August Leskien (German: ['l?ski?n]; 8 July 1840 – 20 September 1916) was a German linguist active in the field of comparative linguistics, particularly relating to the Baltic and Slavic languages.
Author: The caption says «W. Str. fec.»; most likely the German linguist Wilhelm Streitberg (1864–1925). Source: Indogermanisches Jahrbuch I (1913) [1] License: CC-PD-Mark PD Old