Harnack followed the ecclesiastical authors without critically examining their assertions. He relied on them. If he had been aware of the fact that Irenaeus, Tertullian, Epiphanius could not have thought otherwise than they did without becoming heretic and that their opinion depended completely on their faith, he would have agreed that it made sense to take up the question once again and to handle the question with purely critical method.
Yet critical investigation stands against the assumptions of the ecclesiastical authors. It shows as we will see, that the Apostolicon is not a mutilation of the long edition but, on the contrary, that the long edition is nothing but a reworked and extended Apostolicon. In other words, the text reconstructed by Harnack is the genuine edition of the Paulina. It is the oldest version available to us.
Post and thanks to the poster (kenoma_ru) here: http://community.livejournal.com/gnosticism