All peels contract tumah and convey tumah, and combine. R’ Yehudah says: [There are] three peels on an onion. The innermost [peel], whether [it is] whole or perforated, combines. The middle [peel], [if it is] whole, it combines, but [if it is] perforated it does not combine. And the outermost [peel], in either case, is tahor.

[Regarding] one who cuts [a food] in order to cook [it], even though he did not complete the cut, it is not a connection. [But if he cut it] in order to preserve [it], or to overcook [it], or to place [it] on the table, [it is considered] a connection. [If] he began to separate [the sections], the food with which he began [to separate] is not [considered] a connection. [Regarding] walnuts that one braided together, [or] onions that he bunched together, these are a connection. [If] he began to take [them] apart in [the case of] walnuts, or to peel [them] in [the case of] onions, it is not a connection. [The shells of] walnuts and almonds are a connection, until one crushes [them].

[The shell of] a slightly roasted egg [is a connection] until one cuts [it]. But [the shell of] an overcooked [egg is a connection] until he crushes [it]. A bone that has marrow in it is a connection until one crushes it. [The peel of] a pomegranate that one separated is a connection until he beats on it with a stick. Similarly, the bastings of launderers, and a garment that is sewn with kilayim, is a connection, until he begins to undo [it].

The green leaves of greens combine. But white [leaves] do not combine. R’ Elazar the son of Zadok says: The white [leaves] combine in [the case of] kohlrabi, because they are food. And in [the case of] lettuce, for they protect the food.