Answer: The second Beraisa refers to Chulin, which do not need intention when washing or immersing one's hands.

This is proved from a Mishnah (Machshirin 4:7) which says that if fruits fell into water and a person with Tamei hands reached in to get them without intention for his hands to become Tahor, they become Tahor anyway.

Question: But our Mishnah says that if one had Kavanah for Chulin while immersing, he may eat Chulin but not Ma'aser.

This implies that one must have Kavanah when immersing for Chulin!

Answer: The Mishnah is teaching that his Kavanah for Chulin does not help for Ma'aser (but he does not need Kavanah for Chulin).

Question: But our Mishnah says that if one immersed without Kavanah, it is as if he did not immerse!

This implies that his immersion is completely useless, even for Chulin!

Answer: No, it means that his immersion does not help for Ma'aser (but it does help for Chulin, even with no Kavanah).

A Beraisa collaborates this understanding of the Mishnah.

(R. Elazar): One who immersed and came out of the Mikvah may still be Machzik himself (i.e. have Kavanah) for whatever he wants (Chulin, Ma'aser, etc.).

Question: A Beraisa contradicts this!

(Beraisa): If one immersed with Kavanah for a lower level item (e.g. Chulin), he may change and have Kavanah for a higher level item (e.g. Ma'aser), as long as one leg is still in the Mikvah.

But if he is completely out of the Mikvah, he can no longer have Kavanah!

Answer: The Beraisa means that if he had Kavanah while he was in the Mikvah, he cannot have Kavanah for something else when he comes out (unless one leg is still in the Mikvah).

But if he did not have any Kavanah while in the Mikvah, he may have Kavanah for whatever he wants even after he comes out.

Who is the Tana of the Beraisa (that states that as long as one's leg is still in the Mikvah, he may have Kavanah for whatever he wants), who holds of "Gud Achis"?

(R. Pedas): It is R. Yehudah, as we see from the Mishnah (Mikva'os 7:6).

When two people immerse consecutively in a Mikvah that has exactly 40 Se'ah, the second person remains Tamei (since the first diminished the Shi'ur of the Mikvah when he emerged with water on him).

R. Yehudah says that if the first person's feet were still touching the water in the Mikvah, then the second person becomes Tahor (because of "Gud Achis").

Question: May small utensils (needles and weaving forks) be immersed by placing them on the head of the person standing in the Mikvah?

Does R. Yehudah only hold of "Gud Achis" but not "Gud Asik," or does he also hold of "Gud Asik?"

Answer: R. Yehudah said (in a Tosefta) that in the case of three Mikva'os on a hill -- the upper one and lower one each with 20 Se'ah, and the middle one with 40 Se'ah -- one may immerse only in the lower one and not in the upper one.

From here we learn that R. Yehudah holds only of "Gud Achis" and not "Gud Asik."

Question: Who is the Tana of our Mishnah?

The Mishnah says that one who immersed with intention for Chulin may not eat Ma'aser.

This implies that the Tana of the Mishnah holds that there is a difference between Chulin and Ma'aser.

Answer: It is the Rabanan, who differentiate between Chulin and Ma'aser.

Question: But the end of the Mishnah implies that there is no difference between Chulin and Ma'aser!

Answer #1: The beginning of the Mishnah is the Rabanan, and the end is R. Meir (who does not differentiate between Chulin and Ma'aser).

Answer #2 (R. Acha bar Ada): We must add another level (Ma'alah) to the end of the Mishnah, so that Chulin and Ma'aser are differentiated from each other.

As a result, the entire Mishnah is the Rabanan.