When a descendant of the description denoted by yuvan -- jīvati tu vaṃśye yuvā [[4.1.163]], is intended to be expressed, a new affix is attached, only after that what already ends with an affix marking a descendant as low at least as a grandson (gotra) but in the feminine the word is not termed yuvan and no new affix is added.,
This is also a niyama or restrictive rule. Thus the Yuvan of गार्ग्य is गार्ग्यायणः 4.1.101. Similarly वात्स्यायणः, दाक्षायणः, प्लाक्षायणः, औपगविः, नाडायनिः ॥
Why do we say \but in the Feminine the word is not termed Yuvan\? Observe दाक्षी which is the feminine of दाक्षिः (Gotra) as well as of दाक्षायणः (Yuvan). Similarly प्लाक्षी feminine of प्लाक्षिः and प्लाक्षायणः ॥ In short, Yuvan affixes are not added in the feminine. If it is intended to denote a feminine descendant of the kind Yuvan, the feminine word formed by Gotra affix will denote such a descendant also.
What is here prohibited i. e. is the term Gotra superseded by the term Yuvan? If it is a niyama rule, there will be no niyama with regard to the feminine, as the prohibition is contained in the same sentence. Therefore in the feminine, the Yuvan affix will not get the designation of Gotra, because Gotra-name is debarred by Yuvan Name. Therefore the sutra should be divided in two, e. g. गोत्राद् यूनि प्रत्ययो भवति (2) ततोऽस्त्रियाम् ॥ (1) After a Gotra formed word a new affix is added in denoting a Yuvan descendant, (2) but not so in the feminine. In fact the name Yuvan is prohibited in the feminine, therefore, the feminine will be known Gotra always and never by Yuvan.,