Satapatha Brahmana Part II (SBE26), Julius Eggeling tr. , at sacred-texts.com
4:6:3:11. Now as to the manner of animal offerings. One may perform with the (ordinary) set of eleven victims. He seizes one for Agni as the first victim, and one for Varuna (as the last); then again one for Agni.: in this way let him perform with the set of eleven victims 2.
4:6:3:22. Or one may day after day seize a victim for Indra and Agni; for all the gods are Agni, since in Agni offering is made to all the deities; and Indra is the deity of the sacrifice: thus he neither offends any of the deities, nor does he offend him who is the deity of the sacrifice.
4:6:3:33. Then as to the manner (of animal offering) in accordance with the Stoma 3. At the Agnishtoma
let him seize a (victim) for Agni; for it is befitting that at the Agnishtoma ('Agni's praise') he should seize a victim for Agni. If it be an Ukthya sacrifice, let him seize as the second (victim) one for Indra and Agni, for the hymns (uktha) 1 belong to Indra and Agni. If it be a Shodasin sacrifice, let him seize as the third (victim) one for Indra; for the Shodasin (graha) is Indra. If it be an Atirâtra, let him seize as the fourth (victim) one for Sarasvatî; for Sarasvatî is Vâk (speech), and Vâk is a female, and so is râtri (fem., 'night') female. Thus he duly distinguishes between the sacrificial performances. Such are the three manners (of animal offering): he may perform in whichever manner he pleases. Two victims must needs be seized,--for Sûrya he seizes the second en the Vishuvant day, and for Pragâpati at the Mahâvrata.
428:2 See III, 9, 1, 5 seq. He is to sacrifice one victim each day, and if after the eleventh day, the performance is to go on (as at the Dvâdasâha), he is to begin anew with the first victim of the ekâdasinî. According to the Kânva text and Kâty. XII, 6, 17 he is on such an odd day to immolate all the remaining victims of the set of eleven. Thus on the last (twelfth) day of the Dvâdasâha--the Udayanîya Atirâtra--he would have to sacrifice the entire set of eleven victims.
428:3 I.e. the particular form of the Gyotishtoma, which is being performed.
429:1 That is, the hymns of the Rig-veda, the single collections of which begin with the hymns to Agni, followed by those to Indra. The 'ukthâni' here can scarcely refer to the three additional sastras of the Ukthya sacrifice, as they are composed of hymns to Indra-Varuna, Indra-Brihaspati, and Indra-Vishnu respectively. Âsv. Sr. VI, 1; Ait. Br. III, 50. Cp. IV, 2, 5, 14.