The Student Prince was the single longest-running musical production of its decade. But if its producers, the Shuberts, had had their way, it never would have even opened. The Shuberts were appalled by Sigmund Romberg's score, disgusted by the book's unhappy ending, and incredulous that Romberg insisted on a chorus of men instead of the usual Broadway beauties. Fortunately, Romberg and his lawyer prevailed, forcing the Shuberts to stage an operetta that ran a record 608 performances and made them a fortune.            
   Dorothy Donnelly, who penned the lyrics, also adapted the book, which was based on the German play Old Heidelberg. Prince Karl Franz, studying in the quaint German University town of Heidelberg, falls in love with Kathie, a waitress at the Inn of the Three Golden Apples. But Karl's grandfather, the king, falls ill, and Karl must return home. For reasons of state, he is also forced to marry Princess Margaret, who is herself in love with a military captain. Years later, Karl returns to Heidelberg for one final goodbye with Kathie.              
   The Student Prince opened on Broadway in 1924, and toured the nation from 1925 to 1933. So popular was it that it received its first Broadway revival only five years after the end of its original run, in 1931. After another revival in 1943, it found a home again at New York City Opera in 1980. MGM filmed it twice, first as a silent with Ramon Navarro and Norma Shearer in 1927, then as a lavish Technicolor spectacular starring Edmund Purdom (lip-synching to Mario Lanza) and Ann Blyth in 1954. This hardy old warhorse remains as irresistible as ever. Romberg has never been toppled from his throne as king of that short-lived but delectable confection-the Broadway operetta.