Pratt began appearing in theatrical performances in Canada,[when?] and during this period he chose Boris Karloff as his stage name. Some have theorised that he took the stage name from a mad scientist character in the novel The Drums of Jeopardy called "Boris Karlov". However, the novel was not published until 1920, at least eight years after Karloff had been using the name on stage and in silent films, opening the possibility that the Karlov character might have been named after Karloff after the novel's author noticed it in a cast listing and liked the sound of it rather than simply being a coincidence. Warner Oland played "Boris Karlov" in a film version in 1931. Another possible influence was thought to be a character in the Edgar Rice Burroughs fantasy novel H. R. H. The Rider which features a "Prince Boris of Karlova", but as the novel was not published until 1915, the influence may be backward, that Burroughs saw Karloff in a play and adapted the name for the character. Karloff always claimed he chose the first name "Boris" because it sounded foreign and exotic, and that "Karloff" was a family name (from Karlov—in Cyrillic, Карлов—a name found in several Slavic countries, including Russia, Ukraine and Bulgaria ). However, his daughter Sara Karloff publicly denied any knowledge of Slavic forebears, "Karloff" or otherwise. One reason for the name change was to prevent embarrassment to his family. Whether or not his brothers (all dignified members of the British Foreign Service) actually considered young William the "black sheep of the family" for having become an actor, Karloff apparently worried they felt that way. He did not reunite with his family until he returned to Britain to make The Ghoul (1933), extremely worried that his siblings would disapprove of his new, macabre claim to world fame. Instead, his brothers jostled for position around him and happily posed for publicity photographs. After the photo was taken, Karloff's brothers immediately started asking about getting a copy of their own. The story of the photo became one of Karloff's favorites.