Negaim 5:3-6:1
Negaim5: 3
שְׂעַר פְּקוּדָה — עֲקַבְיָא בֶּן מַהֲלַלְאֵל וַחֲכָמִים מְטַהֲרִין. אֵיזֶה הוּא שְׂעַר פְּקוּדָה? מִי שֶׁהָיְתָה בוֹ בַהֶרֶת וּבָהּ שֵׂעָר לָבָן, הָלְכָה הַבַּהֶרֶת וְהִנִּיחָהּ לְשֵׂעָר לָבָן בִּמְקוֹמוֹ, וְחָזְרָה. עֲקַבְיָא בֶּן מַהֲלַלְאֵל מְטַמֵּא, וַחֲכָמִים מְטַהֲרִין. אָמַר רַבִּי עֲקִיבָא: מוֹדֶה אֲנִי בָזֶה שֶׁהוּא טָהוֹר. אֵיזֶה הוּא שְׂעַר פְּקוּדָה? מִי שֶׁהָיְתָה בוֹ בַהֶרֶת כִּגְרִיס וּבָהּ שְׁתֵּי שְׂעָרוֹת, וְהָלַךְ הֵימֶנָּה כַּחֲצִי גְרִיס, וְהִנִּיחוֹ לְשֵׂעָר לָבָן בִּמְקוֹם הַבַּהֶרֶת, וְחָזַר. אָמְרוּ לוֹ: כְּשֵׁם שֶׁבִּטְּלוּ אֶת דִּבְרֵי עֲקַבְיָא, אַף דְּבָרֶיךָ אֵינָן מְקֻיָּמִין.
‘‘Deposited hair’’ — Akavya ben Mahalalel rules it tamei and the Sages rule it tahor. What is ‘‘deposited hair’’? Someone had a baheres with white hair. The baheres disappeared, leaving the white hair in place, and [subsequently] returned. Akavya ben Mahalalel rules ‘‘deposited hair’’ to be tamei, and the Sages rule it tahor. R’ Akiva said: ‘‘I agree that this case is tahor [because it is not ‘deposited hair’]. What is ‘deposited hair’? Someone had a baheres the size of a gris that contained two [white] hairs. [The baheres] receded half a gris, leaving the white hair on the remaining baheres, and [subsequently] returned.’’  They said to him: ‘‘Just like Akavya’s opinion is disregarded, so is your opinion not upheld.“
Negaim5: 4
כָּל סָפֵק נְגָעִים בַּתְּחִלָּה, טָהוֹר עַד שֶׁלֹּא נִזְקַק לְטוּמְאָה. מִשֶּׁנִּזְקַק לְטוּמְאָה, סְפֵקוֹ טָמֵא. כֵּיצַד? שְׁנַיִם בָּאוּ אֵצֶל כֹּהֵן, בָּזֶה בַּהֶרֶת כִּגְרִיס, וּבָזֶה כְּסֶלַע. בְּסוֹף שָׁבוּעַ, בָּזֶה כְּסֶלַע וּבָזֶה כְּסֶלַע, וְאֵין יָדוּעַ בְּאֵיזֶה מֵהֶן פָּשָׂה, בֵּין בְּאִישׁ אֶחָד בֵּין בִּשְׁנֵי אֲנָשִׁים, טָהוֹר. רַבִּי עֲקִיבָא אוֹמֵר: בְּאִישׁ אֶחָד טָמֵא וּבִשְׁנֵי אֲנָשִׁים טָהוֹר.
Any doubt concerning negaim initially is [ruled] tahor, as long as [the afflicted person] has not been confirmed tamei. Once [the afflicted person] has been confirmed tamei, a doubt is [ruled] tamei. How so? Two [people] came to a Kohen, one with a baheres the size of a gris, and the other with [a baheres] the size of a sela. At the end of the week, both [beharos] are the size of a sela, and it is unknown which is the one that spread. Whether [both beharos are] on one person or on two people, [each baheres] is [ruled] tahor. R’ Akiva says: With one person it is tamei; with two people it is tahor.
Negaim5: 5
מִשֶּׁנִּזְקַק לְטוּמְאָה, סְפֵקוֹ טָמֵא. כֵּיצַד? שְׁנַיִם שֶׁבָּאוּ אֵצֶל כֹּהֵן, בָּזֶה בַּהֶרֶת כִּגְרִיס, וּבָזֶה כְּסֶלַע. בְּסוֹף שָׁבוּעַ, בָּזֶה כְּסֶלַע וְעוֹד, וּבָזֶה כְּסֶלַע וָעוֹד, שְׁנֵיהֶן טְמֵאִין. אַף עַל פִּי שֶׁחָזְרוּ לִהְיוֹת כְּסֶלַע וּכְסֶלַע, שְׁנֵיהֶן טְמֵאִין, עַד שֶׁיַּחְזְרוּ לִהְיוֹת כִּגְרִיס. זֶה הוּא שֶׁאָמְרוּ: מִשֶּׁנִּזְקַק לְטוּמְאָה, סְפֵקוֹ טָמֵא.
Once [the afflicted person] has been confirmed tamei, a doubt is [ruled] tamei. How so? Two people came to a Kohen, one with a baheres the size of a gris and the other with [a baheres] the size of a sela. If at the end of the week, both [beharos] are larger than a sela, they both become confirmed tamei. Even if both [negaim] revert to the size of a sela, they both remain tamei, until they both become [as small as] a gris. This is what was said: Once [the afflicted person] has been confirmed tamei, a doubt is [ruled] tamei.
Negaim6: 1
גּוּפָהּ שֶׁל בַּהֶרֶת כִּגְרִיס הַקִּלְקִי מְרֻבָּע. מְקוֹם הַגְּרִיס תֵּשַׁע עֲדָשׁוֹת. מְקוֹם עֲדָשָׁה אַרְבַּע שְׂעָרוֹת. נִמְצְאוּ שְׁלֹשִׁים וְשֵׁשׁ שְׂעָרוֹת.
A basic baheres is the size of a Cilician gris squared. The area of a gris is equivalent to nine lentils. The area of a lentil is equivalent to [the area on which] four hairs [grow]. Thus, there are thirty-six hairs [in a nega].