Explanation #1: Rashi explains that the field in which the grave was found, and which has a field on either side, if it is the way of that particular valley to plow their fields from east to west ...

Explanation #1 (cont.): then one declares the field on its east and the field on its west a Beis ha'Peras ...

Explanation #1 (cont.): Whereas if they tend to plow it from north to south one declares the Beis ha'Peras the field to its north and the field to its south.

Introduction to Refutation: But what Rashi explains according to Rebbi Eliezer - that all four fields that surround the Beis ha'Peras a Beis ha'Peras, and that its earth is Metamei - is not correct ...

Refutation: Why is that? If they plow from east to west, why should they declare Tamei the fields on the east and on the west?

Explanation #2 (Rebbi Eliezer): It therefore seems that when Rebbi Eliezer says 'A Beis ha'Peras makes a Beis ha'Peras', he means whatever one plows up from a Beis ha'Peras into an adjoining field makes it a Beis ha'Peras ...

Explanation #2 (Rebbi Eliezer [cont.]): And that extends to where one plowed from the second field into a third one, and from the third into a fourth one - they all render the other field a Beis ha'Peras.

Explanation #2 (Chachamim): Whereas according to the Rabbanan, a Beis ha'Peras can only make the two adjoining fields a Beis ha'Peras

Explanation #2 (Chachamim [cont.]): And even then, each of them only become a Beis ha'Peras up to a hundred Amos.

Clarification: Rashi also explains that it is speaking about a field in which a grave got lost and from which one plowed into the adjoining field - which is why it makes a Beis ha'Peras of a hunmdrefd Amos beyond its borders, since the entire field is a Safek ...

Clarification (cont.): But a field in which a known grave has been plowed does not make a Beis ha'Peras.

Reason: Seeing as both of them own part of it.

Implied Question: And when we preclude Shutfin from "Atem" ...

Answer: That speaks with regard to the entire T'rumah not being valid, but part of the T'rumah of one of them and part of the T'rumah of the other, is T'rumah.

Explanation #1: Rashi explains that this refers even to the first one ...

Reason: Because, since the second one subsequently declared T'rumah, he indicates that he does not agree with the first one's T'rumah, rendering it a case of 'Giving T'rumah without the owner's consent'; and the same applies to the T'rumah of the second one.

Refutation: This is not correct however, since it is thrn not comparable to 've'Lo Temurah achar Temurah' - where the firs one is Temurah, but not the second one'.

Explanation #2: Consequently, the same explanation applies here - that the first one is Terumah and not the second one.

Introduction to Question: In the third Perek of Maseches T'rumos we learned 'Shutfin who took T'rumah; Rebbi Akiva says that the T'rumah of both of them is valid; whereas according to the Chachamim, if the first one took the correct amount ... ' ...

Question: Creating a contradiction in Rebbi Akiva's rulings?

Answer: It therefore seems that Rebbi Akiva here is speaking where they gave each other permission to take T'rumah, which is why the first one's T'rumah is effective - seeing as he took T'rumah with the consent of his friend ...

Answer (cont.): And that of the second one is not - since having given his consent, the first one's has already taken effect.

Answer (cont.): Whilst Rebbi Eliezer holds that the T'rumah of both of them takes effect - seeing as each one indicated that he gives his consent to the T'rumah of his friend ...

Answer (concl.): Whereas there it speaks where they did not give each other permission to take T'rumah. Consequently, each one took T'rumah off his own bat from his portion, and the T'rumah of each one takes effect partially.

Implied Question #1: Because Rebbi holds that for a Korban Yachid or to preclude a Tzibut and Shutfin it is not needed ...

Answer: Seeing as the entire Parshah of Temurah is written in the singular.

Implied Question #2: Nor do we need to preclude Kodshei Bedek ha'Bayis ...

Answer: Since they are not called a Korban ...

Implied Question #3: Or an Olah brought from left-overs ...

Answer #1: Since he holds that one brings Olas Mosros as a Nidvas Tzibur, and it is obvious that they cannot make a Temurah (Rashi).

Answer #2: One can also answer that Olas Mosros are brought as a Nidvas Yachid, and he holds like Rebbi Eliezer - that they do make a Temurah (See Rashak).

Clarification: The Gemara thinks that they do not make a Temurah at all ...

Reason #1: Because it went out to teach us something new, as the Gemara explains.

Reason #2: Or to teach us regarding Temuras Gufo - that it takes effect on something that is not eligible (Both explanations are given by Rashi).

Clarification: This means that if he called the tenth, the ninth, the ninth, the tenth and the eleventh, the tenth ...

Clarification (cont.): Since we Pasken in Bechoros (Daf 60a) that all three are sanctified.