Long ī is substituted for the vowel of the roots 1. ghrā and 2. dhmā in the Intensive.,
As जेघ्रीयते, देध्मीयते ॥ The long ई is for the sake of the subsequent sutra, short इ would have, by 7.4.25, given the same forms also.,
ई घ्रा-ध्मोः
Adhyāya 7 · Pāda 4 · Rule 31