The ninth perek (=chapter) of Masechet Hullin begins on today’s daf (=page). Entitled haOr ve-haRotev – “the skin and the meat juice,” this perek does not belong in Masechet Hullin, based on its contents. In fact, the topics covered in this chapter actually relate to issues of tumah ve-taharah – ritual purity and defilement – and would be most appropriately discussed in one of the tractates in Seder Taharot (the Order of Purity). Nevertheless, it is included in Masechet Hullinsince the topics that appear here are practically related to issues that are clarified in this tractate, since activities such as ritual slaughter, removing the animal’s hide and cutting the animal apart all raise potential issues of ritual defilement.
All food items that become ritually defiled by contact with a dead body can potentially defile other food and drink (this is referred to as tum’at okhlin), but only if they are the size of an egg. The Mishnah teaches that in the event that meat is not of sufficient size, it can be supplemented by other parts of the animal that are not ordinarily considered food. Thus, if the meat is the size of an egg if it is supplemented by the animal’s skin or solidified meat juice or bones, sinews, horns or hooves, then it will be susceptible to ritual defilement and it will defile other food or drink, as well.
A different type of ritual defilement discussed in the Mishnah is tum’at neveilah. A neveilah is an animal that was killed by a predator or died on its own. Such an animal is ritually defiled and will defile others if it is minimally the size of an olive. In contrast with tum’at okhlin, the Mishnah teaches that tum’at neveilah requires that the meat be the size of an olive, and cannot be supplemented with the animal’s skin or solidified meat juice or bones, sinews, horns or hooves.