(Beraisa): (If one added a Rova of Se'or to a dough, and he has Parnasah elsewhere to separate on it...) And if not, he brings four Reva'im and is Mashich.

Inference (R. Yonah citing R. Ze'ira): This teaches that a Rova of Se'or that became Tevel in its place, it is Tovel four Reva'im (joins to obligate them in Chalah) elsewhere.

Inference: Nashuch is [connected] mid'Oraisa. (If not, this is like separating from Patur on Chayav!)

(R. Imi): R. Yochanan and Reish Lakish argued about this. R. Yochanan said, Nashuch is mid'Oraisa. Reish Lakish said, Nashuch is not mid'Oraisa.

R. Chiya bar Ba switches the opinions (R. Yochanan holds that it is not mid'Oraisa, and Reish Lakish holds that it is mid'Oraisa.)

Question (to R. Yosi): What did you hear from R. Yochanan [about Nashuch]?

R. Yosi: I did not hear anything, but we can explain the words of Rabanan (R. Yochanan and Reish Lakish, here), from their words there;

(Mishnah): One who gathers Chalos with intent to separate them, and they were Noshech, Beis Shamai says, this is connection for a Tevul Yom (if he touched one, all became Tamei), and Beis Hillel say, it is not a connection... (and they agree about all other Tum'os, whether light or severe).

(Reish Lakish): From what we learned (Beis Hillel say,) it is not a connection [mid'Oraisa], this teaches that one is not liable for it for a Tahor eating Tamei. (It is only like a Shelishi l'Tum'ah, which is forbidden only mid'Rabanan - OHR SOMAYACH.)

(R. Yochanan): Tevul Yom is different, for he is called Tahor and Tamei ("v'Tamei Ad Ha'arev v'Taher'' - v'Taher applies even during the day). He is Tahor for Chulin [even] during the day, and for Terumah at night (but during the day, he is Tamei for Terumah).

Inference (R. Yochanan): Something that is not connected for a Tevul Yom, it is [connected] mid'Oraisa [for other Tum'os].

Conclusion: [R. Yochanan] says that Nashuch is mid'Oraisa. Reish Lakish, who said 'this is not mid'Oraisa', he holds that Nashuch is not mid'Oraisa.

Question (against Reish Lakish - Beraisa): And if not, he brings four Reva'im and is Mashich.

Answer #1 (R. Hoshayah): The case is, the Se'or [is obligated] only due to Nashuch. (Since the Chiyuv is mid'Rabanan, we can rely on Nashuch to separate the Chalah.)

Answer #2 (R. Ze'ira): What do R. Yochanan and Reish Lakish argue about? It is when it became Nashuch by itself, but if he was Mashich it with his hands, all agree that Nashuch is mid'Oraisa. (We explained this like GRA.)

Answer #3: Even if you will say that they argue [even] about one who was Mashich it with his hands, Reish Lakish holds like he taught elsewhere;

(Reish Lakish citing Chizkiyah): Tevel is Batel in a majority. (The Se'or is obligated mid'Rabanan, we can rely on Nashuch to separate the Chalah.)

(R. Yosi bei R. Nehurai): Tevel is Batel in a majority.

(R. Yochanan): Tevel is not Batel in a majority. (Since one can make it Terumah on another place, it is as if it one can separate it. Bitul applies only when one can separate the Isur.)