Jaiminīya (Talavakāra) Brāhmaṇa 2-8.380

Prajāpati, indeed, is the Abhīvarta; creatures are the meters. / This Prajāpati goes depositing the embryo in creatures. / They chant on different [verses] with the same sāman; / they thus emit semen; / therefore, a single [male] deposits semen in many [females]. / There are the same verses thereafter, [but] a different sāman; / they thus bring forth the emitted semen; / therefore, a single [female] gives birth to many. / They chant on different [verses] with the same sāman; / for going on, they see different things. / There are the same verses thereafter, [but] a different sāman. / Which worlds they go ascending toward from here with the pragāthas, those they come descending back from yonder with the sāmans. / The verse is this world; the sāman is yonder [world]. / When going from here, they go holding on to the sāman, they go holding on to yonder world. / If they were to stop before the Viṣuvant, they would be cut off from yonder world. / When coming from yonder, they come holding on to the verse, they go holding on to this world. / If they were to stop before the days belonging to the twelve-day rite, they would be cut off from this world.

Once, on the farther side, they overturn the Abhīvarta.

Therefore embryos, when being born, turn around.

Formerly, indeed, before the fifth month, the Bārhata pragāthas were reached.

Having combined two meters, the Uṣṇih and the Triṣṭubh, they should complete five months.