emphasized the importance of constructing systems of bacterial classification in terms of phylogenetic relationships. They argued that a classification system based on phylogenetic arguments was valuable even if it were admittedly hypothetical, because it could guide future research. They criticized "empirical" bacteriologists who had claimed that bacteria do not exhibit enough characteristics from which evolutionary relationships could be inferred. They proposed to reexamine this question.

In the first place, Stanier and van Niel found the Bergey's definition for bacteria as a group to be completely unacceptable.⁽⁶⁷⁾ For example, it did not give criteria that would exclude fungi or most of the protozoa from the category of bacteria. On the other hand, by its own terms, the definition excluded well-accepted bacterial members of the Thiobacteriales. This was an especially irritating exclusion, as the purple photosynthetic bacteria central to van Niel's research were members of this group. The definitions for the seven orders in Bergey's manual, claimed Stanier and van Niel, were no less ambiguous.

Defining bacteria as biological entities was a central problem for Stanier and van Niel because they were committed to developing microbiology as a general science of life. Further, they considered themselves to be leading theoreticians of general microbiology. For both reasons, it was incumbent upon them to provide a clear biological definition for bacteria. They identified two primary questions in urgent need of settlement: What organisms should be included with a natural group of bacteria? How can that group be defined? "Admittedly," they wrote, "it is a difficult task to frame a definition of the Schizomycetes [the bacteria] adequate to include all organisms which belong here but sufficiently specific to exclude other groups of microorganisms."⁽⁶⁸⁾

The authors critically reviewed criteria that could be used for determining the natural relationships of bacteria. In particular, they discussed whether morphological or physiological criteria should weigh more heavily, a question addressed earlier by van Niel and Kluyver. As in the earlier work, Stanier and van Niel argued for the priority of morphological criteria. After surveying the bacteria, Stanier and van Niel proposed a classification scheme, essentially a modified version of the one proposed by Kluyver and van Niel in 1936.

Stanier and van Niel then returned to the issue of defining the bacteria in general. They identified three features common to the organisms generally recognized as bacteria: 1. Absence of true nuclei; 2. Absence of sexual reproduction; and 3. Absence of plastids.⁽⁶⁹⁾ These features were also shared by a group of pigmented organisms called blue-green algae. These organisms carried out oxygenic photosynthesis as plants did and were usually classified in the Plant Kingdom. The resemblance between bacteria and blue-green algae had led Cohn in the nineteenth century to regard bacteria as primitive plants. Now Stanier and van Niel came to a different conclusion. "Thus," they wrote, "we are forced to realize that on a morphological basis alone the separation of the bacteria and the blue-green algae is impossible."⁽⁷⁰⁾ But rather than unite these organisms into one category within the plants as Cohn had done, Stanier and van Niel argued that the bacteria and blue-green algae should be awarded kingdom level status on their own:

if a purely morphological definition of the bacteria fails to keep out the members of the blue-green algae, the obvious conclusion would seem to be the creation of a kingdom in which the Myxophyta [blue-green algae] and the bacteria constitute the two at present recognizable divisions....⁽⁷¹⁾ Stanier and van Niel followed a suggestion made by Herbert Copeland, a California naturalist, who had also argued for a kingdom for the bacteria and blue-green algae. Copeland recruited an old term for this proposed new kingdom, "the Monera," a word coined by Haeckel in the nineteenth century. Stanier and van Niel concurred: "Since Copeland's arguments seem sound, the name Monera will be adopted here."⁽⁷²⁾

Stanier and van Niel were adamant that bacteria should not be treated as primitive plants, as they were in Bergey's Manual. Awarding bacteria their own kingdom served both intellectual and social purposes. As long as bacteria were seen as primitive plants, theoretical bacteriology might be seen as a minor part of botany. If bacteria were worthy of kingdom level status, then one could argue that a distinct field was necessary for their study. In the middle of the nineteenth century, numerous attempts were made to establish new kingdoms of organisms beyond the traditional bifurcation of the natural world into plants and animals. None of these proposals were widely accepted.⁽⁷³⁾ It would be interesting to determine to what degree disciplinary politics presented an obstacle to these proposals.

The proposal made by Stanier and van Niel met with little response in the 1940's. The problem of defining bacteria appeared more urgent to them than it did to a wide group of researchers. Bergey's Manual continued to be the most widely used system of classification in the United States. It left the bacteria as a class within the Plant Kingdom. Van Niel and Stanier returned to the problem of defining bacteria as biological entities two decades later in a new intellectual and disciplinary context with a different impact.

In the 1940's, van Niel was well pleased with Stanier and his work. He saw Stanier as a worthy scion of the Delft tradition in microbiology. In 1941, he wrote to Barker that Stanier:

is more of a Beijerinck- than of a Kluyver type....His interests are not particularly along biochemical lines; I suppose that this is due to too limited a training and experience with chemical procedures. Theoretically, he likes to think about these matters, but in actual practice a proposed chemical study seems to frighten him. Nevertheless, both Beijerincks and Kluyvers fulfill their rôle, and it is impossible to decide whose is the more important.⁽⁷⁴⁾ By the time he had completed his dissertation research, Stanier had become a complete disciple of van Niel. He, too, had adopted the project to make microbiology into a general science of life with a well-developed set of principles and practices. In 1942, he assessed the costs of the dominance of bacteriology by medical questions in acerbic terms:

the unfortunate and inevitable consequence has been that most bacteriologists have centered their attention on thirty or forty important eubacterial parasites to the virtually complete neglect of the remaining thousands of species. Hence, even today, our understanding of bacteria as biological entities remains fragmentary and disorganized. Morphology, taxonomy, ecology, in the wider sense -- none of these phases has even been surveyed, let alone developed in a systematic way. The consequent deficiencies in our fundamental knowledge are a continual source of misunderstanding and a bar to further scientific development whose seriousness is only now beginning to become generally realized.⁽⁷⁵⁾ This passage, a sort of manifesto for general microbiology, introduced the issues that would preoccupy Stanier for the next four decades. Again, Stanier noted that understanding bacteria as biological entities, rather than as pathogens, was the key issue for general microbiology. It became his life's work to survey and systematize research on the morphology, taxonomy, and ecology of microorganisms, especially bacteria.

The critique of Bergey's Manual by Stanier and van Niel was one more skirmish in an ongoing conflict between the new theoretical microbiologists and "old-guard" in the SAB. The SAB controlled the most important America publications for research on microorganisms, in particular the Journal of Bacteriology. C. E. A. Winslow, the chief editor of the journal, was a committed medical bacteriologist, hostile to van Niel's approach to microbiology. Winslow routinely rejected papers from van Niel and his students, especially those that included enrichment culture studies. When a paper by Barker was rejected by the Journal of Bacteriology in 1939, van Niel was very irritated. He wrote to Barker:

it is a sound and -- from my way of looking at microbiological literature-- really desirable sort of paper, vastly superior to many of the scientific contributions which are regularly published by Winslow's journal. It is hard to guess why they do not care to print it there; possibly one of the reasons is that practically no one there understands what enrichment cultures are and mean....Let us ostracize the Journal of Bacteriology until some moves can be made to get rid of the present management.⁽⁷⁶⁾ Barker made one last try before giving up. In response, van Niel wrote, "Thanks for the Winslow-dope. As I told you, they do not know what an enrichment culture is, nor do they appreciate the possibilities! I suppose that this finishes our already very slender connection with the J.B.!"⁽⁷⁷⁾ Van Niel advised Barker to submit the manuscript to the Archiv fr Mikrobiologie, a German journal of which Kluyver was an editor. ⁽⁷⁸⁾

Doudoroff, too, looked down upon the medical bacteriologists who dominated the SAB and controlled its publications. The editors of Bergey's Manual, he wrote to Stanier, "seem to lack any knowledge of microorganisms." The classification of the Acetobacter and Azotobacter groups of bacteria were hopelessly confused in the new 1939 edition of Bergey's manual, he thought. In Doudoroff's opinion, this result revealed a profound lack of understanding on the part of the editors. He wondered if it was even worth trying to educate them.⁽⁷⁹⁾ Until World War II, van Niel and his students published their major work almost exclusively in European journals. Occasionally, their articles appeared in Bacteriological Reviews, founded in 1937. Though sponsored by the SAB, the journal was edited by Barnett Cohen, a proponent of general microbiology. After 1941, when access to European journals ended, much of the work of van Niel and colleagues appeared in the once-scorned Journal of Bacteriology. Publishing in this journal became much easier for van Niel and his students after 1945 when James M. Sherman, a microbiologist more sympathetic to general microbiology, succeeded Winslow as editor-in-chief.

E. More Physicists and Diverse Research

From 1936 to 1941, van Niel continued to develop his general microbiology as a wissenschaftlich science by building connections between microbiology and physics. Photosynthesis was a key problem that provided common ground. During this period, van Niel welcomed many distinguished physicists to his laboratory, several of whom were refugees from Nazi Germany. He also continued to cultivate research in the biochemistry of microbial metabolism.

The physicist William Arnold served as one important link between van Niel's laboratory and elite physics. In the spring of 1937, Arnold arrived for a prolonged stay in van Niel's laboratory. Already well-known for research with Emerson and his work on the "photosynthetic unit," he began his stay by taking van Niel's microbiology course. He then went on to carry out biophysical studies on photosynthesis. Van Niel and Arnold collaborated on a method to make quantitative estimations of bacteriochlorophyll.⁽⁸⁰⁾

In 1939, Arnold made plans to visit Niels Bohr's laboratory in Copenhagen to learn about artificial radioactivity. He had also considered going to Delft to work with Kluyver and Ornstein on the biophysics of photosynthesis. Van Niel supported Arnold's proposal to visit Bohr because it might "teach us interesting things about photosynthesis."⁽⁸¹⁾ After a year of study with Bohr, Arnold returned to the HMS. Very interested in radioactive isotopes, he soon established connections with the physicists at the Radiation Laboratory in Berkeley. There, E.O. Lawrence and his colleagues were producing new elements and isotopes with the cyclotron.⁽⁸²⁾ Through Barker and Arnold, van Niel made contact with Berkeley and the photosynthesis researchers at Stanford.

In April 1938, Gaffron, van Niel's former opponent in photosynthesis, arrived at the HMS. A refugee from Nazi policies, Gaffron had received a six-month fellowship from the RF. Despite the gravity of his situation and his interest in working with van Niel, Gaffron was not granted an extension by the RF. Van Niel wrote to Kluyver that he found the decision by the RF officials incomprehensible.⁽⁸³⁾ Fortunately, Gaffron was able to secure a position at the University of Chicago.

The summer of 1938 brought another distinguished physicist, James Franck, to Stanford. Franck's research on energy transfer in atomic collisions had won the Nobel Prize for him and his colleague Gustav Hertz in 1926. Franck immigrated from Nazi Germany to the United States in 1935. In 1938, he was appointed professor of physical chemistry at the University of Chicago, where a new laboratory for photosynthesis had been established. Before assuming this position, he spent the summer at Stanford. Franck and van Niel arranged a joint seminar series to discuss problems of photosynthesis. Van Niel considered Franck to be extraordinarily intelligent and congenial.⁽⁸⁴⁾

The physicist Max Delbrück also visited van Niel in the summer of 1938. At the time, Delbrück was on an extended tour of American genetics laboratories. Delbrück had come to the United States in 1937 with the support of the Rockefeller Foundation. Delbrück's mission was to identify research problems in biology that could be approached with the analytical, quantitative methods of physics. Photosynthesis had been an obvious candidate. A member of Gaffron's circle in Berlin, Delbrück seriously considered working in the area of photosynthesis research. He later said he chose not to enter the field because of its contentiousness, caused in part by Warburg's dominance.⁽⁸⁵⁾ In the United States, Delbrück visited the major genetics laboratories to look for promising projects. By the time he arrived at Morgan's laboratory at Caltech, he was already somewhat discouraged by the complexities of Drosophila genetics and its esoteric terminology. In 1938, Delbrück encountered a biological phenomenon more suited to his intellectual temperament, the replication of bacteriophage. This process became the centerpiece of Delbrück's research for the next several years.⁽⁸⁶⁾

In the summer of 1940, Delbrück enrolled in van Niel's course in General Microbiology, along with eight other students. That year, Stanier acted as teaching assistant.⁽⁸⁷⁾ The experience may have been a crucial part of Delbrück's transition from research in physics to biology. There was probably no better place in the world for Delbrück to learn the basics of microbiology. In both van Niel and Stanier, Delbrück encountered microbiologists who shared an ideal of science as a great cultural project. Van Niel was a master of the very field Delbrück had just entered, and was committed to teaching general microbiology. Van Niel would have affirmed the view that research on simple organisms like bacteria and bacteriophage would yield fundamental, not idiosyncratic, insights about life. At the same time, Delbrück's enrollment in van Niel's course would have enhanced its credibility and status among physical scientists. It may be taken as evidence that van Niel's microbiology was judged to be wissenschaftlich.

Van Niel's course may also have served as an important institutional model for Delbrück. In 1945, Delbrück established a summer course in bacteriophage genetics at the Cold Spring Harbor laboratory, the purpose of which was to recruit researchers to take up the problem of replication of bacteriophage. It was a tremendous success and became renowned in the history of molecular biology.⁽⁸⁸⁾

Delbrück's connections to van Niel and his participation in van Niel's course have been overlooked in previous studies. One cause of this omission may be that the summer of 1940 falls in between Delbrück's support by the RF and his professorship at Vanderbilt University. Thus, the archival record is faint for this interval in Delbrück's career. Regrettably, there is no known extant correspondence between van Niel and Delbrück, which makes a definitive assessment of their interactions difficult. The role of disciplinary politics in encouraging the production of histories in which Delbrück's work would loom large and van Niel's would disappear is discussed in Chapter V.

Delbrück did not, of course, become a microbiologist. He may be counted as a "dissenter." He turned what he learned from van Niel toward his own intellectual agendas, initially the study of phage replication, and then the study of the gene. In these respects, Delbrück regarded bacteria as instruments or tools for the investigation of molecular processes, rather than as organisms in nature to be understood for themselves. As we shall see in the next chapter, Delbrück's conception of bacteria was shared by an increasing number of investigators in the 1950's and 1960's. We shall also see that in the 1940's and 1950's, van Niel's circle of students and colleagues interlaced with Delbrück's in important ways.

In the late 1930's, the landscape of research in biochemistry and cellular metabolism continued to be changed by new developments. One of the most important of these was the increasing recognition of the importance of phosphate metabolism in cellular energetics. The study of phosphate metabolism, like photosynthesis, concerned the flow of energy in living things. It provided a biochemical explanation for energy relations. It connected neatly with the elucidation of the tricarboxylic acid cycle or "Kreb's cycle," also underway in the 1930's.⁽⁸⁹⁾ Hermann Kalckar, a leading researcher in this field from Denmark, brought expertise in phosphate metabolism to van Niel's laboratory in 1939.⁽⁹⁰⁾ He, too, enrolled in the microbiology course, along with three other students and three auditors, while Carson served as the assistant.⁽⁹¹⁾ Kalckar then went on to visit Berkeley and Caltech. Later, he became an active member of the "phage group" for a time.

Van Niel soon incorporated these new topics into his teaching and research. In the summer of 1941, William McElroy joined seven others in taking the microbiology course, while his friend Howard Bliss worked as the teaching assistant. A recent graduate of Stanford, McElroy had been convinced to switch from a pre-medical to biological curriculum by the tireless campaigner Taylor and by working with Blinks. Van Niel introduced McElroy to two scientific problems that developed into the core of his career: bioluminescence and phosphate bond energy. The physicist Arnold introduced McElroy to a new and exceptionally useful tool for studying phosphate metabolism, the radioactive isotope of phosphorous, ³²P.

Delbrück, Kalckar, and McElroy illustrate that a widening group of investigators were turning to microorganisms for experimental material by the late 1930's. Because van Niel's course was dedicated to the teaching of tools, rather than the propagation of a limited research agenda, his students were free to initiate new intellectual programs with the powerful techniques he gave them. In particular, there was always the possibility that the microorganism could be converted into a technology for the study of other problems. Researchers interested in microorganisms as tools formed a new constituency for van Niel's course. Many of them were not interested in microbiology per se. They saw microbiology as a resource to be turned to new intellectual agendas. McElroy was conscious of not becoming a disciple of microbiology: "I am not a true microbiologist, but I have used microorganisms as tools to study biological processes all my life." Nonetheless, he judged that "van Niel's influence in stimulating my interests was critical to my future research career."⁽⁹²⁾ McElroy went on to become professor of biology at Johns Hopkins University, the Director of the National Science Foundation from 1969 to 1972, and then Chancellor of the University of California, San Diego.

Experimental biology at Stanford continued to thrive in late 1930's, with van Niel very much a central player. In 1937, Taylor succeeded in convincing geneticist George Beadle to join the School of Biology. "With his help we are going to continue to make biological history at Stanford," Taylor wrote to Wilbur.⁽⁹³⁾ Taylor encouraged Beadle to spend some time with van Niel. "Dr. Beadle will probably spend most of the year with Dr. van Niel and Dr. Blinks at the Marine Station in order to have their help in carrying on his research," he wrote Wilbur.⁽⁹⁴⁾ In the fall, Edward L. Tatum joined Beadle as Research Associate, bringing another talented experimentalist to Stanford.

For his first three years at Stanford, Beadle continued to attempt to analyze the relationships between mutations and phenotypes in Drosophila, a project he began in 1933. In 1940, Beadle achieved an insight that led to a new approach to his research and to a new organism. Beadle has written that the idea of obtaining mutants blocked in a specific reaction occurred to him while he was auditing a course Tatum was giving in "comparative biochemistry."⁽⁹⁵⁾ He then proposed preparing nutritional mutants in the bread mold Neurospora as a way to analyze the relationship between genes and gene action. Beadle and Tatum pursued this approach and achieved a key breakthrough in their research on genetics and metabolism. Their research on nutritional mutants in Neurospora allowed them to make a new kind of distinction between genes and enzymes and to conceive of their relation in a new way. Beadle and Tatum advanced the hypothesis that the function of each gene was to direct the formation of one enzyme that catalyzed a reaction in a metabolic pathway. This developed into the important "one gene-one enzyme" doctrine.⁽⁹⁶⁾

There is no direct evidence that van Niel played a direct role in this research. However, it is abundantly clear that he had been promoting the use of microorganisms for fundamental studies at Stanford for a decade. Further, van Niel was on good terms with Beadle and Tatum and interacted with them frequently. In 1942, for example, van Niel and Tatum taught "General Microbiology" jointly on the Stanford campus. While Tatum gave about a third of the lectures, the frame and organization were all van Niel's. Given van Niel's mission to make the microbe a key organism for biological research, it is plausible that Beadle and Tatum discussed the advantages of working with Neurospora with van Niel. Beadle later wrote that Neurospora was an "obvious" choice, but retrospective claims of that kind are often oversimplifications.⁽⁹⁷⁾

There is a more subtle point to be made. Kluyver's comparative biochemical approach may have stimulated the thinking of Beadle and Tatum. To distinguish between genes and gene action, Beadle and Tatum obtained a series of mutants with blocks at different steps in a biochemical pathway. The series of biochemical mutants used by Beadle and Tatum resembled very strongly Kluyver's series of naturally occurring bacteria. If they weren't familiar with the approach before coming to Stanford, they almost certainly would have been introduced to it by van Niel. In 1941, Tatum considered Kluyver important enough to give his name as an identification on exams for undergraduates.⁽⁹⁸⁾ Further, the logic and method of selecting nutritional mutants used by Beadle and Tatum bears a strong resemblance to the elective culture technique, a major feature of van Niel's course in microbiology. Van Niel emphasized the value of the technique for directing the selection of naturally occurring strains of bacteria. It could easily be adapted to the selection of mutants produced in the laboratory.

Van Niel, Beadle, and Tatum, along with Blinks and Whitaker, were central figures in Stanford's program in experimental biology. Under Taylor's leadership, it produced consistently high quality research. While Taylor's program was much smaller than that at Caltech or at the University of Chicago, it won grants from the RF every year from 1934 to 1939. In 1939, the RF awarded the group as a whole a grant of $200,000 to be administered over a ten year period. The grant action called them "an extraordinarily able group of young investigators with interests centered in modern experimental biology."⁽⁹⁹⁾

Taylor capped the decade of success of Stanford biology in 1939 by hosting an international symposium to celebrate the centennial of the cell theory. Many of the most prominent investigators of the day accepted Taylor's invitation to speak. Among the participants were Wendell M. Stanley, speaking on viruses; Albert Szent-Gyorgi on vitamins; Edwin G. Conklin on cell and protoplasm concepts; and Ross G. Harrison on cellular differentiation. Taylor had wanted Kluyver to represent microbiology and Warburg to speak on photosynthesis. Kluyver declined on for logistical reasons; Warburg simply declined.⁽¹⁰⁰⁾ For Wilbur, "The Stanford Symposium on the Cell and Protoplasm" and other conferences that summer demonstrated that his University was no longer just a farm, but "a center of intellectual culture and scientific activities...."⁽¹⁰¹⁾ Van Niel, too, had achieved a central place in experimental biology. Van Niel spoke in Kluyver's place; he and Taylor represented the Stanford faculty for the final program.

By the end of the 1930's, van Niel's project to reform microbiology had accomplished much. In March of 1940, van Niel wrote to Kluyver about a major success. Doudoroff, "one of my best co-workers," had been appointed to the faculty at Berkeley, this time within the citadel of the Department of Bacteriology, specifically to teach general microbiology.⁽¹⁰²⁾ With Barker already there, Doudoroff would be the second microbiologist strongly influenced by van Niel to join the Berkeley faculty. The prospects for expanding general microbiology at Berkeley appeared bright.

F. From Idyll to War

Kluyver did not respond to van Niel's letter. He had planned for months to travel to the United States to attend the Third International Congress for Microbiology in New York City during the first week of September, 1939. Kluyver had been invited to give a research lecture and to participate in the Nomenclature Committee meeting, which he expected to be contentious. He looked forward to visiting as many American colleagues as possible, but most especially to seeing van Niel.⁽¹⁰³⁾ Van Niel, too, looked forward to a reunion with his mentor from the Netherlands.⁽¹⁰⁴⁾ Scheduled to arrive in New York on August 31, his steamship tickets purchased and his luggage tags neatly filled out, Kluyver canceled the trip just before departing because of the ominous situation in Germany. A few days later, while the microbiologists gathered in New York, the German army invaded Poland; Europe went to war. On May 10, 1940, the German army invaded the Netherlands. Four days later, the Netherlands capitulated and communications with the United States came to an abrupt end. Van Niel lost all contact with Kluyver.

For van Niel, the war in Europe reinforced his belief that the scientific outlook should be a cornerstone of civilization. Van Niel described his philosophy of science in a lengthy introduction to a colloquium on "Growth and Metabolism" given at Oregon State College in March 1941. He set out to justify studying biology while a great part of the world was at war. Van Niel described the process of science as a gradual accumulation of facts followed by the making of interpretations of the facts. "Theories, explanations, hypotheses -- they are but different names for interpretations," he wrote. Van Niel emphasized that interpretations must be abandoned when they can not account for newly discovered phenomena. Thus, interpretations could only be tentative. Van Niel concluded:

The truly scientific spirit implies the constant realization of the tentative nature of our ideas, and it is this outlook in particular which should -- and ultimately will -- contribute to the development of tolerance and to devising rational means for settling disputes and controversies without the use of violence.⁽¹⁰⁵⁾ In December 1941, the entry of United States into the war brought the idyllic period at the marine station to an end. Wartime conditions created new moral and political realities for scientists. It provided new opportunities for research and a new kinds of obligations to the government and the public. American scientists adjusted to these new realities in various ways. Most readily accepted the making of science into a crucial ally in the defense of democracy.⁽¹⁰⁶⁾ For many, the conception of science as a quest for truth and its role in defending democracy were morally linked. Both conceptions provided science with a profoundly moral purpose. The overwhelming practical demands of wartime transformed the science that van Niel sought to practice as a spiritual quest into an urgent practical necessity.

Wartime demands diverted personnel, facilities, and intellectual work toward military aims. Physicists were, of course, in especially high demand. On December 3, 1941, van Niel's colleague Arnold notified Wilbur that he was being considered for a defense-related position, ostensibly to work in Fire Control Research.⁽¹⁰⁷⁾ Eight days later, after the Japanese attack on Pearl Harbor, Arnold wrote to Wilbur again. This time Arnold reported that the appointment to the defense position was definite; he would leave Pacific Grove within the week.⁽¹⁰⁸⁾

Like physicists, biologists had important roles to play in the war effort. At Stanford, Taylor suggested to Wilbur that the School of Biology increase training in parasitology and nutrition. Beadle proposed that some of his work on Neurospora could be placed in service of the military and civilian nutrition problems. He had worked out methods for assaying the presence of vitamins and other growth factors.⁽¹⁰⁹⁾ Whitaker eventually went to Washington, D.C. to become Executive Secretary of the Division of Biology and Agriculture of the National Research Council.⁽¹¹⁰⁾

Van Niel, too, adjusted to the new political and moral realities of wartime. In the fall of 1941, he became an American citizen.⁽¹¹¹⁾ Van Niel divided his time between war related work and the continuation of projects he had begun earlier. In one project, van Niel collaborated on research to determine if rubber could be produced from the guayule plant. Van Niel welcomed the opportunity to contribute to research on this project.⁽¹¹²⁾

Microbiologists of all kinds proved to be valuable to the war effort in a variety of ways. Medical bacteriologists were recruited to attempt to handle the always serious problem of infectious disease among the troops. Some bacteriologists were recruited to take part in a secret program to develop biological weapons. By 1945, nearly four thousand people were employed at four top-secret biological warfare installations in the United States.⁽¹¹³⁾ Microbiologists also provided essential expertise in the effort to develop effective antibiotics. Microbiologist Selman Waksman played a major role in exploiting knowledge about the ecology of microorganisms for antibiotics research. A Russian emigre, Waksman became a well-respected soil microbiologist at the New Jersey Agricultural Experiment Station affiliated with Rutgers.⁽¹¹⁴⁾ A great admirer of van Niel and Kluyver, Waksman considered himself a great supporter of general microbiology. Waksman was elected President of the SAB in 1942.

Waksman perceived that the war presented unique opportunities for soil and general microbiology to increase their status, visibility, and institutional standing as fields. As President of the SAB, he was in a position to take advantage of these opportunities. "The year 1942 will remain a memorable one in the History of Bacteriology," he wrote to the Society. "Although the War clouds were already accumulating and were throwing their deep shadows, the outlook for the entire field of Bacteriology...and the Society...were of the brightest." Waksman declared, "It was essential...that Bacteriology be officially recognized as an Independent Science and not merely as a branch of Medicine, or of Agriculture, or of Industry." Waksman was pleased to report success. "As a result of the Emergency, a new and important 'War Committee on Bacteriology' was appointed," he informed the SAB. As a result, "bacteriologist," rather than "medical bacteriologist," was recognized as a distinct category for the purposes of the National Roster of Scientific and Specialized Personnel and the Selective Service Board. Winning this recognition allowed Waksman to conclude with satisfaction that "Medical Bacteriology is only a branch of Bacteriology...."⁽¹¹⁵⁾

Waksman's fellow promoters of an "independent" bacteriology were overjoyed. One enthusiast replied to Waksman, "I want to express my approval and thanks for your report contained in the last News Letter...The energetic action resulting in the official recognition of Bacteriology as independent science is a high accomplishment. It has taken many years to break the apron strings so benignly knotted by Popsy Welch and other less well-meaning pathologists."⁽¹¹⁶⁾

Waksman's promotion of the importance of soil and general microbiology was solidly grounded in crucially important research. The successful transformation of penicillin from a tenuous promise into an apparent miracle demonstrated the value of soil and general microbiology with a forcefulness rhetoric could not approach. General microbiology, like physics, was transformed by the war from an esoteric specialty into a resource for the nation.

As a leading general microbiologist, van Niel became indirectly involved in the effort to make penicillin into a safe, effective, and economical remedy. Many of his students and colleagues made direct contributions. Foster, who had obtained his Ph.D. with Waksman, spent the year 1939 to 1940 at the HMS as an NRC Fellow working with van Niel. During that time, he investigated bacterial photosynthesis. He found unambiguous support for the view that organic compounds are hydrogen donors in bacterial photosynthesis.⁽¹¹⁷⁾ After his postdoctoral year with van Niel, Foster became a research microbiologist at Merck and Co., Inc. By 1942, he was the head of the Microbiology Section at Merck and a leader in the company's research on penicillin. Soon after obtaining his Ph.D., van Niel's student Carson joined Foster in working for Merck.⁽¹¹⁸⁾

In 1942, Merck granted a research fellowship to van Niel's laboratory from which Foster expected great things. "I know only too well from past experience," he wrote, "what an ambitious and indubitably profitable program you have in mind for this fantastic substance called penicillin." He promised that a small amount of penicillin would be sent shortly, and that van Niel would be given as much as he needed for his research. Van Niel's graduate student, Bliss, was given the choice problem of determining the mechanism of penicillin action.⁽¹¹⁹⁾ Van Niel's penicillin project did not produce great results. However, his expertise and counsel were valued and may have made an important general contribution to the overall project. He kept in touch with both Foster and Carson and asked Stanier to send copies of dissertations from the Laboratory of Microbiology in Delft to Carson at Merck.⁽¹²⁰⁾

Exhibiting impressive initiative in antibiotics research, Merck was the first company to produce penicillin for treatment and was the most successful manufacturer during the war.⁽¹²¹⁾ It was the first company to use the submerged culture technique for growing the mold that produced penicillin. This unconventional technique had been developed in Kluyver's laboratory in Delft in the mid-1930's. The suggestion from several American scientists that Kluyver's technique be adapted for penicillin production was received most enthusiastically at Merck, which employed several scientists like Foster, who were admirers of van Niel and Kluyver.⁽¹²²⁾ This innovation greatly facilitated large-scale production of penicillin. By 1943, Merck was producing over 2,000 million units of penicillin per month, or 100 times more than firms who continued to use conventional cultures.⁽¹²³⁾

In 1943, van Niel was asked to attend a penicillin conference organized by Merck. Wilbur advised him to go, while suggesting that Merck pay something toward the traveling expenses.⁽¹²⁴⁾ At the conference, van Niel met his colleagues Foster and Carson. Together, they reminisced about the "old days" at the marine station before the war. This did not cheer him, he wrote to Stanier, but filled him with foreboding and sense of decline. He was completely worn out, he said, by the time he got back to Stanford after the conference.⁽¹²⁵⁾

Like Foster, Carson, and Bliss, Stanier placed his expertise in microbiology in service of penicillin production. After completing his doctoral thesis in 1942, Stanier returned to his native country as Junior Bacteriologist at the National Research Council of Canada. Two years later, he joined a Canadian subsidiary of Merck & Co., Inc. in Montreal as director of penicillin production. During the war, most of Canada's penicillin was produced by this company.⁽¹²⁶⁾

Research directed toward practical problems took precedence during the war, but scientists also took advantage of wartime conditions to carry out fundamental research. For some, it was an especially productive period. Research of all kinds seemed to have a new value. Perhaps it was simply possible to justify late nights in the laboratory in a new way. Wartime research generated new methods and techniques that scientists were eager to test on all kinds of problems.

At the Radiation Laboratory in Berkeley, defense work and fundamental studies were intermingled. The availability of radioisotopes had made possible a whole new approach to the analysis of metabolic reactions. Compounds could be synthesized that contained a radioactive atom. The biochemical fate of that compound could then be traced because radioactivity was easily detected. At Berkeley's Radiation Laboratory, Sam Ruben, Martin Kamen, and colleagues were quick to use the new technique to attempt to identify definitively the biochemical origin of the oxygen evolved in photosynthesis.⁽¹²⁷⁾ Warburg continued to assert that photosynthetic oxygen derived from the splitting of carbon dioxide. Van Niel and colleagues had argued since 1929 that the oxygen arose from the splitting of water. Ruben and Kamen set out to resolve the controversy by tracing the path of radioisotopes of oxygen. They incubated algal cells with either water containing ¹⁸O or bicarbonate containing ¹⁸O. For each condition, they determined whether the oxygen evolved photosynthetically contained ¹⁸O. They showed that only when water contained ¹⁸O did the isotope appear in the evolved oxygen. This work provided the best direct evidence that the oxygen did indeed derive from the water.⁽¹²⁸⁾ Warburg, however, never accepted the results or the conclusion. The majority of photosynthesis researchers did.

Van Niel took advantage of the connections he had built with colleagues at the Radiation Laboratory. He conducted some of first metabolic tracer studies with metabolites labeled with the especially useful radioisotope, ¹⁴C. In a series of experiments in 1942, van Niel and colleagues utilized ¹⁴C to trace directly the biochemical fate of carbon dioxide in the metabolic reactions of protozoa and the propionic acid bacteria.⁽¹²⁹⁾

Meanwhile, van Niel continued his exhaustive studies on the Athiorhodaceae, or "non-sulfur purple" and "brown" bacteria. A companion to his major work of 1932 on the purple bacteria, this research investigated the culture, general physiology, morphology, and classification of the non-sulfur purple bacteria. These bacteria were pigmented and photosynthetic like the purple bacteria, but did not metabolize hydrogen sulfide; hence their awkward name. Van Niel completed the study in 1944 and published it in an American journal.⁽¹³⁰⁾

During the war, the microbiology course became smaller and smaller as enrollments at Stanford dropped. In the summer of 1942, there were five students, with Bliss acting as assistant. In the fall of 1942, van Niel's thoughts turned toward the war ravaging Europe. While ostensibly describing the consequences of specialization, van Niel quoted this passage from Romain Rolland's Life of Beethoven:

The air feels heavy around us. The old Europe suffocates in a laden and vicious atmosphere. A materialism without grandeur weighs on the mind, and impedes the work of governments and individuals. The world dies of asphyxia in its proud and vile egotism -- the world succumbs.⁽¹³¹⁾The following year, only three students enrolled. Van Niel's graduate student, Dixie Lee Ray, acted as assistant.

At Stanford, major administrative changes contributed to the passing of an era. In 1943, both Fisher and Wilbur retired from the positions they had held for a quarter of a century. Fisher departed with one last, desperate, and ineffectual exhortation for the station to focus on marine biology.⁽¹³²⁾ But the appointment of Blinks as the new Director of the marine station meant that experimental research had won ascendance over the sciences represented by Fisher. Stanford welcomed Donald Tresidder, a physician, as its new president. Wilbur was convinced to accept an appointment as Chancellor so that he could act in an advisory capacity.

During the war, industry and academia competed for competent microbiologists as demand exceeded supply. In the tight market, students of van Niel were especially valuable commodities. In 1944, a scientist at Caltech lamented to Delbrück, then at Vanderbilt, "There are no microbiologists on the market; any one with even the slightest pretensions in the field has been snapped up by firms interested in manufacturing penicillin...In the present situation you are probably lucky to have the one student of Van Niel's [sic] who is working for you."⁽¹³³⁾

In 1944, only one postdoctoral fellow, Mortimer P. Starr, joined van Niel's laboratory. He stayed for two years and took up the study of bacterial plant pathogens.⁽¹³⁴⁾ In 1944, there were no students at all for van Niel's microbiology course.

By 1945, van Niel was dispirited. He had lost interest in microbiology, he wrote to Stanier. His thoughts had turned toward history and philosophy and he considered seriously writing an essay on scientific philosophy.⁽¹³⁵⁾ Van Niel's success in practicing science as a kind of spiritual quest for truth could only be partial and provisional. It depended on the particular circumstances in which he lived. World War II created new moral and political conditions for science and scientists. The imperatives of war forced van Niel to accept that under certain circumstances the attainment of practical ends took moral precedence over the spiritual search for truth. In confronting that reality and in desiring to escape it, van Niel had much in common with Martin Arrowsmith.

The dropping of atomic bombs on Hiroshima and Nagasaki in August 1945 complicated the moral landscape for many scientists.⁽¹³⁶⁾ In the aftermath of these events, it was perhaps impossible to recover fully the faith that science was fundamentally a spiritual quest for truth. If that ideal was compromised, it was not abandoned. For some, it acquired a new moral power in the postwar era.

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1. Barker to Pearl Murray, February 11, 1969; HAB.

2. See Jonathan Harwood, Styles of Scientific Thought: The German Genetics Community, 1900-1933 (Chicago: University of Chicago Press, 1993), pp. 189-90, 276-83, for discussion of these concepts.

3. See, e.g., van Niel to Kluyver, July 10, 1938; AJK; van Niel, "Growth and Metabolism," unpublished lecture, March 8, 1941; VNG.

4. J. Howard Brown, "The Biological Approach to Bacteriology," Journal of Bacteriology, 23 (1932), 1-10.

5. For an examination of research on bacterial physiology that addressed both fundamental and medical problems, see Olga Amsterdamska, "From Pneumonia to DNA: The Research Career of Oswald T. Avery," Historical Studies in the Physical and Biological Sciences, 24 (1993), 1-40. For a detailed study of Marjory Stephenson's research see Robert E. Kohler, "Innovation in Normal Science: Bacterial Physiology," Isis, 76 (1985), 162-181. On research at Iowa State, see Rivers Singleton, Jr., "From Bacteriology to Biochemistry: Albert Jan Kluyver and Chester Werkman at Iowa State," manuscript submitted, 1998.

6. See, e.g., van Niel, "A Plea for General Microbiology," lecture given 193_. VNG

7. The portrait of the course contents given here is a composite drawn from van Niel's teaching notes from 1930 to 1941, which contain outlines of the lectures and the laboratory exercise, and the complete lecture notes from 1942 (VNA). The quotations are from the latter unless otherwise designated. Notes taken by students in the course were also consulted, especially those by Barker, (HAB) and Addicott (VNS 114-129/124). In the spring quarters of 1933 and 1934, when he was working frequently in Hermann Spoehr's laboratory, van Niel taught "General Microbiology" on the main Stanford campus. Otherwise, the course was given at the HMS.

8. C. Stacy French, "Fifty Years of Photosynthesis," Annual Review of Plant Physiology, 30 (1979), 1-26 on 4-5.

9. Bulletin of the HMS, 1918-1940.

10. Bulletin of the HMS, 1929.

11. Bulletin of the HMS, 1930.

12. Robert Hungate, "Evolution of a Microbial Ecologist," Annual Review of Microbiology, 33 (1979), 1-20, on 3-4; Interview with Robert Hungate, July 1, 1993.

13. Robert Hungate, "Cornelis Bernardus van Niel, 1897-1986," Photosynthesis Research, 10 (1986), 139-142 on 141.

14. Hungate, "Evolution of a Microbiologist," (1979), on 4.

15. Van Niel to Barker, September 28, 1978; HAB 6/44; Horace A. Barker, "Explorations of Bacterial Metabolism," Annual Review of Biochemistry, 47 (1978), 1-33.

16. Interview with H.A. Barker, Berkeley, Spring, 1989. Barker, "Explorations of Bacterial Metabolism," (1978), on 4.

17. Van Niel to Kluyver, February 10, 1935; AJK.

18. W.D. McElroy, "From the Precise to the Ambiguous: Light, Bonding and Administration," Annual Review of Microbiology, 30 (1976), 1-20 on 5; van Niel to Stanier, August 13, 1941; RYS 6/21.

19. McElroy, "Light, Bonding and Administration," (1976), on 5.

20. William Whiteman Carlton Topley and Sir Graham S. Wilson, The Principles of Bacteriology and Immunity (Baltimore: Wood, 1929); Sir Graham S. Wilson and A.A. Miles, Topley and Wilson's Principles of Bacteriology and Immunity (Baltimore: Williams & Wilkins Co., 1946).

21. Notes for a course in General Microbiology, dated 1932; VNS 7/4.

22. Van Niel, "General Microbiology," (1942), p. 1; VNA.

23. Ibid., pp. 1-4.

24. See Robert E. Kohler, Lords of the Flies: Drosophila Genetics and the Experimental Life (Chicago: University of Chicago Press, 1994), 19-27 for an interesting interpretation in ecological terms of how organisms cross the boundary between nature and the laboratory.

25. Van Niel, "General Microbiology," (1942); VNA.

26. Cf. Susan Leigh Star and James R. Griesemer, "Institutional Ecology, 'Translations' and Boundary Objects: Amateurs and Professionals in Berkeley's Museum of Vertebrate Zoology, 1907-1939," Social Studies of Science, 19 (1989), 387-420.

27. Donald Fleming, "Emigré Physicists and the Biological Revolution," Perspectives in American History, 2 (1968), 152-189; Evelyn Fox Keller, "Physics and the Emergence of Molecular Biology: A History of Cognitive and Political Synergy," Journal of the History of Biology, 23 (1990), 389-409.

28. Doris T. Zallen, "Redrawing the Boundaries of Molecular Biology: The Case of Photosynthesis," Journal of the History of Biology 36, (1993), 65-87.

29. Robert Emerson and William Arnold, "A Separation of the Reactions of Photosynthesis by Means of Intermittent Light," Journal of General Physiology, 15 (1932), 391-420.

30. Fisher to Wilbur, April 2, 1934; RLW 85/HMS.

31. Fisher to Wilbur, January 22, 1934; RLW 85/HMS.

32. Wilbur to Fisher, January 23, 1934; RLW 85/HMS.

33. Fisher to Wilbur, April 2, 2934; RLW 85/HMS.

34. See Garland E. Allen, Life Sciences in the Twentieth Century (Cambridge: Cambridge University Press, 1975), pp. 174-75, for an illustration and explanation of this apparatus.

35. Van Niel to Kluyver, February 10, 1935; AJK.

36. Van Niel to Kluyver, February 10, 1935; AJK. ("voelt zich meer en meer tot do zuivere (en toegepaste) mikrobiologie aangetrokken.")

37. Cold Spring Harbor Symposium on Quantitative Biology, (1933), p. v.

38. Cold Spring Harbor Symposium on Quantitative Biology, (1935); van Niel to Kluyver, February 10, 1935; AJK.

39. C.B. van Niel, "Photosynthesis of Bacteria," Cold Spring Harbor Symposium on Quantitative Biology, 3 (1935), 138-150 on 143.

40. Ernst P. Fischer and Carol P. Lipson, Thinking About Science: Max Delbrück and the Origins of Molecular Biology (New York: Norton, 1988), on 216.

41. This is the assessment of plant physiologist Jack Myers. See his "Conceptual Developments in Photosynthesis, 1924-1074," Plant Physiology, 54 (1974), 420-466.

42. Hans Gaffron, "Van Niel's Theory: Thirty Years After," in H. Gest, A. San Pietro, and L.P. Vernon, eds., Bacterial Photosynthesis (Yellow Springs, Ohio: Antioch Press, 1963), 3-14 on 6.

43. Van Niel to Kluyver, August 23, 1935; AJK.

44. Van Niel to Wilbur, October 18, 1935; RLW 91/HMS.

45. A.J. Kluyver and C.B. van Niel, "Prospects for a Natural System of Classification of Bacteria," Centralblatt Bakteriologie und Parasitenkunde II. Abteilung, 94 (1936), 369-403; reprinted in A.R. Kamp, J.W.M. La Rivière, and W. Verhoeven, eds., Albert Jan Kluyver: His Life and Work (Amsterdam: North Holland, 1959), 282-317 on 283-284.

46. C.B. van Niel, "On the Metabolism of the Thiorhodaceae," Archiv für Mikrobiologie, 7 (1936), 323-358.

47. Gaffron, "Van Niel's Theory," (1963), 3-14.

48. Using radio-labeled compounds, Stanier and Doudoroff showed that non-sulfur purple bacteria were capable of the direct uptake of organic compounds like acetate and butyrate in the light. Michael Doudoroff and R.Y. Stanier, "Role of Poly-beta-hydroxybutyric acid in the Assimilation of Organic Carbon by Bacteria," Nature, 183 (1959), 1440-42.

49. This suggestion was made by R.Y. Stanier in "Photosynthetic Mechanisms in Bacteria and Plants: Development of a Unitary Concept," Bacteriological Reviews, 25 (1961), 1-17 on 6-7.

50. Van Niel to Kluyver, February 8, 1936; AJK.

51. Van Niel to Kluyver, February 28, 1936; AJK.

52. Van Niel to Kluyver, April 23,1936; van Niel to Kluyver, June 28, 1936; AJK.

53. H. A. Barker, "On the Biochemistry of the Methane Fermentation," Archiv für Mikrobiologie, 7 (1936), 404; H.A. Barker, "On the Fermentation of Glutamic Acid," Enzymologia, 2 (1937), 175; H.A. Barker, "The Production of Caproic and Butyric acids by the Methane Fermentation of Ethyl Alcohol," Archiv für Mikrobiologie, 8 (1936), 415.

54. F.W. Waller to Barker, July 17 1936; HAB 5/4.

55. Interview with Horace A. Barker, Berkeley, CA, 1989.

56. Barker to van Niel, May 3, 1936; HAB 6/44.

57. See, e.g., Barker to van Niel, September 30, 1938; HAB 6/44.

58. R. Y. Stanier, "The Journey, Not the Arrival, Matters," Annual Reviews of Microbiology, 34 (1980), 1-48 on 9.

59. M. Doudoroff, "Lactoflavin and Bacterial Luminescence," Enzymologia, 5 (1938-39), 239-243.

60. Stanier, "The Journey," (1980), on 9.

61. Ibid.

62. Van Niel to Kluyver, March 10, 1940; AJK. ("Hij heeft de beestjes om hun zelfs wille lief....")

63. I thank Professor Roger Hahn for assistance in translating this passage. Stanier retained the original French. "Quand on a formé dans sa tête un de ces système qui demandent a etre verifiés par l'expérience, il ne faut ni s'y attacher opinâtrement, ni l'abandonner avec légreté. On pense quelquefois de ses conjectures qu'elles sont fausses, quand on n'a pas pris les mesures convenables pour les trouver vraies. A force de multiplier les essais, si l'on ne recontre pas ce que l'on cherche, il peut arriver qu'on recontre mieux. Jamais le temps qu'on emploie interroger la nature n'est pas entirement perdu."

64. R.Y. Stanier, "The Cytophaga Group: A Contribution to the Biology of the Myxobacteria," Bacteriological Reviews, 6 (1942), 143-196.

65. R.Y. Stanier and C.B. van Niel, "The Main Outlines of Bacterial Classification," Journal of Bacteriology, 42 (1941), 437-466.

66. Ibid., p. 437. "Was diese Wissenschaft betrifft, Es is so schwer, den falschen Weg zu meiden, Es liegt in ihr so viel verborgnes Gift, Und von der Arzenie ist's kaum zu unterscheiden."

67. D.H. Bergey, Manual of Determinative Bacteriology, (Baltimore: Williams & Wilkins Co., 1939).

68. Stanier and van Niel, "Bacterial Classification," (1941), p. 430.

69. Ibid., p. 449.

70. Ibid., p. 455.

71. Ibid., p. 456.

72. Ibid.; Herbert F. Copeland, "The Kingdoms of Organisms," Quarterly Review of Biology, 13 (1938), 383-420.

73. Lynn J. Rothschild, "Protozoa, Protista, Protoctista: What's in a Name?" Journal of the History of Biology, 22 (1989), 277-305.

74. Van Niel to Barker, November 23, 1941 and December 13, 1941; HAB 6/44.

75. Stanier, "The Cytophaga Group," (1942), p. 144.

76. Van Niel to Barker, April 25, 1939; HAB 6/44.

77. Van Niel to Barker, June 22, 1939; HAB 6/44.

78. See, e.g., van Niel to Barker, April 25, 1939; van Niel to Barker, June 22, 1939; HAB 6/44.

79. Doudoroff to Stanier, June 21, 1943; RYS 5/11.

80. C.B. van Niel and W.A. Arnold, "The Quantitative Estimation of Bacteriochlorophyll," Enzymologia 5, (1938), 244-250.

81. Van Niel to Kluyver, July 10, 1938; AJK.

82. See J.L. Heilbron and Robert Seidel, Lawrence and His Laboratory: A History of the Lawrence Berkeley Laboratory (Berkeley: University of California Press, 1989) for a detailed account of the Radiation Laboratory in the 1930's.

83. Van Niel to Kluyver, July 10, 1938; AJK.

84. Van Niel to Kluyver, July 10, 1938; AJK; H.G. Kuhn, "James Franck," in Charles L. Gillispie, ed., Dictionary of Scientific Biography (New York: Scribner, 1971,) 117-118.

85. Max Delbrück, Oral History Transcript, May-June 1980, pp. 55-56; CIT.

86. See Lily E. Kay, "Conceptual Models and Analytical Tools: The Biology of Physicist Max Delbrück," Journal of the History of Biology, 18 (1985), 207-246 for a detailed look at Delbrück's career. See also Fischer and Lipson, Thinking about Science (1988).

87. Van Niel, "General Microbiology," (1940), VNA.

88. See, e.g., John Cairns, James D. Watson, and Gunther S. Stent, eds., Phage and the Origins of Molecular Biology (Cold Spring Harbor Laboratory of Quantitative Biology, 1966) for a hagiographic assessment of Delbrück and the phage group.

89. See Allen, Life Sciences (1975), Chapter VI for a brief overview.

90. See Hermann Kalckar, "High Energy Phosphate Bonds: Optional or Obligatory?" in Cairns et al., Phage and the Origins of Molecular Biology (1966), 43-52.

91. Van Niel, "General Microbiology," (1939), VNA.

92. McElroy, "Light, Bonding and Administration," (1976), p. 5.

93. Taylor to Wilbur, April 5, 1937; RLW 93/Biology, School of.

94. Ibid.

95. George W. Beadle, "Recollections," Annual Review of Biochemistry, 43 (1974), 1-13 on 8.

96. George W. Beadle and E. L. Tatum, "Genetic Control of Biochemical Reactions in Neurospora," Proceedings of the National Academy of Sciences (U.S.A.), 27 (1941), 499-506.

97. Beadle, "Recollections," (1974), p. 8.

98. Edward L. Tatum, "Final Exam, 1941," RU 450, T189 32/1; RAC.

99. "Resolution," April 5, 1939; RF; RG 1.1; 205D; 8/13; RAC. Beadle was given additional funding from 1937 to 1939 under separate RF grant actions.

100. Van Niel to Kluyver, December 7, 1938; AJK.

101. Edgar E. Robinson and Paul C. Edwards, eds., The Memoirs of Ray Lyman Wilbur, (Stanford: Stanford University Press, 1960), on 575.

102. Van Niel to Kluyver, March 10, 1940; AJK.

103. Kluyver to van Niel, June 28, 1939; AJK.

104. Van Niel to Kluyver, May 27, 1945; AJK.

105. Van Niel, "Growth and Metabolism," unpublished lecture, March 8, 1941, p. 3.; VNG.

106. Daniel J. Kevles, The Physicists: The History of a Scientific Community (New York: Alfred A. Knopf, 1978), 287-89; David A. Hollinger, "Science as a Weapon the Kulturkämpfe in the United States During and After World War II," Isis, 86 (1995), 440-54.

107. Arnold to Wilbur, December 3, 1941; RLW 118/HMS.

108. Arnold to Wilbur, December 12, 1941; RLW 118/HMS.

109. Beadle to Wilbur, October 22, 1942; RLW 121/Biology-School of 1942-43.

110. Whitaker to Wilbur, January 23, 1943; RLW 121/Biology-School of 1942-43.

111. Wilbur to Herbert Gasser, April 18, 1941; RLW 113/Hopkins Marine Station.

112. Fisher to David Spence, November 2, 1942; RLW 123/HMS.

113. Robert Harris and Jeremy Paxman, Higher Form of Killing: The Secret Story of Chemical and Biological Warfare (New York: Hill and Wang, 1982), pp. 95-100.

114. Selman Abraham Waksman, My Life With Microbes (New York: Simon and Schuster, 1954).

115. S.A. Waksman, "President's Letter," Society of American Bacteriologists Newsletter, vol. VIII., (December 1942), pp. 2-3; ASM.

116. Barnett Cohen to Waksman, January 1, 1943; SAW-ASM.

117. C.B. van Niel, "The Comparative Biochemistry of Photosynthesis," in James Franck and W. E. Loomis, eds., Photosynthesis in Plants (Iowa State College Press, 1949), 437-495 on 445.

118. Van Niel to Stanier, May 31, 1942; RYS 6/21.

119. Jackson W. Foster to van Niel, October 19, 1942; VNG.

120. Van Niel to Stanier, June 28, 1942; RYS 6/21.

121. W.H. Helfand, H.B. Woodruff, K.M.H. Coleman, and D.L. Cowen, "Wartime Industrial Development of Penicillin in the United States," in John Parascandola, ed., The History of Antibiotics: A Symposium (Madison: American Institute of the History of Pharmacy 1980), pp. 36-38.

122. Ibid. Waksman was consultant to Merck at this time, too. The Northern Regional Research Laboratory of the U.S. Department of Agriculture also played a role in developing submerged cultures technique. It would interesting to determine if there were any connections between this laboratory and Kluyver or van Niel.

123. Ibid., p. 43.

124. Wilbur to van Niel, August, 23, 1943; RLW 123/HMS.

125. Van Niel to Stanier, October 7, 1943; RYS 6/21.

126. Stanier, "Journey" (1980), p. 10.

127. Martin D. Kamen, Radiant Science, Dark Politics: A Memoir of the Nuclear Age (Berkeley: University of California Press, 1985), especially chapters 5 and 6.

128. S. Ruben, M. Randall, M. Kamen, and J.L. Hyde, "Heavy Oxygen (¹⁸O) as a Tracer in the Study of Photosynthesis," Journal of the American Chemical Society, 63 (1941), 877-879. See also Kamen, Radiant Science (1985), p. 140.

129. See, e.g., S.F. Carson, S. Ruben, M.D. Kamen, J.W. Foster, and C.B. van Niel, "Radioactive Carbon as an Indicator of Carbon Dioxide Utilization. VIII. The Role of Carbon Dioxide in Cellular Metabolism," Proceedings of the National Academy of Sciences, 28 (1942), p. 8015, and M.B. Allen and S. Ruben, "Tracer Studies with Radioactive Hydrogen: Some Experiments on Photosynthesis and Chlorophyll," Journal of the American Chemical Society, 64 (1942), pp. 948-50. See Kamen Radiant Science (1985), p. 311 for a complete list of references to this work.

130. C.B. van Niel, "The Culture, General Physiology, Morphology, and Classification of the Non-sulfur Purple and Brown Bacteria," Bacteriological Reviews, 8 (1944), 1-118.

131. This lecture was given on October 2, 1942.

132. Fisher to Wilbur, June 17, 1943; RLW 123/HMS.

133. E.R. Buchman to Delbrück, February 22, 1944; MD 4/38. The student in question was A. Doermann.

134. Van Niel, "Education," (1967), p. 24.

135. Van Niel to Stanier, January 30, 1945; RYS 6/21.

136. Kevles, Physicists (1978), 332-36.