Beyond retouching: Hans Virchow’s mixed media and his X-ray drawings of the lotus foot

Vera Dunkel

In late December 1895, Wilhelm Conrad Röntgen publicized his discovery of invisible rays and his invention of a new photographic technique that allowed him to record the interior of opaque and solid bodies in pictures.¹ One of the first of Röntgen’s readers in Berlin to respond to this announcement was Hans Virchow. On January 12, 1896, he wrote to the professor in Würzburg to request a copy of a picture that had quickly become famous: an X-ray image of the hand of Röntgen’s wife, Bertha.²

An anatomist and anthropologist who worked as prosector at the Charité hospital in Berlin, Virchow studied the mechanics of movement in the living organism. Röntgen’s procedure was obviously of interest to him, since it promised to allow him to examine the positions of bones in the living body. We don’t know whether Röntgen ever complied with his request. What is certain is that Virchow soon used radiography in his research, as the studies he produced between 1899 and 1911 on the musculoskeletal system of the hand attest. Yet he also quickly became aware of the new imaging technique’s peculiarities and took a skeptical view of its visualization capacity and epistemic potential. For example, he once complained that what the pictures showed didn’t always match the “reality”.³

In order to take an X-ray image, the object to be examined—in this instance, the hand—is placed between the radiation source and the visual medium, a light-sensitive photographic layer. When voltage is applied to a vacuum tube, it emits the shortwave radiation that Röntgen labeled X-rays. Invisible in themselves, the rays penetrate parts of the object, darkening the photographic plate: the “shadows” of more solid parts of the object emerge as white silhouettes. The object’s opacity to the X-ray beam varies with the thickness, density, and composition of its parts; in the human hand, for example, bones are relatively impermeable while soft tissues such as muscles and sinews allow most of the radiation to pass through.

Yet the appearance of the resulting negative image depends not only on the object’s inherent properties, but also on how it is positioned relative to the photographic medium as well as on its distance from the radiation source and the orientation of the latter. According to the geometry of projection, changes in the arrangement of these elements can lead to variations in the shapes of the shadows; distances between the bones—Virchow’s particular focus of interest—appear now larger, now smaller, and the bones themselves are depicted with greater or lesser distortion. Moreover, the images of the individual bones in the hand tend to overlap, especially in lateral radiographs. The gray tones add up, so as to merge, making it difficult to distinguish the various elements. Another problem that vexed scientists, especially in the early years of radiography, was the need to keep the living body rigidly fixed for as long as several minutes, to prevent any blurring of the image.

So the divergence that Hans Virchow pointed out, between the object under examination and its radiographic depiction, results on the one hand from the specific characteristics of an imaging technique that records projected shadows and, moreover, translates density, a variable that is in and of itself invisible, into shades of gray, and, on the other hand, from possible deviations of the final image from the “reality”, as Virchow put it, owing to physical and technical factors in the experimental set-up.

Virchow was keenly aware of these issues because he always relied on multiple methods of examination. For example, comparing X-ray images with his manual drawings as well as with prepared specimens revealed the problems of radiography. In his work on the motor system of the hand, the first research for which he relied in part on radiographs, Virchow repeatedly emphasized the need to integrate multiple methods in order to arrive at an adequate representation and understanding of the object.

In the present chapter, I first survey the media that Virchow used. In a second step, I illustrate how these media interacted in his work, and try to draw a distinction between mixed media and fused media. That brings me to my third point: a discussion of the epistemic status that radiographs—as photographic images, which is to say, instrumentally generated pictures—have in this context. I intend to demonstrate how Virchow’s reflections helped him rebuff the charge of subjectivism. He eventually framed a fundamental critique of technical imagery in which subjectivity emerged as a crucial prerequisite of scientific insight.

Mixed media: combining media

In his very first treatise on the motor system of the hand after he started working with radiographs, Virchow discusses the use of multiple media and their epistemic value for the study of his object. He concludes: “To get a clear picture of the object, I needed to make analytical drawings in which I used different colors; and the frozen skeleton specimens were a crucial aid in interpreting what I saw”.⁴ His subsequent publications likewise show that he always considered “flat images”, such as photographs and radiographs, side by side with three-dimensional anatomical specimens, and untiringly consolidated his findings in vivid illustrative drawings. Two techniques were fundamental to Virchow’s studies.

The frozen skeletons he mentioned were body parts that had been arranged in a specific posture as quickly as possible after the donor’s death and then frozen. In order to examine particular details concerning the relative positions of the bones, Virchow took a cast of the limb, then removed the viscera piece by piece, on one side, and took a second cast. Finally, he reassembled the bones with the aid of the casts to construct a faithful recreation of the original relations between the parts. He called this procedure “skeleton assembly according to form” (Skelettverfahren nach Form); even before the introduction of radiography, he had used the results as a visual aid in anatomy classes for artists.⁵

A second technique Virchow was already using before Rontgen’s discovery was the so-called “salt-paper process”: he made prints from photographic negatives on salt paper, drew over them, and then washed out the print. The photograph disappeared, but the drawing remained—and he sometimes then further enhanced it, also by adding color.⁶ This second technique is already a hybrid that blends multiple media: the

Beyond retouching 81 technical (photographic) image serves as the point of departure or basis for the manual execution of a drawing that incorporates the scientific knowledge Virchow has gained of the object, hence his term “analytical drawing”.

Virchow builds on this technique by combining it with the prepared skeleton specimens; for example, he takes several photographs of a specimen showing different bone parts or bones in different positions, superimposing the images by means of multiple exposures or tracing the outlines of bones in the different proofs to obtain a composite depiction (Figure 6.1). This image shows the metacarpal bones in their natural relative positions in a lateral view. In extracting the essential features from multiple partial views, the composite drawing lucidly represents that which would appear, in a simple radiograph, as a “confusing tangle of lines”. In closing his study, Virchow notes: “This approach enables us to bring the confusion of lines under control in the progress of analysis”.⁷

Virchow considers at length the advantages and drawbacks of both techniques. Radiography, he writes, produces “twilit images” that are “moreover fraught with a number of potential sources of error”; the reconstructed skeleton, by contrast, presents “the object itself in its three-dimensional reality” and “may be turned this way and that way and inspected from all sides”. On the other hand, the skeleton technique requires much more time and effort, and the use of cadaver material, whereas X-ray images are quickly and easily obtained from living bodies. “I am persuaded that we stand to benefit from a prudent assessment of the merits and shortcomings of both methods and their mutual critique of each other”.⁸ As Virchow sees it, the solution

„X

Abb. 4.

Die fünf lletakarpalien eines linken nach dem Formverfahren behandelten Handskeletts, aus Einzelaufnabmen zusammengepaust.

Figure 6.1 Hans Virchow, composite drawing of the metacarpal bones of the hand in a lateral view, 1911. Source: Hans Virchow, “Das Verhalten des Navikulare Medizinische Klinik 7, no. 24: 932. Staatsbibliothek zu Berlin—Preußischer Kulturbesitz.

is to be found in a combination of techniques. He makes clear that no single method is sufficient for the study of the movements of individual bones within the body, and that each technique requires the aid of the other to shed light on the object.

Different techniques complement one another in that one reveals what the other cannot show. But they may also enter into a veritable fusion, as when Virchow makes a double exposure, superimposing a photograph and a radiograph of the same object “in order to obtain an image that combines the transparency of radiography with the lifelikeness of photography”.⁹ What makes such fusions especially interesting is how the resulting images blend the characteristic aesthetics of various techniques.

Fused media: X-ray and ink drawings

One instance of such fusion appears in another field of research to which Virchow devoted particular energy: the artificially deformed feet of Chinese women, which nineteenth-century Europeans regarded as an ethnological curiosity. Virchow’s interest in the phenomenon grew out of his studies in developmental anatomy; he saw it as a prominent example of how “a part of the human body, and in particular its bones, can adapt to changed conditions”.¹⁰

In an article published in 1903, he describes the varieties of “morphological alteration”: bending, squashing, and atrophying.¹¹ The accompanying illustrations are drawings derived from photographs of prepared bone specimens by way of the salt-paper process (Figure 6.2).

Figure 6.2 Artificially deformed bones of the foot compared with normal ones, 1903. Source: Hans Virchow, "Das Skelett eines verkrüppelten Chinesinnen-Fusses”, Zeitschrift für Ethnologie 35, plate 7. Staatsbibliothek zu Berlin—Preußischer Kulturbesitz.

Each deformed bone is paired with a “normal” specimen for comparison. The drawings are impressively lucid and graphic; it is almost as though the original specimens were rising from the paper before the reader’s eye. The outlines of the bones and the anatomist’s labels, printed on transparent paper (on the right), may be superimposed on the drawings.

In 1905, Virchow was provided with new materials, including radiographs from three women of different ages, which led him to write a second article on the subject.¹² It is accompanied by a very different kind of imagery. The first plate shows three different photographic views of a plaster cast of a 30-year-old individual’s foot; three further plates depict the feet of a 10-year-old girl, and of two women aged 24 and 32, respectively (Figure 6.3).

The casual viewer probably assumes that these pictures are radiographs. The crystalline clarity with which the bones are silhouetted amid the shadow of the living body’s viscera is stunning. Despite the overlapping due to the lateral view, each appears as a distinct object, tangible and translucent at once; all elements of the foot’s skeleton can be clearly identified.

As the text reveals, these images are retouched copies of the X-rays Virchow had been given. Fortunately, some of his visual materials have survived at the Anatomical Institute of the Charité in Berlin, so we can gain an idea of how he proceeded.

Starting with the radiographs (Figure 6.4)—this one shows both feet of the 32-year-old woman, captured, it is easy to see, in a recumbent position—Virchow made drawings using the salt-paper method, carefully tracing each bone (Figure 6.5). In order to

Figure 6.3 Retouched X-ray of the foot of a 32-year-old woman, 1905. Source: Hans Virchow, “Weitere Mitteilungen über Füsse von Chinesinnen”, Zeitschrift für Ethnologie 37, plate 8. Staatsbibliothek zu Berlin—Preußischer Kulturbesitz.

Figure 6.4 [Unknown] Wollenberg and [Unknown] Fränkel, X-ray of the feet of a 32-year-old woman, ca. 1905. Charité Universitätsmedizin CCM, Anatomische Sammlung, Fächerverbund Anatomie. Photo: Barbara Herrenkind.

Figure 6.5 Hans Virchow, ink drawing on salt paper, copy of the X-rayed foot of a 32-year-old woman, ca. 1905. Charité Universitätsmedizin CCM, Anatomische Sammlung, Fächerverbund Anatomie. Photo: Barbara Herrenkind.

Beyond retouching 85 draw with a measure of accuracy the outlines of those bones that overlap and hence have left only blurry images in the radiograph, he relied on his earlier studies (see Figure 6.2). Without giving a step-by-step illustration of Virchow’s procedure, this sheet shows how he drew more or less delicate ink lines over the faint salt-paper print to bring out the shapes of the bones.

In a second step, he made platinotype copies of the radiographs “that were intentionally left so faint that only the retouching process rendered them dark enough for printing”.¹⁴ As in the previous picture, some of the brushstrokes are conspicuously confident, suggesting that this image was another preliminary stage (Figure 6.6). Virchow obtained the final product by transferring the drawings produced in the first step onto these copies. The goal, he wrote, was a composite image that “combined as much as possible the character of the radiograph with [the drawing’s] distinctiveness of forms”.¹⁵

The final product is a black-and-white watercolor painting that presents a peculiar fusion of the translucency of the radiograph with the clearly delineated forms of the drawing (Figure 6.7). To the unsuspecting viewer, images such as these suggest especially well-made X-rays, or perhaps a better kind of radiography.

In the case of the 20-year-old woman’s foot, too, the surviving studies illustrate various preliminary stages and demonstrate how Virchow translated the original image into a crystal-clear depiction without forfeiting the characteristic aesthetic of the radiograph. Compared to the drawings of bones obtained by way of salt paper prints of photographs (Figure 6.2), the final products in this instance look distinctly like radiographs.

Figure 6.6 Hans Virchow, ink drawing on salt paper, copy of the X-rayed foot of a 32-year-old woman, ca. 1905. Charité Universitätsmedizin CCM, Anatomische Sammlung, Fächerverbund Anatomie. Photo: Barbara Herrenkind.

Figure 6.7 Hans Virchow, ink and pencil drawing on a pale copy of the X-rayed foot of a 32-year-old woman, ca. 1905. Charité Universitätsmedizin CCM, Anatomische Sammlung, Fächerverbund Anatomie. Photo: Barbara Herrenkind.

Virchow’s critique of the image

Of particular interest in the present context is the section of Virchow’s article in which he offers an extensive discussion of the epistemological advantages of different forms of depiction and defends his use of such hybrid representations.

Virchow concedes that he has “quite deliberately brought a subjective aspect into play”, a decision he justifies by noting that “without it, the images would not have achieved the necessary degree of intelligibility”.¹⁶

As in the first article, where he defended the use of ink drawings to illustrate bones, Virchow addresses what he calls “the heightened sensitivity of our time to ‘objective fact’”.¹⁷ In an early study on the movements of the hand, he had already lamented: “Where we formerly had too much explanation and too little fact, we now have too little explanation and too much fact”.

So Virchow warns the reader against an uncritical use of technical images and the “superficial notion ... that all we need to do is read the objective fact in the image”.¹⁹ The radiographic technique was obviously instrumental in sharpening this critical stance because, as Virchow writes, X-ray pictures in particular pose “an immense risk of misinterpretation”; he compares the radiograph to “hardly legible handwriting”²⁰ that must be painstakingly deciphered, and concludes: “The lesson that the study of x-ray images teaches with unparalleled clarity is this: the only true scientific objectivity consists in a subjectivity purified to the highest possible degree by critical examination and diligence”.²¹

That is a direct assault on what seems to have been the universally shared ideal of objectivity around 1900,²² an ideal that the investigation of visual practices of the nineteenth century has already revealed to be a rhetorical construction.²³ Virchow’s use and critique of images suggest that the rise of new imaging techniques and forms of representation such as radiography in the final years of this century are about to make this ideal of objectivity entirely untenable.

But Virchow’s critique of the image goes further still: as he sees it, the very automatic quality of radiography is a source of potential error. Virchow lists the technical-instrumental factors that condition the radiographic image; I’ve mentioned some of them: “the direction of irradiation, the arrangement of the object, and other circumstances”. Because of these influences, Virchow argues, any given radiograph is “in itself ... eminently subjective”, so that “it makes no sense ... to speak of an objective

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x-ray image .

To understand what the picture shows we must understand the conditions that shaped its creation. It seems incontrovertible to Virchow that we can arrive at knowledge of the object only when we take into consideration the conditionality of any depiction (and that we can accordingly never solely rely on one examination method).

This suggests a fundamentally critical view of images and an understanding of technology that regards any image as an artifact, as a product of techné, which is to say, of human making.

Allow me to suggest the implications for the questions under consideration in the present volume. One tentative definition of “hybrid” imagery proposed to date is that it represents a conjunction of technical and manual imaging techniques. If Virchow is right, any technical imaging process must be recognized as being genuinely hybrid in and of itself, and in studying it we must examine its products as products of human making.

You can see how Virchow’s ink drawings based on radiographs as well as the media critique associated with this practice confidently sidestep any charge of subjectivism and stake out a position beyond the debate about the permissibility of retouching technically generated pictures. If any such picture is already the result of an intervention, any use of technology is ipso facto already hybrid.

Notes

• 1 Wilhelm Conrad Röntgen, “Ueber eine neue Art von Strahlen: Vorläufige Mittheilung”, Sitzungsberichte der Würzburger Physikalisch-Medizinischen Gesellschaft, no. 9 (1895): 132-141. A translation of Röntgen’s note was published some weeks later in Science 3, no. 59 (February 14, 1896): 227-231.
• 2 Hans Virchow to Wilhelm Conrad Röntgen, January 12, 1896, archive of the Deutsches Röntgen-Museum (German X-Ray Museum), Remscheid-Lennep.
• 3 See Hans Virchow, “Über Röntgen-Aufnahmen der Hand”, Sitzungs-Bericht der Gesellschaft forschender Freunde zu Berlin, no. 5 (1899): 3.
• 4 Ibid., 4.
• 5 See Hans Virchow, “Das Verhalten des Navikulare bei Flexionsbewegungen der Hand”, Medizinische Klinik, no. 24 (1911): 4.
• 6 Virchow, “Über Röntgen-Aufnahmen der Hand”, 1.
• 7 Virchow, “Das Verhalten des Navikulare”, 11.
• 8 Ibid., 5.
• 9 Hans Virchow, “Die Weiterdrehung des Naviculare carpi bei Dorsalflexion, und die Bezeichnungen der Handbänder”, in Verhandlungen der Anatomischen Gesellschaft auf der sechzehnten Jahresversammlung in Halle a. S., ed. Halle an der Saale (Jena: Fischer, 1902), 114.

Hermann Stieve, “Hans Virchow zum Gedenken”, Anatomischer Anzeiger 92, no. 22/24 (1942): 310.

Hans Virchow, “Das Skelett eines verkrüppelten Chinesinnen-Fusses”, Zeitschrift für Ethnologie 35, no. 2/3 (1903): 266-316.

Hans Virchow, “Weitere Mitteilungen über Füsse von Chinesinnen”, Zeitschrift für Ethnologie 37, no. 4 (1905): 546-568.

Ibid.

Ibid., 550.

Ibid.

Ibid.

Virchow, “Das Skelett”, 281.

Hans Virchow, “lieber Einzelmechanismen am Handgelenk”, Verhandlungen der physiologischen Gesellschaft zu Berlin, no. 5-9 (1901-1902), 2.

Virchow, “Weitere Mitteilungen über Füsse von Chinesinnen”, 551.

Ibid.

Ibid.

See Lorraine Daston and Peter Galison, Objectivity (New York: Zone Books, 2007). Virchow’s critical stance correlates with the advent of a new ideal that Daston and Galison call “trained judgment”.

See, for example, the introductions and chapters in the present volume.

Virchow, “Weitere Mitteilungen über Füsse von Chinesinnen”, 551.