EN
Jan Dembowski was an outstanding Polish biologist, protistologist and animal psychologist. After biological studies in St. Petersburg (Russia), he received his PhD degree at the Warsaw University. He was then professor at the Free Polish University, and worked at the Nencki Institute of Experimental Biology in Warsaw, and then at the Stephen Báthory University in Vilnius. After WW II he worked at the Łódź University, and took part in the restoration of the Nencki Institute, where he became Head of the Department of Biology and Director (1947–1960). He was the fi rst President of the new Polish Academy of Sciences (1952–1956). Dembowski wrote numerous books and scientifi c papers, both theoretical and experimental. His most important studies dealt with the behaviour of a protozoan Paramecium caudatum, larvae of the caddisfl y Molanna angustata and various crabs. In Paramecium he analysed, among others, active choice of food on the basis of its physico-chemical features, patterns of swimming and geotactic behaviour. He also demonstrated the inability of Paramecium to show avoidance learning in response to light or shadow coupled with the electric shock. His research on behaviour of arthropods was focused mainly on the question of behavioural plasticity. In his book “Animal Psychology” (1950) he put forward a precursory thesis of scientifi c revolutions, broadly accepted only in 1962 when it was proposed again by Th. S. Kuhn. Dembowski played the piano and was a passionate hunter.