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Stud. Hist. Phil. Biol. & Biomed. Sci. 33 (2002) 733–750www.elsevier.com/locate/shpsc

Discussion

Ludwik Fleck and the causative agent of syphilis: sociology or pathology of science? A

rejoinder to Jean Lindenmann

Henk van den Belt

Wageningen University, Hollandseweg 1, 6706 KN Wageningen, The Netherlands

Received 19 September 2001; received in revised form 10 April 2002

Abstract

In 1905 two different microbes were proposed to fill the vacant role of etiologic agent for

syphilis, one, the Cytorrhyctes luis, by John Siegel, the other, Spirochaeta pallida, by FritzSchaudinn. After gathering and reviewing the evidence the majority of medical scientistsdecided in favor of Schaudinn’s candidate. In a previous issue Jean Lindenmann challengedLudwik Fleck’s suggestion that under suitable social conditions Siegel’s candidate could justas well have won acceptance by the scientific community (Lindenmann, 2001). To refute thiscounterfactual thesis, Lindenmann presented an asymmetric account of the dispute over theetiology of syphilis. He adopted the view of the proponents that Schaudinn’s spirochete hadalready been there in syphilitic lesions for centuries, only awaiting the discovery of an appro-priate staining technique to be revealed. Here a more symmetric analysis of the episode willbe attempted, paying serious attention to the arguments put forward by the spirochete’sopponents, who expatiated on the many possibilities of inadvertently creating artifacts through

microscopic preparation and staining. The symmetric account that is presented in this rejoinderthus aims to trace the simultaneous construction of facts and artifacts. It will not, however,resurrect Fleck’s counterfactual thesis.

© 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Treponema pallidum; Cytorrhyctes luis; Symmetry; Artifacts

Ludwik Fleck is widely recognized nowadays as an important forerunner of theconstructivist trend in the history, sociology and philosophy of science. The reception

E-mail address: [email protected] (H. van den Belt).

1369-8486/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.

PII: S 1 3 6 9 - 8 4 8 6 ( 0 2 ) 0 0 0 2 0 - 1

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734 H. van den Belt / Stud. Hist. Phil. Biol. & Biomed. Sci. 33 (2002) 733–750

of his book Entstehung und Entwicklung einer wissenschaftlichen Tatsache (Fleck,

1980) has been somewhat one-sided, however. Most commentators have fastened on

the conceptual and theoretical issues raised by this pioneering monograph. Only a

few have actually taken the trouble to examine the empirical adequacy of Fleck ’scase studies on syphilis and the Wassermann reaction which he used to demonstrate

his precocious constructivist approach (for a rare example, see Lowy, 1993). It is

more than welcome, therefore, that in a recent issue of this journal Jean Lindenmann

subjects Fleck ’s use of the dispute over the etiologic agent of syphilis to a detailed

critical scrutiny (Lindenmann, 2001). Admittedly, Fleck ’s discussion of this parti-cular episode is rather brief compared with his more extensive treatment of the devel-

opment of the Wassermann reaction; but what he has to say about it is indeed remark-

able and intriguing. Fleck suggests that under suitable social conditions John Siegel’s

Cytorrhyctes luis could have won acceptance by the scientific community as the

causative agent of syphilis instead of the real agent, Fritz Schaudinn’s Spirochaeta

pallida (now called Treponema pallidum). Both microbes had been proposed in 1905

to fill the vacancy for the etiology of syphilis. Lindenmann considers Fleck ’s sugges-

tion startling, if not outrageous. He also argues that the generally recognized etiologic

role of Treponema pallidum comes much closer to what is commonly understood

by a ‘scientific fact’ than the rather muddled relationship between the Wassermann

reaction and syphilis which Fleck chose as his prime subject. So if we want to do

a serious study of the genesis and development of a scientific fact, we should choose

the etiology rather than the serology of syphilis as our object of inquiry.

1. Lindenmann’s asymmetric account

A detailed examination of the dispute over the etiology of syphilis, however, does

not corroborate Fleck ’s view that it was social forces that decided the issue between

the adherents of John Siegel and Fritz Schaudinn and tipped the balance in favor of the latter’s Spirochaeta pallida. Or so Lindenmann maintains. He reviews a whole

set of social factors and concludes that each of them fails to discriminate between

the two competing groups. Lindenmann notably emphasizes that Siegel and Schaud-

inn had the same training (even with the same professor in ‘protozoology’, FranzEilhard Schulze), belonged to the same thought collective, shared the same thought

style1 and had full access to both material and financial resources. He reads a crucial

passage in Fleck ’s monograph as suggesting that Schaudinn’s spirochete won the

day due to rather minor social influences such as simple ‘public relations measures’

1 Lindenmann is rather emphatic in claiming that Siegel and Schaudinn belonged to the same thought

collective and shared the same thought style, but it is very doubtful whether Fleck would have agreed.

Lindenmann defines the allegedly relevant social forces in terms of ‘pre-existing’ factors that already

pertained to Siegel and Schaudinn before the controversy started. In Fleck ’s writings, however, a thought

collective and a thought style are often depicted as taking shape simultaneously with the new scientific

fact that is being developed. Fleck also would have considered it too ‘individualistic’ to define the relevant

social factors as attributes pertaining to concrete persons.

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735 H. van den Belt / Stud. Hist. Phil. Biol. & Biomed. Sci. 33 (2002) 733 – 750

(or ‘propagandistic gimmicks’): ‘If his [Siegel’s] findings had had the appropriate

influence [suggestive Wirkung] and received a proper measure of publicity through-

out the thought collective [denkkollektive Verbreitung], the concept of syphilis would

be different today . . .’ (Fleck, 1979, p. 39: cf. Fleck, 1980, p. 55).2 But in the givensituation, Lindenmann claims, such weak social forces could not possibly have

brought victory to Siegel’s microbe. For by mid-1906, at the time of Schaudinn’s

untimely death (June 22, 1906), medical scientists, at least those outside Germany,

were totally convinced that Schaudinn’s spirochete had already been there in syphil-

itic lesions for centuries, ‘that it had simply awaited being revealed for all to see bya reliable description based on an appropriate technique’ (Lindenmann, 2001, p. 449).

Nothing short of the exercise of brute force, of the order of Stalin’s notorious inter-

vention to compel Soviet geneticists into line with Lysenko, could have overwhelmed

this conviction.

In his eagerness to refute Fleck ’s views, Lindenmann thus ends up with presenting

a blatantly ‘asymmetric’ account of the dispute over the etiology of syphilis—not-

withstanding occasional but inconsequential qualifications. His historical reconstruc-

tion is colored by the present insight that Schaudinn’s pale spirochete, or Treponema

pallidum, is indeed the etiologic agent of syphilis. This retrospective wisdom allows

him to draw on the so-called empiricist repertoire (Gilbert & Mulkay, 1984) to

account for the actions of the non-German scientists who checked Schaudinn’s find-

ings. Ignoring German academic quarrels and pecking orders, ‘they simply got hold

of a good microscope and looked for themselves’ (Lindenmann, 2001, p. 448), nat-

urally confirming Schaudinn’s findings. (It is a little strange, though, that Lin-denmann disenfranchises the entire German scientific community: ‘The decision in

favor of Schaudinn was reached by the scientific community at large, outside Berlin,

outside Germany’—ibid., p. 448). To account for the actions of Siegel’s group, and

especially of Siegel himself, Lindenmann draws on the contrary contingent repertoire

(Gilbert & Mulkay, 1984), emphasizing irrational social and psychological factors:

‘the cytorrhyctes was born of delusion, ambition and incompetence’ (Lindenmann,2001, p. 449). Although Lindenmann does not say so explicitly, Siegel’s teacher

Franz Eilhard Schulze presumably sided with his former pupil out of the lifelong

loyalties forged in a student fraternity (Lindenmann, 2001, p. 438, n. 5). In his later

career Siegel is said to have exhibited all the telltale signs of a ‘scientific crank ’(ibid., p. 443). Thus his contributions are held up as a ‘clinical case study’ in ‘patho-

logical science’, a moral lesson for historians of science to ponder (ibid., p. 450).

2 The English translation seems not fully adequate to me. In the German original the sentence reads:

‘Ware seiner Erkenntnis entsprechende suggestive Wirkung und denkkollektive Verbreitung zu Teil

worden, so besaßen wir heute einen anderen Syphilisbegriff ’. The notion of ‘denkkollektive Verbreitung’

refers to how much extension an idea or finding receives within a thought collective, or to the size of

the thought collective that occupies itself with this idea or finding. This is not simply a matter of ‘publicity’

in the usual sense, let alone of ‘public relations measures’. Nor is ‘denkkollektive Verbreitung’ a minor

issue for Fleck; on the contrary, it is of central importance in his theory that lays so much stress on the

role of intellectual interaction (‘Gedankenverkehr’) in the formation of scientific facts!

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For Lindenmann, the sociology and history of science has become the pathology

of science.

The principle of symmetry, which is constitutive of modern constructivism, was

precisely formulated to counter the once widespread conviction among philosophersand historians that only ‘pathological’ episodes in the history of science (such as

the Lysenko affair in Soviet Russia or the Piltdown forgery in Britain) are amenable

to sociological analysis. As long as scientists followed the rules of the scientific

method, their behavior was held to be self-explanatory and there was considered to

be nothing to be explained by the sociologist; they would only become objects forsociological investigation if they deviated from those rules. The philosopher Newton-

Smith encapsulated this dominant approach in a nice formula: ‘sociology is for devi-

ants’ (Newton-Smith, 1981). The purpose of the principle of symmetry was to cut

through this prevalent asymmetry. Part of the interest of Fleck ’s pioneering work

resides in the fact that he can be seen as tentatively groping towards the modern

symmetry postulate. One ‘anticipation’ is cited by Lindenmann: ‘the social mech-

anism of the origination of an error is the same as that of the origination of true

knowledge’ (Fleck, 1986c, p. 123). Lindenmann concludes from this, too quickly I

think, that ‘social mechanisms cannot decide an issue’ (Lindenmann, 2001, p. 449).3

Fleck ’s criticism of the Durkheimian school in the sociology of knowledge, to the

effect that it failed to extricate itself from the belief that modern scientific thought

is beyond social conditioning (Fleck, 1986b, p. 80), anticipates similar criticisms by

modern constructivists.4 His insistent advocacy of a ‘non-egocentric’, comparative

epistemology (Fleck, 1979, p. 22) also points in the direction of the modern sym-metry principle.

The dispute over the etiology of syphilis seems a pre-eminent case calling for a

3 Lindenmann assumes without further argument that the resolution of an issue depends on unambigu-

ously establishing ‘truth’ and ‘error’. Moreover, with a little charity we could grant that the same types

of social mechanisms play a role in the origination of truth and error.4 In a footnote Lindenmann gives a rather special explication of the modern ‘postulate of symmetry’,

to the effect that different forms of knowledge (for example, western medicine and sorcery) should be

considered equivalent, and then concludes that there is ‘no indication that Fleck, who drew all his examples

from an observational and experimental tradition, would have endorsed this view’ (Lindenmann, 2001,p. 445, n. 14). We have an imbroglio of several misunderstandings here. It is simply not true that Fleck

only drew examples from the tradition of western experimental science, one objective of his theory being

‘to compare primitive, archaic, naive, and psychotic types of thinking and to investigate them uniformly’

(Fleck, 1979, p. 51). However, the modern postulate of symmetry is not a thesis about the substantive

equivalence of all the various forms of knowledge, but a methodological principle that enjoins the analyst

to treat the claims of the various parties to a scienti fic controversy in an impartial way. Depending on

the controversy under consideration, this postulate may on occasion necessitate the treatment of more

outlandish views as ‘equivalent’ in principle to more orthodox views, without regard to the personal

convictions of the analyst. In the main body of his text Lindenmann criticizes Fleck for limiting his

discussion to the two candidate microbes as possible causes of syphilis, without considering other conceiv-

able explanations such as masturbation, celestial punishment or sorcery (Lindenmann, 2001, p. 445). I

fail to see why this limitation should be considered a violation of the postulate of symmetry, as these

other conceivable explanations were not put forward by any of the parties to the controversy. Around

1900 the greater part of the medical community simply accepted the germ theory of contagious diseases.

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symmetric treatment in the modern constructivist sense. Fleck ’s discussion of this

episode is indeed symmetric in intent. The problem is that his treatment is just a

little too brief, only a cursory speculation and not a sustained symmetric analysis:

‘If his [Siegel’s] findings had had the appropriate influence and received a propermeasure of publicity throughout the thought collective, the concept of syphilis would

be different today. Some syphilis cases according to present-day nomenclature would

then perhaps be regarded as related to variola and other diseases caused by inclusion

bodies’ (Fleck, 1979, p. 39).5 Fleck abruptly ends his thought experiment, however,

by noting that ‘[a]lthough such a possibility could be envisioned logically and “objec-tively”, it can never be construed as a historical possibility’ (pp. 39–40). It thus

seems that Fleck only flirted with this idea, without taking it too seriously (at least

not as seriously as Lindenmann takes it). The reason why the counterfactual possi-

bility could not have become a real historical possibility, Fleck holds, is that by the

turn of the century the concept of syphilis had already become too rigid for Siegel’s

microbe to be accepted as the causative agent (Fleck, 1979, p. 40). It is remarkable

that Lindenmann pays no attention to this argument by which Fleck largely retracts

his counterfactual speculation.

Fleck ’s argument is not very plausible, however. It is doubtful whether the existing

syphilis concept really constituted the decisive obstacle for the acceptance of Siegel’s

microbe. Whereas Siegel postulated family relationships between his ‘agent of syph-

ilis’ and the purported causative agents of variola, cowpox, foot-and-mouth disease

and scarlet fever, Schaudinn in his turn construed a kinship relation between Spiro-

chaeta pallida and the causative agent of relapsing fever, to say nothing of the con-troversial connection with the trypanosomes (agents of tropical diseases such as

sleeping sickness) which he also suggested. To many medical doctors the array of

analogous diseases proposed by Siegel was actually more acceptable than Schaud-

inn’s list (for the pertinent judgement of an experienced dermatologist, see Lassar,

1905). So it is hardly likely that the existing concept of syphilis constituted the real

stumbling block for Cytorrhyctes luis.Having removed this obstacle for the execution of a sustained symmetric analysis,

we are faced with a more fundamental dif ficulty. It is arguable that Fleck, by simply

assuming in his thought experiment that Siegel’s findings ‘had received the proper

measure of publicity throughout the thought collective’, just begs the question andevades the main point, namely, to explain why Siegel’s microbe came nowhere near

the ‘measure of publicity’ (denkkollektive Verbreitung) that was achieved by Schaud-

inn’s agent. Why had the pale spirochete, only six months after its discovery, already

been found by more than a hundred investigators in various syphilitic lesions,whereas Siegel’s findings had been confirmed by only a few collaborators of the

Zoological Institute in Berlin, led by Professor Schulze? It would appear that such

preponderance in sheer numbers—which was bound to increase in subsequent

5 Siegel claimed that his alleged agent of syphilis, Cytorrhyctes luis, was related to what he considered

to be the agent of smallpox, Cytorrhyctes variolae, and to the purported agents of foot-and-mouth disease

and scarlet fever.

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months and years—constitutes a real challenge for a symmetric, constructivist expla-

nation. Would it not be natural to conclude that Schaudinn’s findings got so much

more confirmation because Treponema pallidum really is the agent of syphilis? In

other words, can we avoid lapsing into an asymmetric manner of accounting a la Lin-denmann?

2. Colored observation or the construction of facts and artifacts

Lindenmann suggests that medical investigators simply had to get hold of a good

microscope and look for themselves to be able to verify Schaudinn’s findings. But

microbiological observation is never that simple. You must already know more or

less what to expect in order to recognize something. This depends partly on the

availability of reliable descriptions in which the distinctive characteristics of the thing

to be seen are clearly set out. It also depends on the experience and competence of

the investigator, that is, on qualities that are notoriously dif ficult to define. Moreover,

in microbiology specimens are normally prepared in various ways to ensure or aug-

ment their visibility. They are cut into slices, fixed, stained, and so forth. This raises

additional problems. Does what we see through the microscope teach us something

about the living cell or the living microorganism, or only about the mutilations we

brought about by subjecting them to such a drastic preparation (to say nothing of

the possibility that the visible properties may also be caused by the microscopic

apparatus itself)? Due to the widespread use of staining, microscopic observation isquite literally colored observation, that is, colored in our own favor (Derksen, 1992,

p. 165). Microbiologists thus have to decide time and again whether or not they are

dealing with a so-called ‘artifact’ or spurious phenomenon. Some philosophers hold

that science disposes of readily applicable methods and criteria to tell fact from

artifact (Hacking, 1986; Franklin, 1989), but constructivists subscribe to the view

that the application of general standards in concrete cases always leaves room fornegotiation and contention. It would thus be possible, in conformity with the sym-

metry principle, to study simultaneously the construction of a fact and the

(de)construction of an artifact from a uniform perspective. For purposes of analysis,

then, facts and artifacts are to be put on a par and treated symmetrically.In the dispute over the etiology of syphilis the problem of colored observation,

and the possibility of creating artifacts through staining and other procedures, loomed

particularly large. Lindenmann only broaches such issues when he briefly mentions

the objections of Siegel’s friends to the staining and impregnation methods used tomake the pale spirochete (more) visible; but he does not follow up their arguments

and the ensuing debates in any detail (Lindenmann, 2001, p. 442, 443). I will take

up this task here in order to arrive at a more symmetric analysis of the dispute over

the etiology of syphilis.6 Despite Lindenmann’s claim that this dispute was decided

6 The following account is based in large part on Chapter IV of my unpublished thesis (Van den

Belt, 1997).

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by the scientific community outside Germany, I will concentrate on the discussion

within Germany. It was here, especially before the forum of the Berlin Medical

Society, that the two parties—the adherents and the opponents of Schaudinn’s spiro-

chete—went to great lengths to argue out their differences, each supporting theirclaims with microphotographs and demonstrations of stained and impregnated prep-

arations. Although they did not succeed in resolving any of the outstanding issues

that divided them (at least not to their mutual satisfaction), we may still note that

the German debate reached a ‘closure’ of sorts by the end of March 1907. From

that time on, the majority of the German medical community also accepted Spiro-

chaeta pallida as the true etiologic agent of syphilis.

Our account has to start, of course, at an earlier date. On 3 March 1905 Schaudinn

first discerned in a syphilitic papule freshly excised by his clinical collaborator, Erich

Hoffmann, a corkscrew-like microorganism of extreme transparence, which he recog-

nized as a spirochete. In the next weeks similar spirochetes were found in new patho-

logical material. Schaudinn and Hoffmann attempted to stain the spirochetes in fixed

preparations to improve their low visibility, and finally succeeded to some extent

with a so-called Giemsa solution (an eosin-azure mixture developed by G. Giemsa),

but only after staining for 24 hours. Because of this dif ficulty in staining, the microbe

received the baptismal name of Spirochaeta pallida or pale spirochete. Schaudinn

also thought that this species could be readily distinguished from other kinds of

spirochetes, in particular from a coarser type found in papillomas and balanitis, which

was dubbed Spirochaeta refringens. On 17 and 24 May 1905 Schaudinn and

Hoffmann presented their findings to the Berlin Medical Society, where they metwith the skeptical response described by Lindenmann. By that time they had already

received confirmation from Elie Metchnikoff in Paris, who, on Schaudinn’s request,

had searched for pale spirochetes in the syphilitic lesions of artificially infected apes

and monkeys (see Schaudinn’s letters to Metchnikoff, 2 and 8 May 1905, reprinted

in Zeiss, 1932, p. 173). Two German investigators, A. Buschke and W. Fischer, had

also found spirochetes in the liver and spleen of a stillborn syphilitic child. Theyhad their find authenticated by Schaudinn and Hoffmann: ‘A preparation was

immediately submitted for assessment to Messrs. Schaudinn and Hoffmann, who

declared that the spirochetes we found resemble those they found in morphological

and tinctorial respects’ (Buschke & Fischer, 1905, p. 792). At this stage replicationstill depended too much on personal contacts to be counted as truly independent con-

firmation.

About this time Schaudinn and Hoffmann were still very reticent to pronounce

on the etiologic status of the pale spirochete: ‘also today we are still far from passingalready a definitive judgement on the etiologic significance of this particular hitherto

unknown microbe’ (Schaudinn & Hoffmann, 1905, p. 675). Some have suggested

that this caution had been imposed by Schaudinn’s boss, the President of the Imperial

Health Of fice (Schuberg & Schlossberger, 1930, p. 583). However that may be, if

even Schaudinn and Hoffmann themselves were so cautious in their public claims,

the initial skepticism exhibited by their medical audience is hardly surprising. Thisskepticism was further enhanced by the active opposition from two staff members

of Professor Franz Eilhard Schulze’s Zoological Institute, Curt Thesing and Walter

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Schulze, who as supporters of the rival candidate for the etiology of syphilis did

everything they could to question the credentials of the pale spirochete. According

to Lindenmann, as already reported, Thesing ‘suggested that the spirochetes might

originate from the Giemsa stain used’ (Lindenmann, 2001, p. 442). At the first Berlinmeeting of 17 May, he showed photographs of object-glasses treated only with

Giemsa stain (without preparations from pathological material!), which exhibited

a certain resemblance to Schaudinn’s photographs of pale spirochetes. The latter’s

preparations, Thesing implied, might thus be no more than artifacts, representing an

instance of colored (or stained) observation. He also objected to the alleged protozoalnature of the pale spirochete; in his view, the preparations and photographs submitted

by Schaudinn would rather militate for its classification among the bacteria. In the

further course of the debate, the latter view would also come to be shared by several

proponents of the pale spirochete and thus no longer discriminate between the two

camps.7 A more serious matter was that the opponents also questioned the differen-

tiation between the pale spirochete and other species of spirochetes. Schaudinn had

pointed at the small size and delicacy, the number, steepness and rigidity of coils,

and the dif ficulty of staining as specific characteristics of Spirochaeta pallida dis-

tinguishing it from other spirochetes. He had even proclaimed: ‘If one has imprinted

the characteristic image of this spiral in one’s mind, then, in my opinion, one will

always easily recognize this form again’ (Schaudinn & Hoffmann, 1905). His

opponents called into question the very idea that there was a constant and character-

istic form of this putative species.

After the meetings of the Berlin Medical Society in May 1905, the credibility of the pale spirochete as a candidate etiologic agent of syphilis was rather low. It would

not take long, however, before the tables were turned in its favor. First, Thesing ’s

charge that Schaudinn’s spirochete might be no more than an artifact deriving from

the Giemsa stain used was effectively defused. In June 1905, this accusation aroused

an angry reaction from G. Giemsa, who claimed that Thesing must have handled

his stain in a very incompetent way. He expressed his conviction that the so-calledlikes of Schaudinn’s spirochetes shown by Thesing at the Berlin meeting were

7 The precise position occupied by the spirochetes within the system of nature has been a highly

contentious question. From a historical point of view, it is much more complicated than Lindenmannallows when he notes the irony that ‘the quintessential protozoologist’ Schaudinn ‘is best remembered

for his description of Treponema pallidum, a bacterium’ (Lindenmann, 2001, p. 444). For a long time,

protozoologists and bacteriologists have both ‘claimed’ the group of spirochetes (Davis, 1948). According

to some, ‘spirochetes represent[ed] a kind of no man’s land between the true bacteria and protozoa’

(Geiman, 1952). Modern textbooks tend to class the spirochetes (or the order of ‘Spirochaetales’) among

the Schizomycetes (bacteria in the broadest sense), but also to stress their special characteristics which

set them apart from the ‘true’ bacteria (for example, Cruickshank et al., 1973). Schaudinn’s classification

of spirochetes among the protozoa (protists) was also linked to his rather idiosyncratic view that malaria

parasites, trypanosomes and spirochetes were merely different forms in the development of one single

type of organism. In his presentation before the Berlin Medical Society, Schaudinn was rather reticent

about this peculiar theory, stressing that more research needed to be done. His theory, whatever its worth,

induced Paul Ehrlich, who attended the discussions before the Berlin Medical Society, to redirect his

chemotherapeutic research program from trypanosomal diseases to syphilis, which would ultimately lead

to the discovery of the ‘magic bullet’.

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nothing else than tiny crystals of methylene blue and methylene azure which had

precipitated during the drying of the Giemsa solution: ‘These [crystals] may, as any-

one can convince himself most easily, falsely suggest the most beautiful bacterial

flora, but they will be immediately resolved when the preparation is washed off withwater in the usual manner’ (Giemsa, 1905, p. 1027). Ironically, now it was Thesing’s

imitation spirochetes, designed to prove the artifactual nature of Schaudinn’s spiroch-

etes, which were to be exposed as artifacts!

During the next months, confirmations of Schaudinn’s and Hoffmann’s findings

continued to flow in. In the fall of 1905, Spirochaeta pallida clearly had the edgeover its rival, Cytorrhyctes luis. By October, spirochetes had already been found by

more than a hundred authors in the most diverse products of syphilis (Fleck, 1979,

p. 16; Lindenmann, 2001, p. 442). Such a large number carried weight and could

not fail to tip the balance in favor of the pale spirochete. Still the opposition,

organized from the Zoological Institute in Berlin, did not give in. The adherents of

Cytorrhyctes luis seized upon what seemed Spirochaeta pallida’s heel of Achilles:

its low visibility and, consequently, its dependence on artificial means of coloration.

When in late 1905 Giemsa staining was supplemented by the more powerful silver

impregnation method, the opponents of the pale spirochete did not hesitate to again

denounce the results obtained with the new method as artifacts. They thus opened

a second round in the debate on colored observation and artifacts. As Lindenmann

says, ‘Siegel’s friends . . . fought some valiant rearguard battles, concentrating on

demolishing the spirochaete, particularly when demonstrated by silver impregnation,

a notoriously tricky technique . . .’ (Lindenmann, 2001, p. 443). For the sake of asymmetric analysis, however, I believe that much more can and should be said about

these valiant battles, whether rearguard or not. Moreover, if Lindenmann agrees with

the spirochete’s critics that silver impregnation is ‘a notoriously tricky technique’,

then why does he not attach more weight to their arguments and objections?

3. Round two: the ‘silver spirochete’

So confirmatory findings came in from all sides. In October 1905 Schaudinn con-

fidently expressed his expectation that ‘[t]he findings will steadily increase evenfurther when all investigators acquire the necessary experience in finding and staining

these delicate forms’ (Schaudinn, 1905, p. 1665). Although he reiterated his view

that Spirochaeta pallida possessed a characteristic shape of its own which allowed

it to be clearly distinguished from other spirochetes, he also admitted that the recog-nition of this characteristic form required ‘a certain feeling for the typical’ (ein

gewisses Gefu hl fu r das Typische). Moreover, staining with Giemsa solution also

demanded experience and skill to avoid the occurrence of all kinds of artifacts

(Kunstprodukte). Schaudinn referred in particular to the hazard of insuf ficient stain-

ing, which would make other spirochetes appear just as pale as the pale spirochete

would be under normal staining conditions. This had already happened to a fewunlucky authors.

It was at about this time that two investigators, the Italian E. Bertarelli and the

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French-Romanian microbiologist Constantin Levaditi, independently of each other

developed a new method of staining (or rather impregnation) by means of silver

nitrate. Levaditi had been inspired by the silver impregnation method used by Santi-

ago Ramon y Cajal to demonstrate nervous tissue. The advantage of the silverimpregnation method was its capacity to show pale spirochetes regularly as black

spirals in tissue sections, whereas Giemsa staining was largely limited to the demon-

stration of those microbes in smears.

On 7 December 1905, at a meeting of physicians of the Charite hospital, Hoffmann

demonstrated several preparations of pale spirochetes obtained with the aid of thenew methods of Bertarelli and Levaditi. He made an important statement: ‘Finally,

I would like to emphasize on this occasion, that now, after so many authors have

furnished evidence for the specific nature of Spirochaeta pallida and the demon-

stration in tissue sections [Schnitten] also has succeeded, there can be no longer any

doubt about the etiologic significance of this organism’ (Gesellschaft der Charite-

Aerzte, 1905). Thus, by this time, Hoffmann was willing to drop all provisos and

reservations with regard to the etiologic status of the pale spirochete.

Thanks to the silver impregnation method, the stream of new finds of pale spiroch-

etes, in particular in tissue sections of internal organs, continued to flow during the

next year. Many medical authorities, such as Flugge, Gaffky and Loef fler, abandoned

their former skepticism with regard to the probable etiologic status of Spirochaeta

pallida. The pathological anatomist C. Benda later declared that the results of the

new method had made him completely change his mind in the period between March

and June 1906: from a ‘doubter’ ( Zweifler ) he had turned into a ‘confessor’( Bekenner ) (Benda, 1907).

After Schaudinn’s early death on 22 June 1906, the adherents of Cytorrhyctes luis

launched a full-scale attack on what they derisively called the ‘silver spirochete’, in

a last effort to stem the tide. They propounded the view that the preparations obtained

by silver impregnation were mere artifacts. Those black spirals made visible through

silver nitrate were not spirochetes at all, they maintained, but nerve endings, connec-tive tissue fibers, elastic fibers or other tissue constituents which had disintegrated

through tissue degeneration and subsequently taken on a spiral form as a consequence

of the alcoholic preservation and fixation treatment required by the silver impreg-

nation method. In September 1906, Walter Schulze reported about his attempts todemonstrate ‘silver spirochetes’, using Levaditi’s method, in the cornea of rabbits

inoculated only with street refuse. His article contained photographs showing the

‘silver pseudo-spirochetes’ thus obtained, which were said to closely resemble the

‘silver spirochetes’ obtained by Bertarelli and other investigators (Schulze, 1906).In the same issue of the Berliner klinische Wochenschrift , Schulze’s colleague Hans

Friedenthal presented photographs of silver precipitations in carcinoma tissue ‘which

bear a deceptive resemblance to the silver spirals described as Spirochaeta pallida’(Friedenthal, 1906, p. 1217). Likewise, a third member of the Zoological Institute

in Berlin, Theodor Saling, also contributed to what was apparently a concerted action

(Benda spoke about a Feldzug or ‘campaign’) to destroy the credibility of the ‘silverspirochete’. It is not dif ficult to imagine why they chose this as the strategic target

for their attacks, for as Saling concluded from the alleged exposure of this artifact:

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‘Therefore all those hundreds of confirmations, which allegedly prove the presence of

the so-called “lues spirochete” in the internal organs, have been dissolved’ (Berliner

medizinische Gesellschaft, 1907, p. 258).

The question of the ‘silver spirochete’ was put on the agenda of the Berlin MedicalSociety during four successive meetings on 20 and 27 February and 6 and 13 March

1907. In this ‘long debate between friends and opponents of the spirochete’—as

it was called by one of the participants, Alfred Blaschko (Berliner medizinische

Gesellschaft, 1907, p. 355)—almost all the issues which divided the two parties were

extensively discussed.8 The opposition party, represented by Saling, (Walter)Schulze, Friedenthal and Jancke,9 presented a coherent and tightly reasoned case. The

pale spirochetes that were mostly found in skin lesions and could be demonstrated in

smears through Giemsa stain had to be considered as harmless saprophytes, just like

some other spirochetes such as Spirochaeta refringens. Indeed, there was no set of

characteristics by which Spirochaeta pallida could be clearly distinguished from

other spirochetes and which would justify considering it as a separate species. The

fact that pale spirochetes were also occasionally found in syphilitic lesions revealed

nothing about their etiologic significance. As such the pale spirochetes stained with

Giemsa solution had nothing to do with the so-called ‘silver spirochetes’ demon-

strated in tissue sections by means of the silver impregnation method. The latter

represented nerve fibrils, elastic fibers or other normal tissue constituents which had

disintegrated through processes of tissue necrosis or maceration.

The adherents of Cytorrhyctes luis had several arguments to back up their assertion

about the non-identity of ‘Giemsa spirochetes’ and ‘silver spirochetes’. First, the twoclearly differed in appearance. The ‘silver spirochetes’ looked much shorter and

thicker. They did not accept Hoffmann’s explanation that the apparent shrinkage was

simply the combined effect of fixation and paraf fin preservation and the precipitation

of a coating of silver grains around the spirochete (Berliner medizinische Gesell-

schaft, 1907, p. 256). Secondly, Saling also pointed to the ‘enormous disproportion

which is manifested in the fact that in the same piece of tissue myriads of so-called

“spirochetes” are present after silver impregnation on sections, but that not a single

spirochete appears after staining with a true dyestuff!’ (Berliner medizinische Gesell-

schaft, 1907, p. 355). Such disproportion, he maintained, was not known of any other

bacterium or protozoon which could be stained both with dyes and with silver. Heformulated a methodological requirement which the adherents of Spirochaeta pallida

had to fulfil:

The identity of the ‘Giemsa spirochete’ with the so-called ‘silver spirochete’ canonly be made plausible if in sections of material treated in accordance with all

the rules of the histological art, precisely on the analogous sites where in the

sections impregnated with silver the so-called ‘silver spirochetes’ are located in

8 It is remarkable that Lindenmann does not pay attention to this particular debate.9 Franz Eilhard Schulze and John Siegel were conspicuously absent on both occasions (May 1905 and

February–March, 1907) when the Berlin Medical Society discussed the question of the spirochete.

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myriads, the same spiral fibers would also be demonstrated in equivalent quantities

by using a dyestuff. (Berliner medizinische Gesellschaft, 1907, p. 353)

This requirement of quantitative congruence is indeed rather demanding.During the meetings of the Berlin Medical Society in February and March 1907,

the ‘friends of the spirochete’ attempted to counter the criticisms put forward by the

opponents. They pointed out that ‘silver spirochetes’ had not only been demonstrated

in tissues but also in the lumen of blood and lymph vessels. Such findings, they

held, could not be explained by the tissue decay theory of the opponents.10 The latteranswered that on occasion fibers and other tissue constituents might be inadvertently

displaced from the tissue by the microtome knife (Berliner medizinische Gesellschaft,

1907, p. 350).

The pathological anatomist Orth was not impressed by the artificial ‘silver spiroch-

etes’ produced by the adherents of Cytorrhyctes luis. He could not hide his irritation

about their ways of arguing:

Hearing the opponents and reading their publications, one could believe that they

were dealing with scientific novices whom they had to teach the first principles

of microscopic observation. For my part, I have to protest when Mr Friedenthal,

for example, pretends that those black things which he showed in his pictures in

the Berliner klinische Wochenschrift . . ., are taken, or could be taken, for spiroch-

etes by competent investigators. No one would have hit on that idea. This is a

struggle against windmills. (Berliner medizinische Gesellschaft, 1907, p. 319)

Surely, not all the things that are stained black by Levaditi’s method are spirochetes,

Orth implied, but it could safely be entrusted to the critical judgement of the com-

petent investigators to distinguish artifacts from the real thing.

Two investigators, Hans Bab and Peter Muhlens, attempted to triangulate the etiol-

ogy with the emerging serology of syphilis. They pointed out that the findings of

‘silver spirochetes’ in the livers of syphilitic fetuses were confirmed by the outcomes

of the recently developed Wassermann reaction used for antigen determination of

‘liver extracts’ (Berliner medizinische Gesellschaft, 1907, pp. 259, 293). Saling

replied that the originators of this serological test themselves had declared that itwas not ready for practical use, as it did not yet furnish reliable results in every

case (Berliner medizinische Gesellschaft, 1907, p. 354). As we know from Fleck ’s

monograph, ‘antigen determination’ ( Antigennachweis) would later be abandoned

as spurious; ‘antibody determination’ would become the only reliable part of theWassermann test (Fleck, 1979, pp. 70–71).

To support the identity of the ‘silver spirochete’ and the ‘Giemsa spirochete’, the

pathological anatomist Benda showed photographs and preparations from the livers

10 This argument had already been used by Levaditi in a first reaction to Walter Schulze’s accusations

(Levaditi, 1906).

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of syphilitic children. Smears taken from the same material which in silver-impreg-

nated tissue sections exhibited the presence of ‘silver spirochetes’ showed pale spiro-

chetes after staining with a Giemsa solution (Berliner medizinische Gesellschaft,

1907, pp. 293, 357). This was obviously intended to answer the methodological

demand for congruence. The opposite party, in the person of Saling, reacted by

denying that the spirochetes stained with Giemsa belonged to the species Spirochaeta

pallida; they were said to exhibit the species characteristics of Spirochaeta refringens

(Berliner medizinische Wochenschrift, 1907, pp. 293, 356). To Benda this assertion

was ‘completely at odds with the fact’ (durchaus der Tatsache widersprechend ). The

venereologist Alfred Blaschko commented on this disagreement: ‘In my view, the

preparations of Mr Benda are not conclusive to a malevolent judge, but only to those

who have any inkling of the extreme dif ficulty with which these organisms can be

stained with Giemsa’ (Berliner medizinische Gesellschaft, 1907, p. 356; emphasisadded). Blaschko also argued that the methodological requirement of a complete

congruence, even in quantitative terms, between the results of silver impregnation

and Giemsa staining was highly unreasonable. Given its delicacy and its special

tinctorial properties, it was no more than to be expected that Spirochaeta pallida

could not be made visible with the normal dyes in the relatively thick tissue sections.

During the long discussions within the Berlin Medical Society, many ‘friends of

the spirochete’ must have had the feeling that in dealing with their opponents from

the Zoological Institute they were rapidly reaching the limits of reasonable debate.

Their exasperating experience was that they could not force their opponents into

line by what they considered rational and convincing arguments. Their determinedopponents acted much like ‘Awkward Student’ or ‘the obstinate dissenter’ in modern

sociology of science textbooks (Collins, 1985; Latour, 1987). No wonder that the

‘friends of the spirochete’ sometimes resorted to authority arguments. Both

Hoffmann and Orth, for example, disputed the competence of non-medical scientists

to speak about medical subjects such as necrosis and maceration. Hoffmann also

emphasized that ‘virtually all syphilologists’ and ‘almost all pathological anatomists’supported the etiologic status of Spirochaeta pallida (Berliner medizinische Gesell-

schaft, 1907, p. 256).

As will probably be clear by now, the controversy about the ‘silver spirochete’was not settled. In his final word Saling reaf firmed his position: ‘All those hundreds

of “confirmers” (“ Besta tiger ”) have fallen victim to a severe delusion; and Mssrs.

Bertarelli, Hoffmann, Benda and their likes may not take it ill of me that I have some

doubts about their critical judgement and their capacity of observation’. Blaschko, in

his final speech, noted that all rational arguments had been idle and impotent: ‘Who

does not want to be convinced by what Mr Benda and I, and by what Mssrs. Mu hlens,

Hoffmann, Bab and others have expounded in truly suf ficient extension, such a per-

son cannot be convinced in any possible way’ (Berliner medizinische Gesellschaft,

1907, pp. 355, 356). Blaschko concluded that it was time to close the debate and to

continue the work on the Spirochaeta pallida without regard for the views of theobstinate opponents. And this is indeed what would happen: from then on, the

opponents’ criticisms would be simply ignored.

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4. Discussion and conclusions

In the dispute over the etiology of syphilis, the ‘construction of a fact’ (i.e. the

fact that Treponema pallidum is the etiologic agent of syphilis) was intimately con-nected with the question of the possible creation of ‘artifacts’. Seen from the perspec-

tive of the minority group of ‘opponents of the pale spirochete’ the same episode

should rather be described as the failed deconstruction of an artifact—’failed’ in the

sense that the opponents were unable to persuade the larger medical community of

their views. According to realist philosophers such as Ian Hacking or Allan Franklin,science has available several ready-made methodological criteria by which to dis-

tinguish genuine results from mere artifacts. One possibility is to use the ‘argument

from coincidence’ by obtaining the same result using different experimental appar-

atus or procedures. Hacking gives the example of seeing dense bodies in cells by

the use of both electron and light microscopes: ‘I say that if you can see the same

fundamental features of structure using several different physical systems, you have

excellent reason for saying, “that’s real” rather than, “that’s an artifact”’ (Hacking,

1986, p. 204). In this article we have seen that two different staining methods,

Giemsa staining and silver impregnation, were deployed to visualize the pale spiroch-

ete. This could not, however, resolve the issue at stake.

For the ‘friends of the spirochete’ the matter was clear: silver impregnation con-

firmed the results obtained by Giemsa staining and substantially enlarged the field

of visibility of the microbe. The ‘opponents’, however, saw things differently. They

stressed the dissimilar appearances of the ‘Giemsa spirochete’ and the ‘silver spiroch-ete’, discounting the explanation given by the other side for this difference. They

also pointed to the great discrepancy in numbers of spirochetes detected in similar

tissues by using the two staining methods, thus arguing that there was no congruence

in quantitative terms between the results of both methods. Of course, for the ‘friends’such lack of exact quantitative correspondence was precisely what was to be

expected, given the character of the spirochete (its dif ficult stainability with Giemsadye). In the present case, then, the issue at stake—genuine result or artifact?—could

not be settled to the satisfaction of the opposing parties by the deployment of differ-

ent staining methods, because there was no agreement on what constituted compara-

ble outcomes or suf ficient congruence. The situation is similar to what Harry Collinshas described as the ‘experimenters’ regress’ (Collins, 1985).

Nor could an appeal to the large number of independent confirmations of Schaud-

inn’s and Hoffmann’s findings settle the matter. The charge that the ‘silver spiroch-

ete’ was a mere artifact was aimed precisely at destroying the credibility of thegreater part of those confirmations. In the end the controversy over the etiology of

syphilis was ‘closed’ by ignoring rather than painstakingly refuting the detailed

objections of the minority group of ‘opponents’. As this group was able to invent

new criticisms after each attempt of refutation, it appears that this was the only way

to achieve ‘closure’. In Collins’ terms: some way to break the circle of the exper-

imenters’ regress had to be found.A notable fact about the entire episode is that Schaudinn’s spirochete was eventu-

ally accepted in medical circles as the causative agent of syphilis even if Koch’s

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postulates (which require that a pure culture of the suspected microbe has to be

inoculated in a susceptible animal to see if it causes the disease) remained unful filled.

The pale spirochete stubbornly resisted every attempt at cultivation in nutrient media.

It is interesting to note that initially many medical specialists suspended a definitive judgement until Koch’s rules would be met. Lindenmann refers to the outcome of

a sort of poll among European dermatologists in the fall of 1905: ‘all were in favor

of the spirochaete, although most insisted that definitive proof along the principles

laid out by Koch was still lacking’ (Lindenmann, 2001, p. 442). The ‘definitive

proof ’ would never be produced, but eventually the etiologic role of the pale spiroch-ete would be accepted even in the absence of this crowning piece of evidence. The

etiology of syphilis is not the only exception in the history of medical microbiology.

So it appears that even such basic rules of the game as Koch’s postulates are ‘nego-

tiable’ after all, as constructivists would have expected all along (cf. Bloor, 1999,

pp. 102–103).

Another salient feature of the debate on which I may have put too little emphasis

was the wide variability of the descriptions. Particularly in the initial stages, the

series of characteristics attributed to the pale spirochete varied almost from one publi-

cation to the next. Critics did not hesitate to capitalize on these apparent inconsist-

encies to throw doubt on the very existence of the microorganism (for some strongly

sarcastic comments, see Friedenthal, 1906). Fleck was well aware of this phenom-

enon in a different area of microbiology, as his analysis of the changing descriptions

of diphtheria bacilli in successive bacteriological textbooks testifies (Fleck, 1986a).

Elsewhere, he describes the emergence of a common Gestalt or standard pattern asarising out of the ‘oscillating pictures’ and ‘fantastic images’ proposed by individual

investigators: ‘[T]he collective life produces among these oscillating possibilities a

novel prescribed form, which is then fixed and pressed upon the individual. The

collective experience and custom determine which feature is fundamental and what

can be variable, and how far this variability can extend’ (Fleck, 1986d, p. 140).

Something similar has happened in the collective process of learning about thecharacteristics of the etiologic agent of syphilis. Fleck ’s views on human perception

and scientific observation are still pertinent and useful for historians of science.

In this article, answering the challenge posed by Lindenmann’s asymmetric

account of the dispute over the etiology of syphilis (Lindenmann, 2001), I have triedto present a more symmetric analysis of the same episode. Following the symmetry

principle, however, does not imply endorsement of the rather implausible counterfac-

tual thesis that Siegel’s Cytorrhyctus luis could ‘ just as well’ have won acceptance

as the causative agent of syphilis as Schaudinn’s Spirochaeta pallida. If Siegel’sallies were able to mount an impressive array of objections against the etiologic

status of the pale spirochete, thus undermining the latter’s credibility, they did not

succeed in bringing their own favored candidate back into the race as a serious

contender. One might speculate to attribute this different success to differences in

the two thought collectives involved. While the (non-medical) Zoological Institute

in Berlin acted as Siegel’s bulwark, from the very outset the Schaudinn-Hoffmanngroup had better access to the of ficial medical world through Hoffmann’s principal,

Professor Edmund Lesser at the Dermatological Clinic of the Charite Hospital in

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Berlin. Although this may have been an important asset in their attempts to convince

the German medical community, I also think that we should not make too much of

this difference. An explanation in terms of such straightforward structural differences

between thought collectives does not take us very far in this particular case. I havetherefore chosen to follow the debate on the etiology of syphilis as it unfolded,

paying ‘symmetric’ attention to the arguments of both the ‘friends’ and the

‘opponents’ of the pale spirochete. This allowed me to perform a simultaneous analy-

sis of the construction of facts and artifacts during the same episode.

But what about the standard accusation that constructivist analyses do not allowthe drawing of a distinction between facts and artifacts, or even worse, that they

effectively degrade all facts to artifacts (Bunge, 1992; Nola, 1994)? If facts are mere

(social) constructions, then in what respect do they differ from artifacts? My personal

reply to this charge is to concede that there is indeed a meaningful distinction to be

drawn between facts and artifacts. However, I reject the claim that it is the duty of

the analyst of science to tell fact from artifact in concrete cases (that is the job of

the scientists themselves) or even to provide general standards and criteria by which

this distinction can be made in actual scientific practice. It is true that some philos-

ophers of science (for example, Allan Franklin) have proposed such standards and

criteria, but I already pointed out that the application of these standards usually

leaves considerable scope for indeterminacy. In addition to the present case study

on the etiology of syphilis I can also refer to Nicolas Rasmussen’s excellent historical

study of the so-called ‘mesosomes’ for a telling example (Rasmussen, 1993). It took

about 15 years before these purported cell structures, identified during the 1950swith the aid of the new electron microscope, were called into question as being mere

artifacts (although even now there are still researchers who are convinced of their

factual status!). This long period militates against the idea that science disposes of

readily applicable criteria for telling fact from artifact. Rasmussen also shows in

detail that researchers often disagreed about the relative importance of the various

criteria that could be brought to bear on the issue; and even where they agreed onthe principles to be applied, they disagreed about their concrete application! It would

thus seem that there is indeed wide scope for a constructivist analysis to handle the

construction of facts and the (de)construction of artifacts in an evenhanded way using

a single analytical framework. This is precisely what I attempted to do in this article.The possibility of such an analysis is a direct corollary of the symmetry principle.

For purposes of analysis, facts and artifacts are put on a par and treated symmetri-

cally, but this does not mean that the former are transformed into the latter.

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