1) A DISINTEGRATED FETUS AS THE "BECHOR"
QUESTION: In the Mishnah, Rebbi Eliezer ben Yakov says that a large clump of blood that was discharged from the womb of an animal must be buried, because, as RASHI explains, it might have been composed of the fetus of a firstborn male which became Kadosh upon exiting the womb. The Gemara cites Rebbi Chiya who teaches that the clump of blood is not Metamei through Maga (touching) or Masa (carrying) it. If it is not Metamei, then it also should not have the status of a Bechor. Why, then, must it be buried, and why does it exempt the next animal that is born from the law of Bechor? Rebbi Yochanan explains that it indeed is considered Kadosh, and the reason why it is not Metamei is because the fetus that it contained became Batel b'Rov.
RASHI (DH Bitul) explains that the flesh of the disintegrated fetus comprises a minority of the mixture, with blood and other materials comprising a majority.
If the fetus in the clump of blood is only a minority of the ingredients of the mixture, then why is the next animal that is born not considered the Bechor? The first birth should not be considered a birth at all, but merely a discharge of blood, since whatever fetus was there was Batel! Therefore, the subsequent birth should be considered the first real birth, and the calf that is born should have the status of a Bechor.
ANSWERS:
(a) The KEHILOS YAKOV (#20) suggests that this case can be compared to a theoretical case in which the fetus of a firstborn was burned in the womb of the mother. What would be the Halachah in such a case? The Kehilos Yakov cites the Mishnah (19a) which discusses a case of a firstborn animal that was born through a Caesarian section ("Yotzei Dofen"). The Halachah in that case follows the view of Rebbi Akiva, who says that neither the first nor the second animal that is born is a Bechor, because only an animal has the status of a Bechor only when it is the Bechor in two respects (it was the first to emerge naturally from the womb, and it was the first male offspring of its mother). An animal that was the first male offspring but was not the first to emerge naturally, or an animal that was the first to emerge naturally but was not the first male, is not considered the Bechor.
The Kehilos Yakov suggests that if, in a case in which the fetus was burned while inside the womb, the second animal is a Bechor only in one respect because it is not the first fetus that the womb contained, then this would also explain the case of the Gemara here. Even though the disintegrated fetus was Batel to the blood and other material, nevertheless it was the first fetus in the womb, and thus the second animal that is born is a Bechor only in one respect.
(b) The Kehilos Yakov, however, rejects this approach, because it is logical that an animal is considered a Bechor in one respect only when it emerges from the womb first, but not when it merely occupied the womb (but did not emerge) first. When a fetus is destroyed in the womb, or when it emerges in a disintegrated form in a clump of blood, it is not considered to be the first for anything, and the animal that is born afterwards should be considered the Bechor in all respects! Proof for this can be adduced from a case in which an animal was pregnant with twins, and one twin ("A") completed its development before the other ("B"), but twin "B" was born first. In that case, it should be logical that neither animal is considered the Bechor; "A" is not the Bechor for birth, and "B" is not the Bechor for development. This certainly is not the Halachah, though, because it would mean that every time twins are born, there would be a doubt whether the first one that is born is the Bechor (perhaps it only emerged first, but did not develop in the womb first). Rather, the Halachah is that when two male twins are born, the first one to emerge is given to the Kohen as the Bechor. Accordingly, developing in the womb first is not a prerequisite to be considered the Bechor.
Therefore, the Kehilos Yakov offers a different answer to the question. It must be that when an object is Batel b'Rov, this means that the minority loses the Halachic status that it possessed previously and acquires the same status as the majority. However, its essence remains the same; its defining title is not Batel. The first baby, even though it disintegrated, is still called a "baby." Even though there is more blood and other material in the mixture, the disintegrated fetus is still considered a "baby" even though it does not possess the status, or laws, of a baby. Even according to the opinion that Tum'ah that becomes Batel is considered no longer extant and cannot be revived (this seems to be Abaye's opinion, as implied by his question at the end of 22a), this means only that the laws of the minority are lost, but nevertheless the object retains its defining title.
According to this approach, the clump of blood is called a "baby" and the mother is considered to be an animal that has already given birth once. Consequently, the next baby is exempt from Bechorah. (The Kehilos Yakov proceeds to question his answer from the words the MAHARIT ALGAZI #30, DH v'Hineh, in the name of the MORDECHAI, Chulin #737.) (D. BLOOM)
2) THE "TUM'AH" OF A CLUMP OF EARTH FROM CHUTZ LA'ARETZ
QUESTION: Rav Dimi quoted Rebbi Yochanan as saying that there are three different types of Pikah (with regard to three different Halachos) -- a Pikah Shel Shesi, a Pikah Shel Erev, and a Pikah Gedolah. Rav Dimi did not know to what Halachos these three sizes refer.
Ravin in the name of Rebbi Yochanan explained to what Halachos these three sizes refer. In order for the stillborn fetus of a woman to be Metamei b'Ohel even before it exits the womb entirely, the head must be the size of a Pikah Shel Shesi, a coil of wool of the warp. In order for the stillborn fetus of an animal to be Metamei as a Neveilah inside the womb, the head must be the size of a Pikah Shel Erev, a coil of wool of the woof. In order for a clump of earth from Chutz la'Aretz to be Metamei (mid'Rabanan), it must be at least the size of the Pikah of sack-makers.
RASHI (DH Gush) explains that such a clump of earth is Metamei b'Ohel.
How can Rashi say that the earth of Chutz la'Aretz is Metamei b'Ohel? The Mishnah in Ohalos (2:3) states clearly that earth from Chutz la'Aretz is not Metamei b'Ohel! (RASHASH)
ANSWERS:
(a) The MISHNEH L'MELECH (Hilchos Tum'as Meis 11:1) suggests that there is a printing error in the words of Rashi (and the word "b'Ohel" should be removed).
However, this answer is difficult, because Rashi in numerous other places repeats his view that the earth of Chutz la'Aretz is Metamei b'Ohel (see Rashi to Sanhedrin 12a, DH Chosheshin; Eruvin 30b, DH Eretz ha'Amim).
(b) Rashi's statement is consistent with the opinion that when the Mishnah in Ohalos says that Chutz la'Aretz is not Metamei b'Ohel, it means that it is not Metamei only when an awning or shelter covers both earth of Chutz la'Aretz and a person ("Tum'as Ohel b'Hamshachah"). However, it is Metamei b'Ohel when the person himself leans over earth from Chutz la'Aretz ("Ma'ahil"). This opinion is recorded by TOSFOS in Gitin (8b DH d'Gazru).
(c) Alternately, Rashi may understand that the Mishnah in Ohalos is referring to the time before the Rabanan instituted their decree (Shabbos 15b) that even the air of Chutz la'Aretz is Metamei (that is, one who passes through the air over Chutz la'Aretz becomes Tamei), as RABEINU TAM (cited by Tosfos to Gitin 8b, DH d'Gazru) explains. After the Rabanan made their decree, however, the earth of Chutz la'Aretz is effectively Metamei b'Ohel (one who enters the airspace and is "Ma'ahil" over the earth becomes Tamei).
However, Rashi in Gitin (8b, DH d'Gazru) seems to contradict what he says here. Rashi in Gitin writes that earth of Chutz la'Aretz is not Metamei b'Ohel, and he quotes the Mishnah in Ohalos as his source!
How are we to reconcile the contradictory remarks of Rashi?
The Gemara in Nazir (54b) asks whether the decree that Chutz la'Aretz is Tamei extends to the air of Chutz la'Aretz, or applies only to the earth. Tosfos in Gitin (8b, DH Ela) explains that there is no doubt that the air of Chutz la'Aretz is Metamei. The Gemara's question in Nazir is simply what causes this Tum'ah. Is the air of Chutz la'Aretz Tamei because it acts as an Ohel above the land of Chutz la'Aretz, and the land is Metamei b'Ohel, or is the Tum'ah of the air a separate type of Tum'ah altogether which does not stem from the Tum'ah of the land of Chutz la'Aretz. If the air is independently Tamei, then it is impossible for someone to enter Chutz la'Aretz (from Eretz Yisrael) and remain Tahor; the air will always make him Tamei. If, however, the air of Chutz la'Aretz is Tamei as a consequence of being an Ohel over the earth of Chutz la'Aretz, then one who enters Chutz la'Aretz while sitting on something that serves as a divider between him and the earth below remains Tahor. (See Insights to Nazir 55:1.)
The words of Rashi here and in Gitin might depend on the two sides of the question of the Gemara in Nazir. According to the first possibility, the earth of Chutz la'Aretz is clearly Metamei b'Ohel. According to the second possibility, the earth of Chutz la'Aretz is not Metamei b'Ohel, and therefore the Rabanan found it necessary to add a decree to be Metamei the air of Chutz la'Aretz.
3) HALACHAH: REVIVING SOMETHING THAT IS "BATEL"
OPINIONS: Reish Lakish says in the name of Rebbi Yehudah Nesi'ah that one who purchases Tzir (brine mixed with water) from an Am ha'Aretz may perform Hashakah with it and use it. If the majority of the brine is water, then the Hashakah is Metaher it, since Hashakah is Metaher water. If the majority is brine, then it is not Tamei in the first place, since brine is not considered food and is not Mekabel Tum'ah. The water that is mixed with the brine does not become Tamei because it is Batel to the brine.
Rebbi Yirmeyah says that this allowance to use the brine applies only to using it as a dip, when no additional water will be added to it. One may not use the brine for cooking, because when the additional water is added to it, it joins with the water already mixed with the brine and makes a majority of water. Since the water is no longer Batel, it is "revived" and its Tum'ah returns.
What is the Halachah with regard to reviving an Isur that was Batel?
(a) The RASHBA (Chulin 100a, cited by SHULCHAN ARUCH YD 109:2) rules that when a piece of dry Isur becomes mixed with two pieces of Heter, one may eat all three pieces. If, however, all three pieces were then cooked together, such that the taste of the Isur is now discernible in all three pieces, the mixture is prohibited (until the amount of Heter is sixty times more than the Isur). Even though the piece of Isur was Batel when it first became mixed with the Heter (when the pieces were dry, before they were cooked), it returns to its original status of Isur when it is cooked and is no longer Batel.
(b) The ROSH (Chulin 7:37) disagrees and rules that once an Isur is Batel, it can never return to its state of Isur. The ROSH explains that a piece of Isur that was Batel is not comparable to the case of the Gemara here, in which Tamei water that was Batel in the Tzir is "revived." Even though the water was Batel with regard to Tum'as Maga, it was never Batel with regard to Tum'as Masa (since it is possible to carry the entire mixture at once, as the Gemara discusses later, end of 23a). Consequently, when the water becomes the majority, it can return to the status of Tamei. In contrast, when Isur is Batel it loses all aspects of Isur and cannot be revived in any manner. (See also Insights to Avodah Zarah 73:3, Chulin 100:1.)

22b----------------------------------------22b

4) REMOVING A "SE'AH" FROM THE MIXTURE AND LETTING IT ROT
OPINIONS: Abaye (end of 22a) attempts to prove to Rav Dimi that Tum'ah that has become Batel cannot be revived. He quotes the Mishnah in Terumos (5:2) that discusses a case of one Se'ah of Terumah that is Tamei that falls into one hundred Se'ah of Chulin that is Tahor. Rebbi Eliezer maintains that one must remove one Se'ah from the mixture and leave it to rot, because we say that the one that fell in is the one that is removed.
Is the Se'ah that is removed treated like the actual Se'ah of Terumah Teme'ah, or is it left to rot merely symbolically?
(a) RASHI (DH Teirom) writes that the Se'ah is treated exactly like Terumah Teme'ah. This implies that one may burn the Se'ah and benefit from it while it is burning, just as one may do with any Terumah Teme'ah. When Rebbi Eliezer says that one should let it rot, he does not mean that it must rot as opposed to being burned.
This view is supported by the Yerushalmi (cited by Tosfos DH Teirom), which quotes Rebbi Eliezer as saying "let it burn" instead of "let it rot."
(b) However, RABEINU TAM (cited by Tosfos) explains that the Yerushalmi means that it may be burned only in a way similar to letting it rot -- that is, without benefiting from the Se'ah while it is burning. The Chachamim prohibited benefiting from the Se'ah even in a manner in which it is permitted to benefit from ordinary Terumah Teme'ah, lest a person mistakenly permit the Se'ah to be eaten (since the reason the Chachamim prohibited the eating of the Se'ah is not clear to all).
(c) Alternatively, Tosfos (ibid.) suggests that the Bavli and the Yerushalmi may be arguing with regard to whether one may benefit from the Se'ah while it is being burned. The Yerushalmi permits benefiting from it ("let it burn"), while the Bavli prohibits benefiting from it ("let it rot").

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