'The Yeomen of the Guard' has a serious plot, and at times lingers on the threshold of tragedy. Sullivan caught the altered spirit of his collaborator with perfect sympathy, and struck a note of romantic feeling unique in his career. With 'The Gondoliers' (1889) the scene brightened again, and merriment reigned supreme once more. Perhaps at times there was a suspicion of weariness in Mr. Gilbert's wit, and some of Sullivan's melodies had not all the old distinction of manner, but the piece was an incarnation of liveliness and gaiety, and its success rivalled the historic glories of 'The Mikado.' With 'The Gondoliers' came the first solution of continuity in the Gilbert and Sullivan partnership. Differences arose; Mr. Gilbert retired from the councils of the Savoy Theatre, and Sullivan had to look out for a new collaborator. He found one in Mr. Sydney Grundy, and their 'Haddon Hall' was produced in 1892. In spite of charming music, reflecting very gracefully the old English atmosphere of the story, its success was only moderate, and the world of music was much relieved to hear that the differences between Mr. Gilbert and the Savoy authorities had been adjusted, and that the two famous collaborators were to join forces once more. Unfortunately 'Utopia' (1893) echoed but faintly the magical harmonies of the past. The old enchantment was gone; the spell was shattered. Both collaborators seemed to have lost the clue that had so often led to triumph. Again they drifted apart, and Sullivan turned once more to his old friend, Sir Frank Burnand. Together they produced 'The Chieftain' (1894), a revised and enlarged version of their early indiscretion, 'The Contrabandista.' Success still held aloof, and for the last time Sullivan and Mr. Gilbert joined forces. In 'The Grand Duke' (1896) there were fitful gleams of the old splendour, notably in an amazing sham--Greek chorus, which no one but Sullivan could have written, but the piece could not for a moment be compared to even the weakest of the earlier operas. The fate of 'The Beauty Stone' (1898), written to a libretto by Messrs Pinero and Comyns Carr, was even more deplorable. Fortunately Sullivan's collaboration with Captain Basil Hood brought him an Indian summer of inspiration and success. 'The Rose of Persia' (1900), if not upon the level of his early masterpieces, contained better music than he had written since the days of 'The Gondoliers,' and at least one number--the marvellous Dervish quartet--that for sheer invention and musicianship could hardly be matched even in 'The Mikado' itself. There was a great deal of charming music, too, in 'The Emerald Isle' (1901), which Sullivan left unfinished at his death, and Mr. Edward German completed.