 Complete the following phrase:  Although much of Dargomyzhskys Rusalka is fairly conventional in musical form and style, its singular innovation for the history of Russian music in particular is the application of melodic recitative at certain points in the drama. This type of recitative consists of lyrical utterances which change continuously according to the dramatic situation, with likewise varied accompaniment in the orchestra. Dargomyzhsky was to apply this technique of vocal composition on a small scale in his songs and on a large scale in his final opera, 