The source would seem to be the 1914 translation by H. Rackham, which I found browsing on openlibrary.org (specifically http://openlibrary.org/books/OL6568594M/De_finibus_bonorum_et_malorum). Check the .pdf version: on pages 35-36 of the original printing, in Book I, section 32, the word “dolorem” is split across two pages, with the result the professor cited.
Just so everybody’s on the same page, this refers to the column What does the filler text “lorem ipsum” mean?
I don’t think that the pdf cited means what Steve thinks it means, though. No one doubted that it was from Cicero, so finding a source that contains Cicero is no big deal.
What the professor was looking for was its use as dummy text. The pdf has the full Latin text on verso with the English translation on recto. Not the same thing at all.
The fake text has dropped words. The pdf has the full text. If you found a Cicero that was printed with the proper words dropped then that might be the source. This is just Cicero, nothing more.
I just saw the very good documentary Bill Cunningham New York, about the NYT’s longtime “street fashion” photographer, who’s now 82 but just as hard-working and active as ever. There were several scenes of him electronically composing his newspaper page layout with the help of a younger staffer, and you can clearly see the filler text is “lorem ipsum” etc.