In the case of the verb gṛ preceded by anu and prati and meaning 'to encourage by repeating', the person who was the agent of the prior action, which is repeated, is called sampradāna,
The phrase purvasya karta of the last is to be read into this aphorism. As होत्रे ऽनुगृणाति. They encourage the Hotri, i.e. the Hotri priest invokes first, the others then follow him in invocation and by so doing encourage him. The word अनुगरः and प्रतिगरः mean encouraging the invoker.,