My attention having been drawn to the fact that Harnack dated the Ignatian epistles to the 130s (as have I), I thought I might read what he had to say (Adolf von Harnack, “Lightfoot on the Ignatian Epistles. II. Genuineness and Date of the Epistles” The Expositor third series 3.3 (March 1886), 175-192. This is the third part of an extended review of Lightfoot.)
Interesting though this was, my attention was more taken by Frederic Henry Chase, “Note on The Teaching of the Twelve Apostles Chapter xi,” The Expositor third series 3.4 (April 1886), 319-320. Here Chase suggests emending εἰς μυστήριον κοσμικὸν ἐκκλησίας to εἰς μαρτύριον κόσμιον ἐκκλησίας.
I will admit that I have never seen reference to Chase’s conjecture, and also that I find it very attractive. I need say no more, but commend those interested to read Chase’s argument in support.