A baheres the size of a gris that contained a michyah the size of a lentil — [if] the baheres spread, it is tamei; [if] it receded, it [becomes] tahor. [If] the michyah expanded, [the baheres] is tamei; [if the michyah] receded, [the baheres] is tahor.

A baheres the size of a gris that contained a michyah less than a lentil — [if] the baheres expanded, it becomes tamei; [if] it receded, it becomes tahor. [If] the michyah expanded, [the baheres] becomes tamei. [If the michyah] receded, R’ Meir renders it tamei and the Sages render it tahor, because a nega does not expand inwards.

A baheres larger than a gris contained more than a lentil of living skin — [if] they grew or receded, [the baheres] is tamei, as long as they do not recede below the minimum size.

A baheres the size of a gris is surrounded by living skin [the width] of a lentil, and [another] baheres is outside the living skin — the inner one is confined and the outer one is confirmed. Said R’ Yose: The michyah is not a symptom of tumah for the outer [nega] since a baheres is inside it. [If the michyah] receded, or disappeared, Rabban Gamliel says: If it diminished on the inner side, it is a sign of expansion for the inner [nega], and the outer [nega] becomes tahor. But if [it diminished] from the outer side, the outer [nega] becomes tahor and the inner [nega] shall be confined. R’ Akiva says: Either case is tahor.