c. Not infrequently, the initial s, usually altered after a certain prefix, retains the altered sibilant even after an interposed a of augment or reduplication: thus, aty aṣṭhāt, abhy aṣṭhām, pary aṣasvajat, vy aṣahanta, ny aṣadāma, nir aṣṭhāpayan, abhy aṣiñcan, vy aṣṭabhnāt; vi taṣṭhe, vi taṣṭhire.
d. Much more anomalous is the occasional alteration of initial radical s after an a-element of a prefix. Such cases are ava ṣṭambh (against ni stambh and prati stambh) and (according to the grammarians) ava ṣvan.
186. In other compounds, the final alterant vowel of the first member not infrequently (especially in the Veda) lingualizes the initial s of the second: for example, yudhiṣṭhira, pitṛṣvasṛ, goṣṭhá, agniṣṭomá, anuṣṭúbh, tríṣaṁdhi, diviṣád, parameṣṭhín, abhiṣená, pitṛṣád, puruṣṭutá.
a. A very few cases occur of the same alteration after an a-element: thus, saṣtúbh, avaṣṭambha, savyaṣṭhā́, apāṣṭhā́, upaṣṭút; also √sah, when its final, by 147, becomes ṭ: thus, satrāṣā́ṭ (but satrāsā́ham).
187. The final s of the first member of a compound often becomes ṣ after an alterant vowel: thus, the s of a prepositional prefix, as niṣṣídhvan, duṣṭára (for duṣṣtára), āvíṣkṛta; and, regularly, a s retained instead of being converted to visarga before a labial or guttural mute (171 a), as haviṣpā́, jyotiṣkṛ́t; tapuṣpā́.
188. Once more, in the Veda, the same alteration, both of an initial and of a final s, is not infrequent even between the words composing a sentence. The cases are detailed in the Prātiçākhya belonging to each text, and are of very various character. Thus:
a. The initial s, especially of particles: as ū ṣú, hí ṣma, kám u ṣvít; — also of pronouns: as hí ṣáḥ; — of verb-forms, especially from √as: as hí ṣṭhá, diví ṣṭha; — and in other scattering cases: as u ṣṭuhi, nū́ ṣṭhirám, trī́ ṣadhásthā, ádhi ṣṇóḥ, nákiḥ ṣáḥ, yájuḥ ṣkannám, agníḥ ṣṭave.
b. A final s, oftenest before pronouns (especially toneless ones): as agníṣ ṭvā, níṣ ṭe, īyúṣ ṭé, çúciṣ ṭvám, sádhiṣ ṭáva; — but also in other cases, and wherever a final s is preserved, instead of being turned into visarga, before a guttural or labial (171): as tríṣ pūtvā́, ā́yuṣ kṛṇotu, vā́stoṣ pátiḥ, dyāúṣ pitā́, víbhiṣ pátāt.
Conversion of न् n to ण् ṇ.
189. The dental nasal न् n, when immediately followed by a vowel or by न् n or म् m or य् y or व् v, is turned into the lingual ण् ṇ if preceded in the same word by the
