251. Certain ā-roots, because of their peculiar exchanges with ī and i-forms, especially in forming the present stem, are given by the Hindu grammarians as roots ending in e or āi or o. Thus, from 2 dhā suck (dhe) come the present dháyati and participle and gerund dhītá, dhītvā́; the other forms are made from dhā, as dadhus, adhāt, dhāsyati, dhā́tave, dhāpayati. From 2 gā sing (gāi) come the present gā́yati, the participle and gerund gītá and gītvā́, and passive gīyáte, and the other forms from gā. From 3 dā cut (do) come the present dyáti and participle ditá or diná, and the other forms from dā. The irregularities of these roots will be treated below, under the various formations (see especially 761 d ff.).
252. By a process of abbreviation essentially akin with that of ar or ra to ṛ, the va (usually initial) of a number of roots becomes u, and the ya of a much smaller number becomes i, in certain verbal forms and derivatives. Thus, from vac comes uvā́ca, ucyā́sam, uktvā́, uktá, uktí, ukthá, etc.; from yaj come iyā́ja, ijyā́sam, iṣṭvā́, iṣṭá, íṣṭi, etc. See below, under the various formations.
a. To this change is given by European grammarians the name of samprasāraṇa, by adaptation of a term used in the native grammar.
253. A short a, of root or ending, is not infrequently lost between consonants in a weakened syllable: thus, in verb-forms, ghnánti, ápaptam, jagmús, jajñús, ájñata; in noun-forms, rā́jñe, rā́jñī.
254. Union-vowels. All the simple vowels come to assume in certain cases the aspect of union-vowels, or insertions between root or stem and ending of inflection or of derivation.
a. That character belongs oftenest to i, which is very widely used: 1. before the s of aorist and future and desiderative stems, as in ájīviṣam, jīviṣyā́mi, jíjīviṣāmi; 2. in tense-inflection, especially perfect, as jijīvimá; occasionally also present, as ániti, róditi; 3. in derivation, as jīvitá, khánitum, janitṛ́, rociṣṇú, etc. etc.
b. Long ī is used sometimes instead of short: thus, ágrahīṣam, grahīṣyā́mi; bravīti, vāvadīti; tarītṛ́, savītṛ́; it is also often introduced before s and t of the 2d and 3d sing. of verbs: thus, ā́sīs, ā́sīt.
c. For details respecting these, and the more irregular and sporadic occurrences of u- and a-vowels in the same character, see below.
Nasal Increment.
255. Both in roots and in endings, a distinction of stronger and weaker forms is very often made by the presence or absence of a nasal element, a nasal mute or anusvāra, before a following consonant. In general, the stronger form is doubtless the more original; but, in the present condition of the language, the nasal has come in great measure to seem, and to some extent also to be used, as an actually strengthening element, introduced under certain conditions in formative and inflective processes.
