[8a - 24 lines; 8b - 25 lines]
We recommend using the textual changes suggested by the Bach and the marginal notes of the Vilna Shas. This section is devoted to any other important corrections that Acharonim have pointed out in the Gemara, Rashi and Tosfos.
 Rashi 8a DH Pischah Shiv'ah Asar ד"ה פתחה שבעה עשר:
The words "Yatzesah Yemei ha'Zov" יצתה ימי הזוב
should be "Yatzesah mi'Yemei ha'Zov" יצתה מימי הזוב both times that it appears
Should be corrected as suggested by Shitah Mekubetzes #14
 Rashi 8b DH Sheneim Asar ד"ה שנים עשר:
The words "d'Chalu ha'Sheneim Asar Yamim mi'Minyan ha'Acharon"דכלו השנים עשרה ימים ממנין האחרון
should be "d'Chol ha'Sheneim Asar Yamim mi'Minyan ha'Acharon"דכל השנים עשרה ימים ממנין האחרון
and should follow the words "O Shema Techilas Nidah Hi" או שמא תחילת נדה היא (Rav Rensburg; of the many Girsa suggestions for correcting this Rashi, this appears to be the simplest.)
The words "ul'Sof Shishah Kalu Yemei Nidah" ולסוף ששה כלו עמי נדה
should be "ul'Sof Shiv'ah Kalu Yemei Nidah" ולסוף שבעה כלו ימי נדה (Ya'avetz, Rav Rensburg)
Should be corrected as suggested by Shitah Mekubetzes #11
 Rashi DH Chutz ד"ה חוץ:
Should be corrected as suggested by Shitah Mekubetzes #15
 Rashi DH Lo Nir'eh la'Chachamim ד"ה לא נראה לחכמים:
The words "v'Lo Mefaresh" ולא מפרש
should be "Lo Mefaresh" לא מפרש
1)[line 12]פתח בטועהPESACH B'TO'AH (YEMEI NIDAH VI'YEMEI ZIVAH)
By Torah Law, a woman who has her period is a Nidah for seven days. It makes no difference whether she saw blood only one time or for the entire seven days. At the end of seven days, after nightfall, she immerses in a Mikvah to become Tehorah.
(The current practice is to consider all women who have a show of blood to be a Zavah and therefore they must have seven clean days before they go to the Mikvah.)
(b)DAM ZIVAH (ZAVAH)
1.The eleven days that follow the seven days of Nidah (see (a) above) are "days of Zivah." If a woman experiences bleeding during these days for one or two consecutive days, whether the bleeding is b'Ones (due to an external cause, see Background to Bava Kama 24:5:b) or not, she becomes a Zavah Ketanah and is Teme'ah.
2.If she does not experience bleeding the following night and day, she may immerse in a Mikvah during the day to become Tehorah. She may even immerse on the morning immediately following the day on which she saw blood, but her Tum'ah and Taharah are contingent upon whether or not she sees blood afterwards on that day. She is called a Shomeres Yom k'Neged Yom, because she must watch the following day to confirm whether or not she sees blood.
3.If a woman has a show of blood for three consecutive days during her 11 days of Zivah, she becomes a Zavah Gedolah. In order for her to become Tehorah, she must count seven "clean days" during which she verifies that she has no other show of blood. On the morning of the seventh clean day she immerses in a Mikvah. If she does not experience bleeding during the rest of the day she is Tehorah and no longer a Zavah. A Zavah Gedolah must bring a Korban Zavah to permit her to enter the Beis ha'Mikdash or to eat Kodshim. The Korban is two Torim or two Benei Yonah, one offered as an Olah and one as a Chatas (Vayikra 15:25-30).
1.The first time a woman becomes Tamei by seeing blood (after the cycle of 18 days is completed) she starts anew the cycle and becomes a Nidah for seven days. If a woman sees blood during the 11 days of Zivah, she is a Zavah Ketanah or Zavah Gedolah.
2.If a woman has erred ("To'ah") in her count and does not know whether she saw the blood during the days of Nidah or of Zivah, she must follow the more stringent of the two courses of action. If she sees blood only after a period of 7 to 17 days (as the Gemara explains in detail here), she knows for sure that she is at the beginning ("Pesach") of her cycle and the next time she sees blood, she is a Nidah and not a Zavah.
2a)[line 13]בנגעיםB'NEGA'IM (HESGER / HECHLET)
When a person, article of clothing made of wool or linen, or a house develops a mark of Tzara'as, a Kohen must ascertain whether or not it is Tamei. Under certain conditions, the Kohen puts them in quarantine (Hesger), and returns after a week to see what changes, if any, have happened to the mark. A person, article of clothing, or house that is confirmed to be Tamei is called Muchlat.
b)[line 14]פחות משבוע, נגעי אדםPACHOS MI'SHAVU'A, NIG'EI ADAM- the period of quarantine (Hesger) for Nega'im of a person is [not less than] a week (see Background to Erchin 3:4b for the different types of Nega'im of a person and their respective laws). The period of quarantine for Shechin and Michvah is only one week, after which the Kohen declares him either Tahor or Muchlat.
3)[line 15]נגעי בתיםNIG'EI BATIM
(a)The marks of Tzara'as for houses consist of intense green or intense red streaks or spots that are at least the size of two Gerisin (a Gris is a Cilician bean, approximately the size of a dime) (Nega'im 12:3). If Tzara'as is found on the walls of a house, it is put into quarantine by a Kohen for a week. Before the Kohen puts the house into quarantine, he commands that the house be emptied of its contents to prevent its utensils from becoming Tamei.
(b)The Torah states (Vayikra 14:39) "v'Shav ha'Kohen," to prescribe that the Kohen return six days later to check the house. If the Tzara'as has spread, one must remove (Choletz) the stones with Tzara'as from the house, scrape off the surrounding plaster, insert new stones and re-plaster the entire house. The house is then put into quarantine for another week. If the Tzara'as returns to the house during the following week, the owner must dismantle (Notetz) the entire house (Vayikra 14:45). The stones from the house must be taken out of the city, and they remain Asur b'Hana'ah forever.
(c)On the other hand, if the Tzara'as did not change after the first week, the Kohen leaves it as is and returns again six days later. The verse states (Vayikra 14:44) "u'Va Ha'kohen," which means "if, when the Kohen comes back to the house to inspect it a second time, he finds that the spot of Tzara'as has spread, the house is Tamei." Chazal teach that this verse is referring to a spot of Tzara'as that does not spread during its first week. The Kohen "comes back to the house" after a second week to see whether the spot has spread, remains, or has disappeared. If the Tzara'as has either spread or remained, one must remove (Choletz) the stones with Tzara'as from the house, scrape off the surrounding plaster, insert new stones and re-plaster the entire house. The house is then put into quarantine for another week (Vayikra 14:40). If the Tzara'as returns to the house during the following week, the owner must dismantle (Notetz) the entire house (Vayikra 14:45). The stones from the house must be taken out of the city, and they remain Asur b'Hana'ah forever.
(d)Even though the words "v'Shav" and "u'Va" are not identical, they are referring to the same action; namely, the Kohen entering the house to inspect it. This relates the two verses to each other with a Gezerah Shavah. Just as the house is not dismantled if the Tzara'as spreads during the first week — unless the stones are scraped and the Tzara'as returned to the house after a week of quarantine — so, too, the house is not dismantled if the Tzara'as spread during the second week unless it returns to the house after the quarantine period that follows the scraping.
(e)If during one of the inspections at the end of the first or second week the Kohen finds that the Tzara'as has disappeared or diminished in intensity such that it can no longer be classified as a Nega, the location of the spot alone is scraped and the house is declared Tahor after the owner follows the procedure for being Metaher houses (see Background to Sukah 13:11). (RAMBAM Hilchos Tum'as Tzara'as 15:2)
4)[line 21]חדשים המעובריםCHODASHIM HE'ME'UBARIM - leap (lit. full) months
(a)Leap months are months that have 30 days. Since the lunar month is approximately 29 1/2 days long, the months must be either 29 or 30 days long.
(b)Nowadays, the calendar is fixed, with the following number of days in each month:
Cheshvan: 29 or 30
Kislev: 29 or 30
(Adar I: 30)
Adar (II): 29
(c)A year in which both Cheshvan and Kislev have 30 days is called a "Shanah Mele'ah."
(d)A year in which both Cheshvan and Kislev have 29 days is called a "Shanah Chaserah."
(e)A year in which Cheshvan has 29 days and Kislev has 30 days is called "k'Sidran."