(Mishnah): If there are two Kavim (two doughs, each one Kav), and there is a [dough of] a Kav of rice or a Kav of Terumah in the middle, they do not join;

Something that its Chalah was taken, if it is in the middle, they join, for it was already obligated in Chalah.

If a Kav of Chadash and a Kav of Yashan were Noshech each other - R. Yishmael says, he takes from the middle. Chachamim forbid.

If one takes Chalah from a Kav, R. Akiva says, it is Chalah. Chachamim say, it is not Chalah.

If there are two Kavim, that Chalah was taken from each by itself, and he returned and made them one dough - R. Akiva exempts (because the first separation was valid), and Chachamim obligate. It turns out that [R. Akiva's] stringency [causes] his leniency.

(Gemara) Question: [Our Mishnah] should teach rice (if it is in the middle, they do not join), and [it need] not teach Terumah!

Answer: Had it taught rice, and not Terumah, we would say that rice, since it is not from their species, it does not join (with doughs on both sides of it). Terumah, since it is from their species, it joins. Therefore, it needed to teach Terumah.

Or, had it taught Terumah, and not rice, we would say that Terumah, since it is not Nigrar (drawn after Chulin, to join to a Shi'ur), it does not join. Rice, since it is Nigrar (with wheat), it joins! Therefore, it needed to teach rice, and it needed to teach Terumah.

A Kav of rice does not make (doughs on both sides of it) join. A Kav of Meduma does not make join. A Kav of Terumah does not make join. A Nochri's Kav does not make join.

A Kav of another species makes join. A Kav of another woman makes join. A Kav of Chadash makes join. A Kav of something whose Chalah was taken makes join.

Question (R. Bun bar Chiyah): Does a Kav of Chalah make join?

Answer (R. Chalafta ben Sha'ul): A Kav of Hekdesh makes join. Kav of Chalah does not make join.

Question: What is the difference between [a Kav of] Hekdesh and [a Kav of] Chalah?

Answer: Hekdesh, it is proper to redeem it and obligate it. Chalah, it is not proper to redeem it and obligate it. (SHA'AREI TORAS ERETZ YISRAEL - it was kneaded before it was Hukdash. If the Gizbar kneaded it, it is exempt even after Pidyon!)