a. There is in RV. a considerable number of cases (some thirty) in which the pada-text gives unnecessarily, and probably wrongly, an independent accent to a prefix before an accented verb (or other prefix): resolving, for example, ā́rūhat into ā́ áruhat, vyácet into ví ácet, abhyávarṣīt into abhí ávarṣīt, vyā́sarat into ví ā́ asarat (instead of ā-áruhat etc.).
1085. In combination with the non-personal parts of the verb-system — with participles, infinitives, and gerunds — the general rule is that the prefix loses its accent, in favor of the other member of the compound. But the prefix instead has sometimes the accent: namely, when combined —
a. with the passive participle in ta or na: thus, páreta gone forth; antárhita concealed; ávapanna fallen; sámpūrṇa complete (cf. 1284).
b. But some exceptions to this rule are met with: e. g., in RV., nicitá, niṣkṛtá, praçastá, niṣattá, etc.; in AV., apakrītá.
c. with the infinitive in tu (972), in all its cases: thus, sáṁhartum to collect; ápidhātave to cover up; ávagantos of descending. The doubly accented dative in tavāí retains its final accent, but throws the other back upon the prefix: thus, ánvetavāí for following; ápabhartavāí for carrying off.
1086. The closeness of combination between the root and the prefix is indicated not only by their unity of accent, but also by the euphonic rules (e. g. 185, 192), which allow the mutual adaptations of the two to be made to some extent as if they were parts of a unitary word.
1087. A few special irregularities call for notice:
a. In the later language, api, adhi, and ava, in connection with certain roots and their derivatives, sometimes lose the initial vowel: namely, api with nah and dhā, adhi with sthā, ava with gāh etc.: e. g. pinaddha, pihita, dhiṣṭhita, vagāhya, vataṅsa, vadānya, vaṣṭabhya, vamajjana, vekṣaṇa, valepana. In the Veda, on the other hand, iṣ is in a few cases found instead (apparently) of nis with √kṛ.
b. The final vowel of a prefix, especially an i, is (oftenest in the older language) sometimes lengthened, especially in derivative words: e. g. pratīkāra, nīvṛt, parīhāra, vīrúdh, adhīvāsá, ápīvṛta, abhīvartá; anūrúdh; avāyatī́, prāvṛ́ṣ, úpāvasu. In the Veda, the initial of anu is sometimes lengthened after negative an: e. g. anānudá, anānukṛtyá.
c. In combination with √i go, the prefixes parā, pari, and pra sometimes change their r to l. In this way is formed a kind of derivative stem palāy flee, inflected according to the a-class, in middle voice, which is not uncommon from the Brāhmaṇas down, and has so lost the consciousness of its origin that it sometimes takes the augment prefixed: thus, apalāyiṣṭhās (ÇÇS.), apalāyata (R.), apalāyanta (MBh.); it makes