Discusses accentuation of prepositions when they are retracted (παρέλκει): they do not alternate as in the cited example, and prepositions that function as verbs become heavy/stressed, with supporting examples.
* Ὅταν παρέλκῃ ἡ πρόθεσις, οὐ ποιεῖται ἐναλλαγὴν ὡς ἐν τῷ «τοὺς δ´ ἄρ´ ὑπὸ τρόμος εἷλεν» (Ε 862) βαρυτονητέον τὴν ὑπό· παρέλκεται γάρ. Καὶ πᾶσα δὲ πρόθεσις ῥῆμα σημαίνουσα βαρύνεται «ἔνθ´ ἔνι μὲν φιλότης (Ξ 216) »πάρα δ´ ἀνήρ, ὃς καταθήσει« (π 45).
Whenever the preposition is parenthetic, it does not undergo alternation, as in «τοὺς δ´ ἄρ´ ὑπὸ τρόμος εἷλεν» (Ε 862): one must accent ὑπό with a grave; for it is parenthetic. And every preposition that signifies a verb is accented with a grave: «ἔνθ´ ἔνι μὲν φιλότης (Ξ 216)»; «πάρα δ´ ἀνήρ, ὃς καταθήσει» (π 45).