Summary In 1979, Robert C. Olby published an article titled ?Mendel no Mendelian??, in which he questioned commonly held views that Gregor Mendel (1822?1884) laid the foundations for modern genetics. According to Olby, and other historians of science who have since followed him, Mendel worked within the tradition of so-called hybridists, who were interested in the evolutionary role of hybrids rather than in laws of inheritance. We propose instead to view the hybridist tradition as an experimental programme characterized by a (...) dynamic development that inadvertently led to a focus on the inheritance of individual traits. Through a careful analysis of publications on hybridization by Carl Linnaeus (1707?1778), Joseph Gottlieb Koelreuter (1733?1806), Carl Friedrich Gärtner (1772?1850), and finally Mendel himself, we will show that this development consisted in repeated reclassifications of hybrids to accommodate anomalies, which in the end allowed Mendel to draw analogies between whole organisms, individual traits, and ?elements? contained in reproductive cells. Mendel's achievement was a product of normal science, and yet a revolutionary step forward. This also explains why, in 1900, when the report he gave on his experiments was ?rediscovered?, Mendel could be read as a ?Mendelian? (shrink)

This paper presents and discusses a series of hybridization experiments carried out by Nils Herman Nilsson-Ehle between 1900 and 1907 at a plant breeding station in Svalöf, Sweden. Since the late 1880s, the Svalöf station had been renowned for its ‘scientific’ breeding methods, which basically consisted of an elaborate system of record-keeping through which the offspring of individual plants were traced over generations while being meticulously described. This record system corresponded to a certain breeding technique and certain theoretical convictions . (...) Inspired by Tschermack’s translation of Mendel’s Pisum-paper, Nilsson-Ehle began his experiments in 1900 and published a first, major synthesis of his findings in 1908. If one compares these experiments as documented in the breeding records, with their representations in print, one encounters discrepancies in terms of procedure and presentation of data. This can be explained by the fact that Nilsson-Ehle was obliged to follow the recording and breeding procedures institutionalised at Svalöf, and these procedures, grounded in a taxonomic discourse, left little room for Mendelian hybridisation experiments. The twists and turns that this story takes are analysed in terms of Bachelardian philosophy of science, where the ‘epistemological obstacle’ functions as a central, analytic category. In contrast to Bachelard, however, I will characterise these obstacles as being of an institutional, rather than mental, nature. Thus characterized, moreover, they turn out to have been prerequisites as much as barriers to scientific progress. (shrink)

I call an experiment “crucial” when it makes possible a decisive choice between conflicting hypotheses. Joharmsen's selection for size and weight within pure lines of beans played a central role in the controversy over continuity or discontinuity in hereditary change, often known as the Biometrician-Mendelian controversy. The “crucial” effect of this experiment was not an instantaneous event, but an extended process of repeating similar experiments and discussing possible objections. It took years before Johannsen's claim about the genetic stability of pure (...) lines was accepted as conclusively demonstrated by the community of geneticists. The paper also argues that crucial experiments thus interpreted contradict certain ideas about the underdetermination of theories by facts and the theory-ladenness of facts which have been influential in recent history and sociology of science. The acceptance of stability in the pure lines did not rest on prior preference for continuity or discontinuity. And this fact permitted a final choice between the two theories. When such choice is characterized as “decisive” or “final”, this is not meant in an absolute philosophical sense. What we achive in these cases is highly reliable empirical knowledge. The philosophical possibility of drawing (almost) any conclusion in doubt should be distinguished from reasonable doubt in empirical science. (shrink)

: This article analyzes German debates on the microbiology of infectious diseases from 1865 to 1875 and asks how and when organic pollution in tissues became noteworthy for aetiology and pathogenesis. It was with Ernst Hallier's pleomorphistic microbiology that the organic character of alien material in tissues came to be regarded as important for pathology. The process that followed saw both vigorous biological critique and a number of medical applications of Hallier's work. Around 1874 contemporaries reached the conclusion that pleomorphous (...) vegetation was most likely of little importance if not accidental in relation to the aetiology of infectious diseases whereas the idea of monomorphous micro-organisms facilitated a causal explanation. It was only then that notions such a pure cultures, bacterial specificity, etc. favored by Ferdinand Julius Cohn and his school became popular in medical circles. (shrink)

This essay explores connections between bacteriology and the disciplinary evolution of biochemistry in this country during the 1930s. Many features of intermediary metabolism, a central component of biochemistry, originated as attempts to answer fundamental bacteriological questions. Thus, many bacteriologists altered their research programs to answer these questions. In so doing they changed their disciplinary focus from bacteriology to biochemistry. Chester Hamlin Werkman's (1893-1962) Iowa State career illustrates the research perspective that many bacteriologists adopted. As a junior faculty member in the (...) Bacteriology Department in the late 1920s, Werkman faced a powerful professional dilemma: establishing a research identity that distinguished him from his colleagues with flourishing national and international reputations. His solution was to radically alter his research program from traditional bacteriology to a biochemistry program, which reflected the influence of the Dutch microbiologist/biochemist, Albert Jan Kluyver (1888-1956). Werkman was extremely successful in this career change. His laboratory made significant contributions to biochemistry, and Werkman achieved a notable degree of personal success. His career began in the shadow of his departmental bacteriological colleagues; within a decade he became the department's dominant research figure, as a biochemist. Werkman's personal success, however, had profound consequences for the disciplinary future of bacteriology at Iowa State. (shrink)

Philosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. ‘Macrobe’ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes – the dominant life form on the planet, both now and throughout evolutionary history – will transform some of the philosophy (...) of biology’s standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology – including biofilm formation, chemotaxis, quorum sensing and gene transfer – that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations. (shrink)

In 1890, Sergei Nikolaevich Vinogradskii (Winogradsky) proposed a novel life process called chemosynthesis. His discovery that some microbes could live solely on inorganic matter emerged during his physiological research in 1880s in Strassburg and Zurich on sulfur, iron, and nitrogen bacteria. In his nitrification research, Vinogradskii first embraced the idea that microbiology could have great bearing on agricultural problems. His critique of agricultural chemists and Kochian-style bacteriologists brought this message to the broader agricultural community, resulting in an heightened interest in (...) biological, rather than chemical methods to investigate soil processes. From 1891 to 1910, he directed the microbiological laboratory at the Imperial Institute of Experimental Medicine in St. Petersburg, Russia, where he expanded his chemosynthesis research to a broad investigation of the manifold significance of autotrophic organisms in soil processes. This work and that of his students attracted the serious attention of agricultural chemists and soil scientists in Russia and abroad, changing essentially the way they understood and investigated the role of microbes in the soil. His student, Vasilii Omelianskii, effectively integrated Vinogradskii’s approach into Russian and Soviet, and international agricultural microbiology. Vinogradskii’s activities in the late 19th century reflect the changes occurring more broadly in science. At that time, microbiologists such as Louis Pasteur, Eugenius Warming, and Martianus Beijerinck were contributing new laboratory methods and theoretical perspectives to incipient disciplines closely related to agriculture: ecology, soil science, and soil microbiology. (shrink)

SummaryIt is argued that Hugo de Vries's conversion to Mendelism did not agree with his previous theoretical framework. De Vries regarded the number of offspring expressing a certain character as a hereditary quality, intrinsic to the state of the pangene involved. His was a shortlived conversion since after the ‘rediscovery’ he failed to unify his older views with Mendelism. De Vries was never very much of a Mendelian. The usual stories of the Dutch ‘rediscovery’ need, therefore, a considerable reshaping.