Appearances of negaim are two that are four. Ba|hsp|heres is bright like snow. Secondary to it is like the lime of the Sanctuary. S’eis is like the membrane of an egg. Secondary to it is like white wool, these are the words of R’ Meir. And the Sages say: S’eis is like white wool; secondary to it is like the membrane of an egg.

The reddish version of the snow-white [nega appears] like wine mixed with snow. The reddish version of the lime-[colored nega] is like blood mixed with milk. These are the words of R’ Yishmael. R’ Akiva says: The red version of both of them is [the color of] wine mixed with water, except that [the red tinge] of snow is bright whereas that of lime is duller.

These four appearances combine with one an- other to make tahor, to confirm, or to confine: to confine that which remains the same at the end of the first week; to make tahor that which remains the same at the end of the second week; to confirm that which develops living skin or white hair, either initially, at the end of the first week, at the end of the second week, [or] after being declared tahor; to confirm that which develops an expansion [either] at the end of the first week, at the end of the second week, [or] after being declared tahor; to confirm someone who turns completely white after being declared tahor; to make tahor someone who turns completely white after being confirmed or confined. These are the appearances of negaim upon which depend all negaim.

R’ Chaninah, the administrator of the Kohanim, says: There are sixteen appearances of negaim. R’ Dosa ben Harkinos says: There are thirty-six appearances of negaim. Akavya ben Mahalalel says: Seventy-two. R’ Chaninah, the administrator to the Kohanim, says: Negaim are not examined initially on Sunday, because its seventh day falls on Sabbath; nor on Monday, because its second week falls on Sabbath; nor on Tuesday for houses, because the third week falls on Sabbath. R’ Akiva says: [A nega] is examined on any day. If [an examination] falls on Sabbath, it is postponed until after Sabbath, and this causes both leniency and stringency.