एक तद्धिते च

As एकस्या आगतं = एकरूप्यम्, एकमयम्, एकस्या भावः = एकत्वम्, एकता ॥ So also एकस्याः क्षीरं = एकक्षीरम्, एकदुग्धम् ॥ The shortening takes place of the Feminine word एका, having the affix आ ॥ When एक is an adjective (गुणवचन) then the above forms could be evolved by the help of the rules of masculation, such as 6.3.35, i.e. when एक means the numeral one. But when it means 'alone', then those rules will not apply. The word एक is exhibited in the sutra without any case-affix as a Chhandas irregularity. The examples given are of एका in the feminine which alone can be shortened, and not of एक whose final is already short. Nor can the rule of shortening be applied to ए of एक, for the rule applies to the final letter, and not to a vowel situeated in the body of a word.,