These convey tumah via touch or carrying, but do not convey tumah via ohel: a bone the size of a barleycorn; the land of the nations; a field in which a grave was plowed over; a limb [severed] from a corpse or a limb [severed] from a living body that is lacking sufficient flesh [to heal]; [and] a spine and a skull that are incomplete. How much is considered ‘‘missing’’ in the spine [for it to be considered incom-plete]? Beis Shammai says: Two vertebrae. But Beis Hillel says: Even one vertebra. And of the skull? Beis Shammai says: As [large as the hole] made by a gimlet. But Beis Hillel says: An amount which, if removed from a living person, would cause him to die. Which gimlet are they referring to? The small one used by physicians — these are the words of R’ Meir. But the Sages say: The large gimlet of the [Temple] chamber.