SB 6.18.6
retah sisicatuh kumbhe
urvasyah sannidhau drutam
revatyam mitra utsargam
aristam pippalam vyadhat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Upon seeing Urvasi, the celestial society girl, both Mitra and Varuna discharged semen, which they preserved in an earthen pot. The two sons Agastya and Vasistha later appeared from that pot, and they are therefore the common sons of Mitra and Varuna. Mitra begot three sons in the womb of his wife, whose name was Revati. Their names were Utsarga, Arista and Pippala.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Modern science is trying to generate living entities in test tubes by processing semen, but even long, long ago it was possible for semen kept in a pot to develop into a child.