How so? [If] a corpse is outside, and its hair is inside, the house becomes tamei. A bone has on it an olive-sized piece of flesh. If part of this bone was brought under the roof of a house, [the contents of the house] become tamei. There are two bones, each of which has on it half an olive’s size piece of flesh. [If] part of [each bone] was brought under the roof of a house, [the contents of the house] become tamei. [If they were] attached by man, [the house] remains tahor, because whatever is attached by man is not considered an [inherent] attachment.

What qualifies as ‘‘death blood’’? An eighth [of a log of blood] flowed out of a dy-ing person while he was still alive, and an eighth [flowed out] after he died. These are the words of R’ Akiva. R’ Yishmael says: A quarter [-log of blood that flowed out] while [the person] was alive and a quarter [-log that flowed out] after his death [were combined, and from this mixture] a quarter [-log] was taken. R’ Eliezer the son of R’ Yehudah says: Both of these are like water. What is ‘‘death blood’’? When there is a hanged person whose blood was flowing out and a quarter [-log] of blood was found beneath him, [the blood] is tamei. But if a corpse’s blood was dripping, and a quarter-log of blood was found underneath it, [the blood] is tahor. R’ Yehudah says: Not so; rather, that which flows out is tahor, and that which drips is tamei.

An olive-sized piece of corpse [in a room] must have an opening of one hand-breadth and a [whole] corpse must have an opening of four handbreadths to prevent tumah from spreading to the [other] openings. But to allow tumah to spread, one [square] handbreadth [suffices]. [If it is] larger than the volume of an olive, it is treated as a [whole] corpse. R’ Yose says: A spinal column and skull are treated like a [whole] corpse.

[A cavity] one handbreadth by one handbreadth squared that is one handbreadth high conveys tumah and acts as a barrier against tumah. How so? [In the case of] a sewer beneath a house that contains a [cubic] handbreadth and has an outlet of a [square] handbreadth — [if there is] tumah in-side [the sewer], the house remains tahor; [if there is] tumah in the house, whatever is inside [the sewer] remains tahor, because it is the way of the tumah to exit, but it is not its way to enter. [In the case where] the sewer contains a [cubic] handbreadth and its outlet is smaller than a [square] handbreadth — [if there is] tumah inside [the sewer], the house becomes tamei; [if there is] tumah in the house, whatever is inside [the sewer] remains tahor, because it is the way of tumah to exit, but it is not the way of tumah to enter. [In the case where the sewer is] smaller than a [cubic] handbreadth and its outlet is smaller than a [square] handbreadth — [if there is] tumah inside [the sewer], the house becomes tamei; [if there is] tumah in the house, whatever is inside [the sewer] becomes tamei. [This law is true] whether the hole was hollowed out by water, by small ani-mals, or by erosion, and [is also true if it is formed by] a pile of boulders or a stack of beams. R’ Yehudah says: Any roof that is not man made is not considered an ohel. However, he agrees with respect to crags and projecting rock formations [that they are considered ohalim].