239. The vrddhi-increment

The vṛddhi-increment is specifically Indian, and its occurrence is less frequent and regular. It is found—

a. In root and suffix-syllables, instead of guṇa: thus, stāúti from √stu, sákhāyam from sákhi, ánāiṣam from √nī, ákārṣam and kāráyati and kāryà from √kṛ (or kar), dātā́ram from dātṛ́ (or dātár).

b. Especially often, in initial syllables in secondary derivation: thus, mānasá from mánas, vāidyutá from vidyút, bhāumá from bhū́mi, pā́rthiva from pṛthivī́ (1204).

But—