AMBROSIAN CHANT, a general term applying to the particular type of liturgical music associated with the name of St. Ambrose, bishop of Milan, and introduced by him into the churches of his diocese. As to what it amounted to precisely considerable doubt exists, but it is generally agreed that St. Ambrose transplanted the singing of the Hallelujah and antiphonal singing from Greece into Italy, while he is also looked upon as the originator of the Responses. Otherwise the Ambrosian Chant seems to have had much in common with the Gregorian, which is regarded by some as having been merely a comprehensive revision of the then existing (7th century) ritual song, based on Ambrosian practice, although doubtless including much which had been added after St. Ambrose's death (397) • St. Ambrose was also responsible for the introduction of hymn-singing, as dis tinguished from the chanting of the Psalms and the canticles, as an essential feature of the music of public worship in the Western Church, and wrote many hymns himself, though the number of genuine examples to be ascribed to him is less than has sometimes been stated. (See also AMBROSE, SAINT ; GREGORY [Pope] ; and PLAIN-SONG.)