R' Yehoshua said: I have heard that the saris performs chalitzah and that chali- tzah is performed with his wife; and [I have also heard] that the saris does not perform chalitzah and that chalitzah is not performed with his wife —- and I cannot explain [it]. R' Akiva said: I will explain [it]. The [person rendered a] saris by [an act of] man performs chalitzah and chalitzah is performed with his wife, because he had a period of suitability; the congenital saris does not perform chalitzah and chalitzah is not performed with his wife, because he had no period of suitability. R' Eliezer says: Not so; rather the congenital saris performs chalitzah and chalitzah is performed with his wife, since he may be cured; the [person rendered a] saris by [an act of] man does not perform chalitzah and chalitzah is not performed with his wife, since he cannot be cured. R' Yehoshua ben Beseira testified about ben Megusas, [who lived] in Jerusalem, [who was] a [person rendered a] saris by [an act of] man, and yibum was performed with his wife, supporting R' Akiva's statement.