[If] part of the tumah is in the house and part of it is opposite the skylight, the house becomes tamei, and whatever is opposite the tumah [also] becomes tamei; these are the words of R’ Meir. R’ Yehudah says: The house becomes tamei, but whatever is opposite the skylight remains tahor. R’ Yose says: If the tumah is large enough that when divided in half it can contaminate both the house and whatever is opposite the tumah, [they are both] tamei; if not, the house becomes tamei, [and] whatever is opposite the tumah is tahor.