A case-study of the interaction between philosophical context and observational data in the practice of Science.

The theories of pre-existence and epigenesis are typically taken to be opposing theories of generation in the seventeenth and eighteenth centuries. One can be a pre-existence theorist only if one does not espouse epigenesis and vice versa. It has also been recognized, however, that the line between pre-existence and epigenesis in the nineteenth century, at least, is considerably less sharp and clear than it was in earlier centuries. The debate (1759-1777) between Albrecht von Haller and Caspar Friedrich Wolff on their (...) theories of generation is usually taken to be a debate between a pre-existence theorist and an epigeneticist, and the supposed fact that these two theories of generation are mutually exclusive explains (so the story goes) the divide between Haller and Wolff. However, it’s not clear that Haller endorsed an especially robust form of pre-existence, and nor is it clear that Wolff’s theory of generation -- once he considered it carefully -- is clear epigenetic. Rather, Haller’s theory of generation is marked by traces of epigensis and Wolff’s theory has elements of pre-existence theory. This is not to say that their theories of generation are basically the same, but the debate between the two ought not to be framed in terms of pre-existence versus epigenesis. Their points of difference must be explained in some other way. In this way, their controversy bears characteristics of similar disputes over generation in the nineteenth century more than it resembles those in the seventeenth century. In this paper, I argue that (a) Haller’s and Wolff’s theories both blend elements from pre-existence and epigenesis; (b) but there are still deeply-rooted differences between the two generation theories; (c) one source of these differences is that Haller and Wolff have divergent conceptions of what an adequate explanation is; (d) we can see that they have different conceptions of what constitutes an adequate explanation by paying heed to their evaluations of Descartes’ epistemology and methodology in his theory of generation (such as it is); and (e) this shows that one of the main differences between Haller’s generation theory and that of Wolff is the degree to which each thinks we need to (and indeed can) explain the nature of the causes -- both efficient and final -- at play during the formation of organic beings. (shrink)

This collection of literature attempts to compile many of the classic works that have stood the test of time and offer them at a reduced, affordable price, in an attractive volume so that everyone can enjoy them.

Reinvestigating the work of the anatomist Wilhelm His (1831-1904) shows how engaging with models in three dimensions can revise our accounts of scientific change. His is known to historians of biology for articulating a mechanical approach to embryology and for inventing a section cutter, or microtome. Focusing on the wax models that he also made in the late 1860s shows how the other two innovations were linked; reconstructing embryos from the sections, His claimed, provided compelling evidence for mechanical views. The (...) next generation of embryologists appropriated His's work selectively. In the 1880s anatomists took up "plastic reconstruction" to visualize the complex forms of higher vertebrate, especially human, embryos. An increasingly dominant experimental embryology, by contrast, drew on His's mechanical approach but had little use for the waxes and effaced them from the history of his work. Recovering these models offers a fresh perspective on the transformation of a central science of animal life and enriches our understanding of the relations between representation in two dimensions and three. (shrink)

Edmund Beecher Wilson is generally celebrated for his contribution to chromosome theory and genetics, whereas opinion concerning his cytological thinking is often restricted to the idea that he provided evidence for the dominant role of the nucleus. But Wilson's cell theory was much more. It was a child of the German Zellforschung, and its attempt to provide a comprehensive cellular answer to a wide range of biological and physiological questions. Wilson developed a corpuscular, micromeristic and preformistic concept, and treated the (...) cell as an organism subject to ontogenetic and phylogenetic processes. He defended his comprehensive theory even in the 1920's, when cytological research had become specialised and directed at more practical goals. For many of his younger readers this concept might have seemed antiquated, but today many of its features sound surprisingly modern. (shrink)

Icons of knowledge -- Two small embryos in spirits of wine -- Like flies on the Parlon ceiling -- Drawing and Darwinism -- Illustrating the magic word -- Professors and progress -- Visual strategies -- Schematics, forgery, and the so-called educated -- Imperial grids -- Setting standards -- Forbidden fruit -- Creative copying -- Trials and tributes -- Scandal for the people -- A hundred Haeckels -- The textbook illustration -- Iconoclasm -- The shock of the copy.

Generelle Morphologie der Organismen - Allgemeine Grundzuge der organischen Formen-Wissenschaft mechanisch begrundet durch die von Charles Darwin reformierte Deskendenz-Theorie ist ein unveranderter, hochwertiger Nachdruck der Originalausgabe aus dem Jahr 1866. Hansebooks ist Herausgeber von Literatur zu unterschiedlichen Themengebieten wie Forschung und Wissenschaft, Reisen und Expeditionen, Kochen und Ernahrung, Medizin und weiteren Genres.Der Schwerpunkt des Verlages liegt auf dem Erhalt historischer Literatur.Viele Werke historischer Schriftsteller und Wissenschaftler sind heute nur noch als Antiquitaten erhaltlich. Hansebooks verlegt diese Bucher neu und tragt damit (...) zum Erhalt selten gewordener Literatur und historischem Wissen auch fur die Zukunft bei. (shrink)

Stem cells did not become a proper research object until the 1960 s. Yet the term and the basic mind-set—namely the conception of single undifferentiated cells, be they embryonic or adult, as the basic units responsible for a directed process of development, differentiation and increasing specialisation—were already in place at the end of the nineteenth century and then transmitted on a non-linear path in the form of tropes and diagrams. Ernst Haeckel and August Weismann played a special role in this (...) story. The first coined the term Stammzelle (stem cell), the second was the author of the first cellular stem-tree diagram. Even today, I shall argue, the understanding of stem cells, especially the popular perception, is to a large extent a Haeckelian–Weismannian one. After having demonstrated this, by analysing the terminology, in this essay I will focus on the use of cytogenetic tree diagrams between 1892 and 1925 and on the tacit understanding of stem cells that they transmit. (shrink)

It was thus the combination of observational and experimental approaches that ultimately led to confirmation of the outgrowth theory. The observational method was essential for defining various possible methods of nerve fiber development. The multicellular, protoplasmic bridge and outgrowth theories were each postulated to explain purely observational evidence. However, the lack of truly suitable equipment and techniques to study the developing nervous system made it impossible to agree on a single theory on this basis alone. The experimental method provided a (...) means of choosing between these theories. Without the preceding observations that had led to the formulation of various hypotheses, however, the experimental approach might not have been so successful, for the power of this method is more of selection than of generation.Therefore it is impossible to weigh separately the contributions of the observational and experimental approaches to the question of nerve fiber development. Both were necessary for the ultimate acceptance of the outgrowth theory. *** DIRECT SUPPORT *** A8402051 00004. (shrink)