These compositions are what we would call part songs and they are usually constructed in simple four-part harmony, without fugato passages or imitations. When imitations do appear, they are secondary and do not deal with the fundamental melodic ideas of the song. Nothing corresponding to subject and answer is found in these works. If we turn from a frottola to a motet by the same composer, we meet at once the device of canonic imitation and with it a clearly different artistic purpose. These composers evidently did not expect the people to be such accomplished musicians as the singers of the trained choirs. "Indeed, the frottola descended by an extremely easy transition to the villanelle, a still more popular form of composition and one marked by even less relationship to the counterpoint of the low countries. At the time of the full development of the madrigal the serious and humorous elements which dwelt together in the frottola separated completely. The purely sentimental and idealistic frottola became the madrigal; the clearly humorous frottola became the villanelle. When these two clearly differentiated species were firmly established, the frottola disappeared. "The madrigal existed as early as the fourteenth century, but its general spread dates from the time of Adrian Willaert (1480-1562). The madrigal was originally a pastoral song, but the form came to be utilized for the expression of varied sentiments and it was treated with a musicianship which advanced it toward the more stately condition of the 'durchcomponirt' motet. In the villanelle the influence of the strophic folk song is clearly perceptible. The frottola to a certain extent stood in the middle. It is sung verse by verse, but its musical scheme is almost always conceived in a much broader spirit than that of the villanelle and gives to it almost the appearance of a durchcomponirt work. But the systematic repetition of certain couplets in the manner of a refrain occasions the recurrence of whole musical periods. Thus does the frottola acquire from its text that architectural shape which places it in marked contrast to the swift-paced and fluid contrapuntal chanson of the Netherlanders. Its rhythm and accents are arranged not by the needs of contrapuntal development, but by the meter of the line and the accent of the Italian tongue. This appears most prominently in the upper voice part, where often the controlling melody seems ready to break quite through in pure song style, but only partly succeeds. In the texture of the voices all kinds of imitations appear, but only subordinated and in very modest setting.