The Mishnah does not follow R. Dosa; as the Baraisa taught - R. Dosa says that one may redeem Ma'aser Sheni onto a token. The Chachamim prohibit it.

What's R. Dosa's reason? The pasuk states (Devarim 14:25), "and bind up {Vesarta} the money'' - something that can be wrapped up {Nitzrar} (which includes a token).

What's the Rabbanan's reason? The pasuk includes something that is minted {Tzurah} and is in circulation as a result.

(R. Yosi citing R. Yochanan): According to R. Dosa, one may redeem Ma'aser Sheni onto a Litra of silver (even though it is not a coin, since it's weight is known and it's somewhat spendable).

If R. Yochanan would have merely said 'a Litra' (a piece), one could have said that it applies to gold as much as silver. And if he would have merely said 'silver', one could have said that one could redeem even onto broken bowls and pans of silver - therefore he said 'a Litra of silver'.

The Baraisa taught that R. Dosa disagrees with the Tana of our Mishnah permits redeeming onto a token. All agree that one may not redeem onto money given to a bathhouse attendant (who would accept coins as if they were worth even more than their actual worth).

That's according to their value for the bathhouse attendant, but one may redeem according to their value for the Turmus bean seller.

(R. Yosi citing R. Yonasan): If there's a coin that has become disqualified but the government still accepts it, it's like a token (and it's a dispute between Rabbanan and R. Dosa).

(R. Chiya citing R. Yonasan): (Disagreeing) It's like a coin of earlier kings (about which a Tosefta - in Ma'aser Sheni 1:5 - teaches that they may be used to redeem).

Let us say that if it can be spent because of its image, it may be used to redeem and if not, it may not.

A coin that was issued by a person who revolted, such as Ben Kuziva, may not be used to redeem.

Question: What's the law concerning coins that were exchanged with Nesech wine (used for idolatry)?

Answer: Such a case came before R. Imi and he said, "Take their benefit to the dead sea.'' (i.e. one may not gain any benefit from such coins.)

Question: What's the law concerning coins of Diskanis (an earlier king)?

Answer (R. Yaakov bar Zavdi citing R. Abahu): One may redeem with them according to their value for the Turmus bean seller.

When he wants to spend them (in Yerushalayim), he should redeem them according to the rate he had redeemed the Ma'aser Sheni onto them.