title: Karl ernst von Baer's 'Uber Entwickelungsgeschichte der Thiere II' and its unpublished drawings.
abstract: In 1828 Karl Ernst von Baer (1792-1876) published his seminal Uber Entwickelungsgeschichte der Thiere. Beobachtung und Reflexion. In the preface he announced that a second volume with one copper plate would be finished 'in a few weeks'. However, it took nine years until the unfinished second volume was released, with four copperplates. In his 'Autobiography', von Baer did not clarify the reasons why he did not finish his research program of comparative embryology. The paper attempts to elucidate them, furnished by archival documents and von Baer's unpublished embryological drawings. Our sketch of a few figures will show that (1) von Baer searched for 'analogies' (homologies) as a unifying principle and (2) explained the mechanisms of embryogenesis by physiological reasoning (electromagnetism). The main objective is to show that technical problems in illustrating and conceptual difficulties impeded von Baer's ambitious research program.
authors.affiliation: Institute of Zoology and Botany, 51005 Estonian Agricultural University Veski st. 4, Tartu, Estonia.
authors.forename: Erki
authors.initials: E
authors.lastname: Tammiksaar
authors.forename: Sabine
authors.initials: S
authors.lastname: Brauckmann
mesh_terms: D000717:Anatomy, Comparative / Q000266:history*; D004626:Embryology / Q000266:history*; D047108:Embryonic Development; D049672:History, 19th Century; D006801:Humans; D008488:Medical Illustration / Q000266:history*