Verse 8.3.1.13

yadveva diśyā upadadhāti | candāṃsi vai diśaḥ paśavo vai candāṃsyannam paśavo madhyam madhyamā citirmadhyatastadannaṃ dadhāti tā anantarhitāḥ svayamātṛṇāyā upadadhāti prāṇo vai svayamātṛṇānantarhitaṃ tatprāṇādannaṃ dadhātyuttarā uttaraṃ tatprāṇādannaṃ dadhāti retaḥsicorvelayā pṛṣṭayo vai retaḥsicau madhyamu pṛṣṭayo madhyata evāsminnetadannaṃ dadhāti sarvata upadadhāti sarvata evāsminnatadannaṃ dadhāti

Preview of English translation:

13. And, again, as to why he lays down the regionals. The regions, doubtless, are the metres, and the metres are animals, and animals are food, and the middlemost layer is the middle: he thus puts food in the middle (of the body). He places them so as not to be separated (by special bricks) from the naturally-perforated one; for the naturally-perforated one is the vital air: he thus places the food so as not to be separated from the vital air. Subsequently (to the central brick he lays them down): subsequently to (or upon) the vital air he thus places food. On the range of the Retahsic (he places them): the Retahsic being the ribs, and the ribs being the middle (of the body), he thus places the food in the middle of this (Agni’s body). On every side he places them: from everywhere he thus supplies him with food.

For a detailled translation, including proper diacritics and footnotes, go the full English translation.