The Apostolic Tradition of Hippolytus Translated into...

The account in Acts 6 was generally interpreted as limiting the number of deacons in any place to seven, far too few for effective service in large churches. So each deacon was given an assistant to “serve” him; 85 compare chapter 30. But even this was inadequate in very large communities, and at Rome ca. 250 the seven deacons and their subdeacons were further assisted by forty-two acolytes (“followers”).[197] The subdiaconate eventually became a major order and it is so treated in the Constitutions and the Testament.