Marx Brothers stage during the middle of a Groucho monologue to see if Groucho would be thrown off. However, to the audience's delight, Groucho merely reacted by commenting, "First time I ever saw a taxi hail a passenger". When Harpo chased the girl back in the other direction, Groucho calmly checked his watch and ad-libbed, "The 9:20's right on time. You can set your watch by the Lehigh Valley." The brothers' vaudeville act had made them stars on Broadway under Chico's management and with Groucho's creative direction—first with the musical revue "I'll Say She Is" (1924–1925) and then with two musical comedies:
Biographies of Karl Marx (1925), Japanese (1930), Spanish (1932), and English (1935). Marx: Man and Fighter is a biography by Boris Nicolaievsky, first published in German in 1933. It was translated into English by Otto Mänchen-Helfen and published in 1936. Some subsequent English editions restore the notes, appendices, and bibliography omitted from the first English edition. Karl Marx: His Life and Environment is a 1939 biography of Karl Marx by Isaiah Berlin, in which Berlin argues that Marx's system of thought depends upon indefensible metaphysical presuppositions. Karl Marx: His Life and Thought is a 1973 biography of Karl Marx by political scientist David McLellan.