[934.] (a.) With the present stem in a nasalized root followed by -o|e- ([831]).

findō, split apartfindere-fidī, rarely fidīfissus
scindō, rendscindere-scidī, rarely scidīscissus

[935.] (b.) With the present stem in -lo|e- ([833]).

per-cellō, knock downper-cellereper-culīper-culsus

[936.] (2 a.) The following verbs in -ere have a perfect stem consisting of a consonant root with a long vowel ([862]), and the perfect participle, when used, in -tus:

[937.] (a.) With the present stem in -o|e- ([829]).

agō, driveagereēgīāctus

Real compounds have i for a in the present system: as, ab-igō, ab-igere, ab-ēgī, ab-āctus; but per-agō retains a. cōgō and dēgō are contracted: cōgō, cōgere, co-ēgī, co-āctus; dēgō, dēgere, ——, ——.

emō, take, buyemereēmīemptus

co-emō retains e in the present system, and usually inter-emō and per-emō; other compounds have -imō. For cōmō, dēmō, prōmō, and sūmō, see [952].