Isolation, Contamination, and Pure Culture: Monomorphism and Polymorphism of Pathogenic Micro- Organisms as Research Problem 1860–1880 Downloaded from http://direct.mit.edu/posc/article-pdf/9/2/147/1790560/106361401317447264.pdf by guest on 25 September 2021 Christoph Gradmann University of Heidelberg This article analyzes German debates on the microbiology of infectious dis- eases from 1865 to 1875 and asks howand whenorganic pollution in tis - sues became noteworthy for aetiology and pathogenesis. It was with Ernst Hallier’s pleomorphistic microbiology that the organic character of alien ma- terial 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 speciªcity, etc. fa- vored by Ferdinand Julius Cohn and his school became popular in medical circles. A Science of Purity and Contamination The rise of medical bacteriology with its concept of pathogenic germs as causal agents of diseases is commonly held to be one of the fundamental changes occurring in nineteenth century medicine.1 The notion that par- ticular infectious diseases are caused by particular pathogenic microbes whose presence or absence almost deªnes such diseases seems a common- place. Even if the knowledge of the existence of bacteria can only be at- tained by experts who themselves have to rely on necessary technology I thank Sarah Jansen (Cambridge, Mass.) for translating nineteenth Century German bo- tanical terminology and Alexandre Métraux (Dossenheim) for a critical reading. 1. For an introduction see: Gradmann and Schlich (1999); Tomes and Warner (1997); Worboys (2000). On the peculiarities of the bacteriological understanding of diseases: Cunningham (1992); Carter (1985); Schlich (1999). Perspectives on Science 2000, vol. 9, no. 2 ©2002 by The Massachusetts Institute of Technology 147 148 Isolation, Contamination, and Pure Culture everybody takes their existence for granted and agrees that isolation, cleanliness, and disinfection are appropriate ways to deal with such dan- gerous intruders (Gradmann 2000b; Kraut 1994; Martin 1994; Tomes 1998). That man’s relations to microbes are of an antagonistic sort is a commonly shared view and we even try to avoid getting in touch with bacteria by hygienic measures—despite the fact that this is not a very promising endeavor given their invisibility (cf. Canetti [1960] 1984, Downloaded from http://direct.mit.edu/posc/article-pdf/9/2/147/1790560/106361401317447264.pdf by guest on 25 September 2021 p. 47). The aim of this article is to shed some light on the development of some central notions of this concept of pathogenic germs which cause dis- eases and in whose control we tend to see an angle to ªght diseases (Schlich 1999). When and how did notions such as puriªcation, contami- nation, and isolation which contain, as a recent historian of AIDS noted, “the mission of biomedicine in a nutshell” (Epstein 1996, p. 31) acquire their speciªcally bacteriological semantics and their the enormous impor- tance for medical bacteriology? In a broad sense the genesis of the concept of pathogenic germs can be placed into the history of the nineteenth century. It was in this period when a healthy and clean human body became re-deªned as germ-free body and when the threats posed to it by an outside world appeared in the new form of dangerous bacteria.2 Aided by hygiene, anti-sepsis etc. men attempted to ªght off diseases and their embodiments, bacteria. The new relation of men and microbes became part of societies, when “the hygien- ists introduced the notion of a microbe as the essential cause of infectious disease, they did not take the society to be made up of rich and poor, but of a rather different list of groups: sick contagious people, healthy but dangerous carriers of microbes, immunized people, vaccinated people and so on” (Latour and Woolgar 1987, p. 116). Microbes became pathogens in the late nineteenth century and the semantics of their antagonistic rela- tionship to men has turned out to be a remarkably stable cultural pattern of our time (Kraut 1994; Martin 1994). This rise of this popular bacteriology has to be seen in intimate connec- tion to the history of the science of medical bacteriology, on which this pa- per will focus. From the 1860s, on microbiology and pathology came to be related in a way that helped to envision invisible microbes as embodi- ments of diseases and to create the above mentioned notions: to see bacte- ria inside organisms as contamination, to foster the idea of a human body that needed to be kept free from pathogenic germs which in turn needed 2. On popular bacteriology see Gradmann (2000b); Kraut (1994); Martin (1994); Tomes (1998); Brecht and Nikolow (2000); Vigarello (1988); Lachmund and Stollberg (1995, pp. 186–92). Perspectives on Science 149 to be isolated and controlled. Just as hygienic medicalization of societies meant that contemporaries had to adapt to new patterns of perception and behavior, medical bacteriology grounded itself in a novel understanding of the microcosm and its inhabitants which was now considered to be caus- ally responsible for aetiology and pathogenesis of infectious diseases.3 In the process of establishing that order, scientiªc concepts and tech- nologies of purity and contamination such as bacterial speciªcity, pure Downloaded from http://direct.mit.edu/posc/article-pdf/9/2/147/1790560/106361401317447264.pdf by guest on 25 September 2021 cultures or disinfecting, acquired a high importance. The image of ‘classi- cal’ medical bacteriology such as devised by Robert Koch and his school is closely related to technologies like bacterial staining, pure cultures, mi- cro-photography, or solid culture media, and on the theoretical level found its most veritable icon in the famous postulates that had to be fulªlled to establish bacterial aetiologies.4 The enormous accent that Koch and other medical bacteriologists put on bacterial speciªcity, isolation, and puri- ªcation is usually explained by contrasting their achievements with con- temporary German and French research. Koch’s accent on technologies and concepts safeguarding speciªcity and stability of bacterial species ap- pears as an attempt to establish his school of bacteriology by contrasting it with other microbiological research such as Pasteur’s theory of bacterial virulence, Naegeli’s bacterial transformism or Pettenkofer’s localistic the- ory of infectious diseases.5 Even if the contrast with Pasteur, Naegeli, or Pettenkofer helps to un- derstand the peculiarities of Koch’s emphasis on stability and speciªcity of bacterial species, one might also ask how Koch’s conceptions related to on- going contemporary discussions on the microbiology of infectious diseases in Germany. This issue had been a heatedly discussed topic in Germany from about 1865 on and it is remarkable to see how contemporaries ini- tially succeeded in discussing the microbiology of infectious disease with- out employing notions of purity and contamination (Diepgen 1926; Faber 1930, pp. 95–94). It was rather—as this paper will demonstrate—that the discussions started with the discovery of manifold organic pollution in the intestine of cholera-victims or in septic wounds. What followed from ca. 1865–1875 was a process of conceptual and experimental speciªcation and puriªcation of such ‘vegetation’. The result was a reductionist model of the aetiology of infectious disease, and most of the earlier experimental 3. On the history of bacteriology see Bulloch ([1938] 1960); on medical bacteriology see Foster (1970); Worboys (2000); See also Mendelsohn (1996). 4. On Koch and his school see Gradmann (2001, encyclopaedia article). On the devel- opment of his school in particular see Mazumdar (1995); Mendelsohn (1996); Weindling (2000). On Koch’s postulates see Carter (1985); Schlich (1997). 5. On Pasteur see Geison (1995); Mendelsohn (1996); on Naegeli see Mazumdar (1995); on Pettenkofer: Hubenstorf (1993); Jahn (1994). 150 Isolation, Contamination, and Pure Culture work came to be regarded as technically inadequate, e.g., working with mixed cultures, using inefªcient technologies of isolation and so forth.6 However, initially such research gave plausible answers to the microbiol- ogy of infectious diseases and we may well ask how experimental evidence for pathogenicity was produced, which role questions of purity and con- tamination played in this context, how they entered the debates, and how this adds to our knowledge about the early days of medical bacteriology. Downloaded from http://direct.mit.edu/posc/article-pdf/9/2/147/1790560/106361401317447264.pdf by guest on 25 September 2021 Classification and Transformation Even though the existence of a microcosm of microbial life was well known to contemporaries and research on the nature of lower organisms was extended, disagreement on the nature and order of microbial life was fundamental in mid nineteenth century (Jahn 1990, pp. 351–364). The idea that these organisms could be sorted into distinct and constant spe- cies was—all in all—a minority opinion. Its most prominent spokesman around 1860 was Ferdinand Julius Cohn, a botanist from Breslau. He had developed a taxonomical system of bacteria which he clearly separated from microscopic fungi or algae and distinguished four basic types that could be subdivided on the basis of morphology.7 However, such system- atic aspirations were far from being uncontested: Cohn’s constant bacterial species could easily be contrasted with opposing observations where one form could turn into another (transformation) or appear in diverse forms (pleomorphism). Apart from this, smaller structures that could be ob- served through a microscope simply appeared as pellets or granules that withstood any attempt to make distinctions.