Artist, born in Münchenbuchsee, near Bern, Switzerland. He studied at Munich and settled there, becoming a member of the Blaue Reiter group (1911--12). He then taught at the Bauhaus (1920--32), and after returning to Bern (1933) many of his works were confiscated in Germany. His early work consists of bright watercolours, but after 1919 he worked in oils, producing small-scale, mainly abstract pictures, as in his "Twittering Machine' (1922, New York).