<Tr> <Td> </Td> <Td> Loquetur Dominus, Introit for Week XXXIV of Ordinary Time Example of antiphonal psalmody in Gregorian chant De profundis, tract for the Requiem Mass Example of responsorial psalmody in Gregorian chant </Td> </Tr> <Tr> <Td_colspan="2"> Problems playing these files? See media help . </Td> </Tr> <P> Antiphonal chants such as the Introit, and Communion originally referred to chants in which two choirs sang in alternation, one choir singing verses of a psalm, the other singing a refrain called an antiphon . Over time, the verses were reduced in number, usually to just one psalm verse and the doxology, or even omitted entirely . Antiphonal chants reflect their ancient origins as elaborate recitatives through the reciting tones in their melodies . Ordinary chants, such as the Kyrie and Gloria, are not considered antiphonal chants, although they are often performed in antiphonal style . </P> <P> Responsorial chants such as the Gradual, Alleluia, Offertory, and the Office Responsories originally consisted of a refrain called a respond sung by a choir, alternating with psalm verses sung by a soloist . Responsorial chants are often composed of an amalgamation of various stock musical phrases, pieced together in a practice called centonization . Tracts are melismatic settings of psalm verses and use frequent recurring cadences and they are strongly centonized . </P>

Who is the pope for whom a system of chant was named and what texture was it always