How wide must the crack be? Beit Hillel says as long as it is filled by a plumb line, and Rabbi Yosi says, quoting Beit Hillel, it must be a handbreadth wide. Rabbi said, 'I am astonished if Rabbi Yosi said it must be a handbreadth. He only said this regarding an olive-sized portion of a corpse.' If the impurity is inside and the vessels are outside, even if the crack is only filled by a plumb line, it serves as a barrier. A se'ah measure overturned on the mouth of a barrel, or two domes placed one on top of the other, and a stone placed on top of the dome, bring impurity. A se'ah measure placed upright, a barrel placed upright, an inflated wineskin placed upright, a se'ah full of straw, a cushion full of feathers, or clothing full of handkerchiefs, two stones one on top of the other, or a dome on top of a stone, do not bring impurity. A dog that ate the flesh of a corpse and entered a house does not make the house impure, because anything swallowed by a person, an animal, a beast, or birds is pure.⁠a But if it vomits, the house becomes impure. If a corpse remains in the intestines until the living being survives for three days, from moment to moment, then it is considered alive. In the case of birds and fish, it is immediate. Rabbi Yehuda ben Beteira says, for fish it is immediate, but for birds, it is from moment to moment. Rabbi Eliezer says in the name of Rabbi Yehuda ben Beteira, both are from moment to moment.