The present account aims to contribute to a better characterization of the state and the dynamics of embryological knowledge at the dawn of the molecular revolution in biology. In this study, Albert Dalcq (1893-1973) was chosen as a representative of a generation of embryologists who found themselves at the junction of two very different approaches to the study of life: the first, focusing on global properties of organisms; the second focusing on the characterization of basic molecular constituents. Though clearly belonging (...) to the organismic tradition, Dalcq was already blending his experimental and explanatory practices with biochemical aspects by the 1930s. Principally based on published sources, the present analysis focuses on the conceptual definitions, modifications and interrelations on which Dalcq's explanation of development rested. Among these are variant process concepts such as gradients and fields, which are often thought to have strongly holistic implications. I will argue that Dalcq's version of these concepts was compatible with a more reductionist treatment of embryos than was accepted by most embryologists as late as the 1950s, pointing to some extent toward the recent molecular characterization of gradients by molecular geneticists such as Christiane Nüsslein-Volhard. Moreover, I will show how the embryological research program of Dalcq and his pupil Jean Brachet has been largely instrumental in the development of molecular biology in Belgium. (shrink)

This essay aims to shed new light on the relations between physiology and psychology in the late nineteenth and early twentieth centuries by focusing on the use of unicellular organisms as research objects during that period. Within the frameworks of evolutionism and monism advocated by Ernst Haeckel, protozoa were perceived as objects situated at the borders between organism and cell and individual and society. Scholars such as Max Verworn, Alfred Binet, and Herbert Spencer Jennings were provoked by these organisms to (...) undertake experimental investigations situated between general physiology and psychology that differed from the physiological psychology advocated by Wilhelm Wundt. Some of these investigations sought to locate psychological properties in the molecular structure of protoplasm; others stressed the existence of organic and psychological individuality in protozoa. In the following decades, leading philosophers such as Friedrich Nietzsche, Charles Sanders Peirce, and Henri Bergson, as well as psychological researchers like Sigmund Freud, integrated the results of these investigations into their reflections on such problems as the nature of the will, the structure of the ego, and the holistic nature of the reactions of organisms to their environment. (shrink)

This paper aims to clarify the consequences of new scientific and philosophical approaches for the practical-theoretical framework of modern developmental biology. I highlight normal development, and the instructive-permissive distinction, as key parts of this framework which shape how variation is conceptualised and managed. Furthermore, I establish the different dimensions of biological variation: the units, temporality and mode of variation. Using the analytical frame established by this, I interpret a selection of examples as challenges to the instructive-permissive distinction. These examples include (...) the phenomena of developmental plasticity and transdifferentiation, the role of the microbiome in development, and new methodological approaches to standardisation and the assessment of causes. Furthermore, I argue that investigations into organismal development should investigate the effects of a wider range of kinds of variation including variation in the units, modes and temporalities of development. I close by examining various possible opportunities for producing and using normal development free of the assumptions of the instructive-permissive distinction. These opportunities are afforded by recent developments, which include new ways of producing standards incorporating more natural variation and being based on function rather than structure, and the ability to produce, store, and process large quantities of data. (shrink)

This is an attempt to interpret the history of mechanism vs. vitalism in relation to the changing framework of culture and to show the interrelation between both these views and experimental science. After the scientific revolution of the seventeenth century, causal mechanism of classical physics provided the framework for the study of nature. The teleological and holistic properties of life, however, which are incompatible with this theory yielded — as a result both of internal developments within biology and of a (...) general reaction against dogmatic rationalism — to a vitalistic interpretation of life which ascribed a mysterious force to living organisms. It will be shown that both mechanism and vitalism are related to the experimental climate of the time in which they were popular. The controversy has now lost its raison d'être as a result of the development of the theory of systems and of a better understanding of the chemistry and evolution of life. (shrink)

In biology the term “vitalism” is usually associated with Hans Driesch’s doctrine of the entelechy: entelechies were nonmaterial, bio-specific agents responsible for governing a few peculiar biological phenomena. Since vitalism defined as such violates metaphysical materialism, the received view refutes the doctrine of the entelechy as a metaphysical heresy. But in the early twentieth century, a different, non-metaphysical evaluation of vitalism was endorsed by some biologists and philosophers, which finally led to a logical refutation of the doctrine of the entelechy. (...) In this non-metaphysical evaluation, first, vitalism was not treated as a metaphysical heresy but a legitimate response to the inadequacy of mechanistic explanations in biology. Second, the refutation of vitalism was logically rather than metaphysically supported by contemporary biological knowledge. The entelechy was not a valid concept, because vitalists could neither formulate vital laws, nor offer convincing examples of experimental indeterminism. (shrink)