In recent decades, investigations into the relationship between science and art have produced a wealth of intriguing new work in the history of science. These studies have played a decisive role in opening up new lines of inquiry for the field and, at least in part, in reshaping its fabric. Nick Hopwood's book, which belongs to this trend, argues that attempts to take the visual dimension of science seriously have been limited thus far by their focus on a few individual, iconic depictions rather than on the wider history of the emergence of scientific images. As Hopwood rightly insists, “we need to paint on a larger canvas to realize the potential of the approach,” and his goal is “to find out how pictures of knowledge succeed and fail, become accepted and cause trouble” (3). To achieve better insight into science's visual dimension, the author embarks on a detailed historical reconstruction of the controversy surrounding the scientific accuracy of Ernst Haeckel's images of embryos. In doing so, he stretches the canvas of his study both temporally—by adopting a long-term view—and spatially: by contextualizing it within the wider scientific discourse on embryology, and by tracing the migration of the discourse about Haeckel's images from Germany to the United States.

Although Hopwood's reconstruction follows a roughly chronological approach that reaches back to the late eighteenth century, tracing the discussion of Haeckel's images up to the present day, it is, by no means, a linear narrative. Instead, each chapter sheds light on different themes in the discussion and in the images. The book thus gradually shifts from the beginnings of modern embryology and its images (e.g., by Thomas Soemmerring), through Haeckel and his renewal of embryological imagery, to the heated disputes that Haeckel's images still cause today.

Using this approach, Hopwood identifies the gridded representation of embryological development Haeckel introduced in Die natürliche Schöpfungsgeschichte (1868) as a major source of both controversy and the author's popularity. These grids visually juxtapose different stages in the development of embryos of different species, allowing for direct comparison. Hopwood shows how, from early on, critics pointed to the schematic and idealizing inaccuracy of these images. Yet, he also notes that it is the persuasiveness and accessibility of these images that continue to make them so useful as conceptual illustrations in evolutionary science. The authority of Haeckel's work was thus questioned because of his tendency to construct and abstract his images from various sources. Haeckel's intention, the author argues, was, in fact, precisely that: to provide idealized images of certain types, rather than exact copies of actual individuals, in order to emphasize the common origins of various species. The book then traces the multifaceted scientific and cultural responses to the images in the nineteenth and twentieth centuries.

What drives Hopwood's argument forward and holds it together is not his analysis of Haeckel's image production, but rather his examination of the development of embryology and the role of changes in image production that Haeckel introduced in his effort to popularize and establish embryology as a field of scientific inquiry—all of which took place in the context of resistance against Charles Darwin's theory of evolution and the notion that humans and other animals had common origins. The controversy surrounding Haeckel's images is a central theme, but Haeckel's Embryos offers much more than its title suggests and is more than merely a simple study of why and how scientific images fail. Moving skillfully back and forth among various actors and timespans, while integrating the images and the controversy they sparked into the history of their emergence, the author paints a picture of the forces and scientific cultures at play in the construction and establishment of knowledge, theory, and truths.

With the broad view he adopts, the careful dissecting of a wealth of different sources, and his fine-grained analysis of the controversy, Hopwood reveals that much was at stake in Haeckel's images. Theoretical, methodological, and paradigmatic quarrels were buried beneath arguments about the scientific adequacy of these depictions, and they related as much to the acceptance of evolutionary theory—and to the contesting of empirical and speculative approaches within scientific procedures—as to struggles about what counts as scientifically acceptable knowledge. At its heart, Hopwood's study brings into focus the struggle over the difference between humans and animals, as well as arguments about the exceptionalism of the former.

Haeckel's Embryos reconstructs in painstaking and impressive detail the development of embryology as a scientific field inseparable from Darwinism, as well as the role that images—and Haeckel's specific style of natural imagery, in particular—played as popularizing and conceptually illustrative devices in scientific, and, to an even greater extent, public discourse. Haeckel is an eminently fitting figure for telling this story—and through it, the story of science communication. The density and skill with which Hopwood integrates various levels of discourse and brings them into conversation with one another significantly raise the bar for future studies in the history of science. Yet, if we measure Hopwood by his own observation—that “taking the visual dimensions seriously” uncovers “the importance of nonverbal communication and of competition between different approaches to producing and using images” (2)—his approach falls short. Haeckel's research practices and how they led to the production of the images are absent from Hopwood's study. Instead, like so many investigations of the relationship between science and art, Hopwood's consideration of art and the related processes of image production remains little more than an evaluation of illustrational qualities and accuracy rather than an alternative approach to producing knowledge of nature.

As a history of embryology, Haeckel's Embryos is a study of the finest quality. As an investigation of visual strategies, it could have offered less historical detail and instead greater consideration of the media qualities and the place of artistic mediation in Haeckel's research procedures, as well as of the way in which these processes fit into wider debates about scientific methodology more generally.