He then went to Alexandria, where he developed his doctrine, a modified Marcionism, which (according to Tertullian) admitted that Christ possessed true human flesh but continued to deny the nativity (Tertullian, Adversus Marcionem III.1.1).
Apelles wrote a book entitled Syllogisms -- 'reasonings' -- though the word itself suggests that Apelles may have intended to oppose Marcion's 'Antitheses', which set the Old Testament and the New Testament against each other.
He is last heard of in Rome in the last portion of the second century (Eusebius, Ecclesiastical History).
His followers, the 'Apelliacos' or Apelleasts, are likewise unknown. Tertullian wrote a tract against them which has not survived. Ambrose of Milan in the 4th century directs some of his comments in his 'De paradiso' (On the Garden of Eden) against this sect, but whether the sect was still active or whether Ambrose had merely copied another now lost work of Tertullian on the same subject is unknown.
Tertullian mentions a teaching of this sect that flesh was constructed for seduced souls by a certain 'fiery prince of evil' (De Carne Christi 8 and De Anima 23). This seems related to the sort of gnostic ideas held by Basilides or Valentinus. Later Marcionite ideas described by the Armenian Eznik (or Yeznik Koghbatsi) seem similar to this.