If anyone could help me with finding a translation of the text, I would greatly appreciate it. I found one of his works with an English translation ("Introduction to the New Testament"); however, I have not found one for this article. I apologize if this is the incorrect subreddit to post my question: I am not certain of where else to post it. Thank you so much for your assistance.
Here is a link to the version I found, if that helps: http://books.google.com/books?hl=en&lr=&id=-SI2AQAAMAAJ&oi=fnd&pg=PA409&dq=theodor+Zahn&ots=9L3-8S-E1u&sig=sqPJnobhwdHLRxuZPOVeULUPgPo#v=onepage&q=theodor%20Zahn&f=false
The only books of his in English are his introduction to the New Testament and his work on the Apostle's Creed
If you are into older German scholarship on Marcion translated into English (frankly, who isn't) then see: Harnack, Adolf von, 1851-1930. Marcion, The Gospel of the Alien God Publisher: Durham, N.C. : Labyrinth Press.
Here are some titles (in English) for you to check out:
Foakes-Jackson, F. J. (Frederick John), 1855-1941. Title: Christian difficulties in the second and twentieth centuries : a study of Marcion and his relation to modern thought /
Deakle, David Wayne, 1955. Title: The Fathers against Marcionism : a study of the methods and motives in the developing Patristic anti-Marcionite polemic /
Wilson, Robert Smith. Title: Marcion : a study of a second-century heretic / Publisher: London : James Clarke, [1932]
Blackman, Edwin Cyril. Title: Marcion and his influence / Publisher: London : S.P.C.K., 1948.
Knox, John, 1900-1990. Title: Marcion and the New Testament : an essay in the early history of the canon / Publisher: Chicago : University of Chicago Press, 1942.
Hoffmann, R. Joseph. Title: Marcion, on the restitution of Christianity : an essay on the development of radical Paulinist theology in the second century / Publisher: Chico, Ca. : Scholars Press, [1984]
All the best in your research.
It's never been translated to English.
But it's obviously in German...and honestly, minus some technical terms, Google Translate handles German well, if you don't know it.
Also, from my understanding, a lot of Zahn's focus on Marcion in that book is simply a compilation of Marcionic quotations in an attempt to reconstruct Marcion's gospel. Surely you can find this information elsewhere in more recent (English) secondary sources.