[There is] a stringency in chelev over blood, and [there is] a stringency in blood over chelev. The stringency in chelev is that one is guilty of me’ilah on its account, and one is liable on its account for piggul, leftover, and tumah, which is not the case with blood. The stringency of blood is that [the prohibition of] blood applies to domestic animals, beasts, and fowl, both nonkosher and kosher, whereas [the prohibition of] chelev applies only to kosher domestic animals.

The hide, the gravy, the spices, the shreds, the bones, the gidin, the horns, and the hooves combine to convey the tumah of foods but not the tumah of neveilos. Similarly, [if] one slaughters a nonkosher animal for a gentile and it [still] convulses, it conveys the tumah of foods but not the tumah of neveilos until it dies or until he chops off its head. [Scripture] has provided for more things that convey tumah of foods than that convey tumah of neveilos. R’ Yehudah says: Shreds that were gathered together, if there is the volume of an olive in one place, one is liable on its account.

The skins of the following are like their flesh: the skin of a man, the skin of the domestic pig — R’ Yose says: Also the skin of the wild pig — the skin of the hump of a tender camel, the skin of the head of a young calf, the skin of the hooves, the skin of the pudenda, the skin of a fetus, the skin under the fat-tail, and the skin of the hedgehog, the chameleon, the lizard, and the snail. R’ Yehudah says: The lizard is like the weasel. But any of them that was tanned, or trodden as long as required for tanning, is tahor, except for the skin of a man. R’ Yochanan ben Nuri says: The eight sheratzim have skins.

[If] one flays either an animal or a beast, either kosher or nonkosher, either small or large, for a spread — enough to grasp it; for a flask — until he flays the breast. [If] he flays it from the feet, it is all [considered] attached as regards tumah, both to contract tumah and to convey tumah. The skin on the neck — R’ Yochanan ben Nuri says: It is not [considered] attached, but the Sages say: It is [considered] attached until he flays it completely.