became highly popular in spite of their high musical demands. Herbert is also known for his "variation" songs, which consist either of a series of refrains displaying different styles, or of several variations of the same melody. For example, "Serenades of All Nations" from The Fortune Teller demonstrates serenades from colourful national traditions, sung and danced by a ballerina. "The Song of the Poet" from Babes in Toyland provides variations on the lullaby "Rock-a-bye Baby" by presenting it first as a brassy march, then in Neapolitan style, and finally as a cakewalk. The best of Herbert's operetta music is challenging, calling for trained singers. He often wrote his operettas with a particular singer in mind. During his career he had occasion to work with three great prima donnas: Alice Nielsen, Fritzi Scheff, and Emma Trentini. For them, he wrote leading parts in The Fortune Teller and The Singing Girl (Nielsen), Babette, Mlle. Modiste, The Prima Donna and Mlle Rosita (Scheff), and Naughty Marietta (Trentini). He would also write shows for popular comedians of the day or noted producers. Some of these were spectacular successes (The Red Mill, written for the comedy team of David C. Montgomery and Fred Stone, was Herbert's most financially successful show.), while others were dismal failures (When Sweet Sixteen, written for Joe Weber, who pulled out of the production, which lasted only twelve performances on Broadway.). Although Herbert had not been exposed to Gilbert and Sullivan before his arrival in the U.S. in 1886, their popularity led him to adopt some of their musical and dramatic sensibilities. An example of this is the quintet "Cleopatra's Wedding Day" from The Wizard of the Nile. One of his early successes, The Serenade, borrows many of its situations from Ruddigore, Iolanthe and The Pirates of Penzance. The work's librettist, Harry B. Smith, went on to steal more Gilbertian ideas for future operettas with Herbert, who often would complement these ideas with music reminiscent of Sullivan. The Singing Girl, co-written by Smith and Stanislaus Stange, recalls The Mikado, and includes the plot element of a law against kissing without a licence. Herbert tended to use a slightly larger orchestra than Sullivan did in his comic operas, mostly through use of more types of percussion and occasionally by adding a harp. He generally wrote his own orchestrations, which were admired by music critics and other composers. In revivals of his works,