Explanation (Rashi): According to R. Meir, who says that one who miscarried a Chayah or bird is Teme'ah Leidah, there is the stringency of two children [of different genders];

If the Chayah or bird is male, we impose on her the stringency of the Shilya. We are unsure whether it was a female regarding Tum'ah (she is Teme'ah for two weeks, like Yoledes Nekevah);

And we impose on her the stringency of Chayah or bird regarding Taharah. Perhaps there is no fetus in the Shilya (and Yemei Tohar end after 40 days).

Question (Maharam): If the Chayah or bird is a male, why are we unsure lest the Shilya was a female? This is a Sefek-Sefeka. Perhaps there is no fetus in the Shilya. And even if there is a fetus in the Shilya, perhaps it is a male!

Explanation #2: Rather, the stringency of two children applies to one who miscarried a Shilya on the second [day], after the Chayah or bird;

According to Rabanan, who say that one who miscarried a Chayah or bird has no Tum'as Leidah, she has no Yemei Tohar at all, for perhaps there is no fetus in the Shilya. Due to the Shilya, we put on her the stringencies of Yoledes Zachar u'Nekevah. And even if there is a fetus in the Shilya, perhaps it is a male!

Question: According to Rabanan, we should say that she observes only seven days for Tum'as Leidah [due to a Sefek-Sefeka]! Perhaps there is no fetus in the Shilya, and even if there is, perhaps it is a male!

Answer: If so, if she will see [blood] on day 34, and see again on day 41, we can also say (that she need not guard seven days of Nidah, due to Sefek-Sefeka):

Perhaps she did not give birth at all (so day 34 began Nidah, and she is only Shomeres Yom k'Neged Yom due to the blood on day 41). And even if there was a child, perhaps it was a female, and both sightings were Dam Tohar;

We cannot be lenient about both of these, for they contradict each other! (If she observes only seven days of Tum'as Leidah because perhaps the fetus in the Shilya was a male, we cannot say that since perhaps it was a female, she can be lenient when she sees on days 34 and 41.) Therefore, we are stringent about both of these.

Support: We must say so say in our Mishnah of one who miscarried, and does not know whether or not there was a child. She observes [the stringencies of Yoledes] Zachar and Nekevah, and Nidah, even though there is a Sefek-Sefeka:

Perhaps she did not give birth. And even if she gave birth, perhaps it was a male. Why must she observe two weeks [of Tum'as Yoledes, lest she gave birth, and it was a female]? Rather, surely it is like I said.

Question: We should say that its form was completed, and it delayed coming out until the eighth [month]! Rabah Tosfsah holds like this in Yevamos (80b);

He did so in practice, regarding a woman whose husband went overseas, and she gave birth 12 months later. He was Machshir the child (we assume that the child delayed an extra three months).

Answer: Most Amora'im argue with Rabah Tosfsah.

Explanation: Because the Mishnah mentions only R. Shimon, we ask what is his reason.

Explanation #1 (Rashi): [We ask that] granted, it dissolved. In any case, the entire body of the Mes is here. This should be like Rekev (corrosion) of a Mes, and Netzel (fluid that exudes from a Mes), which are Metamei).

Question: If so, what was the answer "any Tum'ah in which another species became mixed is Batel?"

How did we want to say that the child is Batel, because Dam Leidah is Mevatel Mashehu (a small amount) of the child, like [earth that fell in] a spoonful of Rekev, which we bring?

There, surely the Shi'ur is exact. When any amount [of the Rekev] is Batel [in the earth], there is less than a Shi'ur of a spoon (a double handful; some say, one handful);

However, when a little of the child is Batel, there is still more than a k'Zayis, or a spoonful!

Explanation #2 (Ri): The Nefel in the Shilya does not have the law of Netzel or Rekev, since it was not finished. It is not flesh, so that a k'Zayis would be Metamei. Rather, it is Metamei because it is a complete Mes;

We ask "what is R. Shimon's reason? There is an entire Mes here!", and answer that any Tum'ah in which became mixed...

This is the reason -- because Mashehu of it is Batel, it is Tahor.

Support #1: Now, we properly bring [that R. Shimon holds like he taught regarding] a spoonful of Rekev.

Explanation #2 (cont.): [The Gemara] asks "just the contrary!..." Also here, the Shefir is Mevatel Mashehu of the other species!

R. Yochanan answers that it is due to Bitul in the majority. Dam Leidah and fluid are the majority over the entire Shefir, and it is totally Batel, even in the first house;

Reish Lakish holds that even without Bitul in the majority, it is Tahor due to disorder of its form. It is torn in its waters and its form is disordered according to R. Shimon, even in the first house.

Support #2: Also from Reish Lakish we can prove that it is not Tamei due to Rekev or Netzel, for if so, we would not be Metaher due to disorder!

Rather, surely it is Tamei due to a complete Mes. Reish Lakish requires that also its form is intact.

The other Amora'im argue with him about disorder of the form, but they require that it is whole.

Question: According to the Hava Amina that R. Shimon is Metaher even in the inner house due to Bitul of Mashehu, why did the Beraisa say "just like it is not in the outer house, it is not in the inner house" due to Bitul of Mashehu?

Also according to R. Shimon, it is not totally Batel in the inner house like it is in the outer house. Rather, he is Metaher due to Bitul of Mashehu!

Answer: It means as follows. Just like you agree in the outer house, for it is dissolved, we should be Metaher in the inner house, due to Bitul of Mashehu, for there is not a complete Mes.

Question: In Nazir (50a), we ask "[why does the Mishnah teach that] a Nazir must shave [and begin Nezirus again from the beginning] due to [Tum'ah of] a Mes, or a k'Zayis of a Mes? If he must shave for a k'Zayis of a Mes, all the more so he must shave for a [full] Mes!"

We answer this is needed only for a Mes (i.e. Nefel) that does not have a k'Zayis of flesh, and its limbs are not tied with sinews [so it is not Tamei due to Ever Min ha'Mes].

Why didn't we say that it teaches about a Shilya? It is Metamei only if it is complete!

Answer #1: A Shilya is not called a Mes.

Answer #2: This is what the Gemara answered there (a Mes, i.e. Shilya without a k'Zayis of flesh...)

Explanation (Aruch): This is something that goes along with it.

Explanation: He is lacking blood [due to the murder].

Implied question: Ula taught in Nazir (51a) that there is Rekev of a Mes only if it came from the flesh, sinews and bones;

Inference: Rekev is Tamei only if it came from all three of them together. However, Rekev need not come from blood!

Answer: Even so, if some of the blood was lacking at the time of burial, the law of Rekev does not apply.

Explanation #1 (Rashi): E.g. he was buried in his garment.

Rebuttal (Rashbam): All agree that at the beginning, something else [that decays] is Galgilon (inhibits the law of Rekev)!

Explanation #2 (Rashbam): Here we discuss one who was buried naked. The practice was to plaster burial cavities with plaster, and once [the Mes] decayed, a spoonful of it was Tamei;

Afterwards, some of the plaster fell and mixed with the Rekev, which was already Tamei.

Implied question: Why didn't we make a Tzerichusa (show why each needed to be taught)?

Answer: (Clearly, we needed this.) It teaches that it is impossible that there is not a spoonful of Rekev before the earth (plaster) became mixed with it.

Implied question: A Mishnah in Chulin (77a) says that if a Mevakeres (an animal that did not gave birth yet) miscarried a Shilya, we cast it to dogs. (Why don't we bury it, to publicize that the mother is exempt from Bechorah, like here?)

Answer: There, we do not need publicity. All know that there is a fetus in a Shilya.

Question: In Bechoros (23a), regarding a Neveilah that is Batel in slaughtered animals, it says that it is not Metamei through touching, but it has Tum'as Masa (for one who moves it). It is as if the Tum'ah is there;

The Gemara asks from a cake of blood, which is not Metamei through touching or Masa, due to Bitul b'Rov. This shows that it is as if the Tum'ah is not there!

The Gemara answers that it is a rotten Tum'ah. We ask that this is fine according to Bar Pada, who expounds "Ad l'Ger" (a Neveilah is Metamei as long as a Ger Toshav, i.e. a Nochri who observes his seven Mitzvos, would eat it). However, according to R. Yochanan, who expounds "Ad l'Kelev" (as long as a dog would eat it), this is difficult!

Summation of question: Why don't we ask from [our Mishnah; Chachamim are Metamei because the Shilya contained] a Shefir? [R. Shimon holds that] it is not Metamei b'Ohel, due to Bitul b'Rov. This shows that it is as if the Tum'ah is not there!

We would not be able to answer that it is a rotten Tum'ah, for even a rotten Mes is Metamei!

Answer #1: The reason is due to disorder of the form, like Reish Lakish taught, and not due to Bitul b'Rov.

Answer #2: Since the reason for a Shefir is due to a full Mes (like Tosfos said above, 27a DH Mai), even though it is as if the Tum'ah is there, we cannot consider it whole, since it was totally Batel in the majority.

Question: What was R. Yochanan's question? It says below (28a) that R. Yochanan holds like R. Eliezer. It is better for Reish Lakish. He holds like Rabanan, for it says in Maseches Ohalos that Chachamim are Metaher!

Answer #1: R. Yochanan and Reish Lakish argue according to Rabanan. Reish Lakish holds that Rabanan are Metaher a Rova (quarter Kav of human ashes), and likewise they are Metaher even a whole [Mes] if the Sheled (spine and ribs; Rambam - skeleton) is not intact and the form was disordered;

However, if the Sheled is intact it is Tamei due to R. Yitzchak's teaching, which is like Rabanan;

It is not like R. Eliezer, for he holds that even if the Sheled is not intact it is Tamei, for R. Eliezer is Metamei a Rova of ashes!

R. Yochanan asked [Reish Lakish] what is his source that Rabanan are Metaher due to disorder of the form? Perhaps Rabanan's reason is because when it is burned, it is no longer called a Mes, even if it is whole and the Sheled is still there!

However, a Shefir is called a Mes and it is Metamei, if not due to Bitul b'Rov.

R. Yitzchak's teaching is not like Rabanan, rather, like R. Eliezer, who is Metamei a burned, incomplete Mes.

Implied question: Why does it mention that the Sheled is intact?

Answer: This is [needed to] be Metaher small openings.

Answer #2: R. Yochanan holds that Rabanan are Metaher only a Rova that is deficient. If the ashes are intact, even if the Sheled is not intact, it is Tamei.

Support: Now we need not distinguish between a Shefir or Shilya and a burned Mes in which the Sheled is not intact. Both are the same, according to Reish Lakish and R. Yochanan.

Citation (Yerushalmi): If the form of a Shefir was disordered, what is the law? R. Yochanan says that it is Tamei, and Reish Lakish says that it is Tahor.

Reish Lakish challenged R. Yochanan from R. Yitzchak Magdela'ah, and [R. Yochanan] answered that mid'Oraisa, even if the Sheled is intact, it is Tahor. Why did they say that it is Tamei? [It was] due to his honor.

Explanation: [It was] due to the honor of the Mes, that it not be [considered] Batel.

Observation: This is like Answer #1, that even when the Sheled is intact, it is Tahor mid'Oraisa;

[However,] it argues with the Bavli, which establishes R. Yitzchak's teaching like R. Eliezer. There (the Yerushalmi) establishes it like Rabanan.