c. From tense-stems the examples are far fewer, but not unknown: thus, from present-stems, occasional derivatives in a (1148 j), ā (1149 d, e), ana (1150 n), i (1155 d), u (1178 f), ta (1176 e), tu (1161 d), uka (1180 d), tra (1185 e), ti (1157 g), vin (or in: 1232 b, 1183 a); from stems in a s apparently of aoristic character (besides infinitives and gerundives), occasional derivatives in a (1148 j), ana (1150 j), ani (1159 b), an (1160 a), āna (1175), as (1151 c), ī (1156 b), iṣṭha (1184 a), u (1178 f), us (1154 a), tṛ (1182 e), in (1183 a).
1141. The primary suffixes are added also to roots as compounded with the verbal prefixes.
a. Whatever, namely, may have been originally and strictly the mode of production of the derivatives with prefixes, it is throughout the recorded life of the language as if the root and its prefix or prefixes constituted a unity, from which a derivative is formed in the same manner as from the simple root, with that modification of the radical meaning which appears also in the proper verbal forms as compounded with the same prefixes.
b. Not derivatives of every kind are thus made; but, in the main, those classes which have most of the verbal force, or which are most akin in value with infinitives and participles.
c. The occurrence of such derivatives with prefixes, and their accent, will be noted under each suffix below. They are chiefly (in nearly the order of their comparative frequency), besides root-stems, those in a, in ana, in ti, in tar and tra, and in in, ya, van and man, i and u, as, and a few others.
1142. The suffixes of both classes are sometimes joined to their primitives by a preceding union-vowel — that is to say, by one which wears that aspect, and, in our ignorance or uncertainty as to its real origin, may most conveniently and safely be called by that name. The line between these vowels and those deserving to be ranked as of organic suffixal character cannot be sharply drawn.
Each of the two great classes will now be taken up by itself, for more particular consideration.
A. Primary Derivatives.
1143. Form of root. The form of root to which a primary suffix is added is liable to more or less variation. Thus:
a. By far the most frequent is a strengthening change, by guṇa- or vṛddhi-increment. The former may occur under all circumstances (except, of course, where guṇa-change is in general forbidden: 235, 240): thus, véda from √vid, móda from √mud, várdha from √vṛdh;
