olga amsterdamska - waseda university since the late nineteenth century, the study of microorganisms

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  • P1: JYD 9780521572019c17 CUUS457/Bowler 978 0 521 57201 9 January 6, 2009 0:21

    17

    MICROBIOLOGY

    Olga Amsterdamska

    The only constant characteristics of a research area that we can, anachronis- tically, describe as microbiology might be the minute size of the organisms it studies and its reliance on instruments and a set of techniques that allow us to see beyond the range of what is visible to the naked eye. Stability or continuity are difficult to find elsewhere – either in the range and classifica- tion of microorganisms, in the types of questions asked about them, in the theoretical or practical goals of research, in the institutions in which investi- gations were conducted, or in the composition of the group of scientists to whom these microscopic organisms were of interest.

    The range of organisms encompassed by these investigations has changed many times during the last two centuries. Relatively undifferentiated infu- soria gave place to protists and schizomycetes, and later to protozoa, bacte- ria, fungi, and algae; the invisible filterable viruses, obligate parasites, and lytic principles appeared only temporarily, to be replaced by rickettsia and viruses. These microorganisms were investigated by a heterogeneous assem- bly of amateurs, botanists, zoologists, biologists, pathologists, biochemists, geneticists, medical doctors, sanitary engineers, agricultural scientists, veteri- narians, public health investigators, biotechnologists, and so on. Specialisms and disciplines devoted to specific groups of microorganisms – bacteriol- ogy, virology, protozoology, and mycology – have disparate though often overlapping institutional and intellectual histories, and although the term “microbiology” dates from the last decades of the nineteenth century, it did not come to designate a discipline that could claim its own sphere of concern until after the Second World War. Even then, the discipline remained both intellectually and institutionally heterogeneous.

    Since the late nineteenth century, the study of microorganisms has been dominated by practical concerns such as the protection of public health and the struggle against human or animal disease, or the production of wine, beer, foodstuffs, or industrial chemicals. Today, genetic manipulation of microorganisms plays an important role in biotechnological innovations.

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    Microbiological research also played a pivotal role in many fundamental theoretical controversies within biology – in the debates on spontaneous gen- eration, cell theory, the nature of life, classification, speciation, heredity and its mechanisms, and others – and in some of its more revolutionary tran- sitions, such as those from descriptive, morphological, or “natural history” styles of research to experimental biology, or in the development of general biochemistry and, later, molecular biology.

    Microorganisms were only rarely studied for their own sake. As the small- est living creatures, they were expected to yield a critical understanding of macroscopic life. They provided a limit – as the simplest organisms, the most bountiful and ingenious ones, the earliest and most primitive, the most adaptable, the most varied and changeable, the most quickly reproducing, or the easiest to transform – against which a variety of general biological claims were tested. As organisms responsible for various fermentations, microor- ganisms could be used to probe and manipulate the production of many foodstuffs and chemicals, but also to study general biochemistry. As little metabolic factories, they could be harnessed – and today also changed and manipulated – to produce useful substances. When regarded as pathogens, their study promised a means to understand and control human, animal, or plant disease. In genetic or biochemical research, microorganisms were likely to be used as laboratory tools or instruments and to provide insight into metabolic pathways or mechanisms of hereditary transmission.

    Given this variety of contexts and concerns, it is difficult to write a history of microbiology that does justice to both the intellectual and institutional complexity of the field’s development.1 In the discussion here, an attempt is made to emphasize the changing interactions between studies of microorgan- isms conducted in different intellectual and institutional contexts, between research in which microorganisms were used as tools and research that focused on microbes as distinct organisms, and between studies that aim to answer basic biological questions and those devoted to the practical applications of microbiological knowledge.

    SPECIATION, CLASSIFICATION, AND THE INFUSORIA

    Throughout the eighteenth century, microorganisms were difficult to see and even harder to understand. The use of microscopes – especially of single-lens

    1 All existing general histories of microbiology (and bacteriology) are by now fairly dated, but the most comprehensive ones are Hubert A. Lechevalier and Morris Solotorovsky, Three Centuries of Microbiology (New York: McGraw-Hill, 1965), and Patrick Collard, The Development of Microbiology (Cambridge: Cambridge University Press, 1976). The history of medical bacteriology until World War II is discussed in William Bulloch, The History of Bacteriology (Oxford: Oxford University Press, 1938), and W. D. Foster, The History of Medical Bacteriology and Immunology (London: Heinemann, 1970).

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    318 Olga Amsterdamska

    instruments – required a substantial degree of skill and patience, while the images produced by compound microscopes were often blurred, with each object surrounded by a fringe of colors. Working with microscopes that pro- duced as much doubt as conviction, and without a framework into which to fit their observations of the “infusoria” – as microscopic organisms have been called since the 1760s – only a few eighteenth-century naturalists attempted more than detailed descriptions of the individual miniscule creatures first observed by the Dutch draper Antoni van Leeuwenhoek (1632–1723). Carl Linnaeus himself placed all microorganisms in an order “Vermes” in a class he referred to as “Chaos.”

    In the course of the nineteenth century, however, studies of microorgan- isms became more important, and disputes about them came to reflect a number of interrelated controversies in biology. After the 1820s, new achro- matic microscopes became available, increasing both the magnification and the sharpness of the images. But the steadily increasing ability to differentiate the organization of the various microorganisms and to see infusoria that had previously been invisible did not settle the existing disagreements among experts. Learning to prepare the specimens and to see through a microscope was a complex process, and it often generated new foci of opposition and controversy among the microscopists.

    One such controversy surrounded the theories of the German naturalist Christian Gottfried Ehrenberg (1795–1876), whose classification of infuso- ria was an elaboration and extension of an eighteenth-century classification of the Danish naturalist Otto Friedrich Müller (1730–1784). In Die Infu- sionsthierchen als vollkommene Organismen (1838), Ehrenberg described and classified hundreds of microorganisms and attempted to show that despite the great variety of their forms, all infusoria had a full set of organ systems and functions. Ehrenberg particularly emphasized the ubiquity and com- plexity of their digestive system, which his new achromatic microscopes allowed him to see.2 In 1841, this “polygastric theory” of infusoria was vehemently criticized by the French zoologist Felix Dujardin (1801–1860). Although Dujardin used an admittedly inferior microscope, he concluded that Ehrenberg “has yielded too easily to the rapture of his imagination.”3

    The disagreements between Ehrenberg and Dujardin were related less to the differences between what they could or could not see through their respective microscopes than to their more general beliefs about the nature of the organic world.

    Questions of general biological interest – how, if at all, infusoria were to be classified, the nature of their morphological structure, how they develop and

    2 Frederick B. Churchill, “The Guts of the Matter – Infusoria from Ehrenberg to Bütschli: 1838–1876,” Journal of the History of Biology, 22 (1989), 189–213.

    3 John Farley, The Spontaneous Generation Controversy from Descartes to Oparin (Baltimore: Johns Hopkins University Press, 1974), p. 55.

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    evolve, and how they fit into the rest of the plant and animal world – were the basis of botanists’ and zoologists’ interest in microorganisms from the 1840s through the 1870s. In 1845, Karl Theodore von Siebold (1804–1885), a zoologist at the University of Freiburg, reclassified the infusoria by drawing a distinction between bacteria and other microorganisms, which he called protozoa. A proponent of the cell theory, he removed bacteria to the plant kingdom (because their motions were involuntary rather than directed) and installed “unicellular” microorganisms as the simplest forms of organisms both in the plant and in the animal kingdoms. The p