Question (Kahana, to Shmuel): Is it not reasonable that the Meduma taught in our Mishnah [that is exempt from Chalah] is when the majority is Terumah?

Answer (Shmuel): Also I hold like this. However, when you ascend to Eretz Yisrael, ask this!

When [Kahana] ascended to Eretz Yisrael, he heard R. Yosa say in the name of R. Yochanan 'even one Se'ah [of Terumah] that fell into 99 of Chulin.' (Even though mid'Oraisa, the Terumah is Batel, mid'Rabanan it is Meduma. It can exempt from Chalah nowadays, after the Churban, which is mid'Rabanan.)

Question (R. Avahu): Reish Lakish asked R. Yochanan, does one Se'ah exempt everything?! (Reish Lakish holds like Shmuel, that only a majority of Terumah exempts.)

Answer (R. Yochanan): When a ring [of Terumah figs fell] into rings [of Chulin figs, we remove one and give it to a Kohen, and the rest are permitted to Zarim]. Is it clear that the Terumah came to his hand (that we permit the rest), and you said that this is a leniency (because nowadays, Terumah is mid'Rabanan);

Also here, this is a leniency [of Chalah nowadays, which is mid'Rabanan! We explained this like MAHARA FULDA.]

(R. Yonah and R. Yosi, both citing R. Ze'ira): Even if [Terumah] wheat [became mixed with Chulin] wheat, he grinds [it all] and permits. (This shows that the Heter is due to Bitul, and not because we assume that the Terumah came to his hand - RIDVAZ.)

(Mishnah): And less than five Reva'im of grain [are exempt from Chalah].

Inference (R. Avuna): This teaches that less than five Reva'im [are exempt], but if they were exactly five Reva'im, no (they are not exempt).

(R. Yosi bei R. Bun citing R. Avuna): This was not said about this, rather, about R. Yochanan's teaching 'Meduma is exempt from Chalah. Safek Meduma, which is eaten in spite of Dimu'a (even Zarim are permitted), is obligated in Chalah;

About this, R. Yosi bei R. Bun citing R. Avuna said 'this was said when there are more than five Reva'im (and there are five Reva'im without the Terumah), but if they were exactly five Reva'im, it is exempt from Chalah. (We explained this like MAHARA FULDA, GRA.)