1) THE SIGNIFICANCE OF A "BIRYAH" FOR A "SHOMER"
QUESTION: Rav (118b) teaches that an outer shell is not considered a "Shomer" with regard to the laws of Tum'as Ochlin when it is protecting an object that is smaller than a bean. The Gemara questions Rav's ruling from a Beraisa in which Tana d'Vei Rebbi Yishmael states that the husk of a grain of wheat, barley, or a lentil is considered a Shomer, even though those items are smaller than the size of a bean. The Gemara answers that Rebbi Yishmael is referring to a Shomer for an object that is a Biryah (an item that is whole and complete like it was when it was created). Rav agrees that a Shomer for such a food is considered a Shomer even when the food is smaller than a bean.
Why should the fact that the food is a Biryah determine whether or not its outer protective shell is considered a Shomer?
(a) In general, the significance of a Biryah comes from the fact that a whole entity is a more important item than a piece of something the same size. This concept is expressed in Makos (17a) with regard to the Isur of eating bugs. One who eats an entire bug transgresses the Isur of eating bugs, regardless of the bug's size. In contrast, one who eats part of a bug is not liable unless he eats the amount of a k'Zayis. The Gemara there clearly states that this is because a Biryah (a whole bug) is considered significant. Rebbi Shimon in Makos extends this to a grain of wheat, stating that one who eats a grain of wheat from which Terumos and Ma'aseros have not been separated has fully transgressed the prohibition of Tevel, even though he has eaten less than a k'Zayis.
However, this does not seem to be the opinion of RASHI here (119b, DH Chitim). The Gemara discusses the question of whether two Shomrim can combine with the food to make a k'Beitzah. Rashi explains that the Gemara seeks to prove from Tana d'Vei Rebbi Yishmael that the "husks" (in the plural) of a grain of wheat or barley become part of the grain so that it can be Mekabel Tum'ah. This implies that two Shomrim do combine to make a k'Beitzah. The Gemara responds that these husks are not Shomrim, but rather Yados. Rashi explains that the Gemara could have answered this proof the same way it did previously, saying that although the husks are Shomrim, Tana d'Vei Rebbi Yishmael refers to Shomrim of a Biryah, and it is only a Biryah that can have two Shomrim which combine.
The RASHASH and TIFERES YAKOV have difficulty with Rashi's explanation. Earlier, when the Gemara discusses how large a food must be in order for its Shomer to be considered a Shomer with regard to the laws of Tum'as Ochlin, the Gemara says that the food can be even smaller than a bean as long as it is a Biryah. In the Gemara here, where the issue is whether or not two separate Shomrim can be combined, what difference does it make whether the food that they protect is a Biryah or not? The question of two Shomrim seems to be whether a food can have two "guards." If it is possible to have two "guards," then even if the food is not a significant size, it should be able to have two Shomrim! If, on the other hand, it is not possible for an item to have two Shomrim, then even a Biryah should also not have two Shomrim. Why should the logic of Biryah make a difference in this case?
Due to this question, the TOSFOS HA'ROSH rejects the explanation of Rashi, and he says that this is the reason why the Gemara later (119b) does not give the answer of "Biryah." This also seems to be the reason behind the statement of the CHIDUSHEI HA'RAN who states that it is understandable why the Gemara (119b) does not give the answer of "Biryah."
(b) The CHIDUSHIM U'VI'URIM suggests that Rashi understands the logic of Biryah in the Gemara in an entirely different way. When the Gemara answers that the Shomer of a Biryah is considered a Shomer even though the food is less than the size of a bean, this is not because a Biryah is important. The Gemara is saying that because the grain was created with a husk guarding it, the husk was "born to be a Shomer" for this grain. A food that has a protective covering that was not created with it must be the size of a bean in order for the covering to be considered a Shomer.
This approach explains the words of Rashi later (119b) when he says that when something is "created" with two husks, they automatically are called "Shomrim," since they were created as such.
However, the Chidushim u'Vi'urim himself rejects this possibility. The Mishnah in Ukztin (2:4; see BARTENURA there) teaches that an onion cannot have two Shomrim, even though its peels were created this way.
He concludes, therefore, that these words must have been inserted into Rashi's commentary and are not part of Rashi's original words. This is consistent with the SHITAH MEKUBETZES who writes that he did not find this statement in Rashi's manuscript. (Y. MONTROSE)