Morphogenesis is one of the fundamental processes of developing life. Gastrulation, especially, marks a period of major translocations and bustling rearrangements of cells that give rise to the three germ layers. It was also one of the earliest fields in biology where cell movement and behaviour in living specimens were investigated. This article examines scientific attempts to understand gastrulation from the point of view of cells in motion. It argues that the study of morphogenesis in the twentieth century faced a major dilemma, both epistemological and pictorial: representing form and understanding movement are mutually exclusive, as are understanding form and representing movement. The article follows various ways of modelling, imaging, and simulating gastrular processes, from the early twentieth century to present-day systems biology. The first section examines the tactile modelling of shape changes, the second cell cinematography, mainly the pioneering work of the German embryologists Friedrich Kopsch and Ernst Ludwig Gräper in the 1920s but also a series of classic, yet not widely known, studies of the 1960s. The third section deals with the changes that computer simulation and live-cell imaging introduced to the modelling of shape change and the study of cell movement at the turn of the twenty-first century. Although live-cell imaging promises to experiment upon and represent the living body simultaneously, I argue that the new visuals are an obstacle rather than a solution to the puzzle of understanding cell motion.

Historians have often described embryology and concepts of development in the period around 1800 in terms of "temporalization" or "dynamization". This paper, in contrast, argues that a central epistemological category in the period was "rhythm", which played a major role in the establishment of the emerging discipline of biology. I show that Caspar Friedrich Wolff's epigenetic theory of development was based on a rhythmical notion, namely the hypothesis that organic development occurs as a series of ordered rhythmical repetitions and variations. Presenting Christian Heinrich Pander's and Karl Ernst von Baer's theory of germ layers, I argue that Pander and Baer regarded folding as an organizing principle of ontogenesis, and that the principle's explanatory power stems from their understanding of folding as a rhythmical figuration. In a brief discussion of the notion of rhythm in contemporary music theory, I identify an underlying physiological epistemology in the new musical concept of rhythm around 1800. The paper closes with a more general discussion of the relationship between the rhythmic episteme, conceptions of life, and aesthetic theory at the end of the eighteenth century.

In the twenty-first century, computer simulations have become ubiquitous. It is hard to think of any sciences, from the natural to the social, to the life sciences and the humanities, that have not developed, in one way or another, methodologies involving computational tools and, in particular, computer simulations. However, what are computer simulations? Surveying the increasingly vast literature in the field, the predominant impression is twofold: First, there seems to be a unified understanding of what computer simulation consists of. In research practices, in scientific literature, and in the public realm we find undiscriminating talk of "simulations", as a collective noun, implying that they involve roughly the same approach regardless of the knowledge domains, applications or research aims to which they are applied. Second, computer simulations are seen as technological agents of change, a radical new technology which came into the world in the wake of the humanitarian and intellectual devastations of the Second World War, and in doing so, they almost immediately transformed knowledge production in the sciences and the way we act in the world. Research has been devoted to the many questions raised by computer simulations, be they epistemological, political, social or economic.  But historical studies of computer simulation are strikingly absent from the field's growing corpus. To right this, the aim of this special issue is to critically reassess the predominant view of computer simulations as a disruptive and unified computational technology by setting them in a historical perspective. This special issue collects four historical case studies that focus on exemplary instances of what are today regarded as computer simulations: mathematical problem-solving with the ENIAC computer (Electronic Numerical Integrator and Computer) in the s; the introduction of Monte K

This issue of Science in Context is dedicated to the question of whether there was a “cinematographic turn” in the sciences around the beginning of the twentieth century. In 1895, the Lumière brothers presented their projection apparatus to the Parisian public for the first time. In 1897, the Scottish medical doctor John McIntyre filmed the movement of a frog's leg; in Vienna, in 1898, Ludwig Braun made film recordings of the contractions of a living dog's heart (cf. Cartwright 1992); in 1904, Lucien Bull filmed in slow motion a bullet entering a soap bubble. In 1907 and 1908, respectively, Max Seddig and Victor Henri recorded Brownian motion with the help of a cinematograph (Curtis 2005). In 1909, the Swiss Julius Ries was one of the first to film fertilization and cell division in sea urchins (Ries 1909). In that same year in Paris, Louise Chevroton and Frédéric Vlès used a film camera to observe cell division in the same object (Chevroton and Vlès 1909). As early as 1898, the Parisian surgeon Eugène-Louis Doyen began filming several of his operations, among them the spectacular separation of the Siamese twins Doodica and Radica (Bonah and Laukötter 2009). And in England, the scientist and zoologist Francis Martin Duncan produced an array of popular-scientific films for Charles Urban: “The unseen world: A series of microscopic studies” was presented to the public in the Alhambra Theatre in London for the first time in 1903 (see Gaycken in this issue).