Bacteriology as a Cultural System: Analysis and its Discontents

I have not used “paradigms” or Fleck's “thought collectives” here to deflect attention from the primacy of the cognitive. Instead, warranting the pun is Clifford Geertz's 1964 essay, “Ideology as a cultural system”, in Apter D. (ed.), Ideology and discontent (New York, 1964), 47–76. Rejecting the view that ideologies were merely distortions, Geertz emphasizes their utility as simplifying systems in efficiently mediating the practical work of communication, allocation, categorization, and public action generally. Geertz's concept, like Herbert Simon's “satisficing” in economics, recognized the impracticality of being robustly rigorous in all directions simultaneously. Cf. Fleck Ludwik , Genesis and development of a scientific fact, ed. by Trenn T. J. Merton R. J. , transl. by Bradley Fred Trenn T. J. (Chicago, 1979); Simon Herbert , The sciences of the artificial (Cambridge, MA, 1969). Similar themes arose in Thomas Kuhn's paradigms about the same time, though the emphasis was on cognitive matters ( Kuhn Thomas , The structure of scientific revolutions (Chicago, 1962)). Geertz's essay was the jumping off point for a descriptive approach to technoscientific ideologies which I developed with Philip Shepard (Deep disagreement in U.S. agriculture: Making sense of policy conflict (Boulder, CO, 1993)).

This has begun to change. See Mendelsohn Andrew , “Cultures of bacteriology: Formation and transformation of a science in France and Germany, 1870–1914”, unpublished Ph.D. dissertation, Princeton University, 1996; Gradmann Christoph , Laboratory disease: Robert Koch's medical bacteriology, transl. by Forster E. (Baltimore, 2009).

Amsterdamska Olga , “Medical and biological constraints: Early research on variation in bacteriology”, Social studies of science, xvii (1987), 657–87.

Pickstone John , Ways of knowing: A new history of science, technology, and medicine (Manchester, 2000); idem, “Working knowledges before and after circa 1800: Practices and disciplines in the history of science, technology and medicine”, Isis, xcviii (2007), 2007–516; idem, “Commentary: From history of medicine to a general history of ‘Working Knowledges’”, International journal of epidemiology, xxxviii (2009), 2009–9.

Vernon Keith , “Pus, sewage, beer, and milk: Microbiology in Britain, 1870–1940”, History of science, xxviii (1990), 289–325; Schneider Daniel , Hybrid nature: Sewage treatment and the contradictions of the industrial ecosystem (Cambridge, MA, forthcoming).

A popular Soviet history of bacteriology reflects this orientation (see Lev Potkov , A world we do not see (Moscow, 1957)).

Fleck recognized the unaccountable character of such changes, using the image of the “vanguard” of an army as his chief metaphor. Genesis and development (ref. 1), 124.

Bulloch William , The history of bacteriology (Oxford, 1930). Terms like ‘dogma’, ‘orthodox’, and ‘heterodox’ arise regularly in the history of bacteriology; see Mendelsohn's objections: J. Andrew Mendelsohn, “‘Like all that lives’: Biology, medicine and bacteria in the age of Pasteur and Koch”, History and philosophy of the life sciences, xxiv (2002), 2002–36, see pp. 5, 19.

Mazumdar Pauline , Species and specificity (Cambridge, 1995).

Kohler Robert , “Innovation in normal science: Bacterial physiology”, Isis, lxxvi (1985), 162–81; idem, “Bacterial physiology: The medical context”, Bulletin of the history of medicine, lix (1985), 1985–74; Amsterdamska , “Medical and biological” (ref. 3); idem, “Stabilizing instability: The controversy over cyclogenic theories of bacterial variation during the interwar period”, Journal of the history of biology, xxiv (1991), 1991–222; idem, “Achieving disbelief: Thought styles, microbial variation, and American and British epidemiology, 1900–1940”, Studies in the history and philosophy of biology and the biomedical sciences, xxxv (2004), 2004–507; Brock Thomas , The emergence of bacterial genetics (Cold Spring Harbor, 1990); Summers William , “From culture as organism to organism as cell: Historical origins of bacterial genetics”, Journal of the history of biology, xxiv (1991), 1991–90; Mendelsohn , “‘Like all that lives’” (ref. 8); Löwy Ilana , “‘A river that is cutting its own bed’: The serology of syphilis between laboratory, society, and the law”, Studies in the history and philosophy of biology and the biomedical sciences, xxxv (2004), 2004–24; Anderson Warwick , “Natural histories of infectious disease: Ecological vision in twentieth-century biomedical science”, Osiris, 2nd ser., xix (2004), 2004–61.

The resurgence of interest in Fleck's work, following Bradley and Trenn's 1979 English translation, affected scholarship less than one might have expected. Generally, Fleck has seemed more relevant as a precursor of Kuhn and of SSK than as an historian of his own science.

Lakatos Imre , “Falsification and the methodology of scientific research programmes”, in Lakatos Musgrave Alan (eds), Criticism and the growth of knowledge (Cambridge, 1970), 91–196. Amsterdamska complained of the constraints of Kuhnianism: “Although many sociologists and historians of science argue that different scientific fields exhibit different patterns of cognitive development, the philosophical vocabulary used to describe cognitive structure has been based almost exclusively on the ideal of fundamental, theory-building sciences. Whether scientific development is considered a result of the hypothetico-deductive process of induction, or whether it is seen in terms of paradigms, progressive research programmes or problem-solving traditions, the focus has been on the construction of theory and the solution of theory-generated problems” (Amsterdamska, “Medical and biological” (ref. 3), 657; see also 659–60; idem, “Achieving disbelief” (ref. 10); Brock , Bacterial genetics (ref. 10)).

Smith David Martin Donald Conant Norman Beard Joseph Taylor Grant Kohn Henry Poston Mary , (eds), Zinsser's Textbook of bacteriology, 9th edn (New York, 1948; hereafter cited as Zinsser, 9th edn); Tanner Fred , Bacteriology (New York, 1937); Carter Charles , Microbiology and pathology, 3rd edn (St Louis, 1944). I have consulted also the 1939, 8th edn, of the Zinsser text, the last to list Zinsser as author (with Stanhope Bayne-Jones (New York, 1939)). Comparison of the two reinforces my decision to refer to the “Zinsser authors” rather than Zinsser. While the degree of difference varies from topic to topic, the changes are often toward a toning down of Zinsser's commentaries and speculations. A diachronic review of the evolution of this textbook would be valuable, but my interest here is in a snapshot of a mature science.

Tanner , Bacteriology (ref. 13), pp. vii–viii; Carter , Microbiology (ref. 13), 165. Brock was blunt: “bacteriologists immersed in their immensely technical and highly specialized studies, cared little about broader questions in biology (Bacterial genetics (ref. 10), 2). In criticizing this view, Mendelsohn, “‘Like all that lives’” (ref. 8) has argued that biological issues were more central than is usually recognized, but that they existed within a different conceptual regime, that of variation of virulence. “For this most medical and applied science has always seemed separate from the conceptual development of biology … and even epistemically incapable of contributing to it …, following my argument, bacteriology became experimental biology before biology itself is supposed to have become experimental” (p. 6). The acknowledgement of uncertainty and flux in the textbooks reflects the issues to which Mendelsohn calls attention; the great question then, is how that recognition of complexity was kept from undermining a stable basis for practice, the central issue for Amsterdamska (“Medical and biological” (ref. 2)).

Tanner , Bacteriology (ref. 13), 28.

Bulloch , Bacteriology (ref. 8). Cf. Mazumdar , Species (ref. 9), esp. pp. 44–5. Tanner , Bacteriology (ref. 13), 57–8; Amsterdamska , “Medical and biological” (ref. 3), 670; Mendelsohn , “‘Like all that lives’” (ref. 8).

“He [Koch] was aware that botanists did not regard different bacterial forms as distinct and constant species, and he agreed with Brefeld that the formation of distinct species can be justified only ‘when the whole history of development has been traced by cultivation from spore to spore’. Nevertheless, he argued that this 'theoretically correct demand cannot be made a sine qua non in every investigation of pathogenic bacteria. We should otherwise be compelled to cease our investigation into the etiology of infective diseases till botanists have succeeded in finding out the different species of bacteria by cultivation and development from spore to spore. It might then very easily happen that the endless trouble of pure cultivation would be expended on some form of bacterium which would finally turn out to be scarcely worthy of attention'” ( Amsterdamska , “Medical and biological” (ref. 3), 666–7).

” There is nothing medical in this belief in monomorphism; but, in the context of Koch's research programme, monomorphism, formulated so as to exclude the possibility of morphological or physiological variation in bacteria, was firmly embedded in the germ theory of disease and had clear medical ramifications” (Amsterdamska, “Medical and biological” (ref. 3), 663).

Zinsser , 9th edn (ref. 13), 230. Among those who would criticize this view, Fleck, (Genesis (ref. 1), 59, 117), attributed the origin of belief in microbial monocausal explanation to a pre-scientific age in which disease was seen as invasion by minute devils.

Carter , Microbiology (ref. 13), 165.

Carter , Microbiology (ref. 13), 171–2; Tanner , Bacteriology (ref. 13), 32.

Amsterdamska , “Stabilizing” (ref. 10); Kohler , “Innovation” (ref. 10), 171.

Associated with the work of Paul Ewald, this issue is sometimes presented as new. It has received great popular attention in recent decades in connection with the origin of HIV and the threat of new forms of flu: See Löwy Ilana , “Epidemics and populations”, Studies in the history and philosophy of biology and the biomedical sciences, xxxiii (2002), 187–94.

Zinsser , 9th edn (ref. 13), 112, 114. The authors recognize that bacteria may even “have been active agents in the natural selection of man and animals and plants”.

“… [D]isregard for variation was motivated not only by various methodological objections (which could always be invoked against work which did not seem to fit with the assumption of monomorphism) but also by the belief that such variations were practically irrelevant” ( Amsterdamska , “Medical and biological” (ref. 3), 670).

Mendelsohn , “Like all that lives” (ref. 8), 4–5, points to the emergence of “virulence” as an effectively irreducible organizing entity that did not require translation into pathology: “… at the center of this reorganization of bacteriological knowledge lay neither a theory nor a phenomenon clearly characterized according to one or more branches of science, but ‘virulence’. Virulence was an intellectually empty, almost purely operational concept: Virulent cultures killed, attenuated ones did not”.

Zinsser , 9th edn (ref. 13), 120. Mazumdar notes: “In Koch's experiments, the body of the animal was itself an apparatus for producing a pure culture of the organism, and at the same time and indicator of the properties of the species cultured: The disease was one of the differentia of the species, as constant as its length and breadth” (Species (ref. 9), 66).

Kohler , through his explorations of the emergence of biochemistry, has recognized the conflicts: “Chemists came to the study of microbes with a rather simplistic view of living organisms. Many medical chemists believed that microbes were essentially chemical catalysts and that the dramatic effects of infections were caused by simple chemical toxins produced by bacterial reactions.” Kohler notes the complaint of the maverick biochemist and pioneer in bacterial physiology, Marjory Stephenson: “chemists conceived of bacteria as convenient bags of enzymes to be extracted, separated, and examined in vitro” ( Kohler , “Innovation” (ref. 10), 164, 166–7).

Careers too, most conspicuously that of the organic chemist-bacteriologist Paul Ehrlich, exhibit the close ties. Ironically, it is the chemist Pasteur who liberates bacteriology from chemistry; the botanist-physician Koch who most closely models bacteriology on chemistry. As Mazumdar, in Species (ref. 9), 61, points out, the central role of staining bacteria with the new organic dyes arose out of the close personal and familial relations between Ehrlich, his cousin the organic chemist Carl Weigert, the pathologist Julius Cohnheim, the botanist Cohn, and the young Koch during years when all were working in Breslau.

Lewis Sinclair , Arrowsmith (New York, 1925), chap. 4, section IV.

Vernon , “Pus” (ref. 5); Maulitz Russell , “Pathology”, in The education of American physicians, ed. by Numbers Ronald (Berkeley, 1980), 138–9.

Kohler , “Bacterial physiology” (ref. 10); Amsterdamska , “Medical and biological” (ref. 3), 671.

Amsterdamska , “Medical and biological” (ref. 3), 667.

Baldwin Peter , Contagion and the State in Europe (Cambridge, 1999); Löwy , “River” (ref. 10).

Zinsser , 9th edn (ref. 13), 230, italics mine.

Summers, “Culture as organism” (ref. 10), notes that the concentration on colonies as units hampered recognition of statistics — Recognition that within a colony there would be a normal distribution of variability.

Carter , Microbiology (ref. 13), 165, italics mine; Tanner , Bacteriology (ref. 13), 83–4. See also Schneider , Hybrid nature (ref. 5).

Lewis , Arrowsmith (ref. 30), chap. 4, section IV.

In the 1930 film of the book, the ethics are highlighted beyond their status in Lewis's narrative: While the tone is ambivalent, much is made of the colonial governor's view that subjecting the population to an experiment of this source is a moral outrage. This long predates both Tuskegee and the reaction to it.

Fleck , Genesis (ref. 1), 55–65, 115.

Mazumdar , in Species (ref. 9), 52, 57, notes: “It is very difficult, on reading Cohn's paper, to disentangle from the web of relationships anything resembling either a dichotomous or a common ancestor classification.” Cf. Bulloch , Bacteriology (ref. 8), 193–4, 203: “It is true that some of the questions which he [Cohn?] raised are still in the melting-pot, and nowhere is this more apparent than with regard to the classification of bacteria…”.

Tanner , Bacteriology (ref. 13), 83; Zinsser , 9th edn (ref. 13), 135–6.

Zinsser , 9th edn (ref. 13), 59. See also Brock , Bacterial genetics (ref. 10); Summers , “Culture as organism” (ref. 10).

Effectively, the bacteriologists were practising a competitive exclusion principle long before it was articulated by the ecologist Gause (working with microorganisms) in the early 1930s. That is, they were defining species in terms of niche and niche in terms of species. Since no two species may occupy the same niche, one must either complicate (subdivide) niche or merge the apparently different species when this appears to be the case. Gause's apparent independence from institutional bacteriology is another example of the isolation of bacteriological ways of working and knowing from bacteriology at large.

“Chemists use periodic tables, and group closely related elements. They make such groups as halogens, alkali metals, heavy metals, rare earths, etc.” ( Tanner , Bacteriology (ref. 13), 84).

“In making cultures the medium most likely to grow the suspected organism or organisms and, in addition, the medium most likely to grow any organism that might be present should be chosen” ( Carter , Microbiology (ref. 13), 124; cf. Fleck , Genesis (ref. 1), 113–14).

See Fleck's ironic invocation of this principle (Genesis (ref. 1), 123).

Latour Bruno , The Pasteurization of France, transl. by Sheridan Alan Law John (Cambridge, MA, 1988).

King Lester , The road to medical enlightenment (London, 1970).

Frankland Edward , “On chemical changes in their relation to microorganisms”, Chemical news, ii (1885), 78–80; Kohler , “Innovation” (ref. 10), 189–1.

As Mendelsohn (“‘Like all things that live’” (ref. 8), 13) points out, Pasteur himself did not uniformly maintain this position: ” The specific fermentative or pathogenic effects of a given microbial species were relative to the milieu. Mycoderma aceti in wine, for instance, broke down alcohol into acetic acid and carbon dioxide, thus making vinegar. In vinegar, however, it turned the acetic acid into carbon dioxide and water”.

Zinsser , 9th edn (ref. 13), 59.

As its title indicates, the arch pleomorphist, Carl von Nägeli, in his book Die niederen Pilze in ihren Beziehungen zu den Infektionskrankheiten und der Gesundheitspflege, recognized a role for microbes in health and disease, but environment mediated microbial action ( Amsterdamska , “Medical and biological” (ref. 3), 663).

More than a half-century later, the audacity of that equating would be revealed in the first two of Evans's precepts on acute respiratory diseases: “1) The same clinical syndrome may be produced by a variety of agents; 2) The same etiological agent may produce a variety of clinical syndromes” ( Evans A. S. , Causation and disease: A chronological journey (New York, 1993), 46). Mazumdar (Species (ref. 9), 66) points to Koch's 1878 paper on wound infections, and notes that Koch had added “a new dimension to his definition of the bacterial species, that of the species of disease with which it is associated: The disease and the bacteria define each other…”.

Carter K. Codell , “Koch's Postulates in relation to the work of Jacob Henle and Edwin Klebs”, Medical history, xxix (1985), 353–74.

Mendelsohn (“‘Like all things that live’” (ref. 8)) considers such recognition of variability in the disease production by a supposed single species of microbe as evidence of the dominance of the concept of variable virulence by followers of Koch as well as of Pasteur. Virulence, he argues, effectively blended pleomorphist and monomorphist approaches, and served as a proxy for the exploration of many biological questions within bacteriology. Amsterdamska, “Medical and biological” (ref. 3) takes a more dichotomous view. She emphasizes the heuristic value of monomorphism for public health practice; while Mendelsohn (p. 5) is interested in “how the most applied and least theory-driven sciences may have intellectual shape”. To some degree, their differences may be explained by chronology and rhetorical situation. Mendelsohn focuses primarily on an earlier period; my own sense of Koch's views on cholera suggests a hardening of his position between 1884 and 1885, but also some variation with regard to rhetorical occasion (Christopher Hamlin, Cholera: The biography (Oxford 2009)). More important, however, is the coexistence within bacteriological orthodoxy of what are at any given time, if not contradictions, statements which effectively take the form: “bacterium X is the necessary and sufficient cause of disease Y except when it is not.” Further research, into both variable virulence and immunity, may better clarify the conditions under which cause accounts for effect. In the meantime, the practical advantages of monomorphism were far preferable to the anarchic implications of pleomorphism.

Zinsser , 9th edn (ref. 13), 112–13; Tanner , Bacteriology (ref. 13), 398.

Kohler , “Bacterial physiology” and “Innovation” (ref. 10); Summers , “Culture as organism” (ref. 10).

Tanner , Bacteriology (ref. 13), 78.

Bulloch , History of bacteriology (ref. 8), 217.

Tanner , Bacteriology (ref. 13), 89–91; Zinsser , 9th edn (ref. 13), 135.

Summers , “Culture as organism” (ref. 10); Brock , Bacterial genetics (ref. 10).

Tanner , Bacteriology (ref. 13), 84.

Tanner , Bacteriology (ref. 13), 90.

Zinsser , 9th edn (ref. 13), 152.

Zinsser , 9th edn (ref. 13), 125–6. Amsterdamska (“Medical and biological” (ref. 3), 675–6) recognizes that several of the domains in which bacteria varied — Enzymatic operations, serological capacities, and even mutation itself, were, ironically, translated into components of stability, and therefore, acquired taxonomic significance. “Initially reports of changes in fermentation characteristics of enteric bacteria were seen as a hindrance; by casting doubt on the validity of diagnostic tests they appeared to create new practical difficulties for bacteriological work.” “In investigations of antigenic structure, variation was no longer a subject but rather a useful method for investigating new problems … what was initially seen only as a hindrance to reliable clinical procedures was quickly transformed into a tool…”.

In fact, such unions are hardly rare, Pickstone (Ways of knowing (ref. 4)) reminds us: Most notably in medicine, crafts depend on a natural history of relevant active ingredients.

Zinsser , 9th edn (ref. 13), 77.

Hadley Philip , “Microbic dissociation: The instability of bacterial species with special reference to active dissociation and transmissible autolysis”, Journal of infectious diseases, xl (1927), 1–312, p. 2. Hadley, s magisterial review has intrigued both contemporaries and historians. Textbook authors recognize these varieties of instability, though they usually spread their discussion across multiple chapters (but see Carter , Microbiology (ref. 13), 76).

Zinsser , 9th edn (ref. 13), 59, 130.

Zinsser , 9th edn (ref. 13), 64; Latour , Pasteurization (ref. 48). As Kohler (“Innovation” (ref. 10), 179) notes, the potential range of measures of productivity was enormous: “Gale systematically measured the relative proportions of some twenty enzymes in E. coli as he varied the condition of growth: Acidity, nutrients, age of culture, aeration, and so on. A few patterns did emerge: Some enzymes seemed to increase in amount as if to compensate for adverse changes in the milieu; others seemed to proliferate only under conditions optimal for their activity.” But, as Kohler (“Bacterial physiology” (ref. 10)) points out, such explorations took place in the unorganized territory of biochemistry rather than the friendly confines of bacteriology.

Mendelsohn , “‘Like all things that live’” (ref. 8). As Amsterdamska (“Medical and biological” (ref. 3)) points out, “Koch's adherence to monomorphism was not simply a precondition of the germ theory of disease, but a guarantee that the aetiological connections he could establish by laboratory investigation would have relevance for the practical medical management of infectious diseases” (p. 665).

Anderson , “Natural histories” (ref. 10).

Hadley (“Microbic dissociation” (ref. 70), 2), is rare in entertaining the possibility that behind “chaos” There may be only chaos.

Carter , Microbiology (ref. 13), 74–5 (italics mine).

Zinsser 9th edn (ref. 13), 126–9. In retrospect, it would be suggested that the bacteriologists themselves were getting habituated to a Lamarckian handling of phenomena which seemed a good deal more profound and challenging to those outside bacteriology or who came after. E.g.Tanner, Bacteriology (ref. 13), 45: ” These small single-celled microorganisms are quite likely to assume new characteristics when grown in the laboratory away from their natural habitat. New generations follow one another with great rapidity and new characteristics may be picked up quickly.” See Summers , “Culture as organism” (ref. 10); Kohler , “Innovation” (ref. 10), 178; Brock , Bacterial genetics (ref. 10).

Zinsser , 9th edn (ref. 13), 130. As Amsterdamska (“Stabilizing” (ref. 10)) points out, monomorphists found such cyclogenetic models deeply problematic, even though they were much closer to a monomorphic ordering of the world than was the earlier pleomorphism. See also Summers , “Culture as organism” (ref. 10).

Tanner , Bacteriology (ref. 13), 62–3.

Tanner , Bacteriology (ref. 13), 58; Carter , Microbiology (ref. 13), 74–5. See also Zinsser , 9th edn (ref. 13), 125.

While Nägeli had coined the term in contradistinction to evolution, one may well wonder whether its resonances drew also from “inversion”, the contemporary psychiatric term for homosexuality — One was concerned in both cases with deviance.

Tanner , Bacteriology (ref. 13), 58–9. Both are giving voice to Hadley's protest, quoted by Brock, Bacterial genetics (ref. 10), 26: “Under its [monomorphism's] influence … there were set up strict notions of ‘normal’ bacterial cell types, ‘normal’ colony forms, and ‘normal’ cultures. Whatever departed from the expected normality was at once relegated to the field of contaminations; or to the weird category of ‘involution forms’, ‘degeneration forms’, or pathological elements possessing neither viability, interest, nor significance….” Hadley (“Microbic dissociation” (ref. 70), 2) complained that that efforts to explain away variation in pursuit of taxonomic stability prevented important studies of its causes.

Zinsser , 9th edn (ref. 13), 125–6.

Zinsser , 9th edn (ref. 13), quoting Chick, 80. “Although geneticists would later realize that a pure culture is a clone and can therefore be thought of as a population of dividing and occasionally mutating cells, bacteriologists were generally incapable of thinking in terms of populations of cells” ( Brock , Bacterial genetics (ref. 10), 2; see also Summers , “Culture as organism” (ref. 10)).

Zinsser , 9th edn (ref. 13), 125.

Brock , Bacterial genetics (ref. 10), 26.

This scratches the surface. I have stressed identity here, but a broader focus on the relation of bacteriology to the germ theory of disease would highlight transformation in practices of causal attribution. I have hinted at, but not pursued, the remarkable moral status that bacteriology, and certain bacteriological practices acquired.

Latour Bruno , Science as action (Cambridge, MA, 1987).

Cf. the contrasting treatments of the work of Margery Stephenson by Brock , Bacterial genetics (ref. 10) and by Kohler, “Innovation” (ref. 10). “Another difficulty in the study of bacterial variability arises from the fact that bacteria, more than higher organisms, regulate enzyme synthesis in dramatic ways. The phenomena of enzyme induction and repression … are dramatically developed in bacteria, and lead to extensive physiological change when culture conditions are changed. Although these changes are phenomena of whole populations rather than of individuals, they confused many workers” (Brock, p. 46). Kohler (p. 179) complains: “After the discovery of bacterial genetics in the late 1940s, inducers of enzyme adaptation were seen as chemical messengers, not as participants in the chemical reactions of enzyme synthesis: Induction by substrates was a specific process unrelated to other varieties of adaptive behavior. In this new view, the complex phenomena that had seemed so promising to Stephenson were merely red herrings”.

Citing Lederberg's 1947 work, the Zinsser authors (Zinsser, 9th edn (ref. 13), 131) are intrigued by one unexpected version of gene exchange. “By growing deficient strains in symbiosis, new organisms were isolated which had the synthetic properties of both parent strains, suggesting that a fusion of two bacilli had occurred with an exchange of genes analogous to sexual fusion in higher forms”.

Other means contributed too. A survey of later textbooks suggests that the widespread availability of electron microscopy by the mid-1960s made it possible to characterize much more of the fine structure of bacteria, and put less stress on differentiation by cultural or chemical means.

Haraway Donna , Primate visions, gender, race, and nature in the world of modern science (New York, 1989); cf. Fleck , Genesis (ref. 1), 112.

Hamlin , Cholera (ref. 56), 258–78.

Reidl J. Klose K. , “Vibrio cholerae and cholera: Out of the water and into the host”, FEMS microbiology reviews, xxvi (2002), 125–39.