Rejection (Abaye): Granted, Tum'ah revives Tum'ah, but Taharah (water added to brine) does not revive Tum'ah!

Question (Abaye - Mishnah): If Kosher Efer (ashes) of the Parah Adumah was mixed with (regular) ashes, we follow the majority:

If the majority is Efer Parah, it (Rashi; Rambam - water Mekudash with the mixture) is Metamei one who (needlessly) touches or moves it. If the majority is (regular) ashes, it is not Metamei.

Summation of question: If we say that Tum'ah remains (even when it is the minority, and can be revived again), granted, it is not Metamei b'Maga (we consider that he touched ashes, for they are the majority), but it should be Metamei b'Masa (for he moves everything)!

Answer (Rav Dimi): Indeed, R. Yosi b'Rebbi Chanina taught that it is not Metamei b'Maga, but it is Metamei b'Masa!

Question (Abaye): Rav Chisda taught that a Nevelah is Batel in slaughtered meat, for it cannot become like slaughtered meat. (This is according to our text. Rashi - this is incorrect, for a Nevelah becomes Tahor when it putrefies! Rather, the text says "for slaughtered meat cannot become like a Nevelah");

Granted, it is not Metamei b'Maga, but it should be Metamei b'Masa!

Answer (Rav Dimi): We learned (a different version of) this law in the name of R. Chiya (and R. Yosi b'Rebbi Chanina answered your question):

(Beraisa - R. Chiya): Nevelos and slaughtered meat can be Mevatel each other.

(R. Yosi b'Rebbi Chanina): When Nevelah is Batel, it is not Metamei b'Maga, but it is Metamei b'Masa.

Question (Abaye - Mishnah - R. Eliezer ben Yakov): If a clump of blood came out of a large animal's womb, it must be buried. The animal is exempt from Bechorah;

(Beraisa - R. Chiya): The clump does not have Tum'as Maga or Masa.

Granted, it is not Metamei b'Maga, but it should be Metamei b'Masa!

Rav Dimi could not answer.

Answer: Perhaps this is different, for the Tum'ah spoiled. (Shitah Mekubetzes - Abaye suggested this answer; R. Gershom - the Gemara suggested it.)

Question: This answer is like Bar Pada, who says that Nevelah has severe Tum'ah (Tosfos - Av ha'Tum'ah; Rashi - Tum'as Masa) only if a Ger (Toshav) would eat it. It has light Tum'ah (Tosfos - Tum'as Ochlim; Rashi - Tum'as Maga) as long as a dog would eat it;

The clump is not Metamei because a Ger would not eat it.

How can we answer for R. Yochanan, who holds that it retains severe Tum'ah as long as it is fit for a dog? A dog would eat it!

This is left difficult.

(Bar Pada): Nevelah has severe Tum'ah if a Ger would eat it. It has light Tum'ah as long as a dog would eat it;

(R. Yochanan): It retains severe Tum'ah as long as it is fit for a dog.

Question: What is Bar Pada's reason?

Answer (Beraisa): "Lo Sochlu Chol Nevelah la'Ger (... Titnenah va'Achalah)" - it is called (and forbidden like) Nevelah only if a Ger (Toshav) would eat it.

R. Yochanan does not learn from here. He says that this excludes only a Nevelah that was spoiled from the beginning (before the animal died).

Bar Pada does not need a verse to exclude that case. It is like earth.

(Mishnah - R. Eliezer ben Yakov): If a cake of blood came out of a large animal's womb, it must be buried. The animal is exempt from Bechorah;

(Beraisa - R. Chiya): The cake does not have Tum'as Maga or Masa.

(R. Yochanan): The fetus is Batel in a majority of blood.

Question: Why does R. Yochanan require a majority? The cake was never fit to eat!

Answer: It was fit to eat before it came out. (It could have been eaten with the mother.)

(Mishnah - R. Eliezer ben Yakov): If any amount of water falls into Tahor brine (it was bought from an Am ha'Aretz, and Hashakah was done), it becomes Tamei.

Inference (Rav Nachman): This shows that we suspect an Am ha'Aretz of selling brine that is half (added) water (so with the addition, the majority is water).

Question: It shows only that he might sell brine that is almost half water! (Even if with the addition, half is water, it is Tamei!)

Answer #1: Indeed, this is what Rav Nachman means.

Answer #2: Tum'as Am ha'Aretz is mid'Rabanan, and Tum'ah of liquids is mid'Rabanan. Therefore, Chachamim are stringent only if the majority is water, but not if only half is water. (If the concern was only lest the brine is almost half water, we would not be stringent if a drop of water fell in, for surely this did not make the majority water.)

(Mishnah - R. Shimon ben Gamliel): If one buys a nursing animal from a Nochri, we are not concerned lest the (suckling) calf was born to a different animal (and the nursing animal has not yet given birth.)

If one sees nursing mothers in his herd, and some were Mevakros (this was their first birth), and others had previous children, (the calves nursing from the Mevakros are the Bechoros, and) he need not be concerned that a mother is nursing a different animal's child.

(Gemara - Rav): The Halachah follows the Mishnah everywhere in our Perek where there is no argument.

Question (Rav Sheshes): This is a poor teaching. Which Mishnah does it teach about?

It does not teach about the first Mishnah. R. Yishmael and R. Akiva argue;

It does not teach about the second Mishnah. (Everyone already knows that) R. Eliezer ben Yakov taught a small number of laws, and the Halachah always follows him! (Some say that the Halachah follows him in 102 places, the Gematri'a of "Kav" -- Chavos Ya'ir 94.)

Answer #1: It teaches that the Halachah follows R. Shimon in our Mishnah.

Rejection: There is an argument about his law, in a Beraisa (24a)!

Answer #2: It teaches that the Halachah follows R. Yosi ben ha'Meshulam (24b).

Objection: Rav explicitly taught this!

Answer #3: It teaches about hair of a Ba'al Mum (25a).

Rejection: Akavya ben Mahalal'el and Chachamim argue about this!

Defense of Answer #1: Really, it teaches that the Halachah follows R. Shimon. An argument in a Beraisa is not considered an argument. (Rashi - this is a general rule (presumably, because the Halachah follows the Mishnah). Sefas Emes - Rav discounts the argument only in this Beraisa, for it is erroneous.)