DVT 183, 169
Algologie a protistologie na Německé univerzitě v Praze v meziválečném období II. Ernst Georg Pringsheim a Institut pro rostlinnou fyziologii
Algology and protistology at the German University in Prague in the inter-war period, II. Ernst Georg Pringsheim and Institute for Plant Physiology.
The study focuses on the life and work of Ernst Georg Pringsheim and his co-workers Viktor Czurda and Felix Mainx at the German University in Prague. In the years 1923–1938 E. G. Pringsheim was the director of the Institute of Plant Physiology at the Faculty of Science. Present study recapitulates Pringsheim′s career and shows how his studies established cultivation of microalgae and protists as one of the main research tools in this field. Besides the studies on cultivation, the present study also deals with Pringsheim′s studies on vascular plant development and his views on evolution of microorganisms. Finally, the study analyses the research of V. Czurda, F. Mainx and E. G. Pringsheim focused on sexual phenomena in microorganisms, including their controversy with Max Hartmann concerning the nature and substance of sexual reproduction.
Key words: Ernst Georg Pringsheim ● Victor Czurda ● Felix Mainx ● German University in Prague ● history of biology ● algology
Since 1920s algae and bacteria were in the main focus of the research activities at the Institute of Plant Physiology of the German University in Prague. This research program was established by Ernst Georg Pringsheim (1881–1970), who became the full professor of the faculty and the head of the department in 1923. His research mostly concentrated on culturing microorganisms, which led to foundation of the Prague Culture Collection of Algae in 1928. In addition, he also carried out the research on bacterial diversity and leaf morphogenesis. The department also included two younger biologists, Viktor Czurda (1897–1945) and Felix Mainx (1900–1983), who participated on isolation of new strains for the collection. In addition, they published a number of studies focused on nature of sexual reproduction in microorganisms and algae. In contrast to theories of Max Hartmann and his collaborators, Czurda, Mainx and Pringsheim argued that male and female polarity is not necessary for sexual processes and should be viewed as a derived feature of a more basic mechanism based solely on merging sexually competent nuclei and cells. With the end of the first Czechoslovak Republic in October 1938 Pringsheim′s research group collapsed. Due to his Jewish origin he was removed from the university. Thanks to his scientific colleagues in Great Britain E.G. Pringsheim and his family were able to emigrate to UK in February 1939. Conversely, Victor Czurda became the head of the department, and later also the dean of the faculty and the vice-rector of the university. However, the strains isolated at the Department of Plant Physiology in the inter-war period provided a basis for four major culture collections of microalgae established after the 2nd World War.
Přírodovědecká fakulta UK, Katedra botaniky
Benátská 2 CZ-128 43 Praha 2
DVT 183, 197
Algebra v Pacioliho díle Summa (1494)
Algebra in Pacioli’s work Summa (1494).
Summa de Arithmetica, Geometria, Proportioni et Proportionalita, published in Venice for the first time, was then probably the first printed compendium of mathematics, and it became an important starting point for the development of mathematics in Italy during the whole 16th century, which is famous exactly for its excellent algebraic discoveries. In the study, we wish to show the real form of Pacioli’s algebraic thinking, the sources he was relying on consciously and how it could have been the starting point for the next development.
Keywords: Luca Pacioli ● Summa de Arithmetica Geometria Proportioni et Proportionalita ● 1494 ● algebra ● Italy
The study tries to understand and explain the algebraic part of Pacioli’s work without mathematical modernization of his knowledge, and thus to come to the perception of his effort in the given period in history as well as its contemporary task. The author concludes that Pacioli tried to combine the contemporary arithmetic-algebraic practice, which he knew very well, and the results of antique authors though he knew those only partially (e. g. he did not know Diofantes’ Arithmetic); he relied mainly on Euclides’ The Elements and Boetius’ Arithmetic. He may have been aware of incompleteness of the theory of irrationalities in the 10th book of The Elements but he was not able to overcome them. From there, perhaps his scepticism had passed when it comes to solving cubic equations. Despite these and other weaknesses, Pacioli’s summarizing interpretation became one of the important foundations of achievements in algebra of the 16th century, finished by its negation in the “new algebra” of François Viète about 100 years later.