Armin von Tschermak-Seysenegg (1870-1952): Physiologist and Co-'Rediscoverer' of Mendel's laws.

The 'rediscovery' of Mendel's laws in 1900 was a turning point in modern research of heredity/genetics. According to the traditional view, adopted and fostered by many textbooks of genetics, Mendel's principles were presented in the first half of 1900 simultaneously and independently by three biologists (H. de Vries, C. Correns, E. v. Tschermak-Seysenegg). Having thus laid the foundations of further development, the 'rediscovery' continues to attract considerable interest. Since the 1950s, however, serious questions arose concerning both the chronology and specific conceptual achievement of the scientists involved. Not only the independence but also parallelism was analysed in the context of individual research programmes of these three scholars. The youngest of them, Erich v. Tschermak-Seysenegg, was even excluded from the list of 'rediscoverers'. The aim of this paper is to use new archival evidence and approximate the contribution of the physiologist and ophthalmologist Armin von Tschermak-Seysenegg (1870-1952) to the events of 1900 and 1901.

'Further Development' of Mendel's legacy? Erich von Tschermak-Seysenegg in the context of Mendelian-biometry controversy, 1901-1906.

The contribution of Erich von Tschermak-Seysenegg (1871-1962) to the beginning of classical genetics is a matter of dispute. The aim of this study is to analyse, based on newly accessible archive materials, the relevance of his positions and theoretical views in a debate between advocates of early Mendelian explanation of heredity and proponents of biometry, which took place in England around 1901-1906. We challenge not only his role of an 'external consultant', which at the time de facto confirmed his status of 'rediscoverer' of Mendel's work but also analyse his ambivalent positions which are to be seen as a part of 'further development' (Weiterführung), a development of Mendel's legacy as he understood it. Second, there is an interesting aspect of establishing connections within an 'experimental culture' along the Mendel's lines of thought that was parallel to the first step of institutionalizing the new discipline of Genetics after 1905/06. Part of the study is also the analysis of contribution of his older brother Armin von Tschermak-Seysenegg (1870-1952) who--much like in the case of 'rediscovery' of 1900-1901--was for his younger brother an important source of theoretical knowledge. In this particular case, it regarded Bateson's 'Defence' of Mendel from 1902.

Psychoontogeny and psychophylogeny: Bernhard Rensch's (1900-1990) selectionist turn through the prism of panpsychistic identism.

Toward the end of the 1930s, Bernhard Rensch (1900-1990) turned from Lamarckism and orthogenesis to selectionism and became one of the key figures in the making of the Synthetic Theory of Evolution (STE). He contributed to the Darwinization of biological systematics, the criticism of various anti-Darwinian movements in the German lands, but more importantly founded a macroevolutionary theory based on Darwinian gradualism. In the course of time, Rensch's version of the STE developed into an all-embracing metaphysical conception based on a kind of Spinozism. Here we approach Rensch's "selectionist turn" by outlining its context, and by analyzing his theoretical transformation. We try to reconstruct the immanent logic of Rensch's evolution from a "Lamarckian Synthesis" to a "Darwinian Synthesis". We will pay close attention to his pre-Darwinian works, because this period has not been treated in detail in English before. We demonstrate an astonishing continuity in topics, methodology, and empirical generalizations despite the shift in Rensch's views on evolutionary mechanisms. We argue that the continuity in Rensch's theoretical system can be explained, at last in part, by the guiding role of general methodological principles which underlie the entire system, explicitly or implicitly. Specifically, we argue that Rensch's philosophy became an asylum for the concept of orthogenesis which Rensch banned from evolutionary theory. Unable to explain the directionality of evolution in terms of empirically based science, he "pre-programmed" the occurrence of human-level intelligence by a sophisticated philosophy combined with a supposedly naturalistic evolutionary biology.