(Beraisa): "One who touches a bone..." refers to a bone k'Se'orah.

"Or a corpse" teaches about a limb detached from a Chai without sufficient flesh.

"Or a Mes" teaches about a limb detached from a Mes.

(Reish Lakish): "Or a grave" teaches about a grave from before the Torah was given. (One might have thought that "Adam Ki Yamus" refers only to one who will die after Matan Torah.)

Question: What is the case of a limb from a Mes?

If it has a bone k'Se'orah, we learned this from "a bone"!

Answer #1: Rather, it has no bone k'Se'orah, yet the verse says that it is Metamei! (This supports Reish Lakish (53b), and refutes R. Yochanan!)

Answer #2 (R. Yochanan): Really, the limb has a bone k'Se'orah;

We know from "a bone" that it is Metamei one who touches. "Or a corpse" is Metamei one who moves it.

(Mishnah): They sprinkle on him on days three and seven... (he does not restart Nezirus Taharah until he becomes Tahor).

Question: Does 'until he becomes Tahor' mean until dark on the seventh day, like R. Eliezer?

Or, does it mean until he brings Korbanos on day eight, like Chachamim?

Answer: The coming Mishnah says 'he resumes Nezirus immediately.' This implies that our Mishnah means, until he brings Korbanos.

This is like Chachamim, who say that Nezirus Taharah begins on day eight.

(Mishnah): If a Nazir became Tamei through any of the following, he does not shave and bring Korbanos Nazir Tamei. He does not lose the days he counted. They sprinkle on him on days three and seven, and he immediately resumes counting:

Schachos or Pera'os (these will be explained);

A field in which a grave was lost or plowed;

Chutz la'Aretz;

A cover of a coffin (Tosfos - a monument) or its supporting stones;

A Revi'is of blood;

Tum'as Ohel of a quarter Kav of bones;

Kelim that touched a Mes;

The days of Sefirah (the seven days a Metzora counts between the two times he shaves) and the days of Muchlat (when he had a Siman of absolute Tum'ah).

A tradition from Sinai teaches that days of Zivah and a Metzora Musgar (waiting to see if he will become Muchlat) count towards Nezirus.

(Gemara): Schachos are (foliage of) trees hanging over the ground. Pera'os are rocks protruding from a wall.

(Mishnah): Chutz la'Aretz...

Question: Did Chachamim decree Tum'ah on (one who enters) the air of Chutz la'Aretz?

Or, did they decree on (one who towers above) the soil?

Answer (Mishnah): They sprinkle on him on days three and seven.

If the decree was for entering the air (it is a mere stringency, not due to Tum'as Ohel), there would be no reason to sprinkle!

Conclusion: They decreed about the soil.

Rejection: Really, they decreed on the air. Regarding the other Tum'os it says that they sprinkle on him on days three and seven.

Support: The Mishnah also lists Kelim that touched a Mes. We do not sprinkle for these!