אָמַר רַב יְהוּדָה מִדִּיסְקַרְתָּא תָּא שְׁמַע בָּהֶם יָכוֹל בְּכוּלָּן תַּלְמוּד לוֹמַר מֵהֶם אִי מֵהֶם יָכוֹל מִקְצָתָן תַּלְמוּד לוֹמַר בָּהֶם Rav Yehuda from Diskarta said: Come and hear the following halakhic midrash concerning the ritual impurity of creeping animals. The verse states: “Whoever touches them when they are dead shall be impure” (Leviticus 11:31). One might have thought this halakha applies only to all of them, i.e., to complete creatures. Therefore, the verse states: “And upon whatever any of them, when they are dead, fall, it shall be impure” (Leviticus 11:32), which indicates that part of these creatures also imparts impurity. If the halakha were derived solely from the phrase “of them,” one might have thought that it applies even to a small part of them. The verse therefore states: “Them,” which means all of them.
הָא כֵּיצַד עַד שֶׁיִּגַּע בְּמִקְצָתָן שֶׁהוּא כְּכוּלָּן וְשִׁיעֲרוּ חֲכָמִים בְּכַעֲדָשָׁה שֶׁכֵּן הַחוֹמֶט תְּחִלַּת בְּרִיָּיתוֹ בְּכַעֲדָשָׁה שְׁמַע מִינַּהּ שִׁיעוּרָא גְּמִירִי לַהּ How so? How can one reconcile the two verses? He does not become ritually impure unless he touches at least part of them that is equal in measure to all of them, i.e., a large part. And the Sages calculated that this is the volume of a lentil-bulk. Why is this? As the start of the formation of a skink, one of the eight impure creeping animals, is the size of a lentil-bulk. This concludes the halakhic midrash. With regard to the issue at hand, one can learn from here that it is learned as a tradition that the amount for a creature to be considered whole is a lentil-bulk. If so, an ant missing a limb should likewise not have the status of a creature.
אָמַר רַב שְׁמַעְיָה כִּי בָּעִינַן שִׁיעוּרָא דְּבִדְלָא הָוְיָא כַּעֲדָשָׁה לָא מְטַמָּא דְּלָא נָפְלָה בַּהּ נְשָׁמָה אֲבָל נָפְלָה בַּהּ נְשָׁמָה לָא תִּיבְּעֵי לָךְ: Rav Shemaya said, in refutation of this argument: When we require the above amount, that if it is not the volume of a lentil-bulk it does not impart impurity, the requirement applies only in a case where the creature does not have a living soul before it grows to the size of a lentil. However, if it does have a soul, this volume is not required. If the creature can survive, perhaps it does impart impurity even if it is lacking a limb. Consequently, with regard to an ant that is missing a limb, the dilemma remains unresolved for you.
הַשִּׁדְרָה וְהַגּוּלְגּוֹלֶת אִיבַּעְיָא לְהוּ שִׁדְרָה וְגוּלְגּוֹלֶת תְּנַן אוֹ דִּלְמָא אוֹ שִׁדְרָה אוֹ גוּלְגּוֹלֶת אָמַר רָבָא תָּא שְׁמַע שִׁדְרָה שֶׁגֵּירַד רוֹב עִילְעִין שֶׁבָּהּ טְהוֹרָה וּבְקֶבֶר אֲפִילּוּ מְשׁוּבֶּרֶת אוֹ מְפוֹרֶקֶת טְמֵאָה מִפְּנֵי הַקֶּבֶר § The mishna taught that a nazirite must shave for impurity imparted by a spine and skull. A dilemma was raised before the Sages: Did we learn a spine and [ve] skull together? Or perhaps the mishna means either a spine or a skull. Does the conjunctive vav signify: And, or: Or? Rava said: Come and hear a resolution from a baraita: In the case of a spine, the majority of whose ribs were removed while the spine itself remained intact, it is ritually pure. And if it was in a grave, even if it was broken or disassembled, it is impure, due to the grave, which joins all the bones together.
טַעְמָא מִשּׁוּם דְּגֵירַד הָא לָא גֵּירַד טָמֵא שְׁמַע מִינַּהּ אוֹ שִׁדְרָה אוֹ גוּלְגּוֹלֶת קָתָנֵי הָא לָא קָתָנֵי הָא קָא מַשְׁמַע לַן דְּכִי גֵּירַד טְהוֹרָה אִידַּךְ תִּיבְּעֵי לָךְ The Gemara infers from this baraita: The reason it is ritually pure in the first case is due to the fact that the ribs were removed, from which it may be inferred that if they were not removed, it is impure on its own, even without the skull. Learn from this that the mishna teaches: Either a spine or a skull. The Gemara rejects this claim: The baraita does not teach this explicitly. It does not state that if the ribs were not removed the spine imparts ritual impurity by itself. Rather, the baraita teaches us this, that if the ribs were removed the spine is pure. And as to the other issue, the impurity of a spine on its own, the dilemma remains unresolved for you.
תָּא שְׁמַע רַבִּי יְהוּדָה אוֹמֵר שִׁשָּׁה דְּבָרִים רַבִּי עֲקִיבָא מְטַמֵּא וַחֲכָמִים מְטַהֲרִין וְחָזַר בּוֹ רַבִּי עֲקִיבָא וּמַעֲשֶׂה שֶׁהֵבִיאוּ קוּפָּה מְלֵאָה עֲצָמוֹת לְבֵית הַכְּנֶסֶת שֶׁל טַרְסִיִּים וְהִנִּיחוּהָ בַּאֲוִיר וְנִכְנַס תּוֹדוֹס הָרוֹפֵא וְכׇל הָרוֹפְאִים [עִמּוֹ] וְאָמְרוּ אֵין כָּאן שִׁדְרָה מִמֵּת אֶחָד The Gemara further suggests: Come and hear a resolution from the Tosefta (Oholot 4:2). Rabbi Yehuda says that Rabbi Akiva deems six items impure that the Rabbis deem pure, and Rabbi Akiva later retracted his opinion. And an incident occurred in which they brought a box that was full of bones to the synagogue of blacksmiths [tarsiyyim], and they placed it in an open airspace, not under the roof, so that it would not impart ritual impurity. And Todos the doctor entered and all the other doctors entered with him, and they said, after examining the pile: There is not a full spine from one corpse here.
טַעְמָא דְּלֵיכָּא שִׁדְרָה דְּמֵחֲדָא הָאִיכָּא אוֹ שִׁדְרָה אוֹ גוּלְגּוֹלֶת דְּמֵחֲדָא נָזִיר מְגַלֵּחַ עָלֶיהָ שְׁמַע מִינַּהּ אוֹ שִׁדְרָה אוֹ גוּלְגּוֹלֶת תְּנַן לָא מִיבַּעְיָא קָאָמַר לָא מִיבַּעְיָא שִׁדְרָה וְגוּלְגּוֹלֶת דְּמִמֵּת אֶחָד לֵיכָּא אֶלָּא אֲפִילּוּ אוֹ שִׁדְרָה מִמֵּת אֶחָד אוֹ גוּלְגּוֹלֶת מִמֵּת אֶחָד לֵיכָּא The Gemara infers from this incident: The reason it is ritually pure is due to the fact that there was no spine from one corpse, from which one can infer that if there is either a spine or a skull from one corpse, a nazirite must shave due to it. Learn from this that we learned in the mishna that a nazirite shaves either for a spine or a skull. The Gemara rejects this argument: The tanna of the baraita is speaking utilizing the style of: It is not necessary, as follows: It is not necessary to state that there is no spine and skull from one corpse in the box, but even the remains of either a spine from one corpse or a skull from one corpse, which together impart impurity, are not present. Instead, there are parts of spines and skulls from several bodies.
תָּא שְׁמַע מִמִּנְיָינָא וּמָה הֵן שִׁשָּׁה דְּבָרִים שֶׁרַבִּי עֲקִיבָא מְטַמֵּא וַחֲכָמִים מְטַהֲרִין עַל אֵבֶר מִן הַמֵּת שֶׁבָּא מִשְּׁנֵי מֵתִים וְעַל אֵבֶר מִן הַחַי שֶׁבָּא מִשְּׁנֵי בְּנֵי אָדָם וְעַל חֲצִי קַב עֲצָמוֹת שֶׁבָּא מִשְּׁנֵי מֵתִים וְעַל רְבִיעִית דָּם הַבָּא מִשְּׁנַיִם וְעַל עֶצֶם כִּשְׂעוֹרָה שֶׁנֶּחְלַק לִשְׁנַיִם וְהַשִּׁדְרָה וְהַגּוּלְגּוֹלֶת The Gemara further suggests: Come and hear from the tally in the above baraita: And what are those six items that Rabbi Akiva deems ritually impure and the Rabbis deem ritually pure? They consist of a limb from a corpse that comes from, i.e., is combined with, two corpses; and a severed limb from a living person that comes from two living people; and half-kav of bones that come from two corpses; and a quarter-log of blood that comes from two corpses; and of a bone that is a barley-grain-bulk, even from one body, that was divided into two; and the spine and the skull from two corpses.