The document popularly designated as the Bull Coena, or the Bull In Coena Domini, derives its name from the practice, which is of great antiquity in the Roman Church, of publishing annually, on Maundy Thursday, the anniversary of the institution of the Lord's Supper, thence called Dies Coena Domini, certain sentences of excommunication against the enemies of the Roman See and the Roman Church. The document containing these sentences being in the form of a Papal Bull or Letter Apostolic, is accordingly called the Bull Coena or In Coena. For the last two centuries and a half it has undergone no change, being republished from time to time by successive Popes without alteration or addition, and adopted into the body of the Roman Canon Law, some of the most important principles of which are contained in it. According to the usual manner of citing Papal Bulls by the initial words, the Bull in its present shape is called the Bull "Pastoralis Romani Pontificis" but there were other Bulls before it, which, on the same ground as this, viz., their publication on Maundy Thursday, were, in their time, the Bulls Coena, or In Coena. In fact the Bull Pastoralia is the latest edition of a series of Bulls issued at different times, and by different Pontiffs, for the excommunication of heretics, for the assertion and maintenance of the Ecclesiastical supremacy of the Roman Pontiff, and for other collateral purposes. The different excommunications which are now thrown together into one Bull, were originally scattered through a variety of Bulls, and by degrees incorporated with the Bull published annually on Maundy Thursday.