In a series of lectures Arnim published the results of an inquiry into Plato's use of reply formulae. He was apparently unaware of the existence of Ritter's work, but though much of the ground which he covered was the same, his material did differ to some extent from his predecessor's. His definition of his sphere of operation was as follows: ‘Ad eas tantum formulas animum attendi quae sive separatim sive initio orationis positae nil nisi meram affirmationem continerent, eamque ipsis verbis expressam neque cohaerentem cum verbis antecedentibus interrogantis.’ The method of presentation, too, differed greatly from Ritter's, and an attempt has been made to preserve its form while at the same time compressing it as much as possible by collecting the statistics into tables (pp. 110–14).

Regarding the accuracy of this investigation, the difficulty of checking statistics of reply formulae owing to the numerous variations has already been mentioned (p. 55). Arnim's classification was less strict than Ritter's, which means that his figures for the same formula are usually higher, and while for the most part they appear to be fairly accurate, there are some disturbing errors.