Text #1: This is the text in the Sefarim.

Text #2: In Rabeinu Tam's explanation and in the Mishnah in Tevul Yom (3:1) there is a different text. The text reads, "Rebbi Meir says that if he holds the larger part and the smaller part comes up with it, it is like (it is part of) the larger part. Rebbi Yehudah says that if he holds the smaller part and the bigger part comes up with it, it is like the bigger part."

Question: There is a difficulty with this text. How can our Gemara ask a contradiction in Rebbi Meir?

Implied Question: It is illogical to explain that Rebbi Yochanan who says that if he holds the smaller part and the bigger part does not come up with it according to Rebbi Meir etc. does not really mean this. Rather, he means that the small part also does not come up with the big part.

Answer: This explanation is not implied by Rebbi Yochanan.

Question: This is difficult. What is prompting Rabah's question? If it is because an animal when it is alive cannot become impure, it is no different than all Yados that do not become impure themselves, but rather act as conduits to bring and give impurity (from the item for which they are a Yad)!

Answer: An animal is unlike other Yados that cannot become impure because they are not food. An animal is sometimes unable to become impure even when it is food, such as a Ben Pekuah regarding which there is an opinion (75a) that it cannot become impure.

Implied Question: This is despite the fact that the Gemara in Gitin (22a) states that a tree that is rooted in Eretz Yisrael and whose branches spread into Chutz la'Aretz is considered in Eretz Yisrael. (How can we reconcile this with our Gemara?)

Answer: In that case (ibid.) the tree was mainly receiving nourishment from its roots. However, when the main part of the plant is in a pot, the nourishment of the roots is not a large amount of nourishment, and the branches do not get nourishment from the pot.

Implied Question: This is despite the fact that regarding a potted plant with a hole in the bottom we say in Shabbos (95b) that according to Rebbi Shimon it is considered attached to the ground regarding its seeds being able to become impure. The same would seem to apply regarding it becoming impure. (Why don't we say the same regarding our Gemara?)

Answer: In the Gemara (ibid.) there, the plant is considered connected to the ground due to the hole. However, in our case, the branches that are outside the pot do not make what is in the pot (without a hole) connected to the ground.

Opinion #1: According to the second explanation in Rashi that the question is whether the half that he did not bow down to is a Yad to make other things impure or not, meaning is food a Yad regarding other food, this is difficult.

Question #1 (cont.): In our entire Gemara it is apparent that food can become a Yad for other food. For example, when the Gemara later says that a kidney of a Neveilah is together with its fat, it says that the fat is made into a Yad for the kidney.

Question #1 (cont.): Earlier, they only argue regarding the animal being a Yad for a limb, since the animal is a bigger item (than the limb) and it is therefore not fitting that it should be a Yad. However, if the rest of the animal and the limb were the same size, everyone would agree it could be a Yad for the limb.

Question #2: Additionally, why does Rebbi Yirmiyah discuss a gourd? He should inquire regarding two pieces of meat that are stuck to skin, and one of them becomes impure due to contact with a Sheretz!

Answer: One should not say that the case is regarding a gourd that is connected to the ground, and half of it is impure due to it being an Asheirah. The question would be if the other half is a Yad to bring the impurity to other items since it is attached to the ground, similar to the question regarding the squash that was planted in a pot.

Question: Even so, he should not discuss a gourd. He should ask regarding someone who bows to half of a tree!

Opinion #2: It appears that the first explanation of Rashi is correct. This explanation is that the question is if a Sheretz touched the half to which he bowed. Does it become a Yad to the second half? The reason it would not is because it cannot become impure according to Rebbi Shimon who says that food that cannot be fed to others is not considered food.

Opinion #2 (cont.): This is unlike other cases of Yados, as they usually do not accept impurity because they are not fit to be considered food, and are considered like wood. However, here it is food, but something else causes it to be considered that one cannot feed it to others, as I have explained earlier regarding the question of an animal while it is alive etc.

Implied Question: The Gemara earlier (127b) said that figs that dried while connected to the ground can have impurity of food. (This seems unlike the position of Rebbi Yehudah!)

Answer #1: This is unlike Rebbi Yehudah.

Answer #2: Alternatively, dried it is not even like it is entwined with the (bark of the) tree.

Explanation: This is referring to a whole kidney and a whole upper lip. However, half a kidney or upper lip does not become impure even though it does not regenerate. This is because we derive from a dead animal to a limb that just as a dead animal is impure as it is significant, so too a limb (and not half a limb) is significant.

Implied Question: This is despite the fact that Rebbi Yosi ha'Glili does not derive from a whole animal.

Answer: He does derive from an animal regarding the limb needing to be somewhat significant.

Implied Question: One should not say that even a half of a kidney or upper lip is impure because they do not regenerate. (Why not?)

Answer: This is because bone does not regenerate, and if it breaks and falls off an animal while it is alive it seemingly would not be impure. The bone from a live animal should not be more impure than that of a Neveilah regarding which we derive, "with its carcass - and not its bones." While the bone of a dead person the size of a barley does cause impurity, less than that does not even though it does not regenerate.

Question: Our Gemara states that flesh regenerates besides for a kidney and lips. In Nidah (55a), the Gemara says that just as a new bone does not take the place of the old bone etc. The Gemara asks, isn't flesh etc. The Gemara answers that the area of the wound has a scab (meaning that the flesh does not regenerate completely).

Answer: Each comment is based on the Pasuk discussing that topic. In the Gemara in Nidah (ibid.), it is similar to the bone that heals slightly but not as it was originally. Flesh, similarly, has a scab. Our Gemara is saying that it is like death and does not regenerate at all. This is why our Gemara states, "Chalifin - an exchange," while the Gemara in Nidah (ibid.) discusses "a new root."

Text #1: Some Sefarim have the text, "Rechuvah - (ankle or knee) joint."

Proof: This appears to be correct, as this is why Rebbi Akiva does not require flesh as a condition, since the joint is a limb in the animal that does not have flesh on it. Rebbi, on the other hand, decided his position based on most limbs. He would not even say that the joint itself is impure.

Proof (cont.): However, if the difference between them would not be the joint, we would not know Rebbi Akiva's reasoning regarding why he does not derive from an animal that we should require flesh. This is not a question regarding the opinion of Rebbi Yosi ha'Glili, as he does not derive from an animal.

Text #2: The Riva (supports the text of "flesh" as opposed to "joint" and) explains that everyone agrees regarding a joint that because it was created without flesh it is no less (regarding impurity) than other limbs. They only argue regarding a limb that had flesh that was removed from the limb.