The movement of ova in the excised mouse oviduct was observed before and after straightening of the tube and after compression under a glass coverslip. Ciliated cells were present only in the ampulla, and produced a current from the bursa to the ampulla. However, movement of ova in the dilated section of the ampulla was seen to be due solely to contractions of the walls. In the isthmus ova were found only in one or two adjacent loops. These were dilated and showed segmental contractions, producing pendular movements of the ova. Peristaltic contractions were only seen in loops containing ova and in the isthmus near the ampulla-isthmus junction; this may present adovarian movement of ova. In vivo, most ova pass through the isthmus in 12 hr. The sphincters at the ampulla-isthmus and isthmouterine junctions retain the ova for 24 and 30 hr. respectively of the 72 hr. spent in the tube.