&NA;In five dogs with continent colostomies constructed according to a method described previously the dynamics of the “nipple valve” were studied electromanometrically by recording simultaneously the intracolonic pressure and the “withdrawal” pressure. A high‐pressure zone was recorded in the nipple valve and the length of the zone corresponded roughly to the anatomic nipple length. The maximal pressures in the high‐pressure zones varied considerably in different dogs as well as in the same animal from time to time. When the intraluminal pressure of the bowel was high, as occurs before emptying, the pressure in the high‐pressure zone was higher. After emptying, when the intraluminal pressure was low, the pressure in the high‐pressure zone diminished, but remained higher than the intraluminal pressure. The minimum pressure in the high‐pressure zone always exceeded that simultanously recorded in the bowel lumen. In acute experiments it was found that a nipple length of at least 2.5 cm was necessary for achieving continence for air.