607. The Hindu grammarians reckon a tenth class or cur-class, having a class-sign áya added to a strengthened root (thus, coráya from √cur), and an inflection like that of the other a-stems. Since, however, this stem is not limited to the present-system, but extends also into the rest of the conjugation — while it also has to a great extent a causative value, and may be formed in that value from a large number of roots — it will be best treated in full along with the derivative conjugations (chap. XIV., 1041 ff.).
608. A small number of roots add in the present-system a ch, or substitute a ch for their final consonant, and form a stem ending in cha or chá, which is then inflected like any a-stem. This is historically, doubtless, a true class-sign, analogous with the rest; but the verbs showing it are so few, and in formation so irregular, that they are not well to be put together into a class, but may best be treated as special cases falling under the other classes.
a. Roots adding ch are ṛ and yu, which make the stems ṛcchá and yúccha.
b. Roots substituting ch for their final are iṣ, uṣ (or vas shine), gam, yam, which make the stems icchá, ucchá, gáccha, yáccha.
c. Of the so-called roots ending in ch, several are more or less clearly stems, whose use has been extended from the present to other systems of tenses.
609. Roots are not wholly limited, even in the later language, to one mode of formation of their present-stem, but are sometimes reckoned as belonging to two or more different conjugation-classes. And such variety of formation is especially frequent in the Veda, being exhibited by a considerable proportion of the roots there occurring; already in the Brāhmaṇas, however, a condition is reached nearly agreeing in this respect with the classical language. The different present-formations sometimes have differences of meaning; yet not more important ones than are often found belonging to the same formation, nor of a kind to show clearly a difference of value as originally belonging to the separate classes of presents. If anything of this kind is to be established, it must be from the derivative conjugations, which are separated by no fixed line from the present-systems.
610. We take up now the different classes, in the order in which they have been arranged above, to describe more in detail, and with illustration, the formation of their present-systems, and to notice the irregularities belonging under each class.
I. Root-class (second, ad-class).
611. In this class there is no class-sign; the root itself is also present-stem, and to it are added directly the per-
