cāraṇa, garbha- and bāhyadruti necessary for bandhana

na patati yadi ghanasatvaṃ garbhe no vā dravanti bījāni /
na ca bāhyadrutiyogastatkathamiha badhyate sūtaḥ // GRht_13.8 //

sūtabandhane hetūnāha netyādi // GRhtCM_13.8:1 //

yadi garbhe rasodare ghanasattvaṃ abhrakasāraṃ na patati na prāpnoti vā garbhe bījāni asminnadhyāye abhihitāni mākṣikakāntaśupbādīni yāvanno dravanti ca punarbāhyadrutistasyā yogo rase drutimepanaṃ na syāt tattasmāddhetoḥ sūta ihāsyāṃ kriyāyāmasatyāṃ kathaṃ badhyate ghanatvaṃ dhatte // GRhtCM_13.8:2 //

garbhadrutibāhyadrutibhyāṃ sūto badhyate niyatamityabhiprāyaḥ // GRhtCM_13.8:3 //