One who buys from a palter must tithe [separately] from each form; these are the words of R’ Meir. R’ Yehudah says: [He may tithe] from one for the whole. [But] R’ Yehu-dah concedes that if one buys from a monpol, he must tithe [separately] from each and every one.

One who buys from a baker may tithe from hot [bread] for cold [bread], and from cold [bread] for hot, even from many forms; these are the words of R’ Meir. R’ Yehudah for-bids, for I say: The wheat of yesterday was from one [person], and that of today was from another. R’ Shimon forbids with [respect to] terumas maaser, and permits with [respect to] challah.