COMMUNIO. – This is the antiphon sung by the choir in the Solemn Mass after the celebrant’s Communion; in all Masses it is simply read by the celebrant himself. In ancient times it was sung during the distribution of Communion to the faithful, interspersed with the verses of a psalm. Little by little, the psalm was shortened until it disappeared entirely, so that only the antiphon remained, in which some thought relating to the day or feast being celebrated is summarized; a vestige of the ancient practice has survived only in the Mass for the dead. In the Ambrosian liturgy it is called transitorium.
BIBL.: I. Schuster, Liber Sacramentorum, I, 3ª ed., Torino 1932, p. 100; III, ivi 1933, p. 70; G. Destefani, La Messa nella liturgia romana, ivi 1935, pp. 307, 751 ss. Filippo Oppenheim