Marx Brothers "The Cocoanuts" (1925–1926) and "Animal Crackers" (1928–1929). Playwright George S. Kaufman worked on the last two and helped sharpen the brothers' characterizations. Out of their distinctive costumes, the brothers looked alike, even down to their receding hairlines. Zeppo could pass for a younger Groucho, and played the role of his son in "Horse Feathers". A scene in "Duck Soup" finds Groucho, Harpo, and Chico all appearing in the famous greasepaint eyebrows, mustache, and round glasses while wearing nightcaps. The three are indistinguishable, enabling them to carry off the "mirror scene" perfectly. The stage names of the brothers (except Zeppo) were
Zeppo Marx all four Marx Brothers equally — "When the "four" Marx brothers are on the screen, it's a riot" [emphasis added] — and went on to describe each of the brothers' unique style of comedy, and praised Zeppo as "the handsome but dogged straight man with the charisma of an enamel washstand." In her book "Hello, I Must be Going: Groucho & His Friends", Charlotte Chandler defended Zeppo as being "the Marx Brothers' interpreter in the worlds they invaded. He was neither totally a straight man nor totally a comedian, but combined elements of both, as did Margaret Dumont. Zeppo's importance