Agni is the one who is introduced by Manu, who is kindled by Manu; one requests him to rule at the present sacrifice, as he had done it for Manu, when he "offered the first oblation, with kindled fire, with his (attentive) heart and soul, along with the seven priests" to the gods (X, 63, 7).
1988, Hermann Oldenberg, Shridhar B. Shrotri, The Religion of the Veda, page 138