measure comes the present-stem मिमा mimā, but the perfect-stem ममा mamā; and so on.
a. Irregularities of roots with initial consonants will be given below, 784.
783. For roots beginning with a vowel, the rules of reduplication are these:
a. A root with initial अ a before a single final consonant repeats the अ a, which then fuses with the radical vowel to आ ā (throughout the whole inflection): thus, आद् ād from √अद् ad eat; and in like manner आज् āj, आन् ān, आस् ās, आह् āh. The root ऋ ṛ forms likewise throughout आर् ār (as if from अर् ar).
b. A root with इ i or उ u before a single final consonant follows the same analogy, except in the strong forms (sing. act.); here the vowel of the radical syllable has guṇa, becoming ए e or ओ o; and before this, the reduplicating vowel maintains its independent form, and is separated from the radical syllable by its own semivowel: thus, from √इष् iṣ comes ईष् īṣ in weak forms, but इयेष् iyeṣ in strong; from √उच् uc, in like manner, come ऊच् ūc and उवोच् uvoc. The root इ i, a single vowel, also falls under this rule, and forms ईय् īy (y added before a vowel) and इये iye.
c. Roots which begin with vowels long by nature or by position do not in general make a perfect-system, but use instead a periphrastic formation, in which the perfect tense of an auxiliary verb is added to the accusative of a verbal noun (see below, chap. XV.: 1070 ff.).
d. To this rule, however, √āp obtain (probably originally ap: 1087 f) constitutes an exception, making the constant perfect-stem āp (as if from ap: above, a). Also are met with īḍé (RV.) and īḍire from √īḍ, and īriré (V.) from √īr.
e. For the peculiar reduplication ān, belonging to certain roots with initial vowels, see below, 788.
784. A number of roots beginning with va and ending with a single consonant, which in various of their verbal forms and derivatives abbreviate the va to u, do it also in the perfect, and are treated like roots with initial u (above, 783 b), except that they retain
