Question (Rava): (A tradition obligates one who eats a Briyah (a creation), even if it is less than a k'Zayis.) If one ate an incomplete ant, what is the law?

Does the tradition apply only to a complete creation?

Or, does it apply to an amount that could live?

Answer (Rav Yehudah of Diskarta - Beraisa) Suggestion: "(One who touches) ba'Hem (becomes Tamei)" - perhaps only a complete Sheretz (rodent) is Metamei!

Rejection: "(If will fall) from them (into a oven, everything inside becomes Tamei)."

Suggestion: Perhaps even part of one is Metamei!

Rejection: It says "ba'Hem"!

Resolution: One is Tamei if he touches an amount equal to a full Sheretz. Chachamim estimated that this is the size of a lentil, which is the size of a Chomet (snail or lizard) when it is created.

Summation of answer: We require a full creation. (Surely, a Chomet could live even if a small amount was cut off. Nevertheless, we require the Shi'ur of a full Chomet!)

Rejection (Rav Shemayah): Less than the size of a lentil is not important for Tum'ah, for a soul never enters a Sheretz of this size. Something that was alive is important, even if it is missing something not vital to life! (Tosfos; Rashi - this applies only to Sheratzim, for a soul does not enter a Sheretz smaller than a lentil. A soul enters an ant smaller than a lentil, so the question remains.)

(Mishnah): The spine and skull (have Tum'as Ohel).

Question: Does this mean that together they are Metamei (b'Ohel), or each is by itself?

Answer #1 (Rava - Beraisa): If most of the ribs (the Rambam's text reads 'vertebrae') of the spine were broken, it is Tahor. If it is in a casket, even if they were broken or detached, it is Tamei, because the casket (joins them).

Inference: A whole spine is Tamei by itself.

Rejection: No. The Beraisa says that if most of the ribs are broken, the spine lost its Tum'ah. Perhaps the spine is Tamei only when it is with the skull!

Answer #2 (Beraisa - R. Yehudah): There were six things that R. Akiva was Metamei, and Chachamim argued, and R. Akiva retracted;

A case occurred in which a box of bones was brought into the synagogue of Tarsiyim (coppersmiths, weavers, or people from Tarsus). Tudus and other doctors said that there was not a (full) spine from one person.

Inference: If there were a spine or skull of one person, a Nazir would shave due to it!

Rejection: No, the doctors said that the bones were not even close to having Tum'as Ohel;

Not only was there not a spine and skull of one person, there was not even a spine or skull of one person!

Answer #3 (Beraisa): There are six things that R. Akiva was Metamei and Chachamim were Metaher. (Note: the previous Beraisa (Tosefta Ohalos 4:2) does not list the six things. Rashi and the Rosh explicitly say that we cite a Beraisa that lists them.) They are:

A limb from two Mesim;

A limb from two living people;

A half Kav of bones from two Mesim;

A Revi'is of blood from two Mesim;

A bone k'Se'orah that was divided into two pieces;

A spine and skull from two Mesim.

Inference: They are Metamei only together. If a spine or skull were Tamei by itself, R. Akiva would be Metamei seven things!

Rejection #1: The Beraisa lists only things about which the majority argued with R. Akiva. This excludes a bone k'Se'orah, for only an individual disagrees with this:

(Mishnah - R. Akiva): If a bone k'Se'orah was divided into two pieces, it is Tamei,

R. Yochanan ben Nuri is Metaher.

Rejection #2: The Beraisa lists only things from a Mes, not (a limb) from a Chai. (Rashi - the correct text of the Beraisa omits this; Rosh - both are counted like one.)

Rejection #3: The Beraisa lists only things for which a Nazir shaves due to their Tum'as Ohel. It omits a bone k'Se'orah.

Rejection #4: The Beraisa lists only things about which R. Akiva later retracted. It omits a Revi'is of blood, for R. Akiva never retracted about this.

(Rebbi): Do not list a Revi'is of blood among the matters about which R. Akiva retracted, for his source was not refuted;

Further, the verse supports him - "On the souls of any Mes he will not come."

(Beraisa - R. Shimon): In his life, R. Akiva never retracted. I do not know whether or not he retracted after he died.

For speaking about his Rebbi in this (jesting) manner, R. Shimon fasted so often that his teeth turned black.

Answer #4 (Beraisa): Beis Shamai say that a quarter Kav taken from two or three bones (has Tum'as Ohel);

Beis Hillel say, a quarter Kav from bones comprising the majority of the stature or number of bones has (Tum'as Ohel).

(R. Yehoshua): We can reconcile the opinions of Beis Hillel and Beis Shamai:

Beis Shamai discuss two or three bones, i.e. are two shins (they count only like one, since they are thin) and one thigh, or two thighs and one shin. These comprise the majority of the stature,

Beis Hillel include a quarter Kav from bones comprising the majority of the number of bones, e.g. the (120) bones in the fingers and toes (and five more, e.g. from the ankle. Beis Shamai agree, just they did not mention this.)

Shamai says, even from one bone of the spine or skull (has Tum'as Ohel).

Inference: Each is Metamei by itself!

Rejection: We cannot bring a proof from Shamai, for he is more stringent.

Inference: Only Shamai, who is stringent, says that either imparts Tum'ah by itself!

Rejection: Perhaps Chachamim argue only about one bone from the spine or skull, but they agree that if either is intact, it is Metamei.

Question (Rami bar Chama): Does Tum'as Ohel of a quarter Kav of bones from the spine or skull obligate a Nazir to shave?

The Mishnah said that he shaves for half a Kav. Perhaps this applies only to other bones, which are less stringent!

Or, perhaps the same amount applies to bones of the spine or skull.

Answer #1 (Rava - Mishnah): (He shaves for) the spine and skull.

If they were more stringent, the Mishnah should have said that a quarter Kav suffices! (The Mishnah connotes that they are intact. We are assuming that every spine and skull exceeds a quarter Kav.)

Objection: But Rava himself said (to explain a Mishnah) 'this teaches about a spine or skull less than the volume of a quarter Kav'!

Answer: Rava said that after hearing R. Akiva's opinion (before this, he assumed that every spine and skull exceeds a quarter Kav).